CN114396327B - Method for adjusting power grid frequency by steam extraction of steam turbine - Google Patents

Method for adjusting power grid frequency by steam extraction of steam turbine Download PDF

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CN114396327B
CN114396327B CN202111500429.3A CN202111500429A CN114396327B CN 114396327 B CN114396327 B CN 114396327B CN 202111500429 A CN202111500429 A CN 202111500429A CN 114396327 B CN114396327 B CN 114396327B
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low
steam
pressure heater
steam inlet
pressure
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CN114396327A (en
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文立斌
胡弘
李俊
孙志媛
吴健旭
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Electric Power Research Institute of Guangxi Power Grid Co Ltd
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Electric Power Research Institute of Guangxi Power Grid Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K7/00—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
    • F01K7/34—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being of extraction or non-condensing type; Use of steam for feed-water heating
    • F01K7/345—Control or safety-means particular thereto
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D15/00—Adaptations of machines or engines for special use; Combinations of engines with devices driven thereby
    • F01D15/10—Adaptations for driving, or combinations with, electric generators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K13/00—General layout or general methods of operation of complete plants
    • F01K13/02—Controlling, e.g. stopping or starting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K7/00—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating
    • F01K7/34—Steam engine plants characterised by the use of specific types of engine; Plants or engines characterised by their use of special steam systems, cycles or processes; Control means specially adapted for such systems, cycles or processes; Use of withdrawn or exhaust steam for feed-water heating the engines being of extraction or non-condensing type; Use of steam for feed-water heating
    • F01K7/44—Use of steam for feed-water heating and another purpose
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22D—PREHEATING, OR ACCUMULATING PREHEATED, FEED-WATER FOR STEAM GENERATION; FEED-WATER SUPPLY FOR STEAM GENERATION; CONTROLLING WATER LEVEL FOR STEAM GENERATION; AUXILIARY DEVICES FOR PROMOTING WATER CIRCULATION WITHIN STEAM BOILERS
    • F22D1/00—Feed-water heaters, i.e. economisers or like preheaters
    • F22D1/50—Feed-water heaters, i.e. economisers or like preheaters incorporating thermal de-aeration of feed-water
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency

Abstract

The invention belongs to the technical fields of heat supply, power generation and control analysis thereof, and particularly relates to a method for adjusting the frequency of a power grid by extracting steam from a steam turbine. After the power grid frequency deviates from 50Hz, the opening degrees of the deaerator steam inlet regulating valve, the I low-pressure heater steam inlet regulating valve, the II low-pressure heater steam inlet regulating valve, the III low-pressure heater steam inlet regulating valve and the IV low-pressure heater steam inlet regulating valve are controlled, so that the steam flow extracted from the medium-pressure cylinder and the low-pressure cylinder is regulated, the power of the generator is further regulated, the power of the generator is changed, the power grid frequency is close to 50Hz, the steam turbine steam extraction is realized to participate in the power grid frequency regulating function, and the stability of the power grid frequency is maintained.

Description

Method for adjusting power grid frequency by steam extraction of steam turbine
Technical Field
The invention belongs to the technical fields of heat supply, power generation and control analysis thereof, and particularly relates to a method for adjusting the frequency of a power grid by extracting steam from a steam turbine.
Background
The electric monitoring bureau in each region of the country successively goes out of the rule of implementation of grid-connected operation management of the power plant and the rule of implementation of auxiliary service management of the grid-connected power plant (abbreviated as two rules) in 2008, and according to the two rules, the thermal power unit is required to have a primary frequency modulation function, and the primary frequency modulation is put into the thermal power unit after grid connection, so that the effect of the primary force of grid frequency modulation is played. At present, when the frequency of the power grid of the steam turbine generator unit is deviated from 50Hz and exceeds a dead zone, the deviation value is converted into a valve position instruction of a steam turbine valve through digital calculation, so that the corresponding action of a high-pressure valve of the steam turbine is realized to regulate the power of the unit, and a contribution is made for stabilizing the frequency of the power grid at 50 Hz. Because the power grid frequency is fluctuated and changed around 50Hz in real time, the high-pressure regulating valve of the steam turbine is frequently operated, and the main steam pressure of the boiler and the flux of the steam turbine also follow the frequent fluctuated and changed. The high-pressure regulating valve of the steam turbine controls high-temperature and high-pressure superheated steam, and frequent alternating fluctuation changes of the high-pressure regulating valve can not only cause fatigue damage risks of equipment such as a boiler, the high-pressure regulating valve and a steam turbine body, but also reduce the running efficiency of unit equipment. In order to solve the technical problems of the steam turbine generator unit participating in the frequency modulation adjustment process of the power grid, the invention provides a method for adjusting the frequency of the power grid by extracting steam from a steam turbine.
Disclosure of Invention
In order to solve the problems, the invention provides a method for adjusting the frequency of a power grid by extracting steam from a steam turbine, which comprises the following specific technical scheme:
a method for adjusting the frequency of a power grid by extracting steam from a steam turbine, wherein the steam turbine comprises a medium pressure cylinder, a low pressure cylinder, a deaerator and a low pressure heater; the medium pressure cylinder is connected with the low pressure cylinder, and the low pressure cylinder is connected with the generator rotor; the method comprises the following steps:
s1: connecting a middle pressure cylinder steam outlet of a middle pressure cylinder with a deaerator through a deaerator steam inlet pipe; the method comprises the steps that a steam extraction port of a low-pressure cylinder is connected with the steam side of a low-pressure heater through a low-pressure heater steam inlet pipe, a deaerator steam inlet regulating valve is arranged on the deaerator steam inlet pipe, and a low-pressure heater steam inlet regulating valve is arranged on the low-pressure heater steam inlet pipe, wherein the steam extraction port of the low-pressure cylinder is connected with the low-pressure heater;
s2: collecting voltage and current output by a generator rotor in real time, and obtaining output power and frequency of the generator rotor through collected voltage signals and current signals;
s3: and calculating according to the frequency and the output power of the generator rotor to obtain valve opening control instructions of the deaerator steam inlet regulating valve and the low-pressure heater steam inlet regulating valve, and controlling the opening of the deaerator steam inlet regulating valve and the low-pressure heater steam inlet regulating valve according to the obtained valve opening control instructions so as to regulate the output power and the frequency of the generator rotor.
Preferably, the low-pressure heaters are arranged in a plurality, the number of the steam extraction ports of the low-pressure cylinders is consistent with that of the low-pressure heaters, and the steam extraction ports of each low-pressure cylinder are respectively connected with the steam side of the corresponding low-pressure heater through the steam inlet pipe of the low-pressure heater; and each low-pressure heater steam inlet pipe is provided with a corresponding low-pressure heater steam inlet regulating valve for regulating the steam quantity flowing through each low-pressure heater steam inlet pipe.
