A multi-unit coupled peak shaving and frequency modulation system and method

Abstract

The application belongs to the field of electric power, and discloses a multi-unit coupled peak regulation and frequency modulation system and method, which comprises the following steps: a coupling architecture is constructed, which comprises a high-pressure cylinder separate power generation system, a high-medium-pressure cylinder power generation system, a water system and a vacuum system, and the steam, feed water, condensate water and vacuum passage of each system can be flexibly switched according to the state of the power grid load, so that deep peak regulation and rapid frequency modulation are realized under the premise of ensuring the safety of the unit.

Description

Technical Field

[0001] This invention belongs to the field of power, and in particular relates to a peak-shaving and frequency regulation system and method for coupling multiple generating units. Background Technology

[0002] During peak periods when wind and solar power resources are abundant, coal-fired power units need to proactively reduce their output and make room for grid connection to ensure that clean electricity is fully connected to the grid and consumed. When extreme weather causes a sharp drop in the output of new energy sources, or when there is a power shortage during peak electricity load periods, coal-fired power units need to quickly start up and make up for the peak load through minute-level or even second-level response to promptly smooth out power fluctuations in the grid.

[0003] Currently, coal-carrying power units adopt a single high-pressure cylinder configuration. Under this configuration, the unit has problems such as low regulation rate and small adjustable load range during the load regulation phase. When the grid load fluctuates rapidly, the unit's own regulation performance cannot meet the grid's real-time response requirements. Summary of the Invention

[0004] In view of this, the present invention discloses a peak-shaving and frequency regulation system and method for coupling multiple generating units, which can solve the shortcomings of related technologies.

[0005] To achieve the above objectives, the present invention discloses the following technical solution: According to a first aspect of the present invention, a peak-shaving and frequency regulation system with multiple units coupled is proposed, including a high-pressure cylinder separate power generation system, an intermediate-high-pressure cylinder power generation system, a water system, a vacuum system, and a heating system; The high-pressure cylinder separate power generation system includes a boiler 0, a first high-pressure cylinder 1, a second high-pressure cylinder 2, a generator 1-1, a reheater 2-4, and a steam header 12; the main steam generated by the boiler 0 is divided into two paths, which are sent to the first high-pressure cylinder 1 through the first high-pressure cylinder steam pipe 0-1 and to the second high-pressure cylinder 2 through the second high-pressure cylinder steam pipe 0-2, respectively. The exhaust steam from the first high-pressure cylinder 1 is divided into three paths: one path is sent to the steam header 12 and the first condenser 10 via the first steam pipeline 1-4, another path is sent to the first high-pressure heater 4, and the third path is sent to the reheater 2-4; the second-stage extraction steam 1-3 from the first high-pressure cylinder 1 is sent to the second high-pressure heater 5. The exhaust steam from the second high-pressure cylinder 2 is divided into three paths: one path is sent to the first high-pressure heater 4, one path is sent to the second condenser 11, and one path is sent to the steam header 12; the second-stage extraction steam 2-3 from the second high-pressure cylinder 2 is sent to the second high-pressure heater 5; the steam from the outlet of the reheater 2-4 is sent to the intermediate-pressure cylinder 3. The water system includes a first high-pressure heater 4, a second high-pressure heater 5, a third high-pressure heater 6, a deaerator 7, a feedwater pump turbine 8, and a feedwater pump 9. A portion of the steam from the steam header 12 is fed into the feedwater pump turbine 8 to drive the feedwater pump 9, and a portion of the fourth-stage extraction steam is also fed into the feedwater pump turbine 8. The steam from the steam header 12 is also fed into the deaerator 7 to heat the feedwater. The feedwater from the outlet of the feedwater pump 9 is divided into two paths: one path returns to the boiler 0 via the high-pressure heater system, and the other path is fed into the steam header 12 to regulate the steam temperature. The vacuum system includes a first condenser 10, a second condenser 11, and a steam connecting pipe 11-1 connecting the two. The exhaust steam from the feedwater pump turbine 8-1 and the exhaust steam from the high-pressure cylinder can be selectively sent to either the first condenser 10 or the second condenser 11, with the two condensers serving as backups for each other. The condensate from the second condenser 11 is sent to the deaerator 7 via the condensate pipe 11-2. The heating system includes a steam desuperheating device 13, a steam cooler 14, a heat exchanger 15, and a hot water tank 16. The four-stage extraction steam 3-3 of the intermediate pressure cylinder 3 is combined with the heating steam of the steam header 12. One path is desuperheated and depressurized by the steam desuperheating device 13 to supply high-temperature steam to the outside, and the other path is cooled by the steam cooler 14 and sent to the heat exchanger 15 to exchange heat with condensate. The hot water after heat exchange and the condensate after steam cooling are both sent to the hot water tank 16. The water in the hot water tank 16 is used for external heating and is also sent to the boiler 0 as emergency makeup water.

