Automatic control method for tripping of high-pressure heater drain pump of thermal power unit

Abstract

The present invention belongs to the field of thermal power generation control technology and specifically discloses a method for automatically controlling the tripping of a high-pressure heater drain pump of a thermal power unit, comprising: step 1, gradually reducing the coal quantity of the thermal power unit at a preset first rate, and causing the thermal power unit to operate at sliding pressure in a turbine tracking mode; step 2, obtaining the real-time coal quantity of the thermal power unit, and regulating the total air volume and primary air pressure according to the real-time coal quantity, while regulating the preset lockout time of the boiler core equipment of the thermal power unit and the number of operations of the control powder system; step 3, regulating the feedwater flow of the feedwater pump, the pressure of the condensate pump, the main steam parameters of the turbine, and the liquid level of the final high-pressure heater; step 4, judging in real time whether the unit load, feedwater flow, main steam parameters, and the liquid level of the final high-pressure heater meet the control termination conditions; if not, repeating steps 2 to 4. The method of the present invention can significantly reduce the number of unplanned outages and greatly improve the operational reliability and safety of the thermal power unit.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal power generation control and discloses an automatic tripping control method for a high-pressure heater drain pump of a thermal power unit, in particular to an automatic tripping control method for a high-pressure heater drain pump of a deaerator-free thermal system. Background Art

[0002] To reduce construction costs, save space for power plant equipment, and simplify the feedwater thermal system, some thermal power units are currently designed to use condensate pumps to provide the water pump with an effective pressure head, ensuring that the feedwater pump has the necessary cavitation margin. Feedwater pump pre-pumps and deaerators are no longer required. This design recycles the high-pressure heater drain pump (HPJ drain pump) back to the feedwater pump inlet pipeline during unit operation, ensuring the recovery of the unit's working fluid and heat, and reducing the unit's heat consumption.

[0003] However, in actual operation of a thermal power unit designed for a deaerator-free thermal system, if the high-pressure heater drain pump trips, the feedwater pump inlet flow rate will drop suddenly by about 20%, causing low feedwater pump inlet pressure, resulting in feedwater pump tripping and unplanned shutdown of the thermal power unit. Therefore, a high-pressure heater drain pump trip under high load will seriously threaten the safe and stable operation of the unit. Summary of the Invention

[0004] The purpose of the present invention is to provide an automatic control method for the tripping of a high-pressure heater drain pump of a thermal power unit, so as to solve the technical problem that the tripping of the high-pressure heater drain pump under high load leads to unplanned shutdown of the thermal power unit, which seriously threatens the safe and stable operation of the thermal power unit.

[0005] The present invention provides a method for automatically controlling the tripping of a high-pressure heater drain pump of a thermal power unit, comprising:

[0006] Step 1: gradually reduce the real-time coal quantity of the thermal power unit at a preset first rate, and make the thermal power unit operate at sliding pressure in a steam turbine tracking mode.

[0007] Step 2: Obtain the real-time coal quantity of the thermal power unit, and adjust the total air volume and primary air pressure according to the real-time coal quantity, and at the same time adjust the preset lock time of the boiler core equipment of the thermal power unit and the operating quantity of the powder control system.

[0008] Step 3: Regulate the feed water flow of the feed water pump, the pressure of the condensate pump, the main steam parameters of the steam turbine and the liquid level of the final high-pressure heater.

[0009] Step 4: Determine in real time whether the unit load, feed water flow, main steam parameters and final high-pressure booster liquid level meet the control end conditions. If not, repeat steps 2 to 4.

[0010] Preferably, regulating the preset locking time of the boiler core equipment of the thermal power unit includes:

[0011] Obtain the real-time load of the thermal power unit.

[0012] After the superheater desuperheating water regulating valve is overrun and closed for 25S to 35S, the design value corresponding to the real-time load is automatically tracked and automatically adjusted.

[0013] After the reheater desuperheating water regulating valve is overrun and closed for 25S to 35S, the design value corresponding to the real-time load is automatically tracked and automatically adjusted.

