Control method for rapid stability of unit after accident separation of Gaojia unit

Abstract

The present application relates to a kind of high-gas group accident control method after unit fast stabilization, when the unit high-gas group is decoupled, the operation state of the unit is adjusted by quickly reducing the water intake of boiler and reducing the real-time target load of unit, so that the load and main steam parameter of unit quickly reach stable state after high-gas group decoupling.In the present application, according to the unit high-gas decoupling unit condition, the feedwater flow is quickly reduced, and the main steam temperature can be controlled well in closed-loop mode while ensuring the working environment of desuperheating water, and a new balance can be quickly established to stabilize the unit operation;It greatly reduces the monitoring and operation workload of operating personnel, reduces the work misoperation, and ensures the safety of unit and power grid.

Description

Technical Field

[0001] This invention belongs to the technical field of thermal power units and relates to a control method for rapid and stable operation of the unit after the high-pressure heater unit is disconnected due to an accident. Background Technology

[0002] Large bypass high-pressure heater units are commonly designed and installed in large thermal power units in my country, such as... Figure 1 As shown, a large thermal power unit includes a boiler Bo, a high-pressure cylinder HP, an intermediate-pressure cylinder MP, a low-pressure cylinder LP, high-pressure heaters (H1, H2, H3), low-pressure heaters (H5, H6, H7, H8), a generator Dy, a condenser Co, a condensate pump CP, a deaerator HD, a feedwater pump turbine SP, and a feedwater pump GP. The high-pressure cylinder HP, intermediate-pressure cylinder MP, low-pressure cylinder LP, and generator Dy are coaxially arranged and connected by a connecting shaft PS. During normal operation, the three high-pressure heaters H1, H2, and H3 are connected in series to form a piping system and are controlled uniformly. The high-temperature steam output from the boiler Bo passes through the high-pressure cylinder HP, intermediate-pressure cylinder MP, and low-pressure cylinder LP in sequence. Part of the steam is used to generate electricity for the generator Dy, and the other part is condensed by the condenser Co and then sent to the deaerator HD via the condensate pump CP, low-pressure heaters H8, H7, H6, and H5. During this process, the steam in the low-pressure cylinder LP heats the water in the low-pressure heaters H8, H7, H6, and H5. Afterwards, the feedwater pump GP sends water into the high-pressure heaters H3, H2, and H1. The steam from the high-pressure cylinder HP and the intermediate-pressure cylinder MP heats the water in the high-pressure heaters H3, H2, and H1 in stages, and then sends it to the boiler Bo through the bypass control valve V2 and the feedwater regulating valve V1.

[0003] Due to limited space, no isolation valves or separate bypasses were installed between the high-pressure heaters H1, H2, and H3. However, for the safety and reliability of the unit, the high-pressure heaters H1, H2, and H3 were combined into one unit (referred to as the "high-pressure heater group"). A three-way valve TWV was installed at the inlet of high-pressure heater H3, and a bypass channel BP was led out to connect between the feedwater regulating valve V1 and the bypass control valve V2, thus forming a high-pressure heater feedwater bypass (referred to as the "high-pressure heater bypass"). This simplifies the on-site piping and makes control simple and clear. When a fault occurs in the high-pressure heater group of the thermal power unit, the bypass control valve V2 closes, and the feedwater from the feedwater pump GP will pass through the high-pressure heater group inlet three-way valve TWV, urgently switching to the bypass channel BP, and the high-pressure heater group will be disconnected and withdrawn from the feedwater system. This method has proven to provide good protection for equipment safety on site. However, the biggest problem with this control method is that the system has a large inertia. When the high-pressure heater is disconnected, it will cause a great impact on the boiler and turbine, and may even induce major accidents such as dynamic and static collisions and friction, or trigger the unit to trip.

[0004] Currently, after the high-pressure heater unit is disconnected from the grid, the main problems in the speed control of thermal power units are as follows:

[0005] (1) At present, thermal power units are generally large-capacity and high-parameter units, and generally adopt a regenerative steam extraction system to extract steam from the high, medium and low pressure cylinders of the steam turbine to heat the boiler feedwater and improve the economy of the entire unit. However, due to the high steam parameters of the high and medium pressure cylinders, once the high pressure heater is disconnected, this steam will do work in the steam turbine, resulting in a short-term increase in power (based on the transmission time from the steam turbine to the generator).