[0006] Preferably, the three-stage extraction steam 3-1 of the intermediate pressure cylinder 3 is sent to the third high-pressure heater 6, the four-stage extraction steam 3-2 serves as the normal heating steam source for the deaerator 7, and the steam from the steam header 12 serves as the backup heating steam source for the deaerator 7; when the pressure of the four-stage extraction steam is lower than the set threshold, the steam supply is automatically switched to the steam header 12.

[0007] Preferably, the steam source of the feedwater pump turbine 8 has an automatic switching logic: during normal operation, the fourth-stage extraction steam 3-2 is used as the main steam source, and the steam from the steam header 12 is used as the backup steam source; when the pressure of the fourth-stage extraction steam is insufficient, the temperature is abnormal, or the feedwater pump turbine malfunctions, the steam source is switched to the steam header 12 within 10 seconds to ensure the continuous operation of the feedwater pump.

[0008] Preferably, the first condenser 10 and the second condenser 11 are connected on the steam side through a steam connecting pipe 11-1. The exhaust steam from the high-pressure cylinder and the exhaust steam from the feedwater pump turbine can be freely switched to either condenser through valves. When the vacuum degree of a single condenser is lower than the set value or a fault occurs, all exhaust steam can be switched to another condenser within 30 seconds to avoid unit tripping.

[0009] Preferably, an emergency water supply pipeline is provided between the hot water tank 16 and the boiler 0, and a quick-closing regulating valve is configured on the pipeline; when the unit experiences a feedwater temperature lower than the set value, insufficient feedwater flow, feedwater pump steam source failure, or condenser vacuum abnormality, the quick-closing regulating valve opens within 5 seconds, and the high-temperature water in the hot water tank 16 quickly supplies water to the boiler, and the water supply flow can cover 30% to 100% of the boiler's rated feedwater.

[0010] Preferably, the desuperheating water of the steam cooler 14 comes from the condensate pipe 11-2 of the second condenser 11, and the flow rate of the desuperheating water is automatically adjusted according to the steam outlet temperature of the steam cooler; the condensate after heat exchange is sent to the hot water tank 16, mixed with the condensate after steam cooling and stored, and the water temperature of the hot water tank is maintained at 80~120℃.

[0011] Preferably, the system is configured with three operating modes for off-peak grid load conditions: High and medium pressure unit maintenance mode: Only the first high pressure cylinder 1 is running. Its exhaust steam enters the steam desuperheating device 13 for heating through the reheater bypass. Part of the exhaust steam is sent to the steam header 12 for deaerator heating and feedwater pump turbine drive. Part of the water output from the feedwater pump 9 is sent to the steam header 12 for cooling. The hot water tank 16 serves as the boiler emergency water supply. Maintenance mode of single high-pressure cylinder unit: Only the high-pressure unit consisting of the second high-pressure cylinder 2 and the intermediate-pressure cylinder 3 is in operation. The exhaust steam of the second high-pressure cylinder enters the reheater 2-4 and is then sent to the intermediate-pressure cylinder 3 to do work. When the load is ≥50%, the extraction steam of each section is put into operation. The steam source of the feedwater pump turbine and deaerator is switched to the four-stage extraction steam. The steam in the steam header 12 is mainly used for heating. Dual-unit operation mode: The first high-pressure cylinder 1 and the second high-pressure cylinder 2 operate simultaneously. After the exhaust steam from the two cylinders merges, it enters the reheater 2-4 and is sent to the intermediate-pressure cylinder 3 to do work. Steam extraction is put into operation throughout the entire section. Steam from the steam header 12 is used as a heating and backup steam source. Overpressure steam enters the steam desuperheating device 13 through the bypass to relieve pressure.

[0012] Furthermore, the rapid adjustment logic under the condition of sudden load drop in the power grid is as follows: First-level load reduction: Cut off the steam inlet of the first high-pressure cylinder steam pipe 0-1, the first high-pressure cylinder 1 enters the rotating standby state, and all its exhaust steam is sent to the condenser. Cut off the relevant extraction steam of the first high-pressure cylinder. The load adjustment rate can reach 3%~5%Pe / min. Secondary load reduction: Based on the primary load reduction, the steam inlet of the second high-pressure cylinder steam pipe 0-2 is cut off, the second high-pressure cylinder 2 is shut down, and all its exhaust steam is sent to the condenser. All extraction steam from the second high-pressure cylinder and the intermediate-pressure cylinder is cut off, and the steam source of the feedwater pump turbine is switched to the steam header 12. The load regulation rate can reach 5%~8%Pe / min.

[0013] According to a second aspect of the present invention, a peak-shaving and frequency-regulating method for multi-unit coupling is proposed, based on the system described in any one of the preceding first aspects, characterized in that it comprises: When the power grid dispatch command requires a load ramp rate of ≥3%Pe / min, the first high-pressure cylinder 1 and the second high-pressure cylinder 2 are started to simultaneously introduce steam, and all extraction steam valves are fully opened to switch the steam source of the feedwater pump turbine to four-stage extraction steam. At the same time, the emergency water supply pipeline from the hot water tank 16 to the boiler is opened to supply water to the boiler at 50%~100% of the rated flow rate, thereby increasing the boiler evaporation rate and achieving rapid load ramp-up. When the power grid dispatching command requires a load reduction rate of ≥3%Pe / min, the main steam valve is closed in the order of first cutting off the steam inlet of the first high-pressure cylinder and then cutting off the steam inlet of the second high-pressure cylinder. Simultaneously, the extraction steam of the corresponding high-pressure cylinder is cut off, the steam source of the feedwater pump turbine is switched to the steam supply of the steam header 12, the bypass steam is opened to the steam desuperheating device 13, and the reheater pressure is controlled not to exceed 1.1 times the rated value.

