An electric charging system and a method for controlling the same

Abstract

An electric charging system for electric vehicles comprises a direct voltage bus (101), one or more alternating voltage - direct voltage converters (102, 103) to transfer energy between a supply grid (104) and the direct voltage bus, direct voltage devices (105-112) comprising direct voltage converters (105-110) to transfer energy between the direct voltage bus and charging supply devices (113), and an energy management system (117) configured to allocate available power to the direct voltage devices in accordance with charging power demands of electric vehicles connected to the charging supply devices The direct voltage bus comprises protector elements (118-122) each breaking electric current through the protector element in response to violation of protection attributes of the protector element. The electric charging system comprises a protection control system (123) connected to the energy management system and to the protector elements and configured to update the protection attributes in accordance with changes in the power allocation and / or in electrical selectivity effecting characteristics.

Description

[0001] An electric charging system and a method for controlling the same

[0002] Field

[0003] The invention relates generally to charging of electric vehicles. More particularly, the invention relates to an electric charging system for charging electric vehicles such as e.g. electric trucks, electric vans, electric cars, electric watercrafts, and / or electric aircrafts. Furthermore, the invention relates to a method and to a computer program for controlling an electric charging system that is suitable for charging electric vehicles.

[0004] Background

[0005] Like in any electric systems, faults may occur in an electric charging system for charging electric vehicles. A fault may take place in components of an electric charging system such as alternating voltage - direct voltage “AC / DC” converters, direct voltage “DC” converters, relays, cables, wires, etc. It is also possible that a fault occurs in an electric vehicle connected to an electric charging system, and the electric charging system needs to react to the fault of the vehicle in a suitable way. A fault can be for example a short circuit between poles of a direct voltage element or between phases of an alternating voltage element, or a ground fault between a direct voltage pole and the ground or between an alternating voltage phase and the ground. As a safety measure against faults of the kind mentioned above, an electric charging system is typically provided with a protection system that may comprise, for example, fuses, electronic circuit breaker “ECB” based on solid-state switches, electromechanical relays, and / or other protector elements.

[0006] A protection system of an electric charging system should act selectively so that only an element or elements of the electric charging system whose separation from the rest of the electric charging system is necessary and sufficient to isolate a fault from the rest of the electric charging system is / are separated by the protection system in response to the fault. In other words, the protection system should not separate such elements whose separation is not necessary for the isolation of the fault. Furthermore, the protection system should be able to distinguish faults frome.g. transients which may take place just after switching actions within the electric charging system and from other phenomena that may occur during normal operation. Especially, high-impedance “Hi-Z” faults can be challenging to distinguish from phenomena which may occur during normal operation. Elements of the electric charging system which are free from faults are typically wanted to be operating through a fault period i.e. a time interval starting at the beginning of a fault and ending at separation of a faulty part from the rest of the system. Therefore, a fault ride through “FRT” capability is a desired property of an electric charging system. A further challenge is disturbances in alternating voltage power availability due to supply grid faults and / or disturbances, leading to low voltage conditions i.e. voltage sags. A low voltage ride through ability is also a desired property of an electric charging system.

[0007] Also, there can be situations where a distribution bus has parts or branches which have different abilities to provide fault current to timely separate itself from the rest of the system should a fault occur, which can then disturb other parts or branches of the system. This leads to a need for better selectivity measures to take into account varying electrical characteristics of each part or branch. Also, as a typical last measure against e.g. catastrophic fault current, fault current protection relies on utilization of fuses, the tripping of which causes unwanted downtime and should be avoided is possible. For example, in the case of a MW power range battery energy storage, a fault current peak can reach hundreds of kiloamperes that can be ~100 x the nominal current. This can cause significant damage to a busbar and / or a cabling support system and should be avoided. On the other end of the spectrum, a photovoltaic “PV” array can be produce only few ten percent more current to short circuit than a nominal current, ~1 ,2-1 ,4 x the nominal current, which then makes a fault trip time either very long or the fault trip might not even be possible with the energy from the PV array.

[0008] Summary

[0009] The following presents a simplified summary to provide a basic understanding of some embodiments of the invention. The summary is not an extensive overview of the invention. It is neither intended to identify key or critical elements of the inventionnor to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of exemplifying embodiments.

[0010] In accordance with the invention, there is provided a new electric charging system for charging electric vehicles. In this document, the term “electric vehicle” covers not only full-electric vehicles but also pluggable hybrid vehicles which comprise both one or more electric motors and a combustion engine.

[0011] An electric charging system according to the invention comprises:

[0012] - a direct voltage bus,

[0013] - one or more alternating voltage - direct voltage “AC / DC” converters configured to transfer energy between an alternating voltage supply grid and the direct voltage bus,

[0014] - direct voltage devices connected to the direct voltage bus, one or more of the direct voltage devices being one or more direct voltage “DC” converters configured to transfer energy between the direct voltage bus and one or more charging supply devices each having a vehicle coupling interface connectable to an electric vehicle, and

[0015] - an energy management system “EMS” configured to allocate power available at the direct voltage bus to the direct voltage devices in accordance with at least charging power demand or demands of one or more electric vehicles connected to the one or more charging supply devices.

[0016] The above-mentioned direct voltage bus comprises protector elements each configured to break electric current through the protector element in response to violation of one or more protection attributes, e.g. an overcurrent trip limit, of the protector element. The electric charging system comprises a protection control system communicatively connected to the energy management system and to the protector elements. The protection control system is configured to update at least part of the protection attributes of the protector elements in accordance with at least one of the following: i) changes in the allocation of the power available at the directvoltage bus to the direct voltage devices and ii) changes of electrical selectivity effecting characteristics of at least one part of the direct voltage bus.

[0017] The above-mentioned energy management system “EMS” can be, for example, a local control system, or a combination of a local control system and a remote cloud service and communication between these two. Thus, the invention is not limited to any specific architecture of the energy management system.

[0018] The adaptation of the protection attributes in accordance with the power allocation may improve the selectivity as well as the ability to distinguish faults from phenomena which may occur during normal operation. For example, a 100 A electric current supplied to a DC converter may indicate a fault in the DC converter and / or in an electric vehicle connected to the DC converter when power allocated to be transferred by the DC converter is e.g. 10 kW, whereas the 100 A electric current can be normal when the allocated power is e.g. 50 kW. The protection attributes may comprise, for example, an overcurrent trip limit, an overvoltage trip limit, an undervoltage trip limit, a time-current curve, and / or other fault criteria. Furthermore, the protection attributes may indicate direction sensitivity so that e.g. electric current in one direction through a protector element can be deemed to be normal, whereas electric current in the opposite direction can be deemed to indicate a fault. A direction sensitive protector element can be used e.g. with a photovoltaic “PV” array that, when being in a normal condition, produces electric energy but does not consume it.

