Device for managing the power supply to a local grid

Abstract

The invention relates to a power supply management device (1) comprising: - a grid input (3); - a first power supply interface (5) for powering critical loads of a local grid; - an islanding switch (7); - a central controller (10); - a grid-forming inverter (14) configured to provide an uninterruptible power supply to the critical loads; - at least one battery (11); and - at least one bidirectional charging terminal (12) for an electric vehicle (13) such that the home battery (11) can be used to charge the electric vehicle (13) and, when an electric vehicle (13) is plugged in and has enough charge, such that a battery of the electric vehicle can be used to charge the home battery (11); such that the power supply management device can operate in an islanding mode in which the home battery (11) and / or the battery of the electric vehicle (13) power the power supply interface (5).

Description

Local area network power management device

[0001] The present invention relates to the management of the power supply of a local electrical network, in particular for a dwelling.

[0002] The invention finds a particularly advantageous application for optimizing the use of a home battery and an electric vehicle battery, both when the local network is supplied by the distribution network (off-grid mode), and when the local network is supplied by one or both of the aforementioned batteries (on-grid mode).

[0003] With rising energy costs and growing concerns about the environmental impact of traditional energy sources, it is becoming imperative to develop efficient and sustainable solutions for managing the power supply of local consumer electricity networks.

[0004] These solutions are advantageously compatible with domestic energy production methods, such as photovoltaic panels, and allow for the best use of available storage capacities such as domestic batteries, and batteries of electric vehicles connected to the local network via a charging station.

[0005] These solutions sometimes include an "off-grid" or islanding mode, allowing the local network to be powered without using the external distribution network.

[0006] Document US11011913 proposes such a system, enabling an islanding mode in which the local grid is powered by an electric vehicle battery and / or a home battery. This system has the disadvantage of being complex, requiring a large number of components, and causing a temporary interruption of power to the local grid when islanding is triggered.

[0007] The technical problem of the invention is therefore to propose a power management system for a local network which allows for the optimized and economically efficient use, in "on-grid" and "off-grid" mode, of the energy stored in a home battery and in an electric vehicle, the system being arranged in an original way in order to reduce the number of components required and to allow for uninterrupted power supply to the local network.

[0008] The present invention aims to address this technical problem by proposing a local network power management device integrating: - a network input, configured to be connected to a public electricity network; - a first interface for supplying critical loads of the local network; - an islanding switch, the first terminal of which is connected to the network input; - a first voltage sensor, disposed between the network input and the islanding switch; - a central controller, configured to receive the measurements from said first voltage sensor and open the islanding switch when the measured voltage is below an islanding threshold for a first predetermined duration;- a network forming inverter, said network forming inverter comprising a first AC terminal connected to the second terminal of said islanding switch, a DC terminal, and a backup AC terminal connected to the first power interface, said network forming inverter being configured to provide, at the backup AC terminal, an uninterruptible supply to the critical loads of the local network independently of any disturbances on the public electricity network;- at least one domestic battery connected to the DC terminal of the grid shaping inverter, said domestic battery having a power rating strictly less than 50 kW and being capable of: supplying at least the critical loads of the local network, for a second predetermined duration longer than the first predetermined duration, and feeding electricity back into the public grid; - at least one bidirectional electric vehicle charging station connected to the first AC terminal of the grid shaping inverter, so that the domestic battery can be used to charge the electric vehicle and, when an electric vehicle is plugged in with sufficient charge, that a battery of the electric vehicle can be used to charge the domestic battery;the power management device capable of operating in an islanding mode in which the home battery and / or the electric vehicle battery power the power interface.

[0009] The invention thus optimizes battery usage since, in normal operating mode, the home battery can be used to supplement the power supplied to the grid input to power the charging station and enable rapid charging of the electric vehicle. Furthermore, critical loads benefit from an uninterrupted power supply regardless of any disruptions on the public electricity grid.

[0010] Furthermore, in islanding mode, the home battery can be supplemented by the electric vehicle's battery to ensure the longest possible local grid supply. In this islanding mode, the electric vehicle can be disconnected, and only the home battery then supplies the local grid. Moreover, by regularly charging the electric vehicle at fast charging stations, it is even possible to recharge the home battery and supply the local grid using the electric vehicle's battery, thus theoretically guaranteeing a local grid supply for an unlimited duration, provided that the electric vehicle's battery capacity is sufficient to meet the local grid's consumption.

