柔直联于弱交流系统分析和仿真试验研究

System Analysis and Simulation Experimental Research of VSC-MMC HVDC Connected to AC Weak System

首先对柔性直流输电工程接入交流弱系统的控制性能进行了分析,然后分析了接入弱交流电网的柔直系统在不同控制方式下的性能。依托渝鄂背靠背柔性直流工程,对渝鄂柔直北通道渝侧弱系统方式进行了系统计算分析,根据系统计算分析结果,提出了构建“接入系统强度管理装置”用于保证渝侧在接入弱系统方式下能够稳定运行,提高了设备可用率和年运行可靠性、减少直流强迫停运次数,对运行维护具有重要意义。应用RTDS实时仿真装置建立了实时仿真系统,对接入弱系统方式下柔直控制保护策略进行了验证,该策略已经在渝鄂背靠背柔性直流工程得到了应用,保证了渝鄂柔直在弱系统方式下稳定运行。

Firstly,the control performance of the MMC-HVDC transmission project connected to the weak AC system is analyzed,and the performances of such a system under different control modes are illustrated.Relying on the Yu(Chongqi city)to E(Hubei province)back-to-back MMC-HVDC project,the weak system operation mode on the north channel at Yu side is calculated and analyzed.Based on this system calculation and analysis result,the"system strength management unit access"is proposed to establish in order to ensure the stable operation of the system at Yu side under a weak system access mode,which improves the equipment availability and years of operation reliability,reduces the times of the MMC-HVDC converter station forced shutdown,a great significance for operation maintenance.A real-time simulation system based on the RTDS real-time simulation device is established and the weak system access mode under the soft control protection strategy is verified.The strategy have already been applied on the north channel of the Yu to E MMC-HVDC back-to-back project,and it has guaranteed the Yu to E back-to-back project stability operation under the weak system mode.