[0019] In accordance with the invention, there is also provided a new method for controlling an electric charging system of the kind described above. The method comprises:

[0020] - receiving status data expressing at least one of the following: i) allocation of the power available at the direct voltage bus to the direct voltage devices and ii) electrical selectivity effecting characteristics of at least one part of the direct voltage bus, and

[0021] - updating at least part of the protection attributes of the protector elements in accordance with at least one of the following: i) changes in the allocation of the power available at the direct voltage bus to the direct voltage devices and ii)changes in the electrical selectivity effecting characteristics of the at least one part of the direct voltage bus.

[0022] In accordance with the invention, there is also provided a new computer program for controlling an electric charging system of the kind described above. The computer program comprises computer executable instructions for controlling a programmable data processing system to:

[0023] - receive status data expressing at least one of the following: i) allocation of the power available at the direct voltage bus to the direct voltage devices and ii) electrical selectivity effecting characteristics of at least one part of the direct voltage bus, and

[0024] - update at least part of the protection attributes of the protector elements in accordance with at least one of the following: i) changes of the allocation of the power available at the direct voltage bus to the direct voltage devices and ii) changes in the electrical selectivity effecting characteristics of the at least one part of the direct voltage bus.

[0025] In accordance with the invention, there is also provided a new computer program product. The computer program product comprises a non-volatile computer readable medium, e.g. a compact disc “CD”, encoded with a computer program according to the invention.

[0026] Exemplifying and non-limiting embodiments are described in accompanied dependent claims.

[0027] Various exemplifying and non-limiting embodiments both as to constructions and to methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplifying and nonlimiting embodiments when read in conjunction with the accompanying drawings.

[0028] The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of un-recited features.The features recited in dependent claims are mutually freely combinable unless otherwise explicitly stated.

[0029] Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.

[0030] Brief description of figures

[0031] Exemplifying and non-limiting embodiments and their advantages are explained in greater detail below in the sense of examples and with reference to the accompanying drawings, in which:

[0032] Figure 1 illustrates an electric charging system according to an exemplifying and non-limiting embodiment

[0033] Figure 2 illustrates an electric charging system according to an exemplifying and non-limiting embodiment,

[0034] Figure 3 illustrates an electric charging system according to an exemplifying and non-limiting embodiment, and

[0035] Figure 4 shows a flowchart of a method according to an exemplifying and nonlimiting embodiment for controlling an electric charging system.

[0036] Description of exemplifying and non-limiting embodiments

[0037] The specific examples provided in the description below should not be construed as limiting the scope and / or the applicability of the invention. Lists and groups of examples provided in the description are not exhaustive unless otherwise explicitly stated.

[0038] Figure 1 illustrates an electric charging system according to an exemplifying and non-limiting embodiment for charging electric vehicles. The electric charging system comprises a direct voltage “DC” bus 101. In this exemplifying case, the DC bus 101 is a three-pole system having a positive pole DC+, a negative pole DC-, and a zero pole. In this exemplifying case, the zero pole is grounded but it is also possible that the zero pole is ungrounded. The electric charging system comprises alternatingvoltage - direct voltage “AC / DC” converters 102 and 103 configured to transfer energy between an alternating voltage “AC” supply grid 104 and the direct voltage bus 101. In this exemplifying case, each of the AC / DC converters 102 and 103 is connected to the AC supply grid 104 via a converter-specific transformer, but it is also possible that the AC / DC converters are connected to the AC supply grid 104 via a common transformer, or, depending on voltage levels, via filter elements. The electric charging system comprises direct voltage “DC” devices 105, 106, 107, 108, 109, 110, 111, and 112 connected to the DC bus 101 , where the DC devices 105-110 are direct voltage “DC” converters configured to transfer energy between the DC bus 101 and charging supply devices each having a vehicle coupling interface. In figure 1, three of the charging supply devices are denoted with references 113, 135, and 136 and the vehicle coupling interface of the charging supply device 113 is denoted with reference 114. In this exemplifying case, the charging supply devices are charging cables and the vehicle coupling interfaces are charging plugs each being connectable to a charging socket of an electric vehicle, but different charging supply devices and vehicle coupling interfaces, such as e.g. pantographs, automatic couplers e.g. robotic arms, wireless charging pads, etc., are also possible. In this exemplifying electric charging system, the DC device 111 comprises a battery energy storage 130 and a DC converter 131, and the DC device 112 comprises a photovoltaic “PV” array 132 and a photovoltaic DC converter 133. It is also possible that the battery energy storage 130 is connected to the DC bus 101 without the DC converter 131, if the battery energy storage 130 and the DC bus 101 have a same voltage level. The battery energy storage 130 and / or the PV array 132 may comprise internal protection elements, e.g. fuses, which are not shown in figure 1. The battery energy storage 130 and / or the PV array 132 may comprise multiple cells / modules / panels in series and / or in parallel, and may comprise protection elements depending on the topology.

[0039] The electric charging system comprises an energy management system “EMS” 117 configured to dynamically allocate power available at the DC bus 101 to the DC devices 105-111 in accordance with at least charging power demand or demands of one or more electric vehicles connected to the charging supply devices. In the exemplifying situation shown in figure 1, two of the charging supply devices areconnected to electric vehicles 115 and 116, respectively. The power available at the DC bus 101 can be dependent on maximum power available from the AC supply grid 104, price of energy available from the AC supply grid 104, power transfer capacities of the AC / DC converters 102 and 103, power produced by the photovoltaic array 132, and a charging state of the battery energy storage 130. Depending on the price of energy available from the AC supply grid 104 and on the charging state of the battery energy storage 130, the EMS 117 may allocate a part of the power received from the AC supply grid 104 and / or from the photovoltaic array 132 to charge the battery energy storage 130.

