Black start system and control method of liquid flow battery energy storage system

Abstract

The present invention discloses a black start system for a liquid flow battery energy storage system in the field of liquid flow battery technology and a control method thereof, comprising a liquid flow battery module, an AC / DC converter and a battery management unit; the working state of the liquid flow battery module is monitored and managed by the liquid flow battery, and the output power of the liquid flow battery module is controlled according to the voltage value converted and output by the AC / DC converter; and the battery management unit is also electrically connected to a lithium battery; and when the battery management unit starts the lithium battery based on a black start instruction, the real-time temperature data is compared with the set suitable working temperature; if the real-time temperature data is greater than the suitable working temperature, a cold source connection instruction is sent to a three-phase solenoid valve; if the real-time temperature data is less than or equal to the suitable working temperature, a heat source connection instruction is sent to the three-phase solenoid valve; the reaction rate of the internal electrolyte solution is accelerated, so that the liquid flow battery module generates electricity faster, and the response speed of the black start is improved to ensure the stability of the power system.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid flow batteries, and in particular relates to a black start system for a liquid flow battery energy storage system and a control method thereof. Background Art

[0002] With the widespread application of new energy electric vehicles, battery capacity, safety, health status and endurance have become increasingly the focus of attention. Since traditional batteries have the disadvantages of poor short-term discharge capability, short cycle life and high maintenance cost, the new type of liquid flow battery has become one of the guarantees for the stability of the power system during the operation of new energy vehicles due to its high capacity, wide application range (environment) and long cycle life.

[0003] Since new energy vehicles need to maintain good power stability, when the power system is interrupted, the black start function of the flow battery becomes one of the important indicators for measuring the power system. Summary of the Invention

[0004] The purpose of the present invention is to provide a black start system for a flow battery energy storage system and a control method thereof, so as to improve the response speed of the black start and ensure the stability of the power system.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] Black start system for flow battery energy storage system, including flow battery module, AC / DC converter and battery management unit;

[0007] The flow battery module includes a positive electrode electrolyte storage tank for storing positive electrode electrolyte, a negative electrode electrolyte storage tank for storing negative electrode electrolyte, a battery stack unit and an electrolyte circulation unit for pumping electrolyte;

[0008] The electrolyte circulation unit includes an electrolyte circulation pipeline, a positive electrode electrolyte circulation pump and a negative electrode electrolyte circulation pump;

[0009] The positive electrode or negative electrode of the stack unit is connected to the positive electrolyte storage tank or the negative electrolyte storage tank respectively through the electrolyte circulation pipeline, and the output end of the stack unit is also electrically connected to the battery management unit and the AC / DC converter;

[0010] The AC / DC converter is used to convert direct current or alternating current between the flow battery module and the external circuit;

[0011] The battery management unit is used to monitor and manage the working status of the liquid flow battery module and control the output power of the liquid flow battery module according to the voltage value converted and output by the AC / DC converter; and the battery management unit is also electrically connected to the lithium battery;

[0012] The battery also includes a pre-processing module electrically connected to the battery management unit, the pre-processing module including a temperature sensor for measuring real-time temperature data of the electrolyte in the positive electrolyte storage tank or the negative electrolyte storage tank and a heat exchange tube wound around the positive electrolyte storage tank or the negative electrolyte storage tank, the end of the heat exchange tube away from the positive electrolyte storage tank or the negative electrolyte storage tank is connected to a three-phase solenoid valve, and the end of the three-phase solenoid valve away from the heat exchange tube is respectively connected to a heating mechanism and a cooling mechanism;

[0013] The battery management unit compares the voltage value output by the AC / DC converter with the set reference value. If the voltage value is greater than the reference value, a stop command is sent to the lithium battery. If the voltage value is less than the reference value, a black start command is sent to the battery management unit.

[0014] The battery management unit starts the lithium battery based on the black start instruction and compares the real-time temperature data with the set appropriate working temperature. If the real-time temperature data is greater than the appropriate working temperature, a cold source connection instruction is sent to the three-phase solenoid valve; if the real-time temperature data is less than or equal to the appropriate working temperature, a heat source connection instruction is sent to the three-phase solenoid valve.

