Design and implementation of a 1kw single phase grid tie inverter

Renewable energy sources and their power processing equipments are gaining increasing importance in the market. Excess of energy harvested from a renewable source is either stored for future use or sold to other users that are in need of electrical energy at the time of harvesting. Since storage of excess energy is an ine fficient and costly process, a better way of dealing with excess energy is to transfer the energy to the interconnected power grid by means of appropriate power processing. In this thesis work, design and implementation of a high e - fficiency power processing equipment known as Grid Tie Inverter (GTI) to achieve energy transfer to the grid is studied. The target of this study is to convert low voltage direct current (DC) electrical energy harvested from the photo voltaic (PV) panels to high voltage alternating current (AC). The magnitude and phase of the processed alternating current is then controlled in a way such that the power ows towards the grid with a low DC and low reactive component. To achieve this goal, the voltage of the PV panels is stepped up to an appropriate DC link voltage by using a boost type converter known as the Z-Source. The required DC analysis and transfer functions iv of the Z-Source converter are obtained by the circuit averaging technique and a proportional-integral (PI) regulator is designed and implemented to stabilize the DC link voltage. The stabilized DC link voltage is then converted to alternating current using a full bridge inverter. The required grid voltage and phase information is obtained by digital implementation of a single phase time-delay based synchronous reference frame phase locked loop circuit (TDB-SRF PLL). The control of the current owing into the grid is carried out by using the D-Q synchronous reference frame approach. Hereby, the direct (D) and quadrature (Q) components of the grid current are calculated using Park's transformation. The magnitudes of the D and Q components are stabilized by separate digital PI controllers. The outputs of the PI controllers are then converted back to the rotating reference frame using the inverse Park's transformation. The output of the transformation is used as a control signal to drive the full bridge inverter. The scope of the thesis comprises both the modeling and simulation of the GTI components and the design and implementation of a prototype GTI. A thorough experimental evaluation con rms the practicability of the proposed design.