Research On Optimal Operation Control Technology Of User-side Microgrid

With the increasing depletion of traditional fossil energy and the intensification of environmental pollution problems,more and more renewable energy is connected to the power grid in the form of distributed power generation units,but its own volatility and uncontrollability are not conducive to distribution Large-scale access to power supply.The microgrid can solve the contradiction between distributed power generation and the large power grid,and realize the widespread construction and access of distributed power on the user side,to improve the power supply flexibility and reliability of the distribution system.Most distributed power sources in the microgrid need to be accessed through the interface of power electronic components,and the corresponding control strategy determines whether the microgrid can operate stably.This paper mainly studies the operation control and power optimization of the user-side microgrid.First,based on the topology and mathematical model of the inverter and chopper,the operation mechanism is analyzed and the power control algorithm is deeply studied.By selecting a reasonable operation control method,the power can be accurately adjusted in the user-side microgrid.Secondly,the traditional droop control principle and droop control characteristics of the distributed power interface inverter are studied.At the same time,the droop control applied to the low-voltage microgrid on the user side is analyzed,and the realization of the droop control strategy based on f-P and U-Q characteristics is given.The operation modes of the user-side microgrid under the peer-to-peer control system are analyzed in detail.Simulation verification shows that the user-side microgrid based on droop control can ensure reliable power supply to users.Next,in the user-side microgrid parallel system using traditional droop control,due to different line impedances and local loads,complicated logic of the control unit,and differences in control parameter settings,the reactive power output of each distributed power supply cannot be divided equally,So reactive circulation occurs.To solve this problem,an improved distributed power supply parallel droop control strategy is proposed.Reactive power compensation is added to the traditional U-Q droop control to effectively improve the reactive power distribution accuracy of the distributed power multi-machine parallel system and reduce the system circulating current.Aiming at the characteristics of the user-side microgrid with multiple distributed power sources connected in parallel on the DC bus side,a parallel control method for multiple distributed power sources with active droop control on the DC side is proposed.The active droop control is applied to the DC side chopper link separately,and the reactive droop control is applied to the AC side single converter link,which reduces the system power coupling while ensuring stable system operation and reliable power supply to users,And avoid the generation of reactive power circulation.The effectiveness and feasibility of the optimized operation control strategy of the user-side microgrid multi-machine parallel system are verified by the Matlab / Simulink simulation platform.