A peak regulation and frequency modulation heat supply system for a thermal power plant

Abstract

This application proposes a peak-shaving and frequency-regulating heating system for a thermal power plant, comprising: a high-pressure bypass pipeline (22) connected to the steam outlet of a steam boiler (1), the outlet end of which is connected to the cold section of a reheater (2); a low-pressure extraction steam pipeline (21) connected to the hot section of the reheater (2) at its inlet end, the outlet end of which is connected to a heating network heater or directly connected to a steam supply pipeline; an electric boiler (17) electrically connected to the outlet of a generator (6) or the outlet of a main transformer (7), using electrical energy to generate steam / hot water to supply the heating network and / or a heat storage device (18); the input end of the heat storage device (18) is connected to the output end of the electric boiler (17) to temporarily store the steam / hot water generated by the electric boiler (17). This application utilizes the modification of the high and low bypasses of the thermal power unit to supply steam externally, while using the electric boiler (17) for peak-shaving and frequency regulation, directly supplying heat externally or storing it in the heat storage device (18), thus satisfying the heating needs while ensuring the peak-shaving and frequency regulation performance of the unit.

Description

Technical Field

[0001] This application belongs to the technical field of peak shaving and frequency regulation in thermal power plants, and particularly relates to a peak shaving and frequency regulation heating system for thermal power plants. Background Technology

[0002] Traditional thermal power plants, especially combined heat and power (CHP) units responsible for urban heating, typically use steam extracted from each stage of the turbine as a heat source, which is then used to heat the circulating water in the heating network. This "heat-driven power generation" operating mode achieves good comprehensive energy utilization during the winter heating season. However, with the increasing proportion of intermittent renewable energy sources such as wind power and photovoltaics in my country's power system, the power grid is placing increasingly higher demands on the peak-shaving capacity of coal-fired units.

[0003] In existing technologies, the common method to maintain heating under low load is to increase boiler combustion to raise the main steam pressure. However, this causes the turbine to operate outside its design conditions, resulting in poor economic efficiency and limited adjustment range. Furthermore, when the unit operates at low load, the steam flow through the reheater is significantly reduced, which can easily lead to overheating of the reheater tube walls, posing a threat to the safe operation of the equipment.

[0004] On the other hand, electric boilers, as load regulating devices that can respond quickly and accurately, have been attempted for peak shaving in thermal power plants. However, they are usually used as independent peak shaving units and have not been deeply coupled with the unit's steam circulation system and heating system. For example, if the heat energy generated by the electric boiler cannot be effectively utilized during the non-heating season, it will result in energy waste. Utility Model Content

[0005] This application provides a peak-shaving and frequency-regulating heating system for a thermal power plant, wherein the thermal power plant includes a steam boiler, a reheater, a steam turbine, and a generator, and the steam turbine has a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder connected in sequence. The system includes: The high-pressure bypass pipeline has its inlet end connected to the steam outlet of the steam boiler, and its outlet end connected to the cold reheat pipeline between the high-pressure cylinder exhaust outlet and the cold section of the reheater; a second regulating valve is installed on the high-pressure bypass pipeline. The low-pressure extraction steam pipeline has its inlet end connected to the hot section of the reheater, and its outlet end connected to the heating network heater or directly connected to the steam supply pipeline. The low-pressure extraction steam pipeline is equipped with a first regulating valve, which is used to control the flow rate. An electric boiler, electrically connected to the generator outlet or the main transformer outlet, is used to generate steam / hot water using electrical energy to supply the heating network and / or thermal storage devices. A heat storage device, whose input end is connected to the output end of an electric boiler, is used to temporarily store the steam / hot water produced by the electric boiler.

[0006] Furthermore, the electric boiler is an electrode boiler used for producing hot water, comprising: a sealed outer cylinder, and three-phase electrodes and a neutral electrode disposed inside the outer cylinder; The three-phase electrodes penetrate from the top of the outer cylinder into the internal space, while the neutral electrode is located inside the outer cylinder or on its inner wall; among them... Each phase electrode in the three-phase system is equipped with a protective shield that covers part or all of its surface. The protective shield is an insulator and is connected to a lifting mechanism located on the inner wall of the outer cylinder. The shield can move up and down along the phase electrode to adjust the exposed area of ​​the phase electrode in the water, thereby responding to the frequency regulation of the power grid.