[0040] The DC bus 101 comprises protector elements 118, 119, 120, 121, and 122 each of which is configured to break electric current through the protector element in response to violation of one or more protection attributes of the protector element. The protection attributes may comprise, for example, an overcurrent trip limit, an overvoltage trip limit, an undervoltage trip limit, a low impedance, i.e. voltage-current ratio, trip limit, a time-current curve that depicts time required for a protector element to break electric current at a given fault current level, and / or one or more other fault criteria. The protection attributes can be direction sensitive so that, for example, an overcurrent trip limit is dependent on the direction of electric current through a protector element. For example, an overcurrent trip limit of the protector element 121 can be significantly higher for electric current directed so that power flows from the PV array 132 than for electric current in the opposite direction because the PV array 132, when being in a normal condition, produces electric energy but does not consume it. Therefore, the system advantageously takes into account power allocation for each protector element and the electric characteristics of the portion of the circuit which is protected by the protector element when setting protection attributes for the protector element. The protector elements 118-122 can be, for example, electronic circuit breakers “ECB” based on silicon-carbide “SiC” junction field-effect transistor “JFET” technology or some other suitable technology. Furthermore, the electric charging system comprises protector elements 137 and 138 each of which is configured to separate a respective one of the AC / DC converters 102 and 103 from the AC supply grid 104 in response to violation of one or more protection attributes of the protector element.One or more of the protector elements 118-122 can be configured to have a reconnection functionality such that after a protector element has tripped and thus separated a part of the electric charging system from the rest of the electric charging system, the protector element reconnects the separated part to the rest of the electric charging system, and, if a fault is still on, the protector element gets tripped again. Each of the protector elements can be configured to make delayed reconnections so that a delay from a trip event to a subsequent attempt to reconnect is increased after each failed reconnection in which the protector element gets tripped again. There can be, for example, a quick reconnection shortly after a trip event and a time reconnection after a longer delay that starts to elapse if the quick reconnection fails i.e. the fault is still on just after the quick reconnection. A reconnection may comprise a current limitation functionality for example so that current is allowed to gradually rise during the reconnection to avoid uncontrolled current peaks during the reconnection especially in cases in which there can be a voltage difference between parts of the system to be reconnected.

[0041] The electric charging system comprises a protection control system 123 that is communicatively connected to the energy management system “EMS” 117 and to the protector elements 118-122. Communication can be directly established between the protection control system 123 and the energy management system 117 or through a local and / or global communication network of the electric charging system. The protection control system 123 configured to receive, from the EMS 117 and / or from one or more other controllers of the electric charging system, status data expressing allocation of the power available at the DC bus 101 to the DC devices 105-111 and / or electrical selectivity effecting characteristics of at least one part of the direct voltage bus. The above-mentioned one or more other controllers may comprise, for example, controllers of the DC converters, controllers of the protector elements, charger controllers, and / or other local system controllers.

[0042] The protection control system 123 is configured to dynamically update at least part of the above-mentioned protection attributes of the protector elements 118-122 in accordance with changes in the allocation of the power available at the DC bus 101 to the DC devices 105-111 and / or in accordance with changes in the electrical selectivity effecting characteristics of at least one part of the DC bus 101. Theadaptation of the protection attributes in accordance with the power allocation may improve the selectivity of protection, an ability of the protection to distinguish faults from phenomena which may occur during normal operation, and a fault ride through capability of the electric charging system. For example, a 100 A electric current supplied to a DC converter may indicate a fault in the DC converter and / or in an electric vehicle connected to the DC converter when power allocated to be transferred by the DC converter is e.g. 10 kW, whereas the 100 A electric current can be normal when the allocated power is e.g. 50 kW. The above-mentioned electrical selectivity effecting characteristics may comprise for example a state of charge “SOC” and / or voltage of a battery energy storage and / or voltage of a capacitive energy storage. When the SOC and / or the voltage is above a given level, the battery energy storage can supply fault current capable of causing one or more protector elements to separate a faulty part of the system from the rest of the system, whereas when the SOC and / or the voltage is low, the tripping limits need to be tuned lower to provide a sufficient selectivity. For another example, the above-mentioned electrical selectivity effecting characteristics may comprise data expressing which one or ones of the DC devices are active in the DC bus and thus capable of supplying fault current to a fault point and which one or ones of the DC devices are under maintenance or otherwise not capable of supplying fault current to a fault point.

[0043] In the exemplifying electric charging system illustrated in figure 1, the protector elements 118-121 are located in front of the DC devices so that each of these protector elements is configured to separate one or more of the DC devices from the DC bus 101 in response to a situation in which behavior of at least one of following violates the protection attributes of the protector element: electric current through the protector element and direct voltage of the protector element. The protector element 118 is configured to separate the DC converters 105-107 when the protector element 118 trips, the protector element 119 is configured to separate the DC converters 108-110 when the protector element 119 trips, the protector element 120 is configured to separate the DC device 111 comprising the battery energy storage 130 when the protector element 120 trips, and the protector element 121 is configured to separate the DC device 112 comprising the PV array 132 whenthe protector element 121 trips. The protector element 122 is located between parts 124 and 125 of the DC bus 101. The protector element 122 is configured to divide the DC bus 101 into electrically separate parts in response to a situation in which behavior of at least one of following violates the protection attributes of the protector element 122: electric current through the protector element and direct voltage of the protector element. Thus, in a case where there is / are a severe fault or faults in one half of the electric charging system, the other half of electric charging system may be still used.

[0044] In the exemplifying electric charging system illustrated in figure 1 , the DC converters 105-107 are connected to the DC bus 101 via the protector element 118, and each of the DC converters 105-107 is provided with an overcurrent protector configured to disconnect the DC converter from the protector element 118 in response to a situation in which temporal behavior of electric current of the overcurrent protector exceeds a time-current curve of the overcurrent protector. In figure 1 , an overcurrent protector of the DC converter 107 is denoted with reference 126. Correspondingly, the DC converters 108-110 are connected to the DC bus 101 via the protector element 119, and each of the DC converters 108-110 is provided with an overcurrent protector configured to disconnect the DC converter from the protector element 119 in response to a situation in which temporal behavior of electric current of the overcurrent protector exceeds a time-current curve of the overcurrent protector. Correspondingly, the DC device 112 is provided with an overcurrent protector configured to disconnect the DC converter from the protector element 121 in response to a situation in which temporal behavior of electric current of the overcurrent protector exceeds a time-current curve of the overcurrent protector. The overcurrent protectors can be for example fuses.

