Bypass system control system for steam turbine units

Abstract

The application provides a bypass system control system of a steam turbine unit, comprising a high-pressure cylinder (1), a medium-pressure cylinder (2), a boiler (3), a high-bypass desuperheating water regulating valve (6) and a high-bypass desuperheater (7) arranged on a high-bypass desuperheating water pipeline (19), a first low-bypass desuperheating water regulating valve (11) and a first low-bypass desuperheater (12) arranged on a first low-bypass desuperheating water pipeline (21), a second low-bypass desuperheating water regulating valve (14) and a second low-bypass desuperheater (13) arranged on a second low-bypass desuperheating water pipeline (23), a high-bypass pressure reducing valve (4) arranged on a high-bypass pipeline (20), a first low-bypass pressure reducing valve (8) arranged on a first low-bypass pipeline (22), and a second low-bypass pressure reducing valve (9) arranged on a second low-bypass pipeline (24). The application has a high automation level, avoids the problem of over-temperature of the high-bypass and low-bypass pipelines, and makes the unit have high reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of steam turbine units, in particular to a bypass system control system of a steam turbine unit. BACKGROUND

[0002] The thermal power generating unit converts water into high-pressure steam through a boiler, and then sends the high-pressure steam to the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder of the steam turbine to drive the steam turbine to rotate and generate electricity. The bypass system can make the steam turbine inlet steam parameter steadily increase until meeting the requirements of the steam turbine during the cold state, warm state, hot state and extremely hot state startup process of the unit, thereby shortening the startup time of the unit.

[0003] The existing steam turbine bypass control system has low automation level, cannot control the water temperature of the high and low bypass desuperheating water, and has the problem of high and low bypass pipeline over-temperature. Moreover, manual operation of each control valve is required, which is inconvenient to use and prone to errors, affecting the safe operation of the unit. SUMMARY

[0004] The purpose of the present application is to provide a bypass system control system of a steam turbine unit, so that the unit has a high automation level. At the same time, the method includes the corresponding control of the high and low bypass desuperheating water, avoids the problem of high and low bypass pipeline over-temperature, and makes the unit have high reliability.

[0005] In order to achieve the above purpose, the present application discloses a bypass system control system of a steam turbine unit, comprising:

[0006] A bypass system control system of a steam turbine unit, comprising: a high-pressure cylinder 1, a medium-pressure cylinder 2, a boiler 3, a high bypass desuperheating water regulating valve 6 and a high bypass desuperheater 7 arranged on a high bypass desuperheating water pipeline 19, a first low bypass desuperheating water regulating valve 11 and a first low bypass desuperheater 12 arranged on a first low bypass desuperheating water pipeline 21, a second low bypass desuperheating water regulating valve 14 and a second low bypass desuperheater 13 arranged on a second low bypass desuperheating water pipeline 23, a high bypass pressure reducing valve 4 arranged on a high bypass pipeline 20, a first low bypass pressure reducing valve 8 arranged on a first low bypass pipeline 22, and a second low bypass pressure reducing valve 9 arranged on a second low bypass pipeline 24.

[0007] The main steam generated in the boiler 3 enters the high-pressure cylinder 1 through a main steam pipeline 16; the steam generated by the work of the high-pressure cylinder 1 enters the boiler 3 through a reheating cold end pipeline 17, is heated to generate reheated steam, and enters the medium-pressure cylinder 2 through a reheated steam pipeline 18.

[0008] The high bypass pipe 20 is connected with the main steam pipe 16 and the reheated cold end pipe 17 at two ends respectively; the two ends of the high bypass desuperheating water pipe 19 are connected with a water supply pump and the high bypass pipe 20 respectively; the two ends of the first low bypass pipe 22 are connected with a reheated steam pipe 18 and a condenser 25 respectively, and the two ends of the first low bypass desuperheating water pipe 21 are connected with a condensate pump and the first low bypass pipe 22 respectively; the two ends of the second low bypass pipe 24 are connected with the reheated steam pipe 18 and the condenser 25 respectively, and the two ends of the second low bypass desuperheating water pipe 23 are connected with the condensate pump and the second low bypass pipe 24 respectively.

[0009] Further, the first pressure sensor 26 is arranged on the main steam pipe 16 and located between the boiler 3 and the high bypass pipe 20.

[0010] Further, the second pressure sensor 27 is arranged on the high bypass pipe 20 and located between the high bypass desuperheating water pipe 19 and the reheated cold end pipe 17.

