Off-grid liquid flow energy storage system and new energy and coal chemical coupling hydrogen production system

Abstract

The invention relates to the technical field of electric power, in particular to an off-grid liquid flow energy storage system and a new energy and coal chemical coupling hydrogen production system. The off-grid liquid flow energy storage system comprises an energy storage converter, a liquid flow battery and an energy storage control unit, and the energy storage converter is connected between the liquid flow battery and the at least one new energy power generation system and used for achieving alternating current / direct current conversion and voltage conversion; and the energy storage control unit is connected with the energy storage converter and the flow battery and is used for controlling the flow battery and the energy storage converter. The energy storage control unit outputs stable voltage and frequency by controlling the flow battery and the energy storage converter, and provides stable voltage and frequency for the off-grid new energy and coal chemical coupling hydrogen production system. In addition, the new energy power generation system utilizes renewable energy sources, dependence on fossil fuel can be reduced, and environmental protection is facilitated.

Description

Technical Field

[0001] The present disclosure relates to the field of electric power technology, and in particular to an off-grid liquid flow energy storage system and a new energy and coal chemical coupled hydrogen production system. Background Art

[0002] Building a clean, low-carbon, safe and efficient modern energy system is the current development direction of my country's energy transformation. At present, in the scenario of coal chemical industry and new energy coupling, the grid-connected centralized hydrogen production solution is mostly adopted to convert the excess energy of new energy into hydrogen energy as a raw material for coal chemical enterprises or for power generation. However, the grid-connected centralized hydrogen production solution has low environmental protection and sustainability and is greatly affected by the power grid. Summary of the invention

[0003] The purpose of the present disclosure is to provide an off-grid liquid flow energy storage system and a new energy and coal chemical coupled hydrogen production system to ensure the stability of the output voltage and frequency of the off-grid liquid flow energy storage system and improve environmental protection and sustainability.

[0004] In order to achieve the above-mentioned object, the present disclosure provides, in a first aspect, an off-grid liquid flow energy storage system, comprising an energy storage converter, a liquid flow battery and an energy storage control unit;

[0005] The energy storage converter is connected between the flow battery and at least one new energy power generation system to realize AC / DC conversion and voltage conversion;

[0006] The energy storage control unit is connected to the energy storage converter and the liquid flow battery, and is used to control the liquid flow battery and the energy storage converter so that the off-grid liquid flow energy storage system outputs a target voltage and a target frequency.

[0007] Optionally, the energy storage control unit is further used for:

[0008] When the initial operation or non-operation time of the liquid flow battery reaches a first time threshold, the liquid flow battery is placed in a low-voltage start-up mode by controlling the energy storage converter.

[0009] Optionally, the energy storage converter includes an inverter circuit and a DC side circuit, and the new energy power generation system is connected to the flow battery through the inverter circuit and the DC side circuit;

[0010] The DC side circuit includes a first capacitor, a second capacitor, a first bridge arm, a second bridge arm, a switch component, a first inductor and a second inductor;

[0011] The first capacitor and the second capacitor are connected in series to obtain a capacitor branch, and the inverter circuit is connected in parallel with the capacitor branch, the first bridge arm, and the second bridge arm;

[0012] The first end of the first inductor is connected to the midpoint of the first bridge arm, and the second end of the first inductor is connected to the positive electrode of the liquid flow battery;

[0013] The first end of the second inductor is connected to the midpoint of the second bridge arm, the second end of the second inductor is connected to the first contact of the switch component, and the second end of the second bridge arm is connected to the second contact of the switch component;

[0014] The first fixed end of the switch assembly is connected to the positive electrode of the liquid flow battery, and the second fixed end of the switch assembly is connected to the negative electrode of the liquid flow battery.

