Control Method for Cold State Preheating Start-up of Steam Turbine in Gas-steam Combined Cycle Unit

Abstract

The present application proposes a cold preheating start control method for a steam turbine in a gas-steam combined cycle unit, which is applied to a coaxial gas-steam combined cycle unit and includes: issuing action instructions to each valve of the steam turbine; confirming the steam quality, and shielding the Z2 criterion during the confirmation process; determining the warm-up pipe state, and shielding the verification of the Z4 criterion and the fully open state of the ESV valve; verifying the steam inlet volume of the steam turbine; verifying the shaft temperature, steam flow rate, superheat degree, and X1 criterion; controlling the opening of the drain valves in front of the high-pressure control valve and the medium-pressure control valve; releasing the steam quality confirmation button, and verifying various parameters of the steam turbine, while shielding the verification of the Z2 criterion, X6 criterion, and the fully open state of the ESV valve; setting the speed set value in the steam turbine controller to the warm-up speed; starting to calculate the warm-up time, and reaching the preset speed value in the water washing mode; engaging the SSS clutch until the sequence control start is completed.

Description

Technical Field

[0001] This application relates to the field of intelligent control of gas - steam combined cycle units, and particularly to a cold - state pre - warming start - up control method for a steam turbine of a gas - steam combined cycle unit. Background Art

[0002] The coaxial gas - steam combined cycle unit first applied the cold - state pre - warming technology, adding two pre - warming steam pipelines on the steam turbine side. The pre - warming steam pipelines act on the high - pressure main steam pipeline of the high - pressure cylinder of the steam turbine and on the medium - pressure cylinder side respectively. When starting the steam turbine for turning and synchronizing to the grid, it can effectively reduce the unit start - up time and achieve the goal of energy conservation and efficiency improvement.

[0003] However, how to achieve the automatic start - up of the steam turbine of the gas - steam combined cycle unit based on the cold - state pre - warming technology has become an urgent problem to be solved at present. Summary of the Invention

[0004] To solve the above problems, this application provides a cold - state pre - warming start - up control method for a steam turbine of a gas - steam combined cycle unit.

[0005] According to one aspect of this application, there is provided a cold - state pre - warming start - up control method for a steam turbine of a gas - steam combined cycle unit. The method is applied to a coaxial gas - steam combined cycle unit, and high - pressure pre - warming steam pipelines and medium - pressure pre - warming steam pipelines are added on the steam turbine side of the coaxial gas - steam combined cycle unit. Among them, the high - pressure pre - warming steam pipeline is connected to the main steam pipeline of the high - pressure cylinder, the medium - pressure pre - warming steam pipeline is directly connected to the medium - pressure cylinder side, and pre - warming valve groups are installed on both the high - pressure pre - warming steam pipeline and the medium - pressure pre - warming steam pipeline; the method includes:

[0006] Issuing action instructions to each valve of the steam turbine;

[0007] Confirming the steam quality, and shielding the Z2 criterion during the confirmation process;

[0008] Determining the warm - up pipe state, and shielding the verification of the Z4 criterion and the fully - open state of the ESV valve;

[0009] Verifying the steam inlet volume of the steam turbine;

[0010] Verifying the shaft temperature, steam flow rate, superheat degree, and X1 criterion;

[0011] Controlling the opening of the drain valves in front of the high - pressure control valve and the medium - pressure control valve;

[0012] Releasing the steam quality confirmation button, and verifying various parameters of the steam turbine, while shielding the verification of the Z2 criterion, X6 criterion, and the fully - open state of the ESV valve;

[0013] Set the speed setpoint in the steam turbine controller to the warm-up speed;

[0014] Start the calculation of the warm-up time and reach the preset speed value in the water wash mode;

[0015] Engage the SSS clutch until the sequence control startup is completed.

[0016] In some embodiments of the present application, issuing action instructions to the valves of the steam turbine includes:

[0017] Issue closing instructions to the high-pressure main steam valve, intermediate-pressure main steam valve, low-pressure main steam valve, high-pressure control valve, intermediate-pressure control valve, low-pressure control valve, and high-pressure exhaust check valve;

[0018] Issue an instruction to engage the steam turbine pressure controller;

[0019] Issue an instruction to engage the drain sub-loop;

[0020] Issue opening instructions to the drain valve in front of the high-pressure control valve, the drain valve in front of the intermediate-pressure control valve, and the low-pressure cylinder spray isolation valve;

[0021] Issue an opening instruction to the drain valve in front of the intermediate-pressure main steam valve.

