A generator set peak shaving system and control method

Abstract

The application discloses a generator unit peak regulation system, relates to the coal power technology field, and aims to solve the problems of slow response, difficult start of the existing coal power unit peak regulation, and the coupling of multiple units being limited to the same type of units, and the difficulty in realizing the cross-type deep cooperation between the coal units and the combustion units. The application comprises a steam turbine generator unit subsystem which is provided with a large boiler, a high-pressure cylinder, a medium-pressure cylinder and a large feed water pump turbine; a combined cycle unit subsystem which is provided with a gas turbine, a waste heat boiler, a steam turbine and a feed water pump turbine; a steam header; and a feed water coupling pipeline which realizes the water supply of the two-side feed water pump turbines to the opposite boilers. The application further discloses a control method corresponding to the system. The steam header is used to realize the steam mutual aid between the coal units and the combustion units, the feed water coupling pipeline is used to realize the two-way mutual backup of the feed water, and the gas turbine is used to recursively start the steam turbine generator unit under the condition of no external steam, so that the technical problems of slow response and difficult start of the coal power unit peak regulation are solved.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power technology, and more particularly to a generator set peak-shaving system and control method. Background Technology

[0002] With the large-scale grid connection of new energy sources, the peak-valley difference in the power system is widening, making the demand for peak-shaving capacity increasingly urgent. Traditional thermal power units have limited peak-shaving capacity, and frequent peak-shaving can easily lead to increased equipment wear and coal consumption, making it difficult to meet the grid's deep peak-shaving requirements. While the peak-shaving capacity of a single unit is limited, multi-unit coupling can optimize the overall peak-shaving effect through coordinated control. The fast response characteristics of multi-unit coupling can compensate for the slow response of thermal power units, and the overall plant's peak-shaving capacity can be improved through optimized load distribution among multiple units.

[0003] The installed capacity of new energy power generation has grown rapidly and has become an important part of the power system. However, new energy power generation is characterized by intermittency, volatility, and uncertainty. Its large-scale grid connection has led to a continuous increase in the peak-valley difference of the power system, and the demand for peak-shaving capacity of the power grid is becoming increasingly urgent.

[0004] Currently, traditional thermal power units undertake important peak-shaving tasks. However, this existing technology has the following shortcomings: limited peak-shaving capacity of a single unit, slow peak-shaving response speed, frequent peak-shaving leading to increased equipment wear and energy consumption, and lack of deep coordination in multi-unit coupling methods.

[0005] In summary, how to achieve rapid startup, deep peak shaving, and efficient operation of coal-fired power units while ensuring safe operation is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, one of the objectives of the present invention is to provide a generator set peak shaving system, which makes up for the slow response of thermal power units by using the fast response characteristics of multi-unit coupling, and improves the peak shaving capacity of the whole plant by optimizing the load distribution of multi-units.

[0007] One of the objectives of this invention is achieved through the following technical solution: A generator set peak-shaving system includes: The steam turbine generator subsystem includes a large boiler, a high-pressure cylinder, an intermediate-pressure cylinder, and a large feedwater pump turbine. The large boiler is connected to the high-pressure cylinder, and the exhaust port of the high-pressure cylinder is connected to a high-pressure exhaust pipe. The high-pressure exhaust pipe has at least one branch pipe, which is connected to the steam inlet of the first feedwater pump turbine and / or the second feedwater pump turbine through a feedwater pump turbine pipe. The five extraction ports of the intermediate-pressure cylinder are connected to the steam header through five extraction pipes. The combined cycle unit subsystem includes a gas turbine, a waste heat boiler, a first steam turbine, a second steam turbine, a first feedwater pump turbine, and a second feedwater pump turbine. The gas turbine is connected to the waste heat boiler, and the main steam outlet of the waste heat boiler is connected to the first steam turbine, the second steam turbine, and the steam header via a main steam pipeline. The high-pressure extraction port of the first steam turbine is connected to the steam inlet of the first feedwater pump turbine via a first high-pressure extraction pipeline, and the high-pressure extraction port of the second steam turbine is connected to the steam inlet of the second feedwater pump turbine via a second high-pressure extraction pipeline. The steam header has its steam inlet end connected to the five-section extraction steam pipe and the main steam pipe respectively, and its steam outlet end connected to the steam inlet of the first feedwater pump turbine through the seventh pipe, to the steam inlet of the second feedwater pump turbine through the eighth pipe, and to the steam inlet of the large feedwater pump turbine through the ninth pipe. The feedwater coupling pipeline includes: a first outlet pipe of the first feedwater pump turbine and a second outlet pipe of the second feedwater pump turbine, the first outlet pipe and the second outlet pipe being respectively connected to the feedwater inlet of the waste heat boiler and the feedwater inlet of the large boiler; and a third outlet pipe of the large feedwater pump turbine, the third outlet pipe being connected to the feedwater inlet of the waste heat boiler.

