All-vanadium redox flow battery for energy storage, energy storage system and use method of energy storage system

Abstract

The invention relates to the field of power generation, and discloses an all-vanadium redox flow battery for energy storage, the all-vanadium redox flow battery for energy storage comprises a plurality of electric piles, each electric pile comprises a positive electrode liquid storage tank, a negative electrode liquid storage tank and a battery pile, the battery pile is provided with a positive electrode, a negative electrode and an ionic membrane for separating the positive electrode and the negative electrode, and the ionic membrane divides the battery pile into a positive electrode area and a negative electrode area; the positive electrode area and the negative electrode area are respectively communicated with a positive electrode liquid storage tank and a negative electrode liquid storage tank through pipelines, and pumps are arranged on the pipelines; the electric pile further comprises a positive wire and a negative wire which are respectively connected with the positive electrode and the negative electrode; and a plurality of electric piles are connected through the positive wire and the negative wire to form the all-vanadium redox flow battery for energy storage. According to the all-vanadium redox flow battery for energy storage, redundant electric energy can be converted into chemical energy in the battery for storage, and the chemical energy can be converted into electric energy for external use when needed.

Description

Technical Field

[0001] The present invention relates to the field of power generation, and in particular to a microgrid comprising an all-vanadium liquid flow battery and a use method thereof. Background Art

[0002] The microgrid system is a new type of power system that is developing rapidly. It is a self-sufficient isolated grid system within a certain range. It can operate independently of the main grid and can also be connected to the main grid when necessary. The microgrid system generally generates electricity through generator sets for external use. Since the external demand for electricity changes, and the generator sets tend to generate electricity at a constant power, the external electricity demand will have an impact on the generator sets.

[0003] In normal production processes, the electricity demand is generally within the range of ±15% of the target value, while the load shock that the generator set can withstand is ±5%, which cannot meet the ±15% requirement. Therefore, the generator set needs to be equipped with an energy storage battery to absorb the excess electricity of the power plant and release the stored electricity when the power plant provides insufficient electricity.

[0004] The energy storage tanks currently used store electricity by converting it into thermal energy, and then convert thermal energy into electricity when it is needed to release the energy. Specifically, the energy storage tank absorbs the excess electricity of the power plant, uses an electric heater to convert the excess electricity of the thermal power plant into thermal energy, and releases the thermal energy into the pool. When the energy needs to be released outward, it generates steam by heating the liquid or directly exchanges heat, thereby driving the turbine to generate electricity. However, due to the energy loss of heat exchange, etc., the energy utilization efficiency of the energy storage tank is low. Therefore, once the load fluctuates, it will cause a lot of energy waste. Summary of the invention

[0005] In order to overcome the problem of certain randomness of test results in the prior art, the present invention provides an all-vanadium liquid flow battery for energy storage, an energy storage system and a method for using the energy storage system. The all-vanadium liquid flow battery for energy storage can convert excess electrical energy into chemical energy within the battery for storage, and convert the chemical energy into electrical energy for external use when needed.

[0006] In order to achieve the above-mentioned object, the present invention provides an all-vanadium liquid flow battery for energy storage, wherein the all-vanadium liquid flow battery for energy storage comprises a plurality of battery stacks, wherein the battery stack comprises a cathode liquid storage tank, a cathode liquid storage tank and a battery stack, wherein the battery stack is provided with a positive electrode, a negative electrode and an ion membrane for separating the positive electrode and the negative electrode, wherein the ion membrane divides the battery stack into a positive electrode region and a negative electrode region, wherein the positive electrode region and the negative electrode region are respectively connected to the cathode liquid storage tank and the cathode liquid storage tank through pipelines, wherein a pump is provided on the pipeline;

[0007] The battery stack further includes a positive electrode line and a negative electrode line, wherein the positive electrode line and the negative electrode line are connected to the positive electrode and the negative electrode respectively;

[0008] A plurality of the battery stacks are connected via the positive electrode line and the negative electrode line to form the all-vanadium liquid flow battery for energy storage.

[0009] Preferably, a plurality of the battery stacks are first connected in series and then in parallel, and the same number of the battery stacks are connected in series on each parallel branch of the all-vanadium liquid flow battery for energy storage.

[0010] Preferably, each parallel branch of the all-vanadium liquid flow battery for energy storage is provided with a current sensor and a voltage sensor.

[0011] The present invention also provides an energy storage system including the all-vanadium liquid flow battery for energy storage, the energy storage system includes an energy storage inverter, a safety and stability control scheduling device and a plurality of the all-vanadium liquid flow batteries for energy storage, the energy storage inverter is configured as a bidirectional inverter, the energy storage inverter is electrically connected to the all-vanadium liquid flow battery for energy storage, and the safety and stability control scheduling device controls the charging and discharging of the all-vanadium liquid flow battery for energy storage through the energy storage inverter.

[0012] Preferably, one of the energy storage converters is connected to one or more of the all-vanadium liquid flow batteries for energy storage.

[0013] Preferably, a plurality of all-vanadium liquid flow batteries for energy storage connected to the same energy storage converter are connected in parallel.

[0014] Preferably, a plurality of all-vanadium liquid flow batteries for energy storage connected to the same energy storage converter are connected in series.

[0015] The present invention also provides a method for using the energy storage system, the method comprising:

[0016] Step 1: The safety and stability control dispatching device monitors the power of the external power generation group and the power consumption group, and controls the energy storage converter to charge or discharge the all-vanadium liquid flow battery for energy storage according to the implemented power difference;

[0017] Step 2: The safety and stability control scheduling device is electrically connected to the current sensor and the voltage sensor to monitor the real-time power of multiple fuel cells;

[0018] Step three, the safety and stability control scheduling device is electrically connected to the pump, and according to the monitoring result of step two, the safety and stability control scheduling device controls the flow rate of the pump.

