Research On Control Strategy Of Low Voltage Microgrid Based On Droop Control

Micro-grid is considered as a power source and effective tool to construct the third generation power grid in the future. The control strategy of micro-grid, which can achieve high reliability, high redundancy and scalability of the whole power system, plays an important role in micro-grid technology. In this paper, the traditional P-V droop control strategy is analyzed, improved, simulated and experimental for low voltage microgrid. The specific research contents are as follows.First of all, the structure and principle of PV system and energy storage system are analyzed, and their models are established. PV system use P&O method to achieve MPPT, and use boost circuit to control and increase PV output voltage. Charging and discharging control of battery can be realized by using bidirectional converter in energy storage system. The simulation results show that the PV system and the energy storage system can ensure the stable output of the DC voltage, which can be effectively used in the control strategy of micro grid.Secondly, on the basis of analyzing the principle of the traditional droop control method, the MATLAB/Simulink software is used to build the traditional P-V droop control strategy model. Power would be difficult to allocate accurately and the systems would be easily influenced by loads fluctuation in traditional P-V droop control, two aspects of this strategy are improved. First, droop coefficient self-regulating section is utilized in droop controller, power allocation is achieved by adjusting droop coefficients dynamically. Secondly, the simplified emotional intelligent controller is utilized in outer voltage loop, which has the ability of parameter self-learning. The simplified emotional intelligent controller is utilized in outer voltage loop. The parameters can be adjusted according to the change of the controlled object, which can enhance the anti disturbance ability and improve the dynamical and static performance.Finally, simulation analysis and experimental verification of P-V droop control strategy are carried out. The microgrid simulation model includes the PV system and energy storage system is built. The improved P-V droop control strategy is compared with the traditional P-V droop control strategy in the simulation. The simulate result shows that the power share capability, anti-jamming capability, dynamic performance and steady state accuracy of the improved P-V droop control strategy are better than the traditional strategy. Experimental platform of droop control strategy based on dSPACE is built. Programming and testing of P-V droop control algorithm for two DG are realized by dSPACE, and control the real object. The experimental results show that, the micro grid system with droop control strategy can realize the parallel connection and power allocation.