Study On MPPT Strategy And Hybrid Energy Storage System Of Independent Photovoltaic Generation

With the increase of fossil fuel consumption, the worldwide energy shortage and environmental pollution are being aggravated. Solar energy as a clean, safe, durable and reliable green energy is becoming a hot spot of research and development. And the stand-alone photovoltaic power generation system has a broad market in rural and remote areas of our country because of the advantages of its economy, simplicity, flexibility. This paper is mainly to do in-depth analysis and research on the maximum power point tracking (MPPT) and hybrid energy storage technology of stand-alone photovoltaic power generation systems.Firstly, this paper introduces the structure, principle and working characteristics of photovoltaic cells, a mathematic model of the photovoltaic cells has been established. As to do in-depth analysis and research on maximum power point tracking algorithm of Photovoltaic array, a novel method of variable-step increment conductance (INC) is given. On the basis of traditional incremental conductance method, the simulation and experiment results prove that the algorithm is feasible, which not only improves the speed of maximum power point tracking, but also improves the stability of the maximum power point tracking, and reduces the power loss.Energy storage part of Photovoltaic power generation system is crucial. In this paper, the generalization and summarization of research focus and achievements are given. On the basis of previous studies about energy storage system which is consists of the super capacitors and battery. The method realizes zero current and zero voltage shutting off of the transistors, eliminates the switching power loss by connecting battery and super capacitors with the new Bi-directional soft switch DC-DC converter. Hybrid energy storage system which makes full use of the high density of battery energy, the high power density and the long cycle of super capacitors, and so on, improves the performance of the energy storage system obviously.Finally, a3KW stand-alone photovoltaic power generation platform has been designed, the BOOST voltage converter is chosen and the hardware circuit of the system is design. The circuit component selection and parameter calculation is introduced in detail. The DSP chip TMS320LF2812is selected as the control core. The real-time monitoring for independent photovoltaic power generation system is continually operating. The experimental results show the availability of the device.