[0045] The exemplifying electric charging system illustrated in figure 1 comprises a switch array 134 between the DC converters 105-107 and the charging supply devices 113, 135, and 136. Correspondingly, the electric charging system comprises a switch array between the DC converters 108-110 and the respective charging supply devices. Each switch array can be controlled by e.g. a charger controller that is communicatively connected to the energy management system “EMS” 117 directly or through a local and / or global communication network of the electric chargingsystem. The switch arrays can be controlled in accordance with the charging power demand or demands of one or more electric vehicles connected to one or more of the charging supply devices. The charger controller is not shown in figure 1.

[0046] The exemplifying electric charging system illustrated in figure 1 comprises an energy storage 127 connected to electric conductors from the protector element 118 to the DC converters 105-107. The energy storage 127 is configured to supply electric current to a fault point within or after one of the DC converters 105-107 to cause the overcurrent protector of the one of the DC converters 105-107 to separate the fault point from the protector element 118 and from the other ones of the DC converters 105-107. Thus, the energy storage 127 improves the selectivity of the protection when there is a fault within one of the DC converters 105-107 and / or in an electric vehicle connected to this one of the DC converters 105-107. Correspondingly, the electric charging system comprises an energy storage 128 connected to electric conductors from the protector element 119 to the DC converters 108-110 and an energy storage 129 connected to electric conductors from the protector element 121 to the DC device 112. Each of the energy storages 127-129 may comprise one or more capacitor elements. The existence of the energy storage and its effect to selectivity of the part of the DC bus is advantageously taken into account when protection attributes for the part of the DC bus are selected. These protection attributes can be fixed electrical characteristics for a given part of the DC bus. For example, if a part of the DC bus has an ability to independently clear a fault, the protection attributes can be set accordingly. If the part is unable to independently clear a fault, the protection attribute must be set in such a way that needed fault current is allowed to flow via the protection element before tripping.

[0047] Figure 2 illustrates an electric charging system according to an exemplifying and non-limiting embodiment for charging electric vehicles. The electric charging system comprises a direct voltage “DC” bus 201 having a star-topology. In this exemplifying case, the DC bus 201 is a two-pole system having a positive pole DC+ with a higher electric potential and a zero pole with a lower electric potential. In this exemplifying case, the zero pole is grounded but it is also possible that the zero pole is ungrounded. It is also possible that the positive pole having the higher electric potential is grounded and the pole having the lower electric potential is ungrounded.The electric charging system comprises alternating voltage - direct voltage “AC / DC” converters 202 and 203 configured to transfer energy between an alternating voltage “AC” supply grid 204 and the direct voltage bus 201. In this exemplifying case, each of the AC / DC converters 202 and 203 is connected to the AC supply grid 204 via a converter-specific transformer. The electric charging system comprises direct voltage “DC” devices 205, 206, 207, 208, 209, 210, 211, and 212 connected to the DC bus 201, where the DC devices 205-210 are direct voltage “DC” converters configured to transfer energy between the DC bus 201 and charging supply devices each having a vehicle coupling interface. In figure 2, one of the charging supply devices is denoted with reference 213 and the vehicle coupling interface of the charging supply device 213 is denoted with reference 214.

[0048] The electric charging system comprises an energy management system “EMS” 217 configured to dynamically allocate power available at the DC bus 201 to the DC devices 205-211 in accordance with at least charging power demand or demands of one or more electric vehicles connected to the charging supply devices. In the exemplifying situation shown in figure 2, two of the charging supply devices are connected to electric vehicles 215 and 216, respectively.

[0049] The DC bus 201 comprises protector elements 218, 219, 220, 221, 222, and 242 each of which is configured to break electric current through the protector element in response to violation of one or more protection attributes of the protector element. One or more of the protector elements can be configured to have a reconnection functionality such that after a protector element has tripped and thus separated a part of the electric charging system from the rest of the electric charging system, the protector element reconnects the separated part to the rest of the electric charging system, and, if a fault is still on, the protector element gets tripped again. There can be, for example, a quick reconnection shortly after a trip event and a time reconnection after a longer delay that starts to elapse if the quick reconnection fails.

[0050] The electric charging system comprises a protection control system 223 that is communicatively connected to the energy management system “EMS” 217 and to the protector elements 218-222 and 242. The protection control system 223 is configured to receive, from the EMS 217, status data expressing allocation of thepower available at the DC bus 201 to the DC devices 205-211 and / or electrical selectivity effecting characteristics of at least one part of the DC bus 201. The protection control system 223 configured to dynamically update at least part of the above-mentioned protection attributes of the protector elements 218-222 and 242 in accordance with changes in the allocation of the power available at the DC bus 201 to the DC devices 205-211.

[0051] The exemplifying electric charging system illustrated in figure 2 comprises an energy storage 227 connected to electric conductors from the protector element 218 to the DC converters 205-207. The energy storage 227 is configured to supply electric current to a fault point within or after one of the DC converters 205-207 to cause an overcurrent protector, e.g. a fuse, of the one of the DC converters 205-207 to separate the fault point from the protector element 218 and from the other ones of the DC converters 205-207. Correspondingly, the electric charging system comprises an energy storage 228 connected to electric conductors from the protector element 219 to the DC converters 208-210 and an energy storage 229 connected to electric conductors from the protector element 221 to the DC device 212.

[0052] Figure 3 illustrates an electric charging system according to an exemplifying and non-limiting embodiment for charging electric vehicles. The electric charging system comprises a direct voltage “DC” bus 301 having a ring-topology. In this exemplifying case, the DC bus 201 is a two-pole system having a positive pole DC+ and a negative pole DC-. In this exemplifying case, both the positive and the negative poles are ungrounded, but it is also possible that one of these poles is grounded. The electric charging system comprises alternating voltage - direct voltage “AC / DC” converters 302 and 303 configured to transfer energy between an alternating voltage “AC” supply grid 304 and the direct voltage bus 301. In this exemplifying case, each of the AC / DC converters 302 and 303 is connected to the AC supply grid 304 via a converter-specific transformer. The electric charging system comprises direct voltage “DC” devices 305, 306, 307, 308, 309, 310, 311, and 312 connected to the DC bus 301, where the DC devices 305-310 are direct voltage “DC” converters configured to transfer energy between the DC bus 301 and charging supply devices each having a vehicle coupling interface. In figure 3, one of thecharging supply devices is denoted with reference 313 and the vehicle coupling interface of the charging supply device 313 is denoted with reference 314.

