Calculation Of The Extra High Voltage Transmission Line Parameters, Ground Wire Loss And Secondary Arc Current

In recent years, the rapid development of China's power grid, transmission line level also increased gradually, HV and EHV and UHV transmission lines usually use two wires. And most papers only discuss two wires are connected to the situation, but the current common practice in engineering is the ground lines of optical fiber composite overhead ground wire(OPGW) continuity, and another common ground wire(CGW) section by section grounding. For two wire grounding mode of transmission lines, electromagnetic transient simulation software ATP-EMTP program cannot direct calculation the line parameters, ground loss, potential for current, are calculated and the calculated results have a certain error. So this paper will construct the new simulation model, a new calculation method research.Firstly, ATP-EMTP is used to simulate a 750 kV transmission line, and the impedance matrix is established. After elimination of ground, by Karrenbauer transformation, transformed impedance matrix is symmetric matrix were calculated in line with OPGW by base grounding, CGW piecewise grounding; OPGW and CGW were by the base ground; OPGW and CGW are piecewise grounding impedance and capacitance of positive sequence and zero sequence parameters.Secondly, in OPGW used by the base grounding mode, CGW piecewise grounding, calculation of OPGW current and CGW resistance; OPGW and the diameter of the DC resistivity change and analysis of influence of outer diameter and the DC resistivity of ground power loss; power loss and the conductor transposition or OPGW and CGW were by the base ground case relative contrast and analysis transposed conductor and ground wire grounding mode of ground wire loss effect.Finally, according to the calculation method of the existing research, it is determined that the reactance of each shunt reactor and the neutral point of shunt reactor are the size of small reactance when the compensation amount is 90%. Considering the factors of different fault location, grounding phase, line load and grounding resistance, the steady state potential current of single phase to ground fault in 750 kV transmission line is calculated and analyzed.