[0014] Preferably, it further includes: When the steam source pressure of the feedwater pump is detected to be lower than 0.8 times the rated value, the feedwater flow rate is lower than 70% of the rated value, or the condenser vacuum is lower than -85 kPa, a level three warning is triggered, and the emergency water supply pipeline from the hot water tank 16 to the boiler is automatically opened to ensure that the unit operates without interruption. When a single condenser failure is detected, all exhaust steam will be switched to the standby condenser within 30 seconds, and the unit load will be reduced to below 50% to maintain stable unit operation. When a fault is detected in a single high-pressure cylinder, the steam supply to the faulty high-pressure cylinder is immediately cut off, while the other high-pressure cylinder is kept running to maintain the minimum load requirement of the power grid and avoid power deficit in the power grid.

[0015] Compared with the prior art, the present invention has the following beneficial effects: On the one hand, the independent steam inlet design of the dual high-pressure cylinders enables multi-mode switching between single-cylinder operation, dual-cylinder parallel operation, and single-cylinder rotating standby, thereby improving load regulation rate, reducing stable combustion load, and meeting the grid's second-level response requirements. On the other hand, the steam header integrates the extraction and exhaust steam of each section, achieving cascaded utilization of heat: the exhaust steam from the high-pressure cylinder is used for heating feedwater, partially for driving the feedwater pump turbine, and partially for heating, thereby improving system thermal efficiency. Furthermore, the dual condensers are mutually redundant via interconnecting pipes, allowing for rapid exhaust steam switching in case of a single unit failure, preventing unit tripping; the hot water tank serves as an emergency water supply source, starting within 5 seconds in case of insufficient feedwater flow or feedwater pump failure, covering part or all of the rated feedwater flow, thus mitigating the risk of non-stoppage caused by feedwater problems in traditional units. Moreover, the system can simultaneously support multiple tasks such as power generation, heating, and peak shaving, with heating capacity covering industrial steam and domestic hot water needs. Even during unit maintenance or fault conditions, single-cylinder operation can still ensure the grid's basic load and heating needs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a peak-shaving and frequency regulation system coupled with multiple generating units, provided in an exemplary embodiment; Figure 2 This is a flowchart of a peak-shaving and frequency regulation method for coupling multiple generating units, provided in an exemplary embodiment.

[0017] The diagram is marked 0- Boiler, 0-1- Steam pipe to the first high-pressure cylinder, 0-2- Steam pipe to the second high-pressure cylinder; 1- First high-pressure cylinder, 1-1- Generator, 1-2- High-pressure cylinder exhaust, 1-3- Second stage extraction, 1-4- First steam pipe, 1-5- Pipe to reheater, 1-6- Pipe to steam header; 2- Second high-pressure cylinder, 2-1- High-pressure exhaust, 2-2- Second steam pipe, 2-3- Second stage extraction, 2-4- Reheater; 3- Intermediate-pressure cylinder, 3-1- Third stage extraction, 3-2- Fourth stage extraction, 3-3- Heating steam; 4- First high-pressure heater, 5- Second high-pressure heater, 6- Third high-pressure heater, 7- Deaerator 8-Feedwater pump turbine, 8-1-Feedwater pump turbine exhaust, 9-Feedwater pump, 9-1-Cooling water, 9-2-Feedwater; 10-First condenser, 10-1-Connecting pipe; 11-Second condenser, 11-1-Steam connecting pipe, 11-2-Condensate pipe; 12-Steam header, 12-1-Steam pipe to feedwater pump turbine, 12-2-Steam pipe to deaerator, 12-3-Fourth stage extraction steam to feedwater pump turbine pipe; 13-Steam desuperheating device, 13-1-High temperature steam pipe, 13-2-Bypass steam pipe; 14-Steam cooler, 15-Heat exchanger, 16-Hot water tank. Detailed Implementation

[0018] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with one or more embodiments of the present invention. Rather, they are merely examples of systems consistent with one or more embodiments of the present invention as detailed in the appended claims.

[0019] It should be noted that in other embodiments, the corresponding methods are not necessarily performed in the order shown and described in this invention. The method comprises steps. In some other embodiments, the method may include more or fewer steps than those described in this invention. Furthermore, a single step described in this invention may be broken down into multiple steps in other embodiments; and multiple steps described in this invention may be combined into a single step in other embodiments.

[0020] During peak periods when wind and solar power resources are abundant, coal-fired power units need to proactively reduce their output and make room for grid connection to ensure that clean electricity is fully connected to the grid and consumed. When extreme weather causes a sharp drop in the output of new energy sources, or when there is a power shortage during peak electricity load periods, coal-fired power units need to quickly start up and make up for the peak load through minute-level or even second-level response to promptly smooth out power fluctuations in the grid.

