Design and Digital Implementation of a Medium-Voltage Transformerless Hybrid APF

摘要

This paper presents a transformerless hybrid active power filter (HAPF), a combination of passive power filter (PPF) and active power filter (APF), as a dynamic harmonic compensation device. Compared with the conventional parallel APF, HAPF has a smaller capacity, lower voltage rating of switching devices, smaller size, lower cost and better application in high voltage operation. At first, this article makes research on the operation principle and design, then, presents the detailed design method. A hybrid control strategy with both grid-side current feedback and load-side current feedforward is proposed. In addition, the stability of the feedback control is analyzed theoretically. An effective solution to improve the system stability is proposed. Finally, the compensation performance and the theoretical analysis are verified by the experimental results based on a 380V/10KVA downscaled laboratory system.