[0019] Preferably, the cathode liquid storage tank and the cathode liquid storage tank are respectively provided with temperature sensors, and the temperature sensors are electrically connected to the safety and stability control scheduling device.

[0020] Preferably, in step 2, the safety and stability control scheduling device controls the flow rate of the pump according to the values ​​of the ammeter and the voltmeter.

[0021] According to the above technical solution, an all-vanadium liquid flow battery for energy storage can be formed by connecting multiple battery stacks in series or in parallel. Preferably, an all-vanadium liquid flow battery for energy storage with greater power can be formed by first connecting the battery stacks in series and then in parallel.

[0022] Both the cathode liquid storage tank and the cathode liquid storage tank store electrolytes, which contain vanadium ions. During use, the charging or discharging of the battery stack is achieved through oxidation or reduction reactions of the vanadium ions.

[0023] A positive electrode and a negative electrode are provided in the battery stack. The positive electrode liquid storage tank and the negative electrode liquid storage tank can respectively input electrolyte into the positive electrode area and the negative electrode area through pumps arranged on the inflow pipeline so that the positive electrode and negative electrode electrolytes circulate inside the battery to achieve continuous charging and discharging reactions.

[0024] The pump transports the electrolyte from the storage tank to the battery stack to ensure that the electrolyte can circulate in the battery. This circulation can maintain the concentration of reactants (such as V2+ and V3+) at the positive and negative electrode positions, avoiding the consumption of reactants at the electrode positions affecting the charging or discharging power of the battery stack. By adjusting the flow rate of the pump, it can ensure that the electrolyte is continuously refreshed at the electrode reaction interface, and it can also promote the uniform distribution of the electrolyte during circulation, thereby reducing local overheating or local electrolyte depletion. At the same time, the pump can also promote electrochemical reactions. By forcing the electrolyte to circulate, the pump can enhance the efficiency of the contact between the electrolyte and the electrode, thereby improving the reaction rate and energy conversion efficiency of the battery.

[0025] The flow rate of the pump can be adjusted to suit the power requirements of the system during charging and discharging. During charging, a higher flow rate is usually required to ensure the rapid conversion of vanadium ions and the redox reaction; during discharge, the flow rate also needs to be properly controlled to optimize the current density and discharge efficiency.

[0026] Therefore, it can be seen that the energy storage active material in the positive and negative electrode areas of the battery stack - the electrolyte is stored in the electrolyte storage tank outside the battery. The electrolyte circulation pump and the inflow and outflow pipelines can realize the forced circulation of the electrolyte between the electrolyte storage cabinet and the battery stack. Regardless of whether the battery stack is in a charging or discharging working state, the electrolyte reserves determine the energy storage capacity of the battery stack.

[0027] In order to obtain more energy storage capacity, the all-vanadium liquid flow battery for energy storage includes multiple battery stacks. Therefore, the all-vanadium liquid flow battery for energy storage can be used to provide energy buffering for the isolated grid system. When the power consumption of the external electrical equipment is less than the power of the generator, the excess power at the generator end can be input into the all-vanadium liquid flow battery for energy storage and stored by the all-vanadium liquid flow battery for energy storage, which will not cause a large energy loss. When the power of the external electrical equipment is greater than the power of the generator, the all-vanadium liquid flow battery for energy storage can be discharged to supplement the insufficient power on the power generation side. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of an all-vanadium liquid flow battery for energy storage;

[0029] Figure 2 This is a circuit diagram of an all-vanadium liquid flow battery for energy storage;

[0030] Figure 3 It is a schematic diagram of the connection between an energy storage converter and an all-vanadium liquid flow battery for energy storage;

[0031] Figure 4 It is a schematic diagram of another energy storage converter connected to an all-vanadium liquid flow battery for energy storage;

[0032] Figure 5 This is a schematic diagram of the structure of a battery stack.

[0033] Description of Reference Numerals

[0034] 11 Battery stack 12 Cathode liquid storage tank

[0035] 13 Negative liquid storage tank 10 All-vanadium liquid flow battery for energy storage

[0036] 14 Inflow pipe 15 Outflow pipe

[0037] 21 Energy Storage Converter 16 Battery Stack

[0038] 17 positive electrode area 18 negative electrode area

[0039] 19 pumps 111 ion membrane DETAILED DESCRIPTION

[0040] In the present invention, unless otherwise stated, directional words such as "away from, up, down, sideways, both ends" generally refer to the orientation of the term in normal use, or are common names understood by those skilled in the art, and should not be regarded as limitations on the term.

[0041] See also Figure 1-2The all-vanadium liquid flow battery 10 for energy storage comprises a plurality of battery stacks 16, wherein the battery stack 16 comprises a cathode liquid storage tank 12, a cathode liquid storage tank 13 and a battery stack 11, wherein the battery stack 11 is provided with a positive electrode, a negative electrode and an ion membrane 111 for separating the positive electrode and the negative electrode, wherein the ion membrane 111 divides the battery stack 11 into a positive electrode region and a negative electrode region, wherein the positive electrode region and the negative electrode region are respectively connected to the cathode liquid storage tank 12 and the cathode liquid storage tank 13 through pipelines, and a pump is provided on the pipelines;

[0042] The battery stack 16 also includes a positive electrode line and a negative electrode line, and the positive electrode line and the negative electrode line are connected to the positive electrode and the negative electrode respectively;

[0043] A plurality of battery stacks 16 are connected by positive and negative lines to form an all-vanadium liquid flow battery 10 for energy storage.