[0015] The following beneficial effects are achieved by adopting the above scheme:

[0016] During the operation of the flow battery module, the real-time temperature data in the positive electrode electrolyte storage tank or the negative electrode electrolyte storage tank is detected by the battery management unit, so that the electrolyte in the positive electrode electrolyte storage tank or the negative electrode electrolyte storage tank is at a suitable operating temperature, which facilitates the normal operation of the flow battery module and enables the flow battery module to generate stable power.

[0017] When a black start instruction is executed, the internal electrolyte is heated to accelerate the reaction rate of the internal electrolyte, thereby generating current faster and improving the response speed of the black start to ensure the stability of the power system.

[0018] Furthermore, when the real-time temperature is less than or equal to the suitable working temperature, the battery management unit is also used to calculate the phase difference between the real-time temperature data and the suitable working temperature, and obtain the phase difference ratio between the phase difference value and the suitable working temperature. The continuous connection time of the three-phase solenoid valve corresponding to when the electrolyte reaches the maximum temperature rise temperature after the three-phase solenoid valve is connected when the real-time temperature is equal to the suitable working temperature is used as a reference. The battery management unit corrects the continuous connection time based on the phase difference ratio, and then sends a heat source connection instruction containing the corresponding continuous connection time to the three-phase solenoid valve.

[0019] Beneficial effect: By controlling the continuous connection time of the heat exchange tube, the temperature of the positive electrode electrolyte storage tank or the negative electrode electrolyte storage tank does not exceed the maximum temperature, while increasing the reaction rate of the electrolyte and protecting the safety of the flow battery module.

[0020] Furthermore, it also includes a capacitor for energy storage, the capacitor being located between the AC / DC converter and the external circuit;

[0021] When the battery management unit receives the black start instruction, the battery management unit corrects the output power of the lithium battery based on the rated release voltage of the capacitor.

[0022] Beneficial effect: Through the energy storage function of the capacitor, the power supply pressure of the lithium battery is relieved, thereby extending the continuous working time of the lithium battery.

[0023] Furthermore, the battery management unit is further configured to record the cumulative number of black start instructions within the current time interval, and compare the cumulative number with a set target start value; if the cumulative number is greater than the target start value, a rated release voltage correction instruction is sent to the battery management unit; if the cumulative number is less than the target start value, the operation is terminated;

[0024] The battery management unit obtains the interval start time between the black start instruction at the current time and the black start instruction before the current time based on the rated release voltage correction instruction. The battery management unit obtains the standard charging time for full charging of the capacitor, calculates the charging difference ratio between the standard charging time and the interval start time, and corrects the rated release voltage based on the charging difference ratio. The battery management unit then adjusts the output power of the lithium battery based on the corrected rated release voltage.

[0025] Beneficial effect: Since the electric energy of the capacitor is repeatedly released during the current interval, the electric energy stored in the capacitor is not fully charged, and the power supply ratio of the lithium battery is adjusted, making the lithium battery power supply more accurate.

[0026] Furthermore, a second temperature sensor is provided in the heat exchange tube, and the second temperature sensor is used to measure local temperature change data in the heat exchange tube and send the local temperature change data to the battery management unit;

[0027] The battery management unit is used to calculate the temperature difference between the local temperature change data at the current time and the real-time temperature data, and compare the temperature difference with the set temperature threshold. If the temperature difference is greater than or equal to the temperature threshold, a corresponding flow rate increase or flow rate reduction instruction is generated based on the temperature difference and the real-time flow rate in the heat exchange tube, and the flow rate increase or flow rate reduction instruction is sent to the heating mechanism or the cooling mechanism. If the temperature difference is less than the temperature threshold, a flow rate maintenance instruction is sent to the heating mechanism or the cooling mechanism.

[0028] Beneficial effect: By judging the temperature change of the heat exchange tube, it is easy to determine the temperature difference between the heat exchange tube and the positive electrolyte storage tank or the negative electrolyte storage tank. By accelerating the flow speed in the heating tube, the residence time of the heat exchange medium in the heat exchange tube is reduced, thereby facilitating rapid heat exchange of the positive electrolyte storage tank or the negative electrolyte storage tank.