[0015] Optionally, the energy storage control unit is used to:

[0016] When the initial operation or non-operation time of the liquid flow battery reaches the first time threshold, controlling the circuit between the first contact and the second fixed end in the switch assembly to be conductive, so that the liquid flow battery is in a low-voltage starting mode;

[0017] When the operating time of the liquid flow battery reaches a second time threshold, the circuit between the first contact and the first fixed end in the switch assembly is controlled to be conductive, and the circuit between the second contact and the second fixed end in the switch assembly is controlled to be conductive, so that the liquid flow battery is in a normal operating mode.

[0018] Optionally, the energy storage control unit includes:

[0019] A data acquisition module, used to collect first state information of the flow battery and second state information of the energy storage converter, wherein the first state information includes at least one of the stack voltage, stack current, SOC information, liquid level information, flow information, pressure information, temperature information of the flow battery, and internal digital switch quantity information of the flow battery, and the second state information includes at least one of the new energy power generation system voltage, new energy power generation system current, energy storage converter voltage, filter voltage and filter current;

[0020] A network control module, connected to the data acquisition module, for generating a control signal for controlling the operating state of the energy storage converter according to the first state information and the second state information, so that the off-grid liquid flow energy storage system outputs a target voltage and a target frequency;

[0021] A battery management control module is connected to the data acquisition module and is used to control the operating state of the flow battery according to the first state information and the second state information.

[0022] Optionally, the battery management control module is used to:

[0023] According to the first state information and the second state information, a preset liquid flow battery operating range, fault-tolerant control requirements and system fault information, the action of the actuator in the liquid flow battery is controlled, wherein the actuator includes at least one of a flow pump, a valve and a circuit breaker.

[0024] Optionally, the energy storage control unit further includes:

[0025] A protection control module is connected to the data acquisition module, the networking control module and the battery management control module, and is used to determine the health status of the liquid flow battery according to the first status information, and determine the health status of the energy storage inverter according to the second status information, so as to provide a control basis for the networking control module and the battery management control module.

[0026] Optionally, the new energy power generation system includes at least one of a photovoltaic power generation system and a wind power generation system.

[0027] The second aspect of the present disclosure provides a new energy and coal chemical coupling hydrogen production system, comprising: a new energy power generation system, a hydrogen production system, a heat generation and heat storage system, a coupling unit, and the off-grid liquid flow energy storage system provided in the first aspect of the present disclosure;

[0028] The hydrogen production system is connected to the new energy power generation system to provide hydrogen;

[0029] The heating and heat storage system is connected to the new energy power generation system and is used to provide thermal energy to the hydrogen production system through the coupling unit.

[0030] Optionally, the heating and heat storage system is used for:

[0031] When the hydrogen production system stops producing hydrogen, the temperature of the hydrogen production system is controlled by the coupling unit to be maintained at a temperature threshold.

[0032] In the above technical solution, the energy storage inverter is connected between the liquid flow battery and at least one new energy power generation system to realize the conversion of AC / DC power and voltage conversion; the energy storage control unit is connected to the energy storage inverter and the liquid flow battery to control the liquid flow battery and the energy storage inverter so that the off-grid liquid flow energy storage system outputs the target voltage and target frequency. In this way, based on the control of the liquid flow battery and the energy storage inverter by the energy storage control unit, the stability of the output voltage and frequency of the off-grid liquid flow energy storage system can be ensured, so that the new energy and coal chemical coupled hydrogen production system containing the off-grid liquid flow energy storage system can operate stably. In addition, the new energy power generation system uses renewable energy, which can reduce dependence on fossil fuels, reduce greenhouse gas emissions, and is beneficial to environmental protection; if the off-grid liquid flow energy storage system is connected to a variety of new energy power generation systems, it can reduce dependence on a single external energy source and improve the safety and stability of energy supply.

[0033] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0035] Figure 1 It is a block diagram of an off-grid liquid flow energy storage system provided by an exemplary embodiment of the present disclosure.

[0036] Figure 2 is a circuit diagram of an energy storage converter provided by an exemplary embodiment of the present disclosure.

[0037] Figure 3 It is a schematic diagram of an energy storage converter when a liquid flow battery enters a low-voltage startup mode, provided by an exemplary embodiment of the present disclosure.

