Control method and system for primary frequency modulation of thermal generating units

Abstract

The embodiment of the invention relates to the technical field of thermal power generation control, and provides a control method and a system for primary frequency modulation of thermal generating units. The control method comprises the following steps: a frequency difference of a power grid is obtained; it is determined whether the reduction amplitude of the power grid frequency exceeds a presetrange according to the frequency difference of the power grid; if not, the primary frequency modulation based on boiler energy storage is performed on the units; and if so, the primary frequency modulation based on a feedwater bias optimization logic and a condensate throttling optimization logic is performed on the units; wherein, the feedwater bias optimization logic is used to increase the feedwater quantity of the boiler; and the condensate throttling optimization logic is used to reduce the opening degree of a water valve on a deaerator. In the embodiment of the invention, when the frequency of the power grid decreases greatly, the main steam pressure and the work capacity of working medium are improved by the two methods of increasing the feedwater quantity through the feedwater bias and reducing the condensate flow through the condensate throttling; steam extraction capacity of a turbine is reduced to improve the work of the working medium; and the frequency modulation accuracyand amplitude of the primary frequency modulation are improved.

Description

technical field [0001] The invention relates to the technical field of thermal power generation control, in particular to a control method and system for primary frequency modulation of a thermal power generating set. Background technique [0002] The grid frequency reflects the balance relationship between the power generation on the power generation side and the power load on the power consumption side. When the generated power is equal to the electric load, the frequency of the grid is stable; when the generated power is greater than the load, the frequency of the grid increases; when the generated power is smaller than the load, the frequency of the grid decreases. The grid frequency is an important quality index for evaluating power quality, which is related to the safety and reliability of the grid. Therefore, ensuring the stability of the grid frequency is an important task for the operation of the power system. According to the adjustment range and adjustment abilit...

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Problems solved by technology

However, under the condition of large frequency difference of power grid frequency accidents, thermal power units are required to participate in the primary frequency modulation load adjustment range, and the frequency modulation lasts for a long time. Large frequency difference FM requirements

Moreover, the current thermal power units are mainly super (ultra) critical units. Since the once-through furnace boilers of the ultra (super) critical units have no steam drums, the heat storage capacity of the boilers is limited, so the capacity of the units to change loads is insufficient.

In addition, in order to improve the power generation efficiency, the ultra (super) critical unit generally adopts the sliding pressure operation mode, and the opening of the steam turbine high pressure control valve is relatively large during normal operation, so the adjustable margin is more limited

[0006] Therefore, the traditional primary frequency regulation control strategy of super (super) critical units cannot meet the requirements of safe and stable operation of the power grid under the new situation

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