Method and system for improving frequency modulation capability of coal-fired power generation unit

Abstract

The invention discloses a method and system for improving the frequency modulation capacity of a coal-fired power generation unit, and belongs to the technical field of coal-fired power generation. According to the method for improving the frequency modulation capability of the coal-fired power generator set, the operation frequency of the coal-fired power generator set is monitored and is compared with the power grid frequency in real time, whether the output power of the coal-fired power generator set needs to be adjusted to meet the power grid requirement or not can be rapidly judged, and the frequency modulation capability is improved by combining setting of frequency modulation reference parameters. The adjustment amplitude can be accurately controlled, so that the response speed and precision of frequency modulation are improved, and stable operation of a power grid is facilitated; according to the difference value of the operation frequency of the coal-fired power generation unit and the power grid frequency and the comparison result of the frequency modulation reference parameters, a regulation and control strategy is accurately determined, the exhaust flow is flexibly selected to be independently adjusted or the exhaust flow and the main steam flow are cooperatively adjusted, and therefore the optimal regulation and control effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired power generation, and particularly to a method and system for improving the frequency regulation ability of coal-fired power generation units. Background Art

[0002] With the clear proposal of the goals of carbon peak and carbon neutrality, the installed capacity of renewable energy sources such as solar energy and wind energy is increasing at an unprecedented speed. However, new energy power generation methods such as wind energy and solar energy are easily affected by environmental factors and exhibit significant time-varying characteristics, which undoubtedly bring new challenges to the safe and stable operation of the power grid. As the main power source in China at present, coal-fired power generation needs to shoulder more responsibilities for peak shaving and frequency regulation to ensure the stable operation of the power grid.

[0003] Improving the frequency regulation ability of coal-fired power generation units is crucial for effectively accommodating and integrating more new energy power. New energy power generation has natural volatility, that is, both the social electricity demand and the new energy power generation are constantly changing, and a dynamic balance must be maintained between the two at all times; when there is a difference between the new energy power generation and the social electricity demand, the coal-fired units need to be flexibly adjusted to make up for this gap. When the frequency regulation and peak shaving capabilities of coal-fired units are improved, more new energy power generation can be accommodated and connected to the power grid, thus promoting the further development of new energy power generation. Although existing coal-fired power generation units have a certain frequency regulation ability, when facing the high volatility and rapid changes of new energy power generation, there are still problems such as slow response speed, insufficient regulation accuracy, and lack of flexibility. These problems limit the power grid's ability to accommodate new energy power and affect the further development of new energy power generation.

[0004] Therefore, how to provide a method for improving the frequency regulation ability of coal-fired power generation units to better adapt to the volatility of new energy power generation and ensure the safe and stable operation of the power grid has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and system for improving the frequency regulation ability of coal-fired power generation units to overcome the problem of insufficient frequency regulation ability of coal-fired power generation units in the prior art.

[0006] The present invention solves the above technical problems through the following technical solutions: A method for improving the frequency regulation ability of a coal-fired power generation unit, the coal-fired power generation unit includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder connected in sequence; the method for improving the frequency regulation ability of the coal-fired power generation unit specifically includes the following steps: S1. Set frequency regulation reference parameters based on the operating ability of the coal-fired power generation unit; S2. Obtain the operating frequency of the coal-fired power generation unit, and determine whether the operating frequency is greater than the grid frequency. If the determination is yes, then execute step S3; if the determination is no, then execute step S4; S3. Calculate the difference between the operating frequency and the grid frequency, and determine whether the difference is less than the frequency modulation reference parameter. If the determination is yes, then increase the exhaust gas flow rate from the high-pressure cylinder into the intermediate-pressure cylinder, so that under the condition that the work capacity of the high-pressure cylinder remains unchanged, reduce the work capacity of the intermediate-pressure cylinder and the low-pressure cylinder; if the determination is no, then increase the flow rate of the exhaust gas from the high-pressure cylinder into the intermediate-pressure cylinder, and reduce the main steam flow rate into the high-pressure cylinder, so as to reduce the work capacity of the high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder, thereby realizing the reduction of the operating frequency of the coal-fired power generation unit; S4. Calculate the difference between the grid frequency and the operating frequency, and determine whether the difference is less than the frequency modulation reference parameter. If the determination is yes, then reduce the exhaust gas flow rate from the high-pressure cylinder into the intermediate-pressure cylinder, so that under the condition that the work capacity of the high-pressure cylinder remains unchanged, enhance the work capacity of the intermediate-pressure cylinder and the low-pressure cylinder; if the determination is no, then reduce the flow rate of the exhaust gas from the high-pressure cylinder into the intermediate-pressure cylinder, and increase the main steam flow rate into the high-pressure cylinder, so as to enhance the work capacity of the high-pressure cylinder, the intermediate-pressure cylinder and the low-pressure cylinder, and realize the increase of the operating frequency of the coal-fired power generation unit.