[0022] Among them, the verification of the steam inlet volume of the steam turbine includes:

[0023] Compare the steam inlet setpoint of the steam turbine with a preset steam inlet threshold, and compare the TAB value of the steam turbine with a preset first TAB threshold;

[0024] In response to the steam inlet setpoint of the steam turbine being greater than the steam inlet threshold and the TAB value of the steam turbine being greater than the first TAB threshold, perform the steps of verifying the bearing temperature, steam flow rate, and superheat degree.

[0025] In some embodiments of the present application, the verification of the bearing temperature, steam flow rate, superheat degree, and X1 criterion includes:

[0026] Compare the high-pressure rotor bearing temperature with a preset bearing temperature threshold;

[0027] Compare the steam flow rate with a preset flow rate threshold;

[0028] Compare the main steam superheat degree with a preset superheat degree threshold;

[0029] Verify the X1 criterion;

[0030] In response to the high-pressure rotor shaft temperature being greater than the shaft temperature threshold, the steam flow rate being greater than the flow rate threshold, the superheat degree being greater than the superheat degree threshold, and the X1 criterion being satisfied, without waiting for the ESV valve to be fully open, directly execute the step of controlling the opening of the drain valve before the high-pressure control valve and the drain valve before the intermediate-pressure control valve.

[0031] In some embodiments of the present application, controlling the opening of the drain valve before the high-pressure control valve and the drain valve before the intermediate-pressure control valve includes:

[0032] Start the static frequency conversion starting device of the gas turbine, and issue an instruction to open the drain valve before the high-pressure control valve and the drain valve before the intermediate-pressure control valve when the gas turbine speed is greater than the preset gas turbine speed.

[0033] As a possible implementation, setting the speed set value in the steam turbine controller to the warm-up speed includes:

[0034] Set the speed set value in the steam turbine controller to the warm-up speed, and increase the speed of the steam turbine at a first rising rate until the speed of the steam turbine reaches the warm-up speed, and reset the steam quality confirmation button; wherein, the first rising rate is less than the rising rate of the speed during the cold start of the steam turbine.

[0035] In some embodiments of the present application, starting to calculate the warm-up time and reaching a preset speed value in the water washing mode includes:

[0036] Start to calculate the warm-up time, wherein the speed of the steam turbine satisfies the preset speed value in the water washing mode, and the verification of the Z2 criterion, Z4 criterion, X6 criterion, and full opening of the ESV valve is shielded.

[0037] In some embodiments of the present application, the SSS clutch is engaged until the sequence control start is completed, including:

[0038] The SSS clutch is engaged, the pre-warming intermediate-pressure stop valve and the pre-warming high-pressure stop valve are controlled to close, and the high-pressure exhaust ventilation valve is controlled to close, and the speed of the steam turbine is increased to a preset speed threshold at a second rising rate; wherein, the second rising rate is less than the rising rate of the speed during the cold start of the steam turbine;

[0039] Reset the rated speed release button on the screen;

[0040] Compare the TAB value of the steam turbine with a preset second TAB threshold;

[0041] In response to the TAB value of the steam turbine being greater than the second TAB threshold, continue to engage the SSS clutch;

[0042] It is the initial pressure controller for the steam turbine control start-up to complete the sequential control start-up of the steam turbine.

[0043] In some other embodiments of the present application, the method further includes:

[0044] Extend the holding duration after the gas turbine reaches the preset rotational speed value in the water washing mode.

[0045] According to the technical solution of the present application, by shielding the verification of the Z2 criterion, Z4 criterion, X6 criterion, and full opening of the ESV valve during the sequential control start-up of the steam turbine, the automatic cold pre-warming start-up of the steam turbine in the gas-steam combined cycle unit is realized. It can not only effectively reduce the unit start-up time, but also achieve the goal of energy conservation and efficiency improvement, and can also avoid problems such as start-up failure caused by issues such as the triggering of the protection logic during the start-up process.