[0038] Figure 4 It is a schematic diagram of an energy storage converter when a liquid flow battery enters a normal operating mode, provided by an exemplary embodiment of the present disclosure.

[0039] Figure 5 is a schematic diagram of an energy storage control unit provided by an exemplary embodiment of the present disclosure.

[0040] Figure 6 is a schematic diagram of an energy storage control unit provided by an exemplary embodiment of the present disclosure.

[0041] Figure 7 It is a schematic diagram of a new energy and coal chemical coupling hydrogen production system provided by an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0042] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0043] It should be noted that all actions of acquiring signals, information or data in the present disclosure are carried out in compliance with the relevant data protection laws and policies of the country where the device is located and with the authorization given by the owner of the corresponding device.

[0044] Figure 1 is a block diagram of an off-grid liquid flow energy storage system 10 provided by an exemplary embodiment of the present disclosure. Figure 1 As shown, the off-grid liquid flow energy storage system 10 includes an energy storage converter 101 , a liquid flow battery 102 and an energy storage control unit 103 .

[0045] The energy storage converter 101 is connected between the flow battery 102 and at least one new energy power generation system 11 to realize AC / DC conversion and voltage conversion;

[0046] The energy storage control unit 103 is connected to the energy storage converter 101 and the liquid flow battery 102, and is used to control the liquid flow battery 102 and the energy storage converter 101 so that the off-grid liquid flow energy storage system 10 outputs a target voltage and a target frequency.

[0047] For example, the new energy power generation system 11 may include at least one of a photovoltaic power generation system and a wind power generation system. The energy storage converter 101 may convert the alternating current output by the new energy power generation system 11 into direct current, and adjust its voltage so that the liquid flow battery 102 obtains energy that meets its operating requirements. For example, the energy storage converter 101 may include an inverter circuit and a DC side circuit (wherein the DC side circuit may include a DC-DC converter), both of which may include multiple power devices, and the energy storage control unit 103 may control the number of power devices in the energy storage converter 101 that are turned on and the on-duty cycle, so that the off-grid liquid flow energy storage system 10 outputs a target voltage and a target frequency. Among them, the target voltage and target frequency can be pre-set based on actual needs, and there is no limitation here. In this way, the off-grid liquid flow energy storage system 10 can output a stable voltage and frequency, and integrate with a variety of energy sources to provide high-quality electricity to support new energy power generation and load energy consumption.

[0048] The liquid flow battery 102 has no potential explosion or fire hazard, so it is relatively safe, and accordingly, the safety of the off-grid liquid flow energy storage system 10 in which it is located is also relatively high. The energy storage inverter 101 is connected to at least one new energy power generation system 11. Compared with connecting the energy storage inverter 101 to a power grid that generates electricity through coal, it can avoid its dependence on the power grid, reduce dependence on fossil fuels, and is beneficial to environmental protection. In addition, the connection of the off-grid liquid flow energy storage system 10 with multiple new energy power generation systems 11 can reduce dependence on a single external energy source and improve the safety and stability of energy supply. Integrating the module for controlling the energy storage inverter 101 and the liquid flow battery 102 in the energy storage control unit 103 can simplify the control architecture, reduce the amount of information interaction, and thereby improve the reliability of the energy storage control unit 103.

[0049] In the above technical solution, based on the control of the liquid flow battery 102 and the energy storage converter 101 by the energy storage control unit 103, the stability of the output voltage and frequency of the off-grid liquid flow energy storage system 10 can be ensured, so that the new energy and coal chemical coupled hydrogen production system containing the off-grid liquid flow energy storage system 10 can operate stably. In addition, the new energy power generation system 11 uses renewable energy, which can reduce dependence on fossil fuels, reduce greenhouse gas emissions, and is beneficial to environmental protection; if the off-grid liquid flow energy storage system 10 is connected to a variety of new energy power generation systems 11, it can reduce dependence on a single external energy source and improve the safety and stability of energy supply.