[0014] Preferably, regulating the preset lockout time of the boiler core equipment of the thermal power unit further includes:

[0015] The automatic control for coal calorific value correction is locked for 115S to 125S and then resumes automatic adjustment. The automatic control for superheat adjustment of coal is locked for 55S to 65S and then resumes automatic adjustment. The automatic control for oxygen correction is locked for 55S to 65S and then resumes automatic adjustment.

[0016] Preferably, regulating the preset lockout time of the boiler core equipment of the thermal power unit further includes:

[0017] Shield the manual cut-off condition when the deviation between the primary fan blade command and feedback is large, and shield the manual cut-off condition when the deviation between the primary wind pressure command and feedback is large.

[0018] Shield the manual cut-off condition when the deviation between the fan blade instruction and feedback is large, and shield the manual cut-off condition when the deviation between the air supply volume instruction and feedback is large.

[0019] Preferably, regulating the water flow rate of the water supply pump specifically includes:

[0020] Lock the water supply pump flow increase for 10S to 20S and then release the lock.

[0021] Switch the third-order inertia time of the water feed pump to 2S to 4S.

[0022] When the feedwater pump inlet pressure is lower than the pressure alarm value corresponding to the real-time load of the thermal power unit, the interlock starts the power frequency standby condensate pump and automatically sets the running condensate pump frequency to 50Hz.

[0023] Preferably, regulating the pressure of the condensate pump specifically includes:

[0024] Determine the feedwater pump inlet pressure corresponding to the real-time load of the thermal power unit.

[0025] The pressure of the condensate pump is regulated to be 0.1 MPa to 0.3 MPa higher than the inlet pressure of the water feed pump and maintained for 1 to 3 minutes.

[0026] Preferably, regulating the main steam parameters of the steam turbine specifically includes:

[0027] The main steam pressure of the steam turbine is gradually reduced to a pressure corresponding to a preset load at a preset second rate.

[0028] Preferably, the control end condition of the unit load is that the unit load stabilizes to a preset load ±30MW and is delayed for 25S to 35S;

[0029] The control end condition of the water flow rate is that the water flow rate is stable to the water flow rate corresponding to the preset load ±50t / h, and the time is delayed by 25S to 35S;

[0030] The control termination conditions of the main steam parameters are: the main steam pressure change rate is ≤0.2MPa / min and the delay is 25S to 35S; the main steam temperature change rate is ≤2℃ / min and the delay is 25S to 35S;

[0031] The control end condition of the final high-pressure liquid level is that the final high-pressure liquid level stabilizes to a preset normal value ±50mm and is delayed by 25S to 35S.

[0032] Preferably, the thermal power unit is operated in a turbine tracking mode with sliding pressure, specifically:

[0033] The automatic power generation control of the unit is automatically released, and the unit control is switched from the coordinated control mode to the steam turbine tracking mode.

[0034] The boiler master control switches from automatic mode to manual mode.

[0035] Preferably, the final coal quantity of the thermal power unit is the coal quantity corresponding to 70% of the rated load.

[0036] Compared with the prior art, the automatic control method for tripping of the high-pressure heater drain pump of a thermal power unit of the present invention has the following beneficial effects:

[0037] The automatic control method for the tripping of the high-pressure heater drain pump of a thermal power unit of the present invention can smoothly realize the full-process automatic control of the thermal power unit after the high-pressure heater drain pump trips, so that the load of the thermal power unit is quickly reduced to a safe load that matches the water supply when the high-pressure heater drain pump is not in operation.

[0038] The present invention realizes automatic control of the tripping of the high-pressure heater drain pump of a thermal power unit without a deaerator thermal system, reduces manual operation, avoids risks such as misoperation, improves the safety of the thermal power unit when the main equipment trips, and lays the foundation for the intelligent construction of the thermal power unit.

[0039] The present invention uses reasonable coal reduction rate and air volume, water supply and other controls to reduce the impact of thermal stress and mechanical stress on equipment such as boilers, turbines, and pipelines, extend the service life of the equipment, and reduce the maintenance cost of thermal power units.