[0029] Furthermore, the control method of the black start system of the flow battery energy storage system includes the following steps: S1, judging the operating status of the flow battery module, obtaining whether the voltage value output by the AC / DC converter at the current time is greater than the standard value, and if the voltage value is greater than the standard value, entering S3; if the voltage value is less than the standard value, entering S2;

[0030] S2, the black start command is executed, the battery management unit starts the lithium battery, and the capacitor releases the stored energy;

[0031] S2.1. The battery management unit records the cumulative number of black start commands within the current time interval and compares the cumulative number with the set standard start value. If the cumulative number is greater than the standard start value, a rated release voltage correction command is sent to the battery management unit. If the cumulative number is less than the standard start value, the output power of the lithium battery is corrected based on the rated release voltage of the capacitor.

[0032] S2.2. At the same time, the lithium battery or capacitor supplies power to the electrolyte circulation unit and compares the real-time temperature data in the positive electrode electrolyte storage tank or the negative electrode electrolyte storage tank with the suitable operating temperature. If the real-time temperature data is greater than the suitable operating temperature, a cold source connection instruction is sent to the three-phase solenoid valve, and the flow battery module begins to transmit current to the external circuit. If the real-time temperature data is less than or equal to the suitable operating temperature, a heat source connection instruction is sent to the three-phase solenoid valve, and the flow battery module begins to transmit current to the external circuit.

[0033] S3. The battery management unit obtains the current working instructions and adjusts the working status of the flow battery module and the lithium battery.

[0034] Beneficial effect: When executing the black start command, the dual power supply of lithium battery and capacitor is used to reduce the power supply pressure of lithium battery, thereby extending the service life of lithium battery;

[0035] At the same time, by comparing the cumulative number of black start instructions, it is determined whether the power supply status of the capacitor in the current time interval meets the loss requirements of the electrolyte circulation unit. By intelligently adjusting the output power of the lithium battery, it is convenient to ensure the electrolyte circulation of the liquid flow battery module and increase the reaction rate of the electrolyte, thereby improving the protection of the black start of the liquid flow battery module.

[0036] Furthermore, in S2.2, when the liquid flow battery module starts to transmit current to the external circuit, the battery management unit will record the continuous power generation time of the liquid flow battery module, and then compare the continuous power generation time with the set lithium battery charging time. If the continuous power generation time is greater than the lithium battery charging time, a charging instruction will be sent to the lithium battery. If the continuous power generation time is less than the lithium battery charging time, the operation will be terminated.

[0037] Beneficial effect: By determining the continuous power generation time of the liquid flow battery module, the liquid flow battery module is ensured to be in a stable and continuous power generation working state. At this time, the power generation of the liquid flow battery module is sufficient. Without affecting the external circuit supply, the lithium battery is charged to ensure that the lithium battery has sufficient power to execute the black start instruction.

[0038] Furthermore, when the lithium battery executes a charging instruction, the battery management unit is also used to compare the current energy storage of the lithium battery at the current time with the set limit value. If the current energy storage is greater than the limit value, the lithium battery charging is terminated; if the current energy storage is less than the limit value, the lithium battery charging is maintained.

[0039] Beneficial effect: By judging the remaining power of the lithium battery, it is determined whether the lithium battery needs to be charged at the current time to ensure sufficient power of the lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a structural diagram of a flow battery module of a black start system of a flow battery energy storage system according to an embodiment of the present invention.

[0041] Figure 2 Schematic diagram of a black start system for a flow battery energy storage system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following is further described in detail through specific implementation methods:

[0043] The reference numerals in the drawings of the specification include: battery stack unit 1, positive electrode electrolyte storage tank 11, negative electrode electrolyte storage tank 12, battery management unit 2, heat exchange tube 3, electrolyte circulation unit 4, AC / DC converter 5, capacitor 6.