[0006] (2) When the unit is under high load, the instantaneous steam pressure and temperature are too high, which can easily cause excessive stress on the internal components of the turbine and damage the equipment.

[0007] (3) After the high-pressure heater is disconnected, the speed regulation system is mainly based on load adjustment. Due to the significant reduction in steam extraction, the unit load will increase significantly in a short period of time. The regulating valve will automatically decrease, which will cause the working fluid flow of the entire boiler heat exchange surface to stagnate. The pressure and temperature will rise in a short period of time, affecting the safety of the unit.

[0008] (4) Due to the pressure rise and stagnation, the superheated steam and reheated steam desuperheating water (the superheated steam desuperheating water is taken from the feedwater pump outlet, see...) Figure 1 If the pressure differential is insufficient, the desuperheating water of the unit may not work effectively, causing the superheater and reheater tubes to burst.

[0009] (5) Due to the shutdown of several high-pressure heaters, the temperature of the main feedwater of the unit will drop by more than 90°. These feedwaters need to absorb a large amount of heat from the furnace in a short period of time, causing the unit to stagnate and then the temperature rises briefly before dropping rapidly. If not controlled properly, the temperature of the steam entering the cylinder will drop sharply, and even the steam will carry water, causing serious accidents such as dynamic and static collisions of the unit. Summary of the Invention

[0010] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a control method for rapid and stable operation of the unit after the high-pressure heater group is disconnected due to an accident.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] A control method for rapid stabilization of a unit after the high-pressure heater group is disconnected from the grid. When the high-pressure heater group is disconnected from the grid, the operating status of the unit is adjusted by rapidly reducing the boiler water intake and lowering the real-time target load of the unit, so that the unit's load and main steam parameters can quickly reach a stable state after the high-pressure heater group is disconnected from the grid.

[0013] Furthermore, methods for rapidly reducing boiler feedwater and lowering the unit's real-time target load include the following steps:

[0014] S110. The target load of the unit operating condition at the time of high-pressure heater disconnection is used as the initial real-time target load. Eb ;

[0015] S120, When the unit's current actual load E When the real-time target load is greater than or equal to the preset load threshold, E b If the load remains unchanged, proceed to step S130; if the current actual load of the unit is less than the load threshold, proceed to step S140.

[0016] S130. Gradually reduce the feedwater flow rate at the boiler inlet and monitor the actual load of the unit. E b Whether to reduce until the actual load of the unit. E b After the descent begins, proceed with step S140.

[0017] S140. Gradually reduce the feedwater flow rate at the boiler inlet and gradually lower the real-time target load. E b This enables the unit to achieve its real-time target load. E b It is matched with the operating conditions of the unit.

[0018] Furthermore, in steps S130 and S140, the method for gradually reducing the feedwater flow rate at the boiler inlet includes the following steps:

[0019] S210. Calculate the target value of feedwater at the boiler inlet. F o ;

[0020] S220, by regulating the opening of the feedwater regulating valve and the speed of the feedwater pump turbine, the feedwater flow rate at the boiler inlet is reduced to the target feedwater value. F o ;

[0021] S230, Recalculate the target value for water supply F o Return to step S220.

[0022] Furthermore, in steps S210 and S230, the target value for water supply... F o The calculation formula is:

[0023] F o =F-λF E

[0024] in, F This indicates the real-time feedwater flow rate at the boiler inlet; λ This represents the conversion factor for the steam extraction capacity of the high-pressure heater group; FE This represents the total steam extraction volume of the high-pressure heater group during normal unit operation, under the unit's operating conditions when the high-pressure heater group is disconnected.

[0025] Furthermore, the conversion factor for the extraction steam volume of the high-pressure heater group... λ The value range is 0.3 to 0.8.