[0040] The automatic control method for tripping of a high-pressure heater drain pump of a thermal power unit of the present invention significantly reduces the number of unplanned outages and greatly improves the operational reliability and safety of the thermal power unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The present invention is a flowchart of a method for automatically controlling the tripping of a high-pressure heater drain pump of a thermal power unit according to an embodiment of the present invention.

[0042] Figure 2 Schematic diagram of the structure of the thermal system in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0043] In the following description, specific details such as particular system structures and techniques are provided for purposes of illustration, not limitation, to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0044] In the embodiment of the present invention, the activation conditions for the automatic control of the tripping of the high-pressure heater drain pump of a thermal power unit are that the load of the thermal power unit is greater than 75% of the rated load; the load control mode of the thermal power unit is the coordinated control mode or the turbine tracking mode (Turbine Follow Mode, TF for short); and the automatic control system for the tripping of the high-pressure heater drain pump is activated by pressing a button.

[0045] The triggering condition for the automatic control of the tripping of the high-pressure heater drain pumps of the thermal power unit in the embodiment of the present invention is that both high-pressure heater drain pumps trip, and the delay is 1 to 3 seconds. For example, it can be 1 second, 2 seconds, 3 seconds, etc., and is preferably 2 seconds.

[0046] The embodiment of the present invention provides a method for automatically controlling the tripping of a high-pressure heater drain pump of a thermal power unit, including automatic control of the unit coordination mode, automatic control of the boiler side and automatic control of the steam turbine side, specifically as follows Figure 1 Shown, including:

[0047] Step 1: gradually reduce the real-time coal quantity of the thermal power unit at a preset first rate, and make the thermal power unit operate in a turbine tracking mode with sliding pressure, wherein the first rate is 5 t / s to 15 t / s, preferably 10 t / s.

[0048] This involves operating the thermal power unit in turbine-tracking mode with sliding pressure. Specifically, the unit's Automatic Generation Control (AGC) is automatically disengaged and the unit's control mode is switched from coordinated control to turbine-tracking mode. Simultaneously, the boiler master control mode is switched from automatic to manual.

[0049] The above-mentioned stepwise reduction of the coal quantity of the thermal power unit at a preset first rate is specifically as follows: the coal quantity of the thermal power unit is gradually reduced to the coal quantity corresponding to 70% of the rated load at the preset first rate, and 70% of the rated load is the maximum load at which the unit can operate safely and stably after the high-pressure heater drain is recovered to the condenser.

[0050] The amount of coal B ( w ) and unit load w The functional relationship between them is:

[0051] (1)

[0052] Where: B ( w ) is the real-time coal quantity of the thermal power unit, in t / h; w is the real-time load of the unit, in MW; B des The design coal quantity corresponding to the rated load, in t / h; W 0 is the rated load of the unit, in MW; Q net,design The calorific value of the designed coal type is MJ / Kg; Q net,actual The actual calorific value of the coal, in MJ / Kg; K 1 is a constant, and its unit is t / h.

[0053] Step 1 of the embodiment of the present invention belongs to automatic control in a coordinated manner of the units.

[0054] Step 2: Obtain the real-time coal quantity of the thermal power unit, and adjust the total air volume and primary air pressure according to the real-time coal quantity. At the same time, adjust the preset lock time of the boiler core equipment of the thermal power unit and the operating quantity of the control powder system.

[0055] The embodiment of the present invention adjusts the number of running pulverizing systems specifically as follows: during the coal reduction process, the number of pulverizing systems put into operation is determined; when the total number of pulverizing systems put into operation is greater than 4, the redundant pulverizing systems are tripped, and 4 pulverizing systems are kept in operation.

[0056] The automatic control of the total air volume is determined according to the curve function of the real-time coal volume and the total air volume as shown in formula (2), and the final total air volume is the total air volume corresponding to the coal volume of 70% rated load.

[0057] (2)

[0058] Where: Q ( b ) is the total air volume, in t / h; B ( w ) is the real-time coal quantity, in t / h;K 2 is the coefficient constant, dimensionless; K 3 is a constant, the unit is t / h.