[0044] Example 1

[0045] The embodiment is basically as shown in the attached Figures 1 to 2 Figure 2: Black start system of flow battery energy storage system, including flow battery module, AC / DC converter and battery management unit 2;

[0046] The flow battery module includes a positive electrode electrolyte storage tank 11 for storing positive electrode electrolyte, a negative electrode electrolyte storage tank 12 for storing negative electrode electrolyte, a stack unit 1 and an electrolyte circulation unit 4 for pumping electrolyte;

[0047] The electrolyte circulation unit 4 includes an electrolyte circulation pipeline, a positive electrolyte circulation pump and a negative electrolyte circulation pump;

[0048] The positive electrode or negative electrode of the stack unit 1 is connected to the positive electrolyte storage tank 11 or the negative electrolyte storage tank 12 respectively through the electrolyte circulation pipeline, and the output end of the stack unit 1 is also electrically connected to the battery management unit 2 and the AC / DC converter;

[0049] The AC / DC converter is used to convert direct current or alternating current between the flow battery module and the external circuit;

[0050] The battery management unit 2 is used to monitor and manage the working status of the liquid flow battery module and control the output power of the liquid flow battery module according to the voltage value converted and output by the AC / DC converter; and the battery management unit 2 is also electrically connected to the lithium battery;

[0051] The battery also includes a pre-processing module electrically connected to the battery management unit 2, the pre-processing module including a temperature sensor for measuring real-time temperature data of the electrolyte in the positive electrolyte storage tank 11 or the negative electrolyte storage tank 12 and a heat exchange tube 3 wound around the positive electrolyte storage tank 11 or the negative electrolyte storage tank 12, the end of the heat exchange tube 3 away from the positive electrolyte storage tank 11 or the negative electrolyte storage tank 12 is connected to a three-phase solenoid valve, and the end of the three-phase solenoid valve away from the heat exchange tube 3 is respectively connected to a heating mechanism and a cooling mechanism; (taking a new energy vehicle as an example, the heating mechanism is a PTC thermistor heating system or a heat pump system, and the cooling mechanism is an air-conditioning compressor)

[0052] The battery management unit 2 compares the voltage value output by the AC / DC converter with the set reference value. If the voltage value is greater than the reference value, a stop command is sent to the lithium battery. If the voltage value is less than the reference value, a black start command is sent to the battery management unit 2.

[0053] The battery management unit 2 starts the lithium battery based on the black start instruction and compares the real-time temperature data with the set suitable operating temperature. If the real-time temperature data is greater than the suitable operating temperature, it sends a cold source connection instruction to the three-phase solenoid valve; if the real-time temperature data is less than or equal to the suitable operating temperature, it sends a hot source connection instruction to the three-phase solenoid valve;

[0054] For example, the electrolyte in the positive electrode electrolyte storage tank 11 or the negative electrode electrolyte storage tank 12 is easily affected by the external temperature and changes. When the liquid flow battery module has not been working for a long time or has been working for too long, the real-time temperature data of the electrolyte will not be at the appropriate working temperature, and the reaction rate of the electrolyte will be reduced. By maintaining the appropriate working temperature, the liquid flow battery module can work normally and generate stable power. The electrolyte whose real-time temperature data is less than or equal to the appropriate working temperature is heated, and the internal electrolyte is heated to accelerate the reaction rate of the internal electrolyte, thereby generating current faster and improving the response speed of black start to ensure the stability of the power system.

[0055] The battery management unit 2 is further configured to calculate a phase difference between the real-time temperature data and the appropriate operating temperature, obtain a phase difference ratio between the phase difference and the appropriate operating temperature, and use the continuous connection time of the three-phase solenoid valve corresponding to when the electrolyte reaches the maximum temperature rise after the three-phase solenoid valve is connected when the real-time temperature is equal to the appropriate operating temperature as a reference. The battery management unit 2 corrects the continuous connection time based on the phase difference ratio and then sends a heat source connection instruction containing the corresponding continuous connection time to the three-phase solenoid valve;

[0056] For example, during the heat exchange process between the heat exchange tube 3 and the positive electrode electrolyte storage tank 11 or the negative electrode electrolyte storage tank 12, the longer the continuous connection time of the heat exchange tube 3, the higher the temperature rise of the positive electrode electrolyte storage tank 11 or the negative electrode electrolyte storage tank 12. Therefore, by controlling the continuous connection time of the heat exchange tube 3 so that the temperature rise of the positive electrode electrolyte storage tank 11 or the negative electrode electrolyte storage tank 12 does not exceed the maximum temperature rise, the reaction rate of the electrolyte is increased while ensuring the safety of the flow battery module.

