A High-Efficiency Low-Wearing Hybrid Voltage Regulator for Utility Applications

Abstract

Step voltage regulator (SVR) has been utilized in power distribution systems for decades as the voltage regulation device. Due to the increasing integration of distributed energy resources, the conventional SVR is severely challenged by the modern power distribution pattern with high renewable energy penetration. The induced arc from the conventional SVR tap change and more frequent tap changes due to voltage instability from the renewable energy impose constraints on the conventional SVRs lifetime. Meanwhile, the conventional SVR device cannot regulate the voltage accurately since the SVR regulates the voltage step-by-step. This article proposed a hybrid voltage regulator with high-efficiency and low contact wearing, which can achieve arcless tap change and stepless voltage regulation by using a fractionally rated back-to-back power converter. The accurate load voltage regulation is guaranteed, while the tap changer mechanism remains in the system, which helps to promote the upgrade to the existing power distribution systems. The power converter capacity in the proposed topology is only 0.31% of the distribution transformer rating to achieve a stepless voltage regulation range of ±10%, significantly reducing the system cost compared with the full power electronics solutions and projects high total system efficiency. The proposed hybrid voltage regulator was simulated and experimentally validated. The experimental results demonstrate arcless tap change operation and stepless voltage regulation. Collaborative operation between the conventional mechanical tap change and the power converter operation is also demonstrated to acquire large voltage regulation with fast-acting voltage control.