[0026] Furthermore, by cyclically adjusting the opening of the feedwater regulating valve and the speed of the feedwater pump turbine, the feedwater flow rate at the boiler inlet is reduced to the target feedwater value. F o The method is as follows:

[0027] Calculate the outlet pressure of the water supply pump P G With the main steam pressure of the unit P m The real-time difference, when the real-time difference is less than the preset first pressure difference constant. K At time 1, the feedwater flow rate at the boiler inlet is reduced by adjusting the opening of the feedwater regulating valve; when the real-time difference is greater than or equal to the preset first pressure difference constant... K At time 1, the feedwater flow rate at the boiler inlet is reduced by adjusting the turbine speed of the feedwater pump;

[0028] Then, the outlet pressure of the water pump is calculated in real time. P G With the main steam pressure of the unit P m The real-time difference, when the feedwater flow rate at the boiler inlet is reduced by adjusting the opening of the feedwater regulating valve, if the real-time difference is less than the preset second pressure difference constant. K At time 2, the system switches to reducing the feedwater flow rate at the boiler inlet by adjusting the speed of the feedwater pump turbine. When reducing the feedwater flow rate at the boiler inlet by adjusting the speed of the feedwater pump turbine, if the real-time difference is greater than or equal to the preset third pressure difference constant... K At time 3, the system switches to reducing the feedwater flow rate at the boiler inlet by adjusting the turbine speed of the feedwater pump.

[0029] Furthermore, reduce the real-time target load. E b The method is as follows:

[0030] Real-time comparison of the current actual load of the unit E With real-time target load E b If the current actual load E Less than or equal to the real-time target load E b Then the real-time target load will be... E b The value decreased megawatts;

[0031] in, λ This represents the conversion factor for the steam extraction capacity of the high-pressure heater group; F E This represents the total steam extraction volume of the high-pressure heater group when the unit is operating normally, under the condition of the unit being disconnected from the high-pressure heater group; m This indicates the steam consumption for power generation by the generator unit.

[0032] In this invention, the pressure of the superheater desuperheating water is increased according to the load and main steam pressure to prevent the superheater from failing due to excessively high steam pressure and insufficient desuperheating water flow during stagnation, which could lead to serious accidents such as steam and tube wall overheating. When the calorific value of the feedwater entering the boiler drops significantly after the high-pressure heater is disconnected, the feedwater flow can be quickly and orderly reduced to ensure that the desuperheating water operates in a closed-loop manner, effectively controlling the main steam temperature and achieving a new energy balance. The control process requires no operator intervention, greatly reducing the monitoring and operational workload of operators, significantly lowering safety hazards, and effectively and accurately ensuring the safe and stable operation of the unit and the power grid. Attached Figure Description

[0033] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0034] Figure 1 This is a schematic diagram of the typical thermal system of a large thermal power unit with one intermediate reheat.

[0035] Figure 2 A flowchart for quickly reducing the boiler's water intake and lowering the unit's real-time target load.

[0036] Figure 3 A flowchart for gradually reducing the feedwater flow rate at the boiler inlet.

[0037] Figure 4 This is a per-unit parameter diagram of a 600MW subcritical unit with high-pressure heater disconnection at 370MW operating conditions.

[0038] Figure 5 This is a per-unit parameter diagram of a 660MW supercritical unit with high-pressure heater disconnection at 640MW operating conditions.

[0039] Figure 6 This is a per-unit parameter diagram of a 660MW supercritical unit with high-pressure heater disconnection at 370MW operating conditions. Detailed Implementation

[0040] The following specific examples illustrate the implementation of the present invention. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0041] like Figure 2 As shown, a preferred embodiment of the control method for rapid stabilization of the unit after the high-pressure heater group accident is disconnected according to the present invention adopts the following method for control: When the high-pressure heater group of the unit is disconnected, the operating state of the unit is adjusted by rapidly reducing the boiler water intake and reducing the real-time target load of the unit, so that the load and main steam parameters (including main steam pressure and main steam temperature) of the unit quickly reach a stable state after the high-pressure heater group is disconnected, thereby enabling the unit's operating state to quickly reach a new equilibrium after the high-pressure heater group is disconnected, ensuring the stable operation of the unit.

[0042] The method for rapidly reducing the boiler's water intake and lowering the unit's real-time target load includes the following steps:

[0043] S110. The target load of the unit operating condition at the time of high-pressure heater disconnection is used as the initial real-time target load. E b For example, if the unit is operating at full load when it is disconnected from the grid, then the initial real-time target load is... E O When the unit is disconnected from the grid, it is operating at 80% load; therefore, the initial real-time target load is 0.8. E O .

