A Dynamic Equivalent Method Based on Composite Load for Hydropower Generator Groups with Motor Load

With the rapid development of distributed hydropower technology, the issue of the equivalence of small and medium hydropower systems is urged to be solved. According to the China power grid data, the small and medium hydropower areas often contain motor (especially in the southwest of China). This paper presents a dynamic equivalent method combined 3rd generator and a parallel composite load (including a static characteristic ZIP load and a motor load) model, the parameters of which can be identified by the self-adaptive control parameters modified differential evolution (SACPMDE) algorithm. The proposed method is verified in simulation with the grid data from Sichuan and Hunan provinces in China which have abundant hydropower systems. The simulation results reflect that the dynamic responses of the proposed equivalent model are more consistent with that of the detailed model, even when the equivalent area has a certain amount of motor. Moreover, the parameters identified by SACPMDE is stable. Therefore, the presented method has high precision and it is suitable to solve the problem of equivalence of small and medium hydropower systems with a certain amount of motor.