[0008] The dual design of "steam header + feedwater coupling" provides a structural foundation for subsequent start-up without external power source, feedwater backup, and switching between multiple steam sources.

[0009] Furthermore, the low-pressure extraction port of the first steam turbine is connected to the steam header via a first low-pressure extraction pipe; the low-pressure extraction port of the second steam turbine is connected to the steam header via a second low-pressure extraction pipe.

[0010] Low-pressure extracted steam can be used as a low-grade heat source for heating or auxiliary drive, realizing the cascade utilization of steam.

[0011] To enable steam exchange between the two steam turbines, avoid system shutdowns, and improve the operational reliability and flexibility of the combined cycle side, a connecting pipe is provided between the first steam turbine and the second steam turbine. A connecting valve is installed on the connecting pipe to control the steam flow between the first steam turbine and the second steam turbine.

[0012] To further avoid wasting steam by venting, achieve heat energy recovery and utilization, and improve overall thermal efficiency, a heating steam box is also included. The steam inlet of the heating steam box is connected to the steam outlet of the steam header, and is used to receive steam and supply heat to the outside.

[0013] In order to enable the system to have the capability of "starting without external steam" and to enable the system to have the capability of self-starting under all operating conditions, the system can use the steam in the steam header to drive the first feedwater pump turbine and / or the second feedwater pump turbine to supply water to the waste heat boiler and start the gas turbine, and use the steam generated by the waste heat boiler to drive the large feedwater pump turbine to supply water to the large boiler through the steam header, so as to start the turbine generator set.

[0014] The second objective of this invention is to provide a control method for a generator set peak shaving system, which first uses residual steam from the steam header to drive the gas turbine-side feedwater pump to start the gas turbine, and then uses the steam generated by the gas turbine to drive the coal-fired turbine-side feedwater pump to start the steam turbine generator set in a non-external recursive start-up control.

[0015] The second objective of this invention is achieved by the following technical solution: A control method for a generator set peak-shaving system includes start-up control: S1: Use the steam in the steam header to drive the first feedwater pump turbine and / or the second feedwater pump turbine to send feedwater into the waste heat boiler along the first outlet pipe and / or the second outlet pipe. S2: Start the gas turbine. The exhaust gas from the gas turbine enters the waste heat boiler to heat the feedwater. The high-temperature steam generated enters the steam header through the main steam pipeline. S3: Use the steam in the steam header to drive the large feedwater pump turbine, and send feedwater into the large boiler along the third outlet pipe; S4: When the feedwater of the large boiler meets the operating conditions, start the steam turbine generator set; S5: When the five-stage extraction steam parameters of the intermediate pressure cylinder meet the set conditions, the steam source of the large feedwater pump turbine is switched to the five-stage extraction steam, and the first feedwater pump turbine, the second feedwater pump turbine, and the gas turbine are stopped.

[0016] To achieve a smooth load transition, avoid significant disturbances, and improve the overall ramp-up rate of the power plant, load ramp-up control is also included: When load demand increases, the gas turbine is started, and the steam generated by the waste heat boiler enters the steam header through the main steam pipeline, driving the first feedwater pump turbine and / or the second feedwater pump turbine to supply water to the waste heat boiler. When the load demand continues to increase, the first steam turbine is started, and the steam generated by the waste heat boiler drives the first steam turbine to do work and generate electricity; when the high-pressure extraction steam parameters of the first steam turbine meet the set conditions, the steam source of the first feedwater pump turbine is switched to the first high-pressure extraction steam pipeline, and the steam header supplies steam to the first feedwater pump turbine through the seventh pipeline as a backup steam source. When the load demand continues to rise, the second steam turbine is started, and the steam generated by the waste heat boiler drives the second steam turbine to generate electricity; when the high-pressure extraction steam parameters of the second steam turbine meet the set conditions, the steam source of the second feedwater pump turbine is switched to the second high-pressure extraction steam pipeline, and the steam header supplies steam to the second feedwater pump turbine through the eighth pipeline as a backup steam source.

[0017] Furthermore, in order to achieve cross-type bidirectional mutual backup of the feedwater system and prevent boiler shutdown due to feedwater pump turbine failure, it also includes feedwater mutual backup control: When the large feedwater pump turbine fails, the first feedwater pump turbine and / or the second feedwater pump turbine are started to supply water to the large boiler through the first outlet pipe and / or the second outlet pipe. When the first feedwater pump turbine and / or the second feedwater pump turbine fail, the large feedwater pump turbine is started, and water is supplied to the waste heat boiler through the third outlet pipe.

