A Simulation Method Research On The Power Frequency Electric Field In The Ultra High Voltage Substation

In recent years with the rapid development of power industry and the continuous expansion of towns and cities, electric power system is moving in the direction of large electric capacity, great electric current, expansive power line system, high voltage, and long distance electricity transmission. Currently the power transmission and transformation systems of 500kV and above are being gradually popularized, with the presence of substations at the periphery of cities and towns, which had previously been located in outskirts. Ultra high voltage substations feature large arrays of equipments, extremely high voltage, and complicated line arrangement, with very intense and intricate electromagnetic fields inside the substations and in their neighboring areas Power frequency electric field and power frequency magnetic field are important components of electromagnetic fields in substations. The electrostatic induction caused by power frequency electric field will exert effects on electric appliances and ecology, and especially long-term or short-term physiological effects on human. Power frequency electromagnetic field and the resultant electrostatic induction have aroused public concern Hence it is of great significance to conduct the simulation research on the power frequency electric field in ultra high voltage substation.In accordance with the characteristics of the subject of research, this paper conducted simulation research on the target area by adopting the charge simulation method, and the numeric calculation method that combines charge simulation and method of moment. Firstly, on the basis of equivalency theory, an introduction was made of the fundamental idea of charge simulation method and its procedures of implementation. Then with the employment of weighting surplus method, an account was given of the structure of the method of moment and the steps of its application to the issue of electrostatic field, as well as the methods and application of combining charge simulation method and moment method. On this basis, a research was made of the field distributions of common charge simulation, As a result of the extreme multitude and wide distribution of linear electrodes in the ultra high voltage substation, necessary hypotheses and disposals were conducted for them to establish physical and mathematical models for the electric field calculations of three-phase long bus, three-phase short line and three-phase parabolic connecting lines. Through concrete examples of calculation, appropriate numeric calculation approaches were adopted to conduct calculation of their electric field distribution. And Matlab was utilized to compile simulation program for the visible analysis of their field distribution. Also a discussion was also made over the relevant factors affecting their field distribution. On this basis, in view of the concrete conditions of the ultra high voltage substations and the actual connection of electrical equipments, the local area constituted by the bus, the disconnecting switches on both sides of the bus, and circuit breaker was chosen as the subject of research. Physical and mathematical models of electric field calculation were established to conduct simulation calculations, with concrete examples, of the fields and synthesized fields in the three directions within the area at a plane 1.5 meters above the ground level. Meanwhile Matlab was used to compile simulation program for the visible analysis of their field distribution. Comparisons against the calculated examples were also made of the fields caused by the changes in the locations of the installed equipments, in which process were discovered the field distribution characteristics within the area and the factors affecting the fields.