[0044] S120. Obtain the actual operating data of the unit, determine the unit load range based on load comparison, and immediately determine the load-specific operating procedure according to the situation, and simultaneously begin to reduce the boiler feedwater. Both the load reduction and feedwater reduction are calculated based on the converted steam extraction rate. When the unit's current actual load... E When the real-time target load is greater than or equal to the preset load threshold, E b If the load remains unchanged, proceed to step S130; if the current actual load of the unit is less than the load threshold, proceed to step S140. The load threshold can be 0.9. E O Furthermore, an additional 10MW of redundancy can be added on top of this.

[0045] S130. Gradually reduce the feedwater flow rate at the boiler inlet and monitor the actual load of the unit. E b Whether to reduce until the actual load of the unit. E b After the descent begins, execute step S140. (For example...) Figure 3As shown, the method of gradually reducing the feedwater flow rate at the boiler inlet may include the following steps:

[0046] S210. Calculate the target value of feedwater at the boiler inlet. F o The calculation formula is as follows:

[0047] F o =F-λF E

[0048] in, F This indicates the feedwater flow rate at the boiler inlet. In this step, F The value is the feedwater flow rate at the boiler inlet when the high-pressure heater group is disconnected.

[0049] λ This represents the conversion factor for the steam extraction capacity of the high-pressure heater group; λ The theoretical enthalpy drop of the corresponding unit's design steam can be calculated based on thermodynamic calculations. ΔH Subtracting the enthalpy drop of the part that has already generated electricity ΔH The result formed is then compared with the theoretical steam enthalpy drop value of the unit design, i.e., (1- ΔH 1 / ΔH Based on this, the total result after superimposing each extraction steam segment; considering that the unit control system itself has closed-loop control power and temperature, etc., this value is simplified to 0.3~0.8. When the high-pressure heater group is disconnected, the unit is in full-load operation condition (i.e., the target load of the unit operation condition is 100%). λ Take 0.8; when the unit is operating at 50% load (i.e., the target load for the unit is 50%). λ Take 0.3. Based on this, λ The value can be proportional to the target load of the unit when the high-pressure heater group is disconnected; that is, when the unit is operating at 60% load. λ Take 0.4, when the unit is operating at 70% load. λ Take 0.5, when the unit is operating at 80% load. λ Take 0.6, when the unit is operating at 90% load. λ Take 0.7, and so on.

[0050] F E This represents the total steam extraction volume of the high-pressure heater group during normal unit operation, under the unit's operating conditions when the high-pressure heater group is disconnected. F E Actual measured values ​​can be used, that is, the steam extraction rates of high-pressure heaters H1, H2, and H3 during normal operation of the unit can be measured in advance under various operating conditions. F1 , F2 , F3； Then the total steam extraction rate of the high-pressure heater group is calculated, i.e.F E =F1+F2+F3 The pre-calculated measured values ​​can be obtained from the unit's operating conditions at the time of high-pressure heater disconnection. F E The value of .

[0051] S220. Based on the difference between the feedwater pump outlet pressure and the boiler-side main steam pressure, and comparing it with the set pressure difference constant, determine whether to reduce the feedwater flow rate by using the feedwater regulating valve or by reducing the feedwater pump speed itself; and cyclically adjust the opening of the feedwater regulating valve and the speed of the feedwater pump turbine to reduce the feedwater flow rate at the boiler inlet to the target feedwater value. F o At the same time, the unit automatically activates the superheater desuperheating water system to control the water temperature in real time.

[0052] The specific method is as follows:

[0053] At the moment of initiating adjustment, first determine the initial adjustment method to be used. Calculate the feedwater pump outlet pressure. P G With the main steam pressure of the unit P m The real-time difference, when the real-time difference ( P G - P m )< K At time 1, the feedwater flow rate at the boiler inlet is reduced by adjusting the opening of the feedwater regulating valve; the system issues a command to reduce the opening of the feedwater regulating valve V1, thereby reducing the feedwater flow rate at the boiler inlet. F When the real-time difference ( P G - P m )≥ K At time 1, the feedwater flow rate at the boiler inlet is reduced by adjusting the speed of the feedwater pump turbine; reducing the speed of the feedwater pump turbine, thereby reducing the feedwater flow rate at the boiler inlet. F The first pressure difference constant K The formula for calculating 1 is:

