Research On Operation And The Influence Of Voltage Stability In Microgrid

With the rapid development of the economy, oil, coal, natural gas and other traditional energy depleted, people need to find alternative sources of energy, solar and wind power generation due to its clean and easy access to the features, to receive widespread attention. The main form of distributed generator have wind power, photovoltaic power generation and fuel cells at present. Microgrid mainly make up by the distributed power generation device, the inverter and its control unit, the energy storage unit and the load. The Microgrid can be connected to the power grid to run. It also can be separately from the large grid to run.This paper studies the distributed generation unit, the inverter control strategy, micro-grid operation, the microgrid voltage stability. Through the Simulink software platform to build the model of direct drive wind turbines, photovoltaic cells and the battery energy storage and photovoltaic hybrid system. Microgrid distributed generation units of the micro-grid in the grid and islanding two modes of health as well as the switching process simulation analysis to study the micro grid voltage stability in these types of cases. Voltage stability problems caused by the fluctuations of wind and solar energy microgrid island operation, an integrated control strategy. After simulation analysis to verify the effectiveness of the control strategy.(1) Elaborate micro-grid PV system, the basic principle of the permanent magnet direct drive wind turbine and battery the three distributed generation unit using the Simulink software to build a photovoltaic cell, two maximum power of the photovoltaic cells The tracking method simulation comparison. Permanent magnet direct drive wind turbines and battery light reservoir simulation model of the hybrid energy storage system, according to the different micro power the power characteristics of each of the various micro-power power output of the simulation analysis, simulation results show that the used herein able to micro-power reaction illumination changes in the actual situation, the wind speed fluctuations, can be applied to the micro-grid simulation modeling.(2) Microgrid inverter three control strategies analysis and research, the derivation principle and control block diagram of the various control methods, these types of control system model in Simulink platform and applied to distributed generation units and network simulation, to verify the effectiveness and feasibility of the control method. Microgrids coordination of distributed power control strategy.(3) The grid voltage stability analysis and research. When islanding, distributed power generation unit using the droop control, wind or light energy changes, the distributed power generation unit to output a corresponding change, but the droop control system power regulation is a droop. A new control strategy is proposed for the problem, droop control and V/f control, both the use of droop control distributed power to achieve the advantages of "plug and play" when the voltage and frequency exceeds a predetermined range when V/f control no difference in regulation.(4) With direct drive wind turbines, photovoltaic cells, light build hybrid energy storage power model of AC Microgrids simulation system, the system, the different types of micro-power using different control strategies. The simulation system in networking mode, islanding mode, as well as networking and silos switch operation, and three cases under the micro-point network voltage stability analysis.