State Estimation for Hybrid AC/DC Power Grids Based on Pseudo Measurement Modelling of Converters

Hybrid AC/DC power grids with various distributed power generations are considered to be the emerging architecture of future power system, where highly penetrated power electronic devices (Voltage Source Converters) as well as DGs can increase operation flexibilities, and would also cause new difficulties for system state estimation. Therefore, it is necessary to develop pseudo measurement modelling method for converters and DGs, especially when the control parameters of converters are unknown. In this paper, the model of VSCs considering their losses are used for pseudo measurement modelling of converters: control information-based modelling method for the observable VSCs and Gaussian Mixture Model (GMM)-based modelling method for unobservable VSCs. Developed from Weighted Least Squares (WLS), an improved AC/DC hybrid grid state estimation algorithm is proposed. Simulations for algorithm validations are carried out with modified IEEE-14 bus system. Results show that the effectiveness of proposed state estimation algorithm does not depend on measurement configurations or communications between operation center and VSC stations, and shows robustness with data errors existing in the adopted historic DG power outputs.