CN-115395533-B - Method for participating primary frequency modulation and load change of power grid by using gas-electric double-drive unit

CN115395533BCN 115395533 BCN115395533 BCN 115395533BCN-115395533-B

Abstract

The invention relates to a method for enabling a steam-electric double-drive unit to participate in primary frequency modulation and load change of a power grid, wherein the steam-electric double-drive unit comprises a small turbine and an asynchronous motor, when the power grid frequency is lowered to a set first threshold value, the method reduces the steam inlet quantity of the turbine by closing a valve of the small turbine, releases energy storage of extraction steam serving as a steam source of the small turbine, enables more steam to enter a main turbine to apply work, achieves a primary frequency modulation and load change function, and when the power grid frequency is raised to a set second threshold value, increases the steam inlet quantity of the small turbine by opening the valve of the large turbine, reduces the amount of working steam entering the main turbine, and therefore achieves the primary frequency modulation and load reduction function. Compared with the prior art, the invention has the advantages of ensuring the safety and stability of the thermal power unit, realizing economic operation, meeting the primary frequency modulation requirement, being beneficial to further promoting the energy conservation and emission reduction of the thermal power unit, and the like.

Inventors

ZOU KUN
CHE LINGYUN
ZHU JIANFEI
SHEN JIANFENG
WANG XIU
CHEN LIANG
CHEN QI
XU XIAOHUI

Assignees

上海上电漕泾发电有限公司
上海明华电力科技有限公司

Dates

Publication Date: 20260505
Application Date: 20220831

Claims (8)

1. A method for enabling a steam-electric double-drive unit to participate in primary frequency modulation and load change of a power grid is characterized in that the method reduces the steam inlet quantity of a steam turbine by closing a valve of the small steam turbine when the power grid frequency is reduced to a set first threshold value, releases energy storage of extraction steam serving as a steam source of the small steam turbine, enables more steam to enter the main steam turbine to work and achieves a primary frequency modulation and load adding function; When the method is used for loading, the MEH of the small turbine automatically sends out a command, and the steam inlet regulating valve of the small turbine is directly and rapidly closed to a preset opening degree, so that more steam enters the main turbine to apply work, thereby instantaneously increasing the output of the unit and responding to the primary frequency modulation loading requirement; The specific process of loading is as follows: step 1, normally operating a small steam turbine, and determining primary frequency modulation load requirements according to power grid frequency difference and actual output conditions of a unit when power grid frequency drops to exceed a set first threshold value; Step 2, judging whether the steam turbine is within a safety boundary, if so, closing a small steam turbine valve and executing step 3, otherwise, not acting; Step 3, correspondingly increasing a main control instruction of the boiler and increasing the output of the boiler; Step4, after the closing instruction is sent out for a set time, the original extraction steam supplied to the small turbine enters the main turbine to do work, the load of the unit is rapidly increased, and the primary frequency modulation and load adding function is realized; And 5, after the power grid frequency deviation is recovered, adjusting a valve of the small turbine, and gradually recovering the unit to a normal running state.
2. The method for participating in primary frequency modulation load change of a power grid by a gas-electric double-drive unit according to claim 1 is characterized in that when the gas-electric double-drive unit operates, the primary frequency modulation load demand is calculated and determined according to the power grid frequency difference and the actual output condition of the unit when the power grid frequency change exceeds a set frequency difference.
3. The method for participating in primary frequency modulation load change of a power grid by a steam-electric double-drive unit according to claim 2, wherein after the primary frequency modulation load demand is determined, the direction and the amplitude of the action required by the steam inlet modulation valve of the small steam turbine are calculated by combining CCS and DEH side control strategies.
4. The method for participating in primary frequency modulation and load change of a power grid by a steam-electric double-drive unit according to claim 2, wherein when the method is used for adjusting a valve of a small steam turbine, a coordination control system correspondingly changes the adjusted quantity of a main adjusting system of the unit, including fuel quantity, water supply flow and air quantity, so as to quickly compensate the energy requirement of the unit, provide the amplitude and continuous frequency modulation power output required by frequency modulation, and reduce the fluctuation of main parameters of the steam pressure and the steam temperature of the unit.
5. The method for participating in primary frequency modulation and load change of a power grid by using a gas-electric double-drive unit according to claim 1, wherein the turning-down of the gas turbine valve in the step 2 is specifically: calculating to trigger and adjust whether one small turbine can meet the frequency modulation requirement, if so, directly adjusting one small turbine, otherwise, adjusting two small turbines to carry out frequency modulation.
6. The method for participating in primary frequency modulation and load change of a power grid by using a gas-electric double-drive unit according to claim 1, wherein the increasing of the boiler output in the step 3 comprises increasing the boiler fuel quantity, the water supply flow quantity and the air quantity.
7. The method for participating in primary frequency modulation load change of a power grid by using a steam-electric double-drive unit according to claim 1 is characterized in that the primary frequency modulation load reduction function is realized by immediately opening a large and small steam turbine regulating gate to reduce the amount of working steam entering a main steam turbine during load reduction.
8. The method for participating in primary frequency modulation and load change of a power grid by using a steam-electric double-drive unit according to claim 1 is characterized in that the method is suitable for a steam turbine unit and a sequence valve steam distribution unit of which a main steam turbine is full-cycle steam inlet throttling steam distribution, and can be independently used for responding to primary frequency modulation or be used together with the existing primary frequency modulation technologies.