[0011] Between normal operating mode and islanding mode, the grid-forming inverter ensures uninterrupted power supply to critical local network loads. This uninterruptible power supply is preferably also used to power certain components of the power management device of the invention, including the central controller, the auxiliary components of the home battery, and the islanding switch.

[0012] The quality of the electrical signal on an islanded network, particularly its harmonic distortion, is generally lower than on a non-islanded network and, depending on the sensitivity of the electrical components on the islanded network, may require the use of costly filtering systems. Thanks to its uninterruptible power supply (UPS) function, the grid shaping inverter can filter the electrical signal entering the local network and guarantee its quality even in islanded conditions.

[0013] In addition to normal and islanding modes, a preferred embodiment of the invention also allows the batteries to be used to implement a balancing mode. In this embodiment, the way the central controller manages the power management device depends on how the home battery and / or the electric vehicle battery are used. More specifically, in this mode, the central controller is configured to be able to control the power management device of a local grid in a balancing mode where the islanding switch is closed and the home battery and / or the electric vehicle battery are used to inject or draw power from the grid input.In the first operating mode, corresponding to the first type of balancing, the central controller is connected to a device that measures the characteristics of the electrical signal from the grid, specifically its voltage and frequency. In the second operating mode, corresponding to the second type of balancing, the central controller communicates with the grid operator via a communication network. It then controls the balancing mode based on instructions sent by the grid operator.

[0014] Another operating mode uses the home and / or electric vehicle batteries to optimize the local grid power supply when the islanding switch is closed. In this embodiment, the central controller is typically connected to a communication network and / or the installation's meter to command the local grid power management device to charge and discharge the batteries at the appropriate times. For example, the grid power management device can be commanded to: - charge the batteries when grid electricity is inexpensive, without exceeding the maximum permissible contracted power on the local grid; and - use the batteries to supply the local grid when grid electricity is expensive.

[0015] In the case of a domestic installation, the local grid's needs can sometimes exceed the power that the grid can deliver, causing power outages or limitations. This can occur, in particular, if the electrical power subscribed to by the consumer and measured at the installation's meter is temporarily lower than the power drawn, or more generally if the characteristics of the local grid connection do not allow the local grid to draw all the power it needs, at least temporarily.

[0016] To address this type of situation, the central controller can be configured to receive a measurement of the electrical signal power at the grid input and to control the management device in an overload absorption mode. In this mode, when the power supplied by the grid is less than the local grid's needs, the home battery and / or the electric vehicle battery are used to supplement the local grid. When the central controller detects an overload situation—that is, a situation where the local grid's consumption exceeds a set or measured threshold—it controls the grid shaping inverter to inject the necessary power into the local grid to absorb the overload. This energy is drawn from the home battery and / or the electric vehicle battery.

[0017] Thanks to these provisions, the device according to the invention allows optimal use of electrical energy resources from the network, stored in the home battery and in the electric vehicle battery, in "on-grid" mode as well as in "off-grid" mode.

[0018] The network connected to the network input may be a low-voltage network, but the network input may incorporate protection and transformation devices to connect a high-voltage or medium-voltage network, depending on the local network to be protected. In the case of a low-voltage network, the local network typically corresponds to a domestic network.

[0019] At least one of the loads enabling the repowering of the local network in the event of an outage, among the central controller, and the auxiliaries of the home battery and / or the charging station, can be connected to the backup AC terminal of the network forming inverter, so as not to use an uninterruptible power supply for at least one of these loads.

[0020] The central controller can be configured to close a neutral-to-ground switch, thereby connecting the neutral of the second terminal of the islanding switch to ground when the islanding switch is open. This automatically performs the grounding and ensures the safety of the local network. In a particular embodiment of the invention, this neutral-to-ground switch can be directly integrated into the device.

[0021] The first predetermined duration can be less than 10 seconds, which is sufficient time to start the "off-grid" mode, and more specifically the supply of the local network via the home battery and / or the electric vehicle battery.

[0022] The power of the domestic battery is strictly less than 50 kW, for example between 5 and 20 kW, which is a power particularly suited to a conventional domestic network.

[0023] The said management device may include an interface to a photovoltaic installation, said interface being connected to the DC terminal of the grid forming inverter, which allows optimal use of the energy produced by the photovoltaic installation in combination with the energy stored in the home battery, in the electric vehicle battery, and with the energy from the public grid.