[0050] In an optional embodiment, the energy storage control unit 103 may also be used for:

[0051] When the liquid flow battery 102 is initially operated or has not been operated for a time period that reaches a first time period threshold, the liquid flow battery 102 is placed in a low-voltage start-up mode by controlling the energy storage converter 101 .

[0052] For example, the first duration threshold can be pre-set based on actual needs. If the duration that the flow battery 102 has not been in operation reaches the first duration threshold, it can be determined that the flow battery 102 has not been in operation for a long time. In order to achieve safe activation, the energy storage control unit 103 can control the flow battery 102 to enter a low-voltage start-up mode, for example, control the battery to start at 0V. If the flow battery 102 is in the initial operation state, it can be determined that the flow battery 102 has not completed the startup. At this time, the flow battery 102 cannot enter the normal operation state. The energy storage control unit 103 can still control the flow battery 102 to be in a low-voltage start-up mode. For example, the function of controlling the energy storage inverter 101 so that the flow battery 102 is in a low-voltage start-up mode can be implemented by the networking control module 1032 in the energy storage control unit 103. In this way, the safe activation of the main characteristics of the flow battery 102 can be achieved through low-voltage startup, so that the flow battery 102 meets the networking operation conditions. Among them, the grid-building operation condition is determined based on the grid-building control strategy adopted by the energy storage control unit 103. The grid-building control strategy in the present disclosure may be a grid-building control strategy in the related art, which will not be described in detail here.

[0053] Figure 2 1 is a circuit diagram of an energy storage converter 101 provided by an exemplary embodiment of the present disclosure. Figure 2 As shown, the energy storage converter 101 may include an inverter circuit 1011 and a DC side circuit 1012, and the DC side circuit 1012 may include a first capacitor C1, a second capacitor C2, a first bridge arm, a second bridge arm, a switch component, a first inductor L1, and a second inductor L2. The new energy power generation system 11 may be connected to the flow battery 102 via the inverter circuit 1011 and the DC side circuit 1012.

[0054] The first capacitor C1 and the second capacitor C2 are connected in series to obtain a capacitor branch, and the inverter circuit 1011 is connected in parallel with the capacitor branch, the first bridge arm, and the second bridge arm; the first end of the first inductor L1 is connected to the midpoint of the first bridge arm, and the second end of the first inductor L1 is connected to the positive electrode of the liquid flow battery 102; the first end of the second inductor L2 is connected to the midpoint of the second bridge arm, the second end of the second inductor L2 is connected to the first contact A of the switch component, and the second end of the second bridge arm is connected to the second contact B of the switch component; the first fixed end a of the switch component is connected to the positive electrode of the liquid flow battery 102, and the second fixed end b of the switch component is connected to the negative electrode of the liquid flow battery 102.

[0055] exist Figure 2In the plane direction shown, the first ends of the first inductor L1 and the second inductor L2 are the left ends, the second ends of the first inductor L1 and the second inductor L2 are the right ends, the first ends of the first bridge arm and the second bridge arm are the upper ends, and the second ends of the first bridge arm and the second bridge arm are the lower ends. Among them, the bridge arm in the present disclosure is a circuit structure in which two power devices are connected in the form of a totem pole, with the middle point as the output, and the upper bridge arm of each bridge arm includes a power device, and the lower bridge arm includes another power device. The power device involved in the present disclosure can be any one of a thyristor, a MOS tube (MOSFET, insulated gate field effect transistor), and an IGBT (insulated gate bipolar transistor). In order to prevent the power device from being damaged by reverse voltage, each power device can be connected in reverse parallel with a parasitic diode and used as an upper bridge arm or a lower bridge arm in the bridge arm. As shown Figure 2 As shown, the first bridge arm is composed of the first power device T u1 and the second power device T u2 The second bridge arm is composed of the third power device T v1 and the fourth power device T v2 The switch assembly includes: a first contact point A connected to the second end of the second inductor L2, a second contact point B connected to the second end of the second bridge arm, a first fixed end a connected to the positive electrode of the flow battery 102, and a second fixed end b connected to the negative electrode of the flow battery 102. The control of the internal conduction circuit of the switch assembly can be achieved by controlling the movable part connected to the fixed end to contact with any contact point, so that the flow battery 102 is in different modes.

