A unified voltage quality conditioner without reference calculation

Voltage quality is one of the most important factors of the power quality in distribution systems and is sensitive to many customers. Voltage quality problems include: Amplitude errors (regulation), harmonics, phase unbalance, sag or swell, flick, impulse, and interrupt/outage etc. This paper adopts the one cycle control (OCC) method in a series connection topology, which here acts as a unified voltage quality conditioner (UVQC) to deal with most of the problems identified above. The new OCC-UVQC has many advantages including no reference calculation resulting in a great simplicity, fast transient response, high precision, constant switching frequency, and excellent reliability. The principle of the proposed UVQC is provided in detail. The performances of voltage quality improvement are verified by simulation and experimental results.