Research Of Fault Current Calculation In Transmission Line With OPGWs Based On Phase Component Method

In modern power system of China, most overhead transmission lines with a voltage level of or over 110kV are equipped with two overhead ground wires. Now the tendency is to replace the traditional ground wires with OPGW. This paper proposes an improved double-side elimination method based on the concept of phase component model to analyze the distribution of fault currents on OPGWs when the grounding fault occurs in overhead transmission system. The overhead transmission system is divided into different spans based on the gap between two towers. So the whole transmission line is made up of many spans. The transmission line and OPGW are regarded as an integral whole. Then the improved double-side elimination method is applied to solve these equations. By optimizing the block matrix, the essence of the improved double-side elimination method is released. And by combining all the parts at the boundary point, all currents on each span of OPGW can be obtained. Furthermore, compare with the method of calculating the grounding fault current first and then calculating fault current distributed on OPGWs based on mesh current, in order to confirm the results of the improved double-side elimination method is more suitable in engineering application.Based on the theory mentioned above, a calculation system is developed. By comparing the results of the calculation system and the results of some reference papers and the EMTP simulating, the correctness of the proposed theory and calculating results are confirmed. In addition, some effect factors of OPGW distribution are discussed. Finally, depending on the engineering project and the calculation system, a set of hardware system are developed and apples to a model line. Combine the software with the hardware, a complete system calculating fault current on OPGW and monitoring OPGWs are formed. The purpose of this paper is to apply the research content into engineering projects.