[0011] Further, the third pressure sensor 28 is arranged on the reheated steam pipe 18 and located between the boiler 3 and the first low bypass pipe 22.

[0012] Further, the first temperature sensor 29 is arranged on the high bypass pipe 20 and located between the second pressure sensor 27 and the reheated cold end pipe 17.

[0013] Further, the second temperature sensor 30 is arranged on the first low bypass pipe 22 and located between the first low bypass desuperheating water pipe 21 and the condenser 25.

[0014] Further, the third temperature sensor 31 is arranged on the second low bypass pipe 24 and located between the second low bypass desuperheating water pipe 23 and the condenser 25.

[0015] Further, the high bypass isolation valve 5 is arranged on the high bypass desuperheating water pipe 19.

[0016] Further, the first low bypass isolation valve 10 is arranged on the first low bypass desuperheating water pipe 21.

[0017] Further, the second low bypass isolation valve 15 is arranged on the second low bypass desuperheating water pipe 23.

[0018] The bypass system control system of the steam turbine unit provided by the embodiment of the application realizes automatic control of bypass pressure building, bypass pressure stabilization, bypass grid connection and the like, the method is flexible and simple to operate and easy to implement, so that the unit has a high automation level; meanwhile, the method includes corresponding control of high bypass and low bypass desuperheating water, avoids high and low bypass pipeline over-temperature problems, so that the unit has high reliability; and the method is suitable for high and intermediate pressure combined starting units and intermediate pressure cylinder starting units, and has a wide application range. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort based on these drawings. In the drawings:

[0020] Figure 1 is a structural diagram of the bypass system control system of the steam turbine unit of the present application;

[0021] Figure 2 is a function curve diagram of the mapping relationship between the main steam pressure and the high bypass pressure reducing valve 4 of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort fall within the scope of protection of the present application.

[0023] It should be noted that the bypass system control system of the steam turbine unit disclosed by the present application can be used in the field of steam turbines, and can also be used in any field other than the field of steam turbines, and the application field of the bypass system control system of the steam turbine unit disclosed by the present application is not limited.

[0024] The bypass system control system of the steam turbine unit disclosed by the present application, like Figure 1As shown, the bypass system control system of the steam turbine unit includes: a high-pressure cylinder 1, an intermediate-pressure cylinder 2, a boiler 3, a high-pressure bypass desuperheating water regulating valve 6 and a high-pressure bypass desuperheater 7 installed on the high-pressure bypass desuperheating water pipeline 19, a first low-pressure bypass desuperheating water regulating valve 11 and a first low-pressure bypass desuperheater 12 installed on the first low-pressure bypass desuperheating water pipeline 21, a second low-pressure bypass desuperheating water regulating valve 14 and a second low-pressure bypass desuperheater 13 installed on the second low-pressure bypass desuperheating water pipeline 23, a high-pressure bypass pressure reducing valve 4 installed on the high-pressure bypass pipeline 20, a first low-pressure bypass pressure reducing valve 8 installed on the first low-pressure bypass pipeline 22, and a second low-pressure bypass pressure reducing valve 9 installed on the second low-pressure bypass pipeline 24.

[0025] The main steam generated in boiler 3 enters high-pressure cylinder 1 through main steam pipe 16; the steam generated by high-pressure cylinder 1 during operation enters boiler 3 through reheat cold end pipe 17, is heated to generate reheat steam, and enters the intermediate-pressure cylinder 2 through reheat steam pipe 18.

[0026] The high-pressure bypass pipe 20 is connected at both ends to the main steam pipe 16 and the reheat cold end pipe 17, respectively; the high-pressure bypass desuperheating water pipe 19 is connected at both ends to the feed water pump (located in...). Figure 1 The left end of the high-pressure bypass desuperheating water pipe 19 (not shown in the figure) and the high-pressure bypass pipe 20; the two ends of the first low-pressure bypass pipe 22 are respectively connected to the reheat steam pipe 18 and the condenser 25, and the two ends of the first low-pressure bypass desuperheating water pipe 21 are respectively connected to the condensate pump (located in...). Figure 1 The left end of the first low-temperature bypass desuperheating water pipe 21 (not shown in the figure) and the first low-temperature bypass pipe 22; the two ends of the second low-temperature bypass pipe 24 are respectively connected to the reheat steam pipe 18 and the condenser 25, and the two ends of the second low-temperature bypass desuperheating water pipe 23 are respectively connected to the condensate pump (located in...). Figure 1 The left end of the second low-temperature bypass cooling water pipe 23 (not shown in the figure) and the second low-temperature bypass pipe 24.

