Research On Operation Control And Distributed Resource Of MicroGrid

Microgrid is a kind of power grid integrating part of small distributed power generationsand local loads. As an important part of smart grid, microgrid is not only an effectivecomplement of traditional grid but also an efficient form of using distributed power, besides,it is an important way to vigorously develop renewable energy sources, improve reliability ofpower supply, and expand power supply system capacity.As the core of the microgrid system, inverter is required to output high qualitywaveforms of voltage. After the control method of the inverter is theoretical analyzed, theouter voltage loop and internal current loop are used in the double closed loop control system,and the disadvantages of slow dynamic response and weak bandwidth control force of theinverter are improved, meanwhile, the parameters selection of the control system and LCfilter are derived. According to the analysis of the dual-loop control inverter and outputwaveforms, it has been shown that the control method can meet the requirements of themicrogrid system.An efficient and stable control system plays an great important role in normal operationof microgrid. In this paper, three kinds of typical control strategy of microgrid including P-Q,V/f, and Droop are analyzed, and the corresponding control process based on control theory isgiven. The power split problems in shunt-wound distributed power source, master-slavecontrol, and peer-to-peer control method in microgrid. The single distributed power sourceand multi-distributed power source with different capacity are made to operation stably in thegrid-connected mode and islanded mode.Smooth transition between grid-connected grid mode and islanding mode is the coremeans of microgrid system to enhance its reliability. According to the relationship betweenthe output voltage and grid voltage when microgrid is operating in islanding mode, PLL isused to detect the micro power source, as well as voltage and phase of large power grid, the micro source can adjust the grid voltage, phase, frequency by means of droop control, thesmooth transition between grid-connected grid mode and islanding mode smooth is achieved.Considering the complexity and limitations of establishing an microgrid experimentalsystem, the microgrid simulation examples are established by using Matlab software, thesingle micro source and multi-micro source operating in both grid-connected grid mode andislanding mode as well as smooth mode transition are simulated and analyzed, and themicrogrid operation characteristic waveforms are obtained, the simulation results conform tothe theoretical research, verifying the correctness of the control strategy, which has certainguiding significance to practical application.