SLIDING MODE CONTROL WITH TIME DELAY DISTURBANCE ESTIMATOR FOR POWER FLOW CONTROL USING VSC-HVDC

摘要

This paper presents a Sliding Mode Control with Time Delay Control Disturbance Estimator (SMCTDDE) as an effective control method for systems with uncertain dynamics and unpredictable disturbances. The SMCTDDE method is applied in the case of power flow reference tracking of a Voltage Source Converter High Voltage Direct Current (VSC-HVDC) transmission system. Based on Kirchhoff's equations and synchronous (d-q) transformation, a state space dynamic model of VSC-HVDC interconnecting two asynchronous electrical grids is developed. The control algorithm uses a Time Delay Estimator (TDE) method with recent past data to estimate terms referring to uncertain dynamics and disturbances in the system. Through the stability analysis, stable design gains are found to insure robustness and better performance while keeping the delay time at an appropriate level. For the VSC-HVDC system during the delay time, the TDE method with the switching term is shown to provide a very satisfactory performance.