[0053] The electric charging system comprises an energy management system “EMS” 317 configured to dynamically allocate power available at the DC bus 301 to the DC devices 305-311 in accordance with at least charging power demand or demands of one or more electric vehicles connected to the charging supply devices. In the exemplifying situation shown in figure 3, two of the charging supply devices are connected to electric vehicles 315 and 316, respectively.

[0054] The DC bus 301 comprises protector elements 318, 319, 320, 321, 322, and 342 each of which is configured to break electric current through the protector element in response to violation of one or more protection attributes of the protector element. One or more of the protector elements can be configured to have a reconnection functionality such that after a protector element has tripped and thus separated a part of the electric charging system from the rest of the electric charging system, the protector element reconnects the separated part to the rest of the electric charging system, and, if a fault is still on, the protector element gets tripped again. The protector elements 318-321 are between the ring-shaped DC bus 301 and the DC devices 305-312. The protector elements 322 and 342 are located between parts 324 and 325 of the ring-shaped DC bus 301. The protector elements 322 and 324 are configured to divide the DC bus 301 into electrically separate parts in response to a situation in which behavior of at least one of following violates the protection attributes of the protector elements 322 and 342: electric current through the protector element and direct voltage of the protector element. Thus, in a case where there is / are a severe fault or faults in one half of the electric charging system, the other half of electric charging system may still be used.

[0055] The electric charging system comprises a protection control system 323 that is communicatively connected to the energy management system “EMS” 317 and to the protector elements 318-322 and 342. The protection control system 323 configured to receive, from the EMS 317, status data expressing allocation of the power available at the DC bus 301 to the DC devices 305-311 and / or electrical selectivity effecting characteristics of at least one part of the DC bus 301. Theprotection control system 323 is configured to dynamically update at least part of the above-mentioned protection attributes of the protector elements 318-322 and 342 in accordance with changes in the allocation of the power available at the DC bus 301 to the DC devices 305-311.

[0056] The exemplifying electric charging system illustrated in figure 3 comprises an energy storage 327 connected to electric conductors from the protector element 318 to the DC converters 305-307. The energy storage 327 is configured to supply electric current to a fault point within or after one of the DC converters 305-307 to cause an overcurrent protector, e.g. a fuse, of the one of the DC converters 305-307 to separate the fault point from the protector element 318 and from the other ones of the DC converters 305-307. Correspondingly, the electric charging system comprises an energy storage 328 connected to electric conductors from the protector element 319 to the DC converters 308-310 and an energy storage 329 connected to electric conductors from the protector element 321 to the DC device 312.

[0057] The implementation of each of the energy management systems 118, 217, and 317 shown in figures 1-3 as well as the implementation of each of the protection control systems 123, 223, and 323 shown in figures 1-3 can be based on one or more analogue circuits, one or more digital processing circuits, or a combination thereof. Each digital processing circuit can be a programmable processor circuit provided with appropriate software, a dedicated hardware processor such as for example an application specific integrated circuit “ASIC”, or a configurable hardware processor such as for example a field programmable gate array “FPGA”. Furthermore, each of the energy management systems and each of the protection control systems may comprise one or more memory circuits each of which can be for example a randomaccess memory “RAM” circuit or a flash memory circuit. Each of the energy management systems can be a local controller or a combination of a local controller and a remote cloud service.

[0058] It is worth noting that the above-described principle based on the energy storages 127-129, 227-229, and 327-329 for improving the functionality of the protection is also applicable in electric charging systems where the protection attributes of theprotector elements are not necessarily adapted in accordance with i) changes in allocation of available power to direct voltage devices and / or ii) changes in electrical selectivity effecting characteristics of at least one part of the direct voltage bus. An electric charging system according to an exemplifying and non-limiting embodiment where the above-mentioned principle is applied comprises:

[0059] - a direct voltage bus,

[0060] - one or more alternating voltage - direct voltage converters configured to transfer energy between an alternating voltage supply grid and the direct voltage bus,

[0061] - direct voltage devices connected to the direct voltage bus, one or more of the direct voltage devices being one or more direct voltage converters configured to transfer energy between the direct voltage bus and one or more charging supply devices each having a vehicle coupling interface,

[0062] - protector elements in the direct voltage bus, each of the protector elements being configured to break electric current through the protector element in response to violation of one or more protection attributes of the protector element, and a first one or ones of the direct voltage devices is / are connected to the direct voltage bus via one of the protector elements and each of the first one or ones of the direct voltage devices is provided with an overcurrent protector configured to disconnect the direct voltage device from the one of the protector elements in response to a situation in which temporal behavior of electric current of the overcurrent protector exceeds a time-current curve of the overcurrent protector, and

[0063] - an energy storage connected to electric conductors from the one of the protector elements to the first one or ones of the direct voltage devices, and configured to supply electric current to a fault point within or after one of the first one or ones of the direct voltage converters to cause the overcurrent protector of the one of the first one or ones of the direct voltage devices to separate the fault point from the one of the protector elements.In an electric charging system according to an exemplifying and non-limiting embodiment where the above-mentioned principle is applied, each of the overcurrent protectors is a fuse.

[0064] In an electric charging system according to an exemplifying and non-limiting embodiment where the above-mentioned principle is applied, the energy storage comprises one or more capacitor elements.

[0065] In an electric charging system according to an exemplifying and non-limiting embodiment where the above-mentioned principle is applied, the protector elements are electronic circuit breakers.

[0066] The electric charging system where the above-mentioned principle is applied may, however, comprise an energy management system configured to allocate power available at the direct voltage bus to the direct voltage devices in accordance with at least charging power demand or demands of one or more electric vehicles connected to the one or more charging supply devices. Furthermore, the electric charging system may comprise a protection control system communicatively connected to the energy management system and to the protector elements and configured to update at least part of the protection attributes of the protector elements in accordance with changes of allocation of the power available at the direct voltage bus to the direct voltage devices.

[0067] In an electric charging system according to an exemplifying and non-limiting embodiment where the above-mentioned principle is applied, first ones of the protector elements are located in front of the direct voltage devices so that each of the first ones of the protector elements is configured to separate one or more of the direct voltage devices from the direct voltage bus in response to a situation in which behavior of at least one of following violates the protection attributes of the protector element: electric current through the protector element and direct voltage of the protector element. When the electric charging system comprises the above-mentioned energy management system and the protection control system, the protection control system is advantageously configured to update an overcurrent trip limit and / or a time-current curve of each of the first ones of the protector elementsin accordance with the power allocated to the one or more direct voltage devices connected to the direct voltage bus via the protector element.

