Patent Publication Number: US-2023138926-A1

Title: Distributed large-scale system of all-vanadium redox flow battery

Description:
RELATED APPLICATIONS 
     This application claims priority to and the benefit of Chinese Patent Application No. 202111288951.X filed on Nov. 2, 2021, the disclosure of which is expressly incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The application relates to the technical field of battery system manufacturing and application, in particular to a distributed large-scale system of an all-vanadium redox flow battery. 
     BACKGROUND 
     The vanadium redox flow battery is a redox battery with vanadium substances in a circulating flow liquid state, stores electric energy in sulfuric acid electrolyte of vanadium ions with different valence states in a chemical energy mode, and is a new-generation environment-friendly energy battery. 
     In the application process of the all-vanadium redox flow battery, the all-vanadium redox flow battery needs to supply power to a plurality of electric energy load points. When the all-vanadium redox flow battery is in a discharging state, an electric energy load point of the all-vanadium redox flow battery is electrically connected with an external load to provide required electric energy for the load; when the all-vanadium redox flow battery is in a charging state, the electric energy access point of the all-vanadium redox flow battery is electrically connected with the power supply system, so that the electric energy is stored. 
     In view of the above related technologies, the inventor thinks that when the all-vanadium redox flow battery needs to be connected to a plurality of external loads or power supply systems, situations may occur in which the power supply requirement is not met or the storage capacity is insufficient; in addition, when the external load and the power supply system are far away from the all-vanadium redox flow battery, the reaction rate of the electrolyte of the all-vanadium redox flow battery is affected, so that the power requirements of a plurality of distributed external loads or power supply systems cannot be met. 
     SUMMARY 
     In summary, the present application includes at least one of the following beneficial technical effects: 
     1. the main electrical energy storage center is connected with the power distribution subsystem through a pipeline, so that the traditional cable transportation electric energy can be converted into electrolyte transportation in the pipeline, the safety performance is improved, the power supply problem in an area and the high-power energy storage requirement are effectively relieved, when the all-vanadium redox flow battery is applied in a large scale, a redox flow DC power grid can be provided, the transmission power loss is reduced, the power support is rapidly carried out, and the secondary energy storage capacity can be set according to the power requirement of the power distribution subsystem; 
     2. in the process of charging and discharging of the all-vanadium redox flow battery, because some battery stacks do not participate in reaction and some battery stacks always react, some soc state deviation is generated, the main reference battery is connected with the main electrical energy storage center in parallel, the sub reference battery is connected with the sub electric energy storage center in parallel, the positive electrode and the negative electrode of the main reference battery and the positive electrode and the negative electrode of the sub reference battery are connected into the BMS subsystem, so that the soc states of the main electrical energy storage center and the sub electric energy storage center can be monitored in real time, and the soc balance is timely carried out on the main electrical energy storage center and the sub electric energy storage center according to monitored data. 
     Additional aspects and advantages will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic structural diagram of a distributed large-scale system embodying an all-vanadium redox flow battery in an embodiment of the present application. 
         FIG.  2    is a block diagram of a power distribution subsystem embodied in an embodiment of the present application. 
     
    
    
     DETAILED DESCRIPTION 
     In order to meet the power increase and decrease requirements of a plurality of distributed external loads or power supply systems, the application provides a distributed large-scale system of all-vanadium redox flow batteries. 
     The distributed large-scale system for the all-vanadium redox flow battery adopts the following technical scheme: 
     a distributed large-scale system of an all-vanadium redox flow battery comprises a main electrical energy storage center, a plurality of power distribution subsystems and a control subsystem; 
     for any power distribution subsystem, if the power of the power distribution subsystem does not meet a preset power requirement and/or the distance between the power distribution subsystem and the main electrical energy storage center exceeds a preset distance, a sub electric energy storage center connected with the main electrical energy storage center is arranged in the power distribution subsystem; 
     the power distribution subsystem comprises an electric energy load point and/or an electric energy access point; 
     the main electrical energy storage center and the plurality of power distribution subsystems are electrically connected with the control subsystem respectively. 
     By adopting the technical scheme, when the power distribution subsystem is far away from the main electrical energy storage center and/or does not meet the preset power requirement of the power distribution subsystem, the sub-electric energy storage center is matched with the main electrical energy storage center, the control subsystem dispatches the electrolyte of the main electrical energy storage center to the sub-electric energy storage center, so that the electrolyte of the main electrical energy storage center enters the sub-electric energy storage center, the electrolyte of the sub-electric energy storage center is balanced, and the power requirement of a plurality of external loads or power supply systems is met. 
