新型电力系统背景下西部送端直流电网及系统运行特性

Sending-Terminal DC Power Grid in Western China and Its Operation Characteristics in the Context of New Power System

新型电力系统背景下,未来中国面临着远距离、大容量西电东送的重大需求。基于柔性直流的团块状互联大型西部送端直流电网可以实现西部风、光、水、火等不同特性电源之间的互补调节,解决新能源出力的随机性和波动性问题。在研究直流电网的稳态模型、电磁暂态模型和协调控制策略的基础上,构建西部送端直流电网的仿真系统,分析西部送端直流电网的稳态运行特性和暂态运行特性,以及大规模新能源出力波动对直流电网运行的影响。结果表明,面对交直流故障扰动引起的新能源换流站功率变化以及天气原因引起的新能源出力波动,西部送端直流电网换流站之间可以进行功率协调,实现各类能源的紧急增援,降低扰动影响。因此,构建西部送端直流电网可以实现大规模新能源的远距离、安全稳定传输。

Inevitably China will encounter the enormous demand of large-capacity power transmission over long-distance transmission from the west to the east in the future.With regards to such emerging requirement,a cluster-connected western sending terminal DC grid based on VSC-HVDC is constructed in this paper such that the complementary regulation is performed between different power sources such as wind power,solar power,hydro power and thermal power in Western China,and the problem of randomness and fluctuation of renewable energy can also be addressed.The simulation system of the western sending terminal DC grid is set up based on the studies of the steady-state model,transient model and coordinated control strategy.Furthermore,the steady-state operation characteristics and transient operation characteristics of the western sending terminal DC grid are analyzed,as well as the impact of large renewable energy generation fluctuation on the operation of DC grid.The results show that,in view of the power change of the renewable energy converter stations caused by AC/DC fault and power fluctuation due to the weather reasons,power generation can be coordinated among the converter stations to achieve emergency backup of all kinds of energy sources and reduce the disturbance impact.Therefore,the western sending terminal DC grid can realize the stable long-distance transmission of large-scale renewable energy.