Research On The Ability Of Supercritical And Ultra Supercritical Unit To Participate In Primary Frequency Regulation

With the increasing scale of power grid, the applications of large millions of supercritical and ultra supercritical units in power plants also grow gradually, the power grid operation is facing more risks and challenges, the stability of power grid frequency is particularly important, which puts forward higher requirements to the units' ability to participate in grid primary frequency control. Based on mechanism modeling method, this paper sets up the power plant control system model of supercritical unit under different loads by analyzing the thermal storage structure and dynamic characteristics of the unit, to reflect the actual control process unit, in order to provide a platform for improving the capability of supercritical unit to participate in primary frequency regulation, and this paper analyzes the ability the new technology for the condensate throttling to participate in primary frequency control.Through mechanism analysis and reasonable assumptions of the supercritical units of the thermal storage capacity, and according to the lumped parameter method,this paper establishes a pressure node model of supercritical once-through boiler. And the design data and the operating data of three typical conditions of the 660 MW supercritical unit are used to calculate the parameters of the lumped parameter model.Then through combining with dynamic mathematical model of double overshoot supercritical steam turbine, and using Simulink software of the toolbox of MATLAB, it establishs the ultra supercritical power plant control system model. In order to ensure the amount of water supply and the fuel quantity invariant conditions, under the three conditions of turbine power and main steam pressure governing valve of step response simulation tests are done. The once primary frequency regulation step signal, random signal simulation experiments are conducted on the two different conditions respectively, and the results show that the simulation results are good to the two conditions. At last, the field data of a power plant with a AGC action is selected and the load response is good. These results indicate that the control system model of the supercritical thermal power unit is applicable to the application of primary frequency modulation as well as the validity and rationality of this model.For most of the supercritical units, their heat storage capacity is small, and theyusually deal with the peak shaving or primary frequency regulation by valve throttling action, but valve regulating ability is limited, making it difficult to effectively play the primary frequency control ability. This paper describes the principle of condensate throttling, and analyzes the dynamic characteristics of the condensate throttling, and combines with the operating data and design data of three typical operating conditions of the 1000 MW ultra supercritical unit in a certain power plant, and then analyzes the load maximum capacity of condensate throttling theoretically. Then, the primary frequency regulation experiments are carried out in the #7 and #8 units of Shanghai Waigaoqiao third factory, which condensate throttling in the frequency regulation is feasible and has great significance for improving the ability of ultra supercritical unit to participate in primary frequency regulation.