[0007] A further improvement of the present invention lies in that: the range of the frequency modulation reference parameter is 0.08~0.12 Hz.

[0008] A further improvement of the present invention lies in that: the grid frequency is 50 Hz stipulated by the state.

[0009] A further improvement of the present invention lies in that: when adjusting the operating frequency of the coal-fired power generation unit, the inlet temperature of the intermediate-pressure cylinder shall not be higher than 632 °C.

[0010] The present invention also provides a system for improving the frequency modulation ability of a coal-fired power generation unit, which can implement the method for improving the frequency modulation ability of a coal-fired power generation unit as described above. The system further includes: main steam and reheated steam generated by the boiler, a main steam valve and an intermediate-pressure cylinder cooling pipeline valve; The outlet of the reheated steam is connected to the inlet of the intermediate-pressure cylinder; The outlet of the main steam is connected to the inlet of the high-pressure cylinder through the main steam valve. The exhaust outlet of the high-pressure cylinder is divided into two paths. One path is connected to the inlet of the intermediate-pressure cylinder through the intermediate-pressure cylinder cooling pipeline valve, and the other path is connected to the inlet of the reheated steam through the inlet of the boiler.

[0011] A further improvement of the present invention lies in that: the system further includes a high-pressure heater. The extraction outlet of the high-pressure cylinder is connected to the denitration system of the coal-fired power generation unit through the high-pressure heater; when adjusting the operating frequency of the coal-fired power generation unit, the inlet flue gas temperature range of the denitration system is 300~400 °C.

[0012] A further improvement of the present invention lies in that: the system further includes a deaerator, and the extraction outlet of the intermediate pressure cylinder is connected to the high-pressure heater through the deaerator; when adjusting the operating frequency of the coal-fired power generation unit, the pressure range of the deaerator is 0.5 - 1.0 MPa.

[0013] A further improvement of the present invention lies in that: when adjusting the operating frequency of the coal-fired power generation unit, the operating frequency of the coal-fired power generation unit is controlled by adjusting the opening degrees of the main steam valve and the intermediate pressure cylinder cooling pipeline valve.

[0014] A further improvement of the present invention lies in that: when increasing the opening degree of the intermediate pressure cylinder cooling pipeline valve, the exhaust gas flow rate flowing from the high-pressure cylinder into the intermediate pressure cylinder increases; when decreasing the opening degree of the intermediate pressure cylinder cooling pipeline valve, the exhaust gas flow rate flowing from the high-pressure cylinder into the intermediate pressure cylinder decreases.

[0015] A further improvement of the present invention lies in that: when increasing the opening degree of the main steam valve, the main steam flow rate flowing into the high-pressure cylinder increases; when decreasing the opening degree of the main steam valve, the main steam flow rate flowing into the high-pressure cylinder decreases.

