Shutdown control system and method for gas-steam combined cycle unit

Abstract

The invention discloses a shutdown control system and method for a gas-steam combined cycle unit. The system comprises a steam turbine shutdown breakpoint unit and a gas turbine shutdown breakpoint unit which are connected with each other. The steam turbine shutdown breakpoint unit is used for executing a steam turbine shutdown control mode when steam turbine shutdown control is completed, and the gas turbine shutdown breakpoint unit is used for executing a gas turbine shutdown control mode when steam turbine shutdown control is completed. The method comprises two steam turbine shutdown control modes and two gas turbine shutdown control modes. According to the method, the problem that a shutdown control program of an original DCS (Distributed Control System) does not meet the requirements of field practical application in the installation and debugging process of a conventional unit is solved, and an APS shutdown control strategy is reconstructed to realize safe and stable shutdown of the unit.

Description

Technical Field

[0001] The invention belongs to the technical field of intelligent control of thermal power plants, and in particular relates to a shutdown control system and method for a gas-steam combined cycle unit. Background Art

[0002] The shutdown control technology of gas-steam combined cycle units is a key process to ensure the correct and safe shutdown of the unit. Shutdown control technology involves multiple stages and multiple control strategies, and needs to comprehensively consider safety, economy and the operating characteristics of the equipment. Specifically, it includes: modular design ideas, step-by-step phasing, automatic start-stop control system application, APS structure and function design, full water supply and combustion control, APS and other system interfaces, protection and interlocking logic, design framework and preparation.

[0003] In general, the shutdown control technology of gas-steam combined cycle units requires the comprehensive use of multiple control strategies and systems, from the realization of modular design, step-by-step control, to the application of automatic start-stop control system, and the whole process of water supply and combustion control. The protection and interlocking logic during the shutdown process, the interface between APS and other systems, and the related design framework and preparation are all key factors to ensure the smooth and safe shutdown process. Summary of the invention

[0004] The purpose of the present invention is to provide a gas-steam combined cycle unit shutdown control system and method to solve the problem that the shutdown control program of the original DCS system does not meet the actual application requirements during the installation and commissioning of conventional units. The APS shutdown control strategy will be rebuilt to achieve safe and stable shutdown of the unit.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: A gas-steam combined cycle unit shutdown control system, comprising a steam turbine shutdown breakpoint unit and a gas turbine shutdown breakpoint unit connected to each other; The steam turbine shutdown breakpoint unit is used to execute the steam turbine shutdown control mode. When the steam turbine shutdown control is completed, the gas turbine shutdown breakpoint unit is used to execute the gas turbine shutdown control mode.

[0006] A further improvement of the present invention is that the turbine shutdown breakpoint unit includes a turbine shutdown permission condition unit, a gas turbine load reduction to 100MW unit, a steam turbine high and medium pressure pressure control and low pressure main steam unit, a gas turbine slow load reduction unit and a turbine shutdown unit; The steam turbine shutdown permission condition unit is connected to the gas turbine load reduction to 100MW unit, the gas turbine load reduction to 100MW unit is respectively connected to the pressure control and low-pressure main steam unit of the steam turbine reducing high and medium pressure and the gas turbine slow load reduction unit, the gas turbine slow load reduction unit is connected to the pressure control and low-pressure main steam unit of the steam turbine reducing high and medium pressure, and the pressure control and low-pressure main steam unit of the steam turbine reducing high and medium pressure is connected to the steam turbine shutdown unit.

[0007] A further improvement of the present invention is that the steam turbine shutdown unit is connected to the gas turbine shutdown breakpoint unit.

[0008] A further improvement of the present invention is that the gas turbine shutdown breakpoint unit includes a gas turbine shutdown permission condition unit, a shutdown part auxiliary unit, an intermittent start-stop vacuum pump function group unit and an APS shutdown completion unit; The steam turbine shutdown unit is connected to the gas turbine shutdown permission condition unit, the gas turbine shutdown permission condition unit is connected to the shutdown part auxiliary machine unit, and the shutdown part auxiliary machine unit is respectively connected to the intermittent start and stop vacuum pump function group unit and the APS shutdown completion unit.

[0009] A further improvement of the present invention is that when the turbine shutdown breakpoint unit is "1", the automatic control mode of the shutdown process is selected in the turbine shutdown permission condition.

