Study On Microgrid Control Strategy Based On Wind-Solar-Hybrid Energy Storage

With the continuous development of society, we are facing the dual pressures of non-renewable energy depletion and environmental protection, which make the rapid development of new energy resources. The wind, solar and other distributed power incorporated into the power grid in micro grid has a n important significance, but due to the non-deterministic and random factor in the wind and light, output power of the microgrid has great volatility, which will impact power grid if connected to the grid directly. In addition, power shortfall, shock and vibration will be shown when micro grids switching between the grid operation mode and the isolated network operation mode. So, the domestic and foreign electric power researchers have applied hybrid energy storage system to micro-grid, which has important implications for the enhance of microgrid power supply reliability.Supercapacitor and battery have been applied to wind-solar complementary generation system, micro- grid Micro grid of complementary wind-solar power generation system based on hybrid energy storage is researched in this paper and how to stabilize the output power fluctuation and achieve the scenery of the smooth switching control strategy is studied.First of all, the working principle of each micro source is analyzed and the mathematical models of photovoltaic cell, wind power generation system and hybrid energy storage device is established. Their characteristics are simulated and analyzed by using Matlab/Simulink.Secondly, introducing power allocation strategy based on the correction coefficient of hybrid energy storage device. Design the hybrid energy storage device of power allocation strategy based on the different characteristics between super capacitor and battery. In order to avoid super capacitor due to the energy density to achieve the limit to stop working, this paper introduces the correction factor for corrected the super capacitor output power reference value, and according to the value of the voltage of the super capacitor adjust the correction factor in real time.Thirdly, to optimized the capacity of hybrid energy storage device. Based on the demand of economy and reliability build capacity optimization model of the hybrid energy storage device, and using the improved PSO algorithm to optimize energy storage device capacity; based on the role of hybrid energy storage device in different power allocation strategy design of the DC/DC converter control strategy respectively, in order to avoid overcharge and over discharge phenomenon, join the control of capacitor voltage protection and battery charged state protection; Building simulation model of wind- light hybrid energy storage system, Set up the simulation based on wind speed data from Los Angeles wind farm and light intensity which verify the validity of introduced correction coefficient of power allocation strategy for hybrid energy storage devices used in suppressing the power fluctuations proposed in this paper.Finally, put forward the micro-grid power grid/off- grid switch control strategy based on the hybrid energy storage device. Use of micro-grid model to validation the micro- grid power grid/off- grid switch control strategy based on the hybrid energy storage device, and simulation load fluctuations based on real- time wind- light output for isolated operation verify hybrid energy storage device can maintain the power balance of the isolated operation system.