Research On The Application Of Flywheel Energy Storage To Direct Air-cooled Unit Flexibility

With the rapid development of China’s power industry and urgent need for environmental protection of the society,the development of clean energy has entered a new era.The share of intermittent energy such as wind power and solar power is increasing,but its randomness also brings new challenges to grid frequency control.However,the flexibility of gas-steam combined cycle units and hydropower units is poor,and cannot meet the demand for peak and frequency modulation.Nuclear power units mainly carry basic load due to issues such as fuel efficiency and energy saving and emission reduction policies.Therefore,as the main body of my country’s energy system,coal-fired units have assumed the responsibility of stabilizing the power grid.Its flexibility,especially the ability to adapt to grid load fluctuations and quickly track frequency changes,has become crucial.At present,the frequent peak and frequency modulation of coal-fired units has severely reduced the safety and economy of unit operation,and there is great pressure on meeting the requirements of frequency modulation.For this reason,it is necessary to actively use advanced energy storage technology to improve the frequency adjustment capability of the unit,thereby reducing the pressure on the power grid.The flywheel energy storage system is very suitable for auxiliary coal-fired unit frequency adjustment due to its high power density,fast response rate,high charging and discharging efficiency,and low environmental pollution.The application of the flywheel energy storage system also can stabilize the output power of the unit,and improve the safety and economy of the unit’s operation.Therefore,it has important practical and guiding significance for the application research of flywheel energy storage system to assist the flexibility of coal-fired units.This article first introduces the difficulty of peak and frequency modulation of thermal power units and the necessity of flexible transformation,as well as the current research status of flywheel energy storage.Then,the working principle of the flywheel energy storage system and its advantages of participating in the frequency regulation of the power grid are introduced in detail,and a simulation model of the coal-fired unit coupled flywheel energy storage system is established in MATLAB/Simulink.Next,taking a 600MW direct air-cooled unit of a certain power plant as the research object,aiming at the problem of increased back pressure and limited flexibility of the unit due to high ambient temperature during the summer high temperature period,Set the corresponding load disturbance command to study the improvement of the flexibility of the unit after coupling 6MW and 8MW flywheel energy storage systems through simulation.Finally,the heat generation mechanism and heat dissipation of the flywheel energy storage system used in the power plant in the actual operation process are analyzed.In view of the water-saving needs and the special weather conditions in summer of the northern region,a closed-loop cooling water and air-cooling heat dissipation plan for the 8MW flywheel energy storage system was designed.Then this article introduces the selection of heat exchangers,design calculations and the selection of auxiliary equipment of each link in detail,and discusses the actual operating effects of the cooling system.