Research On Wide-area Relaying Protection Algorithm Based On Fault Element Identification

With the development of power grid, by using local information the traditionalback-up protection has drawbacks such as setting difficulty, long time delay, lack ofself-adaptation and hidden failure. Recently, protection relaying based on wide-areainformation, namely wide-area relaying protection, provides an opportunity to improveperformance of traditional protection. Fault element identification is a proper approach torealize the functions of wide-area relaying protection. With this approach, selectivity can besimply guaranteed by time and logic coordination with no setting calculation. Operationtime can be also reduced and flow diversion in a wide scope will not lead to cascadingoperations. Fault element identification algorithm base on wide-area information is focus ofstudy up till now.Fault element identification algorithm includes study of basic principle as well aserror-tolerant algorithm based on multi-source information fusion. Their major points ofstudy and key issues during engineering applications are discussed. On that basis, severaltypical fault element identification principles are analyzed with simulation tools and furthercompared. Their respective advantages and disadvantages are discussed and some solutionsare recommended, to help develop new algorithms and perfect existing ones.With the property of fast operation, current differential protection is one of the mainwide-area relaying protection fault identification approach. However, its largecommunication traffic reduces the efficiency of communication channel. Considering thatinformation redundancy of current signals is different when current magnitude varies, acurrent differential protection improvement algorithm based on re-quantitativemeasurement signals is proposed. Quantization codes are directly used in the improvedcurrent differential protection. The method can decrease communication traffic withoutperformance degradation.Considering that reliability of fault identification decreases in consideration ofinformation acquisition and communication within wide-area., multi-source informationfusion can be adopted to improve the information fault-tolerant capacity. A fault elementidentification algorithm based on binary particle swarm optimization is proposed. Digitalprotection information within limited fault section is used to build an optimization model for fault element identification. The algorithm has high convergent rate and is adaptive tooperation mode.