Research On Coordinated Control Strategy Of Microgrid Hybrid Energy Storage System

In recent years,renewable energy power generation has been favored by countries all over the world for its cleanliness and renewability.However,they are highly susceptible to natural environmental factors,resulting in intermittent and random output power.The grid will have a certain impact on the frequency and voltage of the grid.The application of microgrid energy storage technology provides a way to solve this problem.However,there is no device in the existing energy storage device that can combine the characteristics of high power density and large storage capacity.Therefore,it is urgent to find a kind of Hybrid energy storage devices are used to solve this problem and are equipped with appropriate control strategies to improve their performance.Firstly,this paper compares the performance and economy of different types of energy storage devices,determines the hybrid energy storage mode of battery-supercapacitor,and selects the parallel DC/DC converter by contrast analysis.The AC side of the inverter is connected to the grid,and the working principle and circuit topology of the two energy storage devices and the converter used in the control process are analyzed.Secondly,the passiveness of the hybrid energy storage system is analyzed.According to the current transmission form,the circuit structure of the hybrid energy storage system is divided into the AC subsystem and the DC subsystem,and the mathematical model and the PCH model are respectively established.The feedback interconnection method constructs the PCH model of the complete energy storage system.Then,based on the passive analysis and hybrid energy storage system PCH model,the energy shaping control strategy is proposed.The control strategy is realized by the design of grid-connected and off-grid ES controllers,and the control strategy and tradition are implemented.The PI double closed-loop control strategy is compared with the simulation in the off-grid state,which verifies that the control strategy has better speed and robustness.Finally,in order to coordinate the power distribution between the battery and the supercapacitor to optimize the operating state of the battery,this paper improves the acquisition algorithm of the filter time constant based on the traditional filter distribution fluctuating power,and applies the fuzzy adaptive algorithm.In the design of the power distribution controller,the battery life is extended and the simulation is verified.