Study On Load Frequency Control Strategy Of Multi-area Interconnected Power System With Hybrid Energy Storage System

The development degree of electric power industry is an important index to measure the level of national economy and national security.As an important trend of modern power system development,multi-area interconnected power system has some advantages in reliability,economy and stability.Ensuring system stability and the quality of the output power is the key to grid operation.The quality of power system output power depends on voltage and frequency.Grid frequency control is an important control problem in power systems.This paper seeks to find effective design solutions to improve the frequency control of multi-zone interconnected power systems.Considering the limitations of improving the control algorithm of the internal load frequency controller in the power system,this paper designs a scheme to improve the dynamic performance and stability of the system by introducing HESS to traditional multi-area interconnected LFC system.First of all,this paper introduces the development status of multi-area interconnected power system and hybrid energy storage systems(HESS)at home and abroad.The basic concepts and control objectives of LFC are summarized.The research status of load frequency control strategy in power system is summarized.Various problems and challenges in the research of this subject are analyzed.Secondly,the basic composition,structure and working principle of HESS are analyzed in detail.The model and simulation of active parallel hybrid energy storage system(APHESS)are established.Low-pass filter is used to distribute the output power of battery and supercapacitor in APHESS.PID control is used in B and SC part to enable APHESS to release/absorb electric energy according to the target power instruction issued by power grid.Based on the Matlab/simulink platform,the simulation results show that the APHESS designed in this paper can accurately follow the target power output,which verifies the feasibility of the design scheme.Then,the article analyzes the advantages and disadvantages of different topologies and inter-area networking methods for multi-area interconnected systems.The linearization expressions of each unit in the system and the linearization model block diagram of the LFC system are obtained by linearization of the system at a certain operating point.The basic process of power system frequency modulation is described.A state space model is established for an independent single-area LFC system and the multi-area interconnected LFC subsystem after the application of APHESS.A fully coupled four-area interconnected LFC system simulation model is built.The experimental results verify the correctness of the model.Finally,the paper studies the H_?robust frequency control strategy based on LMI and designs an external closed-loop controller for the multi-area interconnected LFC system after the introduction of APHESS to control the load frequency again.In order to fully study the coupling problem caused by system interconnection and the uncertainty caused by external load disturbance,the simulation uses the new fully coupled four-area interconnected LFC system as the specific research object.Using the classical PID control theory and robust control theory,which are widely used in practical engineering,the distributed H_?robust state feedback controller and PID output feedback controller are designed to calculate the active power provided by APHESS in real time.The simulation results show that the proposed design can effectively improve the frequency control effect of multi-region interconnected systems and has certain practical engineering significance.