Description

Method for participating primary frequency modulation and load change of power grid by using gas-electric double-drive unit Technical Field The invention relates to the field of automatic control of thermal generator sets, in particular to a method for participating in primary frequency modulation and load change of a power grid by a steam-electric double-drive unit. Background Under the constraints of clean energy consumption and environmental protection, higher requirements are put forward for power generation enterprises. In recent years, the technology of the gas-electric double-drive suction fan gradually starts to be popularized and applied in the power generation field due to the advantages of low station service power, high heat supply flexibility, low power supply coal consumption and the like. The back pressure type gas-electric double-drive suction fan unit comprises a back pressure type turbine, a fixed speed ratio gear box, an asynchronous motor and a fan, the back pressure type turbine is always operated in a high-efficiency area, a back pressure type turbine is in a fully-opened state after being loaded, and a primary frequency modulation function is not designed. Meanwhile, the turbo generator set in grid-connected operation is generally required to have a primary frequency modulation function. Therefore, the technical blank that the steam-electric double-drive suction fan technology does not relate to the primary frequency modulation function is filled according to the operation characteristics of the steam-electric double-drive unit, and the technical problem to be solved is solved. Disclosure of Invention The invention aims to overcome the defects of the prior art and provide a method for participating in primary frequency modulation and load change of a power grid by a steam-electric double-drive unit. The aim of the invention can be achieved by the following technical scheme: According to one aspect of the invention, a method for participating in primary frequency modulation load change of a power grid by a steam-electric double-drive unit is provided, the steam-electric double-drive unit comprises a small turbine and an asynchronous motor, when the power grid frequency is reduced to a set first threshold value, the steam inlet quantity of the small turbine is reduced by closing a regulating valve of the small turbine, the energy storage of extraction steam serving as a steam source of the small turbine is released, more steam is enabled to enter a main turbine to apply work, the primary frequency modulation load adding function is realized, and when the power grid frequency is increased to a set second threshold value, the steam inlet quantity of the small turbine is increased by opening a regulating valve of the large turbine, the power steam quantity entering the main turbine is reduced, and the primary frequency modulation load reducing function is realized. According to the method, when the power grid frequency change exceeds the set frequency difference during operation of the gas-electric double-drive unit, primary frequency modulation load requirements are calculated and determined according to the power grid frequency difference and the actual output condition of the unit. According to the method, after primary frequency modulation load requirements are determined, the direction and the amplitude of the action required by the small turbine inlet steam modulation valve are calculated by combining CCS and DEH side control strategies. As an optimized technical scheme, when the small turbine valve is regulated by the method, the coordinated control system correspondingly changes the regulated quantity of the main regulating system of the unit, including the fuel quantity, the water supply flow and the air quantity, rapidly compensates the energy requirement of the unit, provides the frequency modulation power output with the required amplitude and the duration of frequency modulation, and reduces the fluctuation of main parameters of the steam pressure and the steam temperature of the unit. As an optimal technical scheme, when the method is used for loading, the MEH of the small turbine automatically sends out a command, and the steam inlet regulating valve of the small turbine is directly and quickly closed to a preset opening degree, so that more steam enters the main turbine to apply work, thereby the output of the unit is instantaneously increased, and the primary frequency modulation loading requirement is responded. As a preferable technical scheme, the specific loading process is as follows: step 1, normally operating a small steam turbine, and determining primary frequency modulation load requirements according to power grid frequency difference and actual output conditions of a unit when power grid frequency drops to exceed a set first threshold value; Step 2, judging whether the steam turbine is within a safety boundary, if so, closing a small steam turbine valve and exec