[0046] The additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present application. Brief Description of the Drawings

[0047] The above-mentioned and / or additional aspects and advantages of the present application will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0048] Figure 1 It is a flowchart of a cold pre-warming start-up control method for a steam turbine in a gas-steam combined cycle unit provided by an embodiment of the present application;

[0049] Figure 2 It is a schematic structural diagram of the cold pre-warming of a steam turbine in a coaxial gas-steam combined cycle unit in an embodiment of the present application;

[0050] Figure 3 It is a schematic diagram of the cold pre-warming start-up process of a steam turbine in a gas-steam combined cycle unit in an embodiment of the present application;

[0051] Figure 4 It is a schematic diagram of another cold pre-warming start-up process of a steam turbine in a gas-steam combined cycle unit in an embodiment of the present application;

[0052] Figure 5 It is a schematic diagram of yet another cold pre-warming start-up process of a steam turbine in a gas-steam combined cycle unit in an embodiment of the present application. Detailed Description of the Embodiments

[0053] The embodiments of the present application will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application and should not be construed as a limitation of the present application.

[0054] It should be noted that the cold pre-warming technology is applied to the coaxial gas-steam combined cycle unit for the first time. Two pre-warming steam pipelines are added on the steam turbine side. The pre-warming steam pipelines act on the high-pressure main steam pipeline of the high-pressure cylinder of the steam turbine and on the side of the intermediate-pressure cylinder respectively. When starting the steam turbine for turning and synchronizing, the start-up time of the unit can be effectively reduced, achieving the goal of energy conservation and efficiency improvement.

[0055] However, how to realize the automatic start-up of the steam turbine of the gas-steam combined cycle unit based on the cold pre-warming technology has become an urgent problem to be solved at present.

[0056] To solve the above problems, the present application provides a cold pre-warming start-up control method for the steam turbine of a gas-steam combined cycle unit.

[0057] Figure 1 The figure is a flow chart of a cold pre-warming start-up control method for the steam turbine of a gas-steam combined cycle unit provided by an embodiment of the present application. It should be noted that the cold pre-warming start-up control method for the steam turbine of the gas-steam combined cycle unit in the embodiment of the present application is applied to a coaxial gas-steam combined cycle unit, and a high-pressure pre-warming steam pipeline and an intermediate-pressure pre-warming steam pipeline are added on the steam turbine side of the coaxial gas-steam combined cycle unit. Among them, the high-pressure pre-warming steam pipeline is connected to the main steam pipeline of the high-pressure cylinder, the intermediate-pressure pre-warming steam pipeline is directly communicated with the side of the intermediate-pressure cylinder, and pre-warming valve groups are installed on both the high-pressure pre-warming steam pipeline and the intermediate-pressure pre-warming steam pipeline. As Figure 2 shown, a high-pressure pre-warming steam pipeline 201 and an intermediate-pressure pre-warming steam pipeline 202 are added on the steam turbine side of the coaxial gas-steam combined cycle unit. Among them, the high-pressure pre-warming steam pipeline 201 is connected to the main steam pipeline of the high-pressure cylinder, the intermediate-pressure pre-warming steam pipeline 202 is directly communicated with the side of the intermediate-pressure cylinder, and pre-warming valve groups are installed on both the high-pressure pre-warming steam pipeline 201 and the intermediate-pressure pre-warming steam pipeline 202. Two pneumatic shut-off valves are installed on the high-pressure pre-warming steam pipeline 201, and one pneumatic shut-off valve and one start-up shut-off regulating valve are installed on the intermediate-pressure pre-warming steam pipeline 202. As Figure 1 shown, the test method includes the following steps:

[0058] Step 101, issue action instructions to each valve of the steam turbine.

[0059] In some embodiments of the present application, during the sequence control of the steam turbine start-up, there is no need to issue a start-up load limit input instruction. Just wait until the speed is greater than the preset value, and then execute the step of issuing action instructions to each valve of the steam turbine. For example, just wait until the speed is greater than 858 r / min, and then execute the step of issuing action instructions to each valve of the steam turbine.

