计及柔性直流的城市电网多源无功控制及短路电流修正策略

Multi-source Reactive Power Control and Short-circuit Current Correction Strategy for Urban Power Grid Considering VSC-HVDC

城市电网存在着供电能力有限、无功储备不足等问题,合理的接入柔性直流可以有效地缓解上述问题。在无功控制方面,提出城市电网多源无功协控策略,利用柔性直流动态无功调出迅速、灵活可控的优点,将柔性直流纳入城市电网传统无功支撑源(发电机、调相机、投切电容等)协调控制体系,充分发挥柔直暂态电压控制响应迅速、传统无功源稳态电压控制低成本优势,在实际电网仿真中验证控制策略的有效性。考虑柔性直流接入城市电网后可能带来的短路电流超标风险,针对现有的短路电流计算方法对柔性直流远端故障场景计算结果偏保守问题,提出一种考虑柔性直流接入影响的电网短路电流简化计算方法,满足城市电网远端故障时的短路计算精度的需求,支撑实际电网的短路电流工程计算。

There are a series of problems in urban power grids,such as limited power supply capacity and insufficient reactive power reserves.Concerning reactive power control,VSC-HVDC is incorporated into the coordinated control system of traditional reactive power support sources(generator,camera adjustment,and switching capacitor)of the urban power grid by using the advantages of VSC-HVDC dynamic reactive power transfer in a fast and flexible way.The advantages of the fast response of flexible direct transient voltage control and the low cost of traditional VSCs are fully exploited.A multi-source reactive power CO control strategy for an urban power grid was proposed,and its effectiveness was verified in an actual power grid simulation.Considering the risk of over-standard short-circuit current caused by VSC-HVDC connected to an urban power grid,the calculation results of the remote fault scenario of VSC-HVDC are conservative according to the existing short-circuit current calculation methods.This paper presents a simplified calculation method for short-circuit current considering the influence of VSC-HVDC access,which can meet the needs of short-circuit calculation accuracy in the case of remote faults of urban power grids and support the engineering calculation of short-circuit current in actual power grids.