Analysis And Simulation Of Fault In Power Electric System Based On PSASP

Power system failure will endanger the safety of important users,and at the same time,the transient response of the fault will also have adverse effects.Short circuit is the most common fault of the power system.Calculating the short circuit current is an important content in the power system calculation and analysis,and the results are of great significance to the safe and stable operation of power system.It provides an effective means for the selection of electrical equipment,setting relay protection and accident analysis in the planning,design and operation of power system.Removal of large load failure have a great influence on the power system,in severe cases,the failure of a large load will result in a qualitative change in the results.Through the analysis of the removal of large load,it will be helpful to the construction and planning of the power grid.Open circuit fault also named longitudinal fault.When the asymmetric fault occurs in the power system,although it does not cause a sharp drop in the short circuit current and voltage,it will produce large negative sequence current and zero sequence current.Negative sequence current causes the generator winding to overheat,zero sequence voltage interferes with communication system,and the asymmetry voltage and current they caused may result in certain disoperation of relay protection.Therefore,fault calculation is very important for the design and safe operation of power system.This paper simulates three cases that short circuit,open circuit and large load removal of power system,and analyzes the results,the aims are familiar with the phenomenon of failure,and take effective measures to timely restore system power supply.Firstly,this paper analyzes the principle of short circuit calculation,and studies the calculation method of three-phase symmetrical short circuit and asymmetric short circuit.Power System Analysis Software Package(PSASP7.0)is used as a simulation and calculation tool.Four kinds of short circuit faults are set up based on the power flow and the project,which are three phase short circuit fault,two phase short circuit fault,two phase short circuit fault and single phase short circuit fault.And the fault data are compared and analyzed.Then,it is concluded that the short circuit calculation based on power flow is more accurate.After changing the initial value of power grid,we found that the variables have little influence on the short circuit current.Secondly,this paper presented the fault analysis of heavy load removal of power system.Establish the load model by figure model integration platform of PSASP.Removing the different loads,and then,calculating these data that active power,reactive power,bus voltage amplitude,phase angle of voltage and generator active power,reactive power,and power factor by load flow calculation.Based on the comparison of the data,we analyzed the effect of large load removal on power system.Finally,this paper analyzes the open circuit fault of power system.Us the symmetrical component method to decompose the network into three symmetric sequence networks that is positive sequence,negative sequence and zero sequence.Calculate the Thevenin equivalent circuit.Analyzing and calculating the phase voltage and phase current in the case of one phase and two phase open circuit fault.Draw a single line diagram of figure model integration platform of PSASP.Finally,under the normal operation of the system,simulating the open circuit fault of different lines,and comparing the fault data obtained from the disconnection.