[0044] By implementing the above technical solution, a full-vanadium liquid flow battery 10 for energy storage can be formed by connecting multiple battery stacks 16 in series or in parallel. Preferably, a full-vanadium liquid flow battery 10 for energy storage with a larger power can be formed by first connecting the battery stacks 16 in series and then in parallel.

[0045] The positive electrode liquid storage tank 12 and the negative electrode liquid storage tank 13 both store electrolytes, and the electrolytes both contain vanadium ions. During use, the charging or discharging of the battery stack 16 is achieved through oxidation or reduction reactions of the vanadium ions.

[0046] In actual use, the active electrode pair of the positive half-cell electrolyte is The active electrode pair of the negative half-cell electrolyte is V 3+ / V 2+ , and its electrode reaction is as follows.

[0047] Positive electrode reaction:

[0048] Negative electrode reaction:

[0049] Overall battery reaction:

[0050] When the battery is charging, the VO in the electrolyte in the positive electrode area 2+ Loss of electrons to form V in the electrolyte in the negative electrode region 3+ Get electrons to form V 2+ , electrons pass through the external circuit from the positive electrode to the negative electrode to form a current, H + Then, the charge is transferred from the positive electrode to the negative electrode through the ion membrane 111 to form a closed loop. The discharge process is the opposite.

[0051] like Figure 5As shown, a positive electrode and a negative electrode are provided in the battery stack 16, and the positive electrode liquid storage tank 12 and the negative electrode liquid storage tank 13 can respectively input electrolyte into the positive electrode area and the negative electrode area through a pump 19 provided on the inlet pipe 14 so that the positive electrode and negative electrode electrolytes circulate inside the battery to achieve continuous charge and discharge reactions.

[0052] Pump 19 transports the electrolyte from the storage tank to the battery stack 11 to ensure that the electrolyte can circulate in the battery. This circulation can maintain the concentration of positive and negative electrode reactants (such as V2+ and V3+) to prevent the consumption of reactants from affecting the charging or discharging power of the battery stack 16. By adjusting the flow rate of pump 19, the electrolyte can be evenly distributed in the battery stack 11, thereby reducing local overheating or local electrolyte depletion. At the same time, pump 19 can also promote electrochemical reactions. By forcing the electrolyte to circulate, pump 19 can enhance the efficiency of contact between the electrolyte and the electrode, thereby improving the reaction rate and energy conversion efficiency of the battery.

[0053] The flow rate of the pump 19 can be adjusted to adapt to the power demand of the system during the charging and discharging process. During charging, a higher flow rate is usually required to ensure the rapid conversion of vanadium ions and the redox reaction; and during discharging, the flow rate also needs to be properly controlled to optimize the current density and discharge efficiency.

[0054] Therefore, it can be seen that the energy storage active material in the positive and negative electrode regions of the battery stack 16 - the electrolyte is stored in an electrolyte storage tank outside the battery. The electrolyte circulation pump 19 and the inlet pipe 14 and the outlet pipe 15 can realize the forced circulation of the electrolyte between the electrolyte storage cabinet and the battery stack 11. Regardless of whether the battery stack 16 is in a charging working state or a discharging working state, the amount of electrolyte reserves determines the energy storage capacity of the battery stack 16.

[0055] In order to obtain more energy storage capacity, the all-vanadium liquid flow battery 10 for energy storage includes multiple battery stacks 16. Therefore, the all-vanadium liquid flow battery 10 for energy storage can be used to provide energy buffering for the isolated grid system. When the power consumption of the external electrical equipment is less than the power of the generator, the excess power at the generator end can be input into the all-vanadium liquid flow battery 10 for energy storage and stored by the all-vanadium liquid flow battery 10 for energy storage, without causing a large energy loss. When the power of the external electrical equipment is greater than the power of the generator, the all-vanadium liquid flow battery 10 for energy storage can be discharged to supplement the insufficient power on the power generation side.

[0056] Preferably, the inflow pipe 14 is connected to the bottom of the battery stack 16, close to the position of the electrode, so that the supplemented electrolyte can be quickly transported to the electrode position to participate in a new electrochemical reaction, and then the electrolyte that does not participate in the reaction moves upward under the guidance of the electrode and the pressure of the pump, and flows out from the upper outflow pipe 15. Preferably, the outflow pipe 15 is arranged at the upper part of the battery stack 11, away from the position of the electrode, so that the newly supplemented electrolyte can obtain sufficient flow in the battery stack 11, thereby achieving the effect of stirring and mixing the electrolyte in the battery stack 11.

[0057] In this embodiment, preferably, a plurality of battery stacks 16 are first connected in series and then in parallel, and the same number of battery stacks 16 are connected in series on each parallel branch of the all-vanadium liquid flow battery 10 for energy storage.

[0058] A plurality of series-connected battery stacks 16 can control the voltage of the all-vanadium liquid flow battery 10 for energy storage, while a plurality of parallel-connected branches can control the current of the all-vanadium liquid flow battery 10 for energy storage. This design enables the all-vanadium liquid flow battery 10 for energy storage to have a better power combination.

[0059] In this embodiment, preferably, each parallel branch of the all-vanadium liquid flow battery 10 for energy storage is provided with a current sensor and a voltage sensor.

[0060] The battery stacks 16 on the same parallel branch are connected in series. Therefore, the voltages of multiple battery stacks 16 on the same parallel branch may be different, but the currents are the same. Therefore, only one ammeter is needed on the same parallel branch, and a voltmeter is needed for each battery stack 16. The real-time power of charging or discharging in the branch is detected by the cooperation of the ammeter and the voltmeter.

