Enhanced fault location method for shunt capacitor banks

Abstract

High Voltage Shunt Capacitor Banks (SCBs) are the most economical and critical components in the power system, providing reactive power and voltage support. Over temperature, over voltages, manufacturing defects can cause internal failures of capacitor elements. With todays sensitive protection available in numerical relays capacitor elements failure will be detected and capacitor bank will be taken out of service. But determining the phase and section in which capacitor elements have failed is important for utilities to expedite their repair process and can decrease downtime of this critical component. To address these issues of locating capacitor elements failures, this paper proposes an enhanced scheme for fault location detection in both grounded and ungrounded Y-Y SCBs; both for fuseless and internally fused units. Simulations of the proposed fault location method are carried out using PSCAD and MATLAB. The results validate the proposed method performance under pre-existing inherent unbalances, system voltage unbalance, and faults in the grid. The application and significance of the proposed method properties are demonstrated using illustrative simulation scenarios. This method can be integrated into a common unbalance protection of the multi-functional numerical capacitor bank relays and puts forth solutions to enhance fault location of SCBs. The method is capable of detecting consecutive capacitor elements failures, and also can mitigate gradual capacitance change due to temperature effects or natural aging. The presented fault location method is further enhanced to detect the number of failed elements.