真双极多端柔性直流输电系统多目标协同控制策略

目前，基于电压源型换流器的多端柔性直流输电（VSC-MTDC）技术已得到广泛应用。真双极VSC-MTDC换流站中正、负极换流器具有可独立控制的特点，为进一步提升真双极VSC-MTDC系统的控制灵活性，首先对同一换流站中正负极独立换流器分别采用不同控制策略的可行性及存在的交互影响进行了理论分析，进一步提出了真双极VSC-MTDC的多目标协同控制策略。同一换流站的正、负极独立换流器分别采取不同的控制策略，并针对系统不同运行工况，通过相应的极间协同控制策略，同时实现了对交流电压控制稳定性和双极直流电网有功功率消纳能力的提升。基于PSCAD/EMTDC搭建真双极VSC-MTDC仿真系统，验证了各种运行工况下所提控制策略的适用性和有效性。

Multi-objective Coordinated Control Strategy for Real Bipolar VSC-MTDC Transmission System

At present, voltage source converter based multi-terminal direct current (VSC-MTDC) technology has been widely applied. In the real bipolar VSC-MTDC converter station, the converters of positive and negative poles can be controlled independently. Firstly, in order to further increase the control flexibility of real bipolar VSC-MTDC system, the feasibility that stand-alone converters of positive and negative poles in the same converter station adopt different control strategies and the interaction effects are theoretically analyzed. Secondly, a multi-objective coordinated control strategy for real bipolar VSC-MTDC is proposed. In the same converter station, different control strategies are adopted in the stand-alone converters of positive and negative poles. In different system operation conditions, both the AC voltage stability and the active power consumption capacity of the bipolar DC system are improved by the corresponding coordinated pole-to-pole control method. Finally, the feasibility and validity of the proposed control strategy are verified in different operation conditions based on the real bipolar VSC-MTDC simulation system built on PSCAD/EMTDC.