[0018] To ensure continuous operation of the feedwater pump turbine and improve reliability under all operating conditions, steam source switching control is also included: When the steam source of the large feedwater pump turbine is insufficient or malfunctions, steam is supplied to the large feedwater pump turbine through the steam header and the ninth pipeline, or through the waste heat boiler and the branch steam pipeline. When the steam source of the first feedwater pump turbine fails, steam is supplied to the first feedwater pump turbine through the steam header and the seventh pipeline, or through the high-pressure exhaust pipeline and the feedwater pump turbine pipeline, or through the connecting pipe and the connecting valve. When the steam source of the second feedwater pump turbine fails, steam is supplied to the second feedwater pump turbine through the steam header and the eighth pipeline, or steam is supplied to the second feedwater pump turbine through the high-pressure exhaust pipeline and the feedwater pump turbine pipeline.

[0019] Furthermore, when the waste heat boiler generates excess steam or the steam pressure exceeds a set threshold, the excess steam is introduced into the heating steam box via the steam header for external heating.

[0020] This not only prevents the system from tripping due to overpressure, but also avoids the waste of high-quality steam by venting it out, thus improving energy efficiency.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention couples large coal-fired power units with gas-fired combined cycle units via a steam header. The rapid start-up and flexible adjustment of the gas turbine compensate for the slow peak-shaving response of the coal-fired power units, achieving complementary advantages between the two types of units and significantly improving the plant's overall peak-shaving capacity. The steam header collects extraction steam from the fifth stage of the coal-fired power unit and main steam from the waste heat boiler, allowing for flexible steam distribution to the feedwater pump turbines on both sides. When steam parameters on one side fluctuate or are insufficient, steam from the other side can be replenished promptly, solving the problem of unstable feedwater pump turbine steam supply under deep peak-shaving conditions. The first / second feedwater pump turbines can supply water to the large boiler, and the large feedwater pump turbine can supply water to the waste heat boiler. When either feedwater pump turbine fails, the other side can supply water to its boiler across the system, preventing unplanned unit shutdowns due to feedwater interruptions. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the generator set peak-shaving system of the present invention; Figure 2 This is a flowchart of the control method for the generator set peak-shaving system in Example 2.

[0023] In the diagram: 1. Gas turbine; 2. Waste heat boiler; 2-1. Main steam pipeline; 2-4. Branch steam pipeline; 3. First steam turbine; 3-1. First high-pressure extraction steam pipeline; 3-2. First low-pressure extraction steam pipeline; 3-3. Connecting pipe; 3-4. Connecting valve; 4. Second steam turbine; 4-1. Second high-pressure extraction steam pipeline; 4-2. Second low-pressure extraction steam pipeline; 5. First feedwater pump turbine; 5-1. First outlet water pipeline; 6. Second feedwater pump. Steam turbine; 6-1, Second outlet water pipe; 7, Steam header; 7-1, Seventh pipe; 7-2, Eighth pipe; 7-3, Ninth pipe; 8, Heating steam box; 9, Large boiler; 10, High-pressure cylinder; 10-1, High-pressure exhaust pipe; 10-2, Feedwater pump turbine pipe; 11, Intermediate-pressure cylinder; 11-1, Five-stage extraction steam pipe; 12, Large feedwater pump turbine; 12-1, Third outlet water pipe; 12-2, Water pipe to waste heat boiler. Detailed Implementation

[0024] The present invention will now be described in more detail with reference to the accompanying drawings. It should be noted that the following description of the present invention with reference to the accompanying drawings is merely illustrative and not restrictive. Various embodiments can be combined with each other to form other embodiments not shown in the following description.

[0025] Example 1 Example 1 provides a generator set peak shaving system, which aims to build an organic and collaborative ecosystem that deeply binds coal-fired power units and gas turbines through mutual assistance of steam headers, bidirectional mutual backup of feedwater, non-external source recursive start-up, stepped loading, and multi-path steam source redundancy. This solves the technical problems of slow peak shaving response, difficult start-up, unstable auxiliary steam source, and high risk of feedwater interruption in traditional coal-fired power units, and achieves safe, fast, and flexible peak shaving under all operating conditions.