[0059] The automatic control of the primary air pressure is determined according to the real-time coal quantity and the primary air pressure curve function as shown in formula (3), and the final primary air pressure is the primary air pressure corresponding to the coal quantity of 70% of the rated load.

[0060] (3)

[0061] Where: P ( b ) is the primary wind pressure, in kPa; B ( w ) is the real-time coal quantity, in t / h; K 4 is a constant, the unit is kPa / (t / h); K 5 is a constant, the unit is kPa.

[0062] The embodiment of the present invention regulates the preset locking time of the core equipment of the boiler of a thermal power unit, including:

[0063] Get the real-time load of thermal power units.

[0064] After the superheater desuperheating water regulating valve is overrun and closed for 25S to 35S, the design value corresponding to the real-time load is automatically tracked and automatically adjusted. For example, the overrun closing can be 25S, 30S, 35S, etc., preferably 30S.

[0065] After the reheater desuperheating water regulating valve is overridden and closed for 25 to 35 seconds, the design value corresponding to the real-time load is automatically tracked and automatically adjusted. For example, the overriding closing period can be 25 seconds, 30 seconds, 35 seconds, etc., preferably 30 seconds.

[0066] The embodiment of the present invention regulates the preset locking time of the core equipment of the boiler of the thermal power unit, and further includes:

[0067] The coal calorific value (BTU) correction automatic control lockout period is set to 115 to 125 seconds before resuming automatic regulation. The superheat adjustment coal feeding lockout period is set to 55 to 65 seconds before resuming automatic regulation. The oxygen correction lockout period is set to 55 to 65 seconds before resuming automatic regulation. For example, the coal calorific value (BTU) correction automatic control lockout period can be 115, 120, or 125 seconds, preferably 120 seconds; the superheat adjustment coal feeding lockout period can be 55, 60, or 65 seconds, preferably 60 seconds; and the oxygen correction lockout period can be 55, 60, or 65 seconds, preferably 60 seconds.

[0068] Furthermore, regulating the preset lockout time of the core equipment of the boiler of the thermal power unit also includes:

[0069] Shield the manual cut-off condition when the deviation between the primary fan blade command and feedback is large, and shield the manual cut-off condition when the deviation between the primary wind pressure command and feedback is large.

[0070] Shield the manual cut-off condition when the deviation between the fan blade instruction and feedback is large, and shield the manual cut-off condition when the deviation between the air supply volume instruction and feedback is large.

[0071] The above step 2 in the embodiment of the present invention belongs to boiler-side automatic control.

[0072] Step 3: Regulate the feed water flow of the feed water pump, the pressure of the condensate pump, the main steam parameters of the steam turbine and the liquid level of the final high-pressure heater.

[0073] In an embodiment of the present invention, the water flow rate of the feedwater pump is regulated, specifically including: locking the flow rate increase of the feedwater pump for 10S to 20S and then releasing the lock. For example, the flow rate increase of the feedwater pump is locked for 10S, 15S, 20S, etc., preferably 15S. The third-order inertia time automatically set for the feedwater pump is switched from 25S to 2S to 4S, preferably 3S, so as to match the dynamic lag and inertia of the feedwater. When the inlet pressure of the feedwater pump is lower than the pressure alarm value corresponding to the real-time load of the thermal power unit, the industrial frequency standby condensate pump is started by interlock, and the frequency of the running condensate pump is automatically set to 50Hz.

[0074] The embodiment of the present invention regulates the pressure of the condensate pump, specifically including: determining the feed water pump inlet pressure corresponding to the real-time load of the thermal power unit, and then regulating the pressure of the condensate pump to 0.1MPa to 0.3MPa higher than the feed water pump inlet pressure, preferably 0.2Mpa, and maintaining it for 1min to 3min, preferably 2min.

[0075] The embodiment of the present invention regulates the main steam parameters of the steam turbine, specifically including: gradually reducing the main steam pressure of the steam turbine to a pressure corresponding to a preset load at a preset second rate.

