ELECTRONIC VOLTAGE REGULATOR APPARATUS AND METHOD

There is disclosed new topology for an Electronic Voltage Regulator (EVR) which can apply additive or subtractive (aka boost or buck) voltages to compensate for an increase or decrease in system voltages. This regulator employs a ladder of power capacitors which are in series and connected across the input voltage to apply different levels of voltages to a controlled or regulated transformer. Considering this, the proposed EVR can be utilized as a replacement for conventional electromechanical type on-load tap changers or (OLTCs) commonly used in power transformers, and meant to compensate voltage changes in a system. Electromechanical tap changers have some significant issues, such as defined time durations when switching to different taps, as determined by the spring-loaded mechanism's operation; a high malfunction rate due to mechanical switching when causing arcing, and thereby decreasing the operating lifetime of transformers. In this EVR instead of electromechanical taps, a combination of capacitors and TRIACs are used at each voltage level to eliminate arcing effects while increasing the speed of the tap changing process. Furthermore, the electronic regulator can improve the load power factor due to the presence of capacitors. Other advantages over conventional OLTC's is the elimination of a reactor, if used, and the elimination of a tap winding with its numerous tap leads and having correspondingly higher cost. This will reduce the overall size of the active part of the main transformers and improve efficiency by reducing operating losses. In addition, a new failure detection method is included that detects a failed TRIAC to enable the system to continue operating. The failure detection circuit is seamlessly incorporated within the main circuit and has a high-speed detection rate.