SVC model for voltage control of a microgrid

Low power renewable sources, connected to low voltage micro-grids, are becoming more and more common. Since there is a high degree of uncertainty on the availability of such sources, this causes problems of stability and makes difficult to guarantee the power quality (PQ) in all the points of the grid. Such kind of problems, are well known in medium voltage (MV) networks, where the proposed solutions to fix the stability and PQ problems are based on the control of reactive power flow in the grid. The equipment to perform such control function ranges from the simple capacitor banks driven by electro-mechanical contactors, through the Static Var Compensators (SVC) based on the combination of Thyristor Switched Capacitors (TSC) and Thyristor Controlled Reactors (TCR) or SVC combined with Active Power Filters (APF). This paper describes the design and implementation of a low power SVC prototype model, sizeable to higher power levels. It has been designed to compensate variations of the line voltage of a microgrid in a range of ±2%. The prototype can compensate 3kVAr capacitive and 1 kVAr inductive and is able to operate in a grid with a rated voltage of 400 V, phase to phase.