Research On Voltage Stability Control Of Isolated Dc Micro-Grid Based On The Energy Storage

Micro-grid is conductive to the utilization of centralized distributed generation at small capacity, as an independent whole. Compared with the traditional power distribution network, the structure of micro-grid is relatively flexible and the form of micro-grid is various, which has obvious dominance for better utilization of renewable energy sources such as wind and solar whose power output are affected by the limits of natural resources. In recent years the DC micro-grid, which has many advantages such as less energy transform link, high efficiency of the system and easy to control, is widely concerned by scholars at home and abroad.As DC bus is energy exchange intermediary of DC micro-grid system, a constant DC bus voltage has a great significance to the energy transformation and stable operation of DC micro-grid system. Without power grid support, renewable energy sources such as photovoltaic and wind power supply instable, isolated operation DC micro-grid system. Thus energy storage devices will be needed to maintain the bus voltage stability and balance the instantaneous energy. In this paper, isolated operation DC micro-grid system is constructed from the typical structure of DC micro-grid, and the simulation model of the system is constructed on MATLAB/Simulink platform. A typical dual-loop control method based on battery storage voltage regulator is researched and the mathematical model and stable operation condition of the system are analyzed. The bus voltage stability is improved by optimizing the system parameter and controller parameter.To a certain extent, the dual-loop control method based on battery storage voltage regulator can maintain bus voltage stable, but DC bus voltage may be still impacted under large disturbance. Due to DC bus voltage disturbance mainly comes from the system power fluctuation, a kind of power feed forward compensation method is presented, which use composite correction method based on the disturbance compensation of cascade control. The control structure and control method are analyzed and researched. The power feed-forward loop is added to the feedback control loop of the system. It constitutes a system combination of feed-forward control and feedback control. Theoretically, the influence of power disturbance can be completely eliminated by this control method. The simulation results show that the bus voltage fluctuation with the system power can be more effectively smoothed or inhibited by using this method.Finally, two control methods are verified by the contrast experiment on the dSPACE experimental platform of isolated operation DC micro-grid system. Experimental results show that, on the basis of dual-loop voltage stability control, the bus voltage fluctuation is obviously inhibited and the system stability is effectively improved after adding power feed forward compensation control.