[0026] Please refer to Figure 1 As shown, this embodiment mainly includes the following systems: a steam turbine generator set subsystem and a combined cycle unit subsystem. Specifically, the steam turbine generator set subsystem includes a large boiler 9, a high-pressure cylinder 10, an intermediate-pressure cylinder 11, and a large feedwater pump turbine 12. The large boiler 9 is connected to the high-pressure cylinder 10. The exhaust port of the high-pressure cylinder 10 is connected to the high-pressure exhaust pipe 10-1. The high-pressure exhaust pipe 10-1 has at least one branch pipe, which is connected to the steam inlet of the first feedwater pump turbine 5 and / or the second feedwater pump turbine 6 through the feedwater pump turbine pipe 10-2. Another branch pipe enters the 2-1 main steam pipe to supply steam to the two small steam turbines. The five-stage extraction port of the intermediate-pressure cylinder 11 is connected to the steam header 7 through the five-stage extraction pipe 11-1. The combined cycle unit subsystem includes a gas turbine 1, a waste heat boiler 2, a first steam turbine 3, a second steam turbine 4, a first feedwater pump turbine 5, and a second feedwater pump turbine 6. The gas turbine 1 is connected to the waste heat boiler 2. The main steam outlet of the waste heat boiler 2 is connected to the first steam turbine 3, the second steam turbine 4, and the steam header 7 via a main steam pipe 2-1. The high-pressure extraction port of the first steam turbine 3 is connected to the steam inlet of the first feedwater pump turbine 5 via a first high-pressure extraction pipe 3-1, and the high-pressure extraction port of the second steam turbine 4 is connected to the steam inlet of the second feedwater pump turbine 6 via a second high-pressure extraction pipe 4-1. The steam header 7 has its steam inlet connected to the five-section extraction steam pipe 11-1 and the main steam pipe 2-1, respectively. Its steam outlet is connected to the steam inlet of the first feedwater pump turbine 5 via the seventh pipe 7-1, to the steam inlet of the second feedwater pump turbine 6 via the eighth pipe 7-2, and to the steam inlet of the large feedwater pump turbine 12 via the ninth pipe 7-3. The seventh pipe 7-1 and the eighth pipe 7-2 are two paths leading out of the steam header 7, one to the turbine and the other to the feedwater pump turbine 6.

[0027] It should be noted that the seventh pipe 7-1 is the first branch pipe from the steam header 7 of the equipment. The equipment number "7" is combined with "pipeline" to form the name "seventh pipe", which is not the seventh pipe. The same applies to the other pipe numbers.

[0028] The low-pressure extraction port of the first steam turbine 3 is connected to the steam header 7 via a first low-pressure extraction pipe 3-2; the low-pressure extraction port of the second steam turbine 4 is connected to the steam header 7 via a second low-pressure extraction pipe 4-2. The purpose of the first low-pressure extraction pipe 3-2 and the second low-pressure extraction pipe 4-2 entering the steam header is for heating; after the low-pressure extracted steam enters the steam header 7, it can be used as a low-grade heat source and introduced into the heating steam box through the steam header 7 for external heating, realizing the cascade utilization of energy.

[0029] The water supply coupling pipeline includes: a first outlet pipe 5-1 of the first feedwater pump turbine 5 and a second outlet pipe 6-1 of the second feedwater pump turbine 6, the first outlet pipe 5-1 and the second outlet pipe 6-1 being connected to the feedwater inlet of the waste heat boiler 2 and the feedwater inlet of the large boiler 9, respectively; and a third outlet pipe 12-1 of the large feedwater pump turbine 12, the third outlet pipe 12-1 being connected to the feedwater inlet of the waste heat boiler 2, wherein the first outlet pipe 5-1 and the second outlet pipe 6-1 are branch pipe structures.

[0030] Furthermore, a connecting pipe 3-3 is provided between the first steam turbine 3 and the second steam turbine 4, and a connecting valve 3-4 is provided on the connecting pipe 3-3 to control the steam flow between the first steam turbine 3 and the second steam turbine 4. When the steam source of the first feedwater pump turbine 5 fails, steam can be drawn from the second steam turbine 4 through the connecting valve 3-4 and enter the first feedwater pump turbine 5 through the connecting pipe 3-3. Steam can be exchanged between the two steam turbines through the connecting pipe 3-3, so that when one steam turbine fails or is under maintenance, the other can provide steam support.

[0031] It also includes a heating steam box 8, whose steam inlet is connected to the steam outlet of the steam header 7, for receiving steam and providing heat to the outside. After entering the steam header 7, a portion of the steam enters the heating steam box 8 for heating. During startup and shutdown, if there is excessive steam from the waste heat boiler 2, to ensure unit safety, a portion of the steam enters the heating steam box 8 after entering the steam header 7 for heating. During unit operation, if problems such as excessive steam pressure occur, the steam is piped into the steam header 7 and then into the heating steam box 8 to prevent the unit from tripping due to high pressure.

[0032] In summary, the heating steam box 8 in this embodiment has three functions: Safety valve function during startup / shutdown: When there is too much steam from the waste heat boiler, the excess steam is introduced into the heating steam box 8 to ensure the safety of the unit.

[0033] Overpressure protection function during normal operation: When the steam pressure is too high, it enters the heating steam box 8 through the steam header 7 to avoid tripping due to high pressure.

[0034] External heating function: Receives steam and provides heat to the outside world.