[0024] The management system may include a second interface for supplying non-critical local grid loads, connected to the second terminal of the islanding switch, and the central controller is configured so that, in the event of the islanding switch opening, it commands the grid shaping inverter to supply the non-critical local grid loads via the first AC terminal of the grid shaping inverter. Thus, all loads are supplied in "off-grid" mode, but only the critical loads receive uninterruptible power.This allows the permissible electrical power on the backup AC terminal of the network formation inverter to be optimally sized, the interruption of the supply of certain loads for a duration of, for example, 1 second is not detrimental, while allowing the entire local network to be supplied when the islanding mode is properly activated.

[0025] The present invention also relates to a method of using a management device according to the invention, comprising the following steps: - supplying critical loads of the local network from the public electricity network; - measurement by the first voltage sensor of a voltage below said islanding threshold, indicating disturbances on the public electricity network, leading to the activation of the uninterruptible power supply function of the network formation inverter, in order to avoid an interruption in the supply of critical loads; - measurement by the first voltage sensor of a voltage below said islanding threshold for a first predetermined period; - opening of the islanding switch, and switching of the network formation inverter from a network following mode to a network formation mode;- regulation of the voltage on the local network by the network forming inverter, using measurements from a second voltage sensor located at the second terminal of the islanding switch, - measurement by the first voltage sensor of a voltage exceeding a connection threshold for a third predetermined duration, resulting in the closure of the islanding switch, - supply of critical loads of the local network by the public electricity network.

[0026] This process may also include, just before the islanding switch closing step, a step of synchronizing the voltage and / or frequency of the network inverter to the voltage and / or frequency of the public electricity network.

[0027] This process may include, after the islanding switch opening step, a step of supplying non-critical loads from the local network by the home battery, via the network forming inverter.

[0028] The present invention and its advantages will become more apparent from the following description of several embodiments given by way of non-limiting examples, with reference to the accompanying drawings, in which:

[0029] This is a schematic view of a management device according to a preferred embodiment of the invention.

[0030] With reference to the diagram, the power management device for a local network 1 according to the invention is connected to a public network 2 via an input 3, preferably located downstream of the connection of an electricity meter 4. The public network 2 may be a low-voltage network, supplying, for example, to the device 1 a single-phase or three-phase alternating voltage of 230 or 400 V, at a power of, for example, approximately 12 kVA. The public network 2 may also be a medium- or high-voltage network.

[0031] Device 1 includes a first interface 5a for supplying critical loads from the local network, which is configured to be connected to the local network's electrical panel 6. Device 1 may also include a second interface 5b for supplying non-critical loads from the local network, which is configured to be connected to the local network's electrical panel 6. The first interface 5a, and optionally the second interface 5b, is preferably configured to be the sole source of power to the electrical panel 6. The electrical panel 6 is preferably a "TGBT" type panel, for "General Low Voltage Panel". In another embodiment of the invention, it may also be a low-voltage sub-panel, positioned downstream of a "TGBT".

[0032] Device 1 also includes an islanding switch 7, preferably mechanized, of which a first terminal 7a is connected to the input 3, and a first voltage sensor 8, disposed between the islanding switch 7 and the input 3.

[0033] Device 1 also includes a central controller 10. The central controller 10 is configured to receive measurements from the first voltage sensor 8, via known wired or wireless communication means, and to control the opening and closing of the islanding switch 7. When a failure of the public network 2 is detected, for example via a voltage value below an islanding threshold for a first predetermined period, the central controller 10 commands the opening of the islanding switch 7, in order to switch Device 1 to "off-grid" mode.

[0034] To analyze the current state from the public grid 2 in greater detail, the first voltage sensor 8 can be a combined voltage and current and / or frequency sensor. This allows the central controller 10 to operate the device 1 in a grid balancing mode, in "on-grid" mode, and to make more informed decisions regarding whether or not to switch the device to "off-grid" mode. The monitoring of the public grid 2 can be carried out as described in French patent FR 3128167.

[0035] Device 1 further includes a grid formation inverter 14. The grid formation inverter 14 is a bidirectional AC / DC inverter, which includes a first AC terminal AC1, connected to the second terminal 7b of the islanding switch 7, a DC terminal, and a backup AC terminal AC2 connected to the first power interface 5a. The grid formation inverter 14 includes a converter capable of synchronizing its frequency and voltage with that of the public electricity grid, in a "grid following" mode, and delivering a voltage and frequency for a local network in a "grid formation" mode. The grid formation inverter 14 can therefore be used to restore a network during a total power outage of the public grid 2, in a so-called "black start" configuration.

[0036] Furthermore, the network forming inverter 14 is configured to operate as an uninterruptible power supply (UPS). The network forming inverter 14 provides continuity of service at its AC2 backup terminal to prevent interruptions in the power supply to critical local network loads.