[0027] from Figure 1 As shown in the diagram, the main steam generated by boiler 3 enters high-pressure cylinder 1 through main steam pipe 16 to perform work. The steam after performing work in high-pressure cylinder 1 enters boiler 3 again through reheat cold end pipe 17 for heating. The steam after being heated by boiler 3 enters intermediate-pressure cylinder 2 through reheat steam pipe 18 to continue performing work. Part of the main steam flows into the reheat cold end pipe through high-pressure bypass pipe 20, and part of the reheat steam enters condenser 25 through first low-pressure bypass pipe 22 and second low-pressure bypass pipe 24.

[0028] Each component is explained in detail below:

[0029] In an embodiment, the bypass system control system of the steam turbine unit further comprises a high bypass isolation valve 5, a high bypass desuperheating water regulating valve 6 and a high bypass desuperheater 7. The high bypass isolation valve 5, the high bypass desuperheating water regulating valve 6 and the high bypass desuperheater 7 are arranged on the high bypass desuperheating water pipeline 19, and the high bypass desuperheating water regulating valve 6 is arranged between the high bypass isolation valve 5 and the high bypass desuperheater 7. The high bypass isolation valve 5 is arranged on the high bypass desuperheating water pipeline 19 close to one end of the feed water pump, and the high bypass desuperheater 7 is arranged on the high bypass desuperheating water pipeline 19 close to one end of the high bypass pipeline 20. The high bypass isolation valve 5 is used to control the isolation and passage of the high bypass desuperheating water pipeline 19. The high bypass desuperheating water regulating valve 6 is used to regulate the flow of desuperheating water in the high bypass desuperheating water pipeline 19. The high bypass desuperheater 7 is used to atomize the desuperheating water in the high bypass desuperheating water pipeline 19, which can effectively reduce the steam temperature of the high bypass desuperheating water pipeline 19.

[0030] In an embodiment, the bypass system control system of the steam turbine unit further comprises a first low bypass isolation valve 10. The first low bypass isolation valve 10, a first low bypass desuperheating water regulating valve 11 and a first low bypass desuperheater 12 are arranged on the first low bypass desuperheating water pipeline 21, and the first low bypass desuperheating water regulating valve 11 is arranged between the first low bypass isolation valve 10 and the first low bypass desuperheater 12. The first low bypass isolation valve 10 is arranged on the first low bypass desuperheating water pipeline 21 close to one end of the condensate pump, and the first low bypass desuperheater 12 is arranged on the first low bypass desuperheating water pipeline 21 close to one end of the first low bypass pipeline 22. The first low bypass isolation valve 10 is used to control the isolation and passage of the first low bypass desuperheating water pipeline 21. The first low bypass desuperheating water regulating valve 11 is used to regulate the flow of desuperheating water in the first low bypass desuperheating water pipeline 21. The first low bypass desuperheater 12 is used to atomize the desuperheating water in the first low bypass desuperheating water pipeline 21, which can effectively reduce the steam temperature of the first low bypass desuperheating water pipeline 21.

[0031] In an embodiment, the bypass system control system of the steam turbine unit further comprises a second low bypass isolation valve 15. The second low bypass isolation valve 15, a second low bypass desuperheating water regulating valve 14 and a second low bypass desuperheater 13 are arranged on the second low bypass desuperheating water pipeline 23, and the second low bypass desuperheating water regulating valve 14 is arranged between the second low bypass isolation valve 15 and the second low bypass desuperheater 13. The second low bypass isolation valve 15 is arranged on the second low bypass desuperheating water pipeline 23 close to one end of the condensate pump, and the second low bypass desuperheater 13 is arranged on the second low bypass desuperheating water pipeline 23 close to one end of the second low bypass pipeline 24. The second low bypass isolation valve 15 is used to control the isolation and passage of the second low bypass desuperheating water pipeline 23. The second low bypass desuperheating water regulating valve 14 is used to regulate the flow of desuperheating water in the second low bypass desuperheating water pipeline 23. The second low bypass desuperheater 13 is used to atomize the desuperheating water in the second low bypass desuperheating water pipeline 23, which can effectively reduce the steam temperature of the second low bypass desuperheating water pipeline 23.

[0032] A high bypass pressure reducing valve 4 is arranged on the high bypass pipe 20, and is arranged between the high bypass desuperheating water pipe 19 and the main steam pipe 16, and is used to adjust the steam pressure on the high bypass pipe 20.

