Performing power compensation in a region of an ac power grid

Abstract

A power compensation system comprises a compensation control device (22), one or more enhanced power distribution networks (10) connected to a power grid and one or more compensation handling devices (26), each associated with a corresponding enhanced power distribution network (10), where each such network (10) is provided in a region of the grid and comprises an inverter (28) capable of operating in an active compensating role, a coil mimicking role and a capacitor mimicking role. The compensation control device (22) investigates the stability of the grid in the region and sends an instruction to at least some compensation handling devices (26) to make the corresponding inverter (28) act according to a role for stabilising the power grid in the region and each compensation handling device (26) obtains a time of a central clock, obtains a time of a crossing of a reference level of a phase at the enhanced power distribution network, determines a first time offset from the central clock as a difference in time between the time of the reference level crossing and the time of the central clock, receives the instruction to act in a role and orders the corresponding inverter (28) to act in the instructed role with a timing that is based on the central clock adjusted with the first time offset.

Description

[0001] PERFORMING POWER COMPENSATION IN A REGION OF AN AC POWER GRID

[0002] TECHNICAL FIELD

[0003] The invention generally relates to stabilizing a region of a power grid. More particularly, the invention relates to a power compensating arrangement and a method, computer program and computer program product for handling power compensation performed by a first enhanced power distribution network adapted to be connected to a power grid, a compensation control device and a method, computer program and computer program product for controlling a power compensation in a region of a power grid as well as to a power compensation system comprising a compensation control device for performing power compensation in a power grid, one or more enhanced power distribution networks connected to the power grid and one or more compensation handling devices.

[0004] BACKGROUND

[0005] Alternating Current (AC) power grids are important in a national infrastructure that provides electricity to consumers, where such consumers typically act as loads of the power grid. In each moment, energy needs to be put into the AC power grid that closely balance out all the loads taking energy out from it.

[0006] If not in balance, the frequency (often 50Hz or 60Hz) will start to increase or decrease.

[0007] Some stability is given to the AC power grid by large rotating machines, such as generators with turbine on same shaft, that can be found at nuclear plants and other large power plants. This is flywheel stored energy. Such a flywheel takes energy from the AC power grid while frequency is increasing (flywheel mass accelerating, rotating faster). Likewise, give energy back to the AC power grid while frequency is decreasing (flywheel mass decelerating, rotating slower).

[0008] Those large rotating generators provide good stability by counteracting quick changes in frequency during change of energy outtake from the AC power grid.

[0009] Another way to put it is that during short moments of excess energy, that excess energy is stored in the rotation of a flywheel. During short moments, energy shortage is bridged by taking energy from a flywheel. In some countries, such as Sweden, some of those large rotating generators with turbine on same shaft has been taken off-line as a few nuclear plants have been turned off, leaving the AC power grid with less stabilizing flywheel mass than before.

[0010] Also, the source of energy has shifted to smaller power plants, like wind and solar power plants. Note that wind power plants do have rotating generators. However, these are of another type (asynchronous machine) than the type used at large power plants (synchronous machine). The asynchronous machine does not provide the same flywheel stability to the AC power grid as the synchronous machine.

[0011] So, the shift to wind and solar based energy further reduces the amount of stabilizing flywheel mass compared with the amount of energy produced.

[0012] Furthermore, traditional large energy sources, such as Hydro Power sources, may be located far away from the majority of the new energy sources and therefore when wind and solar energy input is low, a first region of the power grid that mainly uses these small renewable energy sources may rely on energy from a second region with the above-mentioned large traditional energy sources.

[0013] There may also exist export of electric energy from the first region. This increases the electric load as seen in the first region leading to more electric energy over time needing to pass power transmission lines from the second region to the first region.

[0014] Let's summarize this so far.

[0015] • The first region of the national power grid has less stabilizing flywheel mass than before.

[0016] • More energy over time is fed into and through the first region.

[0017] Those things both lead to a less stable AC power grid in the first region.

[0018] This means that added stability need to come from elsewhere. That elsewhere is from the large hydro power stations in the second region. However, there are some long-distance power lines inbetween. In order to be able to provide stabilization, it is not possible to run the long-distance power line at full throttle. There is a need to leave some headroom.

[0019] If the AC power grid could be locally stabilized in the first region, then the above-mentioned longdistance power distribution lines could be run at full throttle. Thus, also allowing more electric energy to be exported. Thereby a larger portion of solar and wind-based energy could also be handled in the AC power grid.

[0020] There is thus a need for providing local stabilizing of an AC power grid.

[0021] SUMMARY

[0022] One object of the invention is thus to provide local stabilizing of an AC power grid.

[0023] This object is according to a first aspect achieved by a power compensating arrangement comprising a compensation handling device, where the compensation handling device handles power compensation performed by a first enhanced power distribution network that is provided for being connected to a three-phase power grid. The first enhanced power distribution network comprises at least one inverter that is capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role. The compensation handling device also comprises a processor operative to: obtain a time of a central clock, obtain, at the first enhanced power distribution network, a time of a crossing of a reference level of a phase, determine a first time offset from the central clock as a difference in time between the time of the crossing of the reference level and the time of the central clock, receive, from a compensation control device, an instruction to act in at least one of the roles, and order the inverter to act in the at least one instructed role, where the acting in the at least one instructed role is performed using a timing that is based on the central clock adjusted with the first time offset.

[0024] The object is according to a second aspect achieved by a method of handling power compensation performed by a first enhanced power distribution network that is adapted to be connected to a three-phase power grid. The first enhanced power distribution network comprises at least one inverter that is capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role. The method is performed in a compensation handling device and comprises: obtaining a time of a central clock, obtaining a time of a crossing of a reference level of a phase at the enhanced power distribution network, determining a first time offset from the central clock as a difference in time between the time of the crossing of the reference level and the time of the central clock, receiving, from the central compensation control device, an instruction to act in at least one of the roles, and ordering the inverter to act in the at least one instructed role, where the acting in at least one role is performed with a timing that is based on the central clock adjusted with the first time offset.

[0025] The object is according to a third aspect achieved by a computer program for handling power compensation performed by a first enhanced power distribution network adapted to be connected to a three-phase power grid, where the first enhanced power distribution network comprises at least one inverter that is capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role. The computer program comprises computer program code which when run by a processor of a compensation handling device implements the method according to the second aspect.

[0026] The at least one object is according to a fourth aspect achieved by a computer-readable medium for handling power compensation performed by a first enhanced power distribution network adapted to be connected to a three-phase power grid, where the first enhanced power distribution network comprises at least one inverter capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role. The computer readable-medium comprises computer program code which when run by a processor of a compensation handling device implements the method according to the second aspect.

[0027] The timing used when acting in at least one role can be considered to be an ordered timing, which ordered timing is thus a timing that is based on the central clock adjusted with the first time offset. The ordered timing may be a timing that is the first time offset added to the time of the central clock.

[0028] The active compensating roles may comprise an active power load role and an active power source role. An active power load role may also be considered the role of mimicking a (positive) resistor and the active power source role may be considered to be the role of mimicking a negative resistor.

[0029] An unadjusted active power load role may be provided through a phase current that is in phase with a corresponding phase voltage, an unadjusted active power source role may be provided through a phase current that is displaced one hundred and eighty degrees from the corresponding phase voltage, an unadjusted coil mimicking role may be provided through a phase current that is ninety degrees after the corresponding phase voltage and an unadjusted capacitor mimicking role may be provided through a phase current that is ninety degrees before the corresponding phase voltage.

[0030] This means that if the role is to be timed with the ordered timing, the active power load role may be operated at a timing of the phase voltage adjusted with the ordered timing, the active power source role may be operated at a timing that is one-hundred and eighty degrees displaced from the phase voltage adjusted with the ordered timing, an unadjusted coil mimicking role may be operated with a timing that is ninety degrees after the timing of the phase voltage adjusted with the ordered timing and a capacitor mimicking role may be operated ninety degrees before the phase voltage adjusted with the ordered timing.

[0031] The crossing of the reference level may be a positive or negative zero-crossing of a phase.

[0032] The phase may be the phase of a waveshape, such as a sinus waveshape. A positive crossing may be a crossing when the waveshape has a positive slope, while a negative crossing may be a crossing when the waveshape has a negative slope. It may additionally be preferred to use the positive crossing.

[0033] According to one variation of the first aspect the compensation handling device is further operative to provide the first time offset to the compensation control device and receive a modified first time offset from the compensation control device.

[0034] According to a corresponding variation of the second aspect, the method further comprises providing the first time offset to the compensation control device and receiving a modified first time offset from the compensation control device.

[0035] In this case, the timing used by the inverter may be based on the central clock adjusted with the modified first time offset. Furthermore, the modified first time offset may be a time where a number of full periods of the phase has been added to or subtracted from the first time offset.

[0036] The number of periods may be the number of periods that the first time offset may slip away from the time of the central clock. The phase may be the phase of a voltage.

[0037] According to another variation of the first aspect, the compensation handling device is in this case further operative to collect voltage measurements and determine the time of the crossing of the reference level of the phase based on the voltage measurements.

[0038] According to a corresponding variation of the second aspect, the method further comprises collecting voltage measurements and determining the time of the crossing of the reference level of the phase based on the voltage measurements.

[0039] The voltage measurements may be collected from a power meter associated with the enhanced power distribution network. Alternatively, they may be collected from the inverter.

[0040] It is additionally possible that the power meter that is associated with the enhanced power distribution network is also a part of the power compensating arrangement.

[0041] It is also possible that the power compensating arrangement comprises the inverter. Furthermore, it is possible that the enhanced power distribution network comprises an energy storage system and / or a power generating system, such as a photovoltaic system. In this case it is additionally possible that the energy storage system and / or power generating system is a part of the power compensating arrangement. It is furthermore possible that the whole enhanced power distribution network is a part of the power compensating arrangement.

[0042] The coil mimicking roles may comprise a first coil mimicking role in which a coil is mimicked in four quadrants, a second coil mimicking role in which a coil is mimicked in two energy supplying quadrants and a third coil mimicking role in which a coil is mimicked in two energy drawing quadrants. The capacitor mimicking roles may comprise a first capacitor mimicking role in which a capacitor is mimicked in four quadrants, a second capacitor mimicking role in which a capacitor is mimicked in two energy supplying quadrants and third capacitor mimicking role in which a capacitor is mimicked in two energy drawing quadrants.

[0043] An energy supplying quadrant may be a quadrant where the product of current and voltage at the enhanced power distribution network is negative, while an energy drawing quadrant may be a quadrant where the product of current and voltage at the enhanced power distribution network is positive. When the product of current and voltage is positive energy goes into the first enhanced power distribution network, while when the product is negative energy goes out of the first enhanced power distribution network.

[0044] The first enhanced power distribution network may be provided in a region of the power grid and it is also possible that the region is connected to a first power source via a connection point, that the first enhanced power distribution network has a timing that is delayed from the first power source with a first delay and that the connection point has a timing that is delayed from the timing of the first power source with a second delay. It is also possible that the region is to change from operating as a load to operating as a source.

[0045] In this case the compensation handling device may be further operative to adjust the timing used in the at least one instructed role based on a first difference if the region is to change from operating as a load to operating as a source, which first difference is the difference between the first delay and the second delay.

[0046] In this case the method of the second aspect may further comprise performing the at least one role with a timing that has been adjusted based on a first difference if the region is to change from operating as a load to operating as a source, which first difference is the difference between the first delay and the second delay.

[0047] The timing adjustment may be an adjustment using twice the first difference or two times the first difference.

[0048] According to yet another variation of the first aspect, the compensation handling device is further operative to receive information about the first difference or the timing adjustment from the compensation control device.

[0049] According to a corresponding variation of the second aspect, the method may further comprise receiving information about the first difference or the timing adjustment from the compensation control device.

[0050] According to another variation of the first aspect, the compensation handling device is further operative to inform the compensation control device of the roles the inverter is capable of occupying. According to a corresponding variation of the second aspect, the method comprises informing the compensation control device of the roles the inverter is capable of occupying.

[0051] The roles that the inverter is capable of occupying may vary over time.

[0052] In this case the informing of the compensation control device about the roles that the inverter is capable of occupying may be performed regularly and the instruction to act in at least one of the roles may be an instruction to act in at least one role that the inverter is presently capable of performing.

[0053] The compensation handling device may be provided as a separate entity that is distinct from a controller of the enhanced power distribution network used for controlling the operation of the inverter. As an alternative it may be combined with this controller.

[0054] The compensation handling device may additionally be a user equipment (UE) that is associated with one or more mobile communication networks.

[0055] The above-mentioned object is according to a fifth aspect also achieved by a compensation control device for performing power compensation in a three-phase power grid, where one or more enhanced power distribution networks are connected to this power grid. Each enhanced power distribution network is also being provided in a region of the power grid and comprises at least one inverter capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role. The compensation control device comprises a processor operative to: investigate the stability of the power grid in the region, and send an instruction to at least some of a number of compensation handling devices, each being associated with a corresponding enhanced power distribution network, to make the inverter of the corresponding enhanced power distribution network act according to at least one of the roles for stabilising the power grid in the region. The inverter, when acting in the at least one role applies a timing that is based on a central clock adjusted with an individual first time offset, which individual first time offset is a difference in time between the time of a crossing of a reference level of a phase at the corresponding enhanced power distribution network and the time of the central clock. The object is according to a sixth aspect also achieved by a method of controlling a power compensation in a region of a three-phase power grid to which one or more enhanced power distribution networks are connected, where each enhanced power distribution network is provided in a region of the power grid and comprises at least one inverter capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role. The method comprises: investigating the stability of the power grid in the region, and sending an instruction to at least some of a number of compensation handling devices, each associated with a corresponding enhanced power distribution network, to make the inverter of the corresponding enhanced power distribution network act according to at least one of the roles for stabilising the power grid in the region. The inverter, when acting in the at least one role applies a timing that is based on a central clock adjusted with an individual first time offset, which individual first time offset is a difference in time between the time of a crossing of a reference level of a phase at the corresponding enhanced power distribution network and the time of the central clock.

[0056] The object is according to a seventh aspect also achieved by a computer program for controlling a power compensation in a region of a three-phase power grid to which one or more enhanced power distribution networks are connected, where each enhanced power distribution network is provided in a region of the power grid and comprises at least one inverter capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role. The computer program comprises computer program code which when run by a processor of a compensation control device implements the method according to the sixth aspect.

[0057] The object is according to an eighth aspect also achieved by a computer-readable medium for controlling a power compensation in a region of a three-phase power grid to which one or more enhanced power distribution networks are connected, where each enhanced power distribution network is provided in a region of the power grid and comprises at least one inverter capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role. The computer readable-medium comprises computer program code which when run by a processor of a compensation control device implements the method according to the sixth aspect.

[0058] According to one variation of the fifth aspect, the compensation control device is further operative to provide the compensation handling devices with the time of the central clock. According to a corresponding variation of the sixth aspect, the method further comprises providing the compensation handling devices with the time of the central clock.

[0059] According to another variation of the fifth aspect, the compensation control device is further operative to obtain individual first time offsets from each of the compensation handling devices, determine an individual modified first time offset for each of the enhanced power distribution networks and provide each individual modified first time offset to the corresponding compensation handling devices.

[0060] According to a corresponding variation of the sixth aspect, the method further comprises obtaining the individual first time offsets from each of the compensation handling devices, determining an individual modified first time offset for each of the enhanced power distribution networks and providing each individual modified first time offset to the corresponding compensation handling devices.