[0060] Among them, the process of issuing action instructions to each valve of the steam turbine may include the following steps:

[0061] Step 101-1: Send a closing command to the high-pressure main steam valve, intermediate-pressure main steam valve, low-pressure main steam valve, high-pressure control valve, intermediate-pressure control valve, low-pressure control valve, and high-pressure exhaust non-return valve.

[0062] In the embodiment of the present application, a closing command is sent to the high-pressure main steam valve, intermediate-pressure main steam valve, low-pressure main steam valve, high-pressure control valve, intermediate-pressure control valve, low-pressure control valve, and high-pressure exhaust non-return valve, and after they are all in the ready state, Step 101-2 is executed.

[0063] Step 101-2: Send a command to activate the turbine pressure controller.

[0064] In some embodiments of the present application, a command to activate the turbine pressure controller is sent, and after all the parameters of the turbine are in their respective pressure and temperature modes and the rotational speed is greater than 858 r / min, Step 101-3 is executed.

[0065] Step 101-3: Send a command to activate the drain sub-loop.

[0066] That is to say, after sending a command to activate the drain sub-loop and the drain sub-loop is in the ready state, Step 101-4 is executed.

[0067] Step 101-4: Send an opening command to the drain valve before the high-pressure control valve, the drain valve before the intermediate-pressure control valve, and the low-pressure cylinder spray isolation valve.

[0068] In some embodiments of the present application, an opening command is sent to the drain valve before the high-pressure control valve, the drain valve before the intermediate-pressure control valve, and the low-pressure cylinder spray isolation valve, and after waiting for a period of time and they are all in the fully open state, Step 101-5 is executed. For example, after sending the opening command, when the drain valve before the high-pressure control valve, the drain valve before the intermediate-pressure control valve, and the low-pressure cylinder spray isolation valve are all in the fully open state within 90 s, Step 101-5 is executed.

[0069] Step 101-5: Send an opening command to the drain valve before the intermediate-pressure main steam valve.

[0070] In some embodiments of the present application, an opening command is sent to the drain valve before the intermediate-pressure main steam valve, and after waiting for 90 s and the drain valve before the intermediate-pressure main steam valve is in the fully open state, or when the turbine startup device control task TAB meets more than 62%, the subsequent steps are executed.

[0071] Step 102: Confirm the steam quality, and shield the Z2 criterion during the confirmation process.

[0072] Based on the sample before the start-up sequence control, it is found that since the medium-pressure preheating steam pipe acts directly on the medium-pressure cylinder, the corresponding thermal stress X and Z criteria cannot be triggered during the start-up process. Otherwise, it will directly wait and cannot continue the start-up test. Therefore, the thermal stress Z2 criterion needs to be shielded during the determination of steam quality.

[0073] It can be understood that only when the steam quality is qualified can the steam turbine operate stably and safely, protect the blades at all levels of the steam turbine, avoid changes in the blade profile of the steam turbine, and also avoid problems such as a decrease in the efficiency of the steam turbine, an increase in axial thrust, and an increase in vibration.

[0074] In some embodiments of the present application, the process of confirming the steam quality may include: verifying the thermal stress Z1 criterion and the thermal stress X1 criterion, or verifying the opening of the high-pressure control valve; verifying the wall temperature, and there is no need to verify the thermal stress Z2 criterion, the X2 criterion, and the fully open state of the ESV valve. As an example, if both the thermal stress Z1 criterion and the thermal stress X1 criterion are satisfied, or the opening of the high-pressure control valve is more than 50%, and the wall temperature is less than 150 °C, there is no need to further confirm whether the thermal stress Z2 criterion and the X2 criterion are satisfied, nor to wait for the fully open state of the ESV valve, and directly continue to execute step 103.

[0075] Step 103: Determine the warm-up state and shield the verification of the Z4 criterion and the fully open state of the ESV valve.

[0076] It can be understood that normal warm-up temperature and pressure can prevent problems such as large vibration of the steam turbine and pipeline fracture. Among them, the determination of the warm-up state is equivalent to the verification of the warm-up temperature and pressure. If both the warm-up temperature and pressure meet the regulations, the warm-up state is normal. That is to say, if the warm-up state is normal, there is no need to confirm whether the thermal stress Z4 criterion is satisfied, nor to confirm whether the ESV valve is in the fully open state, and directly continue to execute step 104.