Preferably, 4 low-pressure heaters are arranged, namely, a first low-pressure heater, a second low-pressure heater, a third low-pressure heater and a fourth low-pressure heater;
the low pressure cylinder is respectively provided with an IV low pressure cylinder steam extraction port, a III low pressure cylinder steam extraction port, an II low pressure cylinder steam extraction port and an I low pressure cylinder steam extraction port;
the steam extraction port of the first low-pressure cylinder is connected with the first low-pressure heater through a steam inlet pipe of the first low-pressure heater, and a steam inlet regulating valve of the first low-pressure heater electrically connected with the data acquisition and control device is arranged on the steam inlet pipe of the first low-pressure heater; the steam inlet pipe of the first low-pressure heater is used for extracting steam from the steam extraction port of the first low-pressure cylinder and flowing the steam into the first low-pressure heater;
the steam extraction port of the second low-pressure cylinder is connected with the second low-pressure heater through a steam inlet pipe of the second low-pressure heater, and a steam inlet regulating valve of the second low-pressure heater electrically connected with the data acquisition and control device is arranged on the steam inlet pipe of the second low-pressure heater; the second low-pressure heater steam inlet pipe is used for extracting steam from a second low-pressure cylinder steam extraction port and flowing the steam into the second low-pressure heater;
the third low-pressure cylinder steam extraction port is connected with the third low-pressure heater through a third low-pressure heater steam inlet pipe, and a third low-pressure heater steam inlet regulating valve electrically connected with the data acquisition and control device is arranged on the third low-pressure heater steam inlet pipe; the third low-pressure heater steam inlet pipe is used for extracting steam from a third low-pressure cylinder steam extraction port and flowing the steam into the third low-pressure heater;
the fourth low-pressure cylinder steam extraction port is connected with a fourth low-pressure heater through a fourth low-pressure heater steam inlet pipe, and a fourth low-pressure heater steam inlet regulating valve which is electrically connected with the data acquisition and control device is arranged on the fourth low-pressure heater steam inlet pipe; and the steam inlet pipe of the IV low-pressure heater is used for extracting steam from the steam extraction port of the IV low-pressure cylinder and flowing the steam into the IV low-pressure heater.
Preferably, the step S3 specifically includes the following steps:
s31: the acquired output frequency f of the generator rotor is differed from the power grid frequency of 50Hz to obtain a frequency difference value delta f;
s32: passing the frequency difference Δf through a power conversion coefficient K 0 Is converted into a power command and is matched with the current power command P of the steam turbine unit s Difference is made to obtain new power order P N ；
S33: new power command P N Divided into two paths of signals, the first path of new power makes P N Controlled feedforward coefficient K 1 Converting into a power command signal;
s34: the power command signal passes through the flow conversion coefficient K cq Converting into a flow instruction signal, and controlling the opening of a deaerator steam inlet regulating valve and the opening of a low-pressure heater steam inlet regulating valve;
s35: after the deaerator steam inlet regulating valve and the low-pressure heater steam inlet regulating valve act, the new power of the second path is led to be P N With the generator rotor power real-time value P E Comparing, the deviation is input into PID link, and the PID link outputs new power command P with the first path N Controlled feedforward coefficient K 1 The converted signals are summed to form a new P V Instructions, converted into flow instruction signals C V Flow instruction signal C V Simultaneously distributing the deaerator steam inlet regulating valve and the low-pressure heater steam inlet regulating valve;
s36: the deaerator steam inlet regulating valve and the low-pressure heater steam inlet regulating valve act again until the new power makes P N With the generator rotor power real-time value P E The deviation is zero;
s37: steps S32-S36 are repeated when a new signal frequency difference value af occurs.
Preferably, Δf=f-50 in step S31.
Preferably, the step S32 further includes converting the frequency difference Δf into a power command after the frequency difference Δf exceeds the dead zone ±Δe.
Preferably, the power conversion system in the step S32Number K 0 The calculation is as follows:
K 0 =rated power/2.5.
Preferably, the flow conversion coefficient K in the step S34 cq The calculation mode of (2) is as follows:
K cq ＝1/P cq ；
Figure BDA0003401379110000041
wherein eta 0 The power influence coefficient is the power influence coefficient of the change of the steam intake and extraction quantity of the deaerator; η (eta) 1 The power influence coefficient is the power influence coefficient of the steam inlet and steam extraction quantity change of the first low-pressure heater; η (eta) 2 The power influence coefficient is the change of the steam inlet and steam extraction quantity of the second low-pressure heater; η (eta) 3 The power influence coefficient is changed for the steam inlet and steam extraction quantity of the third low-pressure heater; η (eta) 4 The power influence coefficient is the change of the steam inlet and steam extraction quantity of the IV low-pressure heater; q (Q) 0 The steam inlet and extraction amount of the deaerator; q (Q) 1 The steam inlet and extraction quantity of the first low-pressure heater is; q (Q) 2 The steam inlet and extraction quantity of the second low-pressure heater is set; q (Q) 3 The steam inlet and extraction quantity of the third low-pressure heater is set; q (Q) 4 And (5) the steam inlet and extraction quantity of the fourth low-pressure heater is obtained.
Preferably, the flow instruction signal C in the step S35 V Meanwhile, the air inlet regulating valve of the deaerator and the air inlet regulating valve of the low-pressure heater are specifically:
according to the flow command signal C V Obtaining opening signals f corresponding to the deaerator steam inlet regulating valve, the I low-pressure heater steam inlet regulating valve, the II low-pressure heater steam inlet regulating valve, the III low-pressure heater steam inlet regulating valve and the IV low-pressure heater steam inlet regulating valve 0 (C V )、f 1 (C V )、f 2 (C V )、f 3 (C V )、f 4 (C V ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein the control curve y of the deaerator steam inlet regulating valve 0 ＝f 0 (x) The method comprises the steps of carrying out a first treatment on the surface of the I low-pressure heater steam inlet regulating valve control curve y 1 ＝f 1 (x) The method comprises the steps of carrying out a first treatment on the surface of the II low pressure heater admission regulator valve control curve y 2 ＝f 2 (x) The method comprises the steps of carrying out a first treatment on the surface of the III control curve y of steam inlet regulating valve of low-pressure heater 3 ＝f 3 (x) The method comprises the steps of carrying out a first treatment on the surface of the IV low-pressure heater steam inlet regulating valve control curve y 4 ＝f 4 (x)。
The beneficial effects of the invention are as follows: after the power grid frequency deviates from 50Hz, the opening degrees of the deaerator steam inlet regulating valve, the I low-pressure heater steam inlet regulating valve, the II low-pressure heater steam inlet regulating valve, the III low-pressure heater steam inlet regulating valve and the IV low-pressure heater steam inlet regulating valve are controlled, so that the steam flow extracted from the medium-pressure cylinder and the low-pressure cylinder is regulated, the power of the generator is further regulated, the power of the generator is changed, the power grid frequency is close to 50Hz, the steam turbine steam extraction is realized to participate in the power grid frequency regulating function, and the stability of the power grid frequency is maintained.
