Optimal Control Method of TVR with the Function of Suppressing Three-phase Voltage Imbalance and Improvement of the Suppressing Ability by the Individually-controlled Three-phase Type

In recent years, various issues related to distribution voltage quality have occurred due to the spread of distributed power supplies. The expansion of three-phase unbalanced voltage, caused by an increase of single-phase PV(Photovoltaic power generation), is one of these problems. It causes many problems, among which the decline of the SVR(Step voltage regulator)'s voltage regulation performance is a major issue. To solve these problems, we have invented and developed a new type of TVR (Thyristor-type SVR). Namely, an individually-controlled three-phase type of TVR with the function of suppressing three-phase voltage imbalance. In this report, we will describe our newly developed optimal control law of TVR with the function of suppressing three-phase voltage imbalance, and the unbalance suppression capability of the individually-controlled three-phase type of TVR while using this law, when compared to other types of TVR.