[0077] Step 104: Verify the steam inlet volume of the steam turbine.

[0078] It can be understood that the size of the steam inlet volume of the steam turbine is directly related to the stable start-up of the steam turbine. By verifying the steam inlet volume of the steam turbine, the stable start-up of the steam turbine can be ensured, and it can also lay a foundation for the increase in the speed of the steam turbine and the constant-speed impulse rotation of the steam turbine.

[0079] In some embodiments of the present application, the implementation process of verifying the steam inlet quantity of a steam turbine may include: comparing the steam inlet set value of the steam turbine with a preset steam inlet threshold, and comparing the TAB value of the steam turbine with a preset first TAB threshold; in response to the steam inlet set value of the steam turbine being greater than the steam inlet threshold and the TAB value of the steam turbine being greater than the first TAB threshold, performing step 105 of verifying the bearing temperature, steam flow rate, and superheat degree. For example, if the approximate set value of the steam turbine is greater than 98% and the TAB value of the steam turbine is greater than 62%, step 105 can be continued.

[0080] That is to say, if the steam inlet set value of the steam turbine is greater than the steam inlet threshold and the TAB value of the steam turbine is greater than the first TAB threshold, there is no need to wait for all ESV valves to be fully open within a preset time, and step 105 can be directly executed.

[0081] Step 105: Verify the bearing temperature, steam flow rate, superheat degree, and X1 criterion.

[0082] In some embodiments of the present application, this step may include: comparing the high-pressure rotor bearing temperature with a preset bearing temperature threshold; comparing the steam flow rate with a preset flow rate threshold; comparing the main steam superheat degree with a preset superheat degree threshold; verifying the X1 criterion; in response to the high-pressure rotor bearing temperature being greater than the bearing temperature threshold, the steam flow rate being greater than the flow rate threshold, the superheat degree being greater than the superheat degree threshold, and the X1 criterion being satisfied, there is no need to wait for the ESV valve to be fully open, and directly execute the step of controlling the opening of the drain valve before the high-pressure control valve and the drain valve before the intermediate-pressure control valve. For example, if the preset bearing temperature threshold is 200 °C for comparison and the preset flow rate threshold is 15%, in response to the high-pressure rotor bearing temperature being greater than 200 °C, the steam flow rate being greater than 15%, and the superheat degree X1 criterion being satisfied at the same time, there is no need to wait for the ESV valve to be fully open, and step 106 can be directly executed.

[0083] Step 106: Control the opening of the drain valve before the high-pressure control valve and the drain valve before the intermediate-pressure control valve.

[0084] In order to avoid the problem of temperature rise of the high-pressure control valve and the intermediate-pressure control valve during startup, the drain valve before the high-pressure control valve and the drain valve before the intermediate-pressure control valve can be opened in time to cool down the temperature around the high-pressure control valve and the intermediate-pressure control valve.

[0085] In some embodiments of the present application, start the static frequency conversion starting device of the gas turbine. Among them, the gas turbine startup mode is the water washing mode. When the gas turbine speed reaches the preset gas turbine speed, an instruction to open the drain valve before the high-pressure control valve and the drain valve before the intermediate-pressure control valve is issued. That is to say, start the static frequency conversion device of the gas turbine. When the gas turbine speed is greater than 780 r / min, open the drain valve before the high-pressure control valve and the drain valve before the intermediate-pressure control valve.

[0086] Step 107: Release the steam quality confirmation button, calibrate various parameters of the steam turbine, and simultaneously shield the calibration of the Z2 criterion, X6 criterion, and the fully open state of the ESV valve.

[0087] Step 108: Set the speed setpoint in the turbine controller to the warm-up speed.

[0088] In some embodiments of the present application, this step includes: setting the speed setpoint in the turbine controller to the warm-up speed, and increasing the speed of the steam turbine at a first rising rate until the speed of the steam turbine reaches the warm-up speed, and resetting the steam quality confirmation button. Among them, the first rising rate is less than the rising rate of the speed during the cold start of the steam turbine. That is to say, by reducing the rising rate of the speed, the stability of the start-up process can be further improved.

[0089] Step 109: Start calculating the warm-up time, and reach the preset speed value in the water wash mode.

