ELECTRICAL SELF-CONSUMPTION SYSTEM OF AN INSTALLATION

Abstract

Electrical self-consumption system of an installation, comprising: a multistring photovoltaic inverter (6) configured to deliver alternating voltage to one or more loads (7) of an installation (8); a set of photovoltaic solar panels (5) connected in series to a first string (17) of the photovoltaic inverter (6); a hydrogen fuel cell (3); a DC / DC voltage converter (12) configured to convert the output voltage of the hydrogen fuel cell (3) to an operating voltage of a second string (18) of the photovoltaic inverter (6); and a control unit (20) configured to obtain, through a first power meter (11), the power delivered to the installation (8) and to activate, by controlling a switch or contactor (16), the output of the hydrogen fuel cell (3) when the power delivered to the installation (8) is below a certain threshold. The system allows the integration of photovoltaic self-consumption with a hydrogen fuel cell using a single inverter.

Description

ELECTRICAL SELF-CONSUMPTION SYSTEM OF AN INSTALLATION Field of invention The present invention falls within the electrical sector (renewable energies) and the hydrogen sector (energy). Background of the invention With respect to systems that integrate the power generation of a conventional photovoltaic generation system with a hydrogen fuel cell for the self-consumption of an installation, document CN113899074-A discloses a hybrid wind-solar system that supplies electricity to the home while storing excess energy as hydrogen through electrolysis, which is stored in a tank and used by a fuel cell system as a backup power source. Documents GB2581950A and CH704635-B1 disclose a system that includes solar panels, a hydrogen fuel cell, and a battery that stores the electrical energy generated by the fuel cell and solar panels, supplying power to devices on demand. The fuel cell activates when the battery charge falls below a certain level. However, in all prior art documents, the integration between photovoltaic self-consumption and hydrogen fuel cell generation is inefficient. The present invention solves this problem by providing an efficient integration of photovoltaic energy generation with hydrogen fuel cell energy generation. Description of the invention The invention relates to an electrical self-consumption system of an installation that allows a simple and efficient integration of the energy generation of a hydrogen fuel cell into an existing photovoltaic self-consumption system. The self-consumption electrical system of the present invention comprises a multi-string photovoltaic inverter configured to deliver alternating current to one or more loads of an installation. Photovoltaic solar panels are connected in series to a first string of the photovoltaic inverter, and a hydrogen fuel cell is connected to a second string of the photovoltaic inverter via a DC / DC voltage converter, which converts the output voltage of the hydrogen fuel cell to an operating voltage for said second string of the photovoltaic inverter. A control unit is configured to obtain, through a first power meter, the power delivered to the installation and to activate, by controlling a switch or contactor, the output of the hydrogen fuel cell when the power delivered to the installation is below a certain threshold. Since hydrogen fuel cells generate VDC voltage with different voltages depending on the hydrogen fuel cell plates, a specific inverter (VDC-VAC) is required for connection to the normal grid (e.g., 230-400VAC / 50HZ) to allow for grid injection or self-consumption. The present invention allows this injection or self-consumption to be managed by the multistring photovoltaic inverter that exists in any residential or industrial installation equipped with photovoltaic generation, this photovoltaic inverter being the one that manages all the photovoltaic self-consumption and of the hydrogen fuel cell with the dynamic power management (DLM, Dynamic Load Management) of the photovoltaic inverter itself, thus avoiding having to carry out the self-consumption with two redundant equipment (photovoltaic inverter and hydrogen fuel cell inverter). Therefore, the integration of both energy generation sources (photovoltaic and hydrogen fuel cell) of the installation is simplified since it is not necessary to use a second inverter, the hydrogen fuel cell inverter, with its corresponding DLM. Brief description of the drawings Next, a series of drawings are briefly described that help to better understand the invention and that are expressly related to an embodiment of said invention that is presented as a non-limiting example thereof. Figure 1 shows, as an example and schematically, the use of the system of the present invention for the self-consumption of electricity in an installation. Figure 2 shows an electrical self-consumption system of an installation according to a realization. Detailed description of the invention The hydrogen fuel cell system is a new technology for industrial and residential systems. Integrating energy generation with a hydrogen fuel cell through this solution simplifies its integration using a conventional photovoltaic installation. The photovoltaic inverter manages the energy for the self-consumption system, eliminating the need for redundant equipment such as a second inverter with its corresponding dynamic power management (DLM) system for the hydrogen fuel cell. Figure 1 represents the functional scheme of a hydrogen production facility 1 with metal hydride storage 2 that feeds a 2.5 KW hydrogen fuel cell 3 that generates energy and stores it in a first 48VDC battery 4 for use. The energy supply for this installation is 100% renewable, with solar production using a set of 5 photovoltaic solar panels connected in series (i.e., a string) to a photovoltaic inverter 6 responsible for transforming the direct current it receives from the photovoltaic panels into alternating current, which feeds a load 7 (or set of loads) of the installation 8 to which the inverter 6 is connected. All equipment is monitored and managed by a PLC 9 and supervised by an industrial SCADA system 10 which is responsible for representing all the elements with the operating strategy, starting and stopping equipment according to the operating parameters and activating the installed safety devices, among other control and monitoring actions. In a conventional photovoltaic