     Optionally, the power distribution subsystem further includes a battery stack, a PCS subsystem and a control module, wherein an input end of the PCS subsystem is electrically connected to the battery stack, an output end of the PCS subsystem is electrically connected to the electric energy load point and/or the electric energy access point, the control module is electrically connected to the control subsystem and the battery stack, respectively, and the battery stack is connected to the main electrical energy storage center through a pipe; 
     when a sub electric energy storage center is arranged in the power distribution subsystem, the battery stack is also connected with the sub electric energy storage center through a pipeline; 
     the control module is electrically connected with the sub electrical energy storage center. 
     By adopting the technical scheme, the positive electrolyte and the negative electrolyte react in the battery stack to generate direct current, and the direct current is converted into alternating current through the PCS subsystem and is incorporated into a power grid so as to meet the power requirement of the power distribution subsystem; the control module can collect the direct current voltage output by the battery stack and control the flow rate of the electrolyte according to the collected direct current voltage, so that the reaction rate of the electrolyte in the battery stack is controlled, and the output power is flexibly controlled. 
     Optionally, the main electrical energy storage center includes a main anode electrolyte tank and a main cathode electrolyte tank; the main anode electrolyte tank and the power distribution subsystem are connected through a pipeline to form a main anode circulation pipeline, and the main cathode electrolyte tank and the power distribution subsystem are connected through a pipeline to form a main cathode circulation pipeline. 
     Through adopting above-mentioned technical scheme, through setting up main positive circulation pipeline and main negative pole circulation pipeline, can part anodal electrolyte and negative pole electrolyte, the two non-contact each other gets into the two poles of the earth of battery stack respectively to, can make anodal electrolyte and negative pole electrolyte recycle, reduce the wasting of resources. 
     Optionally, a main reference battery is connected in parallel between the main anode circulation pipeline and the main cathode circulation pipeline, the main reference battery includes a second anode reaction region and a second cathode reaction region, and the second anode reaction region is connected with the main anode electrolyte tank through a pipeline to form a circulation pipeline; and the second cathode reaction area is connected with the main cathode electrolyte tank through a pipeline to form a circulating pipeline. 
     By adopting the technical scheme, the main reference battery can monitor the soc state of the main electrical energy storage center in real time, and adjust the soc state in time, so that the service life of the all-vanadium redox flow battery is prolonged. 
     Optionally, the sub electric energy storage center includes sub positive electrode electrolyte tank and sub negative electrode electrolyte tank, sub positive electrode electrolyte tank passes through the pipe connection with main positive electrode electrolyte tank, sub negative electrode electrolyte tank with main negative electrode electrolyte tank passes through the pipe connection, sub positive electrode electrolyte tank with the battery stack passes through the pipe connection, constitutes sub positive electrode circulation pipeline, sub negative electrode electrolyte tank with the battery stack passes through the pipe connection, constitutes sub negative electrode circulation pipeline. 
     By adopting the technical scheme, when the main electrical energy storage center cannot meet the charging and discharging requirements of the power distribution subsystem, the sub-electric energy storage center supplements the current power distribution point so as to meet the charging and discharging requirements of the power distribution point on the all-vanadium redox flow battery. 
     Optionally, a sub-reference cell is connected in parallel between the sub-anode circulation pipeline and the sub-cathode circulation pipeline, the sub-reference cell comprises a third anode reaction area and a third cathode reaction area, the third anode reaction area and the sub-anode electrolyte tank are connected through a pipeline to form a circulation pipeline, and the third cathode reaction area and the sub-cathode electrolyte tank are connected through a pipeline to form a circulation pipeline. 
     Through adopting above-mentioned technical scheme, parallelly connected sub-reference cell between sub-positive pole circulation pipeline and sub-negative pole circulation pipeline, sub-reference cell detects sub-electric energy storage center&#39;s soc state, cooperates through control module and control subsystem, balances electrolyte, can make sub-electric energy storage center&#39;s soc state tend towards stability, and then improves all vanadium redox flow battery&#39;s life. 
