Research On Fault Location Technology Of Multi-Terminal Transmission Line With Wind Power

With the continuous development of the transmission network,special structure of transmission line appears in some transmission systems,especially in the secondary transmission system.Different from the traditional double-terminal transmission line which can only contact two terminals,teed transmission line can contact three terminals,and multi terminal transmission line can contact more terminals.The special structure of the transmission line saves resources needed for transmission lines,reduces the transmission cost,and then has important significance in the power system.However,when faults occur on the transmission line with special structure,the complex of the circuit topology also brings some difficulties to the determination of the fault section and fault location.Firstly,research on fault location of transmission line at home and abroad and fault location of transmission line with wind power are investigated in the paper.The specific traveling wave algorithm and impedance algorithm for multi-terminal transmission line fault location are analyzed and discussed.For teed transmission lines that will appear in the multi-terminal transmission line,the paper introduces a fault location algorithm based on distributed parameter model.The measurement function of algorithm is derived according to boundary conditions of different fault types and the pure resistance properties of the transition resistance.For fault occurring near teed point with high transition resistance leading to ranging pseudo root,the algorithm uses the back thrust line fault location results to determine the difference value and the measured value of the pseudo root side ends of current calculation.The fault location algorithm can accurately determine the fault section,and on this basis,using the double-terminal method to complete the fault location.Theoretical analysis and simulation results show that the algorithm does not contain fault location dead zone and is not affected by transition resistance,distributed capacitance,system impedance and other factors.Considering the multi-terminal transmission line with the algorithm given in power estimation.The limit condition is not easy to complete fault location,based on other multi-terminal transmission line fault location algorithm,the paper generalizes a fault location algorithm based on node voltage comparison.The algorithm uses distributed parameter model and calculates the node voltage from both sides of the main line and compares the node voltage with node voltage calculated from teed system to determine the fault section.The method can also use the voltage criterion to determine the fault section further when the fault occurred near teed point.PSCAD simulation results show that this method is accurate in fault section determination and high accuracy of fault location without dead zone.Finally,according to the harsh conditions of wind power system fault such as weak feedback,positive and negative sequence impedance inconsistency and line length asymmetry,this paper proposes the algorithm are given adaptive voltage comparison parameter and the current direction of fault section criteria for improvement in the environment of wind power.DIgSILENT simulation results show that the positive and negative sequence impedance inconsistency does not affect the algorithm and the effectiveness of the improved measures introduced.