Mixed integral electromagnetic transient simulation decoupling model for two-level voltage source converter

Due to the time-varying admittance matrix of the detailed electromagnetic transient model of VSC, it is inefficient to simulate large power grids with large-scale new energy stations. To solve this problem, this paper studies the mixed integration method, and proposes a decoupling model based on this method, which has simple decoupling circuit, constant admittance matrix, and can account for the internal characteristics of the converter. Firstly, based on the state equation of VSC converter, the Mixed integral model of two-level VSC converter is constructed by using matrix splitting and delay techniques to realize the decoupling of AC and DC. Then, the calculation of parameters of the decoupling model is simplified by taking advantage of the mutual exclusion of the longitudinal commutation of the upper and lower VSC bridge arms, so that the admittance matrix of the system is constant and the calculation speed is further improved. The numerical results show that the proposed method can improve the calculation speed while maintaining high precision.