The invention can enhance the participation of the thermal power unit in the primary frequency modulation function of the power grid, solve the hidden trouble of fatigue damage accidents of equipment such as boilers, high-pressure regulating gates, turbine bodies and the like caused by frequent actions of the high-pressure regulating gates of the turbine caused by the traditional primary frequency modulation mode, and prevent the problem of reduction of the inter-stage efficiency of movable blades of the turbine caused by frequent alternating and submerged fluctuation changes of high-temperature and high-pressure superheated steam controlled by the high-pressure regulating gates of the turbine.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Like elements or portions are generally identified by like reference numerals throughout the several figures. In the drawings, elements or portions thereof are not necessarily drawn to scale.
FIG. 1 is a schematic flow chart of the present invention;
FIG. 2 is a control logic diagram of the present invention;
FIG. 3 is a schematic diagram of a system architecture to which the present invention is applied;
wherein, among them, the deaerator steam inlet check valve 1, the deaerator steam inlet stop valve 2, the deaerator steam inlet regulating valve 3, the deaerator steam inlet pipe 4, the deaerator 5, the water supply pump inlet pipe 6, the water supply pump 7, the water supply pump outlet check valve 8, the water supply pump outlet pipe 9, the deaerator condensate water inlet main pipe 10, the I low-pressure heater steam inlet check valve 11, the I low-pressure heater steam inlet stop valve 12, the I low-pressure heater steam inlet regulating valve 13, the I low-pressure heater steam inlet pipe 14, the I low-pressure heater 15, the I low-pressure heater drain pipe 16, the I-II low-pressure heater condensate water main pipe 17, the condenser 18, the II low-pressure heater steam inlet stop valve 19, the II low-pressure heater steam inlet stop valve 20, the II low-pressure heater steam inlet regulating valve 21, the II low-pressure heater steam inlet pipe 22, the II low-pressure heater 23, the II low-pressure heater drain pipe 24 the condensate main pipe 25 between the low-pressure heaters II-III, the check valve 26 of the low-pressure heater III, the steam stop valve 27 of the low-pressure heater III, the steam inlet regulating valve 28 of the low-pressure heater III, the steam inlet pipe 29 of the low-pressure heater III, the condensate main pipe 30 of the low-pressure heater III, the drain pipe 31 of the low-pressure heater III, the condensate main pipe 32 between the low-pressure heaters III, the steam stop valve 33 of the low-pressure heater IV, the steam stop valve 34 of the low-pressure heater IV, the steam inlet regulating valve 35 of the low-pressure heater IV, the steam inlet pipe 36 of the low-pressure heater IV, the drain pipe 38 of the low-pressure heater IV, the condensate main pipe 39 of the low-pressure heater IV, the condensate inlet pipe 40 of the condensate pump 41, the outlet check valve 42 of the condensate outlet pipe 43 of the condensate pump, the seal heater 44, the water level regulating valve 45 of the deaerator, generator stator 46, voltage converter 47, three-phase power parameter tester 48, current converter 49, generator rotor 50, low pressure cylinder 51, iv low pressure cylinder steam extraction port 52, iii low pressure cylinder steam extraction port 53, ii low pressure cylinder steam extraction port 54, i low pressure cylinder steam extraction port 55, middle low pressure cylinder communication pipe 56, middle pressure cylinder steam exhaust port 57, middle pressure cylinder 58, middle pressure regulator 59, high pressure regulator 60, high pressure cylinder 61, high pressure cylinder steam exhaust check valve 62, reheat main steam pipe 63, main steam pipe 64, high pressure cylinder steam exhaust pipe 65, boiler 66, water supply main pipe 67, high pressure heater system 68, and data acquisition and control module 69.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be understood that the terms "comprises" and "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
As shown in fig. 1, the embodiment of the invention provides a method for adjusting the frequency of a power grid by extracting steam from a steam turbine, wherein the steam turbine comprises a medium pressure cylinder 58, a low pressure cylinder 51, a deaerator 5 and a low pressure heater; the intermediate pressure cylinder 58 is connected with the low pressure cylinder 51, and the low pressure cylinder 51 is connected with the generator rotor 50; the method comprises the following steps:
s1: the middle pressure cylinder exhaust port 57 of the middle pressure cylinder 58 is connected with the deaerator 5 through the deaerator steam inlet pipe 4; the steam extraction port of the low-pressure cylinder 51 is connected with the steam side of the low-pressure heater through a low-pressure heater steam inlet pipe, a deaerator steam inlet regulating valve 3 is arranged on the deaerator steam inlet pipe 4, and a low-pressure heater steam inlet regulating valve is arranged on the low-pressure heater steam inlet pipe, the steam extraction port of the low-pressure cylinder 51 is connected with the low-pressure heater;
s2: collecting the voltage and the current output by the generator rotor 50 in real time, and obtaining the output power and the frequency of the generator rotor 50 through the collected voltage signals and the collected current signals;
s3: and calculating according to the frequency and the output power of the generator rotor 50 to obtain valve opening control instructions of the deaerator steam inlet regulating valve 3 and the low-pressure heater steam inlet regulating valve, and controlling the opening of the deaerator steam inlet regulating valve 3 and the low-pressure heater steam inlet regulating valve according to the obtained valve opening control instructions, so as to regulate the output power and the frequency of the generator rotor 50.
The number of the low-pressure heaters is equal to the number of the low-pressure heaters, and the steam extraction ports of each low-pressure cylinder 51 are respectively connected with the steam sides of the corresponding low-pressure heaters through low-pressure heater steam inlet pipes; and each low-pressure heater steam inlet pipe is provided with a corresponding low-pressure heater steam inlet regulating valve for regulating the steam quantity flowing through each low-pressure heater steam inlet pipe.