[0037] To perform these functions, the network forming inverter 14 communicates with the central controller 10 via known wired or wireless communication methods.

[0038] The device preferably includes a second voltage sensor 20, which may be a combined voltage and current and / or frequency sensor, located at the second terminal 7b of the islanding switch 7. The second voltage sensor 20 is in communication with the central controller 10, which transmits information from the second sensor 20 to the network shaping inverter 14, so that the network shaping inverter 14 can regulate the voltage and frequency of the local network in "off-grid" mode.

[0039] The uninterruptible power supply (UPS) function is present in the grid-forming inverter by means of a specific system that provides such power. This type of system is known and commercially available.

[0040] Publication EP3681008 A1 provides an example of such a system for supplying stable electrical power to a load, even during a fault in the commercial power grid. This system, without its "distributed energy resources" component, which in the present invention consists of elements described separately from the grid-forming inverter 14 (see below), can be directly integrated into the grid-forming inverter 14 to provide it with an uninterruptible power supply function.

[0041] Publication EP4254721 A1 gives another example of an uninterruptible power supply system, which can be integrated into the network forming inverter 14 to give it the uninterruptible power supply function.

[0042] In "off-grid" mode, the local network, composed of at least 5a critical loads, is supplied by local energy storage means, and possibly by local energy production means.

[0043] To do this, the device 1 includes at least one domestic battery 11, connected to the DC direct current terminal of the grid forming inverter 14, and at least one bidirectional charging terminal 12 for an electric vehicle 13, connected to the first AC1 alternating current terminal of the grid forming inverter 14.

[0044] The domestic battery 11 is sized to be able to supply critical loads on the local network, via the network shaping inverter 14 operating in "UPS" mode, for a second predetermined period, longer than the first predetermined period. The first predetermined period is, for example, less than 10 seconds.

[0045] For example, the domestic battery 11 has a power output between 5 and 20 kW, and a capacity between 5 and 50 kWh.

[0046] The central controller 10 is preferably electrically connected to the grid shaping inverter 14, on its second AC2 terminal. This allows the grid shaping inverter 14 to be configured to provide uninterrupted power to the central controller 10 for a predetermined period. This ensures that in the event of a grid failure, the power supply to the central controller 10 is not interrupted, and thus the grid shaping inverter 14 can effectively control the local grid supply when device 1 switches to "off-grid" mode.

[0047] In addition to the central controller 10, the home battery auxiliaries 11, such as ventilation, cooling or other systems, can be connected in the same way to the grid forming inverter 14, which allows the home battery 11 to be operational when the device 1 switches to "off-grid" mode.

[0048] Similarly, the charging station controller 12 and possibly other charging station auxiliaries 12 can be connected in the same way to the grid forming inverter 14, which allows the electric vehicle battery 13 to be operational to supply the local grid via the charging station 12 when the device 1 is switched to "off-grid" mode.

[0049] The auxiliaries of the domestic battery 11 and the charging station 12 are represented by the reference sign “18” on the.

[0050] The central controller 10 can be configured to control a neutral-earth switch 19, preferably mechanized, located at the second terminal 7b of the islanding switch 7. When the device 1 is put into "off-grid" mode, particularly by opening the islanding switch 7, the neutral of the electrical panel 6, according to the local network earthing scheme 1, may no longer be connected to earth. The central controller 10 can then command the closing of the neutral-earth switch 19, in order to ground the neutral of the electrical panel 6.

[0051] The invention optimizes the use of energy available in the home battery 11 and the electric vehicle battery 13. The central controller 10 can be connected, via wired or wireless communication, to the battery controller (or battery "EMS," for "energy management system") and to the charging station 12 to perform this optimization. Thus, in "off-grid" mode, the central controller 10 can take into account the charge level of these batteries and their respective draw-off capacity in order to intelligently utilize the energy they contain.

[0052] Specific configurations can be imposed on the central controller 10. For example, it can be instructed to ensure that the battery of the electric vehicle 13 is fully charged every day at a certain time, or to maintain a constant charge at all times to allow for an unexpected departure at any moment. In "off-grid" mode, it may be preferable to keep the battery of the electric vehicle 13 fully or partially charged, allowing the vehicle to travel to recharge its battery outside of device 1 and thus return energy to device 1. This ensures continued power to the local grid in the event of a prolonged outage, without being limited by the energy present in the home battery 11 and the electric vehicle battery at the time of the outage.