[0033] A first low bypass pressure reducing valve 8 is arranged on the first low bypass pipe 22, and is arranged between the first low bypass desuperheating water pipe 21 and the reheated cold end pipe 17, and is used to adjust the steam pressure on the first low bypass pipe 22.

[0034] A second low bypass pressure reducing valve 9 is arranged on the second low bypass pipe 24, and is arranged between the second low bypass desuperheating water pipe 23 and the reheated cold end pipe 17, and is used to adjust the steam pressure on the second low bypass pipe 24.

[0035] In an embodiment, a condenser 25 is arranged at one end of the first low bypass pipe 22 and the second low bypass pipe 24, and is used to condense the steam in the first low bypass pipe 22 and the second low bypass pipe 24 into water.

[0036] In an embodiment, a first pressure sensor 26 is arranged on the main steam pipe 16, and is located between the boiler 3 and the high bypass pipe 20, and is used to detect the steam pressure on the main steam pipe 16.

[0037] In an embodiment, a second pressure sensor 27 is arranged on the high bypass pipe 20, and is located between the high bypass desuperheating water pipe 19 and the reheated cold end pipe 17, and is used to detect the steam pressure on the high bypass pipe 20.

[0038] In an embodiment, a third pressure sensor 28 is arranged on the reheated steam pipe 18, and is located between the boiler 3 and the first low bypass pipe 22, and is used to detect the steam pressure on the reheated steam pipe 18.

[0039] In an embodiment, a first temperature sensor 29 is arranged on the high bypass pipe 20, and is located between the second pressure sensor 28 and the reheated cold end pipe 17, and is used to detect the steam temperature on the high bypass pipe 20.

[0040] In an embodiment, a second temperature sensor 30 is arranged on the first low bypass pipe 22, and is located between the first low bypass desuperheating water pipe 21 and the condenser 25, and is used to detect the steam temperature on the first low bypass pipe 22.

[0041] In an embodiment, a third temperature sensor 31 is arranged on the second low bypass pipe 24, and is located between the second low bypass desuperheating water pipe 23 and the condenser 25, and is used to detect the steam temperature on the second low bypass pipe 24.

[0042] In one embodiment, the conditions for activating the bypass system control system of the steam turbine unit are: the boiler has a combustion memory delay of 600s and the unit is not connected to the grid. Combustion memory refers to the operation of any coal feeder and the corresponding coal mill, with a delay of 180s.

[0043] The automatic bypass control process for the combined high-pressure and medium-pressure start-up unit is as follows: Boiler 3 generates main steam, which is transmitted to the high-pressure cylinder 1 via main steam pipeline 16. When the main steam pressure detected by the first pressure sensor 26 on the main steam pipeline 16 is greater than 0.5 MPa, based on the preset opening curve of the high-pressure bypass pressure reducing valve 4 and the target main steam pressure value, the valve opening of the high-pressure bypass pressure reducing valve 4 is adjusted to the target valve position. The valve openings of the first low-pressure bypass pressure reducing valve 8 and the second low-pressure bypass pressure reducing valve 9 are adjusted to 20% at a rate of 2.5% / s. Figure 2 As shown, the preset opening curve of the high-pressure bypass pressure reducing valve 4 is a function curve about the mapping relationship between the main steam pressure and the high-pressure bypass pressure reducing valve 4. The relationship curves are X: (0.5, 1, 2, 3, 4, 5, 6, 7, 8), Y: (5, 15, 25, 35, 45, 55, 65, 65, 65, 65).

[0044] When the opening degree of the high-pressure bypass pressure reducing valve 4 is greater than 3%, the high-pressure bypass isolation valve 5 is interlocked open; when the opening degree of the first low-pressure bypass pressure reducing valve 8 is greater than 3%, the first low-pressure bypass isolation valve 10 is interlocked open; when the opening degree of the second low-pressure bypass pressure reducing valve 9 is greater than 3%, the second low-pressure bypass isolation valve 15 is interlocked open.

[0045] When the steam temperature detected by the first temperature sensor 29 on the high-pressure bypass pipeline 20 exceeds 280℃, the high-pressure bypass desuperheating water regulating valve 6 automatically engages in automatic temperature control, setting its setpoint to 295℃. After engaging automatic temperature control, the valve opening of the high-pressure bypass desuperheating water regulating valve 6 is adjusted according to the steam temperature detected by the first temperature sensor 29.

