METHOD FOR ENERGY SUPPLY IN A LOCAL ENERGY SUPPLY NETWORK

Description

[0001] The invention relates to a method for supplying energy in a local energy supply network, in particular after a power failure.

[0002] The increasing feed-in of electrical energy from renewable energy sources into the power grids poses major challenges for grid operators and energy suppliers, as the feed-in power and the available energy quantities from these energy sources, particularly from wind and solar power plants, are typically subject to temporal fluctuations. To compensate for these fluctuations, storage options must be provided that can store excess energy generated at one time and release it again at another time when needed. Due to the mostly decentralized energy feed-in and the fluctuations in the electrical energy fed in, grid stability can be compromised and the likelihood of power outages can increase.

[0003] More and more households have access to renewable energy sources, such as photovoltaic systems or small wind or hydropower plants, as well as corresponding electrical energy storage systems for storing (excess) electrical energy. In the event of a power outage, these households can supply themselves with the stored electrical energy. Households without energy storage systems, on the other hand, remain without energy supply during a power outage. It would therefore be desirable to be able to supply energy to households without energy storage systems in the event of a power outage.

[0004] State-of-the-art methods are known for restoring the power supply, at least locally, after a power outage. To prevent a (repeated) collapse of the established power supply, the power consumption and the required energy must not exceed the available power or the available energy.Marchgraber, Jürgen, and Wolfgang Gawlik. 2020. "Investigation of Black-Starting and Islanding Capabilities of a Battery Energy Storage System Supplying a Microgrid Consisting of Wind Turbines, Impedance- and Motor-Loads" Energies 13, no. 19: 5170. Published: October 5, 2020, describes a process in which the connection and disconnection of devices or consumers is based on electrical voltage and frequency. If, for example, the frequency drops, consumers are disconnected from the power grid by deactivating electrical switches. A drop in frequency is an indicator that the currently consumed energy or required power is greater than the available energy or power.

[0005] US 424,933 B2 discloses a method that connects or disconnects a subscriber's electrical loads depending on the available energy. The supply to other subscribers or households is not specified.

[0006] US 2022 / 0200336 A1 discloses a system and method for supplying energy to a microgrid in an isolated state. In the event of a fault, the microgrid is disconnected from a higher-level grid, and the supply to the participants is then regulated via an energy management system. Participants are connected to the microgrid via inverters, among others, which can feed electrical energy into the microgrid. A master is designated to feed the energy into the microgrid.

[0007] In light of these statements, it is the object of the present invention to mitigate or even completely avoid the disadvantages of the prior art. Preferably, the object of the present invention is to provide a method with which even subscribers of a local energy supply network that do not have their own energy storage can be supplied with electrical energy after a power outage.

[0008] This object is achieved by a method according to claim 1. Preferred embodiments are specified in the dependent claims.

[0009] According to the invention, a method for supplying energy in a local energy supply network, in particular after a power failure, is provided, wherein the local energy supply network can be connected to a higher-level energy supply network via a connection point and connects several subscribers, in particular households, to one another, wherein at least one of the subscribers has an energy supply device with an inverter for feeding into the local energy supply network and the method comprises the following steps: i) Isolating the local energy supply network from the higher-level energy supply network using an electrical switch in the connection point; ii) Isolating all subscribers from the local energy supply network using additional switches located at each subscriber; iii) Determining a master inverter and at least one slave inverter among the subscribers with an energy supply device if there are several subscribers, each with an energy supply device; otherwise, designating the inverter of the only subscriber with an energy supply device as the master inverter; iv) Connecting those subscribers that have energy supply devices to the local energy supply network via the respective additional switches, so that the master inverter and, if present, the at least one slave inverter can feed into the local energy supply network;v) Outputting an alternating voltage by the master inverter and, if present, the at least one slave inverter, wherein the frequency, voltage level and phase position of the alternating voltage are specified by the master inverter; vi) Determining the total energy available in the local energy supply network by the at least one energy supply device and / or the total electrical power available; vii) Connecting at least one subscriber without an energy supply device to the local energy supply network for feeding into the grid according to step v) depending at least on the total energy available, the total electrical power available, the expected consumption power of the at least one subscriber without an energy supply device and / or the expected energy requirement of the at least one subscriber without an energy supply device;viii) disconnecting subscribers, in particular subscribers without an energy supply facility, from the local energy supply network as needed, so that the stability of the local energy supply network is maintained;