In the present embodiment, 4 low-pressure heaters are provided, i.e., the first low-pressure heater 15, ii low-pressure heater 23, iii low-pressure heater 30, iv low-pressure heater 37;
the low pressure cylinder 51 is provided with an IV low pressure cylinder steam extraction port 52, an III low pressure cylinder steam extraction port 53, an II low pressure cylinder steam extraction port 54 and an I low pressure cylinder steam extraction port 55 respectively;
the first low-pressure cylinder steam extraction port 55 is connected with the first low-pressure heater 15 through a first low-pressure heater steam inlet pipe 14, and the first low-pressure heater steam inlet pipe 14 is provided with a first low-pressure heater steam inlet regulating valve 13 electrically connected with a data acquisition and control device 69; the I low-pressure heater steam inlet pipe 14 is used for extracting steam from the I low-pressure cylinder steam extraction port 55 and flowing the steam into the I low-pressure heater 15;
the second low-pressure cylinder steam extraction port 54 is connected with the second low-pressure heater 23 through a second low-pressure heater steam inlet pipe 22, and a second low-pressure heater steam inlet regulating valve 21 electrically connected with a data acquisition and control device 69 is arranged on the second low-pressure heater steam inlet pipe 22; the second low-pressure heater steam inlet pipe 22 is used for extracting steam from the second low-pressure cylinder steam extraction port 54 and flowing the steam into the second low-pressure heater 23;
the third low-pressure cylinder steam extraction port 53 is connected with the third low-pressure heater 30 through a third low-pressure heater steam inlet pipe 29, and a third low-pressure heater steam inlet regulating valve 28 electrically connected with a data acquisition and control device 69 is arranged on the third low-pressure heater steam inlet pipe 29; the third low-pressure heater steam inlet pipe 29 is used for extracting steam from the third low-pressure cylinder steam extraction port 53 and flowing the steam into the third low-pressure heater 30;
the fourth low-pressure cylinder steam extraction port 52 is connected with a fourth low-pressure heater 37 through a fourth low-pressure heater steam inlet pipe 36, and a fourth low-pressure heater steam inlet regulating valve 35 electrically connected with a data acquisition and control device 69 is arranged on the fourth low-pressure heater steam inlet pipe 36; the fourth low pressure heater inlet 36 is configured to draw steam from the fourth low pressure cylinder bleed 52 into the fourth low pressure heater 37.
As shown in fig. 2, the step S3 specifically includes the following steps:
s31: the acquired output frequency f of the generator rotor 50 is differed from the power grid frequency 50Hz to obtain a frequency difference value delta f; Δf=f-50.
S32: after the frequency difference Δf exceeds the dead zone ±Δe, the frequency difference Δf is converted into a power command. The method comprises the following steps: passing the frequency difference Δf through a power conversion coefficient K 0 Is converted into a power command and is matched with the current power command P of the steam turbine unit s Difference is made to obtain new power order P N ；K 0 The calculation is as follows:
K 0 =rated power/2.5.
S33: new power command P N Divided into two paths of signals, the first path of new power makes P N Controlled feedforward coefficient K 1 Converting into a power command signal;
s34: the power command signal passes through the flow conversion coefficient K cq Converting into a flow instruction signal and controlling the opening of the deaerator steam inlet regulating valve 3 and the opening of the low-pressure heater steam inlet regulating valve; k (K) cq The calculation mode of (2) is as follows: k (K) cq ＝1/P cq ；
Figure BDA0003401379110000091
Wherein eta 0 The power influence coefficient is caused by the change of the steam intake and extraction quantity of the deaerator 5; η (eta) 1 The power influence coefficient is changed for the steam intake and extraction quantity of the first low-pressure heater 15; η (eta) 2 The power influence coefficient is changed for the steam intake and extraction quantity of the II low-pressure heater 23; η (eta) 3 The power influence coefficient is changed for the steam intake and extraction quantity of the third low-pressure heater 30; η (eta) 4 The power influence coefficient is changed for the steam intake and extraction quantity of the IV low-pressure heater 37; q (Q) 0 The steam inlet and extraction amount of the deaerator 5 is set; q (Q) 1 The steam inlet and extraction quantity of the first low-pressure heater 15 is set; q (Q) 2 The steam inlet and extraction amount of the second low-pressure heater 23 is set; q (Q) 3 The steam inlet and extraction amount of the third low-pressure heater 30 is set; q (Q) 4 And the steam inlet and extraction quantity of the fourth low-pressure heater 37 is obtained.
S35: after the deaerator steam inlet regulating valve 3 and the low-pressure heater steam inlet regulating valve act, a second new power is led to be P N With the generator rotor 50 power real time value P E Comparing, the deviation is input into PID link, and the PID link outputs new power command P with the first path N Controlled feedforward coefficient K 1 The converted signals are summed to form a new P V Instructions, converted into flow instruction signals C V Flow instruction signal C V Simultaneously distributing the deaerator steam inlet regulating valve 3 and the low-pressure heater steam inlet regulating valve; flow instruction signal C V The air inlet regulating valve 3 of the deaerator and the air inlet regulating valve of the low-pressure heater are distributed at the same time, and the air inlet regulating valve is specifically as follows:
according to the flow command signal C V Obtaining opening signals f corresponding to the deaerator steam inlet regulating valve 3, the I low-pressure heater steam inlet regulating valve 13, the II low-pressure heater steam inlet regulating valve 21, the III low-pressure heater steam inlet regulating valve 28 and the IV low-pressure heater steam inlet regulating valve 35 0 (C V )、f 1 (C V )、f 2 (C V )、f 3 (C V )、f 4 (C V ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein the deaerator steam inlet regulating valve 3 controls curve y 0 ＝f 0 (x) The method comprises the steps of carrying out a first treatment on the surface of the Control curve y of steam inlet regulating valve 13 of first low-pressure heater 1 ＝f 1 (x) The method comprises the steps of carrying out a first treatment on the surface of the II low pressure heater admission regulationValve 21 control curve y 2 ＝f 2 (x) The method comprises the steps of carrying out a first treatment on the surface of the III control curve y of low-pressure heater admission regulating valve 28 3 ＝f 3 (x) The method comprises the steps of carrying out a first treatment on the surface of the IV low-pressure heater steam inlet regulating valve 35 control curve y 4 ＝f 4 (x)。
S36: the deaerator steam inlet regulating valve 3 and the low-pressure heater steam inlet regulating valve act again until the new power makes P N With the generator rotor 50 power real time value P E The deviation is zero;
s37: steps S32-S36 are repeated when a new signal frequency difference value af occurs.