[0068] In an electric charging system according to an exemplifying and non-limiting embodiment where the above-mentioned principle is applied, a second one or ones of the protector elements are located between parts of the direct voltage bus, and each of the second one or ones of the protector elements is configured to divide the direct voltage bus into electrically separate parts in response to a situation in which behavior of at least one of following violates the protection attributes of the protector element: electric current through the protector element and direct voltage of the protector element.

[0069] An electric charging system according to an exemplifying and non-limiting embodiment where the above-mentioned principle is applied comprises a switch array between two or more of the direct voltage converters and two or more of the charging supply devices, and a controller configured to control the switch array in accordance with a charging power demand or demands of one or more electric vehicles connected to one or more of the charging supply devices connected to the switch array.

[0070] Figure 4 shows a flowchart of a method according to an exemplifying and nonlimiting embodiment for controlling an electric charging system that comprises:

[0071] - a direct voltage bus,

[0072] - one or more alternating voltage - direct voltage converters configured to transfer energy between an alternating voltage supply grid and the direct voltage bus,

[0073] - direct voltage devices connected to the direct voltage bus, one or more of the direct voltage devices being one or more direct voltage converters configured to transfer energy between the direct voltage bus and one or more charging supply devices each having a vehicle coupling interface,

[0074] - an energy management system configured to allocate power available at the direct voltage bus to the direct voltage devices in accordance with at leastcharging power demand or demands of one or more electric vehicles connected to the one or more charging supply devices, and

[0075] - protector elements, e.g. electronic circuit breakers, in the direct voltage bus, each configured to break electric current through the protector element in response to violation of one or more protection attributes of the protector element.

[0076] The method comprises the following actions:

[0077] - action 401 : receiving, from the energy management system and / or from one or more other controllers of the electric charging system, status data expressing at least one of following: i) allocation of the power available at the direct voltage bus to the direct voltage devices and ii) electrical selectivity effecting characteristics of at least one part of the direct voltage bus, and

[0078] - action 402: updating at least part of the protection attributes of the protector elements in accordance with at least one of the following: i) changes of the allocation of the power available at the direct voltage bus to the direct voltage devices and ii) changes of the electrical selectivity effecting characteristics of the at least one part of the direct voltage bus.

[0079] In a method according to an exemplifying and non-limiting embodiment, first ones of the protector elements are located in front of the direct voltage devices so that each of the first ones of the protector elements is configured to separate one or more of the direct voltage devices from the direct voltage bus in response to a situation in which behavior of at least one of following violates the protection attributes of the protector element: electric current through the protector element direct voltage between current carrying poles of the protector element, and direct voltage between current a carrying pole of the protector element and ground.

[0080] A method according to an exemplifying and non-limiting embodiment comprises updating an overcurrent trip limit of each of the first ones of the protector elements in accordance with the power allocated to the one or more direct voltage devices connected to the direct voltage bus via the protector element.A method according to an exemplifying and non-limiting embodiment comprises updating a time-current curve of each of the first ones of the protector elements in accordance with the power allocated to the one or more direct voltage devices connected to the direct voltage bus via the protector element.

[0081] In a method according to an exemplifying and non-limiting embodiment, second one or ones of the protector elements are located between parts of the direct voltage bus, and the second one or ones of the protector elements is / are configured to divide the direct voltage bus into electrically separate parts in response to a situation in which behavior of at least one of following violates the protection attributes of the protector element: electric current through the protector element, direct voltage between current carrying poles of the protector element, and direct voltage between current a carrying pole of the protector element and ground.

[0082] In a method according to an exemplifying and non-limiting embodiment, first one or ones of the direct voltage devices are connected to the direct voltage bus via one of the protector elements and each of the first one or ones of the direct voltage devices is provided with an overcurrent protector configured to disconnect the direct voltage devices from the one of the protector elements in response to a situation in which temporal behavior of electric current of the overcurrent protector exceeds a timecurrent curve of the overcurrent protector. The overcurrent protector can be e.g. a fuse.

[0083] In a method according to an exemplifying and non-limiting embodiment, the electric charging system comprises an energy storage connected to electric conductors from the one of the protector elements to the first one or ones of the direct voltage devices, and the method comprises supplying electric current from the energy storage to a fault point within or after one of the first one or ones of the direct voltage devices to cause the overcurrent protector of the one of the first one or ones of the direct voltage devices to separate the fault point from the one of the protector elements. The energy storage may comprise e.g. one or more capacitor elements.

[0084] In a method according to an exemplifying and non-limiting embodiment, at least one of the direct voltage devices comprises a battery energy storage connected to the direct voltage bus via one of the protector elements.In a method according to an exemplifying and non-limiting embodiment, at least one of the direct voltage devices comprises a photovoltaic array and a photovoltaic direct voltage converter connected to the direct voltage bus via one of the protector elements.

[0085] In a method according to an exemplifying and non-limiting embodiment, the electric charging system comprises a switch array between the direct voltage converters and the charging supply devices, and the method comprises controlling the switch array in accordance with the charging power demand or demands of one or more electric vehicles connected to one or more of the charging supply devices.

[0086] A computer program according to an exemplifying and non-limiting embodiment comprises computer executable instructions for controlling a programmable data processing system to carry out actions related to a method according to any of the above-described exemplifying and non-limiting embodiments.

[0087] A computer program according to an exemplifying and non-limiting embodiment comprises software modules for controlling an electric charging system that comprises:

[0088] - a direct voltage bus,

[0089] - one or more alternating voltage - direct voltage converters configured to transfer energy between an alternating voltage supply grid and the direct voltage bus,

[0090] - direct voltage devices connected to the direct voltage bus, one or more of the direct voltage devices being one or more direct voltage converters configured to transfer energy between the direct voltage bus and charging supply devices each having a vehicle coupling interface,

[0091] - an energy management system configured to allocate power available at the direct voltage bus to the direct voltage devices in accordance with at least charging power demand or demands of one or more electric vehicles connected to the charging supply devices, and- protector elements, e.g. electronic circuit breakers, in the direct voltage bus, each configured to break electric current through the protector element in response to violation of one or more protection attributes of the protector element.