[0061] Preferably, by adjusting the pumps 19 of multiple battery stacks 16 on the same branch, the battery stacks 16 on the same branch can be charged or discharged synchronously, so as to improve the use efficiency of the all-vanadium liquid flow battery 10 for energy storage.

[0062] In this embodiment, preferably, both the positive electrode region and the negative electrode region are provided with an inlet pipe 14 and an outlet pipe 15, and the positive electrode region and the negative electrode region are respectively connected to the positive electrode liquid storage tank 12 and the negative electrode liquid storage tank 13 through the inlet pipe 14 and the outlet pipe 15 for electrolyte circulation.

[0063] See also Figure 3-4The energy storage system comprising an all-vanadium liquid flow battery 10 for energy storage comprises an energy storage converter 21, a safety and stability control scheduling device and a plurality of all-vanadium liquid flow batteries 10 for energy storage. The energy storage converter 21 is configured as a bidirectional converter. The energy storage converter 21 is electrically connected to the all-vanadium liquid flow battery 10 for energy storage. The safety and stability control scheduling device controls the charging and discharging of the all-vanadium liquid flow battery 10 for energy storage through the energy storage converter 21.

[0064] Through the implementation of the above technical solution, the safe and stable dispatching device can control the energy storage converter 21 to charge the all-vanadium liquid flow battery 10 for energy storage, or control the all-vanadium liquid flow battery 10 for energy storage to discharge outward according to the needs of the external environment. The energy storage converter 21 is set as a bidirectional converter, which can realize the flow of energy in two directions, and can convert DC power into AC power, and also convert AC power into DC power. It is only necessary to control the on and off states of the switch elements to adjust the direction of the current and realize effective energy management.

[0065] When the all-vanadium liquid flow battery 10 for energy storage needs to be charged, the energy storage converter 21 is in rectification mode, which can convert AC power into DC power, and the all-vanadium liquid flow battery 10 for energy storage stores the DC power in the all-vanadium liquid flow battery 10 for energy storage. When the all-vanadium liquid flow battery 10 for energy storage needs to be discharged, the energy storage converter 21 is in inversion mode, which can convert the DC power stored in the all-vanadium liquid flow battery 10 for energy storage into AC power and transmit it to the external network.

[0066] Since the power fluctuation of the external network varies in size, the energy storage converter 21 can be set so that the safety and stability control dispatching device can determine how many energy storage converters 21 to start according to the power fluctuation of the external network. When the power fluctuation is not large, starting an energy storage converter 21 to charge or discharge the all-vanadium liquid flow battery 10 for energy storage connected to the energy storage converter 21 can achieve power balance to the external network; when the power fluctuation of the external environment is large, it is necessary to start multiple energy storage converters 21 so that more all-vanadium liquid flow batteries 10 for energy storage can participate in the power balance work to achieve a rapid response to the power change of the external environment.

[0067] The safety and stability control dispatching device collects various signals through sensors, and the signals collected by the sensors are transmitted to the safety and stability control dispatching device, which then completes the logic control. The data collection of the voltage of each battery stack 16 and the current of each parallel branch is realized to facilitate the management of the energy storage system.

[0068] For good power management, the safe and stable dispatching device balances and adjusts by collecting current and voltage data, calculating and controlling the start and stop of pumps, the opening and closing of electric valves, the start and stop of refrigerators, and the migration of electrolyte water, while monitoring the status of the entire energy storage system, including lighting control, exhaust start and stop, fire control, etc.

[0069] In this embodiment, preferably, one energy storage converter 21 is connected to one or more all-vanadium redox flow batteries 10 for energy storage.

[0070] According to the actual situation of the external environment, one energy storage converter 21 can be connected to one all-vanadium liquid flow battery 10 for energy storage. Since each energy storage converter 21 is only connected to one all-vanadium liquid flow battery 10 for energy storage, the safety and stability control dispatching device can start multiple energy storage converters 21 in sequence according to the actual situation to meet the adaptation to external power changes. The energy storage system under this scheme has high sensitivity to external power regulation.

[0071] When one energy storage converter 21 is connected to multiple all-vanadium liquid flow batteries 10 for energy storage, since the safety and stability control scheduling device can start multiple all-vanadium liquid flow batteries 10 at one time, the safety and stability control scheduling device has a fast adaptive response speed to external power changes.

[0072] In this embodiment, preferably, a plurality of all-vanadium redox flow batteries 10 for energy storage connected to the same energy storage converter 21 are connected in parallel.

[0073] When the all-vanadium liquid flow batteries 10 for energy storage connected to the same energy storage converter 21 are connected in parallel, the energy capacity of the system can be easily increased by connecting in parallel. Moreover, if a certain all-vanadium liquid flow battery 10 for energy storage fails, other all-vanadium liquid flow batteries 10 for energy storage can still work normally, thereby improving the overall reliability of the system.

[0074] When the all-vanadium liquid flow batteries 10 for energy storage are connected in parallel, they can meet the current requirements in a larger range, and thus can better adapt to different load requirements and provide the required current and power.

[0075] By adopting the parallel connection of the all-vanadium liquid flow batteries 10 for energy storage, since each all-vanadium liquid flow battery 10 for energy storage can operate independently, the process of maintaining and replacing the all-vanadium liquid flow batteries 10 for energy storage is relatively simple and will not affect the entire system.

[0076] In this embodiment, preferably, a plurality of all-vanadium redox flow batteries 10 for energy storage connected to the same energy storage converter 21 are connected in series.