[0010] A further improvement of the present invention is that when the gas turbine shutdown breakpoint unit is "1", the automatic control mode of the shutdown process is selected in the gas turbine shutdown permission condition.

[0011] A gas-steam combined cycle unit shutdown control method, the method is based on a gas-steam combined cycle unit shutdown control system, a first steam turbine shutdown control mode, including: Complete the exit of the high-pressure feedwater pump variable frequency liquid level adjustment mode in the unit shutdown preparation, and set the preset pressure offset; close the low-pressure feedwater bypass electric valve, exit the condensate pump variable frequency liquid level adjustment mode, and set the preset pressure offset; complete the exit of AGC and CCS modes; complete the reduction of the gas turbine load to 100 MW in the gas turbine load reduction to 100 MW , set the preset value of the medium-pressure drum liquid level; at the same time, set the lower limit preset value of the high-pressure superheater outlet steam and reheater outlet steam temperature, set the desuperheating water regulating valve to switch to manual operation mode and be in the closed state; the steam turbine exits the pressure control of high and medium pressure and the pressure control mode of low-pressure main steam, and the high-pressure main steam pressure and medium-pressure drum liquid level are not greater than the preset value; the high and medium pressure regulating valves are set to the preset values, and the valve position state changes to the preset values; when the steam turbine load is lower than 44MW, the low-pressure main steam and low-pressure main steam regulating valves are in the exit mode, and the high-pressure exhaust ventilation valve and electric regulating valve are in the open mode; the medium-pressure drum liquid level is within the preset value; when the steam turbine load is lower than 21MW, the neutral point grounding knife of the steam turbine main transformer is in the closed state; the steam turbine load is not greater than 10 MW during the steam turbine shutdown, and the steam turbine is directly shut down; the medium-pressure drum liquid level is within the preset value range; the steam turbine main transformer is in the open state, and its speed value is not greater than 2940 r / min and the excitation current is not greater than the preset value range, the generator demagnetization switch is in the closed state; or the steam turbine main transformer is in the open state, its speed value is not greater than 2760 r / min, and the steam turbine main transformer neutral point grounding switch is in the open state.

[0012] A further improvement of the present invention is that the second steam turbine shutdown control mode includes: Complete the exit of the high-pressure feedwater pump variable frequency liquid level adjustment mode in the unit shutdown preparation, and set the preset pressure offset; close the low-pressure feedwater bypass electric valve, exit the condensate pump variable frequency liquid level adjustment mode, and set the preset pressure offset; complete the exit of AGC and CCS modes; complete the reduction of the gas turbine load to 100 MW in the gas turbine load reduction to 100 MW , set the preset value of the medium-pressure drum liquid level; at the same time, set the lower limit preset value of the high-pressure superheater outlet steam and reheater outlet steam temperature, set the desuperheating water regulating valve to switch to manual operation mode and be in the closed state; sliding pressure parameter shutdown, the gas turbine is shut down according to the preset sliding pressure parameter curve of the unit during slow load reduction, and the gas turbine load is simultaneously reduced; sliding pressure parameter shutdown, when the sliding pressure parameter curve shutdown function in manual pressure reduction control is completed, the operator manually exits the pressure control mode; the steam turbine exits the pressure control mode during high and medium pressure pressure reduction and low-pressure main steam, and the high-pressure main steam pressure and medium-pressure drum liquid level are not greater than the preset values; the high and medium pressure regulating valves are set to the preset values, and the valve position status changes to the preset value; when the steam turbine load is lower than 44MW, the low-pressure main steam and the low-pressure main steam regulating valve are in the exit mode, and the high-pressure exhaust ventilation valve and the electric regulating valve are in the open mode; the medium-pressure drum liquid level is within the preset value; when the steam turbine load is lower than 21MW, the neutral point grounding knife of the steam turbine main transformer is in the closed state; the steam turbine load is not greater than 10MW during the steam turbine shutdown, and the steam turbine is directly shut down; the medium-pressure drum liquid level is within the preset value range; the steam turbine main transformer is in the open state, its speed value is not greater than 2940r / min and the excitation current is not greater than the preset value range, and the generator demagnetization switch is in the closed state; or the steam turbine main transformer is in the open state, its speed value is not greater than 2760 r / min, and the neutral point grounding knife of the steam turbine main transformer is in the open state.

