Study On Fault Location Algorithm Using Dual-terminal Electrical Information Based On Longitudinal Impedance

The high voltage line is responsible for the transmission of electrical energy.At the same time,it is also the place where the most faults occur in power system.The precise location of high-voltage transmission line fault helps to rapidly eliminate the fault and repair transmission lines in time to ensure the security and stability of the power system.After in-depth research on the fault location algorithms,a new algorithm using two-terminal electrical information is proposed in the paper.The core idea of the proposed algorithm is from the longitudinal impedance.The longitudinal impedance is constructed in the R-L model of transmission line.It maintains a stable linear relationship with fault distance.Moreover,the three phase line is decoupled by the longitudinal impedance,obtaining a universal single-phase line model.Based on the longitudinal impedance,the expression of fault distance is derived in the R-L model of single phase line model.And the related electrical quantities are ensured stability and accuracy through analysis of the characteristics of the expression.Then the expression of fault distance is obtained in the R-L model of three phase line and the accurate fault distance is calculated.However,the fault location method above doesn't take the influence of distributed capacitance into account so that it is only applied to short lines.To long distance transmission lines,the influence of distributed capacitance cannot be overlooked.The P-equivalent line model is constructed in the general model.According to the fault location method above,the new fault location method is derived.To extremely long line,the precision of it also can decrease.Take an advantage of correction coefficient method from distributed parameter line model,the line parameters are modified.The P-equivalent line model constructed through the modified parameters not only has the feature of accuracy of calculation in the distributed parameter line model,but also has the characteristics of convenience of calculation in the lumped parameter model.And the precision is improved further.A large number of simulations are executed in the distributed parameter line simulation model reflecting the true state of the system by EMTP-ATP software.The simulation data are processed by MATLAB software.The simulation results show that the novel dual-terminal electrical variables fault location algorithm based on longitudinal impedance is not influenced by fault resistance?fault type? fault position and variation of operating mode for power system.The algorithm is more practicality in engineering.