An AGC Method For Distributed Generation System With Two-channel Random Time Delays

Due to the contradiction between social development and environmental protection,the distributed generation system including clean energy forms such as photovoltaic and wind power has developed rapidly,meanwhile,it also brings new challenges to the safe operation of power system.On the one hand,the regional interconnection characteristics of distributed generation system will increase the amount of interconnected information transmission in networked AGC(Automatic Generation Control,AGC)system,which may lead to the delay of information transmission,packet loss and other problems.On the other hand,the output of clean energy will be affected by the environment,which makes it have the uncertainty of power generation,and this uncertainty of power output will also bring new problems to the traditional AGC.In this paper,a new control strategy based on MPC(model predictive control,MPC)algorithm is proposed to eliminate the negative effects of two-channel random delays due to regional interconnection and uncertainty of clean energy output on AGC control system.Firstly,the basic principle of AGC system is introduced.Through the analysis of the transfer function of each link of AGC,a single-region dynamic model of AGC is established,furthermore,the dynamic model of multi-region interconnection AGC is constructed.At the same time,on the basis of MPC algorithm theory,taking two-area interconnected power system as an example,the AGC system based on predictive control is designed,and the mathematical model of AGC system is constructed.Then,the influence of two-channel random time delays on the AGC system of interconnected power grid is simulated and analyzed,and the negative impact of time delay on the AGC control system is verified.The analysis shows that the AGC system can not guarantee its expected dynamic performance because of the existence of time delay.Due to the loss of sampling data caused by time delay,an selection and optimal processing strategy of time delay based on variable prediction sequence is proposed to obtain appropriate control variables,thereby eliminating the negative impact of two-channel random time delays on AGC system.Thirdly,for the output uncertainty of distributed generation system,taking photovoltaic system as an example,the influence of generation uncertainty on AGC system and its countermeasures are discussed.In order to reduce the negative impact of the uncertainty of photovoltaic generation on AGC system,a cascade correction compensation link is introduced to realize dynamic adjustment in the control process.The dynamic compensation characteristics of cascade compensationlink can not only deal with the uncertainty of photovoltaic power generation,but also improve the system stability and control performance.The research content is simulated and validated on the matlab/simulink simulation platform.On the one hand,the selection and optimal processing strategy of time-delay proposed for two-channel random timedelays can effectively improve the governing speed and control accuracy of AGC system.On the other hand,the introduction of cascade correction compensation link for generation uncertainty in distributed generation system can ensure the stable control of AGC system and improve the stability of AGC system.The simulation results verify the feasibility and effectiveness of the proposed method.