[0061] Also in this case the modified first time offset may be the first time offset to which a number of full periods of the phase has been added.

[0062] According to yet another variation of the fifth aspect, the compensation control device is further operative to investigate if the region acts as a reactive load when investigating the stability of the power grid and being further operative to send instructions that causes a reduction of the reactive load when sending an instruction to make an inverter act according to at least one role.

[0063] According to a corresponding variation of the sixth aspect, the investigating of the stability of the power grid in the region comprises investigating if the region acts as a reactive load and the sending of an instruction to make an inverter act according to at least one role comprises sending an instruction that causes a reduction of the reactive load.

[0064] In this case the instruction may comprise an instruction to mimic a coil in case the load of the region is capacitive and to mimic a capacitor in case the load of the region is inductive.

[0065] As has been previous mentioned, it is possible that the coil mimicking roles comprise a first coil mimicking role, in which a coil is mimicked in four quadrants, a second coil mimicking role in which a coil is mimicked in two energy supplying quadrants and a third coil mimicking role in which a coil is mimicked in two energy drawing quadrants. Similarly, the capacitor mimicking roles may comprise a first capacitor mimicking role, in which a capacitor is mimicked in four quadrants, a second capacitor mimicking role in which a capacitor is mimicked in two energy supplying quadrants and a third capacitor mimicking role in which a capacitor is mimicked in two energy drawing quadrants.

[0066] In this case the sending of an instruction to mimic a coil or a capacitor may comprise sending an instruction to a compensation handling device associated with a first enhanced power distribution network to mimic a coil or a capacitor in two energy supplying quadrants and sending an instruction to a compensation handling device associated with a second enhanced power distribution network to mimic a coil or a capacitor in two energy drawing quadrants.

[0067] According to another variation of the fifth aspect, the compensation control device is further operative to investigate if the region acts as an active load or an active source when investigating the stability and being further operative to send an instruction that causes mitigation of the active load or active source when sending an instruction to make an inverter act according to at least one role.

[0068] According to a corresponding variation of the sixth aspect, the investigating of the stability of the power grid in the region comprises investigating if the region acts as a load or a source and the sending of an instruction to make an inverter act according to at least one role comprises sending an instruction that causes mitigation of the load or source.

[0069] The active compensating roles may comprise an active power load role and an active power source role and the instruction may comprise an instruction to act as an active power source in case the region acts as an active load and to act as an active power load in case the region acts as an active power source.

[0070] Furthermore, the region may be connected to a first power source via a connection point, each enhanced power distribution network may have a timing that is delayed from the first power source with a corresponding first delay and the connection point may have a timing that is delayed from the timing of the first power source with a second delay.

[0071] According to yet another variation of the fifth aspect, the compensation control device is in this case further operative to determine that the region is to change from operating as a load to operating as a source and order the compensation handling devices associated with the enhanced power distribution networks in the region to adjust the timing used in the at least one instructed role based on a first difference, which first difference is the difference between the corresponding first delay and the second delay.

[0072] According to a corresponding variation of the sixth aspect, the method in this case further comprises determining that the region is to change from operating as a load to operating as a source and ordering the compensation handling devices associated with the enhanced power distribution networks of the region to adjust the timing used in the at least one instructed role based on a first difference, which first difference is the difference between the corresponding first delay and the second delay.

[0073] The timing adjustment to use may be twice the first difference or two times the first difference.

[0074] According to another variation of the fifth aspect, the compensation control device is further operative to determine the first difference and inform the compensation handling devices about it or the timing adjustment.

[0075] According to a corresponding variation of the sixth aspect, the method further comprises determining the first difference and informing the compensation handling devices about it or the timing adjustment.

[0076] According to yet another variation of the fifth aspect, the compensation control device is further operative to receive information from the compensation handling devices of the roles the corresponding inverters are capable of occupying and where the instruction to act according to at least one role is an instruction to act in at least one role the inverter is capable of occupying.

[0077] According to a corresponding variation of the sixth aspect, the method further comprises receiving information from the compensation handling devices of the roles the corresponding inverters are capable of occupying and where the instruction to act according to at least one role is an instruction to act in at least one role the inverter is capable of occupying.

[0078] It is additionally possible that the roles that the inverters are capable of occupying vary over time, the information of these capabilities is received regularly and the instruction to act according to at least one role is an instruction to act in at least one role that the corresponding inverter is presently capable of performing.

[0079] A ninth aspect is directed towards a power compensation system comprising a compensation control device for performing power compensation in a three-phase power grid, one or more enhanced power distribution networks connected to the power grid and one or more compensation handling devices, each associated with a corresponding enhanced power distribution network. Each enhanced power distribution network is provided in a region of the power grid and comprises at least one inverter capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role.

[0080] The compensation control device comprises a processor operative to: investigate the stability of the power grid in the region, and send an instruction to at least some of a number of compensation handling devices to make the inverter of the corresponding enhanced power distribution network act according to at least one of the roles for stabilising the power grid in the region, and

[0081] Each compensation handling device in turn comprises a processor operative to: obtain a time of a central clock, obtain a time of a crossing of a reference level of a phase at the enhanced power distribution network, determine a first time offset from the central clock as a difference in time between the time of the crossing of the reference level and the time of the central clock, receive, from the compensation control device, the instruction to act in at least one of the roles, and order the corresponding inverter to act in the at least one instructed role with a timing that is based on the central clock adjusted with the first time offset.

[0082] It should be emphasized that the term "comprises / comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] The invention will now be described in more detail in relation to the enclosed drawings, in which:

[0084] Fig. 1 schematically shows a first and a second power line of a power grid to which a first power source as well as a first and second enhanced power distribution network are connected, where the first and second enhanced power distribution networks are provided in a region of the power grid, Fig. 2 schematically shows a compensation control device, a compensation handling device, a central clock and a power meter connected to a mobile network as well as the first enhanced power distribution network comprising an inverter and being connected to the compensation handling device,

[0085] Fig. 3 schematically shows a first realization of the compensation handling device,

[0086] Fig. 4 schematically shows a second realization of the compensation handling device,

[0087] Fig. 5 schematically shows a first realization of the compensation control device,

[0088] Fig. 6 schematically shows a second realization of the compensation control device,

[0089] Fig. 7 shows a number of method steps in a first embodiment of a method of handling power compensation being performed by the compensation handling device,

[0090] Fig. 8 shows a number of method steps in a first embodiment of a method of controlling power compensation in the region of the power grid,

[0091] Fig. 9 shows a signal chart of signals exchanged in the first embodiments of the method of handling power compensation and method of controlling power compensation,

[0092] Fig. 10 schematically shows a number of method steps in a second embodiment of the method of handling power compensation,

[0093] Fig. 11 schematically shows a number of method steps in a second embodiment of the method of controlling power compensation in the region of the power grid,

[0094] Fig. 12A - 12B show a signal chart of signals exchanged in the second embodiments of the method of handling power compensation and method of controlling power compensation, Fig. 13A - 1 show signal charts of signals exchanged between the compensation control device, the compensation handling device, a controller for the inverter, the power meter and the central clock in a third embodiment of the methods of handling power compensation and controlling power compensation in the region of the power grid,

[0095] Fig. 14 schematically shows a number of method steps performed by the compensation control device for making the inverters of the enhanced power distribution networks reduce a reactive load of the regions, Fig. 15 schematically shows a number of method steps performed by the compensation control device for making the inverters of the enhanced power distribution networks balance the load of the region,

[0096] Fig. 16 schematically shows a number of method steps performed by the compensation control device for determining a first difference to be used in timing adjustment of the enhanced power distribution networks, and

[0097] Fig. 17 schematically shows a number of method steps performed by the compensation handling device for adjusting the timing of operations of the inverter of the first enhanced power distribution network using the first difference.

[0098] DETAILED DESCRIPTION

[0099] In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular architectures, interfaces, techniques, etc. in order to provide a thorough understanding of embodiments of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known devices, circuits and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0100] Aspects of the present disclosure are directed towards performing power compensation in a three- phase AC power grid or national AC power network.

[0101] Fig. 1 shows a first enhanced power distribution network EPDN1 10 and a second enhanced power distribution network EPDN2 12 as well as a first power source PS1 14, where the first power source 14 is connected to a first end of a first power line PL1 16 and the second enhanced power distribution network 12 is connected to a second end of the first power line 16. The first enhanced power distribution network 10 is in turn connected to a first end of a second power line PL2 18, while the second enhanced power distribution network 12 is connected to a second end of the second power line 18. The first and second power lines 16, 18 are in this case power lines of the power grid. Furthermore, the length of the first power line 16 may be much longer than the length of the second power line 18. Moreover, the first and second enhanced power distribution networks 10, 12 are in this case provided in a region REG 19 of the power grid, which can be provided on a considerable distance from the first power source 14. The region 19 is also connected to the power grid at a connection point CP 17, which as an example is provided on the first power line 16. Thereby the region 19 is also connected to a first power source 14 via the connection point 17. Fig. 2 schematically shows the first enhanced power distribution network EPDN1 10. It comprises a load LD 31, an inverter INV 28, a controller CTRL 33, a power generating system, such as a photovoltaic system PVS 30 that is based on solar panels, and an energy storage system ESS 32, such as a battery system. The inverter 28 has an AC side connected to the second power line 18 and a DC side connected to the photo-voltaic system 30 and the energy storage system 32. Also, the load LD 31 is connected to the second power line 18. The controller 33 controls the operation of the inverter 28. Furthermore, the controller 33 is connected to a compensation handling device CHD 26, which in this case is provided as a User Equipment (UE). The compensation handling device 26 is here provided outside of the first enhanced power distribution network 10. However, it should be realized that it may just as well be provided inside it. It may in fact be combined with the controller 33. The compensation handling device 26 handles power compensation performed by the first enhanced power distribution network. The compensation handling device 26 is comprised in a power compensating arrangement PCA 25. It is also possible that the controller 33 is a part of the power compensating arrangement 25. It should be realized that it is possible that the inverter 28 is also a part of the power compensating arrangement 25. It is additionally possible that the energy storage system 32 and / or photovoltaic system 30 is a part of the power compensating arrangement 25. In the present example, the whole enhanced power distribution network 10 is a part of the power compensating arrangement 25.

[0102] At the connection of the inverter 28 to the second power line 18there is also a power meter PM 24 that is associated with the first enhanced power distribution network 10. It is possible that also the power meter is a part of the power compensating arrangement 25.

[0103] The compensation handling device 26 communicates with a compensation control device CCD 22 and optionally also with the power meter 24. When the compensation handling device 26 is realized as a UE, it may communicate with the power meter 24 and the compensation control device 22 via a mobile network MN 20. For this reason, it is possible that also the power meter 24 is using or comprises a UE.

[0104] It is possible that also the compensation control device 22 employs or uses a UE. However, it may also be server connected to the backbone of the mobile network 20 or in the cloud, i.e., as functionality in a data centre. In fig. 2 there is also a central clock CC 23 connected to the mobile network 20. The compensation handling device 26 and compensation control device 22 may both communicate with the central clock 23. It should be realized that this communication can be made directly using the Internet instead. The central clock 23 may also be a part of the compensation control device 22.

[0105] In the example given above, the compensation handling device 26 is provided as a separate entity that is distinct from the controller 33 of the first enhanced power distribution network 10. However, as an alternative it may be combined with this controller 33. Furthermore, the compensation handling device 26 does not need to be a UE. It can also be provided using a computer in the first enhanced power distribution network 10, which, as is indicated above, may be a part of a computer implementing the controller 33.

[0106] The second enhanced power distribution network 12 may have a similar structure with an inverter and a controller in communication with a compensation handling device. However, it may differ with regard to the photo voltaic system and / or energy storage system, both regarding capacity and provision or existence.

[0107] In this respect it can also be mentioned that it is possible to provide the first enhanced power distribution network without either the photovoltaic system 30 or the energy storage system 32.

[0108] Fig. 3 schematically shows a first realization of the compensation handling device CHD 26. It may comprise a radio circuit RC 39 for implementing mobile communication via the mobile network 20. It may also comprise a processor PR 34 connected to a computer readable-medium or program memory M 36. The computer readable-medium or program memory 36 may comprise a computer program comprising computer program code in the form of a number of computer instructions Cl 38 implementing a compensation handling function. The compensation handling function may thereby be implemented as software. As an alternative it may be provided using hardware, such as through one or more application-specific integrated circuits (ASICs) or field-programmable gate arrays (FPGAs).

[0109] Fig. 4 shows another realization of the part of the compensation handling device 26 that implements the compensation handling function. It comprises a time offset determining element TODE 40, an optional role capability investigating element RCIE 42, an optional timing adjusting element TAE 44 and a role handling element RHE 46. Fig. 5 schematically shows a first realization of the compensation control device CCD 22. It may be provided in the form of a processor PR 48 connected to a computer readable-medium or program memory M 50. The computer readable-medium or program memory 50 may comprise a computer program comprising computer program code in the form of a number of computer instructions Cl 52 implementing the functionality of the compensation control device 22. The functionality of the compensation control device 22 may thereby be implemented as software. As an alternative it may be provided as hardware, such as through one or more application-specific integrated circuits (ASICs) or field-programmable gate arrays (FPGAs).

[0110] Fig. 6 shows another realization of the compensation control device 22. It comprises an optional central clock providing element CCPE 54, a stability investigating element SIE 56, an optional role determining element RDE 57, an optional offset determining element ODE 58, an optional difference determining element DDE 60 and an instruction sending element ISE 62.

[0111] A nationwide AC power network or power grid needs continuous monitoring and active balancing of the amount of energy put into it, and the amount of energy consumed from it, at each moment. Proper control of timing and action in all points of the power grid is essential to stay in energy balance. There is also a need for stabilizing the power grid.

[0112] Furthermore, the first power source 14 may be provided on a long distance from the region 19 with the first and second enhanced power distribution networks 10, 12. Also, the region or rather the totality of loads and sources in the region including loads provided by the enhanced power distribution networks 10, 12 may limit the capacity to transfer power over the first power line 16.

[0113] If the AC power grid could be locally stabilized in the first region 19, then the above-mentioned long-distance power distribution lines could be run full throttle. Such local stabilizing also allows more electric energy to be exported. Also, a larger portion of solar and wind-based energy could be handled in the AC power grid.

[0114] There is thus a need for providing local stabilizing of an AC power grid, which may involve stabilizing frequency and short-term energy fluctuations.

[0115] Beside from stability in frequency and short-term energy over time fluctuations, there are a few more properties that may need to be kept balanced. The ideal situation is that AC-voltage and AC-current are in sync - has the same timing. This is when energy is transferred over the AC power grid from an energy source, such as the first power source 14, to an energy consumer, such as the first enhanced power distribution network 10 and that's it. (No energy bouncing back from the consumer.)

[0116] This may be called a resistor load. This is in most cases the usable energy that is desired to be transferred, which becomes the heat of an oven or the light from a light bulb or the rotational torque of a motor shaft.

[0117] But if there is a coil and / or a capacitor connected, then AC-voltage and AC-current may be out of time with respect to each other. This may cause a significant increase in AC-current amplitude without any more usable energy transferred.

[0118] This may be called a reactive load. This is in most cases the energy buffering of a coil or a capacitor. These types of components grab an amount of energy, hold it for a short while and then return the energy back to the AC power grid. This is energy bouncing back and forth. The transfer of this energy eats up the current conducting ability of electric cables by running current at the wrong timing. This energy is only used for charging and discharging the reactive component.

