The Checkout And Simulation Of The Relay Protection In Industrial Electric Power Systems

With the fast development of power system, the scale of electrical network expandsconstantlyanditalsorequireshigherandhigherperformanceofrelayprotection.Whethertherelay protection operates correct is very important for the safety operation of powerequipmentandthestabilityofthepowersystem,atthesametime,someresultsalsoindicatedthat almost all of the large-scale faults have some direct or indirect relationship with themaloperation of relay protection, so it is an exact work to checking the parameters of therelayprotectionduringthefault.This paper mainly discussed the protection of the generators, based on the fault ofTianjin petrifaction thermoelectric factory in 2000.6.14. First, we got the information of thekinds and set value of generators'protection though the investigation, chose the protectionswhich operate incorrectly easily during the fault to study based on a lot of materials, that isover-current protection and the loss of excitation protection. And then the model of thepetrifaction thermoelectric factory was set. The simulation was divided into two parts:without control and with some controls to improve the stability of the system. For theover-current protection, short circuit and open circuit faults were chose. On one hand, weusedPSASPtosimulatesystem whenthefault occurred,thenworkedout whetherit operatedcorrectly. On the other hand, we counted the current value of the generator though theequivalence of the system to checking the protection. For the loss of excitation protection,first the factors which easilymade the loss of excitation protection maloperation were deeplyanalyzed, then the checking work was worked out in the system when the open circuit faultoccurred. In the last part of the paper the conclusions were shown that the over-currentprotection and the loss of excitation protection of the generator at present wasn'tmaloperation when the open circuit fault occurred in the outward system. When the shortcircuit fault occurred, the over-current protection would operate incorrectly, so the control ofit shouldbeimprovedand theloss of excitationprotectionshouldberesearcheddeeplyinthefuture.