[0010] With the method according to the invention, even subscribers without their own energy storage can be supplied with electrical energy in the event of a power failure in an energy supply network, in particular in the event of a power failure in a higher-level energy supply network. With the method according to the invention, subscribers are connected based at least on the total energy available, the total electrical power available, the expected consumption power of the subscribers and / or the expected energy demand of the subscribers. The total energy and the total electrical power available refer to the total energy available of the subscribers connected to the local energy supply network and the total electrical power available of the subscribers connected to the local energy supply network, respectively.Subscribers who would negatively impact grid stability due to excessively high expected energy demand or power consumption are not connected to the local energy supply grid, thus preventing a further collapse of the energy supply. In contrast to the state of the art, the connection and disconnection of subscribers from the local energy supply grid is therefore not based on the voltage curve and frequency. If the actual energy demand or power consumption of a subscriber is too high and would therefore place too great a load on the local energy supply grid, the subscriber is disconnected from the local energy supply grid or not connected at all. The local energy supply grid can, for example, be a low-voltage grid or part of a low-voltage grid.Low-voltage grids are typically operated with a line-to-line voltage (rms value) during normal operation. A low-voltage grid can be connected to a higher-level energy supply grid, for example a medium-voltage grid, via a connection point, for example a transformer. The connection point can be formed by a transformer or can have a transformer. A medium-voltage grid typically has a voltage of at least 1,000 V line-to-line voltage (rms value). A local energy supply grid can have a geographical extent of, for example, at least 100 m, at least 500 m, at least 1 km, at least 3 km or at least 5 km. For example, the geographical extent between the connection point and a subscriber can be at least 100 m, at least 500 m, at least 1 km, at least 3 km or at least 5 km.Several participants can be connected to the local energy supply network. The participants can represent organizationally separate units. Individual participants can, for example, be formed by a household or their own building. Each participant can have their own power connection point, in particular a building connection, for connection to the local energy supply network. At least one of the participants has an energy supply device, which can also have an energy generation device such as a photovoltaic system, a wind turbine, a hydroelectric power plant or another device for generating electrical energy. It is advantageous if the energy supply device has an electrical energy storage device for storing electrical energy, for example a home storage device. This allows surplus energy to be stored and released again at a later time.The energy supply device according to the invention further comprises an inverter that can convert direct current into alternating current. The inverter is designed, among other things, to feed into the local energy supply network. The method according to the invention provides the following steps, particularly in the event of a power failure in the higher-level energy supply network: In step i), the local energy supply network is disconnected from the higher-level energy supply network using one or more electrical switches. The switch(es) can have switching elements for each outer conductor of the local energy supply network. The electrical switch(es) can be arranged at the connection point or near the connection point, for example in a transformer building. The electrical switch(es) can be formed, for example, by isolating switches or load-break switches, etc.In step ii), all subscribers are disconnected from the local energy supply grid using additional switches located at each subscriber's location. These additional switches can each be integrated into a smart meter or controlled by a smart meter.

[0011] The additional switches can, for example, form a building connection for the participants. In step iii), a master inverter and at least one slave inverter are determined from among the participants with an energy supply device if there are multiple participants with an energy supply device; otherwise, the inverter of the only participant with an energy supply device is designated as the master inverter. Preferably, the inverter designated as the master inverter is the one belonging to the energy supply device with the most stored energy and / or the greatest available electrical power. Step iii) can also be performed before or during steps i) and ii). In particular, step iii) can already be performed during normal operation of the local energy supply grid, so that a master inverter is already determined in the event of a power failure.In step iv), those participants that have energy supply devices are connected to the local energy supply grid via the respective additional switches, enabling feeding into the local energy supply grid by the master inverter and, if present, the at least one slave inverter. In this case, it can be provided that only participants with high relevance are connected. Participants with low relevance can be disconnected from the energy supply grid or remain disconnected. Step iv) can, for example, also take place simultaneously with step v). The connection of the participants to energy supply devices can take place sequentially. In step v), an alternating voltage is output by the master inverter and, if present, by the at least one slave inverter, whereby the frequency, voltage level and phase position of the alternating voltage are specified by the master inverter.

