Research On Fault Location Algorithm Of High Voltage Transmission Line Based On Distributed Parameter Model

High voltage transmission lines are the key part of electricity transmission in the power system,their safe and reliable operation is the basic condition to ensure power supply and an important guarantee for the stable development of national economy.Transmission line fault location is an important means to improve the reliability of power supply,and promote the safe and stable operation of power grid technically.Taking the economy,transmission line corridors,occupied area and electric power demand into account,the structure of power system is becoming increasingly complex with the appearance of double-circuit transmission lines on same tower,non-full-length double-circuit transmission lines,teed lines,overhead-cable mixed lines.Compared with three-phase transmission lines,it is more difficult to locate the fault of complex structure lines,so it is necessary to conduct further research.Based on the distributed parameter model,this paper studies the fault location algorithms of high voltage transmission lines with various structures.First of all,a new fault location algorithm for double-circuit transmission lines on same tower with shunt reactor is proposed.The fundamental frequency components of both ends of double-circuit transmission lines are decoupled by the six-sequence method.An index fault locating function is constructed on the basis of the homotopic positive sequence network,and the linear phase characteristic of the fault locating function is utilized to locate the fault.Compared with the existing algorithms,the principle of this method is simple without pseudo-roots.It does not need to search the fault point within the full range of line,so it has a small calculation.Secondly,a asynchronous fault location algorithm for non-full-length doublecircuit transmission lines is proposed.The fault branch is determined according to the connection point voltage amplitude calculated with positive sequence fault component of two ends,and then the fault position is solved on the fault branch precisely using asynchronous data.The algorithm does not need to synchronize the data at each end.No iterative search and pseudo-root recognition is required to locate the fault position.It has a good applicability of various fault types for both single and double transmission line segments.Thirdly,a new fault location algorithm for double circuit teed lines based on positive sequence current difference is proposed.The fault branch is determined according to the phase difference of the fault location function at the head and end of three branches,and then the fault distance is solved on the fault branch precisely by using the expression for fault distance calculated by double circuit positive sequence fault location equation.There is no dead zone when the fault branch is determined.No iterative search and pseudo-root recognition is required to locate the fault position.The algorithm is not affected by the transition impedance property,it overcomes the defects of the existing T-line fault location algorithms.Finally,a new fault location algorithm for overhead-cable mixed lines based on fault section fast identification is proposed.The fault section is determined according to the phase characteristics of fault section recognition function at the line connections,and then the fault distance is solved on the fault section precisely by using the expression for fault distance calculated by mixed lines positive sequence fault location equation.The algorithm does not need to judge the fault type.There is no dead zone when the fault section is determined near the line connections.Also,no iterative search and pseudo-root recognition is required to locate the fault position.It is easy to be implemented.The fault location algorithms proposed in this paper have high engineering practical value,a large number of simulation experiments verify their effectiveness.