AGC Collaborative Optimization Control Strategy For Multi-area Interconnection Grid

The Automatic Generation Control(AGC)system is an important means for modern secondary grid dispatching centers to implement secondary frequency modulation.This type of adjustment method is often referred to as Load Frequency Control(LFC).Load frequency control aims to automatically track the changes o f power system load in real time,maintain the balance between power generation and load power,and keep the frequency of the power system at the specified value,which is an important means to ensure the power quality.Since the beginning of the new century,the rapid development of smart grid technology and Internet technology has made multi-area interconnection a new feature of China's power grid,and research on the use of collaborative optimization control strategies to achieve multi-regional interconnected power grid AGC has become a hot topic.The main research contents of this article are as follows:(1)The significance of the optimal control strategy for automatic generation control of multi-area interconnected power grids is briefly described,an d the research status of the optimal control strategies for automatic power generation control at home and abroad in recent years is described.The large-scale interconnected power grid and the interconnected grid under the intervention of wind power are described,existing issues related to automatic power generation control strategies.(2)Describes the basic principle and system structure of automatic power generation control.Introduces the frequency control mode of the interconnected power grid power s ystem.According to the frequency control mode,the selection of the frequency control mode between the control areas is determined,and a multi-area interconnected power system is built the simulation model.(3)Aiming at the problem of large overshoot an d slow response of AGC in multi-area interconnected power grids in traditional control strategies,a distributed model predictive control strategy is proposed.The mathematical description of the interconnected power system is discretized and its objective function is defined.Taking the three-area interconnected power grid as an example,the state space of hydropower generating units and thermal power units is imported into their respective distributed model predictive controllers,and a centralized model is designed.The predictive controller is compared with the PID controller.The simulation results show that compared with the traditional PID control method and the centralized model predictive control method,the proposed distributed predictive control method has a small overshoot and a short overshoot time.(4)There are non-linear links in the actual operation of multi-area interconnected power grids.For the constraints of the rate of change of the generator constrained link and the position of the val ve,the traditional control strategy has a poor control effect under the influence of the nonlinear link.Consider the model predictive control.The strategy can systematically solve the input constraints,state constraints and output constraints,convert the nonlinear links existing in the automatic power generation control system into constraints on the state of the pair,and use the quadratic programming to obtain the optimal solution under the constraint conditions.For the three-area interconnected power grid with nonlinear links,two controllers of distributed model predictive control and centralized model predictive control are designed.Simulation results show that the distributed model predictive control strategy has obvious advantages in reducing overshoot and improving response speed effect.(5)When wind power is connected to the grid,the volatility and unpredictability of the output power of the wind farm bring problems to the automatic power generation control of the multi-area interconnected power grid.The basic structure and mathematical model of the wind power are introduced,and it is built in the same way as the conventional generating units.Based on the regional interconnected power system simulation model,a distributed model predictive control algorithm is proposed.Taking the three-area interconnected power system as an example,the external load changes of the system are dealt with.The distributed predictive control algorithm designed is compared with a centralized predictive control algorithm.The simulation results show that the distributed model predictive control shows more speed and stability in frequency recovery.Good dynamic performance.(6)Summarizing the work done in this paper,and looking forward to future issues and development trends of automatic power generation control to be further studied.