Fixed Point Implementation of Grid Tied Inverter in Digital Signal Processing Controller

Abstract

Power inverters are one of the devices of great importance used in power grids to convert DC to AC, especially for grids with attached solar panels or wind turbines. The world is getting warmer due to coal- and oil-based power generation. So human existence is threatened due to the increased amount of carbon-dioxide in the air. As a result, integration of renewable energy sources (RESs) with the grid became mandatory. So, the demand of grid-connected inverters is increasing as more RESs are connecting with the grid; this necessitates developing a low-cost grid connected inverter system. This paper presents a comprehensive study and hardware implementation of a grid tied inverter. In this research, we have demonstrated a cost-efficient grid tied inverter design using low cost DSP controller applying fixed point arithmetic. The fixed-point arithmetic and Digital Signal Processing (DSP) implementation results in superior performance over conventional methods of calculation. This paper also proposes a hardware model of such a bi-directional grid tied inverter. A current controlled Voltage Source Inverter(VSI) is used in the paper and a PI controller is suggested for current error compensation. To generate gating pulse for appropriate voltage, Space Vector Pulse Width Modulation (SVPWM) technique is employed. Synchronous Reference Frame Phase Locked Loop (SRF-PLL) is chosen for performing grid synchronization. The feasibility of the hardware model is verified by performing simulations on Simulink.