As shown in fig. 3, a system for the application of the present invention is provided, which comprises a boiler 66, a high pressure cylinder 61, a medium pressure cylinder 58, a low pressure cylinder 51, a deaerator 5, a first low pressure heater 15, a second low pressure heater 23, a third low pressure heater 30, a fourth low pressure heater 37, and a condenser 18; the high-pressure cylinder 61 is connected with a boiler 66 through a high-pressure cylinder exhaust check valve 62 and a high-pressure cylinder exhaust pipe 65; the boiler 66 is connected with the high-pressure cylinder 61 through a main steam pipe 64; the main steam pipe 64 is provided with a high-pressure regulating valve 60; the boiler 66 is connected with the medium pressure cylinder 58 through a reheating main steam pipe 63, and a medium pressure regulating valve 59 is arranged on the reheating main steam pipe 63; the high pressure cylinder 61, the middle pressure cylinder 58 and the low pressure cylinder 51 are connected in sequence; the low pressure cylinder 51 is connected with the generator rotor 50; the low-pressure cylinder 51 is connected with the condenser 18; the first low-pressure heater 15, the second low-pressure heater 23, the third low-pressure heater 30 and the fourth low-pressure heater 37 are connected in sequence; the intermediate pressure cylinder 58 is connected to the low pressure cylinder 51 through the intermediate pressure cylinder communication pipe 56.
The middle pressure cylinder 58 is provided with a middle pressure cylinder steam exhaust port 57; the low pressure cylinder 51 is respectively provided with an IV low pressure cylinder steam extraction port 52, an III low pressure cylinder steam extraction port 53, an II low pressure cylinder steam extraction port 54 and an I low pressure cylinder steam extraction port 55; the pressure levels of different steam extraction ports are different, and steam of each steam extraction port is from a symmetrical cavity with the same pressure level of the low pressure cylinder.
The medium-pressure cylinder steam exhaust port 57 is communicated with the deaerator 5 through a deaerator steam inlet pipe 4; a deaerator steam inlet regulating valve 3 is arranged on the deaerator steam inlet pipe 4;
the first low-pressure cylinder steam extraction port 55 is connected with the steam side of the first low-pressure heater 15 through a first low-pressure heater steam inlet pipe 14, and the first low-pressure heater steam inlet pipe 14 is provided with a first low-pressure heater steam inlet regulating valve 13 electrically connected with a data acquisition and control device 69; the I low-pressure heater steam inlet pipe 14 is used for extracting steam from the I low-pressure cylinder steam extraction port 55 and flowing the steam into the I low-pressure heater 15;
the second low-pressure cylinder steam extraction port 54 is connected with the steam side of the second low-pressure heater 23 through a second low-pressure heater steam inlet pipe 22, and the second low-pressure heater steam inlet pipe 22 is provided with a second low-pressure heater steam inlet regulating valve 21 electrically connected with a data acquisition and control device 69; the second low-pressure heater steam inlet pipe 22 is used for extracting steam from the second low-pressure cylinder steam extraction port 54 and flowing the steam into the second low-pressure heater 23;
the third low pressure cylinder steam extraction port 53 is connected with the steam side of the third low pressure heater 30 through a third low pressure heater steam inlet pipe 29, and a third low pressure heater steam inlet regulating valve 28 electrically connected with a data acquisition and control device 69 is arranged on the third low pressure heater steam inlet pipe 29; the third low-pressure heater steam inlet pipe 29 is used for extracting steam from the third low-pressure cylinder steam extraction port 53 and flowing the steam into the third low-pressure heater 30;
the fourth low-pressure cylinder steam extraction port 52 is connected with the steam side of the fourth low-pressure heater 37 through a fourth low-pressure heater steam inlet pipe 36, and a fourth low-pressure heater steam inlet regulating valve 35 electrically connected with a data acquisition and control device 69 is arranged on the fourth low-pressure heater steam inlet pipe 36; the fourth low-pressure heater steam inlet pipe 36 is used for extracting steam from the fourth low-pressure cylinder steam extraction port 52 and flowing the steam into the fourth low-pressure heater 37;
the system also comprises a data acquisition and control device 69, a three-phase power parameter tester 48, a current converter 49 and a voltage converter 47; the current converter 49 and the voltage converter 47 are respectively connected with the generator rotor 50, and are respectively used for collecting the output current and the output voltage of the generator rotor 50, respectively converting the collected current and the collected voltage, and inputting the converted current and the collected voltage into the three-phase power parameter tester 48; the three-phase power parameter tester 48 is respectively connected with the current converter 49, the voltage converter 47 and the data acquisition and control device 69, and is used for calculating the current and the voltage converted by the current converter 49 and the voltage converter 47 and outputting power and frequency signals to the data acquisition and control device 69 according to the calculation result; the data acquisition and control device 69 is used for controlling the opening degrees of the deaerator steam inlet regulating valve 3, the I low-pressure heater steam inlet regulating valve 13, the II low-pressure heater steam inlet regulating valve 21, the III low-pressure heater steam inlet regulating valve 28 and the IV low-pressure heater steam inlet regulating valve 35 according to the power and frequency signals output by the three-phase power parameter tester 48.
Wherein, the condenser 18 is connected with the shaft seal heater 44 through the condensate pump water inlet main pipe 40; the shaft seal heater 44 is connected with the IV low-pressure heater 37 through an IV low-pressure heater water inlet condensate header 39; the fourth low-pressure heater 37 is connected with the third low-pressure heater 30 through a condensate header 32 among the III-IV low-pressure heaters; the third low-pressure heater 30 is connected with the second low-pressure heater 23 through a condensation water mother pipe 25 among the second low-pressure heaters; the second low-pressure heater 23 is connected with the first low-pressure heater 15 through a condensation water mother pipe 17 between the first low-pressure heater and the second low-pressure heater; the first low-pressure heater 15 is connected with the deaerator 5 through a condensate pipe 10 for entering the deaerator; the deaerator water level regulating valve 45 is arranged on the water inlet condensation water mother pipe 39 of the IV low-pressure heater, and the deaerator water level regulating valve 45 is used for regulating the water level of the deaerator 5; the condensate in the condenser 18 sequentially passes through the shaft seal heater 44, the IV low-pressure heater 37, the III low-pressure heater 30, the II low-pressure heater 23 and the I low-pressure heater 15, and finally the condensate flowing into the I low-pressure heater 15 enters the deaerator 5 through the deaerator condensate main pipe 10.
A condensate pump 41 and a condensate pump outlet check valve 42 are sequentially connected to a condensate pump water inlet main pipe 40 connected with a shaft seal heater 44 by the condenser 18; the condensate pump 41 is used for pumping up the condensate in the condenser 18 and then sending the condensate to the shaft seal heater 44.