[0056] In an optional embodiment, the energy storage control unit 103 may be used to:

[0057] When the liquid flow battery 102 is initially operated or has not been operated for a time period that reaches a first time period threshold, the circuit between the first contact point A and the second fixed end b in the control switch assembly is turned on, so that the liquid flow battery 102 is in a low-voltage start-up mode;

[0058] When the operating time of the liquid flow battery 102 reaches the second time threshold, the line between the first contact A and the first fixed end a in the control switch assembly is controlled to be conductive, and the line between the second contact B and the second fixed end b in the control switch assembly is controlled to be conductive, so that the liquid flow battery 102 is in normal operating mode.

[0059] For example, when the liquid flow battery 102 is initially operated or the non-operation time reaches a first time threshold, the line between the first contact A and the second fixed end b can be controlled to be conductive, and the conductive circuit in the energy storage converter 101 can be as follows: Figure 3 As shown, in this way, the flow battery 102 can be placed in a low voltage startup mode.

[0060] For example, the second duration threshold can be preset based on actual needs. If the running time of the flow battery 102 reaches the second duration threshold, it can be determined that the flow battery 102 has completed startup, and the flow battery 102 can enter a normal operating state. The line between the first contact A and the first fixed end a in the switch assembly can be controlled to be conductive, and the line between the second contact B and the second fixed end b in the switch assembly can be controlled to be conductive. The conductive circuit in the energy storage converter 101 can be as follows Figure 4 As shown, in this way, the flow battery 102 can be placed in a normal operating mode.

[0061] The present disclosure provides a novel liquid flow energy storage system control architecture, which integrates the control management system of the energy storage converter 101 and the battery energy management system of the liquid flow battery 102 to obtain the energy storage control unit 103 provided by the present disclosure, so as to adopt a set of control architecture for centralized control. Figure 5 FIG. 1 is a schematic diagram of an energy storage control unit 103 provided by an exemplary embodiment of the present disclosure. Figure 5 As shown, the energy storage control unit 103 may include a data acquisition module 1031 , a networking control module 1032 and a battery management control module 1033 .

[0062] The data acquisition module 1031 is used to collect the first state information of the flow battery 102 and the second state information of the energy storage converter 101 .

[0063] For example, the first state information may include at least one of the stack voltage, stack current, SOC information, liquid level information, flow information, pressure information, temperature information, and digital switch quantity information inside the flow battery 102. The flow battery 102 may include actuators such as flow pumps, valves, and circuit breakers. By controlling the above actuators, the operating state of the flow battery 102 can be controlled, such as controlling its output current and voltage, wherein the digital switch quantity information inside the flow battery 102 can be used to characterize the current state of the actuator.

[0064] The second state information may include at least one of the voltage of the new energy power generation system, the current of the new energy power generation system, the voltage of the energy storage converter, the voltage of the filter, and the current of the filter. The energy storage converter 101 and the new energy power generation system 11 may be connected through a filter, and the energy storage converter 101 and the liquid flow battery 102 may also be connected through a filter. In this way, by collecting and applying the filter status, the control of the off-grid liquid flow energy storage system 10 can be more accurately achieved.

[0065] The network control module 1032 is connected to the data acquisition module 1031, and is used to generate a control signal for controlling the operating state of the energy storage converter 101 according to the first state information and the second state information, so that the off-grid liquid flow energy storage system 10 outputs the target voltage and target frequency.

[0066] For example, the grid control module 1032 can obtain a PWM control signal based on the first state information, the second state information and the internal grid control strategy to control the opening and closing of the power devices inside the energy storage inverter 101, so that the off-grid liquid flow energy storage system 10 outputs a stable target voltage and target frequency, thereby enabling the new energy and coal chemical coupled hydrogen production system containing the off-grid liquid flow energy storage system 10 to operate stably.

