The design technology for HV SF6 gas circuit breakers is very demanding.A numerical method for prediction of the thermal interruption capability of SF6 gas circuit breakers is established based on the two-dimensional ...The design technology for HV SF6 gas circuit breakers is very demanding.A numerical method for prediction of the thermal interruption capability of SF6 gas circuit breakers is established based on the two-dimensional magneto-hydrodynamic(MHD) model and a commercial CFD(computational fluid dynamics) software,FLUENT.Nozzle ablation effect is considered by introducing an independent mass conservation equation for the ablated material to the overall conservation equations of mass,momentum,and energy.The ohmic heating and the radiation of the electric arc are considered in the model by adding relevant source terms.To predict the thermal interruption capability,the arc conductance 200 ns before current zero is used as an indicator.The CFD model is applied for the high current arcing phase,and Mayr arc model is used near the current zero period.The arc conductance at 200 ns before current zero(G200) for various arcing periods are computed by the present method.It shows that there exist a limit of the G200.For those whose arcing periods are within the arcing window,the related G200 are below the limit,therefore result a successful current interruption,and vice versa.The validation of the developed computer simulation tool is therefore verified.The numerical prediction by the simulation tool is verified by the direct interrupting test of 550 kV gas circuit breaker(GCB).The developed computer simulation tool was applied in the design of a 550 kV GCB.Significant benefits have been achieved in terms of both the cost saving and shorten of the development cycle.展开更多
基于建立的可拆式高压气体断路器,研究了SF_6-CF_4气体的电弧开断特性。采用数字延时脉冲发生器控制断路器操作机构和晶闸管等的动作时序,利用屏蔽网包裹信号线以降低电磁干扰,借助毕托管和管内阻尼颗粒实现压力传感器的绝缘和隔热并抑...基于建立的可拆式高压气体断路器,研究了SF_6-CF_4气体的电弧开断特性。采用数字延时脉冲发生器控制断路器操作机构和晶闸管等的动作时序,利用屏蔽网包裹信号线以降低电磁干扰,借助毕托管和管内阻尼颗粒实现压力传感器的绝缘和隔热并抑制管内压力波的振荡。利用硅压阻式传感器和零区测量设备分别测量了电弧开断过程中喷口喉部气压及零区电压电流的变化。分析了短路电流和气体配比等对灭弧室中喷口喉部气压变化和电弧零区行为等的影响。将Mayr电弧模型应用于弧后行为的预测,通过改变恢复电压上升率(rate of rise of recovery voltage,RRRV)和零前电流斜率(di/dt)来分析SF_6-CF_4电弧的零区特性。结果表明,在SF_6中添加CF_4后,测量点气压增量及临界恢复电压上升率趋于下降。计算得到SF_6和50%SF_6-50%CF_4的临界弧后电流分别为0.74A和0.96A。50%SF_6-50%CF_4中临界恢复电压上升率为SF_6的77%,临界恢复电压上升率和测量点气压增量之间呈现出一定的相关性。展开更多
文摘The design technology for HV SF6 gas circuit breakers is very demanding.A numerical method for prediction of the thermal interruption capability of SF6 gas circuit breakers is established based on the two-dimensional magneto-hydrodynamic(MHD) model and a commercial CFD(computational fluid dynamics) software,FLUENT.Nozzle ablation effect is considered by introducing an independent mass conservation equation for the ablated material to the overall conservation equations of mass,momentum,and energy.The ohmic heating and the radiation of the electric arc are considered in the model by adding relevant source terms.To predict the thermal interruption capability,the arc conductance 200 ns before current zero is used as an indicator.The CFD model is applied for the high current arcing phase,and Mayr arc model is used near the current zero period.The arc conductance at 200 ns before current zero(G200) for various arcing periods are computed by the present method.It shows that there exist a limit of the G200.For those whose arcing periods are within the arcing window,the related G200 are below the limit,therefore result a successful current interruption,and vice versa.The validation of the developed computer simulation tool is therefore verified.The numerical prediction by the simulation tool is verified by the direct interrupting test of 550 kV gas circuit breaker(GCB).The developed computer simulation tool was applied in the design of a 550 kV GCB.Significant benefits have been achieved in terms of both the cost saving and shorten of the development cycle.
文摘基于建立的可拆式高压气体断路器,研究了SF_6-CF_4气体的电弧开断特性。采用数字延时脉冲发生器控制断路器操作机构和晶闸管等的动作时序,利用屏蔽网包裹信号线以降低电磁干扰,借助毕托管和管内阻尼颗粒实现压力传感器的绝缘和隔热并抑制管内压力波的振荡。利用硅压阻式传感器和零区测量设备分别测量了电弧开断过程中喷口喉部气压及零区电压电流的变化。分析了短路电流和气体配比等对灭弧室中喷口喉部气压变化和电弧零区行为等的影响。将Mayr电弧模型应用于弧后行为的预测,通过改变恢复电压上升率(rate of rise of recovery voltage,RRRV)和零前电流斜率(di/dt)来分析SF_6-CF_4电弧的零区特性。结果表明,在SF_6中添加CF_4后,测量点气压增量及临界恢复电压上升率趋于下降。计算得到SF_6和50%SF_6-50%CF_4的临界弧后电流分别为0.74A和0.96A。50%SF_6-50%CF_4中临界恢复电压上升率为SF_6的77%,临界恢复电压上升率和测量点气压增量之间呈现出一定的相关性。