[0057] It also includes a capacitor 6 for energy storage, the capacitor 6 is located between the AC / DC converter and the external circuit;

[0058] When the battery management unit 2 receives the black start instruction, the battery management unit 2 is further configured to record the cumulative number of black start instructions within the current time interval, and compare the cumulative number with the set standard start value. If the cumulative number is greater than the standard start value, a rated release voltage correction instruction is sent to the battery management unit 2. If the cumulative number is less than the standard start value, the output power of the lithium battery is corrected based on the rated release voltage of the capacitor 6.

[0059] The battery management unit 2 obtains the interval start time between the black start instruction at the current time and the black start instruction before the current time based on the rated release voltage correction instruction. The battery management unit 2 obtains the standard charging time for the capacitor 6 to be fully charged, and calculates the charging difference ratio between the standard charging time and the interval start time, and corrects the rated release voltage based on the charging difference ratio. The battery management unit 2 then adjusts the output power of the lithium battery based on the corrected rated release voltage.

[0060] For example, the energy storage function of capacitor 6 can be used to relieve the power supply pressure of the lithium battery and extend the continuous working time of the lithium battery. At the same time, when the liquid flow battery module is repeatedly started, the immediate release of electric energy by capacitor 6 has a direct effect on the liquid flow battery module to compensate for the problem of delayed response time of the lithium battery, thereby improving the response speed of black start. At the same time, due to the repeated release of electric energy of capacitor 6 in the current interval time, the electricity stored in capacitor 6 is not fully charged, and the power supply ratio of the lithium battery is adjusted to make the lithium battery power supply more accurate.

[0061] Example 2

[0062] The difference from the above embodiment is that a second temperature sensor is further provided in the heat exchange tube 3, and the second temperature sensor is used to measure the local temperature change data in the heat exchange tube 3 and send the local temperature change data to the battery management unit 2;

[0063] The battery management unit 2 is used to calculate the temperature difference between the local temperature change data at the current time and the real-time temperature data, and compare the temperature difference with the set temperature threshold. If the temperature difference is greater than or equal to the temperature threshold, a corresponding flow rate increase or flow rate reduction instruction is generated based on the temperature difference and the real-time flow rate in the heat exchange tube 3, and the flow rate increase or flow rate reduction instruction is sent to the heating mechanism or the cooling mechanism. If the temperature difference is less than the temperature threshold, a flow rate maintenance instruction is sent to the heating mechanism or the cooling mechanism.

[0064] The specific implementation process is as follows: by judging the temperature change of the heat exchange tube 3, it is convenient to determine the temperature difference between the heat exchange tube 3 and the positive electrode electrolyte storage tank 11 or the negative electrode electrolyte storage tank 12, and by accelerating the flow speed in the heating tube to reduce the residence time of the heat exchange medium in the heat exchange tube 3, thereby facilitating the rapid heat exchange of the positive electrode electrolyte storage tank 11 or the negative electrode electrolyte storage tank 12.

[0065] Example 3

[0066] The difference from the above embodiment is that the control method of the black start system of the flow battery energy storage system includes the following steps: S1, judging the operating status of the flow battery module, obtaining whether the voltage value output by the AC / DC converter at the current time is greater than the standard value, and if the voltage value is greater than the standard value, entering S3; if the voltage value is less than the standard value, entering S2;

[0067] S2, the black start instruction is executed, the battery management unit 2 starts the lithium battery, and the capacitor releases the stored energy;

[0068] S2.1. Battery management unit 2 records the cumulative number of black start instructions within the current time interval and compares the cumulative number with the set standard start value. If the cumulative number is greater than the standard start value, a rated release voltage correction instruction is sent to battery management unit 2. If the cumulative number is less than the standard start value, the output power of the lithium battery is corrected based on the rated release voltage of capacitor 6.

[0069] S2.2. At the same time, the lithium battery or capacitor supplies power to the electrolyte circulation unit 4 and compares the real-time temperature data in the positive electrolyte storage tank 11 or the negative electrolyte storage tank 12 with the suitable operating temperature. If the real-time temperature data is greater than the suitable operating temperature, a cold source connection instruction is sent to the three-phase solenoid valve, and the flow battery module begins to transmit current to the external circuit. If the real-time temperature data is less than or equal to the suitable operating temperature, a heat source connection instruction is sent to the three-phase solenoid valve, and the flow battery module begins to transmit current to the external circuit.

