A Hybrid Voltage Regulator with Arcless Tap Change and Stepless Voltage Regulation Functions

Abstract

Step voltage regulator (SVR) has been utilized in the power distribution systems for decades. The induced arc from the conventional SVR tap change and the voltage instability from the renewable energy penetration impose constraints on the conventional SVRs’ lifetime. Meanwhile the voltage regulation accuracy cannot be guaranteed since the SVR regulates the voltage step by step. The power electronics transformer solution was proposed but requires the power converter capacity proportional to the voltage regulation range, which significantly increases the system cost. This paper proposed a hybrid voltage regulator that achieves arcless tap change and stepless voltage regulation by using a back-to-back power converter. Load voltage regulation continuity is guaranteed while the tap changer mechanism remains in the system, which helps to promote the upgrade to the existing power distribution systems. The required converter capacity in the proposed topology is 0.31% of the distribution transformer rating, which also reduces the system cost compared with the full power electronics solutions. The proposed hybrid voltage regulator was simulated and experimentally validated. The experimental results demonstrate arcless tap change operation, stepless voltage regulation, and load voltage continuity during the tap change.