Mitigation of Capacitor Bank Energization Harmonic Transients
In the present study, an overview of the capacitor bank energizing transients is presented and the means of harmonic mitigation technique are investigated. Capacitor bank connection is essential due to reactive compensation reasons. Transients produced upon of capacitor bank energizing, reach in harmonics, may be harmful for the capacitor and become an increasing concern for both electric utilities and customers since its switching usually occurs quite frequently. We know that power factor correction capacitors are sensitive to harmonics and one factor of the failures of power capacitors indicates the prime odd harmonics like 5th, 7th, 11th, 13th harmonics. A time domain simulation using PSCAD/EMTDC was performed to predict the harmonic spectrum of the distorted voltage waveform in a real 11 kV Romanian distribution subsystem
Shunt Capacitor Overvoltages and a Reduction Technique
Switching of shunt capacitor banks results in transients at the switched capacitor bank location and at other locations in the power system. Pre-insertion inductors are often applied to reduce overvoltages and inrush currents associated with switching shunt capacitor banks. This presentation gives an overview of the most common capacitorswitching transients and discusses simple techniques for determining the effectiveness of preinsertion inductors in reducing these transients. Results of field measurements involving the application of lowand high-resistance pre-insertion inductors are also presented.
Evaluating capacitor-switching devices for preventing nuisance tripping of adjustable-speed drives due to voltage magnification
Nuisance overvoltage tripping of pulse-width modulated adjustable-speed drives, due to switching of shunt capacitor banks at a utility's substation and the subsequent voltage magnification which can occur at an industrial customer's utilization-voltage bus, is discussed. Adjustable-speed drive design considerations affecting transient overvoltage ride-through capability are identified and discussed. A comparative evaluation of three switching devices equipped with transient overvoltage control, namely, circuit breakers with pre-insertion resistors, circuit switchers with highly damped pre-insertion inductors, and controlled closing devices, is presented.