Control Strategy for Transformer On-load Tap Changers in an Electrical Network with Embedded Generation using Fuzzy Logic

Fuzzy logic as a control strategy has been used in a variety of problem-solving applications across industries. This is a variable processing approach allowing for multiple possible truth values and degrees which are processed through the same subject variable. Active distribution networks are power systems where embedded generating units are present and are operating as integrated units to the process. Conventional voltage regulation in these active power distribution networks depend on transformer on-load tap changers (OLTCs) in conjunction with other voltage regulation schemes. As most prevalent OLTCs maintain the secondary output voltage of power transformers by adjusting the tap at the primary side to accommodate voltage variation to the primary winding of the transformer, the overall response of the tap changer control is influenced by embedded generation units in the network injecting a reverse power flow relative to the power flow from the utility to the primary side of the transformer. The conventional voltage reference of the OLTC looking at the secondary side of the transformer need to be re-evaluated to cover both variations in the primary side and secondary side of the power transformer.