[0077] In the series connection of the vanadium redox flow batteries 10 for energy storage, the positive electrode of each vanadium redox flow battery 10 for energy storage is connected to the negative electrode of the next vanadium redox flow battery 10 for energy storage. In this way, the total voltage of the system is equal to the sum of the voltages of each unit, while the current remains unchanged.

[0078] When the all-vanadium liquid flow batteries 10 for energy storage are connected in series, the electrolyte circulation of each battery cell is independent, ensuring that they can carry out the charging and discharging process normally.

[0079] By connecting the all-vanadium liquid flow batteries 10 for energy storage in series, the required higher voltage can be achieved to meet the needs of high-voltage applications, such as being connected to a power grid or other high-voltage equipment. At the same time, the all-vanadium liquid flow batteries 10 for energy storage in series can increase the overall energy density of the system, allowing more energy to be stored in a limited space.

[0080] Preferably, when the energy storage converter 21 is connected to a plurality of all-vanadium liquid flow batteries 10 for energy storage, the all-vanadium liquid flow batteries 10 for energy storage can be connected in series first, and then the all-vanadium liquid flow batteries 10 for energy storage connected in series can be connected in parallel, and each parallel branch has the same number of all-vanadium liquid flow batteries 10 for energy storage connected in series. In this way, different voltage and power requirements can be met as needed.

[0081] A method for using an energy storage system, the method comprising:

[0082] Step 1: The safety and stability control dispatching device monitors the power of the external generator set and the power-consuming equipment, and controls the energy storage converter 21 to charge or discharge the all-vanadium liquid flow battery 10 for energy storage according to the implemented power difference;

[0083] Step 2: The safety and stability control dispatching device is electrically connected to the current sensor and the voltage sensor to monitor the real-time power of the multiple battery stacks 16;

[0084] Step three, the safety and stability control dispatching device is electrically connected to the pump, and according to the monitoring result of step two, the safety and stability control dispatching device controls the flow of the pump.

[0085] Through the implementation of the above technical solution, the generator set is provided with a sensor for detecting the implemented power, and the sensor outputs a signal to the safety and stability control scheduling device. The safety and stability control scheduling device collects the electric power signal of the generator set for comparison with the power used by the electrical equipment. If the generated power is balanced with the used power, the safety and stability control scheduling device will not adjust the system. If the comparison finds that the power on the power generation side is not equal to the power on the power consumption side, the safety and stability control scheduling device needs to regulate the system.

[0086] In one embodiment, the safety and stability control scheduling device compares the difference rate between the power on the power consumption side and the power on the power generation side. If the difference between the power on the power consumption side and the power on the power generation side does not exceed ±5% of the power on the power generation side, the safety and stability control scheduling device believes that the load fluctuation is not large, and the parameters of the generator set can be adjusted so that the function of the power generation side can match the power on the power consumption side.

[0087] The engine unit itself has a certain power regulation function. In one embodiment, the engine unit is set as a steam generator. The real-time power of the generator unit can be controlled by adjusting the steam pressure and flow of the steam turbine, but the adjustment range is only ±5%. Therefore, when the electric power fluctuation range on the power consumption side is within the range of ±5%, the safe and stable control scheduling device can achieve electric load balance by controlling the control parameters of the generator itself.

[0088] However, if the difference between the power on the power consumption side and the power on the power generation side exceeds ±5% of the power on the power generation side, the generator cannot adapt to this electric load fluctuation, and the safety and stability control dispatching device needs to take other control measures. Specifically, if the power on the power consumption side is greater than the power on the power generation side, the safety and stability control dispatching device needs to immediately control the energy storage converter 21 to put the all-vanadium liquid flow battery 10 for energy storage in a discharge state, and release electric energy through the all-vanadium liquid flow battery 10 for energy storage to make up for the power shortage on the power generation side, so as to maintain the balance of the electric load of the isolated grid. If the power on the power generation side is greater than the power on the power consumption side, the energy storage converter 21 is started to charge the all-vanadium liquid flow battery 10 for energy storage, and the excess electric energy is stored in the all-vanadium liquid flow battery 10 for energy storage, so as to balance the power on the power generation side and the power consumption side.

[0089] A plurality of energy storage inverters 21 are provided. During actual use, the safety and stability control scheduling device determines the number of energy storage inverters 21 that need to be started according to the difference between the power consumption side and the power generation side, and immediately starts the energy storage inverter 21 to quickly respond to the power load fluctuation of the isolated grid.

[0090] When the power fluctuation on the power consumption side is not greater than ±5%, that is, the difference between the power consumption side and the power generation side does not exceed ±5% of the power generation side, the system can be considered to be in normal operation. At this time, the safe and stable control dispatching device can adapt to the power fluctuation on the power consumption side by adjusting the control parameters of the generator set.

[0091] The energy storage system is a working system that converts electrical energy into chemical energy for storage through electrochemical reactions. When needed, the energy storage system can convert chemical energy into electrical energy for the load, and when the power on the power generation side is insufficient, the energy storage system can control the discharge of the all-vanadium liquid flow battery 10 used for energy storage to provide electrical energy for the power consumption side.

[0092] The capacity and power of the all-vanadium liquid flow battery 10 for energy storage are decoupled, and it has the advantages of high safety, flexible duration, convenient expansion, high resource self-sufficiency rate, and long cycle life. The energy storage system is relatively flexible and can cope with the input of various energy sources and the output of loads; secondly, the all-vanadium liquid flow battery is an aqueous electrolyte, and the battery energy storage system has a fast response speed and can quickly respond to changes in the power grid to maintain the stability of the power grid; the system can provide backup power, and when the power grid fails, it can quickly provide backup power to ensure the stable operation of the power grid.

