A Transformerless 2-Level Inverter Based Static Var Generator with Multiple Functions in Medium Voltage Application

This paper proposes a transformerless 2-level inverter based static var generator (SVG), which employs 20 series-connected IGBTs in each leg of the bridge for medium voltage blocking capability. The multifunctional SVG is used to compensate reactive power, negative sequence current, current harmonics and unbalanced utility voltages. Especially, a voltage controlled current source (VCCS) strategy is introduced and analyzed to mitigate grid voltage unbalance. Furthermore, the approaches to generating the reference signal for the SVG control circuit is presented according to different compensation objectives. Successful field installation and test results under 6kV voltage level showed satisfactory performance of the proposed SVG