Evaluation And Improvement Of Primary Frequency Modulation Capability Of Thermal Power Unit Based On System Identification

The proportion of new energy generation grids such as wind power and photovoltaic power generation is gradually increasing.The random fluctuations caused by this have put forward higher requirements for the stability of grid frequency.The requirements of traditional power systems for controllability and safety.Increasingly.At present,large-capacity thermal power units are the main source of power grid frequency modulation.The frequency modulation capability of the unit is an important support for the coordinated development of network sources.In recent years,the"Regulations on the Administration of Auxiliary Service Management of Regional Power Grid Power Plants" and the ""Regulations on the Operation of Grid-Connected Operation of Regional Power Plants" promulgated by various regions("two rules")clearly require that thermal power plants should provide and undertake primary frequency regulation of the power grid.The responsibility and obligation of the generator set is more strict.The majority of the units can meet the requirements of the assessment.However,there are still insufficient indicators such as the correct rate of correcting the frequency of the primary frequency modulation and the contribution of the power.Therefore,it is necessary to thoroughly study the frequency modulation capability of the unit to meet the assessment requirements.Based on the historical operation data of a 350MW supercritical thermal power unit,this paper establishes a steam turbine and speed control system model,and builds a simulation platform for studying the primary frequency performance of supercritical thermal power units,and analyzes its primary frequency modulation margin.Were studied.main tasks as follows:Establishing a steam turbine and speed control system simulation model,including model framework establishment,data processing,parameter identification and model verification.The working principle of each typical link of steam turbine and its governing system is analyzed,and the mathematical model of steam turbine and its governing system is established.The required model parameters are obtained by systematic identification of historical operational data.Model verification is provided to provide a simulation platform for subsequent analysis of primary frequency performance.Starting from the operating parameters,control parameters and other related factors,the influencing factors of the unit's primary frequency modulation are analyzed.The operating parameters of the unit are mainly selected by the combination of correlation analysis and mechanism analysis.The main influence parameters of the frequency modulation are selected from many parameters.The control system is changed by Simulink,some control parameters are changed,and the test verification is carried out to study the control parameters.The effect of frequency modulation;other factors take into account the measurement accuracy,valve opening,valve flow characteristics changes and the impact of operating mode on primary frequency modulation.Finally,choose the factors that affect the frequency modulation margin.The turbine body model is optimized,and the main steam pressure is introduced to simulate the model.The simulation model is used to obtain the primary frequency modulation margin under fixed conditions.The LS-SVM model is used to extend the primary frequency modulation margin to the full working condition range,and predict the primary frequency modulation margin under all working conditions.And analyzed the change of heat rate caused by a frequency modulation,and made an economic analysis.The primary frequency adjustment margin can monitor the current primary frequency modulation capability in real time,and provides an estimate and reference for the power plant related personnel to judge the frequency modulation capability of the unit when a frequency modulation occurs.The primary frequency modulation action in the existing historical data of the 350MW supercritical thermal power unit is analyzed,and the first frequency adjustment evaluation index is calculated,such as the correct rate of the first frequency modulation action,the power consumption of the primary frequency modulation,and the rate of change of the speed.The evaluation of the primary frequency margin is introduced.Through the analysis of historical data and the calculation of the simulation model,a solution to the primary frequency assessment is proposed,so that the unit can better adapt to the assessment needs.The model of steam turbine and governing system was established by the method of system identification,and the influencing factors of primary frequency modulation were analyzed.Through the limitation of the main steam pressure,the simulation obtains the frequency modulation capability limit of the fixed working condition.Extend the value of the fixed operating condition to the full working condition,and predict the frequency modulation margin in real time.The influence of the primary frequency modulation on the primary frequency modulation performance of the unit should be analyzed.