[0046] When the steam temperature detected by the second temperature sensor 30 on the first low-temperature bypass pipe 22 is greater than 60°C, the first low-temperature bypass desuperheating water regulating valve 11 automatically engages in automatic temperature control, setting its temperature control setpoint to 70°C. After the first low-temperature bypass desuperheating water regulating valve 11 engages in automatic temperature control, the valve opening is adjusted according to the steam temperature detected by the second temperature sensor 30.

[0047] When the steam temperature detected by the third temperature sensor 31 on the second low-temperature bypass pipe 24 is greater than 60°C, the second low-temperature bypass desuperheating water regulating valve 14 automatically engages in automatic temperature control, setting its temperature control setpoint to 70°C. After the second low-temperature bypass desuperheating water regulating valve 14 engages in automatic temperature control, the valve opening is adjusted according to the steam temperature detected by the third temperature sensor 31.

[0048] When the valve opening degree of the high bypass pressure reducing valve 4 is greater than 30% and the main steam pressure detected by the first pressure sensor 26 is greater than the preset first pressure value, the high bypass pressure reducing valve 4 is put into pressure automatic control, and the pressure control set value of the main steam is set as the current main steam pressure value.

[0049] Wherein, after the high bypass pressure reducing valve 4 is put into pressure automatic control, the opening degree of the high bypass pressure reducing valve 4 is adjusted according to the main steam pressure detected by the first pressure sensor 26.

[0050] Wherein, the preset first pressure value refers to the car running main steam pressure value set according to the starting state of the steam turbine. When the unit is cold started, the preset first pressure value is 5 MPa; when the unit is warm started, the preset first pressure value is 6 MPa; when the unit is hot started, the preset first pressure value is 7 MPa; and when the unit is extremely hot started, the preset first pressure value is 8 MPa.

[0051] When the reheated steam pressure detected by the third pressure sensor 28 on the reheated steam pipeline 18 is greater than the preset second pressure value, the first low bypass pressure reducing valve 8 is put into pressure automatic control, and the second low bypass pressure reducing valve 9 is put into pressure automatic control, and the pressure control set value of the reheated steam is set as the current reheated steam pressure value.

[0052] In an embodiment, the preset second pressure value is 0.8 MPa.

[0053] In an embodiment, the pressure automatic control of the high bypass pressure reducing valve 4 has a valve position biasing function. When the valve opening degree of the high bypass pressure reducing valve 4 is greater than 80%, the valve position of the high bypass pressure reducing valve 4 is appropriately reduced by artificially outputting pressure biasing, so that the valve opening degree of the high bypass pressure reducing valve 4 does not exceed 80%, thereby avoiding excessive valve opening degree of the high bypass pressure reducing valve 4 causing vibration of the high bypass pipeline 20.

[0054] In an embodiment, the pressure automatic control of the first low bypass pressure reducing valve 8 has a valve position biasing function. When the valve opening degree of the first low bypass pressure reducing valve 8 is greater than 80%, the valve position of the first low bypass pressure reducing valve 8 is appropriately reduced by artificially outputting pressure biasing, so that the first low bypass pressure reducing valve 8 does not exceed 80%, thereby avoiding excessive valve opening degree of the first low bypass pressure reducing valve 8 causing vibration of the first low bypass pipeline 22.

[0055] In an embodiment, the pressure automatic control of the second low bypass pressure reducing valve 9 has a valve position biasing function. When the valve opening degree of the second low bypass pressure reducing valve 9 is greater than 80%, the valve position of the second low bypass pressure reducing valve 9 is appropriately reduced by artificially outputting pressure biasing, so that the second low bypass pressure reducing valve 9 does not exceed 80%, thereby avoiding excessive valve opening degree of the second low bypass pressure reducing valve 9 causing vibration of the second low bypass pipeline 24.

[0056] When the load of the high and medium pressure combined starting unit is greater than the preset first power, the valve position of the high bypass pressure reducing valve is switched from automatic control to manual control, the valve position opening of the high bypass pressure reducing valve 4 is closed to 0 at a preset first closing rate, the valve positions of the first and second low bypass pressure reducing valves 8 and 9 are switched from automatic control to manual control, and the first and second low bypass pressure reducing valves 8 and 9 are closed to 0 at a preset second closing rate, and the automatic control of the full bypass is removed.

[0057] In an embodiment, the preset first power is 20 MW, the preset first closing rate is 1.5% / s, and the preset second closing rate is 5% / s.

