Primary frequency modulation control system adopting feed-water throttling and control method of primary frequency modulation control system

Abstract

The invention provides a primary frequency modulation control system adopting feed-water throttling and a control method of the primary frequency modulation control system. When the power grid frequency is reduced, the primary frequency modulation demand is rapidly responded to maintain power grid stability. The method comprises the steps that a, turbine rotating speed signals, unit load signals,economizer inlet feed-water temperature signals and power grid real-time frequency signals are collected; b, the deviation of a first turbine rotating speed and a second turbine rotating sped is calculated, the variation amount of the actual load of a unit is determined, and the frequency modulation load set value of the unit is determined; c, a frequency difference signal is calculated, when thefrequency difference signal is smaller than 0 and exceeds a primary frequency modulation dead zone, the opening degree theoretical value of an adjusting valve of a feed-water bypass control loop is calculated, a first modification value of the opening degree theoretical value is calculated, a second modification value of the opening degree theoretical value is calculated through a PID controller,and a third modification value of the opening degree theoretical value is calculated according to the economizer inlet feed-water temperature signals; d, the opening degree set value of the adjustingvalve is calculated; and e, the opening degree of the adjusting valve is adjusted according to the opening degree set value to control the feed-water quantity of a feed-water bypass.

Description

Technical field [0001] The invention relates to the technical field of control systems for thermal power plants, in particular to a primary frequency modulation control system adopting water supply throttling. Background technique [0002] With the gradual increase in the number of domestic thermal power units, in order to ensure the stability of the grid frequency, the commissioning units require a frequency modulation. One-time frequency regulation means that the generator set automatically increases its own load when the grid frequency drops, and automatically reduces its own load when the grid frequency increases, thereby limiting the change of the grid frequency. According to relevant national regulations, when the grid frequency exceeds 50±0.033Hz, that is, when the unit rotates at 3000±2r / min during normal operation, the response speed of the unit's primary frequency modulation must meet: the coal-fired unit reaches 75% of the target load for no more than 15s. The time of...

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Problems solved by technology

[0004] Coordinated control of boilers and steam turbines responds to grid frequency changes. The increase or decrease of fuel will cause too much disturbance to boiler combustion. In addition, the pulverizing system of the unit has a large inertia and delay and cannot quickly respond to load changes. At the same time, in order to ensure the adjustment margin of the steam turbine, The main steam regulating valve cannot guarantee the fully open state, which reduces the efficiency of the unit

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