Research On Smooth Switching Control Strategy Of Microgrid Double Models Inverter

Since the first industrial revolution, the use of energy is more and more widely, with the rapid development of global economy, energy demand is gradually increasing, today, the energy has become the key factors which restrict the development of the economy, countries around the world have also made different energy strategies. So far, the development of hydropower, wind power and solar energy technology has become more mature, the market has a lot of products in this area. On how to make these more effectively separated due to the influence of regional energy efficiency, researchers put forward the concept of Microgrid.When working in the micro-grid inverter and network operation mode using PQ control strategy, this strategy does not need to build their own control voltage and frequency can be obtained through the distribution network. Expectations of active and reactive power load to get through here when the islands using the measured active and reactive power, so that the original part of the formation of a separate system. In order to avoid micro-grid inverter and can occur when the network voltage shock, and then talk to the paper, the network strategy, micro-grid inverter to run for a period of time in accordance with the parameters of the grid, when the inverter load voltage and grid voltage between the parameters within a small range and then follow the PQ control operation, finally closing.After relatively constant pressure and constant frequency droop control advantages and disadvantages of the two controls, draw droop control is more suitable as a micro-grid control inverter islanding operation. After considering a single micro-grid inverter power supply can not meet the needs of the load, we use more than one micro-grid inverter power to the load in parallel manner, and added to a virtual impedance control circuit, a good solution to the inverter circulation issues. Droop control has an important advantage, can achieve power allocation when multiple inverters in parallel, so you can take advantage of renewable energy sources.Based on the study of dual-mode switch, using the first of the micro-grid inverter and network operation, and then switch to island operation mode, and finally switched to parallel operation mode. After the combination of micro-grid inverter and network operation and theoretical analysis of island operation modes are analyzed in the process of switching voltage mutation causes. To address the impact of changes in the frequency of the system, we use the improved SPLL lock mode, the frequency and phase error is kept within a small range.In the last part of each chapter, through MATLAB/Simulink software for modeling and simulation, simulation results show that the micro-grid inverter and network operation and island operation can meet the requirements, the switching process modes voltage mutation does not appear to reach the expected goals of the research.