[0013] A further improvement of the present invention is that the first gas engine shutdown control mode includes: The gas turbine is turned off, the vacuum pump, EH oil pump, power tower fan, and low-pressure recirculation pump in the stopped auxiliary equipment are in a stopped state, the closed state of the return water electric valve on the AB side of the condenser circulating water is at the preset value, and the high and medium pressure drum liquid level is set to within the preset value range; the gas turbine speed is 600r / min, the high, medium and low pressure bypass valves in the stopped auxiliary equipment are all in a fully closed state, the high, medium and low pressure superheater outlet electric valves on the boiler side are in a fully closed state, and the high and medium pressure drum liquid level is higher than the preset value, and the high and medium pressure feed water pumps are all in a stopped state; when the adjacent machine is in operation, the circulating water system communication valves are all in an open state , the second circulating water pump is in a shutdown state, the circulating water outlet electric valve on the AB side of the condenser is reduced to the preset value range; the engine speed meets the minimum preset value range, and the hydrogen cooler water inlet electric valve is in a closed state; the steam turbine speed is 30r / min to open the vacuum breaking valve, and the vacuum breaking valve in the shutdown shaft seal and auxiliary steam system is in an open state, the vacuum is broken and the steam turbine speed is not greater than the minimum preset value, the shaft seal system automatically stops the control module, and the plant-level auxiliary steam main pipe to the auxiliary steam manifold electric valve, the cold to the auxiliary steam electric valve, the shaft seal electric valve and the air cooler water inlet electric valve are all in a closed state.

[0014] A further improvement of the present invention is that the second gas turbine shutdown control mode includes: The gas turbine is turned off, the vacuum pump, EH oil pump, power tower fan, and low-pressure recirculation pump in the shutdown part of the auxiliary equipment are in a shutdown state, the closed state of the return water electric valve on the AB side of the condenser circulating water is at the preset value, and the high and medium pressure drum liquid level is set to the preset value range; the gas turbine speed is 600r / min, the high, medium and low pressure bypass valves in the shutdown part of the auxiliary equipment are all in a fully closed state, the high, medium and low pressure superheater outlet electric valves on the boiler side are in a fully closed state, and the high and medium pressure drum liquid level is higher than the preset value, and the high and medium pressure feed water pumps are all in a shutdown state; when the adjacent machine is in operation, the circulating water system connecting valves are all in an open state, the second circulating water pump is in a shutdown state, and the circulating water outlet electric valve on the AB side of the condenser is reduced to the preset value range; the gas turbine speed meets the minimum preset value range, and the hydrogen cooler water inlet electric valve is in a closed state; if the unit is shut down without breaking the vacuum state in the intermittent start-stop vacuum pump function group, the intermittent start-stop vacuum pump function module after shutdown is started.

[0015] Compared with the prior art, the present invention has at least the following beneficial technical effects: A gas-steam combined cycle unit shutdown control system provided by the present invention adopts a control logic system to present the technical route of the present invention, and incorporates the shutdown strategies of the auxiliary system parts including high / medium / low pressure water supply system, closed water system, condensate system, auxiliary steam system, shaft sealing system, vacuum system, open water system, and circulating water system into the two control strategy modules of steam turbine shutdown and gas turbine shutdown of the present invention, embeds the operation of each equipment of each auxiliary system into this control system, lightweights the system operation, and meets the goal of customized system control function.

[0016] The present invention provides a shutdown control method for a gas-steam combined cycle unit, which adopts a method combining four control modes, and controls the APS shutdown program built into a conventional DCS system in a way that meets the actual application needs on site, integrates the four breakpoint control breakpoint methods of gas turbine load reduction, gas turbine tripping, waste heat boiler shutdown, and unit shutdown, and changes the shutdown control breakpoints into two breakpoints of steam turbine shutdown and gas turbine shutdown, thereby achieving the goal of full-process automated control.

