采样及对时网络异常场景下线路/区域主保护动作行为分析及优化应对策略研究

In order to guarantee the security of protection operation, the flawed packets from sampling network are generally abandoned intentionally. Yet this conservative treatment would result in an indeed short blocking of the line differential protection, which is commonly recognized as the protection with the best performance. Nevertheless, with the development of networking trend of protection, there still exist quite a few mal-operation or fail-to-trip accidents due to sampling and/or time synchronization network abnormalities in recent years. In order to tackle this problem, new requirements should be put forward to the protection design in response to sampling network and synchronizing system abnormalities. It is necessary to specifically analyze the individual effects of various communication system abnormalities on the unit main protection, and with the introduction of various advanced theories such as state-space method, a series of new protection concepts and principles capable of coping with different abnormal scenarios such as local information synchronization quality deterioration, completely losing of synchronization, communication network congestion and even losing the whole substation sampling information should be proposed. This project focuses on the comprehensive enhancement of the four properties of protection in the case of sampling and time synchronization network abnormalities. To achieve this, the behavior of line differential protection during these abnormalities should be analyzed, and improved strategies of line unit main protection in the case of local information deterioration or losing, as well as the wide-area emergency protection strategy in the case of whole substation sampling information losing, should be studied. Also, the verification methods of line & region main protection improved strategies in the case of sampling and time synchronization network abnormalities should be developed. Totally, a series of fundamental concepts and key technologies of protection coping with sampling and synchronizing network abnormalities will be systematically proposed in this project.

为保障保护的安全性，当前对瑕疵数据包常采用主动丢包的方式，这种保守的处理会导致差动保护短时闭锁，事实上造成线路短时失去性能最优的主保护。即便如此，在保护网络化的大趋势下，近年来仍出现多起采样及对时网络异常导致的保护误拒动事件。这种局面对站内网络异常场景下的保护应对策略提出了新的要求：需要针对性分析各种通信异常对线路单元式主保护的差异化影响，引入包含状态空间法在内的先进理论，提出能应对局部信息同步品质劣化、完全失同步以及通信网络拥塞乃至全站采样信息缺失场景下的保护新原理。本项目以全面提升应对采样及对时网络异常场景时的保护四性为着眼点，分析该场景下的线路差动保护动作行为，研究局部信息劣化或缺失场景下的线路单元式主保护优化策略、全站信息缺失场景下的广域化应急保护策略，以及基于上述研究所形成的线路/区域主保护优化应对策略的测试验证方法，系统性提出应对采样及对时网络异常场景的保护基本理论和关键技术。

随着变电站的深度信息化、网络化成为必然，变电站的各类保护将越来越依赖于通信网络，必须提出切实可行的方案来解决采样及对时网络异常问题对于变电站保护的影响。为此本项目分类研究了各种采样网络及对时系统异常下的保护动作行为，围绕采样及对时网络异常场景下线路/区域主保护动作行为分析及优化应对策略进行研究。.针对局部信息劣化或缺失的场景，提出了一种适用于超/特高压交流输电线路的基于贝瑞隆模型的高灵敏度双K值差动保护新判据，使判据动作区域不缩小的前提下相移耐受能力提升至60°。.针对站间完全失同步的问题，提出一种基于故障分量瞬时功率相空间轨迹识别的线路纵联保护新判据，同步对时误差达到20ms时仍能可靠不动作。提出一种新的基于特勒根似功率定理的纵联保护方案，完全不受同步异常以及线路分布电容的影响；提出基于和阻抗继电器原理的模量保护判据和中段保护判据，对于金属性故障，基本做到无死区。针对SV丢包的场景，提出了临近信息重构的线路单元式保护新原理、基于状态空间信息熵的纵联保护新原理等，对于某一路环节采样发生异常且过渡电阻不高于150Ω时仍然能可靠保护线路全长。.针对全站信息缺失的场景，提出了可适应同步品质劣化的广域差动保护启动新判据，判据相移耐受能力能达到95°；对于保护采样网络同步性得到保障的场景，提出了中压变电站二次系统性能提升方案及远方冗余保护新判据，使得金属性故障短路时保护盲区降至5%以下。.除此以外，本报告还进行了电流互感器采样环节异常及精度受限情况下的保护原理优化；提出了基于双曲正切函数动作特性的集电线路反时限保护方法、基于站域信息的动态电压补偿反时限保护优化方案、考虑TCSC型故障限流器动态过程的距离保护整定方法等多项新原理和新方案。本项目的研究成果系统性的提供了应对采样及对时网络异常场景的保护基本理论和关键技术。