[0070] S3. The battery management unit 2 obtains the current working instructions and adjusts the working status of the flow battery module and the lithium battery.

[0071] This embodiment is a supplementary explanation of embodiment 1, and the beneficial effects achieved are the same, so this embodiment will not be repeated.

[0072] Example 4

[0073] The difference from the above embodiment is that in S2.2, when the liquid flow battery module starts to transmit current to the external circuit, the battery management unit 2 will record the continuous power generation time of the liquid flow battery module, and then compare the continuous power generation time with the set lithium battery charging time. If the continuous power generation time is greater than the lithium battery charging time, a charging instruction is sent to the lithium battery. The battery management unit 2 is also used to compare the current energy storage of the lithium battery at the current time with the set limit value. If the current energy storage is greater than the limit value, the lithium battery charging is terminated. If the current energy storage is less than the limit value, the lithium battery charging is maintained. If the continuous power generation time is less than the lithium battery charging time, it is terminated.

[0074] The specific implementation process is as follows: by determining the continuous power generation time of the liquid flow battery module to ensure that the liquid flow battery module is in a stable and continuous power generation working state. At this time, the power generation of the liquid flow battery module is sufficient. Without affecting the external circuit supply, the lithium battery is charged to ensure that the lithium battery has sufficient power to execute the black start command.

[0075] The above is only an embodiment of the present invention, and common knowledge such as the specific structure and / or characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. Black start system of flow battery energy storage system, characterized by: Includes flow battery module, AC / DC converter and battery management unit; The flow battery module includes a positive electrode electrolyte storage tank for storing positive electrode electrolyte, a negative electrode electrolyte storage tank for storing negative electrode electrolyte, a battery stack unit and an electrolyte circulation unit for pumping electrolyte; The electrolyte circulation unit includes an electrolyte circulation pipeline, a positive electrode electrolyte circulation pump and a negative electrode electrolyte circulation pump; The positive electrode or negative electrode of the stack unit is connected to the positive electrolyte storage tank or the negative electrolyte storage tank respectively through the electrolyte circulation pipeline, and the output end of the stack unit is also electrically connected to the battery management unit and the AC / DC converter; The AC / DC converter is used to convert direct current or alternating current between the flow battery module and the external circuit; The battery management unit is used to monitor and manage the working status of the liquid flow battery module and control the output power of the liquid flow battery module according to the voltage value converted and output by the AC / DC converter; and the battery management unit is also electrically connected to the lithium battery; The battery also includes a pre-processing module electrically connected to the battery management unit, the pre-processing module including a temperature sensor for measuring real-time temperature data of the electrolyte in the positive electrolyte storage tank or the negative electrolyte storage tank and a heat exchange tube wound around the positive electrolyte storage tank or the negative electrolyte storage tank, the end of the heat exchange tube away from the positive electrolyte storage tank or the negative electrolyte storage tank is connected to a three-phase solenoid valve, and the end of the three-phase solenoid valve away from the heat exchange tube is respectively connected to a heating mechanism and a cooling mechanism; The battery management unit compares the voltage value output by the AC / DC converter with the set standard value. If the voltage value is greater than the standard value, a stop command is sent to the lithium battery. If the voltage value is less than the standard value, a black start command is sent to the battery management unit. The battery management unit starts the lithium battery based on the black start instruction and compares the real-time temperature data with the set suitable working temperature. If the real-time temperature data is greater than the suitable working temperature, a cold source connection instruction is sent to the three-phase solenoid valve. If the real-time temperature data is less than or equal to the suitable working temperature, a heat source connection instruction is sent to the three-phase solenoid valve. The battery management unit is also used to calculate the phase difference between the real-time temperature data and the suitable working temperature, obtain the phase difference ratio between the phase difference value and the suitable working temperature, and use the continuous connection time of the three-phase solenoid valve corresponding to the time when the electrolyte reaches the maximum temperature rise temperature after the three-phase solenoid valve is connected when the real-time temperature is equal to the suitable working temperature as a reference. The battery management unit corrects the continuous connection time based on the phase difference ratio and then sends a heat source connection instruction containing the corresponding continuous connection time to the three-phase solenoid valve; It also includes a capacitor for energy storage, the capacitor being located between the AC / DC converter and the external circuit; When the battery management unit receives the black start instruction, the battery management unit corrects the output power of the lithium battery based on the rated release voltage of the capacitor.