[0021] Currently, coal-carrying power units adopt a single high-pressure cylinder configuration. Under this configuration, the unit has problems such as low regulation rate and small adjustable load range during the load regulation phase. When the grid load fluctuates rapidly, the unit's own regulation performance cannot meet the grid's real-time response requirements.

[0022] To address the shortcomings of related technologies, this invention proposes a peak-shaving and frequency regulation system and method for coupling multiple generating units.

[0023] Figure 1 This is a schematic diagram of a peak-shaving and frequency regulation system coupled with multiple generating units, provided as an exemplary embodiment. Figure 1 As shown, this peak-shaving and frequency-modulating system consists of five main modules: High-pressure cylinder separate power generation system: The main steam generated by boiler 0 is divided into two paths, one sent to the first high-pressure cylinder 1 via pipe 0-1, and the other sent to the second high-pressure cylinder 2 via pipe 0-2. The exhaust steam 1-2 of the first high-pressure cylinder 1 is divided into three paths: one path is sent to the steam header 12 and the first condenser 10 via pipe 1-4; one path is sent to the first high-pressure heater 4 for heating feedwater; and one path is sent to the reheater 2-4 via pipe 1-5. The second-stage extraction steam 1-3 of the first high-pressure cylinder 1 is sent to the second high-pressure heater 5. The exhaust steam 2-1 of the second high-pressure cylinder 2 is divided into three paths: one path is sent to the first high-pressure heater 4; one path is sent to the second condenser 11 via pipe 2-2; and one path is sent to the steam header 12. The second-stage extraction steam 2-3 of the second high-pressure cylinder 2 is sent to the second high-pressure heater 5. The steam at the outlet of the reheater 2-4 is sent to the intermediate-pressure cylinder 3 to perform work.

[0024] High and medium pressure cylinder power generation system: The third-stage extraction steam 3-1 from the intermediate pressure cylinder 3 is sent to the third high-pressure heater 6, and the fourth-stage extraction steam 3-2 is divided into two paths: one path is sent to the deaerator 7 for heating, and the other path is sent to the feedwater pump turbine 8 via pipeline 12-3. Part of the exhaust steam from the intermediate pressure cylinder 3 is output as heating steam via pipeline 3-3.

[0025] Water system: Steam from steam header 12 is sent to feedwater pump turbine 8 via pipe 12-1 to drive feedwater pump 9. Feedwater is sent to high-pressure heaters 4, 5, and 6 via pipe 9-2 and then returned to boiler 0. Another outlet of feedwater pump 9 is sent to steam header 12 to reduce the steam temperature of header.

[0026] Vacuum System: The first condenser 10 and the second condenser 11 are connected by a steam connection pipe 11-1. The exhaust steam from the high-pressure cylinder and the exhaust steam from the feedwater pump turbine can be switched to either condenser via valves. The two condensers serve as backups for each other. The condensate from the second condenser 11 is sent to the deaerator 7 via pipe 11-2.

[0027] Heating System: The heating steam from the intermediate pressure cylinder 3 (3-3) merges with the heating steam from the steam header 12. One path bypasses through 13-2 and enters the steam desuperheating device 13 for desuperheating and pressure reduction, then supplies industrial steam externally through pipeline 13-1. The other path enters the steam cooler 14, using condensate from 11-2 as desuperheating water. After cooling, it enters the heat exchanger 15 to exchange heat with the condensate. The hot water after heat exchange and the condensate from the cooled steam are both sent to the hot water tank 16. The water in the hot water tank 16 is used for external heating on one side and sent to the boiler 0 via an emergency water supply pipeline on the other. In this embodiment, on the one hand, the independent steam inlet design of the dual high-pressure cylinders enables multi-mode switching between single-cylinder operation, dual-cylinder parallel operation, and single-cylinder rotating standby, thereby improving the load regulation rate, reducing the stable combustion load, and meeting the grid's second-level response requirements. On the other hand, the steam header integrates the extraction and exhaust steam of each section, achieving cascaded utilization of heat: the exhaust steam from the high-pressure cylinder is used to heat feedwater, partially to drive the feedwater pump turbine, and partially for heating, thereby improving the system's thermal efficiency. Furthermore, the dual condensers are mutually redundant via interconnecting pipes, allowing for rapid exhaust steam switching in case of a single unit failure, preventing unit tripping; the hot water tank serves as an emergency water supply source, initiating water replenishment within 5 seconds in case of insufficient feedwater flow or feedwater pump failure, covering part or all of the rated feedwater flow, thus mitigating the risk of non-stoppage caused by feedwater problems in traditional units. Moreover, the system can simultaneously support multiple tasks such as power generation, heating, and peak shaving, with heating capacity covering industrial steam and domestic hot water needs. Even during unit maintenance or fault conditions, single-cylinder operation can still ensure the grid's basic load and heating needs.

