Wide-Area Backup Protection System Based On Fault Direction Information

The drawbacks of traditional relay is the following: the protection are not well adaptedflexible operation mode because of offline setting calculation, and with the power structureis large and complex increasingly, the co-ordination between protection of setting valueand operating time are more complex, which increases the workload of setting calculation,protection co-ordination may exist die may. With digital substation technology and widearea measurement technology developed and consummated continuously, wide-area backupprotection came into being. the so-called wide-area backup protection is that usesmulti-point information of power system for fault identification, which aims to improve theshortcomings following the traditional electrical protection, with the traditional relayprotection to ensure safe and reliable operation of power systems.As the power network topology becomes more complex and operation becomes moreflexible, the shortcomings of traditional relay protection gradually exposed, its reliability isseriously threatened. With digital substation technology and wide area measurementtechnology developed and consummated continuously, using the new configurationprinciple and constitution principle, wide-area backup protection, aimed at improving thedrawback of traditional backup protection, as the times require. It uses the moreinformation of power system to achieve wide area protection function, to solve thedrawback of traditional relay protection, and cooperated with the traditional relayprotection to ensure the safe and stable operation of power system.At present, the information used by wide-area backup protection can be divided intotwo categories: one is the electric information as voltage and current gathered directly fromthe power grid, then wide-area backup protection carries out real-time on-line settingcalculation; the another is the logic of information as protection and circuit breaker state,the wide-area backup protection does not need to carry out the traditional meaning ofsetting calculation when using these information. This paper mainly uses the latter toconstitute the wide-area backup protection scheme.Since the reliability of a single logical information is not high, a project is proposed to use the action information of distance relay and direction relay information to achievewide-area backup protection fault recognition. Based on the topological structure of powergrid to compose correlation matrix, and then to realize fusion of the two kinds information,so the circuit breaker with distance relay action information and different direction relaymovement information. When a component information is missing or wrong cases in acircuit breaker, there still exists other information which can identify the fault components,simulation results verify the feasibility of the project.