Study On Enterprise Power Supply Network Area Protection

In our country, enterprise power supply network uses6~35kV voltage levels,andsubstations plus switching station or cascade the switching station supply often, multi-usecable into the outlet, the length is short and load density is high. When the large grid whichaccessed run in large and small operation mode, there is a big difference betwen theirShort-circuit current,will Lead the traditional three-stage protection can’t correctly identifythe fault location, and Can’t remove the fault properly. Specific performance: Noinstantaneous trip protection range, protection loss Selective and so on. Traditionalprotection is difficult to guarantee the reliability of enterprise power supply, affect the safeproduction seriously. Therefore, Urgent need for a new type of protection, to solve theProtection problems exist in enterprise power supply network.Thesis research gives the area centralized protection system architecture, based on theresearch enterprise supply network characteristics and domain protection principle. Enterprisesupply network is divided into several limited areas, Each power outgoing line in the maintransformer station as a partition. Set up a special region protection center in each area,Communication with the IED in jurisdiction, to receive the information IED upload about thefailure and preliminary calculations, reported the results to the control center, the controlcenter determine the fault location combined the system topology get the tripping strategy.Expansion Wavelet analysis in selected lines combined the characteristics of enterprise supplynetwork, region protection center selected lines for each bus in jurisdiction independently first,from the power source the control center choose the fault area base on the result of regionprotection center second, at last control center combined the zero sequence current waveformcharacteristics of the bus incoming line in the area which Selected to find the fault location.Description the algorithm by a examples and verify the accuracy of the algorithm by anotherexample.The Domain protection algorithm is simple and reliable, can identify the various faultcorrectly in Enterprise power supply network, lay a foundation to slove the over level tripping and expansion wavelet analysis into area protection.