中文摘要：

对基于电压源型换流器的多端直流输电（VSC-MTDC）系统在不同运行状态下的协调控制策略进行了研究。提出了改进的VSC-MTDC系统直流电压—有功功率控制特性曲线,在现有定有功功率控制的调节特性曲线中增加了斜率控制和定直流电压控制,并基于此实现了系统的协调控制策略;推导了环网式接线的VSC-MTDC系统正常运行时各换流站直流侧电压与所传输直流功率的关系式,并给出了各换流站直流电压—有功功率控制特性曲线中拐点处直流电压的计算方法。最后,在PSCAD/EMTDC中分别对不同运行状态下的VSC-MTDC系统进行了仿真,仿真结果表明,该协调控制策略能够满足系统在不同运行状态下的运行要求。

英文摘要：

This paper studies a coordinated control strategy of voltage source converter based multi-terminal high voltage direct current（VSC-MTDC） under different operating conditions.The improved direct current（DC） voltage-active power regulation characteristic curve of the VSC-MTDC system is proposed,the slope control and DC voltage control mixed in the existing characteristic curve,and the coordinated control strategy implemented based on the improved characteristic curve.When the ring net-wiring VSC-MTDC system is operating in steady state,the relationship between DC voltage and active power of each converter is derived,and the calculation method of the DC voltage at the inflection point of the DC voltage-active power regulation characteristic curve is given.Finally,simulations are performed in PSCAD/EMTDC to verify the validity of the control strategy under different operating conditions.Simulation results show that the coordinated control strategy can meet the requirements when the VSC-MTDC system is operating under different conditions.