[0119] Therefore, the transfer of this energy lowers the effective power carrying capacity of the power grid, since power lines have to be designed for the additional reactive power.

[0120] Furthermore, the current caused by a coil is ninety degrees late with respect to the AC-voltage, while the current caused by a capacitor is ninety degrees early with respect to the AC-voltage. Thereby, the current caused by a coil is one hundred and eighty degrees away with respect to the current caused by a capacitor. Thus, these two currents may cancel each other out should they be equal in amplitude. This is another balance to keep in mind.

[0121] Aspects of the present disclosure are directed towards handling one or more of the above- mentioned situations.

[0122] A first embodiment addressing the situations will now be described with reference being made to fig. 7, 8 and 9, where fig. 7 shows a number of method steps in a method of handling power compensation being performed by the compensation handling device 26, fig. 8 shows a number of method steps in a method of controlling power compensation in the region 19 of the power grid being performed by the compensation control device 22 and fig. 9 shows a signal chart of signals exchanged between the compensation handling device 26, the compensation control device 22, the central clock 23 and the controller 33 of the first enhanced power distribution network 10.

[0123] The inverter 28 of the first enhanced power distribution network 10 may be capable to take on or operate in at least one of a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role, where the at least one active compensating role may comprise an active power load role and an active power source role. The roles may additionally be further expanded. For instance, the coil mimicking roles may comprise a first coil mimicking role in which a coil is mimicked in four quadrants, a second coil mimicking role in which a coil is mimicked in two energy supplying quadrants and a third coil mimicking role in which a coil is mimicked in two energy drawing quadrants. The capacitor mimicking roles may comprise a first capacitor mimicking role in which a capacitor is mimicked in four quadrants, a second capacitor mimicking role in which a capacitor is mimicked in two energy supplying quadrants and a third capacitor mimicking role in which a capacitor is mimicked in two energy drawing quadrants. An energy supplying quadrant may be a quadrant where the product of current and voltage at the enhanced power distribution network is negative, while an energy drawing quadrant may be a quadrant where the product of current and voltage at the enhanced power distribution network is positive. The second enhanced power distribution network 12 may have similar roles that the corresponding inverter is able to take on.

[0124] The operation may start through the time offset determining element 40 of the compensation handling device 26 obtaining a time TO of the central clock 23, S100, X100. This obtaining may be made through fetching or receiving. The central clock time TO may, as is shown in fig. 9, be obtained directly from the central clock 23 through sending a request REQ via the radio circuit 39 for a time of the central clock, X100A, and receiving such a time TO as a response also via the radio circuit 39, X100B, for instance in an acknowledgement ACK comprising the time TO. As an alternative the time offset determining element 40 may obtain the time TO of the central clock 23 from the compensation control device 22.

[0125] Thereafter the time offset determining element 40 of the compensation handling device 26, which is located at the first enhanced power distribution network 10, obtains the time of a crossing of a reference level of a phase at the first enhanced power distribution network 10, S102. The reference level may with advantage be a level of one of the phases of the voltage at the first enhanced power distribution network 10. The voltage level may be any voltage level of the voltage waveform. However, it is with advantage a zero-voltage level, i.e. where the zero voltage level is crossed in the waveform. Only one crossing per period may be used. Therefore, the crossing may be a positive or a negative crossing of the zero-voltage level, where a positive crossing is a crossing when the waveshape has a positive slope and a negative crossing is a crossing when the waveshape has a negative slope. It may be preferred to use the positive crossing.

[0126] Also the obtaining of a time of a crossing of a reference level may be made through fetching or receiving. For instance, the compensation handling device 26 may query the power meter 24 for the time that the phase crosses the voltage level with a positive slope, which power meter 24 may go on and measure this time and respond to the query with the measured time. Alternatively, the compensation handling device 26 may ask the controller 33, for the same thing. As yet another possibility, which is shown in fig. 9, the time offset determining element 40 may collect X102 measurements from the inverter 28 via the controller 33 and determine the time of crossing with a positive slope based on these voltage measurements X104. The time offset determining element 40 may thus send a request REQ to the controller 33 for phase measurements, X102A, and receive such measurements, preferably time-stamped, as a response, X102B, which response may be an acknowledgement ACK comprising the phase measurements. The time offset determining element 40 may then analyse the measurements and determine the time of the positive crossing of the phase reference level, X104. Thereafter the time offset determining element 40 determines a first time offset T 1 from the central clock 23 based on the crossing of the reference level, S104, X105. The first time offset T 1 may as an example be determined as the difference between the time TO of the central clock and the time of the crossing of the reference level, for instance the time of the positive crossing of the reference level. It should here be realized that it is possible to determine the first time offset T 1 in the same way based on measurements received from the power meter 24 instead. It is optionally also possible that the time offset determining element 40 informs the compensation control device 22 of the first time offset T 1 .

[0127] The same types of determination may be made on behalf of the second enhanced power distribution network 12. The compensation handling device associated with this network 12 may also inform the compensation control device 22 about an own determined first time offset.

[0128] The stability investigating element 56 of the compensation control device 22 may investigate the stability of the power grid in the region 19, S200, X106. This may involve requesting current and voltage measurements from all power meters in the region 19, including power meters 24 for the first and second enhanced power distribution networks 10, 12. It may also or instead involve obtaining such measurements from the enhanced power distribution networks 10, 12 themselves, for instance via corresponding compensation handling devices 26.

[0129] The collected data may then be used to investigate the stability of the region 19, which stability investigation may involve investigating the phase difference between the current and voltage of the region and determine if the region acts as reactive load based on the phase difference, for instance as a capacitive or inductive load, as well as to determine if the region acts as an active load or source based on the phase difference, where the current of the region is the sum of currents into and out of the region. The region is an active load if the currents are in phase with the voltage, an active source if the currents are one-hundred and eighty degrees out of phase with the voltage, an inductive reactive load if the currents lag ninety degrees behind the voltage and a capacitive reactive load if the current is ninety degrees ahead of the voltage. Additionally, the investigation may involve investigating the amplitude of the current of the region.

[0130] The situation described above is an ideal situation. In reality, some combination is likely to be seen. The region can thus be an active load or active source at the same time as it is a capacitive or inductive load.

[0131] If the current is 0 degrees off voltage, then the region is an active load, if the current is 180 degrees out of phase with the voltage then the region is an active source, if the current is 1 - 89 degrees ahead of the voltage then the region is a capacitive reactive load and an active load, if the current is 90 degrees ahead of the voltage then the region is a capacitive reactive load and if the current is 91 - 179 degrees ahead of voltage then the region is a capacitive reactive load and an active source. If the current is 1 - 89 degrees behind the voltage then the region is an inductive reactive load and an active load, if the current is 90 degrees behind the voltage then region is a inductive reactive load and if the current is 91 - 179 degrees behind the voltage then region is an inductive reactive load and an active source.

[0132] The role determining element 57 may also investigate activities that improve the stability of the region or grid. This may be an investigation of which of the roles the inverters of the different enhanced power distribution networks that can be used for improving the grid stability, such as to reduce the reactive load if the region acts as such and to reduce the active source or load if the region acts as such a source or load. If the region acts as a reactive load, the inverters can be made to mimic capacitors, if the region acts as a capacitive load the inverters can be made to mimic coils, if the region acts as an active load the inverters may be made to act like active sources and if the region acts as an active source the inverters may be made to act like active loads. The ability of the inverters to occupy these roles may also be investigated. The result of the investigation may be a determination of at least one role that each inverter is to operate according to, where additionally the role may be a role within the role acting capability of the inverter. The investigating of a role for an inverter may additionally involve determining a current amplitude needed to apply at + or - 90 degrees relative to voltage timing to bring sum of currents in phase with voltage timing and determine what timing to use, + or - 90 degrees relative to the voltage timing (the time of the central clock TO modified with the first time offset T1).

[0133] The compensation control device 22 then sends an instruction to at least some of a number of compensation handling devices, each being associated with a corresponding enhanced power distribution network, to make the inverter of the corresponding enhanced power distribution network act according to at least one of the roles for stabilising the power grid in the region 19, S202. For instance, the instruction sending element 62 of the compensation control device 22 may send instructions to the compensation handling devices 26 associated with the enhanced power distribution networks 10, 12 in the region 19, which instructions are instructions to make the corresponding inverters act according to at least one role within its corresponding role acting capability that improves the grid stability. As can be seen in fig. 9, this also involves sending an instruction RAI (Role Acting Instruction) X108 to the compensation handling device 26 associated with the first enhanced power distribution network 10, which instruction is an instruction to make the inverter 28 act in at least one role that helps in stabilising the grid.

[0134] The compensation control device 22 may have knowledge of the roles the inverters of the enhanced power distribution networks are capable of acting, for instance through having been informed by the corresponding compensation handling devices or via knowledge about if the corresponding enhanced power distribution networks comprise photovoltaic systems and / or energy storage systems. In this case the instruction to a compensation handling device may also be an instruction to make the corresponding inverter act in a role that it is capable of occupying. Alternatively, the compensation control device 22 may have no knowledge of the capability, but may nevertheless send an instruction in the hope that the corresponding inverter is capable to act in the role.

[0135] The compensation handling devices then receives the instructions and act upon them if the corresponding inverters have the capability. For instance, the instruction to act in at least one of the roles from the compensation control device 22 may be received via the radio circuit 39 by the role handling element 46 of the compensation handling device 26 associated with the first enhanced power distribution network 10, S106, X108. If the inverter 28 is capable to act according to the at least one role, which may be known based on investigations about the status of the inverter 28, the status of the photovoltaic system 30 and the status of the energy storage system 32, the role handling element 46 orders the inverter 28 to act according to the at least one instructed role, S108, which may be done through sending an instruction to the controller 33 to control the inverter 28 to operate according to the role, X110. The controller 33 then controls the inverter 28 to act in the instructed role and in this control a timing is used which is based on a current time of the central clock TO adjusted with the first time offset T 1 . The acting in the at least one instructed role is thus performed using a timing that is based on the central clock adjusted with the first time offset T 1 . The timing may more particularly be the time TO of the central clock plus the first time offset T 1 . This type of control may be performed in all enhanced power distribution networks in the region 19.

[0136] Each inverter, when acting in the at least one role, thus applies a timing that is based on the central clock adjusted with an individual first time offset, which individual first time offset is a difference in time between the time of a crossing of a reference level of a phase at the corresponding enhanced power distribution network and the time of the central clock.

[0137] The timing used when acting in at least one role can be considered to be an ordered timing, which ordered timing is thus a timing that is based on the central clock 23 adjusted with the first time offset T 1 . The ordered timing may be a timing that is the first time offset T 1 added to the time TO of the central clock 23.

[0138] An unadjusted active power load role may be provided through a phase current that is in phase with the corresponding phase voltage, an unadjusted power source role may be provided through a phase current that is displaced one hundred and eighty degrees from the corresponding phase volage, an unadjusted coil mimicking role may be provided through a phase current that is ninety degrees after the corresponding phase voltage and an unadjusted capacitor mimicking role may be provided through a phase current that is ninety degrees before the corresponding phase voltage.

[0139] This means that if the role is to be timed with the ordered timing, the power load role may be operated with the phase current being timed at the timing of the corresponding phase voltage adjusted with the ordered timing, the power source role may be operated with the phase current being timed with a timing that is displaced by one-hundred and eighty degrees from the corresponding phase voltage adjusted with the ordered timing, the coil mimicking role may be operated with the phase current being timed with a timing that is ninety degrees after the timing of the corresponding phase voltage adjusted with the ordered timing and the capacitor mimicking role may be operated with a phase current that is ninety degrees before the corresponding phase voltage adjusted with the ordered timing.

[0140] Through the different enhanced power distribution networks acting in a concerted way that is based on the individual first time offsets, it is then possible that the region gets stabilized.

[0141] By communicating correct timing and steering to controlled inverters, it is possible to improve the different types of energy balances needed within the power grid. This could replace the stability (flywheel energy buffering) lost when large energy plants are shut-down and replaced by many small wind and solar power-plants.

[0142] Moreover, the above-mentioned aspects can improve balancing of reactive loads so that the electric current in the cables of the power grid may be kept at minimum. With good balancing of the region 19, the first power line 16 from the first power source 14 to the region 19 can be run at full throttle. With good balancing, a greater portion of wind and solar power plants can be handled in the AC power grid.

[0143] A second embodiment addressing the situations will now be described with reference being made to fig. 10, 11, 12A and 12B, where fig. 10 shows a number of method steps in a method of handling power compensation being performed by the compensation handling device 26, fig. 11 shows a number of method steps in a method of controlling power compensation in the region 19 of the AC power grid being performed by the compensation control device 22 and fig. 12A and 12B show a signal chart of signals exchanged between the compensation control device 22, the power meter 24, the compensation handling device 26 and the controller 33 of the first enhanced power distribution network 10.

[0144] As before, the inverters of the first and second enhanced power distribution network 10, 12 are capable to take on a number of roles, which roles have been previously described.

[0145] In this embodiment the compensation control device 22 provides the time TO of the central clock to the compensation handling devices. For this reason, the central clock providing element 54 of the compensation control device 22 may include the central clock. However, it should be realized that as an alternative it may communicate with an external central clock in order to get the time.

[0146] Thereby, the operation may start through the central clock providing element 54 of the compensation control device providing a time TO of the central clock to each compensation handling device in the region 19, S400, which may be done through sending the time TO to each compensation handling device in the region 19 including the compensation handling device 26 of the first enhanced power distribution network 10. Thereby this compensation handling device 26 also obtains the time TO of the central clock, S300, which may be done through the time offset determining element 40 receiving it from the compensation control device 22 via the radio circuit 39, X200.

[0147] Thereafter the time offset determining element 40, obtains the time of crossing a phase reference level, which may be a positive crossing of the phase reference level. In this embodiment this is done through collecting voltage measurements, S302, determining a time of crossing, such as a positive crossing, of the phase reference level based on the voltage measurements, S304, and determining the first time offset T 1 based on the time of the central clock and the time of the crossing of the phase reference level, S306. The first time offset T 1 is with advantage determined as the difference between the time of positive crossing of the phase reference level and the time TO of the central clock. As before it is possible that a negative crossing is used instead. The voltage level may again be the zero-voltage level, although other levels are of course also possible. It is also possible to obtain the voltage from the inverter 28 instead.

[0148] In this embodiment the time offset determining element 40 collects voltage measurements from the power meter 24, S302, X202, which may involve sending a request REQ to the power meter 24 for phase voltage measurements via the radio circuit 39, X202A, and receiving such measurements, preferably time-stamped, as a response X202B, for instance included in an acknowledgment ACK. The time offset determining element 40 may then analyse the voltage measurements and determine the time of positive crossing of the phase reference level, S304, X204, which may again be a positive crossing of the zero-voltage level. Thereafter the time offset determining element 40 determines the first time offset T 1 based on the positive crossing of the phase reference level and the time TO of the central clock, S306, X206. As was mentioned above, the first time offset T 1 may as an example be determined as the difference between the time TO of the central clock and the time of the positive crossing of the reference level, which level may again be a zero level of a voltage phase. After having determined the first time offset T1 , the time offset determining element 40 provides it to the compensation control device 22, S308, which may be done using the radio circuit 39. It thus informs the compensation control device 22 of the first time offset T 1 , X208.

