Transients outrush current analysis and mitigation: A Case study of Afghanistan North East power system

Abstract

This study evaluates the inconveniences raised by the installation of Shunt Capacitor Banks (SCB) along the North East Power System (NEPS) in Afghanistan. Besides the numerous advantages, a capacitor bank usually has some drawbacks in terms of transient currents which affect the quality of power supply and exceed the withstand capability of associated equipment. In this study, transient outrush current injects by installed SCB into the nearby faulted point at Pule Khumri and Chimtala substations is investigated. Outrush transient is produced by SCB when the breaker is operating to disconnect the faulted circuit. By applying different methods can mitigate outrush transient and protect the system which Current Limiting Inductance (CLI) is preferred in this study. Integrating CLI in series with SCB is the most relevant method which can limit the amplitude, frequency, and the rate of rise of the outrush transient. The use of inductance could otherwise create some excessive voltage which might exceeds the withstand capability of circuit breakers. Hence sensitivity analysis based on Transient Recovery Voltage (TRV) to confirm the robustness of the proposed approach is carried out. The evaluation is accomplished based on the result derived from the Electromagnetic Transients Program (EMTP), ATP package.

Keywords

• capacitor bank
• transient outrush current
• transient inrush current
• rate of rise of current
• power quality