Research On Optimization Of AGC Parameters And Down-frequency Regulation In Power Market

Frequency is one of the important parameters that reflect the quality of the system.When the balance of the power system is broken,the frequency of the power system will be deviated.This paper briefly introduces the simulation model of the interconnected power grid,and analyzes the changes of the operating point of the interconnected grid under the fluctuation of the two regions,and the relationship between the exchange power deviation of the tie line and the location of the disturbance.Through the analysis of frequency fluctuation principle,a simulation model is established for primary frequency modulation and secondary frequency modulation.The simulation results verify the adjustment characteristics of primary frequency modulation and secondary frequency modulation respectively.Through the simulation of the classic two-region model,the optimal tuning parameters of the PID controller are obtained by the attenuation curve method.The simulation results show that the simulation effect with PID controller is better,and the control effect is remarkable.Further,the dynamic performance and robust performance of the AGC system is improved.Due to the difficulty of the frequency coordination in high voltage interconnection network and the problems of poor tracking performance,difficult parameter optimization and poor optimization effect,a closed-loop feedback automatic generation controller based on simulated annealing and particle swarm optimization algorithm is proposed.The improved optimization algorithm combines the advantages of simulated annealing and particle swarm optimization,and optimizes the key parameters of the controller to minimize the value of area control error,so that the system can recover stably quickly.The simulation results of MATLAB / SIMULINK verify that the closed loop feedback AGC controller with improved parameters can restore the stability of the system quickly and achieve the control effect of frequency coordination when the tie line of the four-machine two-area model fails.Separation of power plants in the electricity market is the main way of commercial operation,and power generation is separated from the power network.As an independent economic entity,power plants belong to different interest groups and have economic trading relationships.Limited to the current situation of imbalance between energy and demand in China,the pattern of transmission networks interconnected by large-scale regional power grids has taken initial shape.In this paper,the three-region interconnected system is taken as an example to derive the frequency deviation,tie line power deviation and area control error expression of the same or different disturbances in the two regions of the three-region interconnected system.The mathematical relationship between the various regions of the system is intuitive.Considering the electricity market factor,based on the existing AGC system model,the AGC model is improved so that the output power of each power generating unit meets the market contract requirements,and the scheduled contract load default and the unit adjustment action characteristics of the generator default are simulated.Further analysis of each parameter response index to verify the dynamic performance and steady state performance of the improved model under different operating conditions.When the regional frequency modulation unit is refused or delayed,it needs to be coordinated by the area interconnected with this area.The uncorrected frequency modulation method still has a certain frequency deviation and tie line power deviation.In this paper,the AGC model state equation is modified,and the ACE and unit adjustment power correction equations are derived.Observing the modified frequency modulation method can effectively make the system ACE indicators within the allowable range,and keep the frequency deviation and tie line deviation always stable at zero,which verifies that the modified frequency modulation method proposed in this paper can achieve good results without error adjustment,and can realize the optimal allocation of the second frequency modulation adjustment amount among the interconnected regions.