[0090] In some embodiments of the present application, the process of starting to calculate the warm-up time includes: verifying whether the speed of the steam turbine meets the preset speed value in the water wash mode; verifying the valve limits of the high-pressure control valve, intermediate-pressure control valve, and low-pressure control valve; verifying the relevant thermal stress X criterion and Z criterion; verifying the high-pressure main steam flow; verifying the high-pressure cylinder temperature difference; and simultaneously shielding the calibration of the thermal stress Z2 criterion, Z4 criterion, and X6 criterion, and also shielding the verification of all ESV valves being fully open.

[0091] As an example, if within the corresponding time range, the speed value of the steam turbine reaches 780 r / min, and the valve limits of the high-pressure control valve, intermediate-pressure control valve, and low-pressure control valve are all greater than 105%, and the relevant thermal stress X criterion and Z criterion are both met, and the calibration of the thermal stress Z2 criterion, Z4 criterion, and X6 criterion is shielded, and the high-pressure main steam flow is greater than 15%, and the high-pressure cylinder temperature difference meets the requirements, then without waiting for the state of all ESV valves being fully open, directly proceed to the index step 110.

[0092] Step 110: Engage the SSS clutch until the sequence start-up is completed.

[0093] In some embodiments of the present application, step 110 may include the following steps:

[0094] Step 110-1: Engage the SSS clutch, control the pre-warming intermediate-pressure stop valve and pre-warming high-pressure stop valve to close, and control the high-pressure exhaust ventilation valve to close, and increase the speed of the steam turbine to a preset speed threshold at a second rising rate; where the second rising rate is less than the rising rate of the speed during the cold start of the steam turbine.

[0095] As an example, if the prewarming medium-pressure stop valve and the prewarming high-pressure stop valve are both closed, and the high-pressure exhaust ventilation valve is also closed, and the rotational speed of the steam turbine rises to above 2850 r / min at the second rising rate, then step 110-2 is continued to be executed.

[0096] Step 110-2: Reset the rated speed release button on the screen.

[0097] In the embodiment of the present application, the rated speed release button on the screen is reset, and after the drain valves in front of the high-pressure control valve, the medium-pressure main steam valve, and the medium-pressure control valve are all closed, step 110-3 is executed.

[0098] Step 110-3: Compare the TAB value of the steam turbine with a preset second TAB threshold.

[0099] For example, the second TAB threshold can be 99%, that is, the TAB value of the steam turbine is compared with 99%.

[0100] Step 110-4: In response to the TAB value of the steam turbine being greater than the second TAB threshold, continue to engage the SSS clutch.

[0101] In some embodiments of the present application, if the TAB value of the steam turbine is greater than the second TAB threshold, then continue to engage the SSS clutch. If the rotational speed of the steam turbine reaches above 2850 r / min, and the high bypass valve is less than 5%, the high-pressure main steam flow rate is greater than 20%, and the high-pressure inlet blade pressure is greater than 2.5 Mpa, then step 110-5 is continued to be executed.

[0102] Step 110-5: Control the start-up initial pressure controller for the steam turbine to complete the start-up sequence control of the steam turbine.

[0103] In some embodiments of the present application, the entire start-up control method may further include: extending the holding duration after the gas turbine reaches the preset rotational speed in the water washing mode. In this way, it is possible to wait for the steam turbine to reach the preset rotational speed and then successfully engage.

[0104] Next, through the schematic diagram during the start-up process, the cold prewarming start-up control method of the steam turbine of the gas-steam combined cycle unit in the embodiment of the present application will be verified.

[0105] Figure 3 It is a schematic diagram of the cold prewarming start-up process of the steam turbine of the gas-steam combined cycle unit in the embodiment of the present application. As Figure 3 shown, during the entire cold prewarming start-up process of the unit, the signals of the thermal stress Z2 criterion, Z4 criterion, and X6 criterion are not triggered, and the digital input signals are all 0. At the same time, if the rotational speed of the steam turbine remains as above, it proves that the Z2 criterion, Z4 criterion, and X6 criterion are successfully shielded during this start-up process, and the normal start-up of the steam turbine is ensured.