Wherein the first low-pressure heater 15 is connected with the second low-pressure heater 23 through the first low-pressure heater drain pipe 16; the second low-pressure heater 23 is connected with the third low-pressure heater 30 through a second low-pressure heater drain pipe 24; the third low-pressure heater 30 is connected with the IV low-pressure heater 37 through a third low-pressure heater drain pipe 31; the fourth low-pressure heater 37 is connected with the condenser 18 through a drain pipe 38 of the fourth low-pressure heater;
steam in the steam inlet pipe 14 of the first low-pressure heater flows into the first low-pressure heater 15, condensed water is condensed to form drain water, and the drain water flows into the second low-pressure heater 23 through the drain pipe 16 of the first low-pressure heater;
steam in the steam inlet pipe 22 of the second low-pressure heater enters the second low-pressure heater 23, condensed water is condensed to form drain water, and the drain water flows into the third low-pressure heater 30 through the drain pipe 24 of the second low-pressure heater;
steam in the III low-pressure heater steam inlet pipe 29 enters the III low-pressure heater 30, condensed water is condensed to form drain water, and the drain water flows into the IV low-pressure heater 30 through the III low-pressure heater drain pipe 31;
steam in the steam inlet pipe 36 of the fourth low-pressure heater enters the fourth low-pressure heater 37, condensed water is condensed to form drain water, and the drain water flows into the condenser 18 through the drain pipe 38 of the fourth low-pressure heater.
The deaerator 5 is connected with a feed pump 7 through a feed pump inlet pipe 6; the feed pump 7 is connected with a high-pressure heater system 68 through a feed pump outlet check valve 8 and a feed pump outlet pipe 9 in sequence, and the high-pressure heater system 68 is connected with a boiler 66 through a feed water main pipe 67.
The I low-pressure heater steam inlet pipe 14 is sequentially provided with an I low-pressure heater steam inlet check valve 11, an I low-pressure heater steam inlet stop valve 12 and an I low-pressure heater steam inlet regulating valve 13 from an I low-pressure cylinder steam extraction port 55 to an I low-pressure heater 15;
a second low-pressure heater steam inlet check valve 19, a second low-pressure heater steam inlet stop valve 20 and a second low-pressure heater steam inlet regulating valve 21 are sequentially arranged on the second low-pressure heater steam inlet pipe 22 from the second low-pressure cylinder steam extraction port 54 to the second low-pressure heater 23;
a third low-pressure heater steam inlet check valve 26, a third low-pressure heater steam inlet stop valve 27 and a third low-pressure heater steam inlet regulating valve 28 are sequentially arranged on the third low-pressure heater steam inlet pipe 29 from the third low-pressure cylinder steam extraction port 53 to the third low-pressure heater 30;
the fourth low-pressure heater steam inlet pipe 36 is provided with a fourth low-pressure heater steam inlet check valve 33, a fourth low-pressure heater steam inlet stop valve 34 and a fourth low-pressure heater steam inlet regulating valve 35 in sequence from the fourth low-pressure cylinder steam extraction port 52 to the fourth low-pressure heater 37.
The deaerator steam inlet pipe 4 is sequentially provided with a deaerator steam inlet check valve 1, a deaerator steam inlet stop valve 2 and a deaerator steam inlet regulating valve 3 from a medium pressure cylinder steam outlet 57 to a deaerator 5.
In the embodiment, the deaerator steam inlet check valve 1, the feed pump outlet check valve 8, the I low-pressure heater steam inlet check valve 11, the II low-pressure heater steam inlet check valve 19, the III low-pressure heater steam inlet check valve 26, the IV low-pressure heater steam inlet check valve 33 and the condensate pump outlet check valve 42 adopt pneumatic butterfly valves. The data acquisition and control module 69 adopts an OVATION distributed control system; the deaerator steam inlet regulating valve 3, the I low-pressure heater steam inlet regulating valve 13, the II low-pressure heater steam inlet regulating valve 21, the III low-pressure heater steam inlet regulating valve 28 and the IV low-pressure heater steam inlet regulating valve 35 adopt hydraulic regulating valves or pneumatic regulating valves. The deaerator water level regulating valve 45 adopts an electric regulating valve or a pneumatic regulating valve, and the deaerator steam inlet stop valve 2 adopts a corrugated pipe stop valve.
In order to better understand the invention, the following is a further explanation taking 600MW pure condensation modified extraction heat supply unit as a case, the main design parameters of the steam turbine are shown in table 1, and the influence coefficient of the change of the extraction quantity of the THA working condition on the power is shown in table 2.
Table 1 main design parameters of steam turbine
Figure BDA0003401379110000151
TABLE 2 coefficient of influence of variation of steam extraction quantity on power under THA working condition
Figure BDA0003401379110000152
The control logic diagram of the data acquisition and control module 69 is shown in fig. 2, and in fig. 2: f is a power grid frequency signal, and is tested in real time by a three-phase power parameter tester 46, and the unit is Hz; Δf is a signal frequency difference value, the unit is Hz, and is determined by the formula (1); k (K) 0 Converting the delta f signal frequency difference value into a conversion coefficient of a power instruction; p (P) s The unit MW is the current power instruction of the unit; k (K) 1 For controlling the feedforward coefficient, taking 1-3; p (P) V Is a power command signal, unit MW, C V Is a flow instruction signal, and is 1/MW unit; k (K) cq Is to convert the power command signal into P V For flow command signal C V ；f 0 (C V )、f 1 (C V )、f 2 (C V )、f 3 (C V )、f 4 (C V ) Respectively a flow distribution control curve, ensuring that the flow instruction and the extraction flow of the regulating valve have linear relations, and respectively controlling the opening degrees of the deaerator steam inlet regulating valve 3, the I low-pressure heater steam inlet regulating valve 13, the II low-pressure heater steam inlet regulating valve 21, the III low-pressure heater steam inlet regulating valve 28 and the IV low-pressure heater steam inlet regulating valve 35; p (P) E For the generator power real-time value, the three-phase power parameter tester 46 tests the generator power real-time value in real time; the filtering line block module is a PID control model, K p Is a proportionality coefficient, K D Is the differential coefficient, K I Is an integral coefficient.
Δf is calculated by the grid frequency signal f tested by the three-phase power parameter tester (46) and 50Hz, and is obtained by the following steps:
Δf＝f-50； (1)
K 0 the conversion coefficient for converting the Δf signal frequency difference value into the power command is calculated by the formula (2):
K 0 =rated power/2.5=600/2.5=240; (2)
K cq Calculated from formula (3):
K cq ＝1/P cq ； (3)
in formula 3:
Figure BDA0003401379110000161
the examples are calculated according to Table 2:
P cq ＝45065(kW)＝45.065(MW)；
K cq ＝1/P cq ＝1/45.065＝0.022(1/MW)；
regulating valve instruction x is x epsilon 30, 100]Taking a system data in the range of (1), and obtaining the y corresponding to each x by the method 0 、y 1 、y 2 、y 3 、y 4 Thereby obtaining:
control curve y of deaerator steam inlet regulating valve 3 0 ＝f 0 (x)；
Control curve y of steam inlet regulating valve 13 of first low-pressure heater 1 ＝f 1 (x)；
Control curve y of steam inlet regulating valve 21 of II low-pressure heater 2 ＝f 2 (x)；
III control curve y of low-pressure heater admission regulating valve 28 3 ＝f 3 (x)；
IV low-pressure heater steam inlet regulating valve 35 control curve y 4 ＝f 4 (x)。
The discrete data form of the control curve is shown in table 3.