[0028] In one embodiment, the third-stage extraction steam 3-1 of the intermediate-pressure cylinder 3 is sent to the third high-pressure heater 6, the fourth-stage extraction steam 3-2 serves as the normal heating steam source for the deaerator 7, and the steam from the steam header 12 serves as the backup heating steam source for the deaerator 7; when the pressure of the fourth-stage extraction steam is lower than the set threshold, the steam supply is automatically switched to the steam header 12.

[0029] During normal operation, the deaerator 7 uses the four-stage extraction steam 3-2 of the intermediate pressure cylinder 3 as the main heating steam source; when the extraction steam pressure of 3-2 is lower than 0.8MPa, the 12-2 pipeline valve is automatically opened to switch to steam supply from the steam header 12, ensuring the heating effect of the deaerator and preventing the dissolved oxygen in the feedwater from exceeding the standard.

[0030] In one embodiment, the steam source of the feedwater pump turbine 8 has an automatic switching logic: during normal operation, the fourth-stage extraction steam 3-2 is used as the main steam source, and the steam from the steam header 12 is used as the backup steam source; when the pressure of the fourth-stage extraction steam is insufficient, the temperature is abnormal, or the feedwater pump turbine malfunctions, the steam source is switched to the steam header 12 within 10 seconds to ensure the continuous operation of the feedwater pump.

[0031] Specifically, when the extraction steam pressure of 3-2 is lower than 0.7MPa or the temperature is lower than 300℃, the control system opens valve 12-1 and closes valve 12-3 within 10 seconds to complete the steam source switching and ensure the continuous and stable operation of feedwater pump 9.

[0032] In one embodiment, the first condenser 10 and the second condenser 11 are connected on the steam side through a steam connection pipe 11-1. The exhaust steam from the high-pressure cylinder and the exhaust steam from the feedwater pump turbine can be freely switched to either condenser through valves. When the vacuum of a single condenser is lower than the set value or a malfunction occurs, all exhaust steam can be switched to another condenser within 30 seconds to avoid unit tripping.

[0033] Specifically, when the vacuum of any condenser is lower than -85 kPa, the control system will open the connecting pipe valve within 30 seconds to switch all exhaust steam to the standby condenser. A single condenser can handle 100% of the exhaust steam load, thus preventing the unit from tripping due to low vacuum.

[0034] In one embodiment, an emergency water supply pipeline is provided between the hot water tank 16 and the boiler 0, and a quick-closing regulating valve is installed on the pipeline. When the unit experiences a feedwater temperature lower than the set value (e.g., 70% of the rated value), insufficient feedwater flow (e.g., below 150°C), feedwater pump steam source failure, or condenser vacuum abnormality, the quick-closing regulating valve opens within 5 seconds, and the high-temperature water in the hot water tank 16 quickly supplies water to the boiler. The supply water flow can cover 30% to 100% of the boiler's rated feedwater, thereby solving the non-shutdown problem caused by insufficient feedwater in traditional units.

[0035] In one embodiment, the desuperheating water for the steam cooler 14 comes from the condensate pipe 11-2 of the second condenser 11. The flow rate of the desuperheating water is automatically adjusted according to the steam temperature at the outlet of the steam cooler to ensure that the steam temperature entering the heat exchanger 15 is ≤150℃. The condensate after heat exchange is sent to the hot water tank 16 and mixed with the condensate after steam cooling for storage. The water temperature in the hot water tank is maintained at 80~120℃, which not only ensures the heating quality but also avoids excessive temperature fluctuations when the boiler makes emergency water replenishment.

[0036] In one embodiment, the system is configured with three off-peak grid load operation modes: High and medium pressure unit maintenance mode: Only the first high-pressure cylinder 1 operates, and the 0-2 pipeline is closed. The exhaust steam 1-2 from the first high-pressure cylinder 1 enters the reheater 2-4 via the 1-5 pipeline, and then bypasses the steam desuperheating device 13 via the 13-2 pipeline for heating; part of the exhaust steam enters the steam header 12 via the 1-4 pipeline to drive the feedwater pump turbine 8 and the heating deaerator 7; part of the water output from the feedwater pump 9 is sent to the steam header 12 for cooling; the hot water tank 16 serves as an emergency boiler makeup water source. In this mode, the unit can maintain 20% Pe load operation to ensure heating demand.

[0037] Single-high-pressure cylinder unit maintenance mode: Only the second high-pressure cylinder 2 and the intermediate-pressure cylinder 3 operate, and the 0-1 pipeline is closed. The exhaust steam 2-1 from the second high-pressure cylinder 2 enters the reheater 2-4 and is then sent to the intermediate-pressure cylinder 3 to perform work. The bypass system is closed. When the load is ≥50%Pe, the extraction steam from sections 2-1, 2-3, 3-1, and 3-2 is activated. The steam source for the feedwater pump turbine 8 and deaerator 7 is switched to the fourth-stage extraction steam 3-2. The steam from the steam header 12 is mainly used for heating. In this mode, the unit can maintain operation at 50%~100% Pe load.