[0106] Figure 4 This is a schematic diagram of the cold preheating start-up process of the steam turbine in another gas-steam combined cycle unit in the embodiment of the present application. As Figure 4 shown, during the entire cold preheating start-up process of the unit, the signal that all ESV valves are in the fully open state is not triggered, and the digital input signal is 0. At the same time, the speed of the steam turbine still rises. Therefore, it shows that this process successfully shields the verification that all ESV valves are in the fully open state and ensures the normal start-up of the steam turbine.

[0107] Figure 5 This is a schematic diagram of the cold preheating start-up process of the steam turbine in yet another gas-steam combined cycle unit in the embodiment of the present application. As Figure 5 shown, during the entire cold preheating start-up process of the unit, after the speed of the gas turbine reaches the preset value of 780 r / min, the static frequency converter start-up device SFC signal successfully makes the speed of the steam turbine reach the preset value of 780 r / min and successfully meshes with the gas turbine within 30 minutes. That is to say, by extending the time of the fifth step of the gas turbine start-up sequence control in the preheating mode, the SFC can smoothly drive the speed of the steam turbine to the preset value and successfully mesh with the gas turbine.

[0108] According to the cold preheating start-up control method of the steam turbine in the gas-steam combined cycle unit of the embodiment of the present application, by shielding the verification of the Z2 criterion, Z4 criterion, X6 criterion, and the full opening of the ESV valve during the sequence control start-up process of the steam turbine, the automatic cold preheating start-up of the steam turbine in the gas-steam combined cycle unit is realized. It can not only effectively reduce the unit start-up time, but also achieve the goal of energy conservation and efficiency improvement, and can also avoid problems such as start-up failure caused by the triggering of protection logic during the start-up process.

[0109] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0110] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features indicated. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0111] Any process or method description represented in a flowchart or described otherwise herein can be understood to represent a module, segment, or portion of code including one or more executable instructions for implementing a customized logical function or process. The scope of the preferred embodiments of this application includes additional implementations where functions may be executed not in the order shown or discussed, including in a substantially simultaneous manner according to the functions involved or in a reverse order, which should be understood by those skilled in the art to which the embodiments of this application pertain.

[0112] The logic and / or steps represented in a flowchart or described otherwise herein, for example, can be considered a sequenced list of executable instructions for implementing a logical function and can be specifically implemented in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can even be paper or other suitable media on which the program can be printed, as the program can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpretation, or other appropriate processing as necessary, and then storing it in a computer memory.

[0113] It should be understood that each part of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, any one of the following techniques known in the art or a combination thereof can be used: discrete logic circuits with logic gate circuits for implementing logical functions on data signals, application-specific integrated circuits with suitable combinational logic gate circuits, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0114] Those of ordinary skill in the art can understand that all or part of the steps carried by the method of implementing the above embodiments can be completed by instructing relevant hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiments.

[0115] In addition, in each embodiment of the present application, each functional unit can be integrated into a processing module, or each unit can exist physically alone, or two or more units can be integrated into one module. The above integrated module can be implemented in the form of hardware or in the form of a software functional module. When the above integrated module is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0116] The above-mentioned storage medium can be a read-only memory, a magnetic disk, an optical disc, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A control method for cold pre-warming start-up of a steam turbine in a gas-steam combined cycle unit, characterized in that, the method is applied to a coaxial gas-steam combined cycle unit, and a high-pressure pre-warming steam pipeline and a medium-pressure pre-warming steam pipeline are added on the steam turbine side of the coaxial gas-steam combined cycle unit. Among them, the high-pressure pre-warming steam pipeline is connected to the main steam pipeline of the high-pressure cylinder, the medium-pressure pre-warming steam pipeline is directly connected to the medium-pressure cylinder side, and pre-warming valve groups are installed on both the high-pressure pre-warming steam pipeline and the medium-pressure pre-warming steam pipeline; it includes: Issuing action instructions to each valve of the steam turbine; Confirming the steam quality, and shielding the Z2 criterion during the confirmation process; Determining the pipe warming state, and shielding the verification of the Z4 criterion and the fully open state of the ESV valve; Verifying the steam inlet volume of the steam turbine; Verifying the shaft temperature, steam flow, superheat degree and X1 criterion; Controlling the opening of the drain valve before the high-pressure control valve and the drain valve before the medium-pressure control valve; Releasing the steam quality confirmation button, and verifying various parameters of the steam turbine, while shielding the verification of the Z2 criterion, X6 criterion and the fully open state of the ESV valve; Setting the speed set value in the turbine controller to the warm-up speed; Starting to calculate the warm-up time, and reaching the preset speed value in the water washing mode; The SSS clutch engages until the sequence control start is completed.

