Research On Modeling And Power Distribution Method Of Modularized Micro-grid System In Island Mode

With the large-scale development and application of new-energy power generation,it is particularly important to make rational use of new-energy generation.A large number of new energy-power generation with decentralized and independent operation has more and more influence on the stable operation of large power grid due to the difficulty of unified scheduling.The micro-grid has greatly alleviated the contradiction between the decentralized new-energy generation and the grid,but there are still many unsolved problems.Therefore,the idea of modular unit of the AC micro-grid came into being.Based on the idea of modular unit,this paper makes a more in-depth study.Firstly,the structure,energy management strategy and control strategy of modular micro-grid with distributed generation,energy storage inverter and local load are described in detail.In this paper,the definition and application scope of modularization of AC micro-grid unit are defined,and the unified energy flow management,energy flow strategy and specific control strategy are described in detail.An improved droop control strategy is proposed to solve the problem that the energy storage link in the unit module can not realize " peak load shaving ".Through the analysis of traditional droop control,it can be known that the output active power of the system is closely related to the frequency.Therefore,the droop coefficient of the energy storage inverter is improved,and the frequency and amplitude of the AC bus voltage in the modular system are introduced,so that when the bus voltage changes,the output power of the energy storage inverter can be affected,and finally the " peak load shaving " of the energy storage system power is realized ?In view of the complexity and many operation modes of the modular micro-grid system studied in this paper,a modeling method based on large time scale decomposition is proposed.The operation mode of the system is decomposed from two-time scales,and then the overall power model of the system is established.Finally,the stability of the system is analyzed by the input-output stability criterion.The system model established by this method can reduce the order,which is more convenient for the stability analysis of the system.Finally,aiming at the whole model of the system and the new control of the energy storage inverter,the simulation is carried out,and a three-level inverter experiment platform using DSP + FPGA as the main control circuit is built,which verifies the correctness of the system control model established in this paper.