Experimental study of effect of disconnector speed on very fast transient over voltages in a 420kV gas insulated substation

الملخص EN

Very fast transient overvoltages (VFTO) are generated during the switching operation of Disconnector Switch (DS) in gas-insulated substations(GIS).

The severity of VFTOs increases with voltage level.

Such overvoltages can cause malfunctioning of protective circuits.

The Disconnector speed is a very important parameter that influences the VFTO, but very little study has been done on this.

In this paper, the effect of DS speed on VFTO Characteristics on the magnitude of trapped charge has been considered.

The 420kV GIS system is modeled using EMTP-RV.

The various components are represented with their equivalent models.

The Disconnector arc is modeled using the Mayer arc model.

The DS arc is modeled as a nonlinear equation and the dynamic nature of resistance is modeled in EMTP-RV.

The four important locations were considered to estimate the VFTO magnitudes at various DS speeds.

The impact of DS speed on VFTO has been studied.

Experimental validation is done on Gwaka 420kV GIS, Vizag, INDIA.

The results are validated with the experimental measurements.

The amplitudes at high DS speeds are relatively low when compared to the low speeds of operation.

It is also observed that the operating speed is effecting the amplitudes and rise times as well The simulation test results are closely matched with the experimental results.

The results show the DS operating speeds are strongly affecting the VFTO characteristics and trapped charge magnitudes and the DS speeds must be operated in a particular range.