[0012] As already mentioned, the connection of the participants with energy supply devices and thus the inverters can take place one after the other. The master inverter can specify a voltage level, in particular an amplitude, a frequency and a phase position of an alternating voltage for the at least one slave inverter, with which it is fed into the local energy supply grid. The at least one slave inverter adopts the specifications of the master inverter and feeds in an alternating voltage with the voltage level, the frequency and the phase position specified by the master inverter. The master inverter can therefore also be referred to as the lead. In one embodiment, the inverters can communicate with each other via a wireless or wired communication link.The communication connection between the inverters can be established, for example, via the outer conductors of the local power grid (powerline communication) or via a wireless or wired communication channel separate from the local power grid. In an alternative embodiment, the at least one slave inverter can measure the alternating voltage fed in by the master inverter and determine the voltage level, frequency, and phase position from this, whereupon the at least one slave inverter can also output an alternating voltage with the detected voltage level, frequency, and phase position. A separate data line is not required in this case. If the establishment of the power supply with the previously determined master inverter is unsuccessful, another inverter can be designated as the master inverter if multiple participants have power supply devices.By outputting the alternating voltage in step v) and connecting it in step iv), an island network is established that is operated by the participants with energy supply devices. In step vi), the total energy available in the local energy supply network by the at least one energy supply device and / or the total electrical power available by the at least one energy supply device is determined. Step vi) can also be performed simultaneously with or before the other steps i)-v). Step vi) can also be performed before a power outage, so that in the event of a power outage, information about the total power and / or the total available power is already available.The total available energy and the total available power can be determined by recording the electrical energy stored in the at least one energy supply device, in particular in an energy storage device of the energy supply device, by recording the energy or generating power currently generated by any energy generating device, and / or by forecasting the energy or generating power generated in the future by any energy generating device. The total available power can depend on the feed-in power of the energy supply device, in particular the inverter. The energy generated in the future by any energy generating device and the generating power can depend on the time of day, the season, and the weather and can preferably be based on statistical data.Time of day, season, and weather can therefore be taken into account when forecasting the total energy and total power. Preferably, after connecting those subscribers that have energy supply facilities, in step vii) the subscribers without an energy supply facility are connected to the local energy supply grid depending at least on the total energy available, the total electrical power available, the expected consumption of the subscribers, and / or the expected energy demand of the subscribers. This can prevent the local energy supply grid or the at least one energy supply facility from being placed under excessive strain. The expected consumption and the expected energy demand of a subscriber are the consumption and the energy demand that are assumed to be required after the respective subscriber is connected.The expected consumption and energy demand can be determined, for example, using statistical data from a past period or based on a subscriber's connected and activated electrical devices, such as refrigerators, lighting, heating systems, etc. For example, it can be determined that a subscriber's expected energy demand in the next 24 hours is 7 kWh, even if this was also the case on average over the past 7 days.

[0013] The expected consumption power can be determined by statistically recording the subscriber's consumption power. For example, the maximum or average consumption power of the last 24 hours can be used as the expected consumption power. For short-term periods, the expected consumption power is important for distributing the available energy. For long-term planning, the expected energy demand is primarily relevant. If the expected energy demand or the expected consumption power of a subscriber is too high, the subscriber will not be connected to the local energy supply grid. In step viii), subscribers are disconnected from the local energy supply grid as needed to maintain the grid stability of the local energy supply grid. The disconnection of subscribers occurs, for example, based on the actual consumption power and / or the actual energy demand of a subscriber.It can also be provided that subscribers are sorted by relevance, with subscribers of low relevance being disconnected from the power grid while subscribers of high relevance remain connected to the power grid. Preferably, subscribers without their own power supply device are disconnected from the local power grid first, before subscribers with power supply devices are disconnected from the local power grid. In other words, subscribers with power supply devices are given preferential priority. If the actual energy demand and / or actual power consumption of a subscriber is too high and would endanger the stability of the local power grid, the subscriber is disconnected from the local power grid by switching the corresponding additional switch.In one embodiment of the invention, it can be provided that predefined electrical consumers, such as kitchen appliances or outdoor lighting, are deactivated preferably automatically and in particular according to a predetermined sequence if the actual energy demand exceeds the expected energy demand and / or the actual consumption exceeds the expected consumption of a subscriber. The deactivation of the electrical consumers can be carried out using a smart home application. It can also be provided that subscribers without their own energy supply device are connected to the local energy supply network alternately, i.e. not simultaneously, preferably according to a predetermined sequence in order not to overload the local energy supply network. Steps i)-viii) can, but do not have to, be carried out in the specified order.The steps can, where technically possible, be performed simultaneously or at least partially or completely overlapping. Once the cause of the power outage has been remedied and the local power grid can be supplied with power again from the higher-level power grid, the master inverter and any slave inverters can be configured to stop feeding into the local power grid. The electrical switch at the connection point can then close again, so that the local power grid is again supplied with electrical power from the higher-level power grid. The other switches may also have been opened beforehand.

