交直流混联电网中交流暂态侵入对直流继电保护的影响分析

Influence Analysis of AC System Transient Invasion on DC Protective Relaying in AC/DC Hybrid Power System

为减少交流系统故障情况下直流继电保护误动作事故的发生,引入交流暂态侵入(IAST)的概念,为交直流混联系统中直流继电保护的设计与运行提供新的视角。首先分析了IAST及其暂态响应的机理、形式、特征等。在此基础上,分析了IAST给直流继电保护带来的问题和挑战。结果表明,IAST使得换流器区保护与换流变压器区保护之间的权责不清,导致以100 Hz保护为代表的直流保护与交流保护之间的时序配合不当,影响到直流保护的动作定值与性能。在保证直流输电系统一次设备安全的前提下,可通过改进保护逻辑、优化定值等手段,最大限度地提高交直流混联系统的运行效率和可靠性。

In order to reduce the mal-operation of DC protective relays caused by AC system faults, we put forward a concept called the invasion of AC system transients（IAST）, and provided a new way for the design and operation of DC protective relays. Firstly, we clarified the mechanisms, forms, and characteristics of IAST and its transient response. Thereby, we analyzed the problems and challenge faced by the DC relay protections caused by IAST. The results show that the division of labour between the converter and the converter transformer protections is not clear due to IAST, and the sequences coordination between the DC protection（represented by 100 Hz protection） and AC protection is mismatched, affecting the action constant value and performance of DC protection. However, on the premise that the DC transmission primary equipment is safe, we can maximize the efficiency and reliability of AC/DC hybrid power system through improving protection logic and optimizing protection threshold, etc.