Research Of Mechanical Properties And Synchronous Control For 126kV High Voltage Vacuum Circuit Breaker

Vacuum circuit breaker(VCB) is important power equipment in power transmission and distribution system and is widely used due to its unparalleled advantages. Most power grids in China directly use 126 kV voltage class in urban areas, therefore, developing 126 k V VCB is imminent and its successful development will be of great application value.VCB is a mechanical device that has electrical performance, which in turn depends on its mechanical properties. In this paper, based on the analysis of its electrical performance parameters, the mechanical properties of VCB and the influence factors are analyzed. Considering the application environment and technical parameters of 126 kV VCB and exploiting the theory of breaks connected in series, a VCB composed of two 72.5kV vacuum interrupters connected in series is considered more reasonable. As the key components of VCB, vacuum interrupters are designed base on its multi-gap theory. By using virtual prototyping technology, the diameter of conducting rod is determined, and the distance between contacts that the vacuum breakdown often occurred in is received through the simulation of electric arc struck during vacuum breakdown, moreover, the voltage-sharing shielding cover is designed and reasonably configured such that the internal electric field inside is evenly distributed. According to the discussion on voltage sharing features of VCB with double breaks, a new ▽ configuration structure that two breaks connected in series is presented, and the hidden danger of insulation caused by the parallel voltage sharing capacitor is effectively avoided.The operating system of high-voltage VCB being in series with ▽ new configuration is analyzed and designed. Monostable permanent magnetic structure is used for the actuator. Based on the discussion of driving mechanism, tension rods are used to transmit power. To increase the breaking speed of VCB to the benefit of breaking, the driving mechanism is equipped with a breaking spring. Also, the dead point principle of the mechanical structure is utilized to reduce closing retentivity of permanent magnet mechanism. Based on kinematic and dynamic analysis of VCB, optimization of operating system is performed using genetic algorithm with the purpose of achieving optimal mechanical properties.Simulation and optimization of the VCB operating system is performed by combining virtual prototyping technology. After having established and simplified the 3D model, the boundary conditions are set up depending on actual running state. The breaking and closing processes are simulated and analyzed, and the model is gradually optimized so that the breaking and closing speeds meet the design requirements. The design method has shortened the development cycle and reduced the cost, at the same time, provides reference for designing other types of circuit breakers.Synchronous control of VCB is the basis of its performance getting implemented, and synchronous controller of VCB is designed in this paper. To efficiently remove the noise, FIR filter is designed and then to extract the zero crossing point of signal after being filtered by linear interpolation method. BP neural network model for predicting the time of breaking and closing of VCB is trained by L-M algorithm. The frequency and phase of the signal are determined by fast Fourier transform. For hardware circuit, of which the CPU module, power module, control circuit, analog signal acquisition and self-checking circuit, ambient temperature measurement circuit, communication circuit and anti-interference are designed.According to Standard No. GB 1984-2014, the experimental platform and the Weil synthesis loop are set up, and the 126 kV VCB is tested for mechanical properties, current carrying property, insulation property and breaking capability etc. All tests show that the 126 kV VCB satisfies the national type test standard and is qualified to be connected to the grid and for industrialized manufacturing. At the same time, the feasibility of developing VCB with multi-fractures to the high-voltage level is fully demonstrated.Type test is ongoing for this 126 kV VCB at high voltage apparatus quality test center of mechanical industry now. The device will be connected to the grid at Shigezhuang Substation at the end of 2016.