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 alternating-current side of flow battery

1. A method for monitoring state of charge (SOC) of a flow battery system, the flow battery system comprising a stack, an anode electrolyte storage tank, a cathode electrolyte storage tank and an electrolyte circulating pipeline, wherein the monitoring method comprises the following steps:

Step 1: determining SOCs of at least two pairs of different monitoring positions, any pair of monitoring positions being as followings: an inside of the anode electrolyte storage tank and an inside of the cathode electrolyte storage tank, inside an anode electrolyte outlet pipeline of the stack and inside a cathode electrolyte outlet pipeline of the stack, or inside an anode electrolyte inlet pipeline of the stack and inside a cathode electrolyte inlet pipeline of the stack;

Step 2: configuring coefficients according to a ratio of a power to a capacity of the flow battery system; according to the SOCs respectively corresponding to each pair of monitoring positions, acquiring a SOC sum of a flow battery system;

calculating the SOC sum of the flow battery system according to a formula SOC sum =ΣN×SOC n , wherein N is coefficients, N is the sum of n coefficients and equal to 1, n is pairs of monitoring positions, n is equal to 2 or 3.

2. The method for monitoring state of charge (SOC) of a flow battery system according to claim 1 , wherein when three pairs of monitoring positions are present, the Step 2 is specifically as follows:

calculating the SOC sum of the flow battery system according to a formula SOC sum =A×SOC a +B×SOC b +C×SOC c ; wherein A, B and Care coefficients, and A+B+C=1; SOC a is SOC corresponding to monitoring positions: the inside of the anode electrolyte storage tank and the inside of the cathode electrolyte storage tank; SOC b is SOC corresponding to monitoring positions: inside the anode electrolyte outlet pipeline of the stack and inside the cathode electrolyte outlet pipeline of the stack; SOC c is SOC corresponding to monitoring positions: inside the anode electrolyte inlet pipeline of the stack and inside the cathode electrolyte inlet pipeline of the stack.

3. The method for monitoring state of charge (SOC) of a flow battery system according to claim 1 , wherein when two monitoring positions are present, the Step 2 is specifically as follows:

calculating the SOC sum of the flow battery system according to formulas SOC sum =A×SOC a +B×SOC b , SOC sum =A×SOC a +C×SOC c or SOC sum =B×SOC b +C×SOC c ;

wherein A, B and C are coefficients, and the sum of all coefficients in each formula is equal to 1; SOC a is SOC corresponding to monitoring positions: the inside of the anode electrolyte storage tank and the inside of the cathode electrolyte storage tank; SOC b is SOC corresponding to monitoring positions: inside the anode electrolyte outlet pipeline of the stack and inside the cathode electrolyte outlet pipeline of the stack; SOC c is SOC corresponding to monitoring positions: inside the anode electrolyte inlet pipeline of the stack and inside the cathode electrolyte inlet pipeline of the stack.

4. The method for monitoring state of charge (SOC) of a flow battery system according to claim 2 , wherein when three pairs of monitoring positions are present, the step of configuring coefficients A, B and C according to the ratio of the power to the capacity of the flow battery system is specifically as follows:

(1) determining whether the ratio of the power to the capacity of the flow battery system is larger than or equal to a first preset value, if so, executing Step (2), and if not, executing Step (3);

(2) configuring 0.1≤A≤0.3, 0.5≤B≤0.8, 0.1≤C≤0.3, and executing Step 2;

(3) determining whether the ratio of the power to the capacity of the flow battery system is smaller than or equal to a second preset value, if so, executing Step (4), and if not, executing Step (5);

(4) configuring 0.1≤A≤0.3, 0.1≤B≤0.3, 0.5≤C≤0.8, and executing Step 2;

(5) calculating a SOC average value SOC average of each pair of monitoring positions via SOC average =(SOC a +SOC b +SOC c )/3, and executing Step (6);

(6) when 0<SOC average 20%, configuring 0.1≤A≤0.33, 0.33≤B≤0.6 and 0.1≤C≤0.33, and executing Step 2;

when 20%<SOC average ≤80%, configuring A=B=C, and executing Step 2;

when 80%<SOC average <100%, configuring 0.1≤A≤0.33, 0.1≤B≤0.33 and 0.33≤C≤0.6, and executing Step 2.

5. The method for monitoring state of charge (SOC) of a flow battery system according to claim 3 , wherein when two pairs of monitoring positions are present, the step of configuring coefficients A, B and C according to the ratio of the power to the capacity of the flow battery system is specifically as follows:

i. determining whether the ratio of the power to the capacity of the flow battery system is larger than or equal to a first preset value, if so, executing Step ii, and if not, executing Step iii;

ii. with respect to a formula SOC sum =A×SOC a +B×SOC b , configuring 0.1≤A≤0.3 and 0.7≤B≤0.9, and executing Step 2;

with respect to a formula SOC sum =A×SOC a +C×SOC c , configuring 0.4≤A≤0.5 and 0.5≤C≤0.6, and executing Step 2;

with respect to a formula SOC sum =B×SOC b +C×SOC c , configuring 0.7≤B≤0.9 and 0.1≤C≤0.3, and executing Step 2;

iii. determining whether the ratio of the power to the capacity of the flow battery system is smaller than or equal to a second preset value, if so, executing Step iv, and if not, executing Step v;

iv. with respect to a formula SOC sum =A×SOC a +B×SOC b , configuring 0.4≤A≤0.5 and 0.5≤B≤0.6, and executing Step 2;

with respect to a formula SOC sum =A×SOC a +C×SOC t , configuring 0.1≤A≤0.3 and 0.7≤C≤0.9, and executing Step 2;

with respect to a formula SOC sum =B×SOC b +C×SOC c , configuring 0.1≤B≤0.3 and 0.7≤C≤0.9, and executing Step 2;

v. calculating a SOC mean SOC mean of any two pairs of monitoring positions via SOC mean =(SOC a +SOC b )/2, SOC mean =(SOC a +SOC c )/2 or SOC mean =(SOC b +SOC c )/2, and executing Step vi;

vi. when 0<SOC mean ≤20%:

with respect to a formula SOC sum =A×SOC a +B×SOC c , configuring 0.2≤A≤0.5 and 0.5≤B≤≤0.8, and executing Step 2;

with respect to a formula SOC sum =A×SOC a +C×SOC c , configuring 0.4≤A≤0.5 and 0.5≤C≤0.6, and executing Step 2;

with respect to a formula SOC sum =B×SOC b +C×SOC x , configuring 0.5≤B≤0.8 and 0.2≤C≤0.5, and executing Step 2;

when 20%<SOC mean ≤80%, configuring A=B=C;

when 80%<SOC mean <100%:

with respect to a formula SOC sum =A×SOC a +B×SOC b , configuring 0.4≤A≤0.5 and 0.5≤B≤0.6, and executing Step 2;

with respect to a formula SOC sum =A×SOC a +C×SOC c , configuring 0.2≤A≤0.5 and 0.5≤C≤0.8, and executing Step 2;

with respect to a formula SOC sum =B×SOC b +C×SOC c , configuring 0.2≤B≤0.5 and 0.5≤C≤0.8, and executing Step 2.