[0017] In summary, the shutdown control system and method of a gas-steam combined cycle unit described in the present invention, the APS shutdown control strategy is combined with the actual operation on site, to achieve effective control and on-demand shutdown of various systems and equipment of the gas-steam combined cycle unit, to meet the high-pressure and medium-pressure drum water filling during the entire shutdown process, and at the same time save time for the next startup preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a control principle diagram of a shutdown control system for a gas-steam combined cycle unit. DETAILED DESCRIPTION

[0019] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0020] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0021] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0022] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0023] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0024] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0025] The present invention reorganizes and improves the traditional APS shutdown control strategy, and incorporates the shutdown strategies of the auxiliary system parts including high / medium / low pressure water supply system, closed water system, condensate system, auxiliary steam system, shaft seal system, vacuum system, open water system, and circulating water system into the shutdown control system and method of the gas-steam combined cycle unit based on various working conditions, so as to realize the full process control of each subsystem. The shutdown control process is set to be divided into two control strategy modules: steam turbine shutdown and gas turbine shutdown, including 9 control submodules, and the operation of each equipment of each auxiliary system is embedded in the step sequence, and the step sequence design is combined with the specific habits of the operating personnel.

[0026] Example 1 like Figure 1 As shown, the present embodiment provides a gas-steam combined cycle unit shutdown control system, comprising a steam turbine shutdown breakpoint unit 001 and a gas turbine shutdown breakpoint unit 007 which are connected to each other; the steam turbine shutdown breakpoint unit 001 is used to execute the steam turbine shutdown control mode, and when the steam turbine shutdown control is completed, the gas turbine shutdown breakpoint unit 007 is used to execute the gas turbine shutdown control mode.

[0027] Example 2 like Figure 1As shown, the present embodiment provides a gas-steam combined cycle unit shutdown control system, including: a steam turbine shutdown breakpoint unit 001, a steam turbine shutdown permission condition unit 002, a gas turbine load reduction to 100MW unit 003, a steam turbine high and medium pressure pressure control and low pressure main steam unit 004, a gas turbine slow load reduction unit 005, a steam turbine shutdown unit 006, a gas turbine shutdown breakpoint unit 007, a gas turbine shutdown permission condition unit 008, a shutdown part of auxiliary equipment unit 009, an intermittent start and stop vacuum pump function group unit 010 and an APS shutdown completion unit 011.

[0028] Example 3 like Figure 1 As shown, the present embodiment provides a gas-steam combined cycle unit shutdown control method, the first turbine shutdown control mode, including: when the turbine shutdown breakpoint unit 001 is "1". The turbine shutdown permission condition; the unit shutdown preparation 002 control module is sequentially connected to the gas turbine load reduction to 100MW unit 003 control module, the turbine back-off high and medium pressure pressure control and low pressure main steam unit 004 and the turbine shutdown unit 006.

[0029] Control strategy: When the turbine shutdown breakpoint unit 001 is "1", the automatic control mode of the shutdown process selected in the turbine shutdown permission conditions must be met at this time. At the same time, confirm that the operating status of the circulating water pump, vacuum pump and power tower wind is retained, and confirm that the shutdown is not in a broken vacuum state or is in a broken vacuum state. Complete the exit from the high-pressure feedwater pump variable frequency liquid level adjustment mode in the unit shutdown preparation, and set the preset value of the pressure offset; close the low-pressure feedwater bypass electric valve, exit the condensate pump variable frequency liquid level adjustment mode, and set the preset value of the pressure offset. Complete the exit from AGC and CCS modes. Complete the reduction of the turbine load to 100 MW in the turbine load reduction to 100 MW, set the preset value of the medium-pressure drum liquid level; at the same time, set the lower limit preset value of the high-pressure superheater outlet steam and reheater outlet steam temperatures, and set the desuperheating water regulating valve to switch to manual operation mode and be in a closed state. The pressure control mode of the high and medium pressure of the steam turbine is exited, and the high pressure main steam pressure and the medium pressure drum liquid level are not greater than the preset values; the high and medium pressure regulating valves are set to the preset values, and the valve position state changes to the preset values; when the steam turbine load is lower than 44MW, the low pressure main steam and low pressure main steam regulating valves are in the exit mode, and the high exhaust ventilation valve and the electric regulating valve are in the open mode; the medium pressure drum liquid level is within the preset value; when the steam turbine load is lower than 21MW, the neutral point grounding knife of the steam turbine main transformer is in the closed state. During the steam turbine shutdown, the steam turbine load is not greater than 10 MW, and the steam turbine is directly shut down; the medium pressure drum liquid level is within the preset value range; the steam turbine main transformer is in the open state, its speed value is not greater than 2940 r / min and the excitation current is not greater than the preset value range, and the generator demagnetization switch is in the closed state; or the steam turbine main transformer is in the open state, its speed value is not greater than 2760 r / min, and the neutral point grounding knife of the steam turbine main transformer is in the open state. The steam turbine is shut down and the breakpoint is completed 1, indicating that the first steam turbine shutdown control mode has been completed.