[0067] The battery management control module 1033 is connected to the data acquisition module 1031 and is used to control the operating state of the flow battery 102 according to the first state information and the second state information.

[0068] For example, the battery management control module 1033 can control the actions of the actuators in the flow battery 102 according to the first state information, the second state information, the preset operation range of the flow battery 102, the fault tolerance control requirements and the system fault information. In this way, the operation state of the flow battery 102 can be controlled.

[0069] Among them, the actuator includes at least one of a flow pump, a valve and a circuit breaker. The operating range and fault-tolerant control requirements of the liquid flow battery 102 can be preset, and the system fault information can include the fault information of the liquid flow battery 102, and can also include the fault information of the energy storage converter 101, and can also include the fault information of other components in the new energy and coal chemical coupled hydrogen production system containing the off-grid liquid flow energy storage system 10. The battery management control module 1033 can monitor the operating status of the liquid flow battery 102 module in real time, and control the internal flow pump, valve, circuit breaker and other actuators in real time according to the operating range, system fault information and fault-tolerant control requirements of the liquid flow battery 102, to ensure that the entire new energy and coal chemical coupled hydrogen production system containing the off-grid liquid flow energy storage system 10 can operate for a long time, reliably and stably.

[0070] like Figure 5 As shown, the energy storage control unit 103 can exchange data with the energy management system 20. The energy management system 20 can exchange information with the new energy and coal chemical coupled hydrogen production system containing the off-grid liquid flow energy storage system 10 to realize monitoring and control of the new energy and coal chemical coupled hydrogen production system.

[0071] like Figure 6 As shown, the energy storage control unit 103 may also include:

[0072] The protection control module 1034 is connected to the data acquisition module 1031, the networking control module 1032 and the battery management control module 1033, and is used to determine the health status of the liquid flow battery 102 according to the first status information, and determine the health status of the energy storage inverter 101 according to the second status information, so as to provide a control basis for the networking control module 1032 and the battery management control module 1033.

[0073] For example, the protection control module 1034 can perform real-time operation detection on the flow battery 102 and the energy storage converter 101, determine the health status of the flow battery 102 and the energy storage converter 101, and transmit the information of feedback of the health status of each to the corresponding control module, such as transmitting the information of feedback of the health status of the flow battery 102 to the battery management control module 1033, and transmitting the information of feedback of the health status of the energy storage converter 101 to the network control module 1032, so as to provide a control basis for each control module. Among them, the protection control module 1034 can determine the health status of the flow battery 102 and the energy storage converter 101 based on the pre-trained health detection model, and the health detection model can be a model trained by machine learning. For example, the first state information and the second state information can be input into the health detection model, and the health detection model can output the health status of the flow battery 102 and the energy storage converter 101 at the same time. The health detection model can be stored in the protection control module 1034, or it can be stored in a third-party platform, and it can be called from the third party each time it is used, which is not specifically limited here.

[0074] In this way, based on the protection control module 1034, the fault detection of the flow battery 102 and the energy storage converter 101 can be synchronized and real-time, thereby improving the system fault detection response speed and fault-tolerant control capability.

[0075] In an optional embodiment, the new energy power generation system 11 may include at least one of a photovoltaic power generation system and a wind power generation system.

[0076] The present disclosure also provides a new energy and coal chemical coupled hydrogen production system 12. The new energy and coal chemical coupled hydrogen production system 12 comprises a new energy power generation system 11, a hydrogen production system 12, a heat generation and heat storage system 14, a coupling unit 13, and an off-grid liquid flow energy storage system 10 as described in any of the above embodiments.

[0077] The hydrogen production system 12 is connected to the new energy power generation system 11 to provide hydrogen; the heat storage system 14 is connected to the new energy power generation system 11 to provide thermal energy to the hydrogen production system 12 through the coupling unit 13 .

