Fault Location Of Transmission Line Based On Immune Algorithm

Ultrahigh voltage and its transmission lines bear the role of long distance transmission of electric power.It has the advantages of long transmission distance,less power loss and large transmission capacity.If the faults of ultrahigh voltage and extra-high voltage transmission lines will not be wliminated in time,the economic losses and social impacts will be enormous.Therefore,the fault type identification and fault location of ultrahigh voltage lines are of high application value.It is of great significance to determine the fault location in time to ensure the reliable and safe operation of the power system.At present,the main methods of fault location includes traveling wave method,fault analysis method and intelligent distance measuring method.After comparing and analyzing,this paper chooses fault analysis method for fault location.It is the first step of fault location to classify the fault types of ultrahigh voltage and extra-high voltage transmission lines.The PSCAD software is used to simulate the line fault,and the voltage and current waveform of different position,fault type and fault resistance are obtained.The three phase current and zero sequence current are used as the fault characteristic quantity,and the wavelet transform fault characteristic quantity is used to extract and normalize.Then it is analyzed and processed with the improved immune algorithm,and the fault classification results are obtained.Verifying the results of fault classification,it can be concluded that the improved immune algorithm has a high accuracy on fault classification,and the speed of calculation is faster,which can meet the requirements of the project.The parameters of transmission lines are not fixed values,and the line parameters need to be taken into account in the fault location equations.So the fault location equations become a nonlinear equation.If the initial value is obtained by improved Newton method in the case of large nonsynchronous angle of double-end system can not guarantee the astringency of Newton iteration method,which leads to the failure of the distance measurement.The global search ability of the simulated annealing algorithm is used to optimize the nonlinear equations,and the optimization results will used as the initial value of the improved Newton equation.Simulated annealing and improved Newton method are used to verify the fault location results,and the accuracy of computing can meet the engineering requirements.