A microgrid system of liquid flow battery and hydrogen energy storage and its working method

Abstract

The present invention discloses a microgrid system of liquid flow battery and hydrogen energy storage and a working method thereof. The power station is respectively connected to the power grid, a DC / AC converter and an electrolyzer. The DC / AC converter is respectively connected to the positive electrode in the positive electrolyte cavity and the negative electrode in the negative electrolyte cavity. The top outlet of the positive electrolyte cavity is connected to the inlet of the positive electrode storage tank, and the outlet of the positive electrode storage tank is connected to the bottom inlet of the positive electrolyte cavity via a first circulation pump; the top outlet of the negative electrode electrolyte cavity is connected to the inlet of the negative electrode storage tank, and the outlet of the negative electrode storage tank is connected to the bottom inlet of the negative electrode electrolyte cavity via a second circulation pump. The system and the working method thereof can realize peak and frequency regulation of the microgrid and realize multi-energy complementarity.

Description

Technical Field

[0001] The present invention belongs to the field of integrated energy storage power stations and relates to a microgrid system of liquid flow batteries and hydrogen energy storage and a working method thereof. Background Art

[0002] With the further prosperity of my country's economic market, the scale of my country's power generation and electricity consumption will continue to maintain a growth trend in the future. In the power generation and electricity consumption model with multi-energy complementarity and source-grid-load coordination, as the proportion of new energy power generation gradually increases, the energy storage system will gradually assume the role of peak-shaving and frequency regulation, accident standby, and load standby in the regional power grid.

[0003] With the vigorous development of the energy storage industry, various energy storage methods have enabled the phased storage of electricity, solving the problem of asynchronous power generation from renewable energy sources and post-grid consumption. However, these various energy storage methods currently have their own problems. Current energy storage methods include pumped hydro, compressed air, flywheel, superconducting, electrochemical, hydrogen, and phase change thermal storage. The main energy storage methods that can be used on a large scale for grid peak and frequency regulation are pumped hydro, electrochemical, and hydrogen. Pumped hydro offers the best economic benefits over longer periods of time, but cannot absorb excessive net power from the grid. Electrochemical storage is the most convenient to use, but is not suitable for peak and frequency regulation with large-scale grids. Hydrogen storage has a broad market, but the system struggles to operate sustainably. Therefore, there is an urgent need to develop new, sustainable energy storage systems to achieve peak and frequency regulation in microgrids and multi-energy complementarity. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a microgrid system of liquid flow batteries and hydrogen energy storage and its working method, which can realize peak and frequency regulation of the microgrid and achieve multi-energy complementarity.

[0005] To achieve the above objectives, the liquid flow battery and hydrogen energy storage microgrid system of the present invention includes a power station, a power grid, a liquid flow battery energy storage system and a hydrogen energy storage system, wherein the liquid flow battery energy storage system includes a DC / AC converter, a positive electrode electrolyte chamber, a positive electrode storage tank, a first circulation pump, a second circulation pump, a negative electrode electrolyte chamber and a negative electrode storage tank; the hydrogen energy storage system includes an electrolyzer;

[0006] The power station is connected to the power grid, the DC / AC converter and the electrolyzer respectively. The DC / AC converter is connected to the positive electrode in the positive electrolyte chamber and the negative electrode in the negative electrolyte chamber respectively. The top outlet of the positive electrolyte chamber is connected to the inlet of the positive electrode storage tank, and the outlet of the positive electrode storage tank is connected to the bottom inlet of the positive electrode electrolyte chamber via a first circulation pump; the top outlet of the negative electrode electrolyte chamber is connected to the inlet of the negative electrode storage tank, and the outlet of the negative electrode storage tank is connected to the bottom inlet of the negative electrode electrolyte chamber via a second circulation pump.

[0007] The hydrogen outlet of the electrolyzer is connected to the inlet of the hydrogen storage device, and the oxygen outlet of the electrolyzer is connected to the inlet of the oxygen storage device.

[0008] The outlet of the hydrogen storage device is connected to the inlet of the hydrogen utilization unit, and the outlet of the oxygen storage device is connected to the oxygen utilization unit.

[0009] The working method of the microgrid system of liquid flow battery and hydrogen energy storage of the present invention includes a microgrid energy storage stage and a microgrid power generation stage.