[0014] It is advantageous if, in step vii), the expected consumption power of the subscribers without an energy supply device is defined by a consumption power quota assigned to the subscriber, and the expected energy demand of the subscribers without an energy supply device is defined by an energy demand quota assigned to the subscriber. In one embodiment of the invention, the energy demand quota and / or the consumption power quota can be set manually by a user. In another embodiment, the assigned energy demand quota and / or the assigned consumption power quota can be set by an application based on the past energy and consumption power demand of a subscriber. The consumption power quota and the energy demand quota can therefore be determined using statistical methods.It is also possible for the total available electrical energy and the total available electrical power to be divided equally or taking the connected load into assigned energy demand quotas or consumption power quotas. In one embodiment of the invention, it can be provided that subscribers with an energy supply device also receive an assigned energy demand quota and an assigned consumption power quota. In one embodiment, all subscribers whose energy demand exceeds the energy demand quota and / or whose consumption power exceeds the consumption power quota can receive a request to reduce their energy demand and / or consumption power.

[0015] To prevent a disruption of the energy supply, participants without an energy supply facility with an actual energy demand / consumption that exceeds the allocated energy demand quota / consumption quota can be disconnected from the local energy supply grid in step viii). A participant's actual energy demand and consumption can be measured using measuring devices, particularly smart meters. This ensures security of supply and does not restrict the energy or available electrical power available to other participants.

[0016] In one embodiment of the invention, it can be provided that electrical consumers of the participants in the local energy supply network are categorized according to relevance and electrical consumers up to a certain relevance category are preferably deactivated automatically. In this way, the energy demand in the local energy supply network can be kept low in order to avoid the assigned energy demand quotas and consumption power quotas being exceeded. In one embodiment of the invention, it can also be provided that electrical consumers assigned to certain relevance categories are preferably deactivated automatically depending on the total energy available and / or the total power that can be called up. If the total energy available and / or the total power that can be called up is low, consumers in lower relevance categories are deactivated. If a lot of total energy ora high total available power is available, consumers in lower relevance categories can also be activated. The relevance categories are preferably ordered in ascending order according to their relevance. In an exemplary embodiment, electrical consumers such as refrigerators, heating systems and telecommunications devices can be assigned to a highest relevance category. Electrical consumers such as dishwashers, game consoles and water circulation pumps for swimming pools can be assigned to a lower relevance category. In one embodiment of the invention, depending on the assigned energy demand quota and / or the assigned consumption power quota of a subscriber, the electrical consumers can be activated or deactivated according to the level of the relevance category.If the assigned energy demand quota and / or the assigned consumption power quota are low, for example, only consumers in the highest relevance category can be activated. If the assigned energy demand quota and / or the assigned consumption power quota are sufficiently high, consumers in lower relevance categories can also be activated. Relevance categories can be defined, for example, if a subscriber has an emergency power circuit and a circuit for normal operation. The emergency power circuit would supply important consumers in the event of a power failure, thereby defining a high relevance category. The remaining consumers not supplied by the emergency power circuit belong to a lower relevance category. Switching to the emergency power circuit deactivates the consumers in the low relevance category and only supplies consumers in the high relevance category.However, it can also be provided that a participant has a smart home device that is connected to the loads and can activate or deactivate them depending on their relevance category. In another embodiment, the inverter can also activate or deactivate connected loads depending on their relevance category. In an alternative variant, a participant can be disconnected from the local energy supply grid if it cannot distinguish between loads in lower relevance categories and activate or deactivate them.