[0007] Furthermore, an electric boiler is an electrode-type boiler used to produce steam, comprising: an outer cylinder and an inner cylinder; The bottom of the outer cylinder is equipped with an insulated water supply port, as well as an internal circulation pump and internal circulation pipe that transport water from the bottom of the outer cylinder to the upper inner cylinder; The inner cylinder has a three-phase electrode at the top, which is connected to an external power source. The inner cylinder sidewall is electrically connected to a neutral electrode. The three-phase electrode and the neutral electrode can be submerged in water to directly heat the water and generate steam. The outer cylinder has an insulated steam port on the upper side. A water level gauge is installed inside the inner cylinder; The water level in the inner cylinder is monitored and the flow rate of the internal circulation pump is controlled to adjust the contact area between the three-phase electrodes and the water in the inner cylinder, thereby responding to the frequency regulation of the power grid.

[0008] Furthermore, the heat storage device is a water storage heat storage tank.

[0009] Furthermore, a desuperheater is installed on the high-pressure bypass pipeline to deheat the high-pressure steam from the steam boiler outlet before sending it back to the cold section of the reheater.

[0010] Furthermore, the desuperheater is a water spray desuperheater, which includes a cylindrical cavity, a water spray pipe, and a nozzle; High-pressure bypass pipelines are connected to both ends of the cylindrical cavity; One end of the water spray pipe passes through the outer wall of the cylindrical cavity and connects to the nozzle, while the other end is used to connect to the external water supply pipeline.

[0011] Furthermore, the system also includes: A pressure sensor is installed on the cold reheat pipeline between the exhaust outlet of the high-pressure cylinder and the cold section of the reheater to monitor the exhaust pressure of the high-pressure cylinder. The first regulating valve is connected to the DCS system of the thermal power plant via a control line to control the amount of low-pressure steam extraction for heating. The second regulating valve and pressure sensor are connected to the DCS system of the thermal power plant via control lines to control the flow rate of the high-pressure bypass pipeline and regulate the exhaust pressure of the high-pressure cylinder.

[0012] Furthermore, the condensate feedwater pipeline of the steam turbine is sequentially equipped with a condenser or air cooler, a condensate pump, a low-pressure heater, a deaerator, and a high-pressure heater.

[0013] The above-mentioned technical solution of this utility model has at least the following beneficial technical effects: (1) This application utilizes the modification of the high and low bypass of the thermal power unit to supply heat to the outside, and at the same time uses the electric boiler for peak shaving and frequency regulation, so that the generated heat is directly supplied to the outside or stored in the heat storage device, thus solving the problem that the heating unit meets the heating needs while ensuring the peak shaving and frequency regulation performance of the unit.

[0014] (2) When deep peak shaving or frequency regulation is required, the electric boiler 17 can quickly consume electrical energy, participate in the unit's peak shaving and frequency regulation, and convert electrical energy into heat energy.

[0015] (3) Heating season: Steam / hot water generated by electric boilers can be directly fed into steam supply pipelines or enter the heating network, or temporarily stored in heat storage devices before being fed into steam supply pipelines / heating networks, further enhancing heating capacity.

[0016] During the non-heating season: Steam / hot water generated by frequency regulation of electric boilers is stored in heat storage devices or sent to condensate feedwater pipelines through recovery pipelines, so that electrical energy is recovered in the form of heat energy to the thermal cycle of steam boiler and steam turbine, avoiding energy waste; hot water temporarily stored in heat storage devices can be sent to condensate feedwater pipelines. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a thermal power plant peak-shaving and frequency-regulating heating system in one embodiment of this application.

[0019] Figure 2 This is a schematic diagram of the structure of a hot water type electric boiler in one embodiment of this application.

[0020] Figure 3 This is a schematic diagram of the structure of a steam-type electric boiler in one embodiment of this application.

[0021] in, Figure 1-3 The correspondence between the reference numerals and the component names in the attached drawings is as follows: 1. Steam boiler; 2. Reheater; 3. High-pressure cylinder; 4. Medium-pressure cylinder; 5. Low-pressure cylinder; 6. Generator; 7. Main transformer; 8. Condenser or air cooler; 9. Condensate pump; 10. Low-pressure heater; 11. Deaerator; 12. High-pressure heater; 13. Second regulating valve; 14. Desuperheater; 15. First regulating valve; 16. First gate valve; 17. Electric boiler; 171. Outer cylinder; 1711. Insulated water supply port; 1712. Sewage outlet; 1713. Internal circulation pump; 1714. Internal circulation pipe; 1715. Resistance heater; 1716. Insulated steam port; 1717. Insulated water outlet; 1718. Protective shield; 1719. Insulator; 172. Inner cylinder; 1721. Three-phase electrode; 1722. Neutral electrode; 18. Thermal storage device.