[0030] Example 4 like Figure 1 As shown, the present embodiment provides a gas-steam combined cycle unit shutdown control method, the second turbine shutdown control mode, including: when the turbine shutdown breakpoint unit 001 is "1". The turbine shutdown permission condition unit 002 control module is sequentially connected to the gas turbine load reduction to 100MW unit 003 control module; the steam turbine high and medium pressure pressure control and low pressure main steam unit 004; the gas turbine slow load reduction unit 005; the steam turbine shutdown unit 006.

[0031] Control strategy: When the turbine shutdown breakpoint unit 001 is "1", the automatic control mode of the shutdown process in the turbine shutdown permission conditions must be met at this time. At the same time, confirm that the operating status of the circulating water pump, vacuum pump and power tower fan is retained, and confirm that the shutdown is not in a broken vacuum state or in a broken vacuum state. Complete the exit from the high-pressure feedwater pump variable frequency liquid level adjustment mode in the unit shutdown preparation, set the preset value of the pressure offset; close the low-pressure feedwater bypass electric valve, exit the condensate pump variable frequency liquid level adjustment mode, and set the preset value of the pressure offset. Complete the exit from AGC and CCS modes. Complete the reduction of the gas turbine load to 100 MW in the gas turbine load reduction to 100 MW, set the preset value of the medium-pressure drum liquid level; at the same time, set the lower limit preset value of the high-pressure superheater outlet steam and reheater outlet steam temperature, and set the desuperheating water regulating valve to switch to manual operation mode and be in a closed state. Sliding pressure parameter shutdown, the gas turbine is shut down according to the preset sliding pressure parameter curve of the unit during the slow load reduction, and the gas turbine load is synchronously reduced. Sliding pressure parameter shutdown, manual pressure reduction control When the sliding pressure parameter curve shutdown function is completed, the operator manually exits the pressure control mode. The turbine exits the pressure control mode in the high and medium pressure pressure control and low pressure main steam, and the high pressure main steam pressure and medium pressure drum liquid level are not greater than the preset value; the high and medium pressure regulating valves are set to the preset value, and the valve position state changes to the preset value; when the turbine load is lower than 44MW, the low pressure main steam and low pressure main steam regulating valve are in the exit mode, and the high exhaust ventilation valve and electric regulating valve are in the open mode; the medium pressure drum liquid level is within the preset value; when the turbine load is lower than 21MW, the neutral point grounding knife of the turbine main transformer is in the closed state. During the steam turbine shutdown, the steam turbine load is not more than 10MW, and the steam turbine is directly shut down; the medium-pressure drum liquid level is within the preset value range; the steam turbine main transformer is in the open state, its speed value is not more than 2940r / min and the excitation current is not more than the preset value range, and the generator demagnetization switch is in the closed state; or the steam turbine main transformer is in the open state, its speed value is not more than 2760r / min, and the steam turbine main transformer neutral point grounding knife is in the open state. The steam turbine is shut down, and the breakpoint completion is 1, indicating that the first steam turbine shutdown control mode has been completed.

[0032] Example 5 like Figure 1 As shown, this embodiment provides a gas-steam combined cycle unit shutdown control method, the first gas turbine shutdown control mode, including: the gas turbine shutdown permission condition 007 control module is sequentially connected to the gas turbine shutdown permission condition unit 008; the shutdown part of the auxiliary unit 009; the APS shutdown completion unit 011.