[0017] The connection point can be formed by a transformer or have a transformer that connects the local power supply network to the higher-level power supply network.

[0018] The local energy supply network can be formed by a low-voltage network and the higher-level energy supply network by a medium-voltage network.

[0019] It is preferred if the additional switches are each controlled by a smart meter or are each integrated into a smart meter. A smart meter is a device, in particular an electricity meter, that can receive and transmit data and is integrated into a communications network for remote transmission. Another term for smart meter is intelligent meter.

[0020] If multiple participants share a single energy supply, it is advantageous to designate the master inverter as the inverter assigned to the energy supply that, among all participants' energy supply devices, has the most currently available energy and / or the highest available electrical power at a given time. The determination time is preferably in step iii).

[0021] To exchange data, it is advantageous if a communication connection, preferably powerline communication, in particular powerline communication according to the HomePlug AV specification, IEEE 1901-2010 standard, or G.hn standard, exists between the master inverter, the switch, and the other switches. Furthermore, it is advantageous if at least one slave inverter can also communicate with the master inverter via the communication connection. As an alternative to powerline communication, Wi-Fi or LoRa-WAN can also be used.

[0022] In a preferred embodiment, the energy supply device comprises an electrical energy storage device and preferably an energy generation device, in particular a photovoltaic system or a wind turbine. The energy generation device can feed into the local energy supply grid directly or via the energy storage device with the aid of the inverter. A hydroelectric power plant can also be provided as the energy generation device.

[0023] The invention is described in more detail below with reference to figures, to which it is not intended to be limited.

[0024] They show: Fig. 1 a schematic representation of a local energy supply network; Fig. 2 a flowchart; and Fig. 3 another flowchart.

[0025] Fig. 1 shows a local energy supply network 1 in the form of a low-voltage network 2, which is connected via a connection point 3 to a higher-level energy supply network 4 in the form of a medium-voltage network 5. The low-voltage network 2 is designed as a TN system (French: Terre Neutre) and electrically connects several subscribers 6a, 6b. Each subscriber 6a, 6b has its own building 7. In the illustration shown, each subscriber represents a separate household. The connection point 3 has a transformer 8 in a transformer station 8a, which transforms the higher voltage of the medium-voltage network 5 (over 1000 V line-to-line voltage) into the lower voltage of the low-voltage network 2 (400 V line-to-line voltage). Among the subscribers 6a, 6b, there are subscribers 6a with their own energy supply device 9 and subscribers 6b without their own energy supply device 9.An energy supply device 9 each has at least one inverter 10a, 10b for feeding into the local energy supply network 1 and preferably also an energy storage device 11 and / or an energy generation device 12. An energy generation device 12 can, for example, have a photovoltaic system 13, a wind turbine, or a hydroelectric power plant (not shown). The local energy supply network 1 is connected to the higher-level energy supply network 4 via at least one switch 14 and can be disconnected from it using the switch 14. The switch 14 can have a separate switching element for each outer conductor. The switch 14 can be arranged in or on the transformer 8. Each subscriber 6a, 6b is connected to the local energy supply network 1 via a further switch 15. The further switches 15 can also each have switching elements for each outer conductor.The additional switches can each be integrated into a smart meter 16 or controlled by a smart meter 16. The additional switches 15 can connect the subscribers 6a, 6b to or disconnect them from the local energy supply network 1. Each subscriber 6a, 6b has at least one consumer 17, which is connected to the local energy supply network 1. Fig. 1 illustrated by a circuit diagram of a light. Consumers 17 can also be, for example, refrigerators or electronic devices such as televisions and radios.

[0026] The inverters 10a, 10b, the switch 14, and the additional switches 15 can communicate with each other via a wireless or wired communication connection 50. In particular, a powerline communication 51 can be provided. The inverters 10a, 10b, the switch 14, and the additional switches 15 can communicate with each other via the outer conductors of the local power grid 1 and exchange data or commands.

