Control method and system for primary frequency modulation of thermal power generation unit

Abstract

The invention discloses a control method and system for primary frequency modulation of a thermal power generation unit. The method comprises steps as follows: frequency modulation capability parameters of a steam turbine control valve are acquired; according to the frequency modulation capability parameters of the steam turbine control valve, a control valve frequency modulation threshold value of the power generation unit in a frequency modulation range of plus-minus 11 r/min is acquired; whether grid frequency exceeds the control valve frequency modulation threshold value under current working conditions is judged; if the grid frequency exceeds the control valve frequency modulation threshold value, primary frequency modulation is performed in a mixed frequency modulation manner for controlling the opening degree of the steam turbine control valve and controlling the opening degree of a feed-water bypass; and if the grid frequency does not exceed the control valve frequency modulation threshold value, primary frequency modulation is performed in a control valve frequency modulation manner for controlling the opening degree of the steam turbine control valve. The opening degree of the feed-water bypass and the opening degree of the steam turbine control valve are controlled for simultaneous operation, the requirement for primary frequency modulation of the unit is met, the frequency modulation manners are selected according to actual conditions, the opening degree of the steam turbine control valve is involved in both manners, the requirement for the rapid response to primary frequency modulation can be met, and the problem that primary frequency modulation responding capability is reduced due to restrictions of boundary conditions in the condensation water throttling frequency modulation process is solved.

Description

technical field [0001] The invention relates to the 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] Thermal power generation is the main power generation method in my country, and its load scheduling has a great impact on the cost of power generation. [0003] At present, the available ways for thermal power units to change the load include changing the combustion of the boiler and changing the opening of the steam turbine. Among them, changing the way of boiler combustion is the fundamental way to adjust the output of the unit. This method has a certain delay, but it can continuously change the load of the unit. Adjusting the steam turbine valve can quickly change the load through the adjustment of heat storage, but it does not have energy continuity. The primary frequency regulation function is one of the important means to maintain th...

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Problems solved by technology

Therefore, it is difficult to simultaneously meet the requirements of the power grid for the primary frequency regulation capability of the unit when the frequency difference is large and the requirements for the economical operation of the unit on the power supply side only by adjusting the steam turbine control gate.

As for the use of unit heat storage, in addition to adjusting the steam turbine valve, the current methods of using unit heat storage include the following means: changing the condensate flow rate to squeeze out the low-pressure heater to extract steam, which actually uses the high-grade working fluid in the deaerator The energy difference after replacing the low-grade working fluid in the well causes the follo

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