[0093] In this embodiment, preferably, the generator set is provided with a load meter, the busbar of the electrical equipment is provided with a current transformer and a voltage transformer, the load meter measures the power P1 of the generator set, and the current transformer and the voltage transformer measure the power P2 of the electrical equipment;

[0094] The safety and stability control dispatching device is electrically connected to the load meter, current transformer and voltage transformer. The safety and stability control dispatching device compares the fluctuation △P of the power P1 of the generator set and the power P2 of the electrical equipment in real time, △P=(P2-P1).

[0095] In order to protect the generator set as much as possible, the safety and stability control dispatching device needs to monitor the values ​​of P1 and P2 in real time, and adjust the power on the power consumption side or the power generation side according to the value of △P.

[0096] In this embodiment, preferably, in step 1, if -5%≤ΔP / P1≤5%, the energy storage converter 21 is not started.

[0097] If -5%≤△P / P1≤5%, the safety and stability control dispatching device can adjust the control parameters of the generator set to meet the requirements of electrical load balance.

[0098] In step 1, if the amplitude of the power fluctuation is between ±5% and ±15%, the safety and stability control dispatching device controls the energy storage converter 21 to start charging or discharging the all-vanadium liquid flow battery 10 for energy storage.

[0099] When the power reduction of the electrical equipment in the isolated grid exceeds 5%, the generator set cannot achieve automatic load balancing. At this time, the safety and stability dispatching device will start the energy storage converter 21 to charge the all-vanadium liquid flow battery 10 for energy storage. According to the actual power reduction value, the corresponding number of energy storage converters 21 are started so that the power fluctuation of the isolated grid can be quickly responded to, so as to achieve a balance between the power on the power side and the power on the power generation side.

[0100] Similarly, if the power increase of the electric equipment in the isolated grid exceeds 5%, the safety and stability dispatching device will start the energy storage converter 21 to discharge the energy storage all-vanadium liquid flow battery 10 to the electric equipment. According to the actual value of the power increase, the corresponding number of energy storage converters 21 are started so that the power fluctuation of the isolated grid can be quickly responded to, so as to achieve a balance between the power consumption side and the power generation side.

[0101] In this embodiment, preferably, in step 2, if the power fluctuation is greater than 15%, the safety and stability control scheduling device controls the energy storage converter 21 to start.

[0102] When the power of the electrical equipment is suddenly reduced and the power reduction is greater than 15%, the safety and stability control dispatching device needs to quickly start the corresponding number of energy storage converters 21 and reduce the load on the power consumption side and the power generation side after the electric load of the isolated grid is balanced.

[0103] Specifically, when the isolated grid power load is balanced, the safety and stability control dispatching device shuts down a certain number of energy storage inverters 21, and correspondingly shuts down the power generating sets with the same power value, and performs real-time detection of the power on the isolated grid power generation side and the power consumption side, and adjusts in real time according to the detection results until the isolated grid power load is balanced.

[0104] Preferably, in order to avoid excessive load unloading at one time causing large power fluctuations in the isolated grid, a safety and stability control dispatching device can be set to perform load unloading operations in multiple times according to the actual load conditions. Specifically, after a certain number of energy storage converters 21 are closed for the first time to unload the load, the power on the power generation side and the power consumption side is detected. After the load of the isolated grid is balanced, the safety and stability control dispatching device closes a certain number of energy storage converters 21 again, and correspondingly closes the generator sets with the same power value. Then, the power on the power generation side and the power consumption side of the isolated grid is detected. After the power balance between the power generation side and the power consumption side is detected, the next load unloading operation can be performed. Until all energy storage converters 21 are closed.

[0105] Similarly, when the power of an electrical equipment suddenly increases, and the power increase is greater than 15%, the safety and stability control scheduling device needs to quickly start a corresponding number of energy storage inverters 21, and start a considerable number of all-vanadium liquid flow batteries 10 for energy storage to discharge to the electrical equipment to make up for the power shortage on the power generation side. Subsequently, the staff determines whether the increased power is a temporary increase in power or power for normal production use, so that the safety and stability control scheduling device can decide whether it is necessary to start a new generator set to adapt to the power changes of the electrical equipment as soon as possible.

[0106] If the increased power is a temporary increase in power, that is, the power on the power consumption side will be restored soon, then the energy storage converter 21 will control the all-vanadium liquid flow battery 10 used for energy storage to discharge to cope with the power fluctuation.

[0107] If the increased power is continuous power, that is, a new load device is put into production on the power consumption side, then the safety and stability control dispatching device will control the start-up of a new generator set to cope with the power change on the power consumption side. In this embodiment, preferably, in step 1, the safety and stability control dispatching device records the power P2 and current I2 of the power consumption equipment, and the safety and stability control dispatching device is also provided with a monitoring period T;

[0108] In addition to real-time monitoring of the power of electrical equipment and generators to achieve power regulation of the isolated grid, power regulation of the isolated grid can also be achieved by detecting power fluctuations on the power consumption side.

[0109] The power of the electrical equipment at any time t is P2t, and the current is I2t. At time t+T after one monitoring cycle, the power of the electrical equipment is P2(t+T), and the current is I2(t+T). The safety and stability control scheduling device calculates the power fluctuation P2(t+T)-P2t and the current fluctuation I2(t+T)-I2t, and compares them with the power fluctuation design value △Ps and the current fluctuation design value △Is.