[0076] In the embodiment of the present invention, the turbine valve is adjusted to control the main steam pressure to decline at a second rate until it declines to the main steam pressure corresponding to 70% of the rated load. V p 0.7 MPa / min, which can be modified according to the actual boiler heat load inertia.

[0077] In step 3, the liquid level of the last stage high pressure heater is regulated, specifically: the last stage high pressure heater drain is switched from the high pressure heater drain pump to the emergency drain, the emergency drain regulating valve is automatically put into operation, and the liquid level of the last stage high pressure heater is tracked before the high pressure heater drain pump trips.

[0078] Step 4: Determine in real time whether the unit load, feed water flow, main steam parameters and final high-pressure booster liquid level meet the control end conditions. If not, repeat steps 2 to 4.

[0079] The control end condition of the unit load is that the unit load stabilizes to the preset load ±30MW, and the delay is 25S to 35S, preferably 30S.

[0080] The control end condition of the water supply flow is that the water supply flow stabilizes to the water supply flow corresponding to the preset load ±50t / h, and is delayed by 25S to 35S, preferably 30S.

[0081] The control termination conditions of the main steam parameters are that the main steam pressure change rate is ≤0.2MPa / min and the time is delayed by 25S to 35S, preferably 30S, and the main steam temperature change rate is ≤2℃ / min and the time is delayed by 25S to 35S, preferably 30S.

[0082] The control end condition of the final high-pressure liquid level is that the final high-pressure liquid level stabilizes to a preset normal value ±50mm, and is delayed by 25S to 35S, preferably 30S.

[0083] The automatic control method for the tripping of the high-pressure heater drain pump of a thermal power unit of the present invention can smoothly realize the full-process automatic control of the thermal power unit after the high-pressure heater drain pump trips, so that the load of the thermal power unit is quickly reduced to a safe load that matches the water supply when the high-pressure heater drain pump is not in operation.

[0084] The present invention realizes automatic control of the tripping of the high-pressure heater drain pump of a thermal power unit without a deaerator thermal system, reduces manual operation, avoids risks such as misoperation, improves the safety of the unit when the main equipment trips, and lays the foundation for the intelligent construction of thermal power units.

[0085] The present invention uses reasonable coal reduction rate and air volume, water supply and other controls to reduce the impact of thermal stress and mechanical stress on equipment such as boilers, turbines, and pipelines, extend the service life of the equipment, and reduce the maintenance cost of thermal power units.

[0086] The automatic control method for tripping of a high-pressure heater drain pump of a thermal power unit of the present invention significantly reduces the number of unplanned outages and greatly improves the operational reliability and safety of the thermal power unit.

[0087] The effectiveness of the method of the present invention will be verified with specific examples below.

[0088] Taking a 660MW ultra-supercritical power plant in Shaanxi as an example, the boiler type is a high-efficiency ultra-supercritical parameter once-through furnace with single-stage intermediate reheat, a single furnace, balanced ventilation, and solid slag removal. The design utilizes a medium-speed mill cooling primary fan and a positive-pressure direct-blowing pulverizing system. Each furnace is equipped with six medium-speed mills, five in operation and one in standby (under BMCR conditions), two 50%-capacity axial-flow induced draft fans with adjustable blades, two 50%-capacity axial-flow primary fans, and two 50%-capacity axial-flow forced draft fans.

[0089] The steam turbine is an ultra-supercritical, single-intermediate reheat, three-cylinder, two-exhaust, single-shaft, indirect air-cooled condensing type.

[0090] This thermal system has no deaerator, no steam pump pre-pump, and uses the condensate pump as the power to provide the feed water pump with the necessary NPSH pressure head. It is designed with two high-pressure heater drain pumps, three high-pressure heaters, and an external steam cooler. The drain flows step by step to the No. 3 high-pressure heater, and is pressurized by the high-pressure heater drain pump and supplied to the feed water pump inlet pipe; the No. 4 low-pressure heater flows step by step to the No. 7 low-pressure heater, and is pressurized by the low-pressure heater drain pump and supplied to the No. 6 low-pressure heater inlet condensate pipe. Figure 2 shown.

