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Research On Microgrid Load Frequency Control Strategy Based On Multi-Agent System And Active Disturbance Rejection Control Algorithm

Posted on:2020-04-20Degree:DoctorType:Dissertation
Country:ChinaCandidate:X QiFull Text:PDF
GTID:1362330578469920Subject:Pattern Recognition and Intelligent Systems
Abstract/Summary:PDF Full Text Request
As an effective way to solve the integration and control of distributed energy resources,microgrid plays an important role in the current energy reformation.Therefore,it is of great significance to further improve the stability of microgrid system.Frequency is an important index to measure power quality in power system.However,the strong randomness and intermittency of the output of renewable energy generations in microgrid(such as wind turbine generator,photovoltaic power generation system,etc.)greatly reduces system frequency stability,which requires that the power of controllable generation unit in microgrid must quickly track the disturbances of load demand and power generations.Therefore,in order to further improve the microgrid frequency stability,enhance the anti-disturbance ability and robustness,an improved linear active disturbance rejection control algorithm is proposed in this paper.And in order to improve the economy of power generation and realize real-time economic dispatch,various distributed optimal control strategies are designed for different microgrid systems through combining the multi-agent system with linear active disturbance rejection control algorithm.The main innovative researches in this paper are as follows:(1)This paper improves the linear active disturbance rejection control algorithm.The estimated states of linear extended state observer are substituted by the multiple differential of the system output signal,which increases system control accuracy.Subsequently,a load frequency controller for microgrid system is designed based on the improved linear active disturbance rejection control algorithm.In the microgrid model studied in this paper,the variable speed wind turbine generator,diesel generator,solid oxide fuel cell and aqua electrolyzer system participate in frequency regulation simultaneously.The fast response characteristic of aqua electrolyzer system is utilized to compensate and eliminate power deviation timely.And at the same time,this paper designs a "zero setting control loop",which helps aqua electrolyzer system restore to its initial state after participating in frequency regulation.This design can avoid the unnecessary power dissipation.The control strategy can effectively shorten frequency regulation time,reduce frequency fluctuation amplitude,enhance system anti-disturbance ability and ensure system robustness.(2)For the load frequency control and economic dispatch problem in single-area islanded microgrid system,a new distributed optimal control strategy is proposed in this paper,which combines the improved linear active disturbance rejection control algorithm and consensus algorithm based multi-agent system.In this control strategy,system power deviation signal is substituted by the output signal of load frequency controller(or auxiliary controller).Subsequently,this control strategy is applied to a single-area islanded microgrid including wind turbine generators and battery energy storage systems.It can greatly shorten the adjustment time of load frequency control,reduce the fluctuation amplitude of frequency deviation and improve system stability while ensuring system robustness.(3)For the microgrid load frequency control problem with participation of electric vehicles,this paper proposes a new performance index called controllable power rate which is used as the convergence variable to improve the frequency regulation efficiency of electric vehicles and enhance microgrid system stability.By improving the structure of electric vehicle aggregator agent,it can rapidly adjust its output power to compensate the power deviation after the frequency fluctuation.This can also avoid the negative influence of communication delay and distribute the power according to the appropriate proportion.Simultaneously,a parallel multi-agent system is designed for diesel generators to compensate the power change caused by frequency regulation of electric vehicles,so that the electric vehicles can be restored to the initial charging and discharging state and the users' normal charging plan can also be guaranteed.The simulation results indicate that the proposed control strategy can make full use of the fast response characteristic of electric vehicle batteries and improve the frequency stability of the microgrid system.(4)In order to further improve the stability of multi-area interconnected microgrid system,a new distributed optimal control strategy is proposed in this paper,which combines linear active disturbance rejection control algorithm and primal-dual gradient algorithm based multi-agent system.It can effectively combine system dynamic characteristics and optimization process and simultaneously solve the load frequency control problem and real-time economic dispatch.Compared with the existing control strategies,this control strategy can greatly improve system frequency stability and anti-disturbance ability on the premise of ensuring system power generation economy.In other words,it can improve system power generation economy while improving the performance of load frequency control process.So this research has important practical significance.
Keywords/Search Tags:Microgrid system, load frequency control, economic dispatch, distributed optimal control, multi-agent system, linear active disturbance rejection control
PDF Full Text Request
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