[0035] The system is designed to use steam from the steam header 7 to drive the first feedwater pump turbine 5 and / or the second feedwater pump turbine 6 to supply water to the waste heat boiler 2, start the gas turbine 1, and use steam generated by the waste heat boiler 2 to drive the large feedwater pump turbine 12 to supply water to the large boiler 9 via the steam header 7, thereby starting the turbine generator set.

[0036] The aforementioned "no external steam source" corresponds to a special operating condition after a plant-wide overhaul. In this case, there is no steam source from adjacent units, the boiler is not started, and only residual steam remains in steam header 7. The steam in steam header 7 is the residual steam after the system shutdown.

[0037] The complete startup process chain is as follows: residual steam from the steam header → driving the first feedwater pump turbine 5 / second feedwater pump turbine 6 → supplying water to the waste heat boiler → starting the gas turbine 1 → generating steam in the waste heat boiler → steam entering the steam header 7 → driving the large feedwater pump turbine 12 → supplying water to the large boiler 9 → starting the turbine generator set. After successful startup, a steam source switch must be completed—the large feedwater pump turbine 12 switches from "steam header supply" to "five-stage extraction steam self-supply," and then the gas turbine and the first feedwater pump turbine 5 / second feedwater pump turbine 6 are shut down, and the system enters normal operation.

[0038] Example 2 Example 2 is an explanation of the control logic based on the system in Example 1.

[0039] Please refer to Figure 2 As shown, a control method for a generator set peak-shaving system includes start-up control: S1: Using the steam in the steam header 7 to drive the first feedwater pump turbine 5 and / or the second feedwater pump turbine 6, feedwater is sent into the waste heat boiler 2 along the first outlet pipe 5-1 and / or the second outlet pipe 6-1. During the initial startup phase, steam from the steam header 7 simultaneously or selectively drives the first feedwater pump turbine 5 and / or the second feedwater pump turbine 6 to supply water to the waste heat boiler 2.

[0040] It should be noted that the steam header 7 can be selected as an industrial steam storage tank in actual use, so as to store steam for a long time, from a few hours to a few days.

[0041] S2: Start the gas turbine 1. The exhaust gas from the gas turbine 1 enters the waste heat boiler 2 to heat the feedwater. The high-temperature steam generated enters the steam header 7 through the main steam pipeline 2-1. S3: Use the steam in the steam header 7 to drive the large feedwater pump turbine 12, and send feedwater into the large boiler 9 along the third outlet pipe 12-1; In S3, "using the steam in the steam header 7 to drive the large feedwater pump turbine 12" is achieved through the ninth pipe 7-3. The steam supply path is: steam header 7 → ninth pipe 7-3 → large feedwater pump turbine 12.

[0042] After the gas turbine 1 starts, the steam generated continuously replenishes the steam header 7, ensuring that there is enough steam in the header to drive the large feedwater pump turbine 12 and continue to supply steam (standby) to the first feedwater pump turbine 5 and the second feedwater pump turbine 6.

[0043] S4: When the feedwater of the large boiler 9 meets the operating conditions, start the steam turbine generator set; Before starting the steam turbine generator set, the steam generated by the waste heat boiler 2 must be used to supply steam to the shaft seal and purge the steam turbine set. The turbine can be officially started after the shaft seal steam parameters meet the requirements.

[0044] S5: When the five-stage extraction steam parameters of the intermediate pressure cylinder 11 meet the set conditions, the steam source of the large feedwater pump turbine 12 is switched to the five-stage extraction steam, and the first feedwater pump turbine 5, the second feedwater pump turbine 6 and the gas turbine 1 are stopped.

[0045] The settings for S4 and S5 are usually pre-set at the factory for boilers and steam turbines, so this embodiment does not limit the specific settings.

[0046] When the parameters of the fifth-stage extraction steam in the intermediate pressure cylinder 11, such as temperature and pressure, meet the requirements, the steam source of the large feedwater pump turbine 12 is switched to the fifth-stage extraction steam. Subsequently, the first feedwater pump turbine 5 and the second feedwater pump turbine 6 are shut down, followed by the shutdown of the gas turbine 1. It also includes load increase control: When the load demand increases, the gas turbine 1 is started, and the steam generated by the waste heat boiler 2 enters the steam header 7 through the main steam pipeline 2-1, driving the first feedwater pump turbine 5 and / or the second feedwater pump turbine 6 to supply water to the waste heat boiler 2. When the load demand continues to increase, the first steam turbine 3 is started, and the steam generated by the waste heat boiler 2 drives the first steam turbine 3 to generate electricity; when the high-pressure extraction steam parameters of the first steam turbine 3 meet the set conditions, the steam source of the first feedwater pump turbine 5 is switched to the first high-pressure extraction steam pipeline 3-1, and the steam header 7 supplies steam to the first feedwater pump turbine 5 through the seventh pipeline 7-1 as a backup steam source. In addition, when the steam parameters are qualified, for example, when the steam temperature reaches 250℃ and the pressure is greater than 1 MPa, the first high-pressure extraction steam pipeline 3-1 supplies steam to the first feedwater pump turbine 5. Steam supply to the feedwater pump turbine is interrupted by the seventh pipeline 7-1, and is only provided when parameters fluctuate to ensure the steam source pressure. The first low-pressure extraction steam pipeline 3-2 enters the steam header 7, where it is partially used for heating.

