Research On Equivalent Double-end Fault Location Technology Of Multi-type HV Transmission Lines

The high-voltage transmission line is the key link for transmitting electrical energy in the power system.It's safe and reliable operation is the basic condition for ensuring the power supply and an important guarantee for the stable development of the national economy.Fault location of transmission lines is an important means to promote the safe and stable operation of the power grid.Considering economic factors,transmission line corridors,floor space,and power supply requirements,the structure of the power system is becoming more and more complicated.Type structure line.Compared with a single three-phase transmission line,fault location of multi-type structure lines is more difficult,and further research is necessary.This paper summarizes different fault location algorithms for multi-type transmission lines.Based on the actual engineering application,based on the distributed parameter model,the traditional single-circuit transmission lines,T-type transmission lines,and non-full-length double-circuit transmission lines on the same pole are compared.The ranging principle has been studied systematically.The main work of this article is as follows:1)Aiming at the double-end fault location method for single-circuit transmission lines,a fast fault location algorithm based on cross-voltage correction along the line is proposed.Based on the distributed parameter model,the distribution of the voltage amplitude along the line calculated on both sides of the line is analyzed.The voltage distribution along the line tends to coincide during out-of-zone faults,while the voltage distribution along the line during inter-zone faults only intersects at one point.Furthermore,it is proposed to use the measured values on both sides of the line to connect with the calculated values on the opposite side,to locate the fault based on the principle of straight line crossing,and to achieve accurate fault location through a few iterations and corrections.2)Aiming at the problems of complex T-type transmission line fault location algorithm and the existence of dead zone,a T-line fault location algorithm based on parameter modification is proposed.When the line is in normal operation,the measured voltage and current are used,based on the distributed parameter model,genetic algorithm is introduced to dynamically calculate the transmission line parameters in real time to optimize the line parameters.Further use the three-terminal measurement voltage andcurrent of the T-type line to calculate the voltage at the T point respectively,establish the voltage amplitude and phase comparison criterion,realize the pre-judgment of the fault branch,and realize the T-type line based on the principle of straight line crossing through the equal value of the two ends of the fault branch Accurate fault location.3)Aiming at the difficulty of completely decoupling the fault location algorithm of double-circuit lines on the same tower with non-full-range,a step-by-step fault location algorithm based on "loop-section-point" is proposed.For the double-circuit coupling section,use the six-sequence component decoupling method and inverse transformation to calculate the T point voltage value.For the single-circuit section,use the distributed parameter model to calculate the T point voltage.Based on the voltage amplitude comparison criterion,the line up and down Predict the circuit.Based on the range where the voltage distribution point of the loop distribution is located,the section judgment of the single and double circuit lines is realized.Finally,by equating the two ends of the faulted branch,based on the principle of straight-line crossing,the precise fault location of non-full-length double-circuit lines on the same tower is realized.PSCAD software was used to build simulation models for different lines,and the proposed fault location algorithm was simulated and verified.The simulation results show that the proposed fault location algorithm is not affected by the transition resistance and asynchronous angle,and the location accuracy is high.