[0110] Since the generator set has a response time to the power fluctuation of the electrical equipment, some sudden fluctuations of very short duration, although with large amplitude, will not affect the generator set due to their short duration. Based on this characteristic, a monitoring period T is set in the safety and stability control dispatching device. The monitoring period T is less than the response time of the system, so that the control sensitivity of the safety and stability control dispatching device is more sensitive than the generator set, and thus it can effectively block the impact of power fluctuations on the generator set. Therefore, this method can avoid the problem of the safety and stability control dispatching device frequently needing to control the isolated grid system, and can effectively reduce the control complexity of the safety and stability control dispatching device while ensuring safety and effectiveness.

[0111] Usually the response time of a generator set is not less than 1 second, therefore, the monitoring period T needs to be less than 1 second, preferably, T is less than 500 ms, taking T=200 ms as an example.

[0112] At the beginning and end of a monitoring cycle, the power change on the power consumption side is P2(t+T)-P2t. If the power change does not exceed the power fluctuation design value △Ps, the power fluctuation design value △Ps is 0.05P2t. At this time, the safety and stability control dispatching device achieves power balance of the isolated grid system by adjusting the control parameters of the generator set.

[0113] If the power variation exceeds ΔPs, the safe and stable control dispatching device needs to start the energy storage converter 21, and the control method is the same as the control principle for implementing the control.

[0114] In addition to setting the monitoring period T to reduce the control complexity of the safety and stability control dispatching device, the signal collection period of the safety and stability control dispatching device can also be controlled. The signal collection period can be less than the monitoring period T. A higher signal collection frequency can improve the reliability of monitoring, and a lower signal collection frequency can effectively reduce the control complexity of the safety and stability control dispatching device. Therefore, by setting a suitable signal collection frequency and monitoring period T in the safety and stability control dispatching device, the two generator sets can be effectively coordinated and more conveniently adapted to various usage environments.

[0115] In this embodiment, preferably, in step one, the electrical equipment is configured to be able to propose a load increase plan to the safety and stability control scheduling device, and the load increase plan at least includes: execution time and planned increase in power P3.

[0116] The safety and stability control scheduling device shown increases the power generation of the generator set according to the specific value of P3, and starts the energy storage inverter 21 equivalent to P3 at the same time. The newly added electric energy of the generator set is charged to the all-vanadium liquid flow battery 10 for energy storage via the energy storage inverter 21. After the generator set is successfully started, the energy storage inverter 21 is turned off, and the load increase plan is executed at the same time. At this time, the power on the power generation side and the power consumption side can still be balanced.

[0117] Preferably, in order to ensure the smooth operation of the isolated grid system, the electrical equipment may be started in batches, and some energy storage converters 21 may be correspondingly shut down until all energy storage converters 21 are shut down and the system enters the normal use stage.

[0118] In this embodiment, preferably, the cathode liquid storage tank 12 and the cathode liquid storage tank 13 are respectively provided with temperature sensors, and the temperature sensors are electrically connected to the safety and stability control scheduling device.

[0119] The temperature of the electrode liquid affects the stability of the electrolyte, so the safety and stability scheduling device also needs to monitor the temperature of the electrolyte in the positive electrode liquid storage tank 12 and the negative electrode liquid storage tank 13. Usually, the temperature of the electrolyte is set at 0-50°C, and preferably, the temperature of the electrolyte needs to be maintained at 20-40°C. In order to ensure the stable operation of the electrolyte, the energy storage system is also provided with a cooling device for cooling the electrolyte to ensure that the temperature of the electrolyte is always at the optimal working temperature during the charging and discharging process.

[0120] As the temperature of the electrolyte increases, the thermal motion of the ions accelerates, the frequency and thermal motion of the positive and negative electrolytes passing through the ion membrane 111 accelerate, and the amount of vanadium ions that are connected to each other increases. The voltage efficiency of the battery increases with the increase of temperature, and the lower the temperature, the more obvious the change trend. The main reason is that as the operating temperature increases, the viscosity decreases, the electrolyte flow increases, the electrolyte renewal rate on the electrode reaction interface accelerates, the concentration polarization in the battery is reduced, the ion conduction speed is accelerated, and the voltage efficiency is significantly improved; however, as the temperature further increases, although the flow rate is further increased, the renewal rate of the electrolyte in the battery stack is sufficient, so the voltage efficiency is partially improved but the improvement is not obvious. Therefore, excessively high temperatures will not bring about significant improvements in the performance of all-vanadium liquid flow batteries used for energy storage.

[0121] The temperature of the electrolyte not only affects the electrolyte renewal rate at the electrode reaction interface, but also affects the stability of the electrolyte. The volume of the electrolyte and the vanadium ion concentration determine the energy storage capacity of the all-vanadium liquid flow battery 10 for energy storage. The electrolyte of the all-vanadium liquid flow battery 10 for energy storage uses vanadium ions of different valence states as active substances and sulfuric acid aqueous solution as supporting electrolyte. Generally, in sulfuric acid supporting electrolyte, V 2+ 、V 3+ and V 4+ The solubility of ions increases with increasing temperature or decreasing sulfuric acid concentration. 5+ The solubility of vanadium ions shows the opposite trend. Therefore, the main reason for the low solubility of vanadium ions is that V 2+ 、V 3+ and V 4+ Ions are easy to precipitate at low temperatures and V 5+ Ions are easily precipitated into V at high temperatures 2 O 5 .

[0122] Therefore, the safety and stability scheduling device controls the temperature of the battery to be no higher than 50 degrees, preferably, no higher than 40 degrees.

[0123] In this embodiment, preferably, in step 2, the safety and stability control scheduling device controls the flow rate of the pump 19 according to the values ​​of the voltmeter and the ammeter.