[0053] The central controller 10 can be in communication with a third voltage and / or current sensor located at the electrical panel 6, in order to take into account the instantaneous consumption of the local network in the management of device 1.

[0054] Device 1 may include an interface 15 to a photovoltaic system 16, connected to the grid-forming inverter 14 at its DC terminal. Thus, the photovoltaic system 16 can be used to charge the home battery 11, the electric vehicle battery 13, or to supply the local grid. One or more of these services can be provided by the system simultaneously. The central controller 10, which is then in communication with the photovoltaic system 16, is configured to take into account the amount of energy produced at any given time by the photovoltaic system 16, in order to determine the optimal way to use it.

[0055] In another embodiment of the invention, the photovoltaic installation 16 can be directly integrated into the device. It can be connected to the grid-forming inverter 14 via a DC-DC converter, allowing adjustment of the current and voltage downstream of the grid-forming inverter.

[0056] The central controller 10 can be connected to a communication network 17, in order to allow remote management and / or monitoring of device 1. Remote management makes it possible in particular to synchronize the management of a plurality of devices 1, or to take into account in the management of device 1 the state of other elements connected to the public network 2. In addition, remote communication makes it possible to predict production by retrieving, for example, weather forecasts.

[0057] The device according to the invention can be used in a process comprising the following steps: - supplying critical loads of the local network from the public electricity grid; - measuring, by the first voltage sensor 8, a voltage below the islanding threshold, indicating disturbances on the public electricity grid. If the first voltage sensor 8 is also a frequency sensor, measuring a frequency outside a predefined range can also trigger the continuation of this step.From the first occurrence of such a measurement, the central controller 10 sends information to the network formation inverter 14 so that the network formation inverter 14 activates its function of uninterrupted supply of critical loads; - measurement by the first voltage sensor 8 of a voltage below the islanding threshold, or possibly of a frequency outside a predefined range, for a first predetermined duration; - opening of the islanding switch 7, controlled by the central controller 10, and switching of the network formation inverter 14 from "network following" mode to "network formation" mode.On this occasion, critical loads remain powered without interruption, or with a very short interruption, considered negligible within the scope of the present invention, for example, on the order of 20 ms; - regulation of the voltage, and possibly the frequency, on the local network by the grid forming inverter 14, using measurements from a second voltage and possibly frequency sensor 20 located at the second terminal 7b of the islanding switch 7; - measurement by the first voltage sensor of a voltage exceeding a connection threshold for a third predetermined duration, indicating that the disturbances on the public electricity network have ended. This measurement triggers the closure of the islanding switch 7, controlled by the central controller 10.Prior to this shutdown, the grid inverter 14 can operate a "synchrocoupling" with the public electricity grid, i.e., a synchronization of the voltage and / or frequency delivered by the grid inverter 14 with the voltage and / or frequency of the public electricity grid. This is achieved using measurements from the first voltage sensor and, optionally, the frequency sensor 8. The advantage of "synchrocoupling" is that the switchover from the power supply of the training inverter 14 to the public grid is transparent to the loads—the critical loads of the local grid are supplied by the public electricity grid, thus the device 1 switches to "off-grid" mode.

[0058] When the local network also includes non-critical loads, connected to a second power interface 5b, the above process may include, after opening the islanding switch 7, a step of supplying the non-critical loads from the home battery and / or the electric vehicle battery 13.

[0059] The invention allows, when the device 1 is in "on-grid" mode, to manage the consumption of the site, for example by recharging the domestic battery 11 and / or that of the electric vehicle during off-peak hours, and to discharge these batteries to absorb peak consumption during peak hours.

[0060] Device 1 according to the invention also allows for fast charging of the electric vehicle 13, since the energy required for charging can be directly drawn from the home battery 11, at a higher instantaneous power than that delivered by the public network 2 alone.

[0061] The present invention is not limited to the embodiments described but extends to any modification and variant obvious to a person skilled in the art, within the limits of the appended claims. Furthermore, the technical features of the various embodiments and variants mentioned above may be combined, in whole or in part.