[0033] Control strategy: When the gas turbine shutdown breakpoint unit 007 is "1", the automatic control mode of the shutdown process selected in the gas turbine shutdown permission conditions must be met at this time. The gas turbine is decoupled and one circulating pump and the gas turbine generator outlet switches in the three power towers are kept in the open state, ensuring that one circulating water pump is in operation, one circulating water pump is in a stopped state, and three power tower fans are in operation. The gas turbine is turned off, and the vacuum pump, EH oil pump, power tower fan, and low-pressure recirculation pump in the shutdown part of the auxiliary equipment are in a stopped state. The closed state of the return water electric valve on the AB side of the condenser circulating water is at the preset value, and the high and medium pressure drum liquid level is set within the preset value range. The gas turbine speed is 600r / min, the high, medium and low pressure bypass valves in the shutdown auxiliary equipment are all in the fully closed state, the high, medium and low pressure superheater outlet electric valves on the boiler side are in the fully closed state, and the high and medium pressure drum liquid level is higher than the preset value, and the high and medium pressure feed water pumps are all in the shutdown state; when the adjacent machine is in operation, the circulating water system contact valves are all in the open state, the second circulating water pump is in the shutdown state, and the circulating water outlet electric valve on the AB side of the condenser is reduced to the preset value range; the gas turbine speed meets the minimum preset value range, and the hydrogen cooler water inlet electric valve is in the closed state. The steam turbine speed is 30r / min to open the vacuum breaking valve, and the vacuum breaking valve in the shutdown shaft seal and auxiliary steam system is in the open state. The vacuum is broken and the steam turbine speed is not greater than the minimum preset value. The shaft seal system automatically stops the control module, and the plant-level auxiliary steam main pipe to the auxiliary steam header electric valve, the cold to the auxiliary steam electric valve, the shaft seal electric valve and the air cooler water inlet electric valve are all in the closed state. The steam turbine is cranked and the engine speed is less than 5r / min, which means the first engine shutdown control mode has been completed.

[0034] Example 6 like Figure 1 As shown, this embodiment provides a gas-steam combined cycle unit shutdown control method, the second gas turbine shutdown control mode, including: the gas turbine shutdown permission condition 007 control module is connected in sequence to the gas turbine shutdown permission condition unit 008, the shutdown part auxiliary unit 009 and the intermittent start and stop vacuum pump function group unit 010.

[0035] Control strategy: When the gas turbine shutdown breakpoint unit 007 is "1", the automatic control mode of the shutdown process selected in the gas turbine shutdown permission conditions must be met at this time. The gas turbine is decoupled and one circulating pump and the gas turbine generator outlet switches in the three power towers are kept in the open state, ensuring that one circulating water pump is in operation, one circulating water pump is in a stopped state, and three power tower fans are in operation. The gas turbine is turned off, and the vacuum pump, EH oil pump, power tower fan, and low-pressure recirculation pump in the shutdown part of the auxiliary equipment are in a stopped state. The closed state of the return water electric valve on the AB side of the condenser circulating water is at the preset value, and the high and medium pressure drum liquid level is set within the preset value range. The engine speed is 600r / min, the high, medium and low pressure bypass valves in the shutdown auxiliary equipment are all in the fully closed state, the high, medium and low pressure superheater outlet electric valves on the boiler side are in the fully closed state, and the high and medium pressure drum liquid level is higher than the preset value, and the high and medium pressure feed water pumps are in the shutdown state; when the adjacent machine is in operation, the circulating water system contact valves are all in the open state, the second circulating water pump is in the shutdown state, and the circulating water outlet electric valve on the AB side of the condenser is reduced to the preset value range; the engine speed meets the minimum preset value range, and the hydrogen cooler water inlet electric valve is in the closed state. If the unit is shut down without breaking the vacuum state in the intermittent start-stop vacuum pump function group, the intermittent start-stop vacuum pump function module after shutdown is started.

[0036] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0037] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A gas-steam combined cycle unit shutdown control system, characterized in that: It includes a steam turbine shutdown breakpoint unit (001) and a gas turbine shutdown breakpoint unit (007) which are connected to each other; The steam turbine shutdown breakpoint unit (001) is used to execute the steam turbine shutdown control mode. When the steam turbine shutdown control is completed, the gas turbine shutdown breakpoint unit (007) is used to execute the gas turbine shutdown control mode.

2. A gas-steam combined cycle unit shutdown control system according to claim 1, characterized in that: The turbine shutdown breakpoint unit (001) includes the turbine shutdown permission condition unit (002), the gas turbine load reduction to 100MW unit (003), the steam turbine high and medium pressure pressure control and low pressure main steam unit (004), the gas turbine slow load reduction unit (005) and the turbine shutdown unit (006); The steam turbine shutdown permission condition unit (002) is connected to the gas turbine load reduction to 100MW unit (003), and the gas turbine load reduction to 100MW unit (003) is respectively connected to the steam turbine high and medium pressure reduction pressure control and low pressure main steam unit (004) and the gas turbine slow load reduction unit (005), and the gas turbine slow load reduction unit (005) is connected to the steam turbine high and medium pressure reduction pressure control and low pressure main steam unit (004), and the steam turbine high and medium pressure reduction pressure control and low pressure main steam unit (004) is connected to the steam turbine shutdown unit (006).