[0149] The same types of determinations may be made by a compensation handling device associated with the second enhanced power distribution network 12. This compensation handling device may also inform the compensation control device 22 about an own determined individual time offset.

[0150] The first time offset T 1 from the compensation handling device 26 associated with the first enhanced power distribution network 10 and the other individual time offsets from the other compensation handling devices associated with the other enhanced power distribution networks in the region 19 are received by the offset determining element 58 of the compensation control device 22, which offset determining element 58 thereby obtains individual time offsets from each of the compensation handling devices in the region 19, S402. Alternatively, they may be fetched. It then goes on and determines individual modified time offsets for each of the enhanced power distribution networks, S404, X210. In respect of the compensation handling device 26 associated with the first enhanced power distribution network 10 it thus determines a modified first time offset TT. The modified time offset TT may be determined as a fixed number n of full periods, such as 100 periods, of the waveform, which number n is then added to or subtracted from the individual time offsets. Thereby it may also be added to or subtracted from the first time offset T 1 . Thus, the modified first time offset TT may be a time where a number of full periods of the phase has been added to the first time offset T 1 . The offset determining element 58 then provides the individual modified time offsets to the corresponding compensation handling devices, S406. As can be seen in fig. 12A, the modified first time offset TT is sent to the compensation handling device 26 associated with the first enhanced power distribution network 10, X212, which modified first time offset TT is received by the timing adjusting element 44 of the compensation handling device via the radio circuit 39, S310. The timing adjusting element 44 then adjusts the timing that is to be used into the modified first time offset TT.

[0151] Before the inverter 28 of the first enhanced power distribution network 10 will act according to any of the previously described roles, the role capability investigating element 42 of the compensation handling device 26 may investigate the support capacity of the first enhanced power distribution network 10, S312. It may do this through connecting to the controller 33 and obtaining data about the capacity of the inverter 28, the energy storage system 32 and the photovoltaic system 30, X214. This obtaining may be made through fetching or receiving. The capability investigating element may for instance send a query about the energy storage capacity of the inverter 28, the energy storage system 32 and the energy supply capacity of the photovoltaic system 30, inverter 28 and energy storage element 32, QUER X214A, and receive a response RES, X214B, with information of these capabilities. The role capability investigating element 42 may then determine which roles the inverter 28 is capable of taking on based on the support capacity, S314, X216.

[0152] For instance, if there is a surplus of capacity in the photovoltaic system 30 or fully or well loaded batteries in the energy storage system 32, then it may be possible to act as source but not as a load. An energy storage system 32 with batteries having a low battery charge level together with a photovoltaic system 30 with no surplus power capacity may not be able to act as a source but can with advantage act as a load.

[0153] After having determined the capability, the role capability investigating element 42 of the compensation handling device 26 associated with the first enhanced power distribution network 10 informs the compensation control device 22 about the role acting capability RAC via the radio circuit 39, S316, X218. It thus informs the compensation control device 22 of the roles the inverter 28 is capable of occupying.

[0154] The role determining element 57 of the compensation control device 22 may receive this type of information from all the enhanced power distribution networks of the region 19. The compensation control device 22 may thus receive information from the compensation handling devices of the roles the corresponding inverters are capable of occupying.

[0155] The stability investigating element 56 of the compensation control device 22 may then investigate the stability of the power grid in the region 19, S410, X220, which may be done in the same way as in the first embodiment.

[0156] The stability investigation may again involve investigating if the region 19 acts as reactive load or source, for instance as a capacitive or inductive load or source as well as to determine if the region acts as an active load or active source. The role determining element 57 may also determine activities or roles that improve the stability of the region or grid, such as activities or roles that reduce the load, S412, X221. What these activities or roles may be will be described in more detail later on. However, the activities that are performed by the inverters of the enhanced power distribution networks are within these capabilities. After the role determining element 57 has determined the activities to be performed by the enhanced power distribution networks 10, 12 in the region 19 for stabilising the grid, the instruction sending element 62 sends instructions to the compensation handling devices to act according to at least one role within their individual role acting capabilities, S414. Thus, the instruction to act according to at least one role is an instruction to act in at least one role that the corresponding inverter is capable of occupying.

[0157] These instructions are then received by the compensation handling devices, including a role handling instruction RAI received by the compensation handling device 26 associated with the first enhanced power distribution network 10, S318, X222, where the compensation handling device 26 receives these instructions via the radio circuit 39. The role handling element 46 of this compensation handling device 26 then instructs the inverter 28 of the first enhanced power distribution network 10 to act in the instructed role using the modified first time offset TT, S320. which role is within the role acting capability. The instructing is done through sending the instruction to the controller 33, X224, which then controls the inverter 28 and possibly also the energy storage system 32 and / or photovoltaic system 30 such that the instructed role is performed. In the performing of the activity a timing is also used that is based on the time TO of the central clock adjusted with the modified first time offset TT. The used timing may be the time TO of the central clock to which the modified first offset TT has been added.

[0158] The second embodiment can also be described in the following way.

[0159] 1. A (set) a wall clock, TO, is distributed, which is a free running clock that shall be present at all enhanced power distribution networks in the power grid. As an example, TO may be set seldom, maybe once a day. Furthermore, Resolution and accuracy could be at least 100 microseconds.

[0160] TO at the different enhanced power distribution networks all tell the same time.

[0161] 2. A theoretical reaching of a phase reference level, such as a positive zero crossing of the phase R, may be monitored in the period of the phase waveshape. (The three phases are R S T in the AC power grid.). The period may for instance be 20 ms, which corresponds to a frequency of 50 Hz.

[0162] 3. A time offset is then determined, which time offset is unique for each enhanced power distribution network in the AC power grid and is measured as the offset needed to sync TO in time with the actual reaching of the phase reference level of the phase R, here positive zero crossing of phase R, in the point in question.

[0163] 4. The time offsets, including the first time offset T1 , are sent to the compensation control device 22.

[0164] 5. All interesting points (all enhanced power distribution networks) in the region 19 of the power grid may have a unique time offset. The time offset is known locally for each point and at the compensation control device 22.

[0165] 6. The various time offsets, including the first time offset T 1 , may then be maintained and updated from the compensation control device 22.

[0166] 7. Modified time offsets, including a modified first time offset TT for the first enhanced power distribution network 10, may then be sent from the compensation control device 22 to the compensation handling devices associated with the enhanced power distribution networks. The correct timing may be many whole periods (20 milliseconds off for a 50 Hz power grid).

[0167] 8. The compensation control device 22 then asks the compensation handling devices what roles the inverters of the corresponding enhanced power distribution networks can occupy at the moment.

[0168] 9. The individual compensation handling devices then list what roles the corresponding inverter can act in at the moment.

[0169] To each role, it may additionally provide a measure how fast it can be switched on, a measure of how fast it can be switched off and a measure of how the role can be throttled, like:

[0170] Minimum power, Maximum power, fraction of Maximum power resolution.

[0171] Roles:

[0172] Power source, in phase with voltage - typically a solar panel.

[0173] Power load, in phase with voltage - typically a battery charger.

[0174] Power source, mimic capacitor during power source or energy supplying quadrants. Power load, mimic capacitor during power load or energy drawing quadrants.

[0175] Power source, mimic coil during power source or energy supplying quadrants.

[0176] Power load, mimic coil during power load or energy drawing quadrants.

[0177] 10. The compensation control device 22 asks the compensation handling devices to make the corresponding inverter take on a certain role. The compensation handling devices or even the controllers for the inverters may also locally calculate the timing for the role taken on, which timing is based on the local version of the central clock TO and the modified time offset TT.

[0178] 11 . Furthermore, the modified time offset may be dynamically updated from the compensation control device as frequency / phase of whole power grid is slowly drifting. But for quick changes each compensation handling device may keep timing as provided by a local version of the central clock plus the modified time offset. Thereby, several inverters may stay at a correct timing and provide stability to the AC power grid.

[0179] 12. Roles may be dynamically updated as energy needed / available changes over time.

[0180] A third embodiment addressing the situations will now be described with reference being made to Fig. 13A - 1, which show signal charts of signals exchanged between the compensation control device 22, the compensation handling device 26 associated with the first enhanced power distribution network 10, the power meter 24, the central clock 23 and the controller 33.

[0181] The central clock providing element 54 of the compensation control device 22 requests a central clock (wall clock) from a suitable source, such as a clock reference in Germany, X300, which may be done through sending a request REQ for the central clock, x300A, and receiving an acknowledgement ACK, X300B. which acknowledgement comprises data of the time of the central clock 23. The central clock providing element 54 then determines the time TO of the central clock 23 based on the received clock data, X302, such that now there is a correct central clock TO at the compensation control device 22.

[0182] This may be repeated at suitable interval depending on quality of an oscillator that is used for stepping TO at the compensation control device 22. The stability investigating element 56 of the compensation control device 22 may then poll the power meters associated with all clients in the region 19, including all enhanced power distribution networks 10, 12 to get voltage measurements, current measurements and measurements of the phase difference between the voltage and current at the corresponding clients. It thus polls, X304, the power meter 24 of the first enhanced power distribution network 10, which may involve sending a request REQ, for a list of data from the power meter 24, X304A, which power meter data PMD comprises voltage, current and the phase between voltage and current. The power meter 24 may then respond, X304B, with an ACK comprising the list of power meter data PMD. This may be repeated at suitable interval to keep a relevant model of power grid status within the compensation control device 22.

[0183] Each compensation handling device may have an identity CHDID, such as an IMEI (International Mobile Equipment Identity), an ICCID (Integrated Circuit Card Identification Number) comprising a phone number or even an Internet Protocol (IP) address. The compensation handling device can then be reached via this identity. Each compensation handling device may additionally find out the identity of the closest power meter it sits behind. For instance, the compensation handling device 26 associated with the first enhanced power distribution network 10 may have such an own identity and may also find out the identity of the power meter 24 for the first enhanced power distribution network 10. The compensation handling device 26 may request the meter identity Ml from the power meter 24, X306A and receive and ACK comprising this meter identity Ml, X306B. Alternatively, the meter identity Ml may be hardcoded within the inverter 28 placed there at installation time, in which case the compensation handling device 26 may ask for the power meter identity from the controller 33.

[0184] The compensation handling device 26 may then present itself and the first enhanced power distribution network 10 to the compensation control device 22. The presentation may be made in a message comprising a report REP comprising the power meter identity Ml and the own identity CHDID, X308. The message may additionally include a request REQ for the central clock TO. It is possible that all compensation handling devices in the region sends such messages.

[0185] The central clock providing element 54 of the compensation control device 22 may then send the central clock timing TO as a response RES, X310, which is thus sent to all compensation handling devices including the compensation handling device 26 associated with the first enhanced power distribution network 10. The stability investigating element 56 of the compensation control device 22 may then link the power meter identity Ml to compensation handling device identity CHDID, X312, which may be done for each enhanced power distribution network. Note, there may be many enhanced power distribution networks behind the same power meter and each such enhanced power distribution network may be associated with a corresponding compensation handling device.

[0186] Each compensation handling device then continues and determines a corresponding time offset. In the present example, the compensation handling device 26 associated with the first enhanced power distribution network 10 determines the first time offset T 1 . This involves the time offset determining element 40 collecting measurements from the inverter 28, X314, which involves querying QUER the controller 33 for measurements from the inverter 28, X314A, and receiving such measurements as a response RES X314B. The time offset determining element 40 of the compensation handling device 26 then determines the actual time of the positive zero-crossing of a phase R, X316, and then determines the first time offset T 1 based on this time and the time TO of the central clock, X317. The determining may more particularly be the determining of a difference in time of the actual zero crossing and the time when the zero crossing should have taken place according to the central clock, i.e. when it should have taken place if there were no delay. Put differently the first time offset T 1 may be the time from an expected positive zero transmission at TO until an actual positive zero transmission is seen by the inverter 28. The first time offset T 1 may be a value in the interval 0 - 20 ms.

[0187] The compensation handling device 26 then sends the first time offset T 1 to the compensation control device 22, X318. The knowledge about the voltage timing as seen at the point of the inverter 28 of the first enhanced power distribution network 10 is in this way brought to the compensation control device 22.

[0188] The time offset in respect of all compensation handling devices is in this way noted by the compensation control device 22 and based on these individual time offsets, a modified individual time offset is then determined for each enhanced power distribution network.

[0189] The determining of a modified first time offset TT for the first enhanced power distribution network 10, X320, may involve refining the first time offset T1, X320A. The offset determining element 58 of the compensation control device 22 may know the location of the power meter 24 and based on this it can deduce the location of the first enhanced power distribution network 10. This knowledge may be used to further refine the first time offset T 1 . Thereafter the actual determination of the modified time offset is done, X320B, which may be done using the refined or non-refined first time offset.

[0190] The compensation handling device 26 did determine the time offset from an expected positive zero crossing of voltage at R phase until a real zero crossing. This provides knowledge about where within a period of the sine waveshape of the phase voltage that event occurs, which period is 20 ms for a frequency of 50 Hz.

[0191] However, the power grid timing may have been running at slightly higher or lower frequency for some time. Accumulating a timing error of many 20 ms (50Hz) period times. The offset determining element 58 of the compensation control device 22 may know about this drift and calculate the modified first time offset TT based on this knowledge about frequency variations. For instance, the modified first time offset TT may be determined as:

[0192] TT=T1+X*Tper, where Tper is the period of the sine waveshape of the phase voltage and X is an integer that depends on the frequency variations. X may more particularly represent the number of periods that the first time offset T 1 may slip away from the central clock TO. X can be positive or negative.

[0193] After having determined a modified time offset T for each enhanced power distribution network, the compensation control device 22 sends each modified time offset to the corresponding compensation handling device.

[0194] For instance, it sends the modified first time offset TT to the timing adjusting element 44 of the compensation handling device 26 associated with the first enhanced power distribution network 10, X322 to which the compensation handling device may respond with an ACK, X324. The timing adjusting element 44 then adjusts the timing that is to be used into the modified first time offset TT.

[0195] Each compensation handling device also determines the role capability of the inverter in the corresponding enhanced power distribution network and informs the compensation control device 22 about this capability. For instance, the role capability investigating element 42 of the compensation handling device 26 associated with the first enhanced power distribution network 10 may investigate the support capacity of the first enhanced power distribution network 10. It may do this through connecting to the controller 33 and obtaining data about the capacity of the inverter 28, the energy storage system 32 and the photovoltaic system 30, X326. It may for instance send a request REQ of the energy storage capacity of the inverter 28 and energy storage system 32 and the energy supply capacity of the photovoltaic system 30, inverter 28 and energy storage system 32. X326A, and receive a response with information of these capabilities, X326B, for instance in the form of an ACK. The compensation handling device 26 then determines which roles the inverter 28 is capable of taking on based on the collected data, X328.

[0196] As an example, the roles may comprise one or more of the roles:

[0197] Power source, resistor power, one hundred and eighty degrees out of phase with voltage. # of W, kW, MW, GW.

[0198] Power load, resistor load, in phase with voltage.

[0199] # of W, kW, MW, GW.

[0200] Power source, mimic capacitor during power source quadrants.

[0201] # of VA, kVA, MVA, GVA.

[0202] Power load, mimic capacitor during power load quadrants.

[0203] # of VA, kVA, MVA, GVA.

[0204] Mimic capacitor during all four quadrants

[0205] # of VA, kVA, MVA, GVA

[0206] Power source, mimic coil during power source quadrants.

