Hydraulic Buffer Design of 800kV Fast Circuit Breaker

Large oil-filled equipment such as converter transformer is an important equipment in UHV transmission system. However, a sudden increase in pressure due to a long arc fault can cause an explosion of the oil-filled device, which seriously threatens the safe and stable operation of the power system. This requires the circuit breaker to quickly remove the fault and shorten the energy injection time. The project team has already developed an 800kV fast circuit breaker, which shortened the breaking time from the conventional 50ms to 25ms, Due to the increase of speed, there will be problems such as impact and vibration, which will easily cause impact damage to key components. This requires reasonable design of hydraulic buffer to improve mechanical reliability. In this paper, the mathematical model of hydraulic operation and hydraulic buffer is established based on the theory of hydraulic fluid mechanics. Aiming at the stepped buffer structure, the buffer characteristics of the opening process under different buffer parameters are analyzed, and the optimal design parameters are obtained. The final velocity decreased from 0.97 m/s to 0.78 m/s, the peak buffer pressure decreased from 119.8 MPa to 39.3 MPa, and the range of peak buffer pressure decreased from 89.8 MPa to 21 MPa. Based on the simulation analysis results, the buffer column of the actual prototype is improved, and the accuracy of the simulation is verified by the measured displacement curve. This paper provides a reference for the buffer design of the hydraulic operating mechanism of the fast circuit breaker.