[0054] K 1= P G100 - P m100

[0055] in, P G100 This represents the measured value of the feedwater pump outlet pressure when the unit is operating normally under full load conditions; P m100This represents the measured value of the main steam pressure of the unit under normal operating conditions at full load. Among them, the first pressure difference constant... K 1 can be obtained through the following methods:

[0056] The THA operating condition from the thermodynamic characteristics book can be used, taking the difference between the feedwater pump outlet pressure and the main steam design pressure. It is recommended to use the actual feedwater pump outlet pressure from a formal THA thermal efficiency test under rated load conditions with the feedwater regulating valve fully open. P G With main steam pressure P m Difference.

[0057] Then, the outlet pressure of the water pump is calculated in real time. P G With the main steam pressure of the unit P m The real-time difference is used to determine whether to switch the adjustment method. When reducing the feedwater flow at the boiler inlet by adjusting the opening of the feedwater regulating valve, if the real-time difference ( P G - P m )< K At time 2, the system switches to reducing the feedwater flow rate at the boiler inlet by adjusting the speed of the feedwater pump turbine. At this time, the speed of the feedwater pump turbine remains constant, and the system issues a command to reduce the opening of the feedwater regulating valve V1, thereby reducing the feedwater flow rate at the boiler inlet. F When the feedwater flow rate at the boiler inlet is reduced by adjusting the turbine speed of the feedwater pump, if the real-time difference ( P G - P m )≥ K At time 3, the system switches to reducing the feedwater flow rate at the boiler inlet by adjusting the speed of the feedwater pump turbine. At this time, the opening of the feedwater regulating valve V1 remains unchanged, and the speed of the feedwater pump turbine is reduced, thereby reducing the feedwater flow rate at the boiler inlet. F Second pressure difference constant K 2 and the third pressure difference constant K The formula for calculating 3 is:

[0058] K 2= K 1- N k

[0059] K 2= K 1+ N k

[0060] in,N k This represents the redundancy of the pressure difference determined based on the unit's own heat storage capacity, with a value range of 0.5. MPa ~0.8 MPa .

[0061] S230, Recalculate the target value for water supply F o Then return to execute step S220. Water supply target value. F o The calculation formula is the same as step S210. At this time, F The value is the real-time feedwater flow rate at the boiler inlet at the current moment.

[0062] S140. Gradually reduce the feedwater flow rate at the boiler inlet and gradually lower the real-time target load. E b This enables the unit to achieve its real-time target load. E b Matching the operating conditions of the unit;

[0063] Reduce real-time target load E b The method is as follows:

[0064] Real-time comparison of the current actual load of the unit E With real-time target load E b If the current actual load E Less than or equal to the real-time target load E b Then the real-time target load will be... E b The value decreased MW. That is, the reduced real-time target load. .

[0065] in, m This indicates the steam consumption for power generation by the generator unit. m Measured values ​​can be used, that is, the main steam flow rate of the unit is measured in advance under various operating conditions during normal operation, and then the main steam flow rate and the rated power of the unit are calculated. Eo The ratio of is the unit's steam consumption for power generation under that operating condition.

[0066] After the turbine generator set is disconnected from the high-pressure heater group, the control module using the control method of this embodiment can be manually activated immediately (or the unit parameters can be detected during normal unit operation, and the corresponding control module can be automatically activated when the high-pressure heater group is disconnected to prevent the operator from being unable to operate in time). The control module first compares the unit load, confirms the unit load status, determines the unit target load adjustment and feedwater flow adjustment status, and determines the boiler feedwater flow adjustment method based on the unit main steam pressure and feedwater pump outlet pressure. On the one hand, it ensures the adjustment of feedwater flow, and on the other hand, it creates conditions for the unit desuperheating water to be put into operation, ensuring that the main steam temperature is within a controllable range.

[0067] Through the above control process, during the process where the main steam temperature of the unit experiences a rapid increase followed by a rapid decrease after the high-pressure heater group is disconnected, the main steam temperature of the unit will quickly reverse the downward trend and rise again and return to stability. At this time, the unit's load and main steam parameters can reach a stable state, so that the unit's operating state can quickly reach a new equilibrium after the high-pressure heater group is disconnected, and the control mode of the unit's normal operating state can be switched.

