Researches Of Voltage And Electric Field Distribution Along Insulator Strings Of 110kV Transmission Line

The stray capacitance between the insulator's hardware fittings and the towers and conductors, leading to serious distortion of voltage distribution and strong partial electric field.It's easy to corona, degradation, flashover or breakdown. Therefore voltage and electric filed distribution of the transmission line insulator strings is very important to the design and operation and maintenance.110kV transmission line routes are located in different geographical environments, different weather conditions and different grades pollution .So different type of towers and insulator strings (including insulators models, unit number, linear / strain / jumper string, single /double /V-strings), and different conductors with different payment arrangement, the situation is more complex. Most of the existing references of the numerical calculation of the insulators in abroad and at home are mainly related to single insulator string, and there are few references related to the strings with different towers and special installation forms of insulator strings, such as parallel multi-strings. This paper mainly studied the voltage and electric field of the single insulators with three different towers (tube single pole, portal double pole, cup type steel tower) and the parallel double- strings with portal double pole. Then compared and analyzed the results.In this paper, generalized the electrostatic field calculation method and then chosen finite element method according to the characteristics of the insulator string model. In accordance with the insulator structure and the actual working conditions. A 3-D model was developed. The influence of the wire and concrete structure of the tower was taken into account. Using sub-models to model the tower, conductor, insulator string regions. The insulator string voltage and electric field was calculated and summed up.The result shows that tower's different type has little effect to the voltage and electric field distribution of the insulators. The largest electric field appears on the head and porcelain pieces connection of the first piece of the insulators near the wire. The voltage and electric field of the double strings tended to be uniform with decreasing distance between two series. Compared with the single-string, double string reduced the voltage of the ends, but increased the voltage of the intermediate string.Compared with the calculated and standard results, and analyzed of the reasons for the error. The results can be used to study the insulator strings flashover mechanism of frequency voltage 110kV transmission line, and conform to the way of installation for the safe operation of the circuit, and provide some guidance for the structural optimization of insulator and the connection fittings.It can also used to design the voltage-sharing measures for improving the voltage distribution. Mastering insulator voltage distribution can provide a reference for On-line detection of zero value insulators. In addition, knowing and improving the electric field distribution is extremely important to knowing the corona and noise level of transmission line.