[0038] Dual-unit operation mode: The first high-pressure cylinder 1 and the second high-pressure cylinder 2 operate simultaneously. The exhaust steam from the two cylinders merges and enters the reheater 2-4. The reheated steam is then sent to the intermediate-pressure cylinder 3 to perform work. All extraction steam lines 1-2, 1-3, 2-1, 2-3, 3-1, and 3-2 are engaged. Steam from steam header 12 serves as both heating and backup steam source. When the steam pressure exceeds 1.1 times the rated value, some steam bypasses through 13-2 and enters the steam desuperheating device 13 for pressure relief. In this mode, the unit can maintain 100% Pe full-load operation.

[0039] In one embodiment, when the power grid dispatch command requires a load ramp rate ≥ 3%Pe / min, valves 0-1 and 0-2 are simultaneously opened, allowing steam to enter both the first high-pressure cylinder 1 and the second high-pressure cylinder 2. All extraction steam valves are fully opened, switching the steam source for the feedwater pump turbine 8 to the four-stage extraction steam 3-2. Simultaneously, the emergency water supply pipeline from the hot water tank 16 to the boiler 0 is opened, supplying water to the boiler at 50%~100% of the rated flow rate to increase the boiler's evaporation capacity. Under this mode, the load ramp rate can reach 5%~8%Pe / min, meeting the peak demand of the power grid.

[0040] When the power grid dispatch command requires a load reduction rate ≥ 3%Pe / min, a two-level load reduction logic is executed: First-level load reduction: Close the 0-1 pipeline valve, cut off the steam inlet of the first high-pressure cylinder 1 and enter the rotating standby state, send all of its exhaust steam 1-2 into the first condenser 10, cut off the extraction steam of 1-2 and 1-3, and the load adjustment rate can reach 3%~5%Pe / min; Secondary load reduction: Based on the primary load reduction, close the 0-2 pipeline valve, cut off the steam inlet of the second high-pressure cylinder 2, and send all of its exhaust steam 2-1 to the second condenser 11. Cut off the extraction steam of 2-1, 2-3, 3-1, and 3-2, switch the steam source of the feedwater pump turbine 8 to the steam header 12, and open the 13-2 bypass to control the reheater pressure. The load regulation rate can reach 5%~8%Pe / min.

[0041] In response to this embodiment, the present invention also proposes a peak-shaving and frequency-modulation method for coupling multiple generating units, such as... Figure 2 As shown, it includes: Step 201: When the power grid dispatching command requires the load increase rate to be ≥3%Pe / min, start the first high-pressure cylinder (1) and the second high-pressure cylinder 2 to simultaneously introduce steam, fully open the extraction steam valves of each section, switch the steam source of the feedwater pump turbine to four-stage extraction steam, and at the same time open the emergency water supply pipeline from the hot water tank 16 to the boiler to supply water to the boiler at 50%~100% of the rated flow rate, increase the boiler evaporation, and achieve rapid load ramp-up; Step 202: When the power grid dispatching instruction requires a load reduction rate of ≥3%Pe / min, close the main steam valve in the order of first cutting off the steam inlet of the first high-pressure cylinder and then cutting off the steam inlet of the second high-pressure cylinder, simultaneously cut off the extraction steam of the corresponding high-pressure cylinder, switch the steam source of the feedwater pump turbine to the steam header 12, open the bypass steam to the steam desuperheating device 13, and control the reheater pressure to not exceed 1.1 times the rated value.

[0042] In one embodiment, when a system failure occurs, the following safety control steps are performed: When the steam source pressure of the feedwater pump is detected to be lower than 0.8 times the rated value, the feedwater flow rate is lower than 70% of the rated value, or the condenser vacuum is lower than -85 kPa, a level three warning is triggered, and the emergency water supply pipeline from the hot water tank 16 to the boiler 0 is automatically opened. At the same time, the steam source of the feedwater pump turbine 8 is switched to the steam header 12 to ensure that the unit operates without interruption.

[0043] When a single condenser failure is detected, the 11-1 connecting pipe valve should be opened within 30 seconds to switch all exhaust steam to the standby condenser. At the same time, the unit load should be reduced to below 50% to maintain stable unit operation and avoid tripping.

[0044] When a single high-pressure cylinder failure is detected, immediately close the corresponding main steam pipeline valve, cut off the steam supply to the faulty high-pressure cylinder, and keep the other high-pressure cylinder running to maintain a minimum load of 20%~50% Pe to avoid power grid deficit.

[0045] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0046] The foregoing has described specific embodiments of the invention. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0047] The terminology used in one or more embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” used in one or more embodiments of the invention and in the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0048] It should be understood that although the terms first, second, third, etc., may be used to describe various information in one or more embodiments of the present invention, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of one or more embodiments of the present invention, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0049] The above description is merely a preferred embodiment of one or more embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of the present invention should be included within the protection scope of one or more embodiments of the present invention.

