Distribution system voltage regulation under fault conditions using static series regulators

Power quality and availability are becoming important issues for critical and sensitive loads. Many of the disturbances are caused by faults on the utility distribution system in one or more phases, resulting in voltage dips and sags. This paper presents a viable alternative to UPS solutions to three phase load support in the form of practical series compensator structures. The compensators consist of transformer coupled voltage source inverters fed from a single diode rectifier connected to the faulted AC supply. The balancing and regulating algorithms are developed and applied to partial and total single phase to three phase type of faults. The compensation capability of the proposed schemes are derived. Practical issues, such as design, converter rating and the relative merits of each topology are considered. The paper also provides experimental results for a 2 kVA prototype power conditioner