Research On The Key Technology Of 24kV Permanent Magnetic Actuator Vacuum Circuit Breaker

The 24kV Outdoor Vacuum Circuit Breakers are the critical equipments which are widely used in the 20kV voltage level distribution system. With the construction and transformation of the 20kV distribution network deepening and extending in China's electric power system, the theoretical study of the 24kV Outdoor Vacuum Circuit Breaker is speeding up. To improve the design and manufacturing standards, and to research and develop the domestic key equipment with the international advanced level of the 20kV distribution network, as well as to change the current import-dependent status of the 24kV Vacuum Circuit Breakers, have become one of the key issues for the development of the distribution network.This thesis aims at the study of the key technology of the small, low-cost, high-performance permanent magnet 24kV Outdoor Vacuum Circuit Breaker. With the background of the actual engineering project of the construction and transformation of China's 20kV voltage distribution network, in the light of the basic requirements of the vacuum interrupter, which include that the operation of power is small, the overall structure and the size of installation is small, the weight is light, the dielectric strength is high, the cost of manufacturing and maintenance is low, this study emphasizes on the structural optimization of the vacuum interrupter and the insulation and the dynamic characteristics of the permanent magnet actuator, and establishes the theoretical design and the simulation models of the 24kV Vacuum Circuit Breaker with permanent magnetic actuator on the outdoor columns. Drawing support from the cooperation with Nanjing Electric Power Automation Equipment Co. Ltd. Yin Tailai, the ZW32A-24/D1250-25 series of small vacuum circuit breaker with permanent magnetic actuator on the outdoor columns has been researched and developed.Main contents of this paper are:(1) According to the demands of the actual engineering project technology of the small vacuum circuit breaker on the outdoor columns, aiming at minimizing the volume of the vacuum interrupter and the optimization of the electric field distribution, this study establishes the simulation model of the 24kV vacuum interrupter. Based on the three D modeling of the vacuum interrupter and the numerical analysis of electric field, this thesis studies the internal structure of the vacuum interrupter and the distribution of the electric field in static and dynamic states between contacts. By analyzing the influence of the open fracture on the electric field distribution, the structure and parameters of the interrupter and the contact has been adjusted to optimize the peak number of the electric field within the arc chamber to the position of departing from the site of the contact, whilereducing the maximum value of the electric field inside the interrupter, in order to achieve the goal that under the minimum increase of the size of the interrupter contrasted to the 12Kv vacuum interrupter, the insulation of the internal arc chamber can satisfy the requirements of the 24kV voltage level and there is sufficient margin.(2) According to the actual engineering projects demands of minimization of the overall size of installation and weight of the vacuum circuit breaker on the outdoor columns, the numerical simulation model of vacuum circuit breakers is established. This thesis also analyzes the characteristics of the electric field distribution of the fracture of the vacuum circuit breaker when under different external applied voltage. Through the numerical simulation of the static electric field, the best parameter configuration of the shield and the outer insulation sleeve is established. So that the level of pressure-resistance and dielectric strength can be no less than the national standard with the volume and size of the vacuum circuit breaker as small as possible.(3)According to the actual application environment of the distribution network that the operating power capacity of the circuit breakers on the outdoor columns is small, applying the power source of the 12kV outdoor circuit breakers to operate the 24kV outdoor circuit breakers, researching and establishing the dynamic mathematical simulation model of the permanent magnetic actuator to analyze the principle of design and the numerical calculations. In response to the closing problem of the monostable permanent magnet actuator with high-voltage and long journey, this study designs the new monostable permanent magnet actuator with changeable air gap self-locking style, and analyzes the magnetic circuit of the monostable permanent magnet system. Through the simulation analysis, the minimization of the operation power of the permanent magnet actuator has been realized under the premise of satisfying the parameters of the operating characteristics and reliability of the outdoor permanent magnetic actuator.(4) Based on the theoretical research and calculation result of the parameters design of the vacuum interrupter, the insulation structure and the permanent magnet actuator, this study researches and developed the ZW32A-24/D1250-25 Series 24kV Vacuum Circuit Breaker with Permanent Magnet Actuator on Outdoor Columns. The test of this product shows that it meets the national standards and the standards of power industry.