METHOD AND SYSTEM FOR MONITORING STATE OF CHARGE (SOC) OF FLOW BATTERY SYSTEM, FLOW BATTERY BASED ON REDUNDANCY DESIGN OF SOC DETECTION DEVICE, METHOD AND DEVICE FOR DETERMINING ACTUAL CAPACITY OF FLOW BATTERY, AND METHOD AND SYSTEM FOR ESTIMATING INPUT-OUTPUT CHARACTERISTIC OF FLOW BATTERY ALTERNATING CURRENT SIDE

A method and system for monitoring a state of charge (SOC) of a flow battery system, flow battery based on a redundancy design of an SOC detection device, method and device for determining an actual capacity of the flow battery, and method and system for estimating an input-output characteristic of a flow battery alternating current side, the monitoring method comprising the following steps: determining SOCs of at least two pairs of different monitoring positions, any pair of monitoring positions being as followings: an inside of an anode electrolyte storage tank(2) and an inside of a cathode electrolyte storage tank(3), inside an anode electrolyte outlet pipeline(6) of a stack and inside a cathode electrolyte outlet pipeline(7) of the stack, or inside an anode electrolyte inlet pipeline(8) of the stack and inside a cathode electrolyte inlet pipeline(9) of the stack; and according to the SOCs respectively corresponding to each pair of monitoring positions, acquiring an SOCsumof a flow battery system. The method ensures acquiring an SOC monitoring result timely and accurately, thus facilitating an increase in a usage efficiency of a flow battery, extending the service life of the battery, and accurately managing a flow battery system.