[0124] Different energy storage inverters 21 control one or more all-vanadium liquid flow batteries 10 for energy storage, and each all-vanadium liquid flow battery 10 for energy storage contains one or more ammeters. Corresponding to the same ammeter, multiple battery stacks 16 are arranged, and each battery stack 16 corresponds to a voltmeter. Therefore, there are multiple battery stacks 16 corresponding to the same energy storage inverter 21. The safety and stable control scheduling device can identify whether the multiple battery stacks 16 connected to the same energy storage inverter 21 are working synchronously by monitoring the ammeters and voltmeters corresponding to the multiple battery stacks 16, that is, whether the multiple battery stacks 16 are charged and discharged with the power they want to pass through.

[0125] Specifically, when the all-vanadium liquid flow battery 10 for energy storage is in a charging state, the safety and stability control scheduling device checks whether the ammeter values ​​of multiple parallel branches connected to the same energy storage inverter 21 are the same. If the ammeter of one or more branches shows a low value, the safety and stability control scheduling device will detect the values ​​of each voltmeter in the branch. For the battery stack 16 with a lower voltage value, the flow rate of the pump 19 of the battery stack 16 can be increased to increase the renewal speed of the electrolyte at the electrode reaction interface, thereby increasing the electrochemical reaction speed of the battery stack 16 and synchronizing it with other battery stacks 16 as soon as possible.

[0126] Similarly, when the all-vanadium liquid flow battery 10 for energy storage is in a discharging state, the safety and stability control scheduling device checks whether the ammeter values ​​of multiple parallel branches connected to the same energy storage inverter 21 are the same. If the ammeter of one or more branches shows a low value, the safety and stability control scheduling device will detect the values ​​of each voltmeter in the branch. For the battery stack 16 with a higher voltage value, the flow rate of the pump 19 of the battery stack 16 can be increased to increase the renewal speed of the electrolyte at the electrode reaction interface, thereby increasing the electrochemical reaction speed of the battery stack 16 and synchronizing it with other battery stacks 16 as soon as possible.

[0127] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0128] 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 invention will not further describe various possible combinations.

[0129] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. An all-vanadium liquid flow battery (10) for energy storage, characterized in that: The all-vanadium liquid flow battery (10) for energy storage comprises a plurality of battery stacks (16), wherein the battery stack (16) comprises a cathode liquid storage tank (12), a cathode liquid storage tank (13) and a battery stack (11), wherein the battery stack (11) is provided with a positive electrode, a negative electrode and an ion membrane (111) for separating the positive electrode and the negative electrode, wherein the ion membrane (111) divides the battery stack (11) into a positive electrode region and a negative electrode region, wherein the positive electrode region and the negative electrode region are respectively connected to the cathode liquid storage tank (12) and the cathode liquid storage tank (13) via pipelines, wherein a pump is provided on the pipelines; The battery stack (16) further comprises a positive electrode line and a negative electrode line, wherein the positive electrode line and the negative electrode line are connected to the positive electrode and the negative electrode respectively; A plurality of the battery stacks (16) are connected via the positive electrode line and the negative electrode line to form the all-vanadium liquid flow battery (10) for energy storage.

2. The all-vanadium liquid flow battery (10) for energy storage according to claim 1, characterized in that: The plurality of battery stacks (16) are first connected in series and then in parallel, and each parallel branch of the all-vanadium liquid flow battery (10) for energy storage has the same number of battery stacks (16) connected in series.

3. The all-vanadium liquid flow battery (10) for energy storage according to claim 2, characterized in that: Each parallel branch of the all-vanadium liquid flow battery (10) for energy storage is provided with a current sensor and a voltage sensor.

4. An energy storage system comprising the all-vanadium liquid flow battery (10) for energy storage according to claim 3, characterized in that: The energy storage system comprises an energy storage converter (21), a safety and stability control dispatching device and a plurality of all-vanadium liquid flow batteries (10) for energy storage, wherein the energy storage converter (21) is configured as a bidirectional converter, the energy storage converter (21) is electrically connected to the all-vanadium liquid flow batteries (10) for energy storage, and the safety and stability control dispatching device controls the all-vanadium liquid flow batteries (10) for energy storage to charge and discharge through the energy storage converter (21).

5. An energy storage system according to claim 4, characterized in that: One of the energy storage converters (21) is connected to one or more of the energy storage all-vanadium liquid flow batteries (10).

6. An energy storage system according to claim 5, characterized in that: A plurality of all-vanadium liquid flow batteries (10) for energy storage connected to the same energy storage converter (21) are connected in parallel.

7. An energy storage system according to claim 5, characterized in that: A plurality of all-vanadium liquid flow batteries (10) for energy storage connected to the same energy storage converter (21) are connected in series.

8. A method for using the energy storage system according to any one of claims 4 to 7, characterized in that: The method of use includes: Step 1: the safety and stability control dispatching device monitors the power of the external power generation group and the power consumption group, and controls the energy storage converter (21) to charge or discharge the all-vanadium liquid flow battery (10) for energy storage according to the implemented power difference; Step 2: the safety and stability control scheduling device is electrically connected to the current sensor and the voltage sensor to monitor the real-time power of multiple battery stacks (16); Step three, the safety and stability control scheduling device is electrically connected to the pump, and according to the monitoring result of step two, the safety and stability control scheduling device controls the flow rate of the pump.

9. A method of use according to claim 8, characterized in that: The cathode liquid storage tank (12) and the cathode liquid storage tank (13) are respectively provided with temperature sensors, and the temperature sensors are electrically connected to the safety and stability control scheduling device.

10. A method of use according to claim 8, characterized in that: In step 2, the safety and stability control scheduling device controls the flow rate of the pump (19) according to the values ​​of the ammeter and the voltmeter.

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