[0047] When the load demand continues to rise, the second steam turbine 4 is started. The steam generated by the waste heat boiler 2 drives the second steam turbine 4 to generate electricity. When the high-pressure extraction steam parameters of the second steam turbine 4 meet the set conditions, the steam source of the second feedwater pump turbine 6 is switched to the second high-pressure extraction steam pipeline 4-1. The steam header 7 supplies steam to the second feedwater pump turbine 6 through the eighth pipeline 7-2 as a backup steam source.

[0048] When the steam parameters are qualified, for example, the steam temperature can be set to be greater than 300℃ and the pressure greater than 1.5 MPa, the second high-pressure extraction steam pipeline 4-1 supplies steam to the second feedwater pump turbine 6. Steam supply to the second feedwater pump turbine 6 via the eighth pipeline 7-2 is interrupted, only supplying steam when parameters fluctuate to ensure the steam source pressure. The second low-pressure extraction steam pipeline 4-2 enters the steam header 7, partially for heating.

[0049] It should be noted that the above startup sequence cannot be skipped to ensure a smooth load transition and avoid impacting the power grid.

[0050] After the switching process is completed, the feedwater pump turbine pipeline 10-2 (high-pressure exhaust pipeline) still serves as a supplementary backup steam source for the first / second feedwater pump turbines 5 and 6. When the parameters of the steam header 7 are insufficient, the high-pressure exhaust steam can drive the feedwater pump turbine through the feedwater pump turbine pipeline 10-2.

[0051] It also includes water supply backup control: When the large feedwater pump turbine 12 fails, the first feedwater pump turbine 5 and / or the second feedwater pump turbine 6 are started to supply water to the large boiler 9 through the first outlet pipe 5-1 and / or the second outlet pipe 6-1. When the first feedwater pump turbine 5 and / or the second feedwater pump turbine 6 fail, the large feedwater pump turbine 12 is started, and water is supplied to the waste heat boiler 2 through the third outlet pipe 12-1.

[0052] The first outlet pipe 5-1 splits into two routes: one goes to waste heat boiler 2, and the other (to the large boiler water pipe 5-2) goes to large boiler 9. When the large feedwater pump turbine 12 fails, feedwater is supplied to large boiler 9 via both pipes. Similarly, when the first / second feedwater pump turbines 5 and 6 fail, the path for supplying water to waste heat boiler 2 is to waste heat boiler water pipe 12-2, which is a branch of the third outlet pipe 12-1. The third outlet pipe 12-1 splits into two routes: one goes to large boiler 9, and the other goes to waste heat boiler. When the feedwater pump turbine fails, feedwater is supplied to waste heat boiler 9 via the third outlet pipe 12-1 → waste heat boiler water pipe 12-2.

[0053] If only one of the first feedwater pump turbine 5 and the second feedwater pump turbine 6 fails, while the other is still operating normally, the operating turbine can continue to supply water to the waste heat boiler 9. At the same time, the large feedwater pump turbine 12 provides supplementary feedwater to the waste heat boiler 9 through the waste heat boiler water pipeline 12-2.

[0054] Logic of steam source switching control: When the steam source of the large feedwater pump turbine 12 is insufficient or malfunctions, steam is supplied to the large feedwater pump turbine 12 through the steam header 7 and the ninth pipeline 7-3, or through the waste heat boiler 2 and the branch steam pipeline 2-4 (to the large feedwater pump turbine pipeline) to the large feedwater pump turbine 12. When the steam source of the first feedwater pump turbine 5 fails, steam is supplied to the first feedwater pump turbine 5 through the steam header 7 and the seventh pipeline 7-1, or through the high-pressure exhaust pipeline 10-1 and the feedwater pump turbine pipeline 10-2, or through the connecting pipe 3-3 and the connecting valve 3-4. When the steam source for the second feedwater pump turbine 6 fails, steam is supplied to the second feedwater pump turbine 6 via the steam header 7 and the eighth pipeline 7-2, or via the high-pressure exhaust pipeline 10-1 and the feedwater pump turbine pipeline 10-2. This startup process is activated not only when the steam source for the first / second feedwater pump turbines 5 and 6 fails, but also when the parameters of the steam header 7 are insufficient.

