METHODS OF ENHANCING CAPACITY OF TRANSFORMER EQUIPMENT AND OF POWER FLOW CONTROL USING PHASE-SHIFTING TRANSFORMERS AND SERIES IMPEDANCES IN PARALLEL ARRANGEMENTS

摘要

To enhance the capacity of a transformer apparatus for a polyphase AC network, a constant current transformer branch (6) is connected in parallel with one or several conventional transformer branches (4) already in place in the transformer apparatus or added to form the transformer apparatus. The constant current transformer branch (6) includes a phase-shifting transformer (10) in series with reactive elements (12). For power flow control between two synchronous polyphase AC network busses (72, 74), two parallel branches (76, 84) are used, one including a phase-shifting transformer (78), the other including a reactive element (88). An additional phase-shifting transformer (86) is added in series with the reactive element (88) to enhance the power flow control flexibility.