Claims

1. A peak-shaving and frequency-regulating system with multiple generator units coupled together, characterized in that, This includes a high-pressure cylinder separate power generation system, an intermediate and high-pressure cylinder power generation system, a water system, a vacuum system, and a heating system; The high-pressure cylinder separate power generation system includes a boiler (0), a first high-pressure cylinder (1), a second high-pressure cylinder (2), a generator (1-1), a reheater (2-4), and a steam header (12); the main steam generated by the boiler (0) is divided into two paths, which are sent to the first high-pressure cylinder (1) through the first high-pressure cylinder steam pipe (0-1) and to the second high-pressure cylinder (2) through the second high-pressure cylinder steam pipe (0-2). The high-pressure cylinder exhaust of the first high-pressure cylinder (1) is divided into three paths: one path is sent to the steam header (12) and the first condenser (10) through the first steam pipeline (1-4), one path is sent to the first high-pressure heater (4), and one path is sent to the reheater (2-4); the second stage extraction steam (1-3) of the first high-pressure cylinder (1) is sent to the second high-pressure heater (5); The high-pressure cylinder exhaust of the second high-pressure cylinder (2) is divided into three paths: one path is sent to the first high-pressure heater (4), one path is sent to the second condenser (11), and one path is sent to the steam header (12); the second stage extraction steam (2-3) of the second high-pressure cylinder (2) is sent to the second high-pressure heater (5); the steam at the outlet of the reheater (2-4) is sent to the intermediate-pressure cylinder (3); The water system includes a first high-pressure heater (4), a second high-pressure heater (5), a third high-pressure heater (6), a deaerator (7), a feedwater pump turbine (8), and a feedwater pump (9); part of the steam from the steam header (12) is sent to the feedwater pump turbine (8) to drive the feedwater pump (9), and part of the fourth-stage extraction steam is also sent to the feedwater pump turbine (8); the steam from the steam header (12) is also sent to the deaerator (7) to heat the feedwater; the feedwater from the outlet of the feedwater pump (9) is divided into two paths: one path returns to the boiler (0) through the high-pressure heater system, and the other path is sent to the steam header (12) to regulate the steam temperature; The vacuum system includes a first condenser (10), a second condenser (11), and a steam connecting pipe (11-1) connecting the two. The exhaust steam from the feedwater pump turbine (8-1) and the exhaust steam from the high-pressure cylinder can be selectively sent to the first condenser (10) or the second condenser (11), with the two condensers serving as backups for each other. The condensate from the second condenser (11) is sent to the deaerator (7) via the condensate pipe (11-2). The heating system includes a steam desuperheating device (13), a steam cooler (14), a heat exchanger (15), and a hot water tank (16). The four-stage extraction steam (3-3) of the intermediate pressure cylinder (3) is combined with the heating steam of the steam header (12). One path is desuperheated and depressurized by the steam desuperheating device (13) and then supplied to the outside as high-temperature steam. The other path is cooled by the steam cooler (14) and then sent to the heat exchanger (15) to exchange heat with the condensate. The hot water after heat exchange and the condensate after steam cooling are both sent to the hot water tank (16). The water in the hot water tank (16) is supplied to the outside as heating and is sent to the boiler (0) as emergency replenishment water.

2. The peak-shaving and frequency regulation system with multiple generator sets coupled according to claim 1, characterized in that, The three-stage extraction steam (3-1) of the intermediate pressure cylinder (3) is sent to the third high-pressure heater (6), the four-stage extraction steam (3-2) serves as the normal heating steam source for the deaerator (7), and the steam from the steam header (12) serves as the backup heating steam source for the deaerator (7); when the pressure of the four-stage extraction steam is lower than the set threshold, it automatically switches to the steam header (12) for steam supply.

3. The peak-shaving and frequency regulation system with multiple generator sets coupled according to claim 1, characterized in that, The steam source of the feedwater pump turbine (8) has an automatic switching logic: during normal operation, the four-stage extraction steam (3-2) is used as the main steam source, and the steam from the steam header (12) is used as the backup steam source; when the pressure of the four-stage extraction steam is insufficient, the temperature is abnormal, or the feedwater pump turbine fails, the steam source is switched to the steam header (12) within 10 seconds to ensure the continuous operation of the feedwater pump.

4. The peak-shaving and frequency-regulating system with multiple generator sets coupled according to claim 1, characterized in that, The first condenser (10) and the second condenser (11) are connected on the steam side through a steam connecting pipe (11-1). The exhaust steam from the high-pressure cylinder and the exhaust steam from the feedwater pump turbine can be freely switched to any condenser through valves. When the vacuum of a single condenser is lower than the set value or a fault occurs, all exhaust steam can be switched to another condenser within 30 seconds to avoid the unit tripping.

5. A peak-shaving and frequency-regulating system with multiple generator sets coupled according to claim 1, characterized in that, An emergency water supply pipeline is provided between the hot water tank (16) and the boiler (0), and a quick-closing regulating valve is installed on the pipeline. When the unit experiences a water supply temperature lower than the set value, insufficient water supply flow, a water supply pump steam source failure, or an abnormal condenser vacuum, the quick-closing regulating valve will open within 5 seconds, and the high-temperature water in the hot water tank (16) will quickly supply water to the boiler. The water supply flow can cover 30% to 100% of the boiler's rated water supply.