[0016] Compared with the prior art, the positive and progressive effects of the present invention are as follows: The method for improving the frequency modulation ability of a coal-fired power generation unit provided by the present invention can quickly determine whether the coal-fired power generation unit needs to adjust its output power to match the grid demand by monitoring the operating frequency of the coal-fired power generation unit and comparing it with the grid frequency in real time. Combining with the setting of frequency modulation reference parameters, the adjustment amplitude can be accurately controlled, thereby improving the response speed and accuracy of frequency modulation, and contributing to the stable operation of the power grid; according to the difference between the operating frequency of the coal-fired power generation unit and the grid frequency and the comparison result of the frequency modulation reference parameters, the control strategy is accurately determined, and the exhaust gas flow rate is flexibly selected for individual adjustment or the exhaust gas flow rate and the main steam flow rate are coordinately adjusted, so as to achieve the optimal control effect. Specifically: through different control strategies, the work capacities of the high-pressure cylinder, intermediate pressure cylinder and low-pressure cylinder are adjusted, so as to accurately control the operating frequency of the coal-fired power generation unit, make it closer to the grid frequency, and enhance the frequency modulation accuracy and the stability of the unit operation.

[0017] Furthermore, by setting reasonable frequency modulation reference parameters, the coal-fired power generation unit can more accurately match the grid demand, reduce frequency fluctuations, and thus enhance the stability and reliability of the power grid.

[0018] Furthermore, by strictly controlling the steam temperature at the inlet of the intermediate pressure cylinder, equipment wear and aging caused by overheating can be reduced, thereby extending the service life of the entire unit.

[0019] The system for improving the frequency regulation ability of a coal-fired power generation unit provided by the present invention is provided with a medium-pressure cylinder cooling pipeline valve and a main steam valve. Through coordinated adjustment, the accurate adjustment of the frequency of the coal-fired power generation unit is realized, which not only improves the response speed of frequency regulation, but also ensures the stability and accuracy during the frequency regulation process, thereby effectively improving the overall operation efficiency of the unit.

[0020] Further, by optimizing the operating conditions of the denitration system, not only the denitration efficiency is improved, but also the safe and efficient operation of the denitration system is ensured.

[0021] Further, by controlling the pressure of the deaerator within a reasonable range of 0.5 - 1.0 MPa, the efficient and stable operation of the deaerator is ensured, avoiding equipment damage, efficiency decline and safety hazards caused by too high pressure, and also preventing problems such as poor deaeration effect and unstable operation caused by too low pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The schematic diagrams in the specification are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation to the present invention.

[0023] Figure 1 It is a schematic flow diagram of a method for improving the frequency regulation ability of a coal-fired power generation unit of the present invention; Figure 2 It is a schematic connection diagram of a system for improving the frequency regulation ability of a coal-fired power generation unit of the present invention; Figure 3 It is a frequency regulation schematic diagram of the second embodiment of the present invention; Wherein, 1 is a high-pressure cylinder; 2 is a medium-pressure cylinder; 3 is a low-pressure cylinder; 4 is a boiler; 5 is a main steam valve; 6 is a medium-pressure cylinder cooling pipeline valve; 7 is main steam; 8 is reheated steam. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following further detailed description of the present invention is made in conjunction with the drawings and specific embodiments, which is an explanation of the present invention rather than a limitation.