[0207] # of VA, kVA, MVA, GVA.

[0208] Power load, mimic coil during power load quadrants.

[0209] # of VA, kVA, MVA, GVA.

[0210] Mimic coil during all four quadrants,

[0211] # of VA, kVA, MVA, GVA

[0212] To each role, tell a measure how fast it can be switched on. (Like: 20ms, 100ms, 30s, 2min, 48h, ...)

[0213] To each role, tell a measure how fast it can be switched off. (Like: 20ms, 100ms, 30s, 2min, 48h, ...)

[0214] To each role, tell a measure how a power role can be throttled. (Min, Max, resolution as a fraction of Max)

[0215] To each role, tell how it can be ramped-up / ramped-down.

[0216] (Min, Max, ramp-up speed, ramp-down-speed)

[0217] After having determined the capability, the role capability investigating element 42 of the compensation handling device 26 associated with the first enhanced power distribution network 10 informs the compensation control device 22 about the role acting capability RAC, X330, and the compensation control device may respond with an ACK, X332.

[0218] As is mentioned above, the compensation control device 22 may receive this type of information from all the enhanced power distribution networks of the region.

[0219] The role determining element 57 of the compensation control device 22 may then determine roles that the inverters of the enhanced power distribution networks are to occupy.

[0220] In order to determine such roles, the stability investigating element 56 of the compensation control device 22 may poll power meters and receive information of the phase difference the between voltage and current at the different clients of the power grid. Also the compensation handling devices may provide information about voltage timing as seen at the corresponding Inverter.

[0221] This information may be used by the stability investigating element 56 to obtain or get an overall central awareness of the stability of the grid, X334. This overall central awareness may then be communicated to the role determining element 57. Based on this central awareness and the capability that each enhanced power distribution network has, the role determining element 57 of the compensation control device 22 then determines one or more role that one or more of the inverters of the enhanced power distribution networks are to occupy, X336.

[0222] With regard to the inverter 28 of the first enhanced power distribution network 10, the instruction sending element 62 of the compensation control device 22 then sends an instruction to implement one or more of the roles, i.e. a role implementing instruction (RII), which instruction is thereafter sent to the first compensation handling device 26 associated with the first enhanced power distribution network 10, X338. The compensation handling device 26 may then respond to this instruction with an ACK, X340.

[0223] As an example the instruction can include one or more of the instructions described below: Mimic Capacitor, amplitude 8 A, start at (TO + TT), ramp-up during 5 seconds, continue forever. Mimic Coil, amplitude 12 A, start at (TO + TT), ramp-up during 0 seconds, continue forever. Mimic power source, 12kW, start at (TO + TT), ramp-up during 30 seconds, continue forever. Mimic power load, 6kW, start at (TO + T1), ramp-up during 600 milli seconds, continue for 20 sec then ramp down during 2 seconds.

[0224] Mimic Capacitor, amplitude 6 A, run power source quadrants (as you are a power source), start immediately, continue forever.

[0225] Mimic Capacitor, amplitude 6 A, run power load quadrants (as you are a power load), start immediately, continue forever.

[0226] Mimic power source, 10kW, start at (TO + T1), ramp-up during 600 milli seconds, continue forever.

[0227] Thereafter the compensation control device 22 and the compensation handling devices may operate in a number of loops, i.e. in a re-occurring sequence of events.

[0228] In a first loop, the compensation control device 22 has a local clock that implements the central timing of the central clock TO. It may be a binary counter being fed a tick signal that makes it count- up for each tick. The tick may be generated by an oscillator that is meant to keep a steady frequency.

[0229] The register may be set to a correct value (the clock is set) and then the tick makes the register implement a clock, that is the time TO of the compensation handling devices or inverters.

[0230] Depending on the oscillator ability to keep the correct frequency, the TO may have to be corrected over time.

[0231] The first loop repeatedly checks that there is a correct TO and updates this TO if needed.

[0232] Put differently, the central clock providing element 54 of the compensation control device 22 requests the central clock from the central clock source 23, X342, which may involve sending a request REQ for the central clock, x342A, and receiving an acknowledgement ACK comprising the central clock, X342B.

[0233] Then the central clock providing element 54 of the compensation control device 22 determines the time TO of the central clock based on the received clock data, X344, such that now there is a correct central clock TO at the compensation control device 22. This is followed by computing the delay, X346, which delay depends on the local oscillator quality and conditions.

[0234] Then a return to the beginning of the loop is made, X348, when the delay has reached delay threshold, which may be a threshold of for instance 24 hours.

[0235] The second loop describes a similar operation in the compensation handling device 26 associated with the first enhanced power distribution network 10.

[0236] The compensation handling device 26 or the controller 33 may have a local clock that implements TO. It may be a binary counter fed a tick signal that make it count-up for each tick. The tick is generated by an oscillator that is meant to keep a steady frequency.

[0237] The register is set to a correct value (the clock is set) and then the tick makes the register implement a clock, that is the local TO.

[0238] Depending on the oscillator ability to keep the correct frequency, the local TO may have to be corrected over time.

[0239] This second loop repeatedly checks that there is a correct local TO and updates this local TO if needed.

[0240] Put differently the compensation handling device 22 requests the central clock from the compensation control device, X350, which may involve sending a request REQ for the central clock TO, x350A, and receiving an acknowledgement ACK with the central clock TO, X350B.

[0241] Then the compensation handling device 26 determines the time of the central clock TO based on the received clock data, X352, such that now there is a correct local clock TO at the compensation handling device 26. This is followed by computing the delay, X354, which delay depends on the local oscillator quality and conditions. Then a return to the beginning of the loop is made, X356, when the delay has reached a delay threshold. As an example the delay threshold may be 24 hours.

[0242] If the compensation handling device 26 is combined with the controller 33 and a correcting of the local clock TO is needed, care must be taken to slowly adapt to the correct setting in a way that other logic is kept undisturbed by this correction. Meaning, it is not desirable to skip or pass twice any TO counter values, because that would risk incorrect waveform rendering in power electronics.

[0243] The compensation control device 22 is constantly receiving information about the conditions in different points of the power grid.

[0244] The third loop shows how the time offset determining element 40 recurringly determines the first time offset T1 and the role capability investigating element 42 recurringly determines the role acting capability in the compensation handling device 26 associated with the first enhanced power distribution network 10.

[0245] The voltage timing is thus repeatedly being obtained by the compensation handling device 26. This is the first time offset T 1 being determined as seen at the inverter 28.

[0246] This involves the time offset determining element 40 of the compensation handling device 26 collecting measurements from the inverter 28, X358, which involves requesting REQ measurements of the inverter 28 from the controller 33, X358A, and receiving such measurements as a response RES, X358B. The time offset determining element 40 of the compensation handling device 26 then determines the actual time of the positive zero-crossing of the phase R, X360, and then determines the first time offset T 1 based on this time and the time of the central clock To, X361.

[0247] The time offset determining element 40 of the compensation handling device then investigates if the first time offset has changed since the previous investigation, X362, and if it has it sends the new first time offset T 1 to the compensation control device 22, X364, to which the compensation control device 22 may respond with an ACK, X366.

[0248] Thus, if the newly determined first time offset differs (significantly) from the previously determined first time offset, then this new first time offset is sent to the compensation control device 22.

[0249] Furthermore, if a long time has elapsed since the last sending of any information to the compensation control device 22, such as a time that is longer than a defined time out interval, a heartbeat may be sent to indicate that the compensation handling device 26 is still operational, and there is nothing new to report. The role capability investigating element 42 of the compensation handling device 26 also recurringly determines the role acting capability of the inverter 28.

[0250] It may do this through connecting to the controller 33 and obtaining data about the capacity of the inverter 28, the energy storage system 32 and the photovoltaic system 30, X368. It may for instance send a query QUER about the energy storage capacity of the inverter 28 and energy storage system 32 and the energy supply capacity of the photovoltaic system 30, inverter 28 and energy storage system 32, X368A, and receive a response RES with information of these capabilities X368B. The role capability investigating element 42 of the compensation handling device 26 then determines which roles the inverter 28 is capable of taking on based on the collected data, X370.

[0251] It also investigates if the roles have changed since the last role determination, X371.

[0252] If the roles have changed, the role capability investigating element 42 of the compensation handling device 26 then sends and update of the role acting capability RAC to the compensation control device, X372, to which the compensation control device 22 may respond with an ACK, X373.

[0253] The compensation handling device thus determines the momentaneous capabilities of the inverter 28. If the newly determined capabilities differ (significantly) from the earlier sent capabilities, then these newly determined capabilities are sent to the compensation control device 22.

[0254] The information flow is supposed to be asynchronous, in the sense that information is sent when there is something new to tell. Otherwise, the compensation handling device 26 stays silent to save communication bandwidth.

[0255] However, has time elapsed since the last time the compensation handling device 26 sent any information to the compensation control device 22, for instance longer than a defined time out interval, then a heartbeat is sent to indicate the compensation handling device 26 is still operational, and nothing new to report.

[0256] There is a delay in the loop, X374, to not measure unnecessary often and to impose some communication bandwidth consumption limitation. A return to the beginning of the loop is made, X376, when the delay has reached a delay threshold. The loop allows for asynchronous communication, that imply "Speak when you have something to tell”.

[0257] It can thus be seen that, the roles that the inverter 28 is capable of occupying may vary over time and that in this case the informing of the compensation control device about the roles that the inverter is capable of occupying may be performed regularly and this information may be received regularly, The instruction to act in at least one of the roles may in this case be an instruction to act in at least one role that the inverter is presently capable of performing.

[0258] A fourth loop is concerned with the sending of new role information from the compensation control device 22 to the compensation handling device 26 when a change of previous roles is needed. This is thus a loop that feeds commands to the compensation handling device 26 asking for role(s) to be changed.

[0259] The compensation control device 22 is constantly re-acting on conditions changed within the power grid.

[0260] The role determining element 57 of the compensation control device 22 determines one or more role that one or more of the inverters of the enhanced distribution networks are to occupy, X378, which determining may be based on a monitoring of an internal model of the power grid being operated by the stability investigating element 56 of the compensation control device 22.

[0261] The stability investigating element 56 of the compensation control device 22 is thus monitoring its internal model of the power grid, where input data of the model comprises the phase difference between voltage and current as seen at each power meter, the voltage timing as seen at each inverter, the power consumed as seen at each power meter, the power delivered as reported from each compensation handling device, the power being held back as reported from each compensation handling device and the load that is possible to apply as reported by each compensation handling device (battery charger).

[0262] Based on the application of this data in the model, the role determining element 57 of the compensation control device 22 then makes decisions on how to act to apply or maintain a certain type of activity in different areas of the region 19. If change of roles is needed, the role determining element 57 of the compensation control device 22 sends new roles to the compensation handling devices. The role determining element 57 of the compensation control device 22 thus investigates if the roles have changed for any of the enhanced power distribution networks, X380, and if the roles have changed with regard to an enhanced power distribution network, such as the first enhanced power distribution network 10, then the corresponding compensation handling device 26 is informed of the new roles in a message with role information (Rl ), X382, to which the compensation handling device 26 may respond with an ACK, X384.

[0263] Then a return to the beginning of the loop is made, X386, when a corresponding delay has reached a time out.

[0264] A fifth loop is concerned with investigating the conditions of the power grid.

[0265] The stability investigating element 56 of the compensation control device 22 is polling the power meters to get newly made measurement of voltage, current and phase difference between voltage and current.

[0266] With respect of the power meter 24 provided for the first enhanced power distribution network 10, the compensation control device 22 polls, X388, the power meter 24, which may involve requesting REQ, a list of power meter data PMD from the power meter 24, X388A, which data comprises Voltage, Current and the phase between voltage and current. The power meter 24 may then respond, X388B, with an ACK comprising the list with power meter data PMD. Then a return to the beginning of the loop is made, X390, when a corresponding delay has reached a time out.

[0267] The compensation control device 22 also operates in a sixth loop with the aim to react stabilizing through obtaining measurements of the power grid and sending stabilizing commands to compensation handling devices.

[0268] In this loop the compensation control device 22 obtains a list of power meter data PMD from the power meter 24, which data comprises voltage, Current and the phase between voltage and current from the power meter 24, X392A. It also obtains measurements and role capabilities MARC from the compensation handling devices, X392B. These obtainings may be made through fetching or receiving. The stability investigation element 56 may then investigate the stability of the power grid and the role determining element 57 may determine the activities to be performed by the enhanced power distribution networks, X394. Then the instruction sending element 62 of the compensation control device 22 sends instructions RAI to the compensation handling devices to act according to the previously determined roles, i.e. role acting instructions (RAI), X396. The compensation handling devices then in turn instructs the controllers of the corresponding enhanced power distribution network to control the inverter 28, X397, where the control of the inverter involves applying the role with a timing that is based on the time TO of the central clock adjusted with the modified time offset T1 '.

[0269] As an example the instruction can include one or more of the instructions described below:

[0270] Mimic Capacitor, amplitude 8 A, start at (TO + TT), ramp-up during 5 seconds, continue forever. Mimic Coil, amplitude 12 A, start at (TO + TT), ramp-up during 0 seconds, continue forever. Mimic power source, 12kW, start at (TO + TT), ramp-up during 30 seconds, continue forever. Mimic power load, 6kW, start at (TO + T1), ramp-up during 600 milli seconds, continue for 20 sec then ramp down during 2 seconds.

[0271] Mimic Capacitor, amplitude 6 A, run power source quadrants (as you are a power source), start immediately, continue forever.

[0272] Mimic Capacitor, amplitude 6 A, run power load quadrants (as you are a power load), start immediately, continue forever.

[0273] Mimic power source, 10kW, start at (TO + T1), ramp-up during 600 milli seconds, continue forever.

[0274] After reaching a time out, a return is made to the beginning of the loop, X398.

[0275] Measured values thus come into the compensation control device 22. The compensation control device 22 may then put the measurements into a model of the complete power grid. Decisions are then momentaneously taken on how to stabilize the region. The compensation control device 22 then sends role(s) to the compensation handling device(s) to counteract any instability as indicated by the measurements.

[0276] The compensation control device 22 thus investigates the stability of the grid including in the region 19 comprising the first and second enhanced power distribution networks 10, 12 and then instructs the compensation handling devices to act according to one or more role that assists in stabilising the grid. One way in which this can be done will now be described with reference being made to fig. 14 and 15, where fig. 14 schematically shows a number of method steps performed by the compensation control device 22 for making the inverters of the enhanced power distribution networks reduce a reactive load of the regions and fig. 15 schematically shows a number of method steps performed by the compensation control device 22 for making the inverters of the enhanced power distribution networks balance the load of the region 19.

[0277] In this case the investigation of the stability made by the stability investigating element 56 of the compensation control device 22 comprises investigating if the region 19 acts as a reactive load and the sending of an instruction to make an inverter 28 act according to at least one role comprises sending an instruction that causes a reduction of the reactive load.

[0278] The investigation of the stability may involve investigating the voltage of the region, the currents of the region and the phase angle between the currents and the voltage. This may be based on current and voltage measurements received from power meters and / or enhanced power distribution networks in the region 19 and the determining of the phase between the sum of currents of the region 19 and the voltage.

[0279] From this data it is possible to determine the amplitude of the current, the direction of the energy flow (in or out of the region) as well as if the provided power is active and / or reactive. In the case of reactive power it is also possible to determine if the reactive power is of the inductive or capacitive type.

