Dynamic equivalent modeling of wind farm with DDPMSG wind turbine generators

In order to reduce the complexity of simulation system with wind farm (WF) model and computation time while ensuring the precision, taking the consistency of WF output characteristics at point of common connection (PCC) as objective, a dynamic equivalent modeling method which is appropriate for WF with direct-driven permanent magnet synchronous generators (DDPMSGs) wind turbine generator (WTG) is proposed in this paper. Wind speed, turbine angular speed and pitch angle, which can represent operating point of DDPMSG WTG, are adopted as clustering indexes. WTGs are divided into groups by system clustering algorithm. The WTGs in the same group have high similarity of operating characteristic, while WTGs in different groups are different. The parameters of equivalent WTGs and equivalent collector systems are calculated based on the power output characteristics constant principle and voltage loss constant principle. Taking an actual grid-connected WF comprising 66 DDPMSG WTGs in China as an example, output characteristics of detailed model and equivalent model of WF are compared. The simulation results show that before and after the equivalence the WF output characteristics at PCC is consistent in the disturbance of both system and turbine sides, thus the proposed equivalent method is reasonable and effective.