     Optionally, the power distribution subsystem further comprises a BMS subsystem, the battery stack comprising a plurality of monolithic electric reactors; the input end of the BMS subsystem is electrically connected with the positive electrode and the negative electrode of the sub-reference battery, the output end of the battery stack and the input end of the PCS subsystem are electrically connected with the BMS subsystem, and the output end of the BMS subsystem is electrically connected with the control module. 
     By adopting the technical scheme, the input end of the BMS subsystem, the input end of the PCS subsystem and the positive and negative electrodes of the sub-reference battery are electrically connected, the voltage generated by each single-chip electric reactor of the battery stack and the soc state of the sub-electric energy storage center can be detected, the detection result is transmitted to the control module, a worker can monitor the internal reaction condition and the soc state of the battery stack and adjust the all-vanadium redox flow battery according to the monitoring result, so that the all-vanadium redox flow battery is in the optimal state. 
     Optionally, the control module is a programmable logic controller. 
     By adopting the technical scheme, the programmable logic controller performs simple logic calculation on the acquired data and sends the calculation result to the control subsystem, so that the control subsystem can detect the operation condition of each power distribution subsystem, and the possibility of accidents is reduced. 
     The present application is described in further detail below with reference to  FIGS.  1 - 2   . 
     The embodiment of the application discloses a distributed large-scale system of an all-vanadium redox flow battery. Referring to  FIG.  1   , the distributed large-scale system of the all-vanadium redox flow battery comprises a main power storage center  1 , a plurality of power distribution subsystems  2  and a control subsystem  3 , wherein the main power storage center  1  is respectively connected with the plurality of power distribution subsystems  2  through pipelines; the main electrical energy storage center  1  and the power distribution subsystem  2  are both electrically connected to the control subsystem  3 , which may be a communication bus connection. 
     When the output power inside the power distribution subsystem  2  does not meet the preset power, the control subsystem  3  receives a power output shortage signal transmitted by the power distribution subsystem  2 , and dispatches the electrolyte of the main electrical energy storage center  1  to enter the power distribution subsystem  2 , so that the electrolyte in the power distribution subsystem  2  is increased, and the condition that the power supply of the power distribution subsystem  2  is insufficient is met. 
     In the process of charging the all-vanadium redox flow battery, when the electrolyte capacity in the power distribution subsystem  2  is not enough to meet the energy storage function, the electrolyte in the main electrical energy storage center  1  needs to be dispatched into the power distribution subsystem  2 , the electrolyte capacity in the power distribution subsystem  2  is increased, and the storage of electric energy is supported. 
     In this embodiment, the main electrical energy storage center  1  may be provided near the power distribution subsystem  2  requiring the largest power to satisfy the power requirement of the power distribution subsystem  2 . 
     The main electrical energy storage center  1  comprises a main anode electrolyte tank  11  and a main cathode electrolyte tank  12 , and the capacity of the main anode electrolyte tank  11  and the capacity of the main cathode electrolyte tank  12  can be enlarged. The main anode electrolyte tank  11  is connected with the power distribution subsystems  2  through a main anode circulation pipeline  111 , the main cathode electrolyte tank  12  is connected with the power distribution subsystems  2  through a main cathode circulation pipeline  121 , main circulation pumps  13  are arranged on pipelines, close to the main electrical energy storage center  1 , on the main anode circulation pipeline  111  and the main cathode circulation pipeline  121 , and the main circulation pumps  13  convey electrolyte of the main electrical energy storage center  1  into the power distribution subsystems  2 . 
     In addition, devices such as a temperature sensor and a liquid level sensor can be arranged in the main anode electrolyte tank  11  and the main cathode electrolyte tank  12 , and both the temperature sensor and the liquid level sensor are connected with the control subsystem  3  through a network. 
     The temperature sensor and the liquid level sensor transmit detected data to the control subsystem  3  in real time, the control subsystem  3  compares the received data with a preset range, and when the detected temperature is lower than a preset temperature minimum value, the control subsystem  3  controls the main circulating pump  13  to increase the rotating pump speed so as to increase the reaction rate; when the detected temperature is higher than the maximum value of the preset temperature, the control subsystem  3  controls the main circulating pump  13  to reduce the pump speed and reduce the reaction rate. When the detected liquid level is lower than the preset lowest liquid level and/or higher than the preset highest liquid level, an alarm signal is sent out to remind a worker to process in time. 
