Research On Load Dispatch And Frequency Control Strategy Of AGC In Interconnected

There are many kinds of load disturbances in the power system.Automatic Generation Control(AGC)is widely used because it can balance load disturbances in time.Since the change of the output of automatic generation control unit will bring additional power generation costs and pollutant emissions,how to distribute the load rationally to reduce power generation costs and pollutant emissions is an urgent problem to be solved during the operation of the automatic generation control system.In addition,it is still the most important purpose of automatic generation control to formulate a reasonable frequency control strategy and ensure that the power supply frequency is stable when the load is connected.This paper studies the load distribution and frequency control of AGC in interconnected power system.The main research contents are as follows:(1)First,an AGC in two-area interconnected power system with multiple units in a single area is considered,and its system framework is given.Then,the combined application characteristics of the interconnected power grid are analyzed,and frequency deviation and tie line exchange power deviation are selected as the control objects for the shortcomings of the TBC-TBC control mode.Finally,a dynamic model of a single unit in a single area including governor,steam turbine,generator-electric power system and tie line is established to provide a basis for the subsequent research on load distribution and frequency control.(2)Based on particle swarm optimization algorithm,a load multi-objective optimization distribution strategy is proposed.First,the area adjustment responsibility distribution method is selected by setting the frequency offset factor and the natural frequency characteristic coefficient.Then,considering the economic and environmentally-friendly indicators,a single-area multiple-unit automatic generation control load optimization distribution model is established,and a balanced unit is set to make the unit's output meet the equality and inequality constraints strictly when considering the network loss.Finally,for the problems of local optimality and uneven distribution of optimal solutions in the multi-objective particle swarm optimization algorithm,the optimization coefficient linkage,the introduction of elite crossover operators and sorting based on crowding degree are used to improve it,and the fuzzy membership function is selected to filter the Pareto solution set to get the unique load optimization distribution result.(3)A frequency model predictive control strategy is proposed for the AGC in two-area interconnected power system.First,based on the dynamic model of a single unit in a single area,a dynamic AGC model in two-area interconnected power system is established.Then,the distribution factors are calculated using the optimized load distribution result,and the statespace equations including the distribution factors are further derived.Finally,a frequency model predictive controller is designed to control variables such as grid frequency,area control error and tie line exchange power.On the basis of ensuring economic and environmentally-friendly indicators,it also meets the dynamic control requirements for grid frequency and other parameters.The simulation model of the system is established with MATLAB / SIMULINK,and the load distribution and frequency control strategy proposed in this paper are verified.The simulation results prove the feasibility and effectiveness of the methods and strategies proposed.