An equivalent model for simulating VSC based HVDC

In this paper, the equivalent simulation model of a VSC (voltage source converter) based HVDC system is developed by ignoring the switching ripples. In this model, the VSC's reaction to the AC side is represented by an equivalent voltage controlled voltage source, and the VSC's reaction to the DC side is represented by an equivalent current controlled current source. Because the internal switching action and the topological structure of the VSC no longer need to be considered, the simulation speed is raised greatly, further more, the study of device level as well as system level control strategy become very convenient. It is shown by simulation results that with the proposed equivalent simulation model, the simulation speed is raised more then twenty times, and the dynamic characteristics of the VSC based HVDC system can be effectively expressed, besides, the asymmetrical operation condition can also be studied by this model.