2. The black start system of the flow battery energy storage system according to claim 1, characterized in that: The battery management unit is further configured to record the cumulative number of black start instructions within the current time interval, and compare the cumulative number with a set standard start value. If the cumulative number is greater than the standard start value, a rated release voltage correction instruction is sent to the battery management unit; if the cumulative number is less than the standard start value, the operation is terminated. The battery management unit obtains the interval start time between the black start instruction at the current time and the black start instruction before the current time based on the rated release voltage correction instruction. The battery management unit obtains the standard charging time for full charging of the capacitor, calculates the charging difference ratio between the standard charging time and the interval start time, and corrects the rated release voltage based on the charging difference ratio. The battery management unit then adjusts the output power of the lithium battery based on the corrected rated release voltage.

3. The black start system of the flow battery energy storage system according to claim 1, characterized in that: A second temperature sensor is also provided in the heat exchange tube, which is used to measure local temperature change data in the heat exchange tube and send the local temperature change data to the battery management unit; The battery management unit is used to calculate the temperature difference between the local temperature change data at the current time and the real-time temperature data, and compare the temperature difference with the set temperature threshold. If the temperature difference is greater than or equal to the temperature threshold, a corresponding flow rate increase or flow rate reduction instruction is generated based on the temperature difference and the real-time flow rate in the heat exchange tube, and the flow rate increase or flow rate reduction instruction is sent to the heating mechanism or the cooling mechanism. If the temperature difference is less than the temperature threshold, a flow rate maintenance instruction is sent to the heating mechanism or the cooling mechanism.

4. A control method for a black start system of a flow battery energy storage system, characterized in that: The control method for a black start system of a flow battery energy storage system according to any one of claims 1 to 3 comprises the following steps: S1, judging the operating status of the flow battery module, obtaining whether the voltage value output by the AC / DC converter at the current time is greater than the standard value, if the voltage value is greater than the standard value, entering S3, if the voltage value is less than the standard value, entering S2; S2, the black start command is executed, the battery management unit starts the lithium battery, and the capacitor releases the stored energy; S2.

1. The battery management unit records the cumulative number of black start commands within the current time interval and compares the cumulative number with the set standard start value. If the cumulative number is greater than the standard start value, a rated release voltage correction command is sent to the battery management unit. If the cumulative number is less than the standard start value, the output power of the lithium battery is corrected based on the rated release voltage of the capacitor. S2.

2. At the same time, the lithium battery or capacitor supplies power to the electrolyte circulation unit and compares the real-time temperature data in the positive electrode electrolyte storage tank or the negative electrode electrolyte storage tank with the suitable operating temperature. If the real-time temperature data is greater than the suitable operating temperature, a cold source connection instruction is sent to the three-phase solenoid valve, and the liquid flow battery module begins to transmit current to the external circuit. If the real-time temperature data is less than or equal to the suitable operating temperature, a heat source connection instruction is sent to the three-phase solenoid valve, and the liquid flow battery module begins to transmit current to the external circuit. S3. The battery management unit obtains the current working instructions and adjusts the working status of the flow battery module and the lithium battery.

5. The control method for a black start system of a flow battery energy storage system according to claim 4, characterized in that: In S2.2, when the liquid flow battery module starts to transmit current to the external circuit, the battery management unit will record the continuous power generation time of the liquid flow battery module, and then compare the continuous power generation time with the set lithium battery charging time. If the continuous power generation time is greater than the lithium battery charging time, a charging instruction will be sent to the lithium battery. If the continuous power generation time is less than the lithium battery charging time, the process will be terminated.

6. The control method for a black start system of a flow battery energy storage system according to claim 5, characterized in that: When the lithium battery executes the charging instruction, the battery management unit is also used to compare the current energy storage of the lithium battery at the current time with the set limit value. If the current energy storage is greater than the limit value, the lithium battery charging is terminated. If the current energy storage is less than the limit value, the lithium battery charging is maintained.

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