A dynamic on-line parameter identification and full-scale system experimental verification for large synchronous machines

An on-line parameter identification and full-scale experimental verification for large synchronous machines (>50 MVA) is presented in this paper. A step change of excitation is imposed to a generator when the machine is in normal operation. The transient voltages, currents and the power angle are recorded. Based on the large disturbance equations and using the measured power angle as an observation argument in an identification algorithm, the synchronous machine electrical parameters (x_d, x_d\´, x_d", T_do\´, T_do", x_q, x_q", T_qo") and mechanical parameters (H,D) are obtained. In addition, the system parameters (equivalent infinite bus voltage V_bus and line reactance x_e) are identified as well. The proposed method has been repetitively applied to turbogenerators and hydrogenerators with capacities up to 300 MVA. In particular, a field test has been conducted on a system with a capacity of 15000 MVA. The experimental results from all of the full-scale tests are consistent and the effectiveness of the proposed on-line identification method is verified. The plant experiences indicate that by adopting the identified parameters, the stability margin of the generator can be improved by up to 5%, resulting in 30-50 MVA more power generation