[0027] During normal operation, participants 6a whose energy supply devices 9 have energy generation devices 12 can feed excess electrical energy into the local energy supply grid 1 via the inverters 10a, 10b. Even in this state, one of the inverters 10a, 10b can be designated as the master inverter 10a (see step iii) below). The other inverters 10a, 10b represent slave inverters 10b. Participants 6b without an energy supply device 9 draw electrical energy from the local energy supply grid 1. Using the smart meters 16, the actual energy demand E and the actual consumption P of each participant 6a, 6b can be statistically recorded and stored over time.By statistically recording the energy demand E and the consumption power P of the participants 6a, 6b, statistical forecasts can be made about the expected energy demand EE and the expected consumption power PE of each participant 6a, 6b.

[0028] In the event of a power failure 18, for example in the higher-level energy supply network 4, the subscribers 6a, 6b can no longer obtain electrical energy from the higher-level energy supply network 4. In order to nevertheless ensure the energy supply in the local energy supply network, the invention provides a method for energy supply, which in a preferred embodiment comprises the steps described below (see also Fig. 2 ). The steps can, but do not have to, be performed in the order given. Some steps can also be performed at least partially or completely overlapping.

[0029] Initially, normal operation 19 will take place (see Fig. 2 ), in which energy is supplied from the higher-level energy supply network 4 to the participants 6a, 6b. The actual energy demand E and the actual consumption P of the participants 6a, 6b can be measured using the smart meters 16. During normal operation 19, a master inverter 10a can already be determined (see explanations for step iii) below), as is illustrated by the designation of the first block with iii). In the event of a power failure 18, all inverters 10a, 10b can be automatically deactivated.

[0030] In step i), the switch 14 can electrically disconnect the local power grid 1 from the higher-level power grid 4. This can occur automatically if a power failure 18 occurs. However, the switch 14 can also be switched manually, for example, during maintenance work, to disconnect the local power grid 1 from the higher-level power grid 4.

[0031] In a step ii), all participants 6a, 6b are separated from the local energy supply network 1 by the further switches 15.

[0032] In a step iii) (as already mentioned above in connection with normal operation), a master inverter 10a is determined. The remaining inverters 10b represent slave inverters 10b. The master inverter 10a can, as explained, already be determined during normal operation 19 of the local energy supply grid, i.e., before a power outage 18 occurs. An inverter 10a, 10b can be manually selected as the master inverter 10a. It is preferred if the inverter 10a, 10b belonging to the energy supply device 9 with the highest available energy E a and / or the highest available electrical power P a is determined as the master inverter 10a.In the embodiment shown, the energy supply device 9 with the highest available energy E a and / or the highest available electrical power P a is the one with an energy storage device 11 with the largest amount of stored electrical energy ES . If grid setup is not possible with the specific master inverter 10a, a new master inverter 10a is determined, as illustrated by line 21.

[0033] In step iv), those participants 6a which have a power supply device 9 are connected to the local power supply network 1 via the respective further switches 15, so that a feed-in of the master inverter 10a and the slave inverters 10b into the local power supply network 1 is enabled.

[0034] In step v), an alternating voltage U is output by the master inverter 10a and the slave inverters 10b, wherein the frequency f, voltage level A and phase position φ of the alternating voltage U are specified by the master inverter 10a. The frequency f, voltage level A and phase position φ can be communicated to the slave inverters 10b via the communication link 50, in particular the powerline communication 51. The slave inverters 10b output an alternating voltage U whose frequency f, voltage level A and phase position φ correspond to the specifications of the master inverter 10a. The slave inverters 10b can be switched on one after the other in order to check whether they are supplied with an alternating voltage that has the specified frequency f, the specified voltage level A and the specified phase position φ.This creates an island network that can supply the participants 6a, 6b independently of the higher-level energy supply network 4, even those without their own energy supply facility 9.

[0035] In step vi), the total electrical energy E total available by the energy supply device 9 in the local energy supply network 1 and the total electrical power P total available are determined. This step can also be carried out, for example, simultaneously with steps i)-v) or already during normal operation 19. The total available energy E total and the total electrical power P total available can be determined by recording the electrical energy ES stored in the energy storage devices 10 of the energy supply device 9, by recording the energy or generating power currently generated by any energy generating device 12 and / or by forecasting the energy or generating power generated in the future by any energy generating device 12.