     Referring to  FIGS.  1  and  2   , the power distribution subsystem  2  includes a battery stack  21 , a control module  22 , a BMS subsystem  23 , and a PCS subsystem  24 . A first anode reaction zone  211  and a first cathode reaction zone  212  are arranged in the cell stack  21 , the first anode reaction zone  211  and the main anode electrolyte tank  11  are connected through a pipeline to form a main anode circulation pipeline  111 , and the first cathode reaction zone  212  and the main cathode electrolyte tank  12  are connected through a pipeline to form a main cathode circulation pipeline  121 . 
     Electromagnetic valves and manual valves are arranged on the main anode circulating pipeline  111  and the main cathode circulating pipeline  121 , signal lines of the electromagnetic valves are electrically connected with the control module  22 , and when the control module  22  controls the electromagnetic valves to be opened, the electrolyte flows into the power distribution subsystem  2  from the main electrical energy storage center  1  through the driving of the main circulating pump  13 . Acquisition modules  25  are arranged in the first cathode reaction area  212  and the first anode reaction area  211 , each acquisition module  25  comprises a pressure sensor and a temperature sensor, the pressure sensors and the temperature sensors are electrically connected with the control module  22 , the control module  22  is connected with a display terminal  26 , and the display terminal  26  can be a terminal such as a smart phone, a desktop computer, a tablet computer and a notebook computer. 
     The pressure sensor and the temperature sensor transmit the detected data to the control module  22 , and the control module  22  compares the received data with preset data and transmits the comparison result to the control subsystem  3 . When the temperature value acquired by the temperature sensor is lower than the preset temperature value, the control subsystem  3  controls the speed of the main circulating pump  13  to be increased, so that the reaction speed of the electrolyte is increased; when the temperature value acquired by the temperature sensor is higher than the preset temperature value, the control subsystem  3  controls the speed of the main circulating pump  13  to be reduced, and the reaction rate of the electrolyte is reduced; when the pressure value collected by the pressure sensor is higher than the preset pressure value, the control subsystem  3  controls the speed of the main circulating pump  13  to be reduced, so that the pressure applied to the battery stack  21  is reduced, and the possibility of damage to the battery stack  21  is reduced. 
     Further, in order to reduce the influence of the temperature of the electrolyte on the reaction rate, heat exchangers for adjusting the temperature of the electrolyte are disposed at a position where the main anode circulation pipe  111  is close to the cell stack  21  and at a position where the main cathode circulation pipe  121  is close to the cell stack  21 . When the temperature of the electrolyte is too high, cold water can be added into the heat exchanger to reduce the temperature of the electrolyte, so that the reaction rate is controlled; when the temperature of the electrolyte is too low, hot water can be added into the heat exchanger to increase the temperature of the electrolyte, so that the reaction rate is controlled. 
     The anode and the cathode of the battery stack  21  are electrically connected with the input end of the PCS subsystem  24 , and the PCS subsystem  24  can convert direct current generated by the reaction of electrolyte in the battery stack  21  into alternating current required by the power distribution subsystem  2 ; the output of the PCS subsystem  24  is electrically connected to an electrical energy load point for coupling ac power to an external load. 
     The power supply system  4  is arranged outside the distributed large-scale system of the all-vanadium redox flow battery, the PCS subsystem  24  is electrically connected with the electric energy access point, the PCS subsystem  24  is electrically connected with the electric energy load point, when the output power of the power supply system  4  is larger than the power requirement of the power distribution subsystem  2 , the power supply system  4  is electrically connected with the electric energy access point, and the electric energy of the power supply system  4  is converted into direct current power through the conversion of the PCS subsystem  24  so as to store energy. 
     When the all-vanadium redox flow battery discharges, controlling the electric energy load point to be conducted with an external load, and outputting the external load; when the all-vanadium redox flow battery is charged, the electric energy access point is controlled to be communicated with the power supply system  4 , then alternating current is converted into direct current through the PCS subsystem  24 , then the direct current is input into the battery stack  21  to ionize electrolyte, and further electric energy is converted into chemical energy and stored in the main electrical energy storage center  1 . 
     When a plurality of single-chip electric reactors are arranged in the battery stack  21 , the input end of the PCS subsystem  24  is electrically connected with the input end of the BMS subsystem  23 , the output end of the BMS subsystem  23  is electrically connected with the control module  22 , the BMS subsystem  23  can detect the direct current output voltage of each single-chip electric reactor and transmit the detected data to the control module  22 , the control module  22  transmits the received data to the control subsystem  3 , and the control subsystem  3  monitors the running state of the battery stack  21  according to the detected data, so that the possibility of hidden danger in the battery stack  21  is reduced. 