[0055] The two supplementary steam source paths for the large feedwater pump turbine 12 are: steam header 7 via the ninth pipe 7-3 and waste heat boiler 2 via branch steam pipe 2-4. These two paths can be used individually or simultaneously, depending on the operating conditions.

[0056] The path of the connecting valve 3-4 is as follows: steam enters the first feedwater pump turbine 5, that is, steam is drawn from the second feedwater pump turbine 6 side through the connecting pipe 3-3, and enters the first feedwater pump turbine 5 through the connecting valve 3-4. Similarly, the three paths of the second feedwater pump turbine 6 are basically the same as the path 5 of the first feedwater pump turbine, and will not be described again in this embodiment.

[0057] When the waste heat boiler 2 generates excess steam or the steam pressure exceeds a set threshold, for example, when the waste heat boiler pressure is greater than 6 MPa, the excess steam is introduced into the heating steam box 8 through the steam header 7 for external heating.

[0058] The excess steam treatment in the aforementioned heating steam box 8 has three functions: Excess steam handling during startup / shutdown: When the waste heat boiler 2 generates too much steam, the excess steam is introduced into the heating steam box 7.

[0059] Utilization of excess steam during normal operation: When the steam turbine generator set is running stably, the steam extracted from the fifth stage enters the steam header 7 and is then partially introduced into the heating steam box 8.

[0060] Overpressure protection function: When the steam pressure is too high during unit operation, the steam is introduced into the heating steam box 8 through the steam header 7 to avoid unit tripping.

[0061] In addition, after the steam enters the heating steam box 8, it is supplied to heat users through the external heating pipeline.

[0062] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A generator set peak-shaving system, characterized in that, include: The steam turbine generator subsystem includes a large boiler (9), a high-pressure cylinder (10), an intermediate-pressure cylinder (11), and a large feedwater pump turbine (12); the large boiler (9) is connected to the high-pressure cylinder (10), the exhaust port of the high-pressure cylinder (10) is connected to a high-pressure exhaust pipe (10-1), the high-pressure exhaust pipe (10-1) has at least one branch pipe, which is connected to the steam inlet of the first feedwater pump turbine (5) and / or the second feedwater pump turbine (6) through the feedwater pump turbine pipe (10-2), and the five extraction ports of the intermediate-pressure cylinder (11) are connected to the steam header (7) through the five extraction pipes (11-1); The combined cycle unit subsystem includes a gas turbine (1), a waste heat boiler (2), a first steam turbine (3), a second steam turbine (4), a first feedwater pump turbine (5), and a second feedwater pump turbine (6); the gas turbine (1) is connected to the waste heat boiler (2), and the main steam outlet of the waste heat boiler (2) is connected to the first steam turbine (3), the second steam turbine (4), and the steam header (7) respectively through the main steam pipeline (2-1); the high-pressure extraction port of the first steam turbine (3) is connected to the steam inlet of the first feedwater pump turbine (5) through the first high-pressure extraction pipeline (3-1), and the high-pressure extraction port of the second steam turbine (4) is connected to the steam inlet of the second feedwater pump turbine (6) through the second high-pressure extraction pipeline (4-1); The steam header (7) is connected at its steam inlet to the five-section extraction steam pipe (11-1) and the main steam pipe (2-1), respectively. Its steam outlet is connected to the steam inlet of the first feedwater pump turbine (5) through the seventh pipe (7-1), to the steam inlet of the second feedwater pump turbine (6) through the eighth pipe (7-2), and to the steam inlet of the large feedwater pump turbine (12) through the ninth pipe (7-3). The water supply coupling pipeline includes: a first outlet pipe (5-1) of the first water supply pump turbine (5) and a second outlet pipe (6-1) of the second water supply pump turbine (6), the first outlet pipe (5-1) and the second outlet pipe (6-1) being connected to the water supply inlet of the waste heat boiler (2) and the water supply inlet of the large boiler (9), respectively; and a third outlet pipe (12-1) of the large water supply pump turbine (12), the third outlet pipe (12-1) being connected to the water supply inlet of the waste heat boiler (2).

2. The generator set peak-shaving system as described in claim 1, characterized in that, The low-pressure extraction port of the first steam turbine (3) is connected to the steam header (7) through the first low-pressure extraction pipe (3-2); the low-pressure extraction port of the second steam turbine (4) is connected to the steam header (7) through the second low-pressure extraction pipe (4-2).

3. The generator set peak-shaving system as described in claim 1, characterized in that, A connecting pipe (3-3) is provided between the first steam turbine (3) and the second steam turbine (4), and a connecting valve (3-4) is provided on the connecting pipe (3-3) to control the steam flow between the first steam turbine (3) and the second steam turbine (4).

4. The generator set peak-shaving system as described in claim 1, characterized in that, It also includes a heating steam box (8), the steam inlet of which is connected to the steam outlet of the steam header (7), for receiving steam and supplying heat to the outside.

