Design of a Single-Phase Two-Winding Transformer for Prototyping a Voltage Regulator

The wide use of dispersed generation in distribution networks intensifies the need for voltage regulation, even in low-voltage (LV) networks. These grids present simpler structures than the medium voltage (MV) ones, but with a consistently larger number of buses and feeders; for them, voltage control devices must ensure rapid and reliable operations, as well as affordable and easy implementation. Maintaining proper voltage amplitude is a major concern for active users, characterized by both generation and load; their injection/absorption can lead to extended voltage variations that exceed the typical operating range of the feeder, resulting in distributed generation failures and lower power quality for the loads. A ‘proof of concept’ of a simple, compact, and cost-effective device for LV regulation was recently presented. The device mainly comprises a single-phase two-winding transformer that alters its configuration by static switches to maintain the correct voltage of the user. The emphasis of this study is on a new version of the transformer that aims to address some limitations previously identified, to extend the operation of the device. A complete redesign of the transformer is proposed, as well as the presentation of its design features and operating characteristics. The paper details several laboratory tests performed on the device in various operating conditions, showing the benefits introduced by the new transformer.