[0092] The software modules comprise computer executable instructions for controlling a programmable data processing system to:

[0093] - receive, from the energy management system and / or from one or more other controllers of the electric charging system, status data expressing at least one of following: i) allocation of the power available at the direct voltage bus to the direct voltage devices and ii) electrical selectivity effecting characteristics of at least one part of the direct voltage bus, and

[0094] - update at least part of the protection attributes of the protector elements in accordance with at least one of following: i) changes in the allocation of the power available at the direct voltage bus to the direct voltage devices and ii) changes of the electrical selectivity effecting characteristics of the at least one part of the direct voltage bus.

[0095] The software modules can be for example subroutines or functions implemented with programming tools compatible with the programmable data processing system.

[0096] A computer program product according to an exemplifying and non-limiting embodiment comprises a computer readable medium, e.g. a compact disc “CD”, encoded with a computer program according to an exemplifying embodiment of invention.

[0097] A non-volatile computer readable medium according to an exemplifying and nonlimiting embodiment is encoded with a computer program according to an exemplifying embodiment of invention.

[0098] A signal according to an exemplifying and non-limiting embodiment is encoded to carry information defining a computer program according to an exemplifying embodiment of invention.The specific examples provided in the description given above should not be construed as limiting the scope and / or the applicability of the invention. Lists and groups of examples provided in the description given above are not exhaustive unless otherwise explicitly stated.

Claims

What is claimed is:

1. An electric charging system for charging electric vehicles, the electric charging system comprising:- a direct voltage bus (101, 201 , 301 ),- one or more alternating voltage - direct voltage converters (102, 103, 202, 203, 302, 303) configured to transfer energy between an alternating voltage supply grid (104, 204, 304) and the direct voltage bus,- direct voltage devices (105-112, 205-212, 305-312) connected to the direct voltage bus, one or more of the direct voltage devices being one or more direct voltage converters (105-110, 205-210, 305-310) configured to transfer energy between the direct voltage bus and one or more charging supply devices (113, 135, 136, 213, 313) each having a vehicle coupling interface (114, 214, 314), and- an energy management system (117, 217, 317) configured to allocate power available at the direct voltage bus to the direct voltage devices in accordance with at least charging power demand or demands of one or more electric vehicles connected to the one or more charging supply devices,wherein the direct voltage bus comprises protector elements (118-122, 218-222, 242, 318-322, 342) each configured to break electric current through the protector element in response to violation of one or more protection attributes of the protector element, characterized in that the electric charging system comprises a protection control system (123, 223, 323) communicatively connected to the energy management system and to the protector elements, and configured to update at least part of the protection attributes of the protector elements in accordance with at least one of following: i) changes of allocation of the power available at the direct voltage bus to the direct voltage devices and ii) changes of electrical selectivity effecting characteristics of at least one part of the direct voltage bus.

2. An electric charging system according to claim 1 , wherein first ones (118-121 , 218-221 , 318-321 ) of the protector elements are located in front of the direct voltagedevices so that each of the first ones of the protector elements is configured to separate one or more of the direct voltage devices from the direct voltage bus in response to a situation in which behavior of at least one of following violates the protection attributes of the protector element: electric current through the protector element, direct voltage between current carrying poles of the protector element, and direct voltage between a current carrying pole of the protector element and ground.

3. An electric charging system according to claim 2, wherein the protection control system is configured to update an overcurrent trip limit of each of the first ones of the protector elements in accordance with the power allocated to the one or more direct voltage devices connected to the direct voltage bus via the protector element.

4. An electric charging system according to claim 2 or 3, wherein the protection control system is configured to update a time-current curve of each of the first ones of the protector elements in accordance with the power allocated to the one or more direct voltage devices connected to the direct voltage bus via the protector element.

5. An electric charging system according to any one of claims 1-4, wherein second one (122, 322, 324) or ones of the protector elements is / are located between parts (124, 125, 324, 325) of the direct voltage bus, and the second one or ones of the protector elements is / are configured to divide the direct voltage bus into electrically separate parts in response to a situation in which behavior of at least one of following violates the protection attributes of each of the second one or ones of the protector elements: electric current through the protector element, direct voltage between current carrying poles of the protector element, and direct voltage between a current carrying pole of the protector element and ground.

6. An electric charging system according to any one of claims 1 -5, wherein a first one or ones (105-107, 205-207, 305-307) of the direct voltage devices is / are connected to the direct voltage bus via one (118, 218, 318) of the protector elements and each of the first one or ones of the direct voltage devices is provided with an overcurrent protector (126) configured to disconnect the direct voltage device from the one of the protector elements in response to a situation in which temporalbehavior of electric current of the overcurrent protector exceeds a time-current curve of the overcurrent protector.

7. An electric charging system according to claim 6, wherein the overcurrent protector (126) is a fuse.

8. An electric charging system according to claim 6 or 7, wherein the electric charging system comprises an energy storage (127, 227, 327) connected to electric conductors from the one of the protector elements (118, 218, 318) to the first one or ones (105-107, 205-207, 305-307) of the direct voltage devices, and configured to supply electric current to a fault point within or after one of the first one or ones (105-107, 205-207, 305-307) of the direct voltage converters to cause the overcurrent protector of the one of the first one or ones of the direct voltage devices to separate the fault point from the one of the protector elements.

9. An electric charging system according to claim 8, wherein the energy storage comprises one or more capacitor elements.

10. An electric charging system according to any one of claims 1-9, wherein at least one (111 , 211 , 311 ) of the direct voltage devices comprises a battery energy storage (130) connected to the direct voltage bus via one (120) of the protector elements.

11. An electric charging system according to any one of claims 1-10, wherein at least one (112, 212, 312) of the direct voltage devices comprises a photovoltaic array (132) and a photovoltaic direct voltage converter (133) connected to the direct voltage bus via one (121) of the protector elements.

12. An electric charging system according to any one of claims 1-11, wherein the electric charging system comprises a switch array (134) between two or more of the direct voltage converters (105-107) and two or more of the charging supply devices (113, 135, 136), and a controller configured to control the switch array in accordance with the charging power demand or demands of the one or more electric vehicles connected to one or more of the charging supply devices connected to the switch array.

13. An electric charging system according to any one of claims 1-12, wherein the protector elements (118-122, 218-222, 242, 318-322, 342) are electronic circuit breakers.