2. The method according to claim 1, characterized in that, the issuing action instructions to each valve of the steam turbine includes: Issuing closing instructions to the high-pressure main steam valve, medium-pressure main steam valve, low-pressure main steam valve, high-pressure control valve, medium-pressure control valve, low-pressure control valve, and high-pressure exhaust check valve; Issuing an instruction to put into the turbine pressure controller; Issuing an instruction to put into the drain sub-loop; Issuing opening instructions to the drain valve before the high-pressure control valve, the drain valve before the medium-pressure control valve, and the low-pressure cylinder spray isolation valve; Issuing an opening instruction to the drain valve before the medium-pressure main steam valve.

3. The method according to claim 1, characterized in that, the verifying the steam inlet volume of the steam turbine includes: Comparing the steam inlet set value of the steam turbine with a preset steam inlet threshold value, and comparing the TAB value of the steam turbine with a preset first TAB threshold value; In response to the steam inlet set value of the steam turbine being greater than the steam inlet threshold value, and the TAB value of the steam turbine being greater than the first TAB threshold value, performing the step of verifying the shaft temperature, steam flow and superheat degree.

4. The method according to claim 1, characterized in that, the verifying the shaft temperature, steam flow, superheat degree and X1 criterion includes: Comparing the high-pressure rotor shaft temperature with a preset shaft temperature threshold value; Comparing the steam flow with a preset flow threshold value; Comparing the main steam superheat degree with a preset superheat degree threshold value; Verifying the X1 criterion; In response to the high-pressure rotor shaft temperature being greater than the shaft temperature threshold value, the steam flow being greater than the flow threshold value, the superheat degree being greater than the superheat degree threshold value, and the X1 criterion being satisfied, without waiting for the ESV valve to be in the fully open state, directly performing the step of controlling the opening of the drain valve before the high-pressure control valve and the drain valve before the medium-pressure control valve.

5. The method according to claim 1, characterized in that, Control the opening of the drain valve before the high-pressure control valve and the drain valve before the intermediate-pressure control valve, including: Start the static frequency converter starting device of the gas turbine, and issue an instruction to open the drain valve before the high-pressure control valve and the drain valve before the intermediate-pressure control valve when the gas turbine speed is greater than the preset gas turbine speed.

6. The method according to claim 1, wherein, The step of setting the speed set value in the steam turbine controller to the warm-up speed includes: Set the speed set value in the steam turbine controller to the warm-up speed, and increase the speed of the steam turbine at a first rising rate until the speed of the steam turbine reaches the warm-up speed, and reset the steam quality confirmation button; wherein, the first rising rate is less than the rising rate of the speed during the cold start of the steam turbine.

7. The method according to claim 1, wherein, The step of starting to calculate the warm-up time and reaching a preset speed value in the water washing mode includes: Start to calculate the warm-up time, wherein the speed of the steam turbine meets the preset speed value in the water washing mode, and the Z2 criterion, Z4 criterion, X6 criterion, and the verification of the full opening of the ESV valve are shielded.

8. The method according to claim 1, wherein, The step of engaging the SSS clutch until the sequence control start is completed includes: Engage the SSS clutch, control the pre-warming intermediate-pressure stop valve and the pre-warming high-pressure stop valve to close, and control the high-pressure exhaust ventilation valve to close, and increase the speed of the steam turbine to a preset speed threshold at a second rising rate; wherein, the second rising rate is less than the rising rate of the speed during the cold start of the steam turbine; Reset the rated speed release button on the screen; Compare the TAB value of the steam turbine with a preset second TAB threshold; In response to the TAB value of the steam turbine being greater than the second TAB threshold, continue to engage the SSS clutch; Control the start-up initial pressure controller for the steam turbine to complete the start-up sequence control of the steam turbine.

9. The method according to any one of claims 1-8, wherein, It further includes: Extend the holding duration after the gas turbine reaches the preset speed value in the water washing mode.

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