雷击工况下UHVDC线路行波保护误动概率模型与风险评估

Probability Model and Risk Assessment of False Tripping of Traveling Wave Protection on UHVDC Transmission Lines Under Thunder Strike

特高压直流线路行波保护存在雷击工况下的误动风险,而简单提高定值会带来高阻接地时的保护拒动风险.针对该问题,文中提出以线路落雷率、绕击率、波头参数分布概率和考虑雷击位置的行波保护误动区间等参数构成雷击工况下特高压直流线路行波保护的误动概率模型,根据叠加原理计算误动概率,结合雷电活动数据求取误动频率,并以上述两项指标实现对行波保护的雷击误动风险评估.最后以南方电网某特高压直流线路为例,利用实际参数与录波结果对文中方法进行评估,所得结果与实际工程统计结果相符.

There exists a false tripping risk in the traveling wave protection on UHVDC transmission lines under thunder strike,and simply increasing the set value may cause an action failure when high resistance earthing happens. In order to solve these problems,a probability model to analyze how the traveling wave protection falsely trips on UHVDC transmission lines under thunder strike,is constructed by using the parameters including the thunderbolt rate on transmission lines,the shield failure rate,the distribution probability of wave fronts and the false tripping section of traveling wave protection on the basis of thunder strike location. Then,malfunction probability is calculated on the basis of superposition principle,and malfunction frequency is obtained from the data of lightning activity. Furthermore,by adopting the two indicators,the risk assessment of the false tripping is performed. Finally,by taking a UHVDC transmission line of China Southern Power Grid as an example,the proposed method is verified by using both actual parameters and wave recording data,finding that the results accord well with the practical engineering statistics ones.