3. A gas-steam combined cycle unit shutdown control system according to claim 2, characterized in that: The steam turbine shutdown unit (006) is connected to the gas turbine shutdown breakpoint unit (007).

4. A gas-steam combined cycle unit shutdown control system according to claim 3, characterized in that: The gas turbine shutdown breakpoint unit (007) includes a gas turbine shutdown permission condition unit (008), a shutdown part auxiliary unit (009), an intermittent start and stop vacuum pump function group unit (010) and an APS shutdown completion unit (011); The steam turbine shutdown unit (006) is connected to the gas turbine shutdown permission condition unit (008), the gas turbine shutdown permission condition unit (008) is connected to the shutdown part auxiliary machine unit (009), and the shutdown part auxiliary machine unit (009) is respectively connected to the intermittent start and stop vacuum pump function group unit (010) and the APS shutdown completion unit (011).

5. A gas-steam combined cycle unit shutdown control system according to claim 4, characterized in that: When the turbine shutdown breakpoint unit (001) is "1", the automatic control mode of the shutdown process is selected in the turbine shutdown permission conditions.

6. A gas-steam combined cycle unit shutdown control system according to claim 4, characterized in that: When the gas turbine shutdown breakpoint unit (007) is "1", the automatic control mode of the shutdown process is selected in the gas turbine shutdown permission conditions.

7. A gas-steam combined cycle unit shutdown control method, characterized in that: The method is based on a gas-steam combined cycle unit shutdown control system as claimed in claim 4, wherein the first steam turbine shutdown control mode comprises: Complete the exit of the high-pressure feedwater pump variable frequency liquid level adjustment mode in the unit shutdown preparation, and set the preset pressure offset; close the low-pressure feedwater bypass electric valve, exit the condensate pump variable frequency liquid level adjustment mode, and set the preset pressure offset; complete the exit of AGC and CCS modes; complete the reduction of the gas turbine load to 100 MW in the gas turbine load reduction to 100 MW , set the preset value of the medium-pressure drum liquid level; at the same time, set the lower limit preset value of the high-pressure superheater outlet steam and reheater outlet steam temperature, set the desuperheating water regulating valve to switch to manual operation mode and be in the closed state; the steam turbine exits the pressure control of high and medium pressure and the pressure control mode of low-pressure main steam, and the high-pressure main steam pressure and medium-pressure drum liquid level are not greater than the preset value; the high and medium pressure regulating valves are set to the preset values, and the valve position state changes to the preset values; when the steam turbine load is lower than 44MW, the low-pressure main steam and low-pressure main steam regulating valves are in the exit mode, and the high-pressure exhaust ventilation valve and electric regulating valve are in the open mode; the medium-pressure drum liquid level is within the preset value; when the steam turbine load is lower than 21MW, the neutral point grounding knife of the steam turbine main transformer is in the closed state; the steam turbine load is not greater than 10 MW during the steam turbine shutdown, and the steam turbine is directly shut down; the medium-pressure drum liquid level is within the preset value range; the steam turbine main transformer is in the open state, and its speed value is not greater than 2940 r / min and the excitation current is not greater than the preset value range, the generator demagnetization switch is in the closed state; or the steam turbine main transformer is in the open state, its speed value is not greater than 2760 r / min, and the steam turbine main transformer neutral point grounding switch is in the open state.

