Coherency-based dynamic equivalence method for power system centralized large scale wind power

Applied in power system integrated with large scale wind farms, an equivalence method based on parameter aggregation is presented in this paper. The method is used to get parameter aggregation of equivalent model of coherent wind farms, considering the reserve of dynamic electric load at the boundary nodes. Transient stability simulation of the original system and equivalent network is conducted and compared by using 4 different capacity criteria, which are based on weighted average efficiency, average efficiency, maximum efficiency and minimum efficient. The tests show that, the simulation result of equivalent network is closest to the original network when the capacity of equivalent wind farm is selected by the minimum wind farm efficiency. For validation purposes, this equivalent method is applied to an actual network of 99 buses. Results show that the reduced system retains the dynamic performance of the original system with good accuracy. In addition, the presented approach is also tested on a typical interconnected system of CIGRE B4-39 wind farm system standard network and the results show that the proposed method provides better approximation if the proportion of wind power is larger than 4% of power system capacity.