solar installation with a multistring photovoltaic inverter 6 ("VDC STRING 1", "VDC STRING 2"), as shown in Figure 1, its normal operation is to generate energy during the day when there is solar radiation, allowing self-consumption of the installation 8 to which the photovoltaic inverter 6 is connected, and at night the photovoltaic inverter 6 remains on standby to receive voltage on the string ("VDC STRING 1") again to start working. In the present invention, the SCADA system 10 monitors the production delivered to the installation 8 (solar production when only the solar panels are activated) through a first power meter 11 and detects when solar production falls below a certain threshold at dusk or under cloudy conditions during the day.At that moment the SCADA system 10 starts the production of the hydrogen fuel cell 3, by activating a switch or contactor 16, energizing a dedicated string of the photovoltaic inverter 6 ("VDC STRING 2" in Figure 1), causing the photovoltaic inverter 6 to not stop and continue generating energy, allowing the self-consumption of the installation 8 also at night or on cloudy days when solar production needs additional power input, thus making a complete integration by only conditioning the string of the photovoltaic inverter 6 to the optimal operating voltage through a DC / DC voltage converter 12" (in the example of Figure 1, 48VDC / 380VDC converter). According to the embodiment shown in Figure 1, a second battery 13 (e.g., 5 kW) can be connected to the photovoltaic inverter 6 to reduce the operating time of the hydrogen fuel cell 3. The currents and voltages of each string of the photovoltaic inverter 6 where the photovoltaic system ("VDC STRING 1") and the hydrogen fuel cell-DC / DC voltage converter ("VDC STRING 2") are connected can also be monitored by means of a remote monitoring platform 14 provided by the inverter manufacturer, connected via the Internet 15. The photovoltaic inverter 6 is capable of extracting the maximum power from the hydrogen fuel cell 3 if the self-consumption of the installation 8 is high. Under these operating conditions, the photovoltaic inverter 6 connects to the grid, providing maximum backup power with the energy supplied by the array of photovoltaic panels 5, the second battery 13, and the hydrogen fuel cell 3, as long as the design power of the equipment is not exceeded. Figure 2 shows the elements that make up an electrical self-consumption system of an installation 8 according to one embodiment. The electrical self-consumption system comprises a multistring photovoltaic inverter 6 that receives direct current voltage from a plurality of input strings (17, 18, 19) and delivers alternating current voltage to one or more loads 7 of the installation 8. A set of photovoltaic solar panels 5 are connected in series to a first string 17 of the photovoltaic inverter 6. A hydrogen fuel cell 3 generates electrical energy from a hydrogen supply 22 and delivers it to a DC / DC voltage converter 12, which converts the output voltage of the hydrogen fuel cell 3 to an operating voltage of a second string 18 of the photovoltaic inverter 6. In one embodiment, the energy generated by the hydrogen fuel cell 3 can be stored in a first battery 4, which accumulates the generated energy when the switch or contactor 16 is deactivated. A control unit 20 (e.g., a PLC 9, a SCADA system 10, or a processor-based unit) is responsible for obtaining, via the first power meter 11, the power delivered to the installation 8 and activating, by controlling the switch or contactor 16, the output of the hydrogen fuel cell 3 when the power delivered to the installation 8 falls below a certain threshold. This threshold can be a predetermined value or determined based on the power demand of the installation 8 at any given time. For example, if the power delivered to the installation 8 is insufficient (less than the power demanded by the installation 8), the switch or contactor 16 is activated. This allows more power to reach the photovoltaic inverter 6 via the second string 18, originating from the hydrogen fuel cell 3, so that the photovoltaic inverter 6 is able to meet the demand of the installation 8.The control unit 20 can monitor the power delivered by the hydrogen fuel cell 3 through a second power meter 21. The use of a third string 19 of the photovoltaic inverter 6 can be considered to receive additional power from a second battery 13, to ensure that the power supplied to the installation 8 always covers the power demanded. Advantageously, with the system of the present invention, any electrical installation with a photovoltaic generation system and a photovoltaic inverter with more than one string could obtain additional electrical energy through a hydrogen fuel cell, allowing the self-consumption of electricity of an installation even under conditions of low (cloudy day) or zero (night) photovoltaic energy productivity, and without the need to use a second inverter for the hydrogen fuel cell.

Claims

1. An electrical self-consumption system for an installation, characterized in that it comprises: a multi-string photovoltaic inverter (6) configured to deliver alternating voltage to one or more loads (7) of an installation (8); a set of photovoltaic solar panels (5) connected in series to a first string (17) of the photovoltaic inverter (6); a hydrogen fuel cell (3); a DC / DC voltage converter (12) configured to convert the output voltage of the hydrogen fuel cell (3) to an operating voltage of a second string (18) of the photovoltaic inverter (6); and a control unit (20) configured to obtain, through a first power meter (11), the power delivered to the installation (8) and to activate, by controlling a switch or contactor (16), the output of the hydrogen fuel cell (3) when the power delivered to the installation (8) is below a certain threshold. 2.The system according to claim 1, characterized in that it comprises a first battery (4) configured to store energy generated by the hydrogen fuel cell (3).

3. The system according to any of the preceding claims, characterized in that it comprises a second battery (13) configured to provide energy to a third string (19) of the photovoltaic inverter (6).

4. The system according to any of the preceding claims, characterized in that the threshold is determined based on the power demanded by the installation (8).

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