Claims

Local area network power management device (1) integrating: - a network input (3), configured to be connected to a public electricity network; - a first power interface (5a) for critical loads of the local area network; - an islanding switch (7) of which a first terminal (7a) is connected to the network input (3); - a first voltage sensor (8), disposed between the network input (3) and the islanding switch (7); - a central controller (10), configured to receive the measurements of said first voltage sensor (8) and open the islanding switch (7) when the measured voltage is below an islanding threshold for a first predetermined duration;- a network forming inverter (14), said network forming inverter (14) comprising a first AC terminal (AC1) connected to the second terminal (7b) of said islanding switch, a DC terminal, and a backup AC terminal (AC2) connected to the first power interface (5a), said network forming inverter (14) being configured to provide, at the backup AC terminal (AC2), an uninterruptible supply to the critical loads of the local network;- at least one domestic battery (11) connected to the DC terminal of the grid shaping inverter (14), said domestic battery (11) having a power rating strictly less than 50 kW and being capable of: supplying at least the critical loads of the local network, for a second predetermined duration greater than the first predetermined duration, and feeding electricity back onto the grid input (3) for the public grid; - at least one bidirectional charging station (12) for an electric vehicle (13) connected to the first AC terminal (AC1) of the grid shaping inverter (14), so that the domestic battery (11) can be used to charge the electric vehicle (13) and, when an electric vehicle (13) is plugged in with sufficient charge, that a battery of the electric vehicle can be used to charge the domestic battery (11);the power management device capable of operating in an islanding mode in which the home battery (11) and / or the electric vehicle battery (13) supply the power interface (5). Management device (1) according to claim 1, characterized in that the central controller (10) is configured to be able to control the power management device of a local network (1) in a balancing mode in which the islanding switch (7) is closed and the home battery (11) and / or the electric vehicle battery (13) are used to perform injection or withdrawal on the network input (3). Management device (1) according to any one of claims 1 or 2, characterized in that the central controller (10) is configured to receive a measurement of the power of the electrical signal measured at the network input (3), and to be able to control the management device (1) in an overload absorption mode in which, when the power delivered by the network is less than the needs of the local network, the home battery (11) and / or the battery of the electric vehicle (13) are used to supply the local network in addition to the public network. Management device (1) according to any one of claims 1 to 3, characterized in that at least one of the loads enabling the re-powering of the local network in the event of a power outage, among the central controller (10), and the auxiliaries (18) of the home battery (11) and / or the charging station (12), is connected to the backup AC power station (AC2), so as not to use an uninterruptible power supply for at least one of these loads. Management device (1) according to any one of claims 1 to 4, characterized in that the central controller (10) is configured to close at least one earth-neutral switch (19) allowing the neutral of the second terminal (7b) of the islanding switch (7) to be connected to earth when the islanding switch (7) is open. Management device (1) according to any one of claims 1 to 5, characterized in that the first predetermined duration is less than 10 seconds. Management device (1) according to any one of claims 1 to 6, characterized in that the power of the domestic battery (11) is between 5 and 20 kW. Management device (1) according to any one of claims 1 to 7, characterized in that it comprises an interface (15) to a photovoltaic installation (16), said interface (15) being connected to the direct current (DC) terminal of the grid forming inverter (14). A management device (1) according to any one of claims 1 to 8, characterized in that it comprises a second local non-critical load supply interface (5b) connected to the second terminal (7b) of the islanding switch (7), and in that the central controller (10) is configured so that in the event of opening of the islanding switch (7), the central controller (10) commands the network forming inverter (14) to supply the local non-critical loads via the first AC terminal (AC1) of the network forming inverter (14). A method of using a management device according to any one of claims 1 to 9, comprising the following steps: - supplying the critical loads of the local network from the public electricity network; - measurement by the first voltage sensor (8) of a voltage below said islanding threshold, indicating disturbances on the public electricity network, leading to the activation of the uninterruptible power supply function of the network formation inverter, in order to avoid an interruption in the supply of the critical loads; - measurement by the first voltage sensor (8) of a voltage below said islanding threshold for a first predetermined period; - opening of the islanding switch (7), and switching of the network formation inverter (14) from a network following mode to a network formation mode;- regulation of the voltage on the local network by the network forming inverter (14), using the measurements of a second voltage sensor (20) located at the second terminal (7b) of the islanding switch (7),- measurement by the first voltage sensor of a voltage above a connection threshold for a third predetermined duration, resulting in the closure of the islanding switch (7),- supply of critical loads of the local network by the public electricity network.; A method of use according to claim 10, further comprising, just before the step of closing the islanding switch (7), a step of synchronizing the voltage and / or frequency of the network inverter (14) to the voltage and / or frequency of the public electricity network. Method of using according to any one of claims 10 to 11 a management device according to claim 9, comprising after the step of opening the islanding switch (7) a step of supplying the non-critical loads of the local network by the domestic battery (11), via the network forming inverter (14).

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