[0036] In step vii), the subscribers 6b without an energy supply device 9 are connected to the local energy supply network 1 depending on the total energy available E total, the total electrical power available P total, the expected consumption power PE of the subscribers 6b and / or the expected energy demand EE of the subscribers 6b. The expected consumption power PE and the expected energy demand EE of a subscriber 6b are the consumption power and the energy demand that are assumed to be required after the respective subscriber 6b is connected. The expected consumption power PE and the expected energy demand EE can, for example, be determined using statistical data from a past period or on the basis of the connected and activated electrical consumers 17 of a subscriber 6b, such as refrigerators, lighting, heating devices, etc.

[0037] In an energy supply network 1, only as much energy can be consumed as is available. The total actual consumption power P of all subscribers 6a, 6b must not exceed the total available power P total. To comply with these specifications, the expected consumption power PE of subscribers 6b without an energy supply device 9 is defined by a consumption power quota KP assigned to subscriber 6b, and the expected energy demand of subscribers 6b without an energy supply device 9 is defined by an energy demand quota KE assigned to subscriber 6b. A consumption power quota KP and an energy demand quota KE can also be assigned to subscribers 6a with their own energy supply device 9.

[0038] If an actual energy demand E or an actual consumption P of a subscriber 6b without an energy supply facility 9 exceeds the respectively assigned energy demand quota KE or the respectively assigned consumption quota KP, the subscriber 6b can be requested to reduce its actual energy demand E or its actual consumption P. If the subscriber 6b fails to comply, step viii) can provide for the disconnection of subscribers 6b without their own energy supply facility 9 from the local energy supply network 1. It can also be provided for the prioritization of subscribers 6a with energy supply facilities 9.If a subscriber 6a with energy supply device 9 exceeds its energy demand quota KE or its consumption power quota KP, it can also be provided that a subscriber 6b without its own energy supply device 9 is disconnected from the local energy supply network 1 in order not to endanger the network stability.

[0039] Fig. 3 shows the process of Fig. 2 in more detail. In normal operation 19, a master inverter 10a is determined, and the actual consumption power P and the actual energy demand E of the participants 6a, 6b are statistically recorded. The energy ES contained in the energy storage devices 11 and the generating power are also recorded (block 101).

[0040] In block 102, a power failure 18 occurs. In block 103, all inverters 10a and 10b are deactivated. In block 104, the source of the fault is determined. If it is not in the local power grid 1, the process continues.

[0041] In block 105, switch 14 at connection point 3 and the other switches 15 at participants 6a, 6b are opened.

[0042] In block 106, the additional switch 15 assigned to subscriber 6a, which is assigned to the master inverter 10a, is closed. The master inverter 10a then feeds an alternating voltage U with a frequency f, a voltage level A, and a phase angle φ into the local energy supply grid 1 and starts island operation. If the grid setup fails, a new master inverter 10a is determined (block 107). If this also fails, the process is aborted (block 108). In block 109, the additional switches 14 of the other subscribers 6a with inverter 10a are connected to the local energy supply grid 1. The subscribers 6b without their own energy supply device 9 are also connected in block 109, preferably after the subscribers 6a with energy supply device 9 have been connected.The connection of participants 6b is based on their assigned energy demand quotas KE and consumption power quotas KP, so that grid stability is maintained. If the actual energy demand E and the actual consumption power P of a participant 6a, 6b exceeds the assigned energy demand quota KE or the assigned consumption power quota KP, the participant 6a, 6b can be disconnected from the local energy supply grid 1, preferably after a request, by opening the respective additional switch 15, in order to stabilize the grid (block 110).In this case, a prioritization of the participants 6a with energy supply device 9 can also be carried out by removing a participant 6b without its own energy supply device 9 from the local energy supply network if the assigned energy demand quota or the assigned consumption power quota of a participant 6a with energy supply device is exceeded.

[0043] In block 111, the resolution of power outage 18 is reported to the master inverter 10a. In block 112, all inverters 10a and 10b cease operation. In block 113, all other switches 15 are opened. In block 114, switch 14 is closed. In block 115, the other switches 15 are closed, preferably one after the other.