[0058] The automatic control process of the full bypass of the medium pressure cylinder starting unit is as follows: the boiler 3 generates main steam through heating, which is transmitted to the high pressure cylinder 1 through the main steam pipeline 16. When the main steam pressure detected by the first pressure sensor 26 on the main steam pipeline 16 is greater than 0.5 MPa, the valve position opening of the high bypass pressure reducing valve 4 is adjusted to the target valve position according to the preset opening curve of the high bypass pressure reducing valve 4 and the target main steam pressure value, and the valve position openings of the first and second low bypass pressure reducing valves 8 and 9 are adjusted to 20% at a rate of 2.5% / s. As shown in the figure, the preset opening curve of the high bypass pressure reducing valve 4 is a function curve of the mapping relationship between the main steam pressure and the high bypass pressure reducing valve 4, and the relationship curve is X: (0.5, 1, 2, 3, 4, 5, 6, 7, 8), Y: (5, 15, 25, 35, 45, 55, 65, 65, 65, 65). Figure 2

[0059] When the valve position opening of the high bypass pressure reducing valve 4 is greater than 3%, the high bypass isolation valve 5 is opened by interlocking; when the valve position opening of the first low bypass pressure reducing valve 8 is greater than 3%, the first low bypass isolation valve 10 is opened by interlocking; and when the valve position opening of the second low bypass pressure reducing valve 9 is greater than 3%, the second low bypass isolation valve 15 is opened by interlocking.

[0060] When the steam temperature detected by the first temperature sensor 29 on the high bypass pipeline 20 is greater than 280℃, the high bypass desuperheating water regulating valve 6 is automatically put into temperature automatic control, and the temperature setting value of the high bypass desuperheating water regulating valve 6 is set to 295℃. After the high bypass desuperheating water regulating valve 6 is put into temperature automatic control, the valve position opening is adjusted according to the steam temperature detected by the first temperature sensor 29.

[0061] When the steam temperature detected by the second temperature sensor 30 on the first low bypass pipeline 22 is greater than 60℃, the first low bypass desuperheating water regulating valve 11 is automatically put into temperature automatic control, and the temperature control setting value of the first low bypass desuperheating water regulating valve 11 is set to 70℃. After the first low bypass desuperheating water regulating valve 11 is put into temperature automatic control, the valve position opening is adjusted according to the steam temperature detected by the second temperature sensor 30. ​

[0062] When the steam temperature detected by the third temperature sensor 31 on the second low bypass pipe 24 is greater than 60℃, the second low bypass desuperheating valve 14 automatically enters temperature automatic control, and the temperature control set value of the second low bypass desuperheating valve 14 is set to 70℃. After the second low bypass desuperheating valve 14 enters temperature automatic control, the valve opening degree is adjusted according to the steam temperature detected by the third temperature sensor 31.

[0063] When the valve opening degree of the high bypass pressure reducing valve 4 is greater than 30% and the main steam pressure detected by the first pressure sensor 26 is greater than a preset first pressure value, the high bypass pressure reducing valve 4 enters pressure automatic control, and the pressure control set value of the main steam is set to the current main steam pressure value.

[0064] After the high bypass pressure reducing valve 4 enters pressure automatic control, the opening degree of the high bypass pressure reducing valve 4 is adjusted according to the main steam pressure detected by the first pressure sensor 26.

[0065] The preset first pressure value refers to the car-starting main steam pressure value set according to the starting state of the steam turbine. When the unit is cold-started, the preset first pressure value is 5 MPa; when the unit is warm-started, the preset first pressure value is 6 MPa; when the unit is hot-started, the preset first pressure value is 7 MPa; and when the unit is extremely hot-started, the preset first pressure value is 8 MPa.

[0066] When the reheat steam pressure detected by the third pressure sensor 28 on the reheat steam pipe 18 is greater than a preset second pressure value, the first low bypass pressure reducing valve 8 enters pressure automatic control, and the second low bypass pressure reducing valve 9 enters pressure automatic control, and the pressure control set value of the reheat steam is set to the current reheat steam pressure value.

[0067] In an embodiment, the preset second pressure value is 0.8 MPa.

[0068] In an embodiment, the pressure automatic control of the high bypass pressure reducing valve 4 has a valve position biasing function. When the valve opening degree of the high bypass pressure reducing valve 4 is greater than 80%, the valve opening degree of the high bypass pressure reducing valve 4 is appropriately reduced by artificially outputting pressure biasing so that the valve opening degree of the high bypass pressure reducing valve 4 does not exceed 80%, thereby avoiding excessive valve opening degree of the high bypass pressure reducing valve 4 causing vibration of the high bypass pipe 20.