[0068] The control effect of the present invention will be illustrated by the following three examples.

[0069] like Figure 4 The figure shows a subcritical 600MW unit operating at rated load. The feedwater pump outlet pressure is 18.8MPa, and the main steam pressure is 16.9MPa. The deviation between the feedwater pump outlet pressure and the main steam pressure is... K 1 is 1.9 MPa. Considering the strong heat storage capacity of subcritical units, the redundancy of the pressure difference constant is... N k Take 0.5 MPa. Figure 4 During the process, the unit was disconnected at 470MW, which is less than 90% of the rated load. The main steam pressure started to rise from 11.89MPa. After using the method of this embodiment for control, the main steam temperature was basically stabilized at the initial 538℃ due to the effective effect of the desuperheating water.

[0070] like Figure 5 The figure shows the deviation between the actual feedwater pump outlet pressure and the main steam pressure of a supercritical 660MW unit under rated load conditions. K 1. Reaching 5.20 MPa, considering the weak heat storage capacity of the supercritical unit itself, the redundancy of the pressure difference constant... N k Take 0.8 MPa. Figure 5During the accident, the load was 637.81 MW, the main steam pressure was 23.20 MPa, and the main steam temperature was 558.40℃. After the high-pressure heater was disconnected, the control method of this embodiment was used. The load increased to a maximum of 675.58 MW, and the main steam pressure also increased rapidly, reaching a maximum of 25.54 MPa. The main steam temperature then rose rapidly, reaching a maximum of 567.32℃ due to the effect of the desuperheating water, and then dropped rapidly. Because the load participated in the regulation during this process, the temperature drop trend was quickly reversed, and the temperature rebounded after reaching a minimum of 540.53℃. Due to concerns about the low feedwater temperature entering the boiler, the load was further reduced. Therefore, the control mode of normal operation was switched after the system stabilized.

[0071] like Figure 6 The figure shows the deviation between the actual feedwater pump outlet pressure and the main steam pressure of a supercritical 660MW unit under rated load conditions. K 1. Reaching 3.12 MPa, considering the weak heat storage capacity of the supercritical unit itself, the redundancy of the pressure difference constant... N k Take 0.8 MPa. Figure 6 During the accident, the load was 443.93 MW, the main steam pressure was 17.01 MPa, and the main steam temperature was 566.21℃. After the high-pressure heater unit was disconnected, the control method of this embodiment was used. The load increased to a maximum of 458.75 MW, and the main steam pressure also increased rapidly, reaching a maximum of 19.81 MPa. The main steam temperature then rose rapidly, reaching a maximum of 568.27℃ due to the effect of the desuperheating water, and then dropped rapidly. Because the load participated in the regulation during this process, the temperature drop trend was quickly reversed, and the temperature began to rise again after reaching a minimum of 545.55℃. Due to concerns about the low feedwater temperature entering the boiler, the load was further reduced. Therefore, after the system stabilized, the control mode of normal operation was switched back.

