Parallel Operation Of AC Microgrid Stability Controllers

In recent years,microgrid has gained rapid development with its unique advantages.The energy storage devices in the microgrid provide voltage support for the system during the operation of the microgrids and are used to restrain the fluctuation of the injected power from the distributed power supply to the grid when the microgrid is connected to the grid.In this paper,Network stability controller.When more than one microgrid controller is running in parallel,it is the key to stabilize the microgrid operation that all microgrid stability controllers allocate power according to their capacity.The traditional droop control is used for the parallel operation of the microgrid stabilization controller.There are several problems:First,the impedance of the energy storage inverter to the busbar is almost purely inductive or purely resistive to realize the active power and reactive power Decoupling control;the second is the droop control of poor control,the bus voltage frequency and amplitude are biased;Third,the difference between the line impedance so that the power can not be fully in accordance with the inverse of the set droop coefficient to be assigned,droop coefficient design can also cause system instability.In this paper,we first establish a mathematical model of microgrid stabilization control,and compare and analyze two control strategies for a single microgrid stabilization controller.The main circuit parameters and controller parameters are designed.The factors that affect the rational distribution of power in droop control are analyzed.The power loop of droop control is modeled by small signal,and the influence of droop coefficient and line impedance on system stability is analyzed.An improved droop control strategy based on virtual resistor is proposed:the synchronization pulse is used to keep the steady state of each microgrid controller in phase with the output voltage,and the system frequency is stabilized at 50Hz without fluctuation with the load;the traditional droop control Power outer ring,through the virtual resistor so that the stability of the micro-grid controller in accordance with the inverse of the virtual resistor to allocate power,when the virtual resistor value is larger,you can eliminate the impact of line impedance differences.The introduction of virtual resistors to achieve a reasonable power distribution but also to the bus voltage amplitude deviation,so the bus voltage RMS feedback voltage secondary voltage regulator measures.The physical meaning of this control strategy is clear,the realization is relatively simple,and has certain practical significance.Finally,the validity of the control strategy is verified through simulation.A parallel experiment platform based on TI TMS320F288335 chip is set up in the laboratory,and the control strategy is verified.