[0078] For example, the hydrogen production system 12 may include at least one of an alkaline water electrolysis hydrogen production unit and a proton exchange membrane water electrolysis hydrogen production unit. The heating and heat storage system 14 may include a high-temperature hydrogen production and heat storage device based on carbon materials and a heating and heat storage device based on magnesium bricks. The heating and heat storage system 14 provides the required heat energy for the hydrogen production system 12 through the coupling unit 13, which is not limited to heat transfer methods such as heat conduction and heat radiation.

[0079] like Figure 7 As shown, the hydrogen production system 12 can provide hydrogen for coal chemical enterprises, and the heat generation and storage system 14 can provide steam for coal chemical enterprises. Figure 7 In the corresponding application scenario, based on the coal chemical process, coal and water can be gasified to produce water gas, and after adding hydrogen, polyglycolic acid (PGA) can be produced through synthesis and processing. The oxygen, hydrogen and heat energy required in the entire process can be provided by the new energy and coal chemical coupling hydrogen production system 12, and the new energy and coal chemical coupling hydrogen production system 12 operates in off-grid mode. Among them, the new energy power generation system 11 provides power support; the off-grid liquid flow energy storage system 10 provides network support, output target voltage and target frequency; the hydrogen and oxygen generated by the hydrogen production system 12 are used as the main load output; the heating and heat storage system 14 can store the heat energy converted from electrical energy, and the steam output by the heating and heat storage system 14 can be used for the coal chemical process and as an adjustable load for absorbing new energy.

[0080] In this way, the new energy and coal chemical coupling hydrogen production system includes an off-grid liquid flow energy storage system 10, a new energy power generation system 11, a hydrogen production system 12, a heat storage system 14 and a coupling unit 13; the energy storage control unit 103 in the off-grid liquid flow energy storage system 10 can output a stable voltage and frequency by controlling the liquid flow battery and the energy storage converter, and provide a stable voltage and frequency for the off-grid new energy and coal chemical coupling hydrogen production system. In addition, for the off-grid liquid flow energy storage system 10, a new control architecture of the liquid flow energy storage system is proposed, which adopts a unified control module to make the fault detection of the liquid flow battery 102 and the energy storage converter 101 synchronous and real-time, thereby improving the system fault detection response speed and fault-tolerant control capability.

[0081] like Figure 7 As shown, the energy management system 20 can exchange information with the new energy power generation system 11, the hydrogen production system 12, the heat storage system 14, and the off-grid liquid flow energy storage system 10 in the new energy and coal chemical coupling hydrogen production system 12 to realize the monitoring and control of the new energy and coal chemical coupling hydrogen production system 12.

[0082] In an optional embodiment, the heat storage system 14 may be used to control the temperature of the hydrogen production system 12 to be maintained at a temperature threshold through the coupling unit 13 when the hydrogen production system 12 stops producing hydrogen.

[0083] For example, the temperature threshold can be preset based on actual needs. For example, if the hydrogen production system 12 can electrolyze to obtain hydrogen and oxygen at 70°C, the temperature threshold can be set at 60°C to enable the hydrogen production system 12 to start hydrogen production through short-term heating. In this way, the start-up time of the hydrogen production device can be shortened, and the efficiency of the hydrogen production system 12 coupled with new energy and coal chemical industry can be improved.

[0084] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0085] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0086] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. An off-grid liquid flow energy storage system, characterized in that: The off-grid liquid flow energy storage system includes an energy storage converter, a liquid flow battery and an energy storage control unit; The energy storage converter is connected between the flow battery and at least one new energy power generation system to realize AC / DC conversion and voltage conversion; The energy storage control unit is connected to the energy storage converter and the liquid flow battery, and is used to control the liquid flow battery and the energy storage converter so that the off-grid liquid flow energy storage system outputs a target voltage and a target frequency.

2. The off-grid liquid flow energy storage system according to claim 1, characterized in that: The energy storage control unit is also used for: When the initial operation or non-operation time of the liquid flow battery reaches a first time threshold, the liquid flow battery is placed in a low-voltage start-up mode by controlling the energy storage converter.