[0010] In the microgrid energy storage stage, after all the electricity generated by the power station is connected to the grid, the excess electricity will be stored first through the liquid flow battery energy storage system, and secondly through the hydrogen energy storage system.

[0011] Set Q p is the real-time power generation of the power station, Q g is the real-time output power of the power grid, C full To determine whether the flow battery energy storage system is fully charged, C lower To determine whether the storage capacity of the flow battery energy storage system is less than the lower limit, Q b,in is the input power of the flow battery energy storage system, Q H,min The minimum power consumption of the hydrogen energy storage system is divided into three sub-operating conditions in the microgrid energy storage stage, specifically:

[0012] Under the first sub-condition, Q p ≥Q g And C full is true, under this condition, Q p =Q g +Q H , the flow battery energy storage system does not work, Q p Middle Q g of the electricity is transferred to the grid, and the remaining Q H The electricity is transmitted to the hydrogen energy storage system to make the electrolyzer work;

[0013] Under the second sub-condition, Q p ≥Q g And C full is false and C lower is false. Under this condition, Q p =Q g +Q H,min +Q b,in , the hydrogen energy storage system is the lowest capacity, Q p Middle Q g The amount of electricity is transferred to the grid, and Q H,min of electricity is transferred to the hydrogen energy storage system to make it work, and the remaining Q b,inThe electricity is transmitted to the liquid flow battery energy storage system to make the DC / AC converter work, and the DC / AC converter drives the liquid flow battery energy storage system to charge. The electrolyte in the positive electrode storage tank is sent to the positive electrode electrolyte cavity through the first circulation pump, and the electrolyte in the negative electrode storage tank is sent to the negative electrode electrolyte cavity through the second circulation pump;

[0014] Under the third sub-condition, Q p ≥Q g And C lower is true, under this condition, Q p =Q g +Q b,in , the hydrogen energy storage system does not work, Q p Middle Q g of the electricity is transferred to the grid, and the remaining Q b,in The electricity is transmitted to the flow battery energy storage system for storage.

[0015] During the microgrid power generation stage, even after all the electricity generated by the power station is connected to the grid, it still cannot meet the power demand of the grid. At the same time, the liquid flow battery energy storage system is used to generate electricity to supplement the power demand of the grid.

[0016] Set Q p is the real-time power generation of the power station, Q g is the real-time output power of the power grid, C lower To determine whether the storage capacity of the flow battery energy storage system is less than the lower limit, Q b,out is the output power of the flow battery energy storage system, Q H is the real-time power consumption of the hydrogen energy storage system, Q H,min The minimum power consumption of the hydrogen energy storage system is divided into two sub-operating conditions during the microgrid power generation phase, specifically:

[0017] Under the first sub-condition, Q p <Q g And C lower is false. Under this condition, Q g +Q H,min =Q p +Q b,out , the hydrogen energy storage system is the lowest capacity, Q p All the electricity is connected to the grid, and the flow battery energy storage system generates Q b,out Of the electricity, part of Q H,min The electricity is transferred to the hydrogen energy storage system to make it work, and the remaining Q b,out -Q H,min of electricity is transmitted to the grid;

[0018] Under the second sub-condition, Q p <Q g And C lower is true, under this condition, Qg =Q p +Q b,out , the hydrogen energy storage system does not work, Q p The amount of electricity is transmitted to the grid, and Q b,out of electricity is transmitted to the grid.

[0019] The present invention has the following beneficial effects:

[0020] During specific operation of the liquid flow battery and hydrogen energy storage microgrid system and its working method described in the present invention, the liquid flow battery energy storage system is used to store electricity and realize functions such as grid peak and frequency regulation. The system's net power generation is ultimately converted into hydrogen energy and consumed by the market. During the system's power generation or energy storage process, the hydrogen energy storage system continues to operate. The two subsystems are coupled to compensate for the shortcomings of each subsystem operating alone. Therefore, the present invention combines new energy power generation with grid dispatching to gradually and completely replace the traditional thermal power peak and frequency regulation, accident standby, and load standby functions, while providing the market with stable hydrogen energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Among them, 1 is a power station, 2 is a power grid, 3 is a liquid flow battery energy storage system, 3-1 is a DC / AC converter, 3-2 is a positive electrode electrolyte cavity, 3-3 is a positive electrode storage tank, 3-4-1 is a first circulation pump, 3-4-2 is a second circulation pump, 3-5 is a negative electrode electrolyte cavity, 3-6 is a negative electrode storage tank, 4 is a hydrogen energy storage system, 4-1 is an electrolyzer, 4-2 is a hydrogen storage device, 4-3 is a hydrogen utilization unit, 4-4 is an oxygen storage device, and 4-5 is an oxygen utilization unit. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0024] The accompanying drawings illustrate schematic diagrams of the structures of the disclosed embodiments of the present invention. These figures are not drawn to scale; for the purpose of clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0025] refer to Figure 1 The liquid flow battery and hydrogen energy storage microgrid system of the present invention includes a power station 1, a power grid 2, a liquid flow battery energy storage system 3 and a hydrogen energy storage system 4, wherein the liquid flow battery energy storage system 3 includes a DC / AC converter 3-1, a positive electrode electrolyte chamber 3-2, a positive electrode storage tank 3-3, a first circulation pump 3-4-1, a second circulation pump 3-4-2, a negative electrode electrolyte chamber 3-5 and a negative electrode storage tank 3-6; the hydrogen energy storage system 4 includes an electrolyzer 4-1, a hydrogen storage device 4-2, a hydrogen utilization unit 4-3, an oxygen storage device 4-4 and an oxygen utilization unit 4-5;

[0026] The power station 1 is connected to the power grid 2, the DC / AC converter 3-1 and the electrolytic cell 4-1 respectively. The DC / AC converter 3-1 is connected to the positive electrode in the positive electrolyte chamber 3-2 and the negative electrode in the negative electrolyte chamber 3-5 respectively. The top outlet of the positive electrolyte chamber 3-2 is connected to the inlet of the positive electrode storage tank 3-3. The outlet of the positive electrode storage tank 3-3 is connected to the bottom inlet of the positive electrolyte chamber 3-2 through the first circulation pump 3-4-1; the outlet of the negative electrolyte chamber 3-5 is connected to the bottom inlet of the positive electrolyte chamber 3-2. The top outlet is connected to the inlet of the negative electrode liquid storage tank 3-6, and the outlet of the negative electrode liquid storage tank 3-6 is connected to the bottom inlet of the negative electrode electrolyte chamber 3-5 through the second circulation pump 3-4-2; the hydrogen outlet of the electrolyzer 4-1 is connected to the inlet of the hydrogen storage device 4-2, the oxygen outlet of the electrolyzer 4-1 is connected to the inlet of the oxygen storage device 4-4, the outlet of the hydrogen storage device 4-2 is connected to the inlet of the hydrogen utilization unit 4-3, and the outlet of the oxygen storage device 4-4 is connected to the oxygen utilization unit 4-5.

[0027] The net power generation of the grid 2 in the microgrid system of liquid flow batteries and hydrogen energy storage described in the present invention is positive.

[0028] Set Q p is the real-time power generation of power station 1, Q g is the real-time output power of grid 2, C full To determine whether the flow battery energy storage system 3 is fully charged, C lower To determine whether the storage capacity of the flow battery energy storage system 3 is less than the lower limit, Q b,in is the input power of the flow battery energy storage system 3, Q b,outis the output power of the flow battery energy storage system 3, Q H is the real-time power consumption of the hydrogen energy storage system 4, Q H,min It is the minimum power consumption of hydrogen energy storage system 4.

[0029] refer to Figure 1 The microgrid power dispatching method of the liquid flow battery + hydrogen energy storage of the present invention includes two operating conditions. The first operating condition is: the microgrid energy storage stage, and the second operating condition is: the microgrid power generation stage;

[0030] Under the first operating condition, after all the electricity generated by power station 1 is connected to the grid, grid 2 cannot absorb all the electricity. Power station 1 transmits the excess electricity to the energy storage station, where electricity is stored first through the liquid flow battery energy storage system 3, and hydrogen is stored secondly through the hydrogen energy storage system 4. This operating condition is divided into three sub-operating conditions, among which,

[0031] Under the first sub-condition, Q p ≥Q g And C full is true, under this condition, Q p =Q g +Q H , the flow battery energy storage system 3 does not work, and Q p Middle Q g of the electricity is transferred to the grid 2, and the remaining Q H The electricity is transmitted to the hydrogen energy storage system 4, which enables the electrolyzer 4-1 to operate. The hydrogen produced by the electrolyzer 4-1 is stored in the hydrogen storage device 4-2. The hydrogen in the hydrogen storage device 4-2 is further consumed by the hydrogen utilization unit 4-3. The oxygen produced by the electrolyzer 4-1 is stored in the oxygen storage device 4-4. The oxygen in the oxygen storage device 4-4 is further consumed by the oxygen utilization unit 4-5.