Claims

1. Method for supplying energy in a local energy supply network (1), in particular after a power outage (18), wherein the local energy supply network (1) can be connected to a higher-level energy supply network (4) via a connection point (3) and connects a plurality of participants (6a, 6b), in particular households, wherein at least one of the participants (6a) comprises an energy supply device (9) with an inverter (10a, 10b) for feeding into the local energy supply network (1) and the method comprises the following steps: i) Disconnecting the local energy supply network (1) from the higher-level energy supply network (4) using an electrical switch (14); ii) Disconnecting all participants (6a, 6b) from the local energy supply network (1) with the help of further switches (15), which are located at the participants (6a, 6b); iii) Determining a master inverter (10a) and at least one slave inverter (10b) among the participants (6a) with an energy supply device (9) if there are several participants (6a) with an energy supply device (9); otherwise, determining the inverter (10a) of the only participant (6a) with an energy supply device (9) as the master inverter (10a); iv) Connecting those participants (6a) comprising energy supply devices (9) to the local energy supply network (1) via the respective further switches (15), so that the master inverter (10a) and, if present, the at least one slave inverter (10b) can feed into the local energy supply network (1); v) output of an alternating voltage (U) by the master inverter (10a) and, if present, the at least one slave inverter (10b), the frequency (f), voltage amplitude (A) and phase angle (φ) of the alternating voltage (U) being predetermined by the master inverter (10a); vi) determining the total electrical energy (Eges) and / or the total electrical power (Pges) available in the local energy supply network (1) provided by the at least one energy supply device (9); vii) connecting at least one participant (6b) without an energy supply device (9) to the local energy supply network (1) after step v) as a function of at least the total energy (Eges) available, the total electrical power (Pges) available, the expected power consumption (PE) of the at least one participant (6b) without an energy supply device (9) and / or the expected energy demand (Ee) of the at least one participant (6b) without an energy supply device (9); viii) Disconnecting participants (6a, 6b), in particular participants (6b) without an energy supply device (9), from the local energy supply network (1) as required, so that the grid stability of the local energy supply network (1) is maintained.

2. Method according to claim 1, wherein in step vii) the expected power consumption (PE) of the participants (6b) without energy supply device (9) is defined in each case by a power consumption quota (KP) assigned to the participant (6b) and the expected energy demand (Ee) of the participants (6b) without energy supply device (9) is defined in each case by an energy demand quota (KE) assigned to the participant (6b).

3. Method according to claim 2, wherein participants (6b) without an energy supply device (9) with an actual energy demand (E) / actual power consumption (P) which is higher than the respective energy demand quota (KE) / respective power consumption quota (KP), are disconnected from the local energy supply network (1) in step viii).

4. Method according to one of claims 1 to 3, wherein electrical consumers (17) of the participants (6a, 6b) on the local energy supply network (1) are categorized according to relevance and electrical consumers (17) are preferably automatically deactivated up to a certain relevance category.

5. Method according to one of claims 1 to 4, wherein the connection point (3) is formed by a transformer (8) or comprises a transformer (8) which connects the local energy supply network (1) to the higher-level energy supply network (4)6. Method according to one of claims 1 to 5, wherein the local energy supply network (1) is a low voltage network (2) and the higher-level energy supply network (4) is a medium voltage network (5).

7. Method according to any one of claims 1 to 6, wherein the further switches (15) are each controlled by a smart meter (16) or are each integrated in smart meters (16).

8. Method according to one of claims 1 to 7, wherein, if several participants (6a) with an energy supply device (9) are present, that inverter (10a) is determined as master inverter (10a) which is assigned to that energy supply device (9) which comprises the most currently available energy (Ea) and / or provides the highest retrievable electrical power (Pa) among all the energy supply devices (9) of the participants (6a) at a determination time.

9. Method according to one of claims 1 to 8, wherein a communication connection (50), preferably a powerline communication (51), is present between the master inverter (10a), the switch (14) and the further switches (15).

10. Method according to one of claims 1 to 9, wherein the energy supply device (1) comprises an electrical energy storage device (11) and preferably an energy generation device (12), in particular a photovoltaic system (13) or a wind turbine.