6. A peak-shaving and frequency-regulating system with multiple generator sets coupled according to claim 1, characterized in that, The desuperheating water of the steam cooler (14) comes from the condensate pipe (11-2) of the second condenser (11). The flow rate of the desuperheating water is automatically adjusted according to the steam outlet temperature of the steam cooler. The condensate after heat exchange is sent to the hot water tank (16) and mixed with the condensate after steam cooling for storage. The water temperature of the hot water tank is maintained at 80~120℃.

7. A peak-shaving and frequency-regulating system with multiple coupled generating units according to claim 1, characterized in that, The system is configured with three operating modes for low grid load conditions: High and medium pressure unit maintenance mode: only the first high pressure cylinder (1) is running. Its exhaust steam enters the steam desuperheating device (13) for heating through the reheater bypass. Part of the exhaust steam is sent to the steam header (12) for heating the deaerator and driving the feedwater pump turbine. Part of the water output from the feedwater pump (9) is sent to the steam header (12) for cooling. The hot water tank (16) serves as an emergency water source for the boiler. Maintenance mode of single high pressure cylinder unit: only the high and medium pressure unit consisting of the second high pressure cylinder (2) and the intermediate pressure cylinder (3) is in operation. The exhaust steam of the second high pressure cylinder enters the reheater (2-4) and is then sent to the intermediate pressure cylinder (3) to do work. When the load is ≥50%, the extraction steam of each section is put into operation. The steam source of the feedwater pump turbine and deaerator is switched to the four-stage extraction steam. The steam of the steam header (12) is mainly used for heating. Dual-unit operation mode: The first high-pressure cylinder (1) and the second high-pressure cylinder (2) operate simultaneously. After the exhaust steam from the two cylinders merges, it enters the reheater (2-4) and is sent to the intermediate-pressure cylinder (3) to do work. Steam extraction is put into operation throughout the section. Steam from the steam header (12) is used as a heating and backup steam source. Overpressure steam enters the steam desuperheating device (13) through the bypass to depressurize.

8. A peak-shaving and frequency-regulating system with multiple generator sets coupled according to claim 7, characterized in that, The rapid adjustment logic under sudden load drop conditions in the power grid is as follows: First-level load reduction: Cut off the steam inlet of the first high-pressure cylinder steam pipe (0-1), the first high-pressure cylinder (1) enters the rotating standby state, and all its exhaust steam is sent to the condenser. Cut off the relevant extraction steam of the first high-pressure cylinder. The load adjustment rate can reach 3%~5%Pe / min. Secondary load reduction: Based on the first-level load reduction, the steam inlet of the second high-pressure cylinder steam pipeline (0-2) is cut off, the second high-pressure cylinder (2) is shut down, and all its exhaust steam is sent to the condenser. All extraction steam from the second high-pressure cylinder and the intermediate-pressure cylinder is cut off, and the steam source of the feedwater pump turbine is switched to the steam header (12) for steam supply. The load regulation rate can reach 5%~8%Pe / min.

9. A method for peak shaving and frequency regulation of multiple coupled generating units, based on the system described in any one of claims 1-8, characterized in that, include: When the power grid dispatching command requires the load increase rate to be ≥3%Pe / min, the first high-pressure cylinder (1) and the second high-pressure cylinder (2) are started to simultaneously introduce steam, and all extraction steam valves are fully opened to switch the steam source of the feedwater pump turbine to four-stage extraction steam. At the same time, the emergency water supply pipeline from the hot water tank (16) to the boiler is opened to supply water to the boiler at 50%~100% of the rated flow rate, thereby increasing the boiler evaporation rate and achieving rapid load ramp-up. When the power grid dispatching command requires a load reduction rate of ≥3%Pe / min, the main steam valve is closed in the order of first cutting off the steam inlet of the first high-pressure cylinder and then cutting off the steam inlet of the second high-pressure cylinder. Simultaneously, the extraction steam of the corresponding high-pressure cylinder is cut off, the steam source of the feedwater pump turbine is switched to the steam header (12) for steam supply, the bypass steam is opened to the steam desuperheating device (13), and the reheater pressure is controlled to not exceed 1.1 times the rated value.

10. A method for peak shaving and frequency modulation of multiple coupled generating units according to claim 9, characterized in that, Also includes: When the steam source pressure of the feedwater pump is detected to be lower than 0.8 times the rated value, the feedwater flow rate is lower than 70% of the rated value, or the condenser vacuum is lower than -85kPa, a level three warning is triggered, and the emergency water supply pipeline from the hot water tank (16) to the boiler is automatically opened, and the steam source of the feedwater pump turbine is switched to the steam header (12). When a single condenser failure is detected, all exhaust steam will be switched to the standby condenser within 30 seconds, and the unit load will be reduced to below 50% to maintain stable unit operation. When a fault is detected in a single high-pressure cylinder, the steam supply to the faulty high-pressure cylinder is immediately cut off, while the other high-pressure cylinder is kept running to maintain the minimum load requirement of the power grid and avoid power deficit in the power grid.

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