[0025] See Figure 1 , a method for improving the frequency regulation ability of a coal-fired power generation unit, the coal-fired power generation unit includes a high-pressure cylinder 1, a medium-pressure cylinder 2 and a low-pressure cylinder 3 connected in sequence; the method for improving the frequency regulation ability of the coal-fired power generation unit specifically includes the following steps: S1. Set the frequency regulation reference parameters based on the operating ability of the coal-fired power generation unit; S2. Obtain the operating frequency of the coal-fired power generation unit, and judge whether the operating frequency is greater than the grid frequency. If the judgment is yes, execute step S3; if the judgment is no, execute step S4; S3. Calculate the difference between the operating frequency and the grid frequency, and determine whether the difference is less than the frequency modulation reference parameter. If the determination is yes, increase the exhaust gas flow rate from the high-pressure cylinder 1 into the intermediate-pressure cylinder 2, so that under the condition of unchanged work capacity of the high-pressure cylinder 1, reduce the work capacities of the intermediate-pressure cylinder 2 and the low-pressure cylinder 3; if the determination is no, increase the flow rate of the exhaust gas from the high-pressure cylinder 1 into the intermediate-pressure cylinder 2, and reduce the main steam flow rate into the high-pressure cylinder 1, so as to reduce the work capacities of the high-pressure cylinder 1, the intermediate-pressure cylinder 2, and the low-pressure cylinder 3, thereby reducing the operating frequency of the coal-fired power generating unit. S4. Calculate the difference between the grid frequency and the operating frequency, and determine whether the difference is less than the frequency modulation reference parameter. If the determination is yes, reduce the exhaust gas flow rate from the high-pressure cylinder 1 into the intermediate-pressure cylinder 2, so that under the condition of unchanged work capacity of the high-pressure cylinder 1, enhance the work capacities of the intermediate-pressure cylinder 2 and the low-pressure cylinder 3; if the determination is no, reduce the flow rate of the exhaust gas from the high-pressure cylinder 1 into the intermediate-pressure cylinder 2, and increase the main steam flow rate into the high-pressure cylinder 1, so as to enhance the work capacities of the high-pressure cylinder 1, the intermediate-pressure cylinder 2, and the low-pressure cylinder 3, and increase the operating frequency of the coal-fired power generating unit.

[0026] The method for improving the frequency modulation ability of a coal-fired power generating unit provided by the present invention can quickly determine whether the coal-fired power generating unit needs to adjust its output power to match the grid demand by monitoring the operating frequency of the coal-fired power generating unit and comparing it with the grid frequency in real time. Combined with the setting of the frequency modulation reference parameter, the adjustment amplitude can be accurately controlled, thereby improving the response speed and accuracy of frequency modulation and contributing to the stable operation of the power grid; according to the comparison result of the difference between the operating frequency and the grid frequency of the coal-fired power generating unit and the frequency modulation reference parameter, the control strategy is accurately determined, and the exhaust gas flow rate is flexibly selected for single adjustment or the exhaust gas flow rate and the main steam flow rate are coordinately adjusted, so as to achieve the optimal control effect. Specifically: through different control strategies, the work capacities of the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder are adjusted, thereby realizing the precise control of the operating frequency of the coal-fired power generating unit, making it closer to the grid frequency, enhancing the frequency modulation accuracy and the stability of the unit operation.

[0027] Specifically, the range of the frequency modulation reference parameter is 0.08 - 0.12 Hz; by setting a reasonable frequency modulation reference parameter, the coal-fired power generating unit can more accurately match the grid demand, reduce frequency fluctuations, and thus enhance the stability and reliability of the power grid.

[0028] Specifically, the grid frequency is 50Hz as stipulated by the state; according to the state regulations, the set value of the frequency is 50Hz, that is, the set value of the frequency must always be maintained at 50Hz during actual operation. Adjusting the frequency of the unit means adjusting the power of the unit. The operating frequency of the unit can be displayed in real time during the actual operation of the coal-fired unit, that is, the frequency is calculated based on the operating frequency. Therefore, frequency modulation means that when the work required by the outside world is the same as the work done by the unit, the operating frequency is 50Hz. When the power required by the outside world is greater than the work done by the unit, the operating frequency will be lower than 50Hz. At this time, it is necessary to increase the operating frequency by adjusting the flow rate to keep the frequency at 50Hz, and vice versa.

[0029] Specifically, when adjusting the operating frequency of the coal-fired power generation unit, the inlet temperature of the intermediate pressure cylinder 2 shall not be higher than 632°C; when the inlet temperature is too high, it is not conducive to the safe operation of the unit. By restricting the inlet temperature, the stability of the intermediate pressure cylinder of the steam turbine can be ensured.

