| The traditional protective configuration of distribution substation is distributed protection,which is for the interval and more reliable.But there are several problems,such as repeated configurations,complex wiring connections,high cost,difficult information sharing,deficient whole coordination and functional optimization and high cost of operation and maintenance.While based on the information of overall voltage and current information and switch status in the distribution substation,centralized protection system can not only realize the existing protection function,but also develop new algorithms and protection functions to perfect protection function and improve protection performance.In this paper,the centralized protection scheme,hardware and software designing are researched based on the centralized protection device,mainly including 4 aspects.(1)Analyze the structure of distribution substation,operation mode and its existing problem and shortage of the distributed protection that is difficult cooperation between every protection due to small short-circuit current difference value between incoming and outgoing lines and long duration of protection action due to isolating bus fault by the incoming back up protection.(2)Put forward the centralized protection scheme and analyze the composition and protective logic to realize the protection functions distribution of the total station,including feeder protection,bus protection,distribution transformer protection and reserve power supply.And it overcomes the defect of difficulty of cooperation and long duration of bus protection.So the scheme can optimize function and improve protection performance.(3)An implementing scheme of hardware and software system of centralized protection device is proposed.Hardware system mainly includes CPU,transformer and relay module and software system includes the main program flow,protection logic and task process designing.(4)The total station protection function is realized in the centralized protection prototype,including over current protection,three phase one-time reclose,and reserve power supply.Each protection function module can correctly identify and instantaneously clear fault and bus fast protection can shorten action time from 1.358s to 0.059s to significantly improve the protective rapidity and selectivity.The scheme is correctness and feasible by the physical simulation test.The scheme of the centralized protection and hardware and software designing can make up for the difference of the traditional distributed protection.It applies to various distribution substations because of its simplicity and reliability and it is conductive to improve the reliability of power supply and reduce the running cost. |
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