Abstract
Due to heavily load fluctuations or unexpected faults in power systems, voltage sags and unbalanced problems are one of the important issues for power distribution systems, especially for sensitive loads such as high-tech industrial parks. In recent years, due to rapid development of high-power electronics technology, it is possible to provide such voltage supports during the very short transient period by installing Static Synchronous Compensators (STATCOMs). When either the balanced or unbalanced voltage sag occurs in the point of common connection (PCC) of the system, or loads switching in the load bus, this STATCOM will provide adequate voltage supports. This thesis will report hardware implementations of a small laboratory-scale STATCOM. The rating of this three-phase STATCOM is 110 V, and 1 KVA. By applying the Synchronous Reference Frame (SRF) theory, the mathematical model of the STATCOM under the positive sequence and the negative sequence are described. The inner/outer two-loop decoupled control strategy is explored. The inner loop control is for the current command tracking while the outer loop control is for the bus AC voltage and the DC-link voltage control. The proposed control configuration has been validated under PSCAD simulations and hardware laboratory implementations. Experimental works on various operating conditions have been conducted to verify the effectiveness of the proposed control strategy. Keywords: Voltage Sags, Unbalanced Systems, Static Synchronous Compensator (STATCOM), Synchronous Reference Frame (SRF), Decoupled Control, Laboratory Platform Implementations.