The Online Verification Of Backup Protection Based On Wide Area Measurement System

Conventional power system relay protection is equipped with master protection and backup protection. Conventional line backup protection makes judgments and decisions only basing on the local measurement information of electric components, without considering whether it will lead to the overload of other lines and cascading tripping. The operation mode of regional power network is flexible and variable while the setting values may not be able to meet the requirements when running in a particular operation mode. If that couldn't be detected and be adjusted, the unreasonable setting values may lead to the maloperation of protection and even large-scale blackouts.With the development of information technology and communication networks, wide area protection is proposed which not only provides component protection but also ensure the security and stability of power system. Wide area measurement system collects information of each point including electric measurements (voltage, current, etc.), network topology structure and operation information which is crucial to the implementation of wide area protection. Wide area measurement is mainly used in the backup protection whose setting delay gives it enough time to gather system information. This paper uses the measurement information to achieve the online verification of backup protection. For one thing, the online verification system of backup protection setting value can be started to verify the rationality of the setting values in current operation mode according to the real-time data including switch state and load value when detecting the change of operation mode. For another, it can use the real-time data to calculate whether cutting off the overload line will lead to the cascading tripping when detecting the line has been overload.The"online verification of backup protection based on wide area measurement system"designed in this paper achieves the module of forming the fault sets based on the online verification rules, setting calculation module and most of the simulation verification module. Besides, the paper proposes the algorithm of judging the cascading tripping based on wide area measurement information and describes the control strategy and method of using this algorithm in wide area backup protection in detail. The simulation result shows that the algorithm and program proposed in this paper are correct and effective.