Research On The Coordination Control Strategy Of The Master Inverter Applied In Integrated Photovoltaic And Energy-storage Micro-grid

The concept of Distributed Generation(DG) is proposed because of energy crisis and environmental problem. Solar energy accepted as a clean, inexpensive and renewable energy, is widely applied in DG system. Because of uncontrollability, the DG is difficult to be applied in large scale. As a result, the Micro-grid is proposed. In order to keep the power balance within the Micro-grid both in grid-connected mode and island mode, the energy storage equipment is an indispensable unit of the Micro-grid. So the research on the coordination control strategy of the integrated photovoltaic and energy-storage Micro-grid has important significance.The structure of the integrated photovoltaic and energy-storage Micro-grid used in low power applications is shown in this paper, and the PV module and the battery are both connected to the system only by a two-stage inverter. The coordination control strategy is proposed based on the structure, including the control of the grid-connected mode and the island mode. In view of the master inverter of the integrated photovoltaic and energy-storage Micro-grid, this paper builds the model of the maximum power point tracking on the primary Boost circuit; the models of the inductor current loop, the battery charging and discharging loop and the voltage loop in the island mode of the three-phase full bridge inverter, as the second stage of the Micro-grid inverter. For the stability analysis of the Micro-grid, the two modes of the Micro-grid are studied separately by the Eigen-analysis method. The sensitivity of the grid inductor and the current(voltage) loop parameter to the characteristic root is analyzed. And the Eigen-analysis method is also applied to compare the stabilities of the inverters based on different current feedback schemes including inductor current feedback and grid-connected current feedback. A 15 k VA Micro-grid inverter is designed and built to evaluate the coordination Micro-grid control strategy. And the related experimental results are depicted to verify the steady operation and dynamic transition of Micro-grid inverter.