Performance analysis of a voltage source converter HVDC system connected to an independent power generating station

Abstract

This paper presents the mathematical model and analysis of a complete VSC-HVDC system. At sending end, AC power is supplied from a generating station to VSC- HVDC and to an AC line connected to Central grid. Constant power controller for the VSC HVDC system is designed to transfer a definite amount of power on DC link. To ensure constant DC voltage in the DC link, DC voltage controller is used in the inverter side of the DC link. In both converters, reactive power controllers are used to ensure the exchange of reactive power between the converter and the AC system. The reactive power requirement at the inverter side of the VSC-HVDC link is derived from the AC voltage controller. Independent control of active and reactive power is implemented in the model. In the literature, very few papers are available which discuss the performance of VSC HVDC implementing all the four controllers. However, in this paper, a detailed mathematical analysis for the system under consideration is discussed. Two level converter structure is employed to analyze the performance of different controllers designed. The simulation results show that, dynamic control of the rectifier and inverter is achieved with fast response. It is also shown that, the power flow control in AC line is improved due to the power controllability in the DC link.