[0022] 21. Low-pressure extraction steam pipeline; 22. High-pressure bypass pipeline; 23. Condensate feedwater pipeline; 24. Hot reheat pipeline; 25. Cold reheat pipeline. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details are presented in the various embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the various embodiments below is for ease of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0024] To solve the above problems, such as Figure 1 As shown, one embodiment of this application provides a peak-shaving and frequency-regulating heating system for a thermal power plant. The thermal power plant includes a steam boiler 1, a reheater 2, a steam turbine, and a generator 6. The steam boiler 1 can be a coal-fired boiler, a biomass boiler, or a gas-fired boiler that heats feedwater to produce steam. Taking a coal-fired boiler as an example, the coal-fired boiler provides high-pressure steam to the steam turbine, which uses the steam to generate mechanical energy to drive the generator 6 to generate electricity. The generator 6 is connected to a main transformer 7. The steam turbine has a high-pressure cylinder 3, an intermediate-pressure cylinder 4, and a low-pressure cylinder 5 connected in sequence. The coal-fired boiler is equipped with a reheater 2. The cold section of the reheater 2 is connected to a portion of the exhaust port of the high-pressure cylinder 3 via a cold reheat pipeline 25, transporting the steam after the high-pressure cylinder has completed its work to the cold section of the reheater 2. The hot section of the reheater 2 is connected to the steam inlet of the intermediate-pressure cylinder 4 via a hot reheat pipeline 24, transporting the reheated hot reheat steam to the intermediate-pressure cylinder 4 to perform work. The peak-shaving and frequency-regulating heating system for a thermal power plant proposed in this embodiment specifically includes: The high-pressure bypass pipeline 22 has its inlet end connected to the steam outlet of the steam boiler 1 and its outlet end connected to the cold reheat pipeline 25, which is used to supply a portion of the high-pressure steam prepared by the steam boiler 1 to the cold section of the reheater 2; a second regulating valve 13 is provided on the high-pressure bypass pipeline 22 to control the flow rate of this portion of high-pressure steam.

[0025] The low-pressure extraction steam pipeline 21 connects to the hot section of reheater 2 at its inlet and to the heating network heater at its outlet, delivering a portion of the hot reheat steam to the heating network or to the steam supply pipeline. The low-pressure extraction steam pipeline 21 is equipped with a first regulating valve 15 for controlling the flow rate, and a first gate valve 16 for controlling the opening and closing of the pipeline. The heating network heater, used by thermal power plants, exchanges heat between the extracted steam and the heating return water.

[0026] The electric boiler 17 is electrically connected to the outlet of the generator 6 or the outlet of the main transformer 7, and is also connected to the water supply pipeline. It is used to generate steam / hot water using electrical energy to directly supply it to the heating network, or to store the generated steam / hot water in the heat storage device 18. The steam / hot water input end of the heat storage device 18 is connected to the steam / hot water output end of the electric boiler 17 for temporary storage of the steam / hot water generated by the electric boiler 17.

[0027] Optionally, the output end of the heat storage device 18 for storing hot water is connected to the condensate feedwater pipeline 23 of the steam turbine, and is also connected to the heating network; during operation, the hot water stored in the heat storage device 18 can be fed into the condensate feedwater pipeline 23 or flow into the heating network as needed.

[0028] The output end of the heat storage device 18 for storing steam is connected to the steam side of the low-pressure heater 10 or the deaerator 11 installed on the condensate feedwater pipeline 23, and is also connected to the heating network.

[0029] Optionally, the output end of the electric boiler 17 that produces hot water is connected to the condensate feedwater pipeline 23 and to the heating network; The output end of the electric boiler 17 that generates steam is connected to the heating network and is connected to the steam side of the low-pressure heater 10 or the deaerator 11 installed on the condensate feedwater pipeline 23.

[0030] This application, based on the steam turbine extraction system of a traditional thermal power plant, sets up a high-pressure bypass pipeline 22, a low-pressure extraction pipeline 21, and an electric boiler 17. It can extract and regulate the high-pressure main steam