含限流电抗器的环形直流微电网暂态对地高频电压保护方法

Protection Method for Transient High-frequency Voltage-to-ground in Ring DC Microgrid with Current Limiting Reactor

直流线路保护是直流微电网技术发展的关键,限流电抗器为直流故障保护算法的设计提供了便利。针对含限流电抗器的环形直流微电网,利用限流电抗器的故障暂态高频电压特性,提出一种基于限流电抗器两端对地高频电压的保护方法。该方法利用故障后线路两侧限流电抗器两端对地高频电压的差异性识别区内外故障,对于线路背侧阻抗呈容性将导致保护无法正确动作的情况,通过选择合适的频率能够很好地解决。仿真结果表明,该保护方法可快速、准确地判断故障线路和故障极,灵敏度与可靠性高,阈值易设定且无须相邻线路保护配合,对双端数据同步要求较低。该方法在不同的故障场景和运行方式下均能可靠进行故障识别和故障选极,并且耐受过渡电阻能力较强。

DC line protection is the key to the development of DC microgrid technologies.Current limiting reactor provides convenience for the design of DC fault protection algorithm.Aiming at the ring DC microgrid with current limiting reactor,this paper uses the fault transient high-frequency voltage characteristics of current limiting reactor to propose a protection method based on the high-frequency voltage-to-ground at both ends of current limiting reactors.The method uses the difference of high-frequency voltage-to-ground at both ends of current limiting reactors on both sides of the line after a fault to identify the internal and external faults.For the situation where the capacitance of the impedance on the back of the line will cause the protection to fail to operate correctly,selecting an appropriate frequency can effectively solve the problem.The simulation results show that the proposed protection method can quickly and accurately identify the fault line and fault pole with high sensitivity and reliability,easy threshold setting,no need for cooperation of adjacent line protection,and low requirements for the double-terminal data synchronization.The proposed method can reliably perform fault identification and fault pole selection in different fault scenarios and operating modes,and has strong ability to withstand the transition resistance.