[0030] See Figure 2 , based on the same inventive concept, the present invention also provides a system for improving the frequency modulation ability of a coal-fired power generation unit, which can implement the method for improving the frequency modulation ability of a coal-fired power generation unit as described above. The system further includes: main steam 7 and reheated steam 8 generated by the boiler 4, a main steam valve 5, and an intermediate pressure cylinder cooling pipeline valve 6; The outlet of the reheated steam 8 is connected to the inlet of the intermediate pressure cylinder 2; The outlet of the main steam 7 is connected to the inlet of the high-pressure cylinder 1 through the main steam valve 5. The exhaust outlet of the high-pressure cylinder 1 is divided into two paths. One path is connected to the inlet of the intermediate pressure cylinder 2 through the intermediate pressure cylinder cooling pipeline valve 6, and the other path is connected to the inlet of the reheated steam 8 through the inlet of the boiler 4.

[0031] The system for improving the frequency modulation ability of a coal-fired power generation unit provided by the present invention is provided with an intermediate pressure cylinder cooling pipeline valve and a main steam valve. The adjustment of the two valves can have a superimposed effect to increase the frequency modulation ability; through coordinated adjustment, the accurate adjustment of the frequency of the coal-fired power generation unit is realized, which not only improves the response speed of frequency modulation, but also ensures the stability and accuracy during the frequency modulation process, thereby effectively improving the overall operating efficiency of the unit.

[0032] Specifically, the system further includes a high-pressure heater. The extraction outlet of the high-pressure cylinder 1 is connected to the denitration system of the coal-fired power generation unit through the high-pressure heater; when adjusting the operating frequency of the coal-fired power generation unit, the inlet flue gas temperature range of the denitration system is 300 - 400°C; it is used to ensure the safe and efficient operation of the denitration system.

[0033] Specifically, the system further includes a deaerator. The extraction outlet of the intermediate pressure cylinder 2 is connected to the high-pressure heater through the deaerator. When adjusting the operating frequency of the coal-fired power generation unit, the pressure range of the deaerator is 0.5 - 1.0 MPa. When the pressure of the deaerator is too high, it will cause equipment damage, reduced efficiency, and potential safety hazards. When the pressure of the deaerator is too low, the deaeration effect is poor and the operation is unstable.

[0034] Specifically, when adjusting the operating frequency of the coal-fired power generation unit, the operating frequency of the coal-fired power generation unit is controlled by adjusting the opening degrees of the main steam valve 5 and the intermediate pressure cylinder cooling pipeline valve 6.

[0035] Specifically, when increasing the opening degree of the intermediate pressure cylinder cooling pipeline valve 6, the exhaust gas flow from the high-pressure cylinder 1 into the intermediate pressure cylinder 2 increases; when decreasing the opening degree of the intermediate pressure cylinder cooling pipeline valve 6, the exhaust gas flow from the high-pressure cylinder 1 into the intermediate pressure cylinder 2 decreases. When the opening degree of the intermediate pressure cylinder cooling pipeline valve 6 is increased, a part of the exhaust steam (low-temperature steam) of the high-pressure cylinder directly flows into the intermediate pressure cylinder, resulting in a decrease in the exhaust gas entering the boiler, that is, a decrease in the flow rate (high-temperature steam) at the outlet of the boiler after heating. Therefore, the steam temperature entering the intermediate pressure cylinder decreases, reducing the work capacity of the intermediate pressure cylinder. At the same time, the work capacity of the low-pressure cylinder decreases, while the work capacity of the high-pressure cylinder remains unchanged.

[0036] Specifically, when increasing the opening degree of the main steam valve 5, the main steam flow rate into the high-pressure cylinder 1 increases; when decreasing the opening degree of the main steam valve 5, the main steam flow rate into the high-pressure cylinder 1 decreases.