[0069] In an embodiment, the pressure automatic control of the first low bypass pressure reducing valve 8 has a valve position biasing function. When the valve opening degree of the first low bypass pressure reducing valve 8 is greater than 80%, the valve opening degree of the first low bypass pressure reducing valve 8 is appropriately reduced by artificially outputting pressure biasing so that the valve opening degree of the first low bypass pressure reducing valve 8 does not exceed 80%, thereby avoiding excessive valve opening degree of the first low bypass pressure reducing valve 8 causing vibration of the first low bypass pipe 22.

[0070] In an embodiment, the pressure automatic control of the second low bypass pressure reducing valve 9 has a valve position biasing function. When the valve position opening of the second low bypass pressure reducing valve 9 is greater than 80%, the valve position of the second low bypass pressure reducing valve 9 is appropriately reduced by artificially outputting pressure biasing, so that the second low bypass pressure reducing valve 9 does not exceed 80%, thereby avoiding excessive valve position opening of the second low bypass pressure reducing valve 9 causing vibration of the second low bypass pipeline 24.

[0071] When the cylinder switching instruction comes when the medium-pressure cylinder starting unit is connected to the grid, the valve position of the high bypass pressure reducing valve 4 is switched from automatic control to manual control, the high bypass pressure reducing valve 4 is closed to 0 at a preset first closing rate, the valve position of the first low bypass pressure reducing valve 8 and the valve position of the second low bypass pressure reducing valve 9 are switched from automatic control to manual control, and the valve position of the first low bypass pressure reducing valve and the valve position of the second low bypass pressure reducing valve are closed to 0 at a preset second closing rate, and the full-range bypass automatic control is removed.

[0072] The preset first closing rate is 1.5% / s, and the preset second closing rate is 5% / s. The cylinder switching instruction refers to switching the unit from medium-pressure cylinder admission to high-medium-pressure cylinder combined admission after the medium-pressure cylinder starting unit is connected to the grid.

[0073] By using the present application, automatic control of bypass pressure building, bypass pressure stabilization, bypass grid connection and the like is realized. The method is flexible and simple to operate, easy to implement, and makes the unit have a high level of automation. At the same time, the method includes corresponding control of high and low bypass desuperheating water, avoids high and low bypass pipeline over-temperature problems, and makes the unit have high reliability. The method is suitable for high-medium-pressure combined starting units and medium-pressure cylinder starting units, and has a wide range of applications.

