Study On Power Grid Wide Area Backup Protection Algorithm With High Fault-Tolerance Performance

With the extensive use of technologies on wide area synchronized phasor measurements, information resources used by protective relaying system become more abundant. Wide area backup protection system collects spacial multi-point information, and makes integrated decision through intelligent optimization and information processing technology, without sacrificing movement time to ensure selectivity. It can isolate the fault quickly and minimize the blackout zone.The basic principle of the power system wide area backup protection is described in detail in this paper. Working characteristics, advantages and disadvantages in three common used structure of wide area backup protection system is analyzed. Wide area backup protection algorithm base on fault component judgment and its fault-tolerance performance are emphasized, which lays the foundation for the further proposed wide area backup protection algorithm with high fault-tolerant performance.Based on the research idea of using wide area information as little as possible to realize simple and reliable fault criterion with high fault tolerance, a wide area backup protection algorithm for power grid based on correlation matrix is proposed. It identifies the faulty component by summing each row elements values and comparing with a threshold value. Both enumeration method and Monte-Carlo method are used to study the fault-tolerance performance of the proposed algorithm for IEEE5-generator14-bus system. The results show that the proposed algorithm is simple and reliable with good fault-tolerance performance.Wide area backup protection collects wide area redundant information to improve the fault tolerance performance. If the information type and quantity is increased blindly, which increases redundancy also brings more error message. So it is difficult to decide whether the fault tolerance performance rises. On this background, a wide area backup protection information selection method is proposed in this paper. To quantify fault-tolerance performance of the algorithm, tolerance factor(TF) is mentioned. A method to select optimal information for the target to reach the maximum of tolerance factor is proposed. By analyzing the difference value of expected action for each type of protection. the maximum of tolerance factor and optimal protection information can be obtained.