Investigations on Performance Analysis of Independent Real and Reactive Power Control of VSC - HVDC Transmission Systems

Abstract

HVDC systems are attractive alternatives to increase transmittable power over long distances. The power loss of a DC line is lower than that of a corresponding AC line of the same power rating. The HVDC transmission based on Voltage Source Converters (VSC) uses IGBT's (Insulated Gate Bipolar Transistors) and PWM technique maintain the desired level voltage. This paper proposes the modern adaptive backstepping controller for Voltage Sourced Converter (VSC) based HVDC. The adaptive backstepping controller adapts non linear nature of the VSC based HVDC systems which uses parameter uncertainties. The Lyapunov functions are adapted to deduce the control laws by step by step procedure. Based on the adaptive backstepping method, the final control law can be deduced step by step. The performance of the proposed controller has been investigated under different operating conditions like step changes in active and reactive power, including post fault recovery. The efficacy of the implemented backstepping controller is presented with VSC based HVDC Transmission systems with digital simulation tool of PSCAD/EMTDC. The results of simulation under broad choice of operating region show that the proposed controller effectively contribute towards the bidirectional as well as independent flow of real and reactive power flow control of VSC-HVDC system.