8. A gas-steam combined cycle unit shutdown control method according to claim 7, characterized in that: The second turbine shutdown control mode includes: Complete the exit of the high-pressure feedwater pump variable frequency liquid level adjustment mode in the unit shutdown preparation, and set the preset pressure offset; close the low-pressure feedwater bypass electric valve, exit the condensate pump variable frequency liquid level adjustment mode, and set the preset pressure offset; complete the exit of AGC and CCS modes; complete the reduction of the gas turbine load to 100 MW in the gas turbine load reduction to 100 MW , set the preset value of the medium-pressure drum liquid level; at the same time, set the lower limit preset value of the high-pressure superheater outlet steam and reheater outlet steam temperature, set the desuperheating water regulating valve to switch to manual operation mode and be in the closed state; sliding pressure parameter shutdown, the gas turbine is shut down according to the preset sliding pressure parameter curve of the unit during slow load reduction, and the gas turbine load is simultaneously reduced; sliding pressure parameter shutdown, when the sliding pressure parameter curve shutdown function in manual pressure reduction control is completed, the operator manually exits the pressure control mode; the steam turbine exits the pressure control mode during high and medium pressure pressure reduction and low-pressure main steam, and the high-pressure main steam pressure and medium-pressure drum liquid level are not greater than the preset values; the high and medium pressure regulating valves are set to the preset values, and the valve position status changes to the preset value; when the steam turbine load is lower than 44MW, the low-pressure main steam and the low-pressure main steam regulating valve are in the exit mode, and the high-pressure exhaust ventilation valve and the electric regulating valve are in the open mode; the medium-pressure drum liquid level is within the preset value; when the steam turbine load is lower than 21MW, the neutral point grounding knife of the steam turbine main transformer is in the closed state; the steam turbine load is not greater than 10MW during the steam turbine shutdown, and the steam turbine is directly shut down; the medium-pressure drum liquid level is within the preset value range; the steam turbine main transformer is in the open state, its speed value is not greater than 2940r / min and the excitation current is not greater than the preset value range, and the generator demagnetization switch is in the closed state; or the steam turbine main transformer is in the open state, its speed value is not greater than 2760 r / min, and the neutral point grounding knife of the steam turbine main transformer is in the open state.

9. A gas-steam combined cycle unit shutdown control method according to claim 8, characterized in that: The first gas turbine shutdown control mode includes: The gas turbine is turned off, the vacuum pump, EH oil pump, power tower fan, and low-pressure recirculation pump in the stopped auxiliary equipment are in a stopped state, the closed state of the return water electric valve on the AB side of the condenser circulating water is at the preset value, and the high and medium pressure drum liquid level is set to within the preset value range; the gas turbine speed is 600r / min, the high, medium and low pressure bypass valves in the stopped auxiliary equipment are all in a fully closed state, the high, medium and low pressure superheater outlet electric valves on the boiler side are in a fully closed state, and the high and medium pressure drum liquid level is higher than the preset value, and the high and medium pressure feed water pumps are all in a stopped state; when the adjacent machine is in operation, the circulating water system communication valves are all in an open state , the second circulating water pump is in a shutdown state, the circulating water outlet electric valve on the AB side of the condenser is reduced to the preset value range; the engine speed meets the minimum preset value range, and the hydrogen cooler water inlet electric valve is in a closed state; the steam turbine speed is 30r / min to open the vacuum breaking valve, and the vacuum breaking valve in the shutdown shaft seal and auxiliary steam system is in an open state, the vacuum is broken and the steam turbine speed is not greater than the minimum preset value, the shaft seal system automatically stops the control module, and the plant-level auxiliary steam main pipe to the auxiliary steam manifold electric valve, the cold to the auxiliary steam electric valve, the shaft seal electric valve and the air cooler water inlet electric valve are all in a closed state.

10. A gas-steam combined cycle unit shutdown control method according to claim 9, characterized in that: The second gas turbine shutdown control mode includes: The gas turbine is turned off, the vacuum pump, EH oil pump, power tower fan, and low-pressure recirculation pump in the shutdown part of the auxiliary equipment are in a shutdown state, the closed state of the return water electric valve on the AB side of the condenser circulating water is at the preset value, and the high and medium pressure drum liquid level is set to the preset value range; the gas turbine speed is 600r / min, the high, medium and low pressure bypass valves in the shutdown part of the auxiliary equipment are all in a fully closed state, the high, medium and low pressure superheater outlet electric valves on the boiler side are in a fully closed state, and the high and medium pressure drum liquid level is higher than the preset value, and the high and medium pressure feed water pumps are all in a shutdown state; when the adjacent machine is in operation, the circulating water system connecting valves are all in an open state, the second circulating water pump is in a shutdown state, and the circulating water outlet electric valve on the AB side of the condenser is reduced to the preset value range; the gas turbine speed meets the minimum preset value range, and the hydrogen cooler water inlet electric valve is in a closed state; if the unit is shut down without breaking the vacuum state in the intermittent start-stop vacuum pump function group, the intermittent start-stop vacuum pump function module after shutdown is started.

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