[0037] When the opening degree of the main steam valve 5 is increased, the flow rate into the high-pressure cylinder 1 increases, increasing the work capacity of the high-pressure cylinder. Subsequently, the flow rates into the intermediate pressure cylinder 2 and the low-pressure cylinder 3 also increase, increasing the work capacities of the intermediate pressure cylinder and the low-pressure cylinder, and increasing the operating frequency of the unit.

[0038] Embodiment 1 A system for improving the frequency modulation ability of a coal-fired power generation unit includes a medium-pressure cylinder cooling pipeline valve 6 and a main steam valve in the coal-fired power generation unit to cooperate and assist the unit in frequency modulation to improve the frequency modulation ability of the coal-fired power generation unit. The main steam 7 generated by the boiler 4 of the coal-fired unit enters the high-pressure cylinder 1 of the steam turbine to do work through the main steam valve 5. The exhaust steam of the high-pressure cylinder 1 flows into the boiler 4 for heating. The cooling flow of the medium-pressure cylinder 2 flows into the medium-pressure cylinder 2 of the steam turbine through the medium-pressure cylinder cooling pipeline valve 6. The extraction steam of the high-pressure cylinder 1 of the steam turbine heats the first high-pressure heater and the second high-pressure heater respectively. As a result, the reheated steam 8 of the heater of the boiler 4 flows into the medium-pressure cylinder 2 of the steam turbine. After the reheated steam 8 does work in the medium-pressure cylinder 2 of the steam turbine, it flows into the low-pressure cylinder 3 of the steam turbine. The extraction steam of the medium-pressure cylinder 2 of the steam turbine heats the third high-pressure heater, the deaerator and the fifth high-pressure heater respectively. The extraction steam of the medium-pressure cylinder 2 of the steam turbine heats the sixth high-pressure heater, the seventh high-pressure heater and the eighth high-pressure heater respectively. The high-pressure cylinder 1, the medium-pressure cylinder 2 and the low-pressure cylinder 3 of the steam turbine do work to generate electric energy by the generator. The exhaust steam of the low-pressure cylinder 3 of the steam turbine flows into the condensate deaerator water tank after being cooled by the air cooling island. The condensate water in the condensate deaerator water tank flows through the eighth high-pressure heater, the seventh high-pressure heater, the sixth high-pressure heater and the fifth high-pressure heater in sequence and then flows into the deaerator. The feed water in the deaerator flows through the third high-pressure heater, the second high-pressure heater and the first high-pressure heater in sequence, and the heated feed water flows into the boiler 4 for heating.

[0039] By adjusting the medium-pressure cylinder cooling pipeline valve 6, the flow rate of the cooling pipeline of the medium-pressure cylinder 2 can be adjusted. Adjusting 6 can control the flow rates into 7 and 11. When the flow rates into 7 and 11 change, naturally the work done by 7 and 11 also changes. By changing the work done by the high-pressure cylinder 1 and the medium-pressure cylinder 2 of the steam turbine of the coal-fired unit, the power of the generator of the coal-fired unit is adjusted, so as to maintain the frequency of the coal-fired unit at the grid frequency of 50 Hz.

[0040] At the same time, adjusting the main steam valve 5 and the medium-pressure cylinder cooling pipeline valve 6 can quickly change the work capacity of the high-pressure cylinder 1, the medium-pressure cylinder 2 and the low-pressure cylinder 3 of the steam turbine, so that the power of the generator can be quickly adjusted to meet the requirements of unit frequency modulation.