[0074] The above-described specific embodiments further illustrate the purpose, technical solutions and advantages of the present application. It should be understood that the above-described embodiments are only specific embodiments of the present application and are not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A bypass system control system for a steam turbine unit, characterized in that, include: High-pressure cylinder (1), medium-pressure cylinder (2), boiler (3), first pressure sensor (26), second pressure sensor (27), first temperature sensor (29), second temperature sensor (30), third temperature sensor (31), high-pressure bypass desuperheating water regulating valve (6) and high-pressure bypass desuperheater (7) installed on the high-pressure bypass desuperheating water pipeline (19), first low-pressure bypass desuperheating water regulating valve (11) and first low-pressure bypass desuperheater (12) installed on the first low-pressure bypass desuperheating water pipeline (21), and second low-pressure bypass desuperheater installed on the second low-pressure bypass desuperheating water pipeline (23). Water regulating valve (14) and second low-side desuperheater (13), high-side pressure reducing valve (4) installed on high-side pipeline (20), first low-side pressure reducing valve (8) installed on first low-side pipeline (22), second low-side pressure reducing valve (9) installed on second low-side pipeline (24), high-side isolation valve (5) installed on the high-side desuperheating water pipeline (19), first low-side isolation valve (10) installed on the first low-side desuperheating water pipeline (21), and second low-side isolation valve (15) installed on the second low-side desuperheating water pipeline (23); The main steam generated in the boiler (3) enters the high-pressure cylinder (1) through the main steam pipe (16); the steam generated by the high-pressure cylinder (1) during operation enters the boiler (3) through the reheat cold end pipe (17), and after being heated, it generates reheat steam and enters the medium-pressure cylinder (2) through the reheat steam pipe (18); The high-speed bypass pipe (20) is connected to the main steam pipe (16) and the reheat cold end pipe (17) at both ends respectively; the high-speed bypass desuperheating water pipe (19) is connected to the feed water pump and the high-speed bypass pipe (20) at both ends respectively; the first low-speed bypass pipe (22) is connected to the reheat steam pipe (18) and the condenser (25) at both ends respectively; the first low-speed bypass desuperheating water pipe (21) is connected to the condensate pump and the first low-speed bypass pipe (22) at both ends respectively; the second low-speed bypass pipe (24) is connected to the reheat steam pipe (18) and the condenser (25) at both ends respectively; the second low-speed bypass desuperheating water pipe (23) is connected to the condensate pump and the second low-speed bypass pipe (24) at both ends respectively. The second pressure sensor (27) is installed on the high bypass pipe (20) and located between the high bypass desuperheating water pipe (19) and the reheat cold end pipe (17); The first temperature sensor (29) is disposed on the high bypass pipe (20) and located between the second pressure sensor (27) and the reheat cold end pipe (17); The first pressure sensor (26) is installed on the main steam pipe (16) and located between the boiler (3) and the high-pressure bypass pipe (20); The second temperature sensor (30) is installed on the first low-temperature bypass pipe (22) and is located between the first low-temperature bypass desuperheating water pipe (21) and the condenser (25); The third temperature sensor (31) is installed on the second low-temperature bypass pipe (24) and is located between the second low-temperature bypass desuperheating water pipe (23) and the condenser (25); The full bypass automatic control process of the high-pressure combined start-up unit or the medium-pressure cylinder start-up unit includes: the boiler (3) generates main steam through heating and transmits it to the high-pressure cylinder (1) via the main steam pipeline (16). When the main steam pressure detected by the first pressure sensor (26) on the main steam pipeline (16) is greater than 0.5 MPa, the valve position opening of the high-pressure bypass pressure reducing valve (4) is adjusted to the target valve position according to the preset opening curve of the high-pressure bypass pressure reducing valve (4) and the target main steam pressure value. The valve position opening of the first low-pressure bypass pressure reducing valve (8) and the second low-pressure bypass pressure reducing valve (9) is adjusted to 20% at a rate of 2.5% / s. When the valve position opening of the high bypass pressure reducing valve (4) is greater than 3%, the high bypass isolation valve (5) is interlocked open; when the valve position opening of the first low bypass pressure reducing valve (8) is greater than 3%, the first low bypass isolation valve (10) is interlocked open; when the valve position opening of the second low bypass pressure reducing valve (9) is greater than 3%, the second low bypass isolation valve (15) is interlocked open. When the steam temperature detected by the first temperature sensor (29) on the high-pressure bypass pipe (20) is greater than 280°C, the high-pressure bypass desuperheating water regulating valve (6) automatically engages in automatic temperature control and sets the temperature setpoint of the high-pressure bypass desuperheating water regulating valve (6) to 295°C; wherein, after the high-pressure bypass desuperheating water regulating valve (6) engages in automatic temperature control, the valve opening is adjusted according to the steam temperature detected by the first temperature sensor (29); When the steam temperature detected by the second temperature sensor (30) on the first low-temperature bypass pipe (22) is greater than 60°C, the first low-temperature bypass desuperheating water regulating valve (11) automatically engages in automatic temperature control and sets the temperature control setpoint of the first low-temperature bypass desuperheating water regulating valve (11) to 70°C; wherein, after the first low-temperature bypass desuperheating water regulating valve (11) engages in automatic temperature control, the valve opening is adjusted according to the steam temperature detected by the second temperature sensor (30); When the steam temperature detected by the third temperature sensor (31) on the second low-temperature bypass pipe (24) is greater than 60°C, the second low-temperature bypass desuperheating water regulating valve (14) automatically engages in automatic temperature control and sets the temperature control setpoint of the second low-temperature bypass desuperheating water regulating valve (14) to 70°C; wherein, after the second low-temperature bypass desuperheating water regulating valve (14) engages in automatic temperature control, the valve opening is adjusted according to the steam temperature detected by the third temperature sensor (31); When the valve position opening of the high pressure bypass pressure reducing valve (4) is greater than 30%, and the main steam pressure detected by the first pressure sensor (26) is greater than the preset first pressure value, the high pressure bypass pressure reducing valve (4) puts into automatic pressure control and sets the pressure control setpoint of the main steam to the current main steam pressure value. After the high pressure bypass pressure reducing valve (4) is put into automatic pressure control, the opening degree of the high pressure bypass pressure reducing valve (4) is adjusted according to the main steam pressure detected by the first pressure sensor (26); wherein, the preset first pressure value refers to the main steam pressure value set according to the turbine start-up state.

2. The bypass system control system of the steam turbine unit according to claim 1, characterized in that, Also includes: The third pressure sensor (28) is installed on the reheat steam pipe (18) and located between the boiler (3) and the first low bypass pipe (22).

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