     In this embodiment, the sub-electrical energy storage center  5  is provided for power distribution subsystems  2  where the electrolyte flow rate is significantly reduced and/or where the preset power requirements are not met. The sub-electrical energy storage center  5  comprises a sub-anode electrolyte tank  51  and a sub-cathode electrolyte tank  52 , the capacity of both the sub-anode electrolyte tank  51  and the capacity of both the sub-cathode electrolyte tank  52  can be increased, and the sub-anode electrolyte tank  51  is connected with the first anode reaction area  211  through a pipeline to form a sub-anode circulation pipeline  511 ; the sub-anode electrolyte tank  52  is connected with the first cathode reaction zone  212  through a pipeline to form a sub-anode circulation pipeline  521 . The sub-circulation pumps  53  are respectively arranged on the pipelines close to the sub-electrical energy storage center  5  on the sub-anode circulation pipeline  511  and the sub-cathode circulation pipeline  521 , and the sub-circulation pumps  53  convey the electrolyte in the sub-electrical energy storage center  5  to the battery stack  21  of the power distribution subsystem  2 , so that the reaction rate of the electrolyte in the battery stack  21  is accelerated, and the power requirement of the power distribution subsystem  2  is further met. 
     The sub-electrical energy storage center  5  is also connected with the main electrical energy storage center  1  by a pipeline, wherein the sub anode electrolyte tank  51  is connected with the main anode electrolyte tank  11  by a pipeline, and the sub cathode electrolyte tank  52  is connected with the main cathode electrolyte tank  12  by a pipeline. When the control subsystem  3  monitors that the concentration of the electrolyte in the sub-electrical energy storage center  5  is too low or too high, the electrolyte in the main electrical energy storage center  1  needs to be conveyed to the sub-electrical energy storage center  5  through the main circulating pump  13  to balance the electrolyte in the sub-electric energy storage center  5 , so that the power requirement of the power distribution subsystem  2  is met. 
     Further, since the soc state in the electrolyte tank changes after the all vanadium redox flow battery operates for a period of time, the soc state needs to be monitored in real time. In order to monitor the soc state of the main electrical energy storage center  1  and the sub electrical energy storage center  5 , it is necessary to connect the main reference cell  14  in parallel between the main electrical energy storage center  1  and the power distribution subsystem  2 , and the sub reference cell  54  in parallel between the sub-electrical energy storage center  5  and the cell stack  21 . 
     The main reference cell  14  includes a second anode reaction zone  141  and a second cathode reaction zone  142 , the second anode reaction zone  141  is piped to the main positive electrolyte tank  11 , the second cathode reaction zone  142  is piped to the main negative electrolyte tank  12 , and the positive and negative electrodes of the main reference cell  14  are electrically connected to the BMS subsystem  23 . 
     When the electrolyte is supplied to the power distribution subsystem  2  by the main electrical energy storage center  1 , a part of the positive electrolyte and the negative electrolyte enters the main reference cell  14  to react and discharge electric energy, and then the soc state value of the main electrical energy storage center  1  is calculated by the BMS subsystem  23 , and the soc state value of the main electrical energy storage center  1  is transmitted to the control subsystem  3  by the BMS subsystem  23 . When the soc state value is lower, the control subsystem  3  controls the power distribution subsystems  2  to supplement the electrolyte of the main electrical energy storage center  1 ; when the overall soc state value of the all-vanadium redox flow battery system is too low, an alarm signal is sent out in time to remind a worker to enlarge the electrolyte capacity and adjust the soc state value. 
     The sub-reference cell  54  comprises a third anode reaction area  541  and a third cathode reaction area  542 , the third anode reaction area  541  is connected with a sub-anode electrolyte tank  51  through a pipeline, the third cathode reaction area  542  is connected with a sub-cathode electrolyte tank  52  through a pipeline, the anode and the cathode of the sub-reference cell  54  are electrically connected with the input end of the BMS subsystem  23 , the BMS subsystem  23  can collect and calculate the voltage released by the sub-reference cell  54  and transmit the monitoring data to the control module  22 , and the control module  22  adjusts the rotating speed of the sub-circulation pump  53  according to the received data, so that the reaction rate of the cell stack  21  is controlled, and the power output of the all-vanadium redox flow cell is ensured. 
     The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application. 
     It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the following claims.