Research On A Synthesis Control Strategy Of Multi-Source Microgrid And Simulation

As the rising attention of environmental problem, distributed generation has been under consistent development. However, a large number of accesses of distributed generation would have a greater impact on large power grids. Microgrid emerges as the times require. Microgrid through the power electronics interface of micro-power connection to the grid of electricity, which increases the flexibility of micro-grid control. But because system inertia decreases, the difficulty of control of frequency stability and energy balance of the system increases. Therefore, in order to maintain normal operation of microgrid, a good control strategy is essential.Multi-source microgrid is the study object of this paper, and the paper mainly studied the strategies of microgrid control of inverter for micro-power interface. According to the different characteristics of different micro power, we took a different control method, set up a simulation platform of microgrid integrated control. The main work is as following:1. The trial has analyzed the basic characteristics and the fundamentals of grid-connected inverter with different structure, and established the main circuit topology of grid-connected inverter for micro-power interface. Moreover, the parameter design of the LC filter in main circuit is introduced in detail. Combined with main circuit topology structure, the fundamental and the modulation scheme of sine wave PWM technique is expounded. PQ control, and V/F control and the Droop control, which are extensively studied in microgrid, are introduced simply.2. The mathematics model of three phase grid-connected inverter in two-phase rotating coordinate system (d, q) is established in this paper. Furthermore, the basic principle and design method of PQ control are detailed introduced. And the optimization design of parameter of current regulating loop with engineering method is done. Finally, the simulation model of PQ control with micro-power grid-connected inverter is established, to lay a foundation for the establishment of microgrid comprehensive model.3. Droop control is analyzed. Droop control can not be directly applied in low voltage microgrid system. To solve this problem, a droop control strategy based on voltage and current double-loop for distributed generator of microgrid is proposed by introduction of virtual impedance. Finally the simulation model of microgrid with distributed generators is established, and the operation variation of the microgrid are respectively analyzed, when it runs with load changes in islanding mode and runs with the generated power source varied suddenly. The simulation results demonstrate that the control strategy is correct and effective.4. According to the diversity of micro power in the microgrid, build a simulation platform of microgrid integrated control strategy, analyze the operating characteristics of microgrid. The result shows that the simulation model can transform operation mode, micro-power systems with Droop control under islanding operation can give micro-grid frequency and voltage support and take the load power change. The Simulation model provides the foundation.for further microgrid experimental verification.