[0091] The thermal system is designed with three 50% capacity condensate pumps, which can operate at rated frequency or variable frequency.

[0092] Unit status before test:

[0093] The unit load is 594MW (90% rated load), AGC is engaged, and the coordinated control mode is engaged;

[0094] The liquid level of No. 3 high-pressure heater is 0mm, the high-pressure heater drain pump A is running, the condensate pump A is running at a frequency of 43.2Hz, the condensate pump C is running at a frequency of 43.2Hz, and the condensate pump B is in standby mode at the power frequency;

[0095] The total coal volume is 302t / h, the pneumatic feed water pumps A and B are running in parallel, the feed water flow is 1745t / h, and the five pulverizing systems A, B, C, D, and E are running. At this time, the automatic control system for the high-pressure drain pump tripping is verified.

[0096] Determination of the conditions for automatic control of tripping of the high-pressure drain pump in the embodiment of the present invention:

[0097] (1) Unit load 594MW (greater than 75% of rated load);

[0098] (2) The load control mode of the unit is coordinated control mode;

[0099] (3) The button of the automatic control system for the tripping of the high-pressure drain pump has been activated;

[0100] Determination of the triggering conditions for the automatic control of the tripping of the high-pressure drain pump in the embodiment of the present invention:

[0101] Release the interlock of HV heater drain pump B, put HV heater drain pump B into operation prohibition, and manually stop HV heater drain pump A on site, then the logic of both HV heater drain pumps tripping will be triggered, with a delay of 2 seconds;

[0102] The automatic control of the high-pressure heater drain pump tripping in the embodiment of the present invention is as follows:

[0103] a. Automatic control of unit coordination mode

[0104] ① The AGC control of the unit is automatically released;

[0105] ②The boiler master control switches from automatic mode to manual mode;

[0106] ③ The unit control mode is switched from coordinated control mode to TF control mode;

[0107] ④ The fuel master control reduces the coal flow rate by 10 t / s to 231 t / h (the coal flow rate corresponding to 70% of the rated load);

[0108] b. Automatic control of boiler side system

[0109] ① Before the high-pressure drain pump trips, the five pulverizing systems A, B, C, D, and E are running. The pulverizing system A is interlocked and stopped, while the pulverizing systems B, C, D, and E are kept running;

[0110] ② The total air volume gradually decreased from 2106 t / h to 1622 t / h (the total air volume corresponding to 70% of the rated load coal volume), and the process coal volume was tracked in real time;

[0111] ③ The primary air pressure gradually decreases from 9.6 KPa to 8.0 KPa (the primary air pressure corresponding to 70% rated load coal quantity). The process coal quantity is tracked in real time. The output of each pulverizing system is balanced. The correction value is 0 KPa, and the final primary air pressure target value is 8.0 KPa.

[0112] ④ 30 seconds after the superheater desuperheating water regulating valve is overrun and closed, the unit load is 550MW, the superheater first-stage desuperheating water regulating valve tracks 512℃ and automatically adjusts, and the superheater second-stage desuperheating water regulating valve tracks 542℃ and automatically adjusts;

[0113] ⑤ After the reheater desuperheating water regulating valve is overrun and closed for 30 seconds, the unit load is 550MW, and the reheater desuperheating water regulating valve tracks 521℃ and automatically adjusts;

[0114] ⑥ The automatic control of coal calorific value (BTU) correction will resume automatic adjustment after 120 seconds of lockout; the automatic adjustment of superheat adjustment coal feeding will resume automatic adjustment after 60 seconds of lockout; the automatic adjustment of oxygen content correction will resume automatic adjustment after 60 seconds of lockout;

[0115] ⑦Shield the manual cut-off condition when the deviation between the primary fan blade command and feedback is large, and shield the manual cut-off condition when the deviation between the primary wind pressure command and feedback is large;

[0116] ⑧ Shield the manual cut-off condition when the deviation between the fan blade instruction and feedback is large, and shield the manual cut-off condition when the deviation between the air supply volume instruction and feedback is large.

