摘要
基于模块化多电平换流器的高压直流电网作为支撑高比例可再生能源接纳的有效手段,已经成为电网发展的重要方向。双极短路故障是输电线路发生的最严重故障,目前一般通过在s域内列写直流系统状态方程,然后再基于拉氏反变换求解故障电流,亟待提出短路电流的工程实用计算方法。为此,以张北柔性直流电网为研究对象,首先分析了输电线路双极短路的故障特性及耦合机理。在此基础上,将故障线路靠近阀侧的两端分别看作二端口,分析了故障电流与二端口两侧电压的关系。其次,基于正、负极线路二端口电压变化不大的思想,将环形直流电网简化为两端网络或开式网络,得到故障线路电流的实用计算方法,不再需要求解高阶的拉氏反变换而直接得到故障电流。最后,通过与电磁暂态仿真结果的对比,验证了实用计算方法的可行性与高效性。
As an effective means to support the adoption of high proportion of renewable energy, modular multilevel converter based high-voltage direct current(MMC-HVDC) has become an important development direction of power grid. The bipolar fault is the most serious fault in transmission lines. At present, state equations of DC system are usually written in s-domain, and then fault currents are solved based on the inverse Laplace transformation. A practical engineering calculation method for fault current is needed urgently. Zhangbei MMC-HVDC grid of China is taken as the research object, the fault characteristics and coupling mechanism for bipolar fault of transmission line are analyzed firstly. On this basis, the two ends of the fault lines near the valve side are regarded as two ports respectively, and the relationship between the fault currents and the voltages of the two ports are analyzed. Secondly, based on the idea that the voltage of the two ports of the positive and negative lines does not change too much,the annular MMC-HVDC grid is simplified to a two-terminal network or an open network. The practical calculation method of fault line current is obtained to calculate fault current directly, while it is no longer necessary to solve the high-order inverse Laplace transformation. Finally, the feasibility and efficiency of the practical calculation method are verified by comparing with the electromagnetic transient simulation results.
作者
郝亮亮
李伟杰
王卓雅
顾亚旗
王光
HAO Liangliang;LI Weijie;WANG Zhuoya;GU Yaqi;WANG Guang(School of Electrical Engineering,Beijing Jiaotong University,Beijing 100044,China;NR Electric Co.,Ltd.,Nanjing 211102,China)
出处
《电力系统自动化》
EI
CSCD
北大核心
2020年第5期68-76,共9页
Automation of Electric Power Systems
基金
国家重点研发计划资助项目(2018YFB0904600)。
