Wide-area Measurement-based Design Of Nonlinear Modulation Strategy For HVDC Systems

As a result of the implementation of the projects of"power transmission from West China to East China"and"Nation-wide interconnection", the China Southern Grid has already become a hybrid power system, which contains not only multi-infeed HVAC links but also multi-infeed HVDC links. Compared with single-infeed HVDC link, multi-infeed HVDC links have larger transmission capacity and more flexible operation modes. For the time being, there is very little research on multi-infeed HVDC links, and no systematic results have been achieved.Up to now, many decentralized controllers using local signals are installed in modern power system to guarantee its stability. However, decentralized control has been challenged by many researchers because local control signal lacks adequate observability of the overall system dynamics. In recent years, much research is, therefore, focused on wide-area measurement-based centralized controller, which employs a combination of global signals (remote stabilizing signals).With the ability to rapidly regulate active power flow, DC modulation control is a well-accepted technique to enhance ac system's performance or to damp oscillations. The study object of this dissertation is hybrid power system, which contains not only multi-infeed HVAC links but also multi-infeed HVDC links. The objective is to design advanced nonlinear DC current modulation strategies for HVDC links, the implementation of which is based on wide area measurement system, to improve the stability of the receiveing-end AC power system and to damp the power oscillation on AC transmission lines.The sending-end AC network of each AC link is equivalented as a generator, which merges into the receiving-end AC network. The expanded receiving-end AC network is detailedly modeled as a multi-machine power...