A mathematical framework for modelling of current source converter based high voltage DC transmission systems

Abstract

Transmission of electrical power through High Voltage Direct Current (HVDC) has attracted the attention of several researchers in the recent years. To investigate the performance of HVDC transmission systems, a complete linear mathematical model is required. In this paper, a well-developed linear continuous model of current source converter based twelve pulse HVDC transmission systems is presented. In which, the converter AC system is represented by damped LLR equivalents at fundamental frequency and at the third harmonic. Also, they are equipped with double tuned harmonic filter and second order high pass filter to suppress the AC harmonics and a capacitor for reactive power compensation. The DC system is secured with rectifier current control, inverter current control, inverter voltage control and inverter extinction angle control. The HVDC transmission system model is implemented in the MATLAB/Simulink environment and the performance of the system has been investigated by observing the rectifier side AC quantities, rectifier DC quantities, inverter side AC quantities and inverter DC quantities.