Unified Control For Three-Phase Photovoltaic Grid-Connected And Active Power Filter

As the world energy crisis and environmental pollution problems become more and more serious, solar energy for its clean, environmental protection, and inexhaustible advantages, has become the most promising new energy. Photovoltaic generation is a kind of main form in the aspect of using solar energy effectively, and it has become the main trend in the photovoltaic system. At the same time, with the industry speed-increasing, a lot of impact and nonlinear loads has became in recent years, and it bring about serious harmonics pollution and big current of reactive power which has caused serious pollution in the aspect of the public power grid power quality.In this paper, the development and the obstacles of two kind’s technology about photovoltaic grid-connected power generation and active power filter are introduced. By comparing the structure and control rate between the PV grid generation and active power filter technology, we find that both have the similarity. At the same time, PV grid power generation device is impacted by the external environment, when the device works intermittently, it reduces system utilization, and when it cut frequently, it reduce the stability of the utility grid. so, Take into account the deficiency and the similar about them, this article puts forward the three phase photovoltaic grid-connected power generation with the unity of the active filter control concept, that it can compensate harmonic and reactive current in the power grid,at the same time it also implement PV grid power generation. So the multi-usage, save investment can be realized. At the same time it also improves the utilization rate of the whole of the PV grid power generation systems.This paper mainly analyzed the theoretical foundation that the three-phase photovoltaic (PV) grid generation and active filter can be unified control. And we find the two key technology of unified control system are the Maximum power tracing and harmonic and reactive current detection technology. First, this paper established the mathematical model of PV cells, and analyzed output power along with the change of sunshine intensity and temperature; we find that the output power has nonlinear characteristics. Based on the insufficient of the traditional maximum power tracking algorithm, an improved maximum power tracking algorithm is proposed. Based on the insufficient of the analysis of traditional p, q method to detect the harmonic and reactive current defects, we put forward the concept through using the ip, iq method. Secondly, through the contrastive analysis of the current tracking control methods, in this paper, the current tracking control is realized by using the space vector control method, a corresponding PWM inverter control work. Finally, by using MATLAB of SIMULINK module, it has built the three-phase photovoltaic (PV) grid power generation system and the active filtering unified control system dynamic model, Based on the results of the simulation analysis, it illustrates that the disturbance observation method has improved the accuracy of MPPT, it has achieved the suppression of harmonic and the effectiveness of power compensation. At the same time, it proves that the unified control system is correctness and feasibility.