[0280] The compensation control device 22 may investigate if the region 19 acts as a reactive load when investigating the stability of the power grid.

[0281] One determination that can be made by the stability investigating element 56 is thus to determine that the region acts as a reactive load, S500, which it does if the current is ahead of or behind the voltage, where a reactive load with current ahead of the voltage is a capacitive load and a reactive load with current behind the voltage is an inductive load.

[0282] The instruction sending element 62 then sends instructions to the compensation handling devices associated with the enhanced power distribution networks to make the corresponding inverter reduce the reactive load of the area, S502. It thus sends instructions that cause a reduction of the reactive load.

[0283] This may be done through letting the inverters of the enhanced power distribution network emulate a load that is of the opposite type compared with the region 19. The sent instructions may comprise instructions to mimic coils in case the load of the region is capacitive and to mimic capacitors in case the load of the region is inductive. More particularly, the instructing may involve instructing the compensation handling devices to order the inverters to mimic coils in all four quadrants of the current if they have this capability when the reactive load of the region is a capacitive load and to order the inverter to mimic a capacitor in all four quadrants of the current if they have this capability when the reactive load of the region is an inductive load.

[0284] The compensation may additionally be made locally for each enhanced power distribution network. For instance, if the load of the first enhanced power distribution network 10 is capacitive, the inverter 28 may be controlled to mimic a coil in all for quadrants in order to compensate this capacitive load, while if the load is inductive the inverter may be controlled to mimic a capacitor in all four quadrants in order to compensate the inductive load.

[0285] In these cases the timing of the mimicking is made in relation to the time TO of the central clock that has been adjusted with the modified first time offset T 1 ', i.e. ninety degrees after or ahead of the central clock TO adjusted with the modified first time offset TT depending on if a coil or a capacitor is mimicked.

[0286] This type of compensation cleans-out phase differences between voltage and current and thus compensates the reactive components on the power line to the region, which allows more power to be transmitted. This first type of compensation is here also denoted a first trick.

[0287] Put differently, each power meter may be monitored with the goal to see voltage and current in phase with each other. For that to happen, there is striving to balance-out currents to coil loads against currents to capacitor loads.

[0288] The compensation control device may regulate on amplitude of current vectors ninety degrees ahead or ninety degrees after the voltage vector. Timing wise those vectors may point at:

[0289] (TO + TT + (20ms / 4)) or (TO + TT - (20ms / 4) for a period of 20 ms. This balancing shall be done as local as possible, i.e. in the enhanced power distribution networks.

[0290] As was mentioned above, it is possible for an inverter to mimic a coil and to mimic a capacitor in order to compensate for reactive components. The voltage across a coil is a sine wave and the current through the coil is another sine wave that lags the voltage ninety degrees. This means that in a first quadrant the current is negative while the voltage is positive, in a second quadrant both the current and voltage are positive, in a third quadrant the current is positive while the voltage is negative, while in a fourth quadrant both the current and voltage are negative. When the product of current and voltage is positive energy goes into the coil, while when the product is negative energy goes out of the coil.

[0291] The capacitor has the same type of behaviour, but with a shift of one hundred and eighty degrees.

[0292] An inverter that mimics a coil or a capacitor thus supplies energy in two quadrants and receives energy in two other quadrants.

[0293] Furthermore, in order to be able to supply energy an enhanced power distribution network may need to have energy supply capacity, which may for instance be the case if it has a photovoltaic system. In a similar manner, in order to be able to receive energy the enhanced power distribution network will need to have energy storage capacity, which may for instance be the case when it has an energy storage system.

[0294] It is possible that one enhanced power distribution network does not have the required energy supply or energy storage capacity to be able to mimic a coil or capacitor that supplies energy. However, it is possible that another enhanced energy storage system does have such a capacity. In this case they may share the mimicking of the coil or capacitor. It is for instance possible that the first enhanced power distribution network 10 is unable to act as a load because the energy storage system 32 is fully loaded. However, it is possible that the second enhanced power distribution network 12 has this capability.

[0295] It is then possible that the compensation control device sends an instruction to the compensation handling device 26 associated with the first enhanced power distribution network 10 to order the associated inverter 28 to mimic a coil or a capacitor in the two energy supplying quadrants when the product of current and voltage is negative and sends an instruction to the compensation handling device associated with the second enhanced power distribution network 12 to order the associated inverter to mimic a coil or a capacitor in the two energy drawing quadrants when the product of current and voltage is positive. In this way it is possible for the two inverters to cooperate in the mimicking of a coil or capacitor.

[0296] If for instance the inverter 28 of the first enhanced power distribution network 10 has the photovoltaic system 30 as its back end it may act as a power source and if the inverter of the second enhanced power distribution network 12 has an energy storage system battery to charge as its back end. So it may act as a power load.

[0297] To mimic a capacitor, the two inverters need to become power source versus power load as time ticks away. The inverter 28 of the first enhanced power distribution network 10 may then run during the quadrants where a power source is needed to mimic a capacitor, while the inverter of the second enhanced power distribution network 12 may run during quadrants where a power load is needed to mimic a capacitor. The opposite operation is of course also possible. The sending of an instruction to mimic a coil or a capacitor may comprise sending an instruction to the compensation handling device 26 associated with the first enhanced power distribution network 10 to mimic a coil or a capacitor in two energy supplying quadrants and the sending an instruction to the compensation handling device associated with the second enhanced power distribution network 12 to mimic a coil or a capacitor in two energy drawing quadrants.

[0298] Another possible compensation is to compensate for an active load or active source in the region. This type of compensation may be combined with the reactive power compensation described above. This type of compensation, which is denoted a second trick, may be necessary if the region is to change between acting as a load and a source. Therefore, the stability investigating element 56 may, when investigating the stability of the power grid in the region, investigate if the region 19 acts as an active load or an active source, S600, which may again be done through investigating the current and voltage or current and phase angle, where the region is an active load if the current is in-phase with the voltage and an active source if the current is separated one-hundred and eighty degrees from the voltage. In this case the instruction sending element 62 sends an instruction that causes mitigation of the active load or source.

[0299] For instance, if the region acts as a load, S602, the instruction may be an instruction to act as a source, S604, while if the region acts as a source, S602, then the instruction may be the instruction to act as a load, S606. For instance, in case the region 19 acts as an active load, the compensation handling device 26 may be instructed to order the inverter 28 to act as an active power source where current is supplied one-hundred and eighty degrees from the adjusted timing. On the other hand, if the region 19 acts as an active power source, then the compensation handling device 26 may be instructed to order the inverter 28 to act as an active power load which supplies current in-phase with the adjusted timing.

[0300] This type of operations allows the balancing out of all power loads and power sources against each other in the region. Thereby the region becomes completely balanced and consumes no power and neither draws any power. This may be done in order to allow the region to be changed from operating as a load to operating as a source or vice versa.

[0301] The performing of the second trick may require that the first trick is finished and maintained.

[0302] The purpose of the second trick is to balance-out all power load and power source against each- other, so that a whole power distribution line branch become completely balanced and consume no power and take no current.

[0303] Monitored at each Power Meter, the purpose may be to see the current go to zero.

[0304] Here compensation control device is regulating on amplitude of current vectors in phase with voltage vector. Timing wise those vectors will point at

[0305] (TO + TT + O ms).

[0306] This balancing shall be done as local as possible. But can be done over larger areas as well. The goal is to reach zero current draw in longer power distribution lines.

[0307] As can be seen above it is possible for the region to go between acting as a load to acting as a source. When the region changes from acting as a load to acting as a source, the used timing may need to be changed in relation to the connection point 17. If an enhanced power distribution network in the region 19, such as the first enhanced power distribution network 10, has an individual first delay DE1 in relation to the timing of the first power source 14, the connection point 17 may have a second delay DE2 from the timing of the first power source 14, where additionally the first delay DE1 is longer then the second delay D2. Thus, the first enhanced power distribution network 10 has a timing that is delayed from the timing of the first power source 14 with the first delay DE1 and the connection point 17 has a timing that is delayed from the timing of the first power source 14 with a second delay DE2. If the region changes from acting as a load to acting as a source, it may be necessary to further adjust the timing used in the region. This further adjusting of the timing is here denoted a third trick.

[0308] How, this may be carried out will now be described with reference being made to Fig. 16 and 17, where fig. 16 schematically shows a number of method steps performed by the compensation control device 22 for determining a first difference to be used in a timing adjustment of the first enhanced power distribution network, and fig. 17 schematically shows a number of method steps performed by the compensation handling device 26 associated with the first enhanced power distribution network 10 for adjusting the timing of operations of the inverter 28 using the first difference.

[0309] In this case the stability investigating element 56 of the compensation control device 22 determines that the region 19 is to change from operating as a load to operating as a source, S700. The role determining element 57 may additionally determine the roles that the inverters of the enhanced power distribution networks that are to achieve this change are to occupy, S702, and the instruction sending element 62 may then send instructions to act according to these roles to the compensation handling devices, S704. Furthermore, the difference determining element 60 may also determine a first individual difference D1 for each enhanced power distribution network, which first difference is determined as the difference between the individual first delay DE1 of the corresponding enhanced power distribution network to the first power source 14 and the second delay DE2, which delays are both delays from the timing used at the first power source 14.

[0310] Thereafter the instruction sending element 62 orders the compensation handling devices associated with the enhanced power distribution networks in the region to adjust the timing used in the at least one instructed role based on the first difference D1, S708, which first difference D1 is the difference between the corresponding first delay and the second delay. It may optionally also send the individual first differences D1 to the compensation handling devices, S710. It may thus inform the compensation handling devices about the first differences D1.

[0311] The different compensation handling devices then receive the instructions to act according to the roles and also the individual timing adjustment orders. If the first difference is sent by the compensation control device, they also receive the individual first difference D1. Thereafter the compensation handling devices order the corresponding inverter to perform the role with a timing that has been adjusted based on the corresponding first difference D 1. The adjusted offset may for instance be further adjusted based on the first difference. It is more particular possible that the adjusted first offset T1' is reduced based on the first difference D1.

[0312] The further timing adjusting may be an adjusting with twice the first difference D1, or two times the first difference, i.e. with 2*D1.

[0313] The ordering of the inverter to perform the role with an adjusted timing may thus be an order to perform the role with a timing that in addition to the ordered timing is adjusted with twice the first difference D1. When the compensation control device sends individual timing adjustment orders, each such order may alternatively comprise the actual further timing adjustment, i.e. twice the first difference D1. Alternatively, when only receiving the first difference D1, each compensation handling device may determine the timing adjustment based on the received first difference D1, i.e. determine the timing adjustment as twice the first difference D1 .

[0314] When applied in the compensation handling device 26 associated with the first enhanced power distribution network 10, this device 26 thus receives the instruction to act according to at least one role, S800, and also the individual timing adjustment order, S802. It may here also receive information about the individual first difference D1 or the actual adjustment, S804. The timing adjusting element 44 then adjusts the timing that the inverter 28 is to use based on the first difference D1, here with 2*D1 . Thereafter the role handling element 46 of the compensation handling device 26 orders (via the controller 33) the inverter 28 to perform the role with the timing that has been adjusted based on the corresponding first difference D1, S806. The adjusted first time offset TT may for instance be further adjusted with twice the first difference D1, where the adjusted first time offset TT may be reduced with twice the first difference D1 . The compensation handling device 26 thus further adjusts the timing used in the at least one instructed role based on the first difference D1 if the region 19 is to change from operating as a load to operating as a source, where the first difference D1 is the difference between the first delay DE1 and the second delay DE2. Put differently, the at least one role is performed with a timing that has been further adjusted based on the first difference D 1 , where the actual adjustment may be the adjustment with twice the first difference D1 . Alternatively, it is possible that the different compensation handling devices determine and use the individual first differences themselves.

[0315] Furthermore, it is likewise possible that the compensation control device 22 determines that the region is to stop operating as a source and return to operating as a load. It is in this case possible that the balancing out of power load and powers sources against each other is again performed and that the reactive power compensation is thereafter performed using the adjusted first time offset without the adjustment that is based on the first difference.

[0316] The performing of the third trick may require that the first and second tricks are finished and maintained.

[0317] The purpose of the third trick is to switch the region from power consuming timing to power production timing and then increase power production in the region, so that it becomes a power source. However, it should not deliver more power than needed for having power sources held back to ensure local self-contained stability in the region. This is "stability headroom”.

[0318] It should be possible to run all power sources at full power, while providing "stability headroom” by regulating at quickly controlled loads instead of holding power sources back.

[0319] The performing of the third trick may additionally be described in the following way:

[0320] Through the performing of the first and second tricks at the different enhanced power distribution networks, reactive loads and resistive loads have been balanced out in as many local points as possible.

[0321] In order to understand the third trick, propagation delay needs to be studied.

[0322] In the power grid shown in fig. 1, the first power line 16 starts at the first power source 14 and passes by the connection point 17 that as an example can be placed on a distance that is 900 km from the first power source 14. The region 19 with the first enhanced power distribution network 10 can as an example be located 300 km from the connection point 17. Now imagine that a voltage positive zero crossing at phase R, starting at the first power source 14 is travelling along the first power line 16 towards the region 19 with the speed of light. Timing at the first power source 14 can typically be said to be T1 =0 ms.

[0323] After 900km, 3ms later, it passes the connection point 17, and continues into the region 19 towards the first enhanced power distribution network 10. Timing at the connection point 17 can typically be said to be T1=-3ms. (the positive zero crossing is seen 3ms later.)

[0324] After 900km + 300km, 3ms + 1ms later, it reaches the first enhanced power distribution network 10, which may be seen as the outermost point of the region 19. Timing at the first enhanced power distribution network 10 when this acts as a load can typically be said to be T1 = -(3ms + 1ms) = - 4ms. (the positive zero crossing is seen 4ms later.) T 1 = -4ms is the timing when the energy flow is from the first power source 14 to the connection point 17 and the first enhanced power distribution network 10, meaning there are mostly energy consumption going on along the first and second power lines 16, 18. The connection point 17 is in this case a power passage point in that power from the first power source 14 passes the connection point 17 as it is transmitted to the region 19. The region 19 with the first enhanced power distribution network 10 is thus located after the connection point 17 in the flow of power from the first power source 14.

[0325] However, should it be desirable to make the connection point 17 into a merge point instead, where a positive zero crossing from the first enhanced power distribution network 10 acting as a source shall line-up with a positive zero crossing at the connection point 17, then the timing at the first enhanced power distribution network 10 needs to change.

[0326] To time correctly in the merge point 17, timing at the first enhanced power distribution network 10 can typically be said to be T1 = -4ms + 1ms + 1ms = -2ms.

[0327] When the positive zero crossing from the first power source 14, running along the first power line 16, passes the merge point 17, then the corresponding positive zero crossing from the first enhanced power distribution network 10 acting as a source must have started earlier to time correctly at the merge point 17.

[0328] Thus, at the first enhanced power distribution network 10 acting as a load, T 1 = -4ms. (Power load mode.) Thus, at the first enhanced power distribution network acting as a source, T1 = -2ms. (Power source mode.)

[0329] So, it is necessary to provide orchestration of timing for the inverters involved to correctly go from mostly energy consumption to mostly energy production. In "power source mode” it is necessary to consider the wave going from the connection point 17 towards the first enhanced power distribution network 10, the outgoing wave as well as the wave going from the first enhanced power distribution network 10 towards the connection point 17, the ingoing wave. The inverters need to be controlled in such a way that the outgoing wave is attenuated in favour of the ingoing wave.

