Kimiharu Kanemaru

New fault location system for power transmission lines using composite fiber-optic overhead ground wire (OPGW)

This paper describes a new method of locating the section where an electrical fault occurs on a power transmission line using Composite Fiber-Optic Overhead Ground Wires (OPGWs). This fault location (FL) method locates the fault section by measuring the current induced in the ground wire (GW), i.e., OPGW in this system. The OPGW currents are measured at many towers which divide the power line into sections. Data is transmitted to a central monitoring station as an optical signal through the optical fibers included within OPGW. Prior to the development of this new FL system, a simulation of power line faults using Electro-Magnetic Transients Program (EMTP) was conducted. As a result, the following two points were clarified; 1) Since OPGW current changes with line condition, it is quite difficult to define a fixed threshold level to locate fault sections accurately. 2) The distribution pattern of OPGW current along the power line has clear features around the fault point, so it is possible for electric power engineers to find the fault section by relative comparison. Therefore, the FL algorithm to be developed should have the capability of finding out the fault section with a human-like method of recognition. Fuzzy Theory, an attempt to include this kind of humanlike way of thinking into computers, was investigated and a new FL method applying this theory was developed. Fig. 1 shows the OPGW current distribution pattern of a typical grounding fault calculated by EMTP as an example.

Knowledge-based fault location system for electric power transmission lines with OPGW

For the reliable operation and efficient maintenance of electric power transmission lines, the authors developed a fault location system with composite fiber-optic overhead ground wire (OPGW). This system uses a knowledge-engineering approach together with fiber-optic technology. The system uses fuzzy theory in processing fault information of essential vagueness. Furthermore, the system uses domain-specific knowledge and the heuristics of power-transmission experts by applying an expert system. Actual fault-location results in complicated commercial lines have demonstrated the system to be quite practicable.<<ETX>>

A study on practical fault location system for power transmission lines using neural networks

For the efficient operation of power transmission facilities, the authors have developed a new fault location (FL) system and put it to practical use. This system uses neural networks to analyze the distribution pattern of the current induced in overhead ground wires along the poser line. Improved reliability results from the introduction of fuzzy operation of input data, a fault-type decision method and an index expressing the reliability of the fault location result. These FL systems are installed in eight commercial lines, and run normally, one of which experienced a fault due to lightning and successfully located the fault point.<<ETX>>