Super Capacitor Energy Storage System Grid-connected Inverter New Double Closed Loop Linear Active Disturbance Rejection Control

In recent years,the reform and innovation of the energy system have gradually become the supporting force for my country’s technological and economic development with the rapid development of industry.At this stage,the development of renewable energy in particular has become the focus of research in the energy field,which the recyclable,clean and pollution-free energy is continuously being put into the market and is widely used.Super capacitors have developed rapidly in various industries in recent years,they are widely used energy storage device with many advantages such as fast charging and discharging rates and no pollution.Especially in the field of new energy grid connection is quite extensive,therefore,to ensure the stable operation of the energy storage system after connected grid,which has become an important choice for the efficient use of energy to study and design the control strategy of the energy storage grid-connected inverter and improve its fault ride-through capability.This article first introduces the research background and significance of the super capacitor in detail,and classifies and expounds the current status of domestic and foreign research and development of its grid connection.Secondly,the grid-connected structure of the super capacitor energy storage system is introduced,the mathematical model of the grid-connected inverter in the three-phase static and two-phase rotating coordinate system is theoretically analyzed and structured,and through the model analysis and design the actual control structure diagram of the energy storage grid-connected inverter in this paper.In addition,the transient characteristics of the DC side bus voltage on the energy storage system side and the grid-connected side under stable and fault conditions are analyzed through the law of conservation of energy.Since the energy storage system is a complex system with strong nonlinearity,strong coupling,and susceptibility to grid-side voltage fluctuations,in order to improve its grid-connected steady-state performance,this paper takes the fluctuation of the DC side bus voltage as the control objective,based on the analysis of the performance of the traditional linear active disturbance rejection controller(LADRC),a new type of LADRC based on proportional-derivative control is proposed.Then,in view of the serious phase lag of the new linear extended state observer(LESO)and the weak suppression of high-frequency noise.In this paper,an improved LESO with lead-lag correction link is designed to propose an improved double closed-loop LADRC strategy.Compared with traditional LADRC,the improved LADRC greatly increases the DC side bus voltage when the energy storage system is connected to the grid steady state performance.Finally,this paper takes the super capacitor energy storage grid-connected inverter as the research object,and takes the DC side bus voltage control as the research goal,a simulation model of the grid-connected super capacitor energy storage system is established,and different types and degrees of low voltage ride-through faults are designed on the grid-side,and the effectiveness of the controller is verified by digital simulation.