Research On Optimal Coordination Of Definite Time Relay And Its Application In Online Setting Calculation System

Since years ago, with the grid scale expanding extremely fast and the frequentchanges of the operation mode, the disadvantages of traditional setting calculation modebecome more and more serious. For the purpose of improving the performance of relaysettings, it is very important to research on optimal coordination of relays and adjustsettings according to the real-time mode of power systems. To solve above problems, thispaper has researched optimal coordination of definite time relay and its application inonline setting calculation. The main contents are as follows:The research development of optimal coordination of relay settings by academiccircles home and abroad is surveyed. Existing optimization models are summarized fromthree aspects of inverse time relay, definite time relay and mixed relay protection, whileoptimization algorithms are from aspects of mathematical programming methods andintelligent optimization algorithm. On this basis, the problems to be deeply studied aboutoptimal coordination of relay settings are pointed out, which lays the theoreticalfoundation for further research in this article.The thesis analyses optimal coordination of relay settings from the point of view ofrisk, and then constructs a mathematical model of optimal coordination of definite timerelay settings based on risk indicators. Considering both uncertainties of power grid andthe consequence of line failure, the thesis defines "generalized relay action time" as therisk indicator and optimizes with the purpose of minimizing the risk indicator. Accordingto the presented method, the thesis adopts GA to solve the modal. Simulation resultsshow that the model can effectively reduce operational risks and improve theperformance of relay settings, which is conducive to ensure the safe and reliableoperation of power grid.Finally, the thesis discusses the application of definite time relay optimalcoordination in online setting calculation system. After outlining the structure of relay setting online verification and calculation integrated system, a method of online optimalcoordination considering higher limit settings is proposed. In this method, the onlineoptimal range is quickly determined through searching of concentric relaxation. By theway of considering higher limit settings and optimizing by GA, online relay settingoptimization is achieved.