[0032] Under the second sub-condition, Q p ≥Q g And C full is false and C lower is false. Under this condition, Q p =Q g +Q H,min +Q b,in , hydrogen energy storage system 4 is the lowest capacity, Q p Middle Q g The amount of electricity is transmitted to the grid 2, and Q H,min The electricity is transferred to the hydrogen energy storage system 4 to make it work, and the remaining Q b,inThe electricity is transmitted to the liquid flow battery energy storage system 3 to make the DC / AC converter 3-1 work, and the DC / AC converter 3-1 drives the liquid flow battery energy storage system 3 to charge. The electrolyte in the positive electrode storage tank 3-3 is sent to the positive electrode electrolyte cavity 3-2 through the first circulation pump 3-4-1, and the electrolyte in the negative electrode storage tank 3-6 is sent to the negative electrode electrolyte cavity 3-5 through the second circulation pump 3-4-2;

[0033] Under the third sub-condition, Q p ≥Q g And C lower is true, under this condition, Q p =Q g +Q b,in , the hydrogen energy storage system 4 does not work, Q p Middle Q g of the electricity is transferred to the grid 2, and the remaining Q b,in The electricity is transmitted to the liquid flow battery energy storage system 3 for storage.

[0034] Under the second operating condition, after all the power generated by power station 1 is connected to the grid, it cannot meet the power demand of grid 2. The energy storage system needs to supplement the power to be connected to the grid. The second operating condition is divided into two sub-conditions:

[0035] Under the first sub-condition, Q p <Q g And C lower is false. Under this condition, Q g +Q H,min =Q p +Q b,out , hydrogen energy storage system 4 is the lowest capacity, Q p All the electricity is connected to the grid, and the liquid flow battery energy storage system 3 works to generate Q b,out Of the electricity, part of Q H,min The electricity is transmitted to the hydrogen energy storage system 4 to make it work, and the remaining Q b,out -Q H,min The amount of electricity is transmitted to the grid 2;

[0036] Under the second sub-condition, Q p <Q g And C lower is true, under this condition, Q g =Q p +Q b,out , the hydrogen energy storage system 4 does not work, Q p The amount of electricity is transmitted to the grid 2, and Q b,out The amount of electricity is transmitted to the grid 2.

