Novel Direct Power Control Strategy for Single-Phase Photovoltaic Inverters

Abstract

In the design of inverter controllers, a phase-locked loop (PLL) is usually used to synchronize the inverter output with power grids. However, the adoption of PLL may increase the complexity of the controller. In addition, the accuracy of the PLL can be impacted if the power quality of the power grid is distorted, and the inaccurate PLL output can degrade the performance of the controller. To overcome these issues, a number of non-PLL control strategies have been studied for the single-phase PV inverter. In this work, a novel non-PLL direct power control strategy (DPC) for single-phase H-bridge SVPWM photovoltaic (PV) inverters are proposed. In this strategy, instantaneous real and reactive power are calculated respectively by using voltage and current components with specific frequencies. Then a maximum power point tracker (MPPT) technique is integrated with the strategy to maximize PV generation. Simulation results demonstrate the effectiveness of the proposed strategy. Keywords—Direct power control, photovoltaic generation, phase-locked loop, SVPWM, single-phase H-bridge inverter