[0330] The transition between "power load mode” to "power source mode” can be described in the following way.

[0331] If starting in "power load mode”, the first enhanced power distribution network 10 may be mostly power consumers, in which case the first enhanced power distribution network 10 may have less energy available internally than is being consumed. Through the compensation control device performing the first and second tricks the available energy may then increase and it is possible to reach a fully balanced state where the first enhanced power distribution network 10 consumes as much energy as it produces.

[0332] It is possible to stay at this balance point, where no energy is taken from the connection point 17 until there is some headroom with more energy available than is consumed.

[0333] Then the compensation control device may decide that there is enough energy available to transition from "power load mode” to "power source mode”.

[0334] The compensation control device 22 may ask the involved inverters (via the corresponding compensation handling devices) to go, slowly and together, from TT = -4ms to TT - (2*D1) = -2ms. (Note, TT values mentioned are for the first enhanced power distribution network 10. Time offset values differ along the distance between the connection point 17 and the first enhanced power distribution network 10.)

[0335] For this reason, the compensation control device 22 may send timing slide commands for controlling a gradual change of timing from the timing using the modified first time offset to the timing using the modified first time offset T decreased with twice the first difference D1 .

[0336] A timing slide command may then have the following look: Slide forward in time (put later) (increase adjustment x), [start at TO+x, where x = (T1'-2*D1) =”a future point in time”, slide speed, slide until x=T1'].

[0337] Slide backward in time (put earlier) (decrease adjustment x), [start at TO+x, where x=T T =”a future point in time”, slide speed, slide until x=T1'-2*D1],

[0338] When at "power source timing”, T1 = -2ms, then the second trick may be repeated. This time the energy put onto the power grid over time is increased to reach a new balance point where the first enhanced power distribution network is a power source and deliver power onto merge point 17. It is possible to leave some headroom, so that it is possible to stay in this new balance point as energy available and energy consumed vary over time.

[0339] Here it is possible to continuously run the first and second tricks to stay in balance. The orchestration of transition from "power load mode” to "power source mode” described above is the third trick.

[0340] Which trick to do over time, in each point-of-network / section-of-network / along-a-powerline, is determined by the compensation control device.

[0341] Power meters measure current (ampere) and phase difference between voltage and current.

[0342] Compensation handling devices control the inverters to measure voltage timing. They also tell the compensation control device what role(s) the inverters can do. However, neither power meters nor compensation handling devices know which Trick is ongoing. That is "known” by the compensation control device 22. While maintaining the second trick or the third trick, it should be possible to rely on local "stability headroom”. Thus, providing the opportunity to run the first power line at full power, rather than holding this powerline back to provide "stability headroom” for the region.

[0343] When the third trick is no longer possible, as power sources and power loads balancing is about to permanently consume the local "stability headroom”, then it is time to revert to power consume timing and drop the third trick. Likewise, the second trick may need to be dropped if the power sources and power loads balancing can no longer be maintained. However, it may still be possible to provide local "stability headroom” while aiming for the second trick, if there are power sources and / or power loads that can be quickly regulated.

[0344] The change from power load mode to power source mode may additionally be described in the following way: When leaving "power load mode”, the compensation control device 22 may instruct the compensation handling device 26:

[0345] Your new timing, start at (TO + T1' (current TT that is)), smoothly traverse to TT-2*D1 over 30 s.

[0346] Note: The compensation control device 22 knows the "closest power meter ID” for this compensation handling device 26 and can then look-up connection point "CP”, mentioned earlier, to get second delay DE2 of connection point CP. Based on the known first delay DE1, the first difference D1 was then calculated.

[0347] The compensation control device 22 may then communicate with the compensation handling device 26 for ramping up power in the "power source mode”:

[0348] Mimic power source, 22kW, start at (TO + (TT-2*D1)), ramp-up during 120 s, continue forever.

[0349] In order to ramp down power in preparation for leaving the "power source mode”, the compensation control device 22 may then instruct the compensation handling device 26:

[0350] Mimic power source, 10kW, start at (TO + (TT-2*D1)), ramp-down during 2 seconds, continue forever.

[0351] In order to leave the "power source mode” and enter "power load mode”, the compensation control device 22 may then instruct the compensation handling device 26:

[0352] Your new timing, start at (TO + (TT-2*D1) (current T1 that is)), smoothly traverse to TT over 30 s.

[0353] The timing may be carried using timer logic with skew filters in the controller of the inverter. How this can be used will now be briefly discussed.

[0354] In the region three phases are used, R S T. However, only one of them is used for determining the timing. In this example the timing of the R phase is determined. The timing of the other two can be determined from the timing of R. Within phase R, there are many points in time that are needed to be known for the taking on different roles, like timing of a capacitor, timing of a coil, timing of a resistor. However, it is possible to calculate all those points in time locally from the positive zero transition of a phase, such as the phase R voltage. Likewise, all timing within phase S can be locally calculated from positive zero transition of phase R voltage as can all timing within phase T.

[0355] The wall clock, the TO counter / timer, is constantly counting up an integer value that represent current time. TO may be set fairly infrequently, maybe once a day.

[0356] All inverters may have a local TO and all TO keep the same time.

[0357] When determining the first time offset, a first detector may be watching TO. Each 20ms the detector activates a signal that say it is time for a positive zero crossing at phase R. A second detector may be watching TO counter / timer via a skew filter.

[0358] Initially the first time offset T 1 may be set to zero. The skew filter takes the parameter T1 . It adds the T 1 value to TO so that the second detector sees TO + T1 at each moment in time. Because of this the first and second detectors detect events at the same time. This is due to the fact that T 1 = 0 ms and do not affect the TO value as seen by the second detector.

[0359] (TO + T1 = TO + 0 ms).

[0360] As more negative values of T 1 are placed in the skew filter, the events announced by the detector are delayed in time.

[0361] At (T1 = -10ms) the positive zero crossing, has moved to where the next negative zero crossing used to be. At (T1 = -20ms) the positive zero crossing, has moved to where the next positive zero crossing used to be. At (T1 = -40ms) the positive zero crossing, has moved to two full wavelengths later.

[0362] Likewise, it is possible to move forward in time to get back to the original timing at (T1 = 0ms). At (T 1 = 10ms) the positive zero crossing, has moved to half a wavelength earlier. At (T1 = 20ms) the positive zero crossing, has moved to one full wavelength earlier. Note that setting of a new T 1 value shall cause the skew filter to smoothly change to the new T 1 without skipping any counts on the way. This so that the detector will not miss any event during transition between T 1 values. This mechanism allows for use of unique T 1 values for each point in the power grid as well as smooth transition between T 1 values. Also, T 1 values can be updated to adapt for slow frequency drift of the power grid, even if the drift may accumulate to large number of full wavelengths.

[0363] The timers used for TO and T 1 (Timer 0 and Timer 1) may be realized as two 64-bit registers, while the skew filter may be realized as a a 64-bit adder..

[0364] Each compensation handling device, controller or inverter may have logic that can contain:

[0365] TO and T 1 registers, with logic to smoothly set new values that continuously drift from old value to new value over defined time without skipping any counter states.

[0366] Crystal oscillator with pre-scaler to step TO for correct wall clock time.

[0367] Adder or similar implementation of skew filter to apply T 1 offset to TO.

[0368] Detector to announce proper timing for all events needed, derived from (TO + T1).

[0369] The inverter role may be set per phase (R S T), but all timing may be derived from the crossing of one voltage reference level of one phase, such as the voltage positive zero transition of phase R.

[0370] All enhanced power distribution networks may have one "closest power meter” defined. This power meter is typically situated towards the power grid as seen from the inverter of the enhanced power distribution network.

[0371] A "hardware local logic” described above may be implemented as a highly integrated module of an inverter. This module may provide timing and role(s) to the inverter, and ask the inverter for currently available energy, possible role(s), voltage timing seen. The size of the inverter (its energy handling properties) is entirely properties of the inverter, while the same implementation of "hardware local logic” can be used for a large span of inverters.

[0372] In the compensation handling device:

[0373] ■ the time offset determining element may be considered to comprise means for obtaining a time of a central clock, means for obtaining a time of a crossing of a reference level of a phase at the first enhanced power distribution network, means for determining the first time offset and optionally also means for providing the first time offset to the compensation control device,

[0374] ■ the role capability investigating element, if present, may be considered to comprise means for informing the compensation control device of the roles the inverter is capable of occupying,

[0375] ■ the timing adjusting element, if present, may be considered to comprise means for receiving a modified first time offset from the compensation control device, means for adjusting the timing of the inverter with the modified first time offset and optionally also means for receiving information about the first difference from the compensation control device and means for adjusting the timing used in the at least one instructed role with the first difference,

[0376] ■ the role handling element may be considered to comprise means for receiving an instruction to act in at least one of the roles and means for ordering the inverter to act in the at least one instructed role.

[0377] The means for obtaining a time of a crossing of a reference level of a phase at the first enhanced power distribution network may be considered to comprise means for collecting voltage measurements and means for determining the time of the crossing of the reference level of the phase based on the voltage measurements.

[0378] The means for informing the compensation control device of the roles the inverter is capable of occupying may comprise means for regularly informing the compensation control device about the roles that the inverter is capable of occupying.

[0379] In the compensation control device:

[0380] ■ the central clock providing element, if present, may be considered to comprise means for providing the compensation handling devices with the time of the central clock,

[0381] ■ the stability investigating element may be considered to comprise means for investigating the stability of the power grid and optionally also as means for determining that the region is to change from operating as a load to operating as a source,

[0382] ■ the role determining element, if present, may be considered to comprise means for receiving information from the compensation handling devices of the roles the corresponding inverters are capable of occupying and means for determining at least one role that the corresponding inverters are to occupy, ■ the offset determining element, if present, may be considered to comprise means for obtaining the individual first time offsets from each of the compensation handling devices, means for determining an individual modified first time offset for each of the enhanced power distribution networks and means for providing each individual modified first time offset to the corresponding compensation handling devices,

[0383] ■ the delay determining element, if present, may be considered to comprise means for determining the first difference, and

[0384] ■ the instruction sending element may be considered to comprise means for sending an instruction to at least some of a number of compensation handling devices.

[0385] The means for investigating the stability of the power grid may comprise means for investigating if the region acts as a reactive load and the means for sending an instruction may comprise means for sending instructions that causes a reduction of the reactive load.

[0386] The means for sending an instruction may additionally comprise means for sending an instruction to mimic a coil in case the load of the region is capacitive and to mimic a capacitor in case the load of the region is inductive. The means for sending an instruction to mimic a coil or a capacitor may additionally comprise means for sending an instruction to a compensation handling device associated with a first enhanced power distribution network to mimic a coil or a capacitor in two energy supplying quadrants and means for sending an instruction to a compensation handling device associated with a second enhanced power distribution network to mimic a coil or a capacitor in two energy drawing quadrants.

[0387] The means for investigating the stability of the power grid may comprise means for investigating if the region acts as an active load or an active source and the means for sending an instruction may comprise means for sending an instruction that causes mitigation of the active load or active source. More particularly, the means for sending an instruction may comprise means for sending an instruction to act as an active power source.

[0388] The stability investigating element may further be considered to comprise means for determining that the region is to change from operating as a load to operating as a source and the instructing sending element may be further considered to comprise means for ordering the compensation handling devices associated with the enhanced power distribution networks in the region to adjust the timing used in the at least one instructed role based on the first difference. 6o

[0389] The means for receiving information from the compensation handling devices of the roles the corresponding inverters are capable of occupying may comprise means for regularly receiving this information and the means for determining at least one role that the corresponding inverters are to occupy, may be means for determining at least one role that the inverters are presently capable of performing.

[0390] While aspects of the present disclosure have been described in connection with what is presently considered to be most practical and preferred embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements. Therefore, the disclosure is only to be limited by the following claims.

Claims

CLAIMS1. A power compensating arrangement (25) comprising a compensation handling device (26) handling power compensation performed by a first enhanced power distribution network (10) adapted to be connected to a three-phase power grid (16, 18), the first enhanced power distribution network (10) comprising at least one inverter (28) capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role, the compensation handling device (26) comprising a processor (34) operative to: obtain (X100; X200; X310, X350) a time of a central clock (TO), obtain (X104; X204; X316, X360) a time of a crossing of a reference level of a phase at the first enhanced power distribution network (10), determine (X105; X206; X317; X361) a first time offset (T1) from the central clock as a difference in time between the time of the crossing of the reference level and the time of the central clock (TO), receive (X108; X222; X396), from a compensation control device (22), an instruction to act in at least one of the roles, and order (X110, X224, X397) the inverter (28) to act in the at least one instructed role with a timing that is based on the central clock adjusted with the first time offset.

2. The power compensating arrangement (25) according to claim 1, wherein the at least one active compensating role comprises an active power load role and an active power source role, where an unadjusted active power load role is provided through a phase current that is in-phase with a corresponding phase voltage, an unadjusted active power source role is provided through a phase current that is one hundred and eighty degrees displaced from the corresponding phase voltage, an unadjusted coil mimicking role is provided through a phase current that is ninety degrees after the corresponding phase voltage and an unadjusted capacitor mimicking role is provided through a phase current that is ninety degrees before the corresponding phase voltage.

3. The power compensating arrangement (25) according to claim 1 or 2, wherein the crossing of the reference level is a positive or negative zero-crossing of a phase.

4. The power compensating arrangement (25) according to any previous claim, wherein the compensation handling device (26) is further operative to provide (X208; X318) the first time offset (T1) to the compensation control device (22) and receive (X212; X322) a modified first time offset(TT) from the compensation control device (22), wherein the timing used by the inverter (28) is based on the central clock (TO) adjusted with the modified first time offset (TT).

5. The power compensating arrangement (25) according to any previous claim, wherein the phase is the phase of a voltage and the compensation handling device (26) is further operative to collect (X102; X202; X358) voltage measurements and determine (X105; X206; X361) the time of the crossing of the reference level of the phase based on the voltage measurements.

6. The power compensating arrangement (25) according to any previous claim, further comprising a power meter (24) associated with the first enhanced power distribution network (10).

7. The power compensating arrangement (25) according to any previous claim, further comprising the inverter (28) and any power generating system (30) or energy storage system (32) of the first enhanced power distribution network (10).

8. The power compensating arrangement (25) according to any previous claim, wherein the coil mimicking roles comprise a first coil mimicking role in which a coil is mimicked in four quadrants, a second coil mimicking role in which a coil is mimicked in two energy supplying quadrants and a third coil mimicking role in which a coil is mimicked in two energy drawing quadrants, and the capacitor mimicking roles comprise a first capacitor mimicking role in which a capacitor is mimicked in four quadrants, a second capacitor mimicking role in which a capacitor is mimicked in two energy supplying quadrants and a third capacitor mimicking role in which a capacitor is mimicked in two energy drawing quadrants9. The power compensating arrangement (25) according to any previous claim, wherein the first enhanced power distribution network (10) is provided in a region (19) of the power grid (16, 18), which region (19) is connected to a first power source (14) via a connection point (17), the first enhanced power distribution network (10) has a timing that is delayed from the first power source (14) with a first delay (DE1) and the connection point (17) has a timing that is delayed from the timing of the first power source (14) with a second delay (DE2) , and the compensation handling device (26) being further operative to adjust the timing used in the at least one instructed role with a first difference (D 1 ) in case the region is to change from operating as a load to operating as a source, which first difference (D 1) is based on the difference between the first delay (DE1) and the second delay (DE2).