[0037] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for operating a microgrid system of liquid flow battery and hydrogen energy storage, characterized in that: It includes the microgrid energy storage stage and the microgrid power generation stage; Set Q p is the real-time power generation of power station (1), Q g is the real-time output power of the power grid (2), C full To determine whether the flow battery energy storage system (3) is fully charged, C lower To determine whether the storage capacity of the flow battery energy storage system (3) is less than the lower limit, Q b,in is the input power of the flow battery energy storage system (3), Q H,min The minimum power consumption of the hydrogen energy storage system (4) is divided into three sub-operating conditions in the microgrid energy storage stage, specifically: Under the first sub-condition, Q p ≥Q g And C full is true, under this condition, Q p =Q g +Q H , the flow battery energy storage system (3) does not work, and Q p Middle Q g of the electricity is transferred to the grid (2), and the remaining Q H The electricity is transmitted to the hydrogen energy storage system (4) to enable the electrolyzer (4-1) to work; Under the second sub-condition, Q p ≥Q g And C full is false and C lower is false. Under this condition, Q p =Q g +Q H,min +Q b,in , the hydrogen energy storage system (4) is the lowest capacity, Q p Middle Q g The amount of electricity is transferred to the grid (2), and Q H,min The electricity is transferred to the hydrogen energy storage system (4) to make it work, and the remaining Q b,in The electricity is transmitted to the liquid flow battery energy storage system (3) to make the DC / AC converter (3-1) work, and the DC / AC converter (3-1) drives the liquid flow battery energy storage system (3) to charge, and the electrolyte in the positive electrode storage tank (3-3) is sent to the positive electrode electrolyte cavity (3-2) through the first circulation pump (3-4-1), and the electrolyte in the negative electrode storage tank (3-6) is sent to the negative electrode electrolyte cavity (3-5) through the second circulation pump (3-4-2); Under the third sub-condition, Q p ≥Q g And C lower is true, under this condition, Q p =Q g +Q b,in , the hydrogen energy storage system (4) does not work, Q p Middle Q g of the electricity is transferred to the grid (2), and the remaining Q b,in The electricity is transmitted to the flow battery energy storage system (3) for storage; In the microgrid power generation stage, after all the electricity generated by the power station (1) is connected to the grid, it still cannot meet the electricity demand of the grid (2). At the same time, the liquid flow battery energy storage system (3) generates electricity to supplement the electricity demand of the grid (2); Set Q p is the real-time power generation of power station (1), Q g is the real-time output power of the power grid (2), C lower To determine whether the storage capacity of the flow battery energy storage system (3) is less than the lower limit, Q b,out is the output power of the flow battery energy storage system (3), Q H is the real-time power consumption of the hydrogen energy storage system (4), Q H,min is the minimum power consumption of the hydrogen energy storage system (4), which is divided into two sub-operating conditions in the microgrid power generation stage, specifically: Under the first sub-condition, Q p <Q g And C lower is false. Under this condition, Q g +Q H,min =Q p +Q b,out , the hydrogen energy storage system (4) is the lowest capacity, Q p All the electricity is connected to the grid, and the flow battery energy storage system (3) generates Q b,out Of the electricity, part of Q H,min The electricity is transferred to the hydrogen energy storage system (4) to make it work, and the remaining Q b,out -Q H,min of electricity is transmitted to the grid (2); Under the second sub-condition, Q p <Q g And C lower is true, under this condition, Q g =Q p +Q b,out , the hydrogen energy storage system (4) does not work, Q p The amount of electricity is transferred to the grid (2), and Q b,out The amount of electricity is transferred to the grid (2).

2. The operating method of the microgrid system of liquid flow battery and hydrogen energy storage according to claim 1, characterized in that: The invention comprises a power station (1), a power grid (2), a liquid flow battery energy storage system (3) and a hydrogen energy storage system (4), wherein the liquid flow battery energy storage system (3) comprises a DC / AC converter (3-1), a positive electrode electrolyte chamber (3-2), a positive electrode storage tank (3-3), a first circulation pump (3-4-1), a second circulation pump (3-4-2), a negative electrode electrolyte chamber (3-5) and a negative electrode storage tank (3-6); the hydrogen energy storage system (4) comprises an electrolyzer (4-1); The power station (1) is connected to the power grid (2), the DC / AC converter (3-1) and the electrolytic cell (4-1) respectively. The DC / AC converter (3-1) is connected to the positive electrode in the positive electrolyte chamber (3-2) and the negative electrode in the negative electrolyte chamber (3-5) respectively. The top outlet of the positive electrolyte chamber (3-2) is connected to the inlet of the positive electrode storage tank (3-3). The outlet of the positive electrode storage tank (3-3) is connected to the bottom inlet of the positive electrode electrolyte chamber (3-2) via a first circulation pump (3-4-1); the top outlet of the negative electrode electrolyte chamber (3-5) is connected to the inlet of the negative electrode storage tank (3-6). The outlet of the negative electrode storage tank (3-6) is connected to the bottom inlet of the negative electrode electrolyte chamber (3-5) via a second circulation pump (3-4-2).

3. The operating method of the microgrid system of liquid flow battery and hydrogen energy storage according to claim 2, characterized in that: The hydrogen outlet of the electrolyzer (4-1) is connected to the inlet of the hydrogen storage device (4-2), and the oxygen outlet of the electrolyzer (4-1) is connected to the inlet of the oxygen storage device (4-4).

4. The operating method of the microgrid system of liquid flow battery and hydrogen energy storage according to claim 2, characterized in that: The outlet of the hydrogen storage device (4-2) is connected to the inlet of the hydrogen utilization unit (4-3), and the outlet of the oxygen storage device (4-4) is connected to the oxygen utilization unit (4-5).

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