TABLE 3 control Curve data
x y 0 ＝f 0 (x) y 1 ＝f 1 (x) y 2 ＝f 2 (x) y 3 ＝f 3 (x) y 4 ＝f 4 (x)
30 25.5 26.3 27.9 27.8 28.2
40 42.1 41.6 41.6 41.9 40.5
50 56.6 53.2 52.2 52.6 50.2
80 85.1 81.4 81.1 81 80.7
90 93.2 91.5 90.5 90.5 90.8
95 97.7 96.7 95.7 96.1 95.9
100 100 100 100 100 100
According to the control logic diagram 2, the three-phase power parameter tester 46 calculates the power grid frequency signal f and 50Hz, which are tested in real time, to obtain a signal frequency difference value Δf, where Δf exceeds the dead zone ±Δe, in this case Δe=0.033 Hz, and Δf passes through the conversion coefficient K 0 Converting the delta f signal frequency difference value into a power instruction, and converting the current power instruction P of the unit s Subtracting the power command forms a new power command P N The first new power makes P N Immediate controlled feedforward coefficient K 1 Conversion to P V Through K cq Is to convert the power command signal into P V For flow command signal C V Flow instruction signal C V Simultaneously to each flow distribution control curve f 0 (C V )、f 1 (C V )、f 2 (C V )、f 3 (C V )、f 4 (C V ) The deaerator steam inlet regulating valve 3, the I low-pressure heater steam inlet regulating valve 13, the II low-pressure heater steam inlet regulating valve 21, the III low-pressure heater steam inlet regulating valve 28 and the IV low-pressure heater steam inlet regulating valve 35 are respectively operated.
Oxygen scavengingAfter the steam inlet regulating valve 3, the steam inlet regulating valve 13 of the first low-pressure heater, the steam inlet regulating valve 21 of the second low-pressure heater, the steam inlet regulating valve 28 of the third low-pressure heater and the steam inlet regulating valve 35 of the fourth low-pressure heater act, the new power of the first path enables P N And generator power real-time value P E Comparing the deviation with P, and inputting the deviation to PID element, and outputting the PID element to P N The first path is controlled by a feedforward coefficient K 1 The converted signals are found to form new P V Instructions through K cq Is to convert the power command signal into P V For flow command signal C V Flow instruction signal C V Simultaneously to each flow distribution control curve f 0 (C V )、f 1 (C V )、f 2 (C V )、f 3 (C V )、f 4 (C V ) The deaerator steam inlet regulating valve 3, the I low-pressure heater steam inlet regulating valve 13, the II low-pressure heater steam inlet regulating valve 21, the III low-pressure heater steam inlet regulating valve 28 and the IV low-pressure heater steam inlet regulating valve 35 are respectively operated again until the power of the generator is real-time value P E And P N The deviation is zero. The operation is repeated again when a new signal frequency difference value deltaf occurs.
Those of ordinary skill in the art will appreciate that the elements of the examples described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the elements of the examples have been described generally in terms of functionality in the foregoing description to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in this application, it should be understood that the division of units is merely a logic function division, and there may be other manners of division in practical implementation, for example, multiple units may be combined into one unit, one unit may be split into multiple units, or some features may be omitted.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention, and are intended to be included within the scope of the appended claims and description.

Claims (8)

1. A method for adjusting the frequency of a power grid by extracting steam from a steam turbine, wherein the steam turbine comprises a medium-pressure cylinder (58), a low-pressure cylinder (51), a deaerator (5) and a low-pressure heater; the medium pressure cylinder (58) is connected with the low pressure cylinder (51), and the low pressure cylinder (51) is connected with the generator rotor (50); the method is characterized in that: the method comprises the following steps:
s1: a middle pressure cylinder steam outlet (57) of a middle pressure cylinder (58) is connected with a deaerator (5) through a deaerator steam inlet pipe (4); the method comprises the steps that a steam extraction port of a low-pressure cylinder (51) is connected with the steam side of a low-pressure heater through a low-pressure heater steam inlet pipe, a deaerator steam inlet regulating valve (3) is arranged on the deaerator steam inlet pipe (4), and a low-pressure heater steam inlet regulating valve is arranged on the low-pressure heater steam inlet pipe, wherein the steam extraction port of the low-pressure cylinder (51) is connected with the low-pressure heater;
s2: collecting voltage and current output by a generator rotor (50) in real time, and obtaining output power and frequency of the generator rotor (50) through collected voltage signals and current signals;
s3: valve opening control instructions of the deaerator steam inlet regulating valve (3) and the low-pressure heater steam inlet regulating valve are obtained through calculation according to the frequency and the output power of the generator rotor (50), and the opening of the deaerator steam inlet regulating valve (3) and the low-pressure heater steam inlet regulating valve is controlled according to the obtained valve opening control instructions, so that the output power and the frequency of the generator rotor (50) are regulated; the method specifically comprises the following steps:
s31: the acquired output frequency f of the generator rotor (50) is differed from the power grid frequency 50Hz to obtain a frequency difference delta f;
s32: passing the frequency difference Δf through a power conversion coefficient K 0 Is converted into a power command and is matched with the current power command P of the steam turbine unit s Difference is made to obtain a new power instruction P N ；
S33: new power instruction P N The signal is divided into two paths of signals, and the first path of new power instruction P N Controlled feedforward coefficient K 1 Converting into a power command signal;
s34: the power command signal passes through the flow conversion coefficient K cq Converting into a flow instruction signal and controlling the opening of a deaerator steam inlet regulating valve (3) and the opening of a low-pressure heater steam inlet regulating valve;
s35: after the deaerator steam inlet regulating valve (3) and the low-pressure heater steam inlet regulating valve act, a second new power instruction P is given N And the generator rotor (50) power real-time value P E Comparing, the deviation is input into PID link, and the PID link outputs new power instruction P with the first path N Controlled feedforward coefficient K 1 The converted signals are summed to form a new P V Instructions, converted into flow instruction signals C V Flow instruction signal C V Simultaneously distributing the deaerator steam inlet regulating valve (3) and the low-pressure heater steam inlet regulating valve;
s36: the deaerator steam inlet regulating valve (3) and the low-pressure heater steam inlet regulating valve act again until a new power instruction P N And the generator rotor (50) power real-time value P E The deviation is zero;
s37: steps S32-S36 are repeated when a new signal frequency difference af occurs.