[0041] Embodiment 2 See Figure 3 , a method for improving the frequency modulation ability of a coal-fired power generation unit. The coal-fired power generation unit includes a high-pressure cylinder 1, a medium-pressure cylinder 2 and a low-pressure cylinder 3 connected in sequence; the method for improving the frequency modulation ability of the coal-fired power generation unit specifically includes the following steps: S1. Based on the operating capacity of the coal-fired power generation unit, set a frequency modulation reference parameter of 0.1 Hz; S2. Obtain the operating frequency of the coal-fired power generation unit as 50.043 Hz, and judge whether the operating frequency is greater than the grid frequency of 50 Hz. If the judgment is yes, then execute step S3; S3. Calculate that the difference between the operating frequency and the grid frequency is 0.043 Hz. Determine whether the difference is less than the frequency modulation reference parameter of 0.1 Hz. If the determination is yes, increase the exhaust gas flow from the high-pressure cylinder 1 into the intermediate-pressure cylinder 2, so that without changing the work capacity of the high-pressure cylinder 1, reduce the work capacities of the intermediate-pressure cylinder 2 and the low-pressure cylinder 3, and achieve reducing the operating frequency of the coal-fired generating unit.

[0042] Finally, it should be noted that: The above-listed embodiments exist only as one or more specific manifestation forms of the technical solution of the present invention. Their purpose is to clearly elaborate the concept, principle, and application method of the present invention through specific examples, rather than intending to limit the protection scope of the present invention to these specific embodiments. In fact, the true value of the present invention lies in the proposed technical idea and innovation point, rather than its manifestation form or implementation means.

[0043] For those of ordinary skill in the art, after deeply reading and understanding the technical solution of the present invention, they are fully capable of making various forms of changes, modifications, or equivalent replacements to the specific implementation manner of the invention based on their own professional knowledge and skills. These changes may include, but are not limited to: adjusting the value range of technical parameters, optimizing the algorithm flow to improve efficiency, replacing some technical components to achieve better compatibility or reduce costs, etc. As long as the changed technical solution still substantially maintains the technical features required to be protected by the original invention, that is, it can still achieve the core functions and effects of the present invention, then these changes should be regarded as falling within the protection scope of the pending claims of the present invention.

[0044] In addition, with the continuous progress and development of technology, new technical means and methods are emerging continuously, which also provides a broad space for the further improvement and perfection of the present invention. Therefore, the protection scope of the present invention should also include those reasonable and foreseeably improved and extended based on the existing technology. As long as these improvements and extensions do not depart from the basic principle and core concept of the present invention, they should be regarded as equivalents of the present invention and are also protected by the patent right.

Claims

1. A method for improving the frequency regulation ability of a coal-fired power generation unit, characterized in that, A coal-fired power generation unit includes a high-pressure cylinder (1), an intermediate-pressure cylinder (2), and a low-pressure cylinder (3) connected in sequence; the method for improving the frequency regulation ability of the coal-fired power generation unit specifically includes the following steps: S1. Set frequency regulation reference parameters based on the operating ability of the coal-fired power generation unit; S2. Obtain the operating frequency of the coal-fired power generation unit, and determine whether the operating frequency is greater than the grid frequency. If the determination is yes, execute step S3; if the determination is no, execute step S4; S3. Calculate the difference between the operating frequency and the grid frequency, and determine whether the difference is less than the frequency regulation reference parameter. If the determination is yes, increase the exhaust gas flow rate from the high-pressure cylinder (1) to the intermediate-pressure cylinder (2), so that under the condition of unchanged work capacity of the high-pressure cylinder (1), reduce the work capacities of the intermediate-pressure cylinder (2) and the low-pressure cylinder (3); if the determination is no, increase the flow rate of the exhaust gas from the high-pressure cylinder (1) into the intermediate-pressure cylinder (2), and reduce the main steam flow rate into the high-pressure cylinder (1), so as to reduce the work capacities of the high-pressure cylinder (1), the intermediate-pressure cylinder (2), and the low-pressure cylinder (3), thereby reducing the operating frequency of the coal-fired power generation unit; S4. Calculate the difference between the grid frequency and the operating frequency, and determine whether the difference is less than the frequency regulation reference parameter. If the determination is yes, reduce the exhaust gas flow rate from the high-pressure cylinder (1) to the intermediate-pressure cylinder (2), so that under the condition of unchanged work capacity of the high-pressure cylinder (1), enhance the work capacities of the intermediate-pressure cylinder (2) and the low-pressure cylinder (3); if the determination is no, reduce the flow rate of the exhaust gas from the high-pressure cylinder (1) into the intermediate-pressure cylinder (2), and increase the main steam flow rate into the high-pressure cylinder (1), so as to enhance the work capacities of the high-pressure cylinder (1), the intermediate-pressure cylinder (2), and the low-pressure cylinder (3), and increase the operating frequency of the coal-fired power generation unit.

