Table 3 The main procedures of the parameter identification method

Step 1: Present the range of nonlinear parameters and stopping criteria.

Step 2: Randomly generate the population in the range.

Step 3: Generate the U_c and/or U_w vectors using discretised model equations in Table 2.

Step 4: Identify [U_oc, R_i] using least squares and output the RMSE.

Step 5: Evaluate the stopping criteria. If the criteria are met, stop and return the best solution. If not, go to the next step.

Step 6: Generate a new population by crossover, mutation and selection. Go to Step 3.