2. A method of adjusting grid frequency for steam extraction of a steam turbine according to claim 1, wherein: the low-pressure heaters are arranged in a plurality, the number of the steam extraction ports of the low-pressure cylinders (51) is consistent with that of the low-pressure heaters, and the steam extraction ports of each low-pressure cylinder (51) are respectively connected with the steam sides of the corresponding low-pressure heaters through low-pressure heater steam inlet pipes; and each low-pressure heater steam inlet pipe is provided with a corresponding low-pressure heater steam inlet regulating valve for regulating the steam quantity flowing through each low-pressure heater steam inlet pipe.
3. A method of adjusting grid frequency for steam extraction of a steam turbine according to claim 2, wherein: the number of the low-pressure heaters is 4, namely a first low-pressure heater (15), a second low-pressure heater (23), a third low-pressure heater (30) and a fourth low-pressure heater (37);
the low-pressure cylinder (51) is respectively provided with an IV low-pressure cylinder steam extraction port (52), a III low-pressure cylinder steam extraction port (53), an II low-pressure cylinder steam extraction port (54) and an I low-pressure cylinder steam extraction port (55);
the steam extraction port (55) of the first low-pressure cylinder is connected with the first low-pressure heater (15) through a steam inlet pipe (14) of the first low-pressure heater, and a steam inlet regulating valve (13) of the first low-pressure heater, which is electrically connected with a data acquisition and control device (69), is arranged on the steam inlet pipe (14) of the first low-pressure heater; the low-pressure heater inlet pipe (14) is used for extracting steam from the low-pressure cylinder steam extraction port (55) and flowing the steam into the low-pressure heater (15); the second low-pressure cylinder steam extraction port (54) is connected with a second low-pressure heater (23) through a second low-pressure heater steam inlet pipe (22), and a second low-pressure heater steam inlet regulating valve (21) electrically connected with a data acquisition and control device (69) is arranged on the second low-pressure heater steam inlet pipe (22); the second low-pressure heater steam inlet pipe (22) is used for extracting steam from the second low-pressure cylinder steam extraction port (54) and flowing into the second low-pressure heater (23); the third low-pressure cylinder steam extraction port (53) is connected with a third low-pressure heater (30) through a third low-pressure heater steam inlet pipe (29), and a third low-pressure heater steam inlet regulating valve (28) electrically connected with a data acquisition and control device (69) is arranged on the third low-pressure heater steam inlet pipe (29); the third low-pressure heater steam inlet pipe (29) is used for extracting steam from the third low-pressure cylinder steam extraction port (53) and flowing the steam into the third low-pressure heater (30); the fourth low-pressure cylinder steam extraction port (52) is connected with a fourth low-pressure heater (37) through a fourth low-pressure heater steam inlet pipe (36), and a fourth low-pressure heater steam inlet regulating valve (35) electrically connected with a data acquisition and control device (69) is arranged on the fourth low-pressure heater steam inlet pipe (36); the fourth low-pressure heater steam inlet pipe (36) is used for extracting steam from the fourth low-pressure cylinder steam extraction port (52) and flowing into the fourth low-pressure heater (37).
4. A method of adjusting grid frequency for steam extraction of a steam turbine according to claim 1, wherein: the frequency difference Δf=f-50 in step S31.
5. A method of adjusting grid frequency for steam extraction of a steam turbine according to claim 1, wherein: the step S32 further includes converting the frequency difference Δf into a power command after the frequency difference Δf exceeds the dead zone ±Δe.
6. A method for regulating grid frequency for steam turbine extraction as defined in claim 5, wherein: the power conversion coefficient K in the step S32 0 The calculation is as follows:
K 0 =rated power/2.5.
7. A method of adjusting grid frequency for steam extraction of a steam turbine according to claim 1, wherein: the flow conversion coefficient K in the step S34 cq The calculation mode of (2) is as follows:
K cq ＝1/P cq ；
Figure FDA0004158124620000041
wherein eta 0 The power influence coefficient is caused by the change of the steam intake and extraction quantity of the deaerator (5); η (eta) 1 The power influence coefficient is caused by the change of the steam intake and extraction quantity of the first low-pressure heater (15); η (eta) 2 The power influence coefficient is caused by the change of the steam intake and extraction quantity of the II low-pressure heater (23); η (eta) 3 The power influence coefficient is caused by the change of the steam intake and extraction quantity of the third low-pressure heater (30); η (eta) 4 The power influence coefficient is caused by the change of the steam intake and extraction quantity of the IV low-pressure heater (37); q (Q) 0 The steam inlet and extraction amount of the deaerator (5); q (Q) 1 The steam inlet and extraction quantity of the first low-pressure heater (15); q (Q) 2 Heating at a low pressure of type IIThe steam inlet and extraction quantity of the device (23); q (Q) 3 The steam inlet and extraction amount of the third low-pressure heater (30); q (Q) 4 And (5) the steam inlet and steam extraction quantity of the fourth low-pressure heater (37).
8. A method of adjusting grid frequency for steam extraction of a steam turbine according to claim 1, wherein: the flow instruction signal C in the step S35 V Meanwhile, the air inlet regulating valve (3) of the deaerator and the air inlet regulating valve of the low-pressure heater are specifically:
according to the flow command signal C V Obtaining opening signals f corresponding to the deaerator steam inlet regulating valve (3), the I low-pressure heater steam inlet regulating valve (13), the II low-pressure heater steam inlet regulating valve (21), the III low-pressure heater steam inlet regulating valve (28) and the IV low-pressure heater steam inlet regulating valve (35) 0 (C V )、f 1 (C V )、f 2 (C V )、f 3 (C V )、f 4 (C V ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein the control curve y of the deaerator steam inlet regulating valve (3) 0 ＝f 0 (x) The method comprises the steps of carrying out a first treatment on the surface of the Control curve y of steam inlet regulating valve (13) of first low-pressure heater 1 ＝f 1 (x) The method comprises the steps of carrying out a first treatment on the surface of the Control curve y of steam inlet regulating valve (21) of second low-pressure heater 2 ＝f 2 (x) The method comprises the steps of carrying out a first treatment on the surface of the III control curve y of low-pressure heater steam inlet regulating valve (28) 3 ＝f 3 (x) The method comprises the steps of carrying out a first treatment on the surface of the IV control curve y of steam inlet regulating valve (35) of low-pressure heater 4 ＝f 4 (x)。
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