[0072] In this embodiment, after the high-pressure heater is disconnected, the pressure of the superheater desuperheating water is automatically increased based on the load and main steam pressure. This prevents the superheater from malfunctioning due to excessively high steam pressure and insufficient desuperheating water flow during stagnation, which could lead to serious accidents such as steam and tube wall overheating. Simultaneously, with a constant furnace heat load, the feedwater flow rate can be quickly and orderly reduced after the high-pressure heater is disconnected, ensuring the desuperheating water operates in a closed-loop manner to control the main steam temperature and achieve a new energy balance. This maintains the unit steam within the acceptable range, preventing under-enthalpy of the main steam temperature and water hammer in the turbine, which could ultimately lead to a major unit accident and shutdown. The control process requires no operator intervention, greatly reducing the workload of monitoring and operation, significantly lowering safety hazards, and effectively and accurately ensuring the safe and stable operation of the unit and the power grid.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for rapid and stable control of a generator unit after a high-pressure heater unit accident is disconnected, characterized in that: When the high-pressure heater group of the unit is disconnected, the operating status of the unit is adjusted by rapidly reducing the boiler water intake and lowering the real-time target load of the unit, so that the load and main steam parameters of the unit can quickly reach a stable state after the high-pressure heater group is disconnected. The method for rapidly reducing the boiler's water inflow and lowering the unit's real-time target load includes the following steps: S110. The target load of the unit operating condition at the time of high-pressure heater disconnection is used as the initial real-time target load. E b ; S120. Obtain the actual operating data of the unit, determine the unit's load range based on load comparison, and simultaneously begin reducing the boiler feedwater. Both the load reduction and feedwater reduction are calculated based on the converted steam extraction rate. When the unit's current actual load... E When the real-time target load is greater than or equal to the preset load threshold, E b If the load remains unchanged, proceed to step S130; if the current actual load of the unit is less than the load threshold, proceed to step S140. S130. Gradually reduce the feedwater flow rate at the boiler inlet and monitor the actual load of the unit. E b Whether to reduce until the actual load of the unit. E b After the descent begins, proceed with step S140. S140. Gradually reduce the feedwater flow rate at the boiler inlet and gradually lower the real-time target load. E b This enables the unit to achieve its real-time target load. E b Matching the operating conditions of the unit; In steps S130 and S140, the method for gradually reducing the feedwater flow rate at the boiler inlet includes the following steps: S210. Calculate the target value of feedwater at the boiler inlet. F o ; S220, by regulating the opening of the feedwater regulating valve and the speed of the feedwater pump turbine, the feedwater flow rate at the boiler inlet is reduced to the target feedwater value. F o ; S230, Recalculate the target value for water supply F o Return to step S220.

2. The control method for rapid stabilization of the unit after the high-pressure heater unit accident is disconnected according to claim 1, characterized in that, In steps S210 and S230, the target value of water supply F o The calculation formula is: F o =F-λF E in, F This indicates the real-time feedwater flow rate at the boiler inlet; λ This represents the conversion factor for the steam extraction capacity of the high-pressure heater group. λ The value range is 0.3 to 0.8; F E This represents the total steam extraction volume of the high-pressure heater group during normal unit operation, under the unit's operating conditions when the high-pressure heater group is disconnected.

3. The control method for rapid stabilization of the unit after the high-pressure heater unit accident is disconnected according to claim 1, characterized in that: The opening of the feedwater regulating valve and the speed of the feedwater pump turbine are cyclically adjusted to reduce the feedwater flow rate at the boiler inlet to the target value. F o The method is as follows: Calculate the outlet pressure of the water supply pump P G With the main steam pressure of the unit P m The real-time difference, when the real-time difference is less than the preset first pressure difference constant. K At time 1, the feedwater flow rate at the boiler inlet is reduced by adjusting the opening of the feedwater regulating valve; When the real-time difference is greater than or equal to the preset first pressure difference constant K At time 1, the feedwater flow rate at the boiler inlet is reduced by adjusting the turbine speed of the feedwater pump; Then, the outlet pressure of the water pump is calculated in real time. P G With the main steam pressure of the unit P m The real-time difference, when the feedwater flow rate at the boiler inlet is reduced by adjusting the opening of the feedwater regulating valve, if the real-time difference is less than the preset second pressure difference constant. K At time 2, the system switches to reducing the feedwater flow rate at the boiler inlet by adjusting the speed of the feedwater pump turbine. When reducing the feedwater flow rate at the boiler inlet by adjusting the speed of the feedwater pump turbine, if the real-time difference is greater than or equal to the preset third pressure difference constant... K At time 3, the system switches to reducing the feedwater flow rate at the boiler inlet by adjusting the turbine speed of the feedwater pump.

4. The control method for rapid stabilization of the unit after the high-pressure heater unit accident is disconnected according to claim 1, characterized in that: Reduce real-time target load E b The method is as follows: Real-time comparison of the current actual load of the unit E With real-time target load E b If the current actual load E Less than or equal to the real-time target load E b Then the real-time target load will be... E b The value decreased megawatts; in, λ This represents the conversion factor for the steam extraction capacity of the high-pressure heater group; F E This represents the total steam extraction volume of the high-pressure heater group when the unit is operating normally, under the condition of the unit being disconnected from the high-pressure heater group; m This indicates the steam consumption for power generation by the generator unit.

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