适合风电接入的VSC-MTDC系统协调控制策略

对于具有小集中、大分散特点的内陆风电,交流并网存在电能质量下降、经济性差等诸多问题,两端柔直并网也无法满足要求。使用多端柔直是未来风电并网的发展方向,文中提出一种适合风电接入的多端柔直系统协调控制策略。该策略综合考虑直流电压改变的方向、电压改变的大小以及换流站功率裕度等因素,自适应实时调节下垂系数,优化换流站之间功率分配,避免不当下垂系数造成的系统损耗增加、部分换流站功率过载。引入附加频率控制与自适应下垂控制协调,可充分利用系统调频容量,改善系统频率稳定性。控制器参数易于整定,结构简单。在PSCAD/EMTDC电磁暂态仿真软件中搭建了嵌入多端柔直系统的四机两区域模型,验证了所提策略的有效性和可行性。

Coordinated control strategy for VSC-MTDC systems with wind power integration

For inland wind power, there are many problems with AC interconnection, and the double terminal voltage source converter based high voltage direct current(VSC-HVDC)system can not satisfy the requirements. Multi-terminal VSC-HVDC(VSC-MTDC)is the tendency of wind power integration. The coordination of adaptive DC voltage droop control and HVDC additional frequency control was proposed. The droop coefficient varies adaptively according to the value and direction of DC voltage change and the power margin of the converter station, optimizing power distribution between converter stations. And the additional frequency control is introduced into VSC-MTDC. Takeing full advantage of frequency adjustment capacity. Controller parameters are easy to set and simple. The simulation results show the effectively of coordinated control strategy.