STEADY-STATE MODEL AND ITS NONLINEAR CONTROL OF VSC-HVDC SYSTEM

Abstract

In this paper,the mathematical model and its control strategy of the VSC HVDC system are studied.Because the voltage source converter has two degrees of freedom for control,four controlled variables in the two volage source converters of the HVDC system are determined.The steady state mathematical model for the VSC HVDC system is developed in the paper,and the approximately decoupled relationship between the two controlling variables and the two controlled variables in the voltage source converter is proposed.An inverse steady state model controller for the VSC HVDC system is proposed.The control strategy for the VSC HVDC systemis using the inverse steady state model controller to trace the operating point and using the two decoupled controlling loops to eliminate the steady state deviations.Simulation results show the validity of the established steady state model and the effectiveness of the proposed control strategy.