| The development of the society cannot leave the support of energy, in this context, photovoltaic power generation gradually influences the distribution of the demand for energy. As an important part of photovoltaic power generation systems, photovoltaic(pv) grid inverter, the pros and cons of its performance will directly affect the efficiency of photovoltaic power generation and power quality. Based on the photovoltaic(pv) grid inverter as the research object, research goal is to reduce the energy loss and improve the efficiency of photovoltaic power generation and quality.In this paper, the design of the power of 5.5 kW single-phase grid photovoltaic inverter, using two stage isolation type topological structure, the former adopts the Boost circuit to realize the rise and fall of photovoltaic battery output voltage and maximum power point tracking(MPPT), the second level adopts full bridge inverter circuit to complete the energy transformation and interconnection. This article adopts the double loop of voltage and current instantaneous value feedback control strategy of the inverter output power quality higher single polarity SPWM modulation method, double loop control model is established, the design of each loop compensator, in view of the photovoltaic battery output power mutation to join the feedforward power, improve the system dynamic response; And for the secondary on the dc bus voltage ripple join compensation to counteract the effects of fluctuations of current, improve the quality of inverter output current.In this paper, the photovoltaic battery MPPT control strategy has also carried on the thorough research, based on the analysis of comparing several traditional MPPT algorithm, aiming at the tracking process of energy loss, variable coefficient setting reference initial MPPT algorithm was presented, whose effectiveness is verified by MATLAB, this method can improve the energy efficiency. Island inspection methods commonly used in this paper, the grid inverter are simulated, based on the active frequency shift method(AFDPF), active phase shifting method(APS) and low frequency phase perturbation method(ALFD) after the results of simulation analysis, adopting detection blind area small, fast detection, current THD small island detection method.Through the theoretical research of this paper, the 5.5 kW single-phase grid photovoltaic inverter system design, building hardware experimental platform, the experimental results show that the system design and control strategy in this article, can get high quality inverter output current, current THD meet the system requirements. |