10. The power compensating arrangement (25) according to claim 9, the compensation handling device (26) being further operative to receive information about the first difference (D1) or the timing adjustment from the compensation control device (22).11 . The power compensating arrangement (25) according to any previous claim, the compensation handling device being further operative to inform (X218; X330, X372) the compensation control device (22) of the roles the inverter (28) is capable of occupying.

12. The power compensating arrangement (25) according to claim 11, wherein the roles that the inverter (28) is capable of occupying vary over time, the informing (X372) the compensation control device (22) about the roles that the inverter (28) is capable of occupying is performed regularly and the instruction to act in at least one of the roles is an instruction to act in at least one role that the inverter (28) is presently capable of performing.

13. The power compensating arrangement (25) according to any previous claim, wherein the compensation handling device is combined with a controller (33) controlling the operation of the inverter.

14. The power compensating arrangement (25) according to any previous claim, wherein the compensation handling device (26) is a user equipment associated with one or more mobile communication networks (20).

15. A method of handling power compensation performed by a first enhanced power distribution network (10) adapted to be connected to a three-phase power grid (16, 18), the first enhanced power distribution network (10) comprising at least one inverter (28) capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role, the method being performed in a compensation handling device (26) and comprising: obtaining (S100; X100, S300, X200; X310, X350) a time (TO) of a central clock, obtaining (S102, X104; S304, X204; X316, X360); a time of a crossing of a reference level of a phase at the first enhanced power distribution network (10), determining (S104, X105; S306, X206; X317; X361) a first time offset (T1) from the central clock as a difference in time between the time of the crossing of the reference level and the time of the central clock,receiving (S106, X108; S318, X222; X396; S800), from the compensation control device (22), an instruction to act in at least one of the roles, and ordering (S108, X110, S320, X224; S320, X397; S806) the inverter to act in the at least one instructed role with a timing that is based on the central clock (TO) adjusted with the first time offset (T1).

16. The method according to claim 15, further comprising providing (S308, X208; X318) the first time offset (T1) to the compensation control device (22) and receiving (S310, X212; X322)a modified first time offset (TT) from the compensation control device (22), wherein the timing used by the inverter (28) is based on the central clock (TO) adjusted with the modified first time offset (TT).

17. The method according to claim 15 or 16, wherein the phase is the phase of a voltage and further comprising collecting (X102; S302, X202; X358) voltage measurements and determining (X105, S304, X206; X361) the time of the crossing of the reference level of the phase based on the voltage measurements.

18. The method according to any of claims 15 - 17, wherein the coil mimicking roles comprise a first coil mimicking role, in which a coil is mimicked in four quadrants, a second coil mimicking role in which a coil is mimicked in two energy supplying quadrants and third coil mimicking role in which a coil is mimicked in two energy drawing quadrants and the capacitor mimicking roles comprise a first capacitor mimicking role, in which a capacitor is mimicked in four quadrants, a second capacitor mimicking role in which a capacitor is mimicked in two energy supplying quadrants and third capacitor mimicking role in which a capacitor is mimicked in two energy drawing quadrants.

19. The method according to any of claims 15 - 18, wherein the first enhanced power distribution network (10) is provided in a region (19) of the power grid (16, 18), which region (19) is connected to a first power source (14) via a connection point (17), the first enhanced power distribution network (10) has a timing that is delayed from the power source with a first delay (DE1) and the connection point (17) has a timing that is delayed from the timing of the first power source (14) with a second delay (DE2), the method further comprising performing (S8o6) the at least one role with a timing that has been adjusted based on a first difference (D 1 ) in case the region is to change from operating as a load to operating as a source, which first difference (D 1 ) is the difference between the first delay (DE1) and the second delay (DE2).

20. The method according to claim 19, further comprising receiving (S804) information about the first difference (D1) or the timing adjustment from the compensation control device.

21. The method according to any of claims 15 - 20, further comprising informing (S316; X218; X330, X372) the compensation control device (22) of the roles the inverter (28) is capable of occupying.

22. The method according to claim 21, wherein the roles that the inverter is capable of occupying vary over time, the informing the compensation control device (22) about the roles that the inverter (28) is capable of occupying is performed regularly and the instruction to act in at least one of the roles is an instruction to act in at least one role that the inverter (28) is presently capable of performing.

23. A computer program for handling power compensation performed by a first enhanced power distribution network (10) adapted to be connected to a three-phase power grid (16, 18), the first enhanced power distribution network (10) comprising at least one inverter (28) capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role, the computer program comprising computer program code (38) which when run by a processor (34) of a compensation handling device (26) implements the method according to any of claims 15 - 22.

24. A computer-readable medium (36) for handling power compensation performed by a first enhanced power distribution network (10) adapted to be connected to a three-phase power grid (16, 18), the first enhanced power distribution network (10) comprising at least one inverter (28) capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role, the computer readable-medium (36) comprising computer program code (38) which when run by a processor (34) of a compensation handling device (26) implements the method according to any of claims 15 - 22.

25. A compensation control device (22) for performing power compensation in a three-phase power grid (16, 18) to which one or more enhanced power distribution networks (10, 12) are connected, each enhanced power distribution network (10, 12) being provided in a region (19) of the power grid (16, 18) and comprising at least one inverter (28) capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and atleast one capacitor mimicking role, the compensation control device (22) comprising a processor (48) operative to: investigate (X106; X220; X392, X394) the stability of the power grid (16, 18) in the region (19), and send (X108; X222; X396) an instruction to at least some of a number of compensation handling devices (26), each associated with a corresponding enhanced power distribution network (10), to make the inverter (28) of the corresponding enhanced power distribution network (10) act according to at least one of the roles for stabilising the power grid (16, 18) in the region (19), where the inverter (28), when acting in the at least one role applies a timing that is based on a central clock (TO) adjusted with an individual first time offset (T1), which individual first time offset (T1) is a difference in time between the time of a crossing of a reference level of a phase at the corresponding enhanced power distribution network and the time of the central clock(TO).

26. The compensation control device (22) according to claim 25, being further operative to provide (X200; X310; X350B) said number of compensation handling devices (26) with the time (TO) of the central clock.

27. The compensation control device (22) according to claim 25 or 26, being further operative to obtain (X208; X318, X364) the individual first time offsets (T1) from each of the compensation handling devices (26), determine (X210; X320) an individual modified first time offset (T ) for each of the enhanced power distribution networks (10, 12) and provide (X212; X322) each individual modified first time offset (TT) to the corresponding compensation handling devices (26).

28. The compensation control device (22) according to any of claims 25 - 27, wherein the compensation control device (22) is further operative to investigate if the region (19) acts as a reactive load when investigating the stability of the power grid and being further operative to send instructions that causes a reduction of the reactive load when sending an instruction to make an inverter (28) act according to at least one role.

29. The compensation control device (22) according to claim 28, wherein the instruction comprises an instruction to mimic a coil in case the load of the region (19) is capacitive and to mimic a capacitor in case the load of the region (19) is inductive.

30. The compensation control device (22) according to claim 29, wherein the coil mimicking roles comprise a first coil mimicking role, in which a coil is mimicked in four quadrants, a second coil mimicking role in which a coil is mimicked in two energy supplying quadrants and a third coilmimicking role in which a coil is mimicked in two energy drawing quadrants and the capacitor mimicking roles comprise a first capacitor mimicking role, in which a capacitor is mimicked in four quadrants, a second capacitor mimicking role in which a capacitor is mimicked in two energy supplying quadrants and a third capacitor mimicking role in which a capacitor is mimicked in two energy drawing quadrants and the sending of an instruction to mimic a coil or a capacitor comprise sending an instruct a compensation handling device (26) associated with a first enhanced power distribution network (10) to mimic a coil or a capacitor in two energy supplying quadrants and sending an instruction to a compensation handling device associated with a second enhanced power distribution network to mimic a coil or a capacitor in two energy drawing quadrants.31 . The compensation control device (22) according to any of claims 25 - 30, wherein the compensation control device (22) is further operative to investigate if the region (19) acts as an active load or an active source when investigating the stability and being further operative to send an instruction that causes mitigation of the active load or active source when sending an instruction to make an inverter (28) act according to at least one role.

32. The compensation control device (22) according to claim 31, wherein the active compensating roles comprise an active power load role and an active power source role and the instruction comprises an instruction to act as an active power source in case the region (19) acts as an active load and to act as an active power load in case the region (19) acts as an active power source.

33. The compensation control device (22) according to any of claims 25 - 32, wherein the region (19) is connected to a first power source (14) via a connection point (17), each enhanced power distribution network (10, 12) has a timing that is delayed from the first power source (14) with a corresponding first delay (DE1) and the connection point (17) has a timing that is delayed from the timing of the first power source (14) with a second delay (DE2), the compensation control device (22) being further operative to determine that the region is to change from operating as a load to operating as a source and order the compensation handling devices (26) associated with the enhanced power distribution networks (10, 12) in the region to adjust the timing used in the at least one instructed role based on a first difference (D 1 ), which first difference (D 1 ) is the difference between the corresponding first delay (DE1) and the second delay (DE2).

34. The compensation control device (22) according to claim 33, being further operative to determine the first difference (D1) and inform said compensation handling device (26) of it or the timing adjustment.

35. The compensation control device (22) according to claim 33 or 34, wherein the timing adjustment is two times the first difference (D1).

36. The compensation control device (22) according to any of claims 25 - 35, being further operative to receive (X218; X330, X372) information from the compensation handling devices (26) of the roles the corresponding inverters (28) are capable of occupying and where the instruction to act according to at least one role is an instruction to act in at least one role the inverter (28) is capable of occupying.

37. The compensation control device (22) according to claim 36, wherein the roles that the inverters (28) are capable of occupying vary over time, the information of these capabilities is received regularly (X372) and the instruction to act according to at least one role is an instruction to act in at least one role that the corresponding inverter (28) is presently capable of performing.

38. A method of controlling a power compensation in a region (19) of a three-phase power grid (16, 18) to which one or more enhanced power distribution networks (10, 12) are connected, each enhanced power distribution network (10, 12) being provided in a region (19) of the power grid (16, 18) and comprising at least one inverter (28) capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role, the method comprising: investigating (S200, X106; S410, X220; X392, X394) the stability of the power grid (16, 18) in the region (19), and sending (S202, X108; S414, X222; X396; S704) an instruction to at least some of a number of compensation handling devices (26), each associated with a corresponding enhanced power distribution network (10), to make the inverter (28) of the corresponding enhanced power distribution network (10) act according to at least one of the roles for stabilising the power grid (16, 18) in the region (19), where the inverter (28), when acting in the at least one role applies a timing that is based on a central clock (TO) adjusted with an individual first time offset (T1), which individual first time offset (T1) is a difference in time between the time of a crossing of a reference level of a phase at the corresponding enhanced power distribution network (10) and the time of the central clock (TO).

39. The method according to claim 38, further comprising providing (S400, X200; X310;X350B) said number of compensation handling devices (26) with the time of the central clock (TO).

40. The method according to claim 38 or 39, further comprising obtaining (S402, X208; X318, X364) the individual first time offsets (T1) from each of the compensation handling devices (26), determining (S404, X210; X320) an individual modified first time offset (T ) for each of the enhanced power distribution networks (10, 12) and providing (S406, X212; X322) each individual modified first time offset (TT) to the corresponding compensation handling devices (26).41 . The method according to any of claims 38 - 40, wherein the investigating the stability of the power grid in the region comprises investigating (S500) if the region (19) acts as a reactive load and the sending of an instruction to make an inverter act according to at least one role comprises sending (S502) an instruction that causes a reduction of the reactive load.

42. The method according to any of claims 38 - 41, wherein the investigating the stability of the power grid in the region comprises investigating (S600) if the region (19) acts as a load or a source and the sending of an instruction to make an inverter act according to at least one role comprises sending an instruction (S604, S606) that causes mitigation of the load or source.

43. The method according to any of claims 38 - 42, wherein the region (19) is connected to a first power source (14) via a connection point (17), each enhanced power distribution network (10, 12) has a timing that is delayed from the first power source (14) with a corresponding first delay (DE1) and the connection point (17) has a timing that is delayed from the timing of the first power source (14) with a second delay (DE2) , the method further comprising determining (S700) that the region is to change from operating as a load to operating as a source and ordering (S708) the compensation handling devices (26) associated with the enhanced power distribution networks (10, 12) of the region to adjust the timing used in the at least one instructed role based on a first difference (D1), which first difference (D1) is the difference between the corresponding first delay (DE1) and the second delay (DE2).

44. The method according to claim 43, further comprising determining (S706) the first difference and informing (S710) said compensation handling devices (26) about it or the timing adjustment.

45. The method according to any of claims 38 - 44, further comprising receiving (S408, X218; X330, X372) information from the compensation handling devices (26) of the roles the corresponding inverters (28) are capable of occupying and where the instruction to act according to at least one role is an instruction (S414) to act in at least one role the inverter (28) is capable of occupying.

46. A computer program for controlling a power compensation in a region (19) of a three- phase power grid (16, 18) to which one or more enhanced power distribution networks (10, 12) are connected, each enhanced power distribution network (10, 12) being provided in a region (19) of the power grid (16, 18) and comprising at least one inverter (28) capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role, the computer program comprising computer program code (52) which when run by a processor (48) of a compensation control device (22) implements the method according to any of claims 38 - 45.

47. A computer-readable medium (50) for controlling a power compensation in a region (19) of a three-phase power grid (16, 18) to which one or more enhanced power distribution networks (10, 12) are connected, each enhanced power distribution network (10, 12) being provided in a region (19) of the power grid (16, 18) and comprising at least one inverter (28) capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role, the computer readable-medium (50) comprising computer program code (52) which when run by a processor (48) of a compensation control device (22) implements the method according to any of claims 38 - 45.

48. A power compensation system comprising a compensation control device (22) for performing power compensation in a three-phase power grid (16, 18), one or more enhanced power distribution networks (10, 12) connected to the power grid (16, 18) and one or more compensation handling devices (26), each associated with a corresponding enhanced power distribution network (10), where each enhanced power distribution network (10, 12) is provided in a region (19) of the power grid (16, 18) and comprises at least one inverter (28) capable of operating in a number of roles comprising at least one active compensating role, at least one coil mimicking role and at least one capacitor mimicking role, the compensation control device (22) comprising a processor (48) operative to: investigate (X106; X220; X392, X394) the stability of the power grid (16, 18) in the region (19), andsend (X108; X222; X396) an instruction to at least some of a number of compensation handling devices (26) to make the inverter (28) of the corresponding enhanced power distribution network (10) act according to at least one of the roles for stabilising the power grid (16, 18) in the region (19), and each compensation handling device (26) comprising a processor (34) operative to: obtain (X100; X200; X310, X350) a time of a central clock(TO), obtain (X104; X204; X316, X360) a time of a crossing of a reference level of a phase at the enhanced power distribution network (10), determine (X105; X206; X317; X361) a first time offset (T1) from the central clock as a difference in time between the time of the crossing of the reference level and the time (TO) of the central clock, receive (X108; X222; X396), from the compensation control device (22), the instruction to act in at least one of the roles, and order (X110, X224, X397) the corresponding inverter (28) to act in the at least one instructed role with a timing that is based on the central clock (TO) adjusted with the first time offset (T1).

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