5. The generator set peak-shaving system as described in claim 1, characterized in that, The system can use the steam in the steam header (7) to drive the first feedwater pump turbine (5) and / or the second feedwater pump turbine (6) to supply water to the waste heat boiler (2) and start the gas turbine (1) under the condition of no external steam source. It can also use the steam generated by the waste heat boiler (2) to drive the large feedwater pump turbine (12) to supply water to the large boiler (9) through the steam header (7) to start the steam turbine generator set.

6. A control method for a generator set peak-shaving system, characterized in that, Including startup control: S1: Use the steam in the steam header (7) to drive the first feedwater pump turbine (5) and / or the second feedwater pump turbine (6) to send feedwater into the waste heat boiler (2) along the first outlet pipe (5-1) and / or the second outlet pipe (6-1); S2: Start the gas turbine (1), the exhaust gas of the gas turbine (1) enters the waste heat boiler (2) to heat the feed water, and the generated high-temperature steam enters the steam header (7) through the main steam pipeline (2-1). S3: Use the steam in the steam header (7) to drive the large feedwater pump turbine (12) to send feedwater into the large boiler (9) along the third outlet pipe (12-1); S4: When the feedwater of the large boiler (9) meets the operating conditions, start the steam turbine generator set; S5: When the five-stage extraction steam parameters of the intermediate pressure cylinder (11) meet the set conditions, the steam source of the large feedwater pump turbine (12) is switched to the five-stage extraction steam, and the first feedwater pump turbine (5), the second feedwater pump turbine (6) and the gas turbine (1) are stopped.

7. The control method for a generator set peak-shaving system as described in claim 6, characterized in that, It also includes load increase control: When the load demand increases, the gas turbine (1) is started, and the steam generated by the waste heat boiler (2) enters the steam header (7) through the main steam pipeline (2-1), driving the first feedwater pump turbine (5) and / or the second feedwater pump turbine (6) to supply water to the waste heat boiler (2); When the load demand continues to increase, the first steam turbine (3) is started, and the steam generated by the waste heat boiler (2) drives the first steam turbine (3) to do work and generate electricity; when the high pressure extraction parameters of the first steam turbine (3) meet the set conditions, the steam source of the first feedwater pump turbine (5) is switched to the first high pressure extraction pipeline (3-1), and the steam header (7) supplies steam to the first feedwater pump turbine (5) through the seventh pipeline (7-1) as a backup steam source; When the load demand continues to rise, the second steam turbine (4) is started. The steam generated by the waste heat boiler (2) drives the second steam turbine (4) to generate electricity. When the high-pressure extraction steam parameters of the second steam turbine (4) meet the set conditions, the steam source of the second feedwater pump turbine (6) is switched to the second high-pressure extraction steam pipeline (4-1). The steam header (7) supplies steam to the second feedwater pump turbine (6) through the eighth pipeline (7-2) as a backup steam source.

8. The control method for a generator set peak-shaving system as described in claim 6, characterized in that, It also includes water supply backup control: When the large feedwater pump turbine (12) fails, the first feedwater pump turbine (5) and / or the second feedwater pump turbine (6) are started to supply water to the large boiler (9) through the first outlet pipe (5-1) and / or the second outlet pipe (6-1); When the first feedwater pump turbine (5) and / or the second feedwater pump turbine (6) fail, the large feedwater pump turbine (12) is started to supply water to the waste heat boiler (2) through the third outlet pipe (12-1).

9. The control method for a generator set peak-shaving system as described in claim 6, characterized in that, It also includes steam source switching control: When the steam source of the large feedwater pump turbine (12) is insufficient or malfunctions, steam is supplied to the large feedwater pump turbine (12) through the steam header (7) via the ninth pipeline (7-3), or steam is supplied to the large feedwater pump turbine (12) through the waste heat boiler (2) via the branch steam pipeline (2-4). When the steam source of the first feedwater pump turbine (5) fails, steam is supplied to the first feedwater pump turbine (5) through the steam header (7) via the seventh pipeline (7-1), or through the high-pressure exhaust pipeline (10-1) via the feedwater pump turbine pipeline (10-2), or through the connecting pipe (3-3) via the connecting valve (3-4); When the steam source of the second feedwater pump turbine (6) fails, steam is supplied to the second feedwater pump turbine (6) through the steam header (7) via the eighth pipeline (7-2), or steam is supplied to the second feedwater pump turbine (6) through the high-pressure exhaust pipeline (10-1) via the feedwater pump turbine pipeline (10-2).

10. The control method for a generator set peak-shaving system as described in claim 6, characterized in that, When the waste heat boiler (2) generates excess steam or the steam pressure exceeds the set threshold, the excess steam is introduced into the heating steam box (8) through the steam header (7) for external heating.

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