2. The method for improving the frequency modulation ability of a coal-fired power generation unit according to claim 1, characterized in that The range of the frequency regulation reference parameter is 0.08~0.12 Hz.

3. A method for improving the frequency regulation ability of a coal-fired power generation unit according to claim 1, characterized in that The grid frequency is 50 Hz stipulated by the state.

4. A method for improving the frequency regulation ability of a coal-fired power generation unit according to claim 1, characterized in that, When adjusting the operating frequency of the coal-fired power generation unit, the inlet temperature of the intermediate-pressure cylinder (2) shall not be higher than 632 °C.

5. A system for improving the frequency regulation ability of a coal-fired power generation unit, characterized in that, A system capable of implementing the method for improving the frequency regulation ability of the coal-fired power generation unit as described in any one of claims 1~4, the system further includes: main steam (7) and reheated steam (8) generated by a boiler (4), a main steam valve (5), and an intermediate-pressure cylinder cooling pipeline valve (6); The outlet of the reheated steam (8) is connected to the inlet of the intermediate-pressure cylinder (2); The outlet of the main steam (7) is connected to the inlet of the high-pressure cylinder (1) through the main steam valve (5). The exhaust outlet of the high-pressure cylinder (1) is divided into two paths. One path is connected to the inlet of the intermediate-pressure cylinder (2) through the intermediate-pressure cylinder cooling pipeline valve (6), and the other path is connected to the inlet of the reheated steam (8) through the inlet of the boiler (4).

6. The system for improving the frequency modulation capacity of a coal-fired power generation unit according to claim 5, characterized in that, The system further includes a high-pressure heater. The extraction outlet of the high-pressure cylinder (1) is connected to the denitration system of the coal-fired power generation unit through the high-pressure heater; when adjusting the operating frequency of the coal-fired power generation unit, the inlet flue gas temperature range of the denitration system is 300~400 °C.

7. A system for improving the frequency regulation ability of a coal-fired power generation unit according to claim 6, characterized in that, The system further includes a deaerator. The extraction outlet of the intermediate-pressure cylinder (2) is connected to the high-pressure heater through the deaerator; when adjusting the operating frequency of the coal-fired power generation unit, the pressure range of the deaerator is 0.5~1.0 MPa.

8. A system for improving the frequency regulation ability of a coal-fired power generation unit according to claim 5, characterized in that, When adjusting the operating frequency of a coal-fired power generation unit, the operating frequency of the coal-fired power generation unit is controlled by adjusting the opening degrees of the main steam valve (5) and the intermediate pressure cylinder cooling pipeline valve (6).

9. A system for improving the frequency regulation ability of a coal-fired power generation unit according to claim 8, characterized in that, When increasing the opening degree of the intermediate pressure cylinder cooling pipeline valve (6), the exhaust gas flow rate flowing from the high-pressure cylinder (1) into the intermediate pressure cylinder (2) increases; when decreasing the opening degree of the intermediate pressure cylinder cooling pipeline valve (6), the exhaust gas flow rate flowing from the high-pressure cylinder (1) into the intermediate pressure cylinder (2) decreases.

10. A system for improving the frequency regulation ability of a coal-fired power generation unit according to claim 8, characterized in that, When increasing the opening degree of the main steam valve (5), the main steam flow rate flowing into the high-pressure cylinder (1) increases; when decreasing the opening degree of the main steam valve (5), the main steam flow rate flowing into the high-pressure cylinder (1) decreases.

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