3. The off-grid liquid flow energy storage system according to claim 2, characterized in that: The energy storage converter includes an inverter circuit and a DC side circuit, and the new energy power generation system is connected to the flow battery through the inverter circuit and the DC side circuit; The DC side circuit includes a first capacitor, a second capacitor, a first bridge arm, a second bridge arm, a switch component, a first inductor and a second inductor; The first capacitor and the second capacitor are connected in series to obtain a capacitor branch, and the inverter circuit is connected in parallel with the capacitor branch, the first bridge arm, and the second bridge arm; The first end of the first inductor is connected to the midpoint of the first bridge arm, and the second end of the first inductor is connected to the positive electrode of the liquid flow battery; The first end of the second inductor is connected to the midpoint of the second bridge arm, the second end of the second inductor is connected to the first contact of the switch component, and the second end of the second bridge arm is connected to the second contact of the switch component; The first fixed end of the switch assembly is connected to the positive electrode of the liquid flow battery, and the second fixed end of the switch assembly is connected to the negative electrode of the liquid flow battery.

4. The off-grid liquid flow energy storage system according to claim 3, characterized in that: The energy storage control unit is used for: When the initial operation or non-operation time of the liquid flow battery reaches the first time threshold, controlling the circuit between the first contact and the second fixed end in the switch assembly to be conductive, so that the liquid flow battery is in a low-voltage starting mode; When the operating time of the liquid flow battery reaches a second time threshold, the circuit between the first contact and the first fixed end in the switch assembly is controlled to be conductive, and the circuit between the second contact and the second fixed end in the switch assembly is controlled to be conductive, so that the liquid flow battery is in a normal operating mode.

5. The off-grid liquid flow energy storage system according to claim 1, characterized in that: The energy storage control unit comprises: A data acquisition module, used to collect first state information of the flow battery and second state information of the energy storage converter, wherein the first state information includes at least one of the stack voltage, stack current, SOC information, liquid level information, flow information, pressure information, temperature information of the flow battery, and internal digital switch quantity information of the flow battery, and the second state information includes at least one of the new energy power generation system voltage, new energy power generation system current, energy storage converter voltage, filter voltage and filter current; A network control module, connected to the data acquisition module, for generating a control signal for controlling the operating state of the energy storage converter according to the first state information and the second state information, so that the off-grid liquid flow energy storage system outputs a target voltage and a target frequency; A battery management control module is connected to the data acquisition module and is used to control the operating state of the flow battery according to the first state information and the second state information.

6. The off-grid liquid flow energy storage system according to claim 5, characterized in that: The battery management control module is used for: According to the first state information and the second state information, a preset liquid flow battery operating range, fault-tolerant control requirements and system fault information, the action of the actuator in the liquid flow battery is controlled, wherein the actuator includes at least one of a flow pump, a valve and a circuit breaker.

7. The off-grid liquid flow energy storage system according to claim 5, characterized in that: The energy storage control unit also includes: A protection control module is connected to the data acquisition module, the networking control module and the battery management control module, and is used to determine the health status of the liquid flow battery according to the first status information, and determine the health status of the energy storage inverter according to the second status information, so as to provide a control basis for the networking control module and the battery management control module.

8. The off-grid liquid flow energy storage system according to claim 1, characterized in that: The new energy power generation system includes at least one of a photovoltaic power generation system and a wind power generation system.

9. A new energy and coal chemical coupling hydrogen production system, characterized in that: The new energy and coal chemical industry coupled hydrogen production system comprises a new energy power generation system, a hydrogen production system, a heat generation and heat storage system, a coupling unit, and an off-grid liquid flow energy storage system as described in any one of claims 1 to 8; The hydrogen production system is connected to the new energy power generation system to provide hydrogen; The heating and heat storage system is connected to the new energy power generation system and is used to provide thermal energy to the hydrogen production system through the coupling unit.

10. The new energy and coal chemical industry coupled hydrogen production system according to claim 9, characterized in that: The heating and heat storage system is used for: When the hydrogen production system stops producing hydrogen, the temperature of the hydrogen production system is controlled by the coupling unit to be maintained at a temperature threshold.

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