14. A method for controlling an electric charging system that is suitable for charging electric vehicles, the electric charging system comprising:- a direct voltage bus (101, 201, 301),- one or more alternating voltage - direct voltage converters (102, 103, 202, 203, 302, 303) configured to transfer energy between an alternating voltage supply grid (104, 204, 304) and the direct voltage bus,- direct voltage devices (105-112, 205-212, 305-312) connected to the direct voltage bus, one or more of the direct voltage devices being one or more direct voltage converters (105-110, 205-210, 305-310) configured to transfer energy between the direct voltage bus and one or more charging supply devices (113, 135, 136, 213, 313) each having a vehicle coupling interface (114, 214, 314), and- an energy management system (117, 217, 317) configured to allocate power available at the direct voltage bus to the direct voltage devices in accordance with at least charging power demand or demands of one or more electric vehicles (115, 116, 215, 216, 315, 316) connected to the one or more charging supply devices,wherein the direct voltage bus comprises protector elements (118-122, 218-222, 242, 318-322, 342) each configured to break electric current through the protector element in response to violation of one or more protection attributes of the protector element, characterized in that the method comprises:- receiving (401) status data expressing at least one of following: i) allocation of the power available at the direct voltage bus to the direct voltage devices and ii) electrical selectivity effecting characteristics of at least one part of the direct voltage bus, and- updating (402) at least part of the protection attributes of the protector elements in accordance with at least one of following: i) changes of the allocation of the power available at the direct voltage bus to the direct voltage devices and ii) changes of the electrical selectivity effecting characteristics of the at least one part of the direct voltage bus.

15. A method according to claim 14, wherein first ones (118-121, 218-221, 318-321) of the protector elements are located in front of the direct voltage devices so that each of the first ones of the protector elements is configured to separate one or more of the direct voltage devices from the direct voltage bus in response to a situation in which behavior of at least one of following violates the protection attributes of the protector element: electric current through the protector element, direct voltage between current carrying poles of the protector element, and direct voltage between a current carrying pole of the protector element and ground.

16. A method according to claim 15, wherein the method comprises updating an overcurrent trip limit of each of the first ones of the protector elements in accordance with the power allocated to the one or more direct voltage devices connected to the direct voltage bus via the protector element.

17. A method according to claim 15 or 16, wherein the method comprises updating a time-current curve of each of the first ones of the protector elements in accordance with the power allocated to the one or more direct voltage devices connected to the direct voltage bus via the protector element.

18. A method according to any one of claims 14-17, wherein second one (122, 322, 324) or ones of the protector elements is / are located between parts (124, 125, 324, 325) of the direct voltage bus, and the second one or ones of the protector elements is / are configured to divide the direct voltage bus into electrically separate parts in response to a situation in which behavior of at least one of following violates the protection attributes of each of the second one or ones of the protector elements: electric current through the protector element, direct voltage between current carrying poles of the protector element, and direct voltage between a current carrying pole of the protector element and ground.

19. A method according to any one of claims 14-18, wherein first one or ones (105-107, 205-207, 305-307) of the direct voltage devices are connected to the direct voltage bus via one (118, 218, 318) of the protector elements and each of the first one or ones of the direct voltage devices is provided with an overcurrent protector (126) configured to disconnect the direct voltage devices from the one of the protector elements in response to a situation in which temporal behavior of electric current of the overcurrent protector exceeds a time-current curve of the overcurrent protector.

20. A method according to claim 19, wherein the overcurrent protector is a fuse.

21. A method according to claim 19 or 20, wherein the electric charging system comprises an energy storage (127, 227, 327) connected to electric conductors from the one of the protector elements to the first one or ones of the direct voltage devices, and the method comprises supplying electric current from the energy storage to a fault point within or after one of the first one or ones of the direct voltage devices to cause the overcurrent protector of the one of the first one or ones of the direct voltage devices to separate the fault point from the one of the protector elements.

22. A method according to claim 21 , wherein the energy storage comprises one or more capacitor elements.

23. A method according to any one of claims 14-22, wherein at least one (111, 211, 311) of the direct voltage devices comprises a battery energy storage (130) connected to the direct voltage bus via one (120) of the protector elements.

24. A method according to any one of claims 14-23, wherein at least one (112, 212, 312) of the direct voltage devices comprises a photovoltaic array (132) and a photovoltaic direct voltage converter (133) connected to the direct voltage bus via one (121) of the protector elements.

25. A method according to any one of claims 14-24, wherein the electric charging system comprises a switch array (134) between two or more of the direct voltage converters (105-107) and two or more of the charging supply devices (113, 135, 136), and the method comprises controlling the switch array in accordance with thecharging power demand or demands of the one or more electric vehicles (115) connected to one or more of the charging supply devices connected to the switch array.

26. A method according to any one of claims 14-25, wherein the protector elements (118-122, 218-222, 242, 318-322, 342) are electronic circuit breakers.

27. A computer program for controlling an electric charging system that is suitable for charging electric vehicles, the electric charging system comprising:- a direct voltage bus (101, 201, 301),- one or more alternating voltage - direct voltage converters (102, 103, 202, 203, 302, 303) configured to transfer energy between an alternating voltage supply grid (104, 204, 304) and the direct voltage bus,- direct voltage devices (105-112, 205-212, 305-312) connected to the direct voltage bus, one or more of the direct voltage devices being one or more direct voltage converters (105-110, 205-210, 305-310) configured to transfer energy between the direct voltage bus and one or more charging supply devices (113, 135, 136, 213, 313) each having a vehicle coupling interface (114, 214, 314), and- an energy management system (117, 217, 317) configured to allocate power available at the direct voltage bus to the direct voltage devices in accordance with at least charging power demand or demands of one or more electric vehicles connected to the one or more charging supply devices,wherein the direct voltage bus comprises protector elements (118-122, 218-222, 242, 318-322, 342) each configured to break electric current through the protector element in response to violation of one or more protection attributes of the protector element, characterized in that the computer program comprises computer executable instructions for controlling a programmable data processing system to:receive status data expressing at least one of following: i) allocation of the power available at the direct voltage bus to the direct voltage devices and ii) electricalselectivity effecting characteristics of at least one part of the direct voltage bus, and- update at least part of the protection attributes of the protector elements in accordance with at least one of following: i) changes of the allocation of the power available at the direct voltage bus to the direct voltage devices and ii) changes of the electrical selectivity effecting characteristics of the at least one part of the direct voltage bus.

28. A non-volatile computer readable medium encoded with a computer program according to claim 27.

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