Small Signal Modeling and Control of a Grid Tied Converter without a Syncronization Unit

In this paper, control of a grid-tied converter as a voltage controlled converter is investigated for distribution level grids. Small signal model of the converter is presented and a control structure is designed to deliver desired active and reactive power. This controller is using power flow equations to control the converter as a synchronous machine and without the need for a dedicated synchronization unit (PLL) during its normal operation. It is demonstrated that the controller ensures decoupled control and is immune to grid frequency fluctuations