Electrical Control And Energy Efficiency Analysis Of Vanadium Redox Battery

The vanadium redox battery(VRB)has the characteristics of long life,safety,reliability,flexible system design and low cost in the whole life cycle.It is very suitable for building large capacity and long time constant energy storage system.One of the key problems to be solved is how to satisfy the requirements of different dispatching instructions and maximize the value of VRB energy storage system on the premise of ensuring security,controllability and efficiency.Therefore,this paper studies the energy efficiency improvement and electronic control of VRB energy storage system,and establishes a monitoring and management platform.The main contents are as follows:(1)Based on the current status of VRB modeling at home and abroad,according to the basic structure of VRB and the principle of electrochemical reaction,the equivalent circuit model of VRB is constructed,and the influence of electrolyte flow on the performance of VRB is analyzed.The VRB equivalent circuit model consists of three sub-modules: overpotential module,ion diffusion module and fluid loss module.(2)Analyse the formation mechanism of shunt current in VRB reactor,set up equivalent model of shunt current,calculate and analyze the distribution of shunt current inside the reactor.The shunt current sizes of four transfusion pipelines with different sizes and lengths are measured in the field.Analyze the factors affecting shunt current size and reduce measures through field test and experimental simulation.(3)From the two aspects of flow management strategy and design of VRB energy storage system,the ways to improve the efficiency of VRB energy storage system are analyzed comprehensively.In the process of VRB operation,the VRB energy efficiency optimization operation method with hourly flow control is used to dynamically select the optimal electrolyte flow rate according to the change of battery output power,so as to improve the system efficiency of VRB.In the design of VRB system,the stack structure and connection mode are optimized to suppress shunt current.Rationally designing the structure of the transfusion pipeline and balancing the distribution of electrolyte in the pipeline can reduce the additional energy loss due to fluid pressure and shunt current.(4)The MW-level VRB energy storage system is studied,and the basic structure of MW-level energy storage system is analyzed.The black-start scheme of VRB energy storage system is designed to achieve long standby and black-start of VRB energy storage system.Battery Manage System(BMS)is designed to detect the voltage and current of VRB stack and monitor the safe operation of the stack.The monitoring and management platform of MW-level VRB energy storage system is established,and the monitoring and energy management of MW-level VRB energy storage system operation parameters are implemented.