DSTAR Participation in DistribuTECH 2015
Utilities have installed many electronic devices (IEDs) to enable safe, reliable, and efficient operation of the distribution system. These IEDs include controllers for overhead feeder capacitor banks. Some utilities have reported controller failures due to power surges and overvoltage events.
This presentation is based on Project 14-4: Surge Protection of Electronic Capacitor Controllers in Distribution Systems. It summarizes an investigation by which controller installations at several utilities were simulated in the Alternative Transient Program (ATP) to quantify the surge voltage and currents on the distribution circuit as well as on the controller circuits. The controller is powered via the control power transformer (CPT) which reduces the feeder voltage (typically 15, 25, or 35 kV) to 120 V. The impact of surge arresters at the CPT and/or the controller were investigated relative to surge voltages at the controller.
In addition, the impact of transformer and controller ground connections were also investigated. To improve quality of the CPT model, several frequency scans were performed on a 0.5 kVA CPT from which a terminal model was synthesized for the ATP model. From the parametric analysis, several recommendations for CPT and controller grounding as well as surge arrester placement were developed.