[0117] c. Automatic control on the steam turbine side

[0118] ① The outlet valves of the high-pressure heater drain pump A and high-pressure heater drain pump B are closed, and the drain is switched from the high-pressure heater drain pump line to the emergency drain. The No. 3 high-pressure heater emergency drain regulating valve is put into automatic mode, and the automatic value tracks 0mm;

[0119] ② The turbine regulating valve controls the main steam pressure to drop at a rate of 0.7 MPa / min, down to 21.6 MPa (the sliding pressure parameter corresponding to 70% of the rated load);

[0120] ③ The condensate pump frequency conversion automatically controls the feed pump inlet pressure. The corresponding broken line function value under the current load is 1.83MPa, and then it is automatically increased to 2.03MPa on this basis and maintained for 2 minutes;

[0121] ④ The feedwater pump inlet pressure dropped to a minimum of 1.48 MPa, which did not reach the feedwater pump inlet low pressure alarm value, and the condensate pump B power frequency standby interlock start was not triggered;

[0122] ⑤ Lock the water supply pump flow increase for 15S and then release the lock increase;

[0123] ⑥ The third-order inertia time automatically set for water supply is switched from 25S to 3S to match the dynamic lag and inertia of water supply.

[0124] (4) The conditions for determining whether the high-pressure drain pump tripping automatic control system is completed are:

[0125] a. The unit load stabilizes to 471 MW, with a delay of 30 seconds;

[0126] b. The unit feed water flow rate is stable at 1352 t / h;

[0127] c. The No. 3 high pressure liquid level is stable to 0mm;

[0128] d. Main steam pressure 21.6 MPa, main steam pressure change rate 0.02 MPa / min, delay 30S;

[0129] e. Main steam temperature is 602 ℃, main steam temperature change rate is 0.32 ℃ / min, and delay is 30S.

[0130] The entire process of automatic control of the tripping of the high-pressure heater drain pump of a thermal power unit according to the embodiment of the present invention requires no manual operation or judgment, thereby achieving automatic control of the entire process.

[0131] During the test, the unit load dropped steadily to 471 MW at the expected rate, and all key operating parameters were maintained within the safe operating margin during the entire automatic control process. Ultimately, the unit's systems and parameters were stable.

[0132] The main parameters before and after the high-pressure heater drain pump trip triggers automatic control in a 660MW ultra-supercritical power station in Shaanxi are shown in Table 1.

[0133] Table 1 Main parameters before and after all high-pressure drain pumps tripped

[0134]

[0135] The fully automatic control sequence and reasonable key parameter regulation of the present invention realize the full-process smooth automatic control of the thermal power unit after the high-pressure heater drain pump trips, so that the load of the thermal power unit is quickly reduced to a safe load, the number of unplanned outages is reduced, and the operating reliability and safety of the unit are improved.

[0136] The above descriptions are merely several embodiments of the present invention and do not constitute any form of limitation to the present invention. Although the present invention is disclosed as above in terms of preferred embodiments, they are not intended to limit the present invention. Any technician familiar with the present profession, without departing from the scope of the technical solution of the present invention, who makes slight changes or modifications using the technical contents disclosed above, is equivalent to an equivalent implementation case and falls within the scope of the technical solution.

Claims

1. A method for automatically controlling the tripping of a high-pressure heater drain pump of a thermal power unit, characterized in that: include: Step 1: gradually reducing the real-time coal quantity of the thermal power unit at a preset first rate, and making the thermal power unit operate in a turbine tracking mode with sliding pressure; Step 2: Obtain the real-time coal quantity of the thermal power unit, and adjust the total air volume and primary air pressure according to the real-time coal quantity, and at the same time adjust the preset lockout time of the boiler core equipment of the thermal power unit and the operating quantity of the pulverized coal control system; Step 3: Regulate the feedwater flow of the feedwater pump, the pressure of the condensate pump, the main steam parameters of the steam turbine, and the liquid level of the final high-pressure heater; Step 4: determine in real time whether the unit load, the feed water flow, the main steam parameters and the final high-pressure heater liquid level meet the control end condition; if not, repeat steps 2 to 4; Regulating the preset lockout time of the boiler core equipment of the thermal power unit, including: Obtaining the real-time load of the thermal power unit; After the superheater desuperheating water regulating valve is overrun and closed for 25 to 35 seconds, the design value corresponding to the real-time load is automatically tracked and automatically adjusted; After the reheater desuperheating water regulating valve is overrun and closed for 25S to 35S, the design value corresponding to the real-time load is automatically tracked and automatically adjusted.

2. The automatic control method for tripping of a high-pressure heater drain pump of a thermal power unit according to claim 1, characterized in that: Regulating the preset lockout time of the boiler core equipment of the thermal power unit, further comprising: The automatic control for coal calorific value correction is locked for 115S to 125S and then resumes automatic adjustment. The automatic control for superheat adjustment of coal is locked for 55S to 65S and then resumes automatic adjustment. The automatic control for oxygen correction is locked for 55S to 65S and then resumes automatic adjustment.

3. The automatic control method for tripping of a high-pressure heater drain pump of a thermal power unit according to claim 1, characterized in that: Regulating the preset lockout time of the boiler core equipment of the thermal power unit, further comprising: Shield the manual cut-off condition when the deviation between the primary fan blade command and feedback is large, and shield the manual cut-off condition when the deviation between the primary wind pressure command and feedback is large; Shield the manual cut-off condition when the deviation between the fan blade instruction and feedback is large, and shield the manual cut-off condition when the deviation between the air supply volume instruction and feedback is large.

4. The automatic control method for tripping of a high-pressure heater drain pump of a thermal power unit according to claim 1, characterized in that: Regulate the water flow of the water pump, including: Lock the water supply pump flow increase for 10S to 20S and then release the lock increase; Switch the third-order inertia time of the water feed pump to 2S to 4S; When the feedwater pump inlet pressure is lower than the pressure alarm value corresponding to the real-time load of the thermal power unit, the interlock starts the power frequency standby condensate pump and automatically sets the running condensate pump frequency to 50Hz.

5. The automatic control method for tripping of a high-pressure heater drain pump of a thermal power unit according to claim 4, characterized in that: Regulate the pressure of the condensate pump, including: Determine the feedwater pump inlet pressure corresponding to the real-time load of the thermal power unit; The pressure of the condensate pump is regulated to be 0.1 MPa to 0.3 MPa higher than the inlet pressure of the water feed pump and maintained for 1 to 3 minutes.

6. The automatic control method for tripping of a high-pressure heater drain pump of a thermal power unit according to claim 1, characterized in that: Control the main steam parameters of the steam turbine, including: The main steam pressure of the steam turbine is gradually reduced to a pressure corresponding to a preset load at a preset second rate.

7. The automatic control method for tripping of a high-pressure heater drain pump of a thermal power unit according to claim 1, characterized in that: The control end condition of the unit load is that the unit load stabilizes to the preset load ±30MW and is delayed by 25S to 35S; The control end condition of the water flow rate is that the water flow rate is stable to the water flow rate corresponding to the preset load ±50t / h, and the time is delayed by 25S to 35S; The control termination conditions of the main steam parameters are: the main steam pressure change rate is ≤0.2MPa / min and the delay is 25S to 35S; the main steam temperature change rate is ≤2℃ / min and the delay is 25S to 35S; The control end condition of the final high-pressure liquid level is that the final high-pressure liquid level stabilizes to a preset normal value ±50mm and is delayed by 25S to 35S.

8. The automatic control method for tripping of a high-pressure heater drain pump of a thermal power unit according to claim 1, characterized in that: The thermal power unit is operated in a turbine tracking mode with sliding pressure, specifically: Automatically release the unit's automatic power generation control and switch the unit's control from coordinated control mode to turbine tracking mode; The boiler master control switches from automatic mode to manual mode.

9. The automatic control method for tripping of a high-pressure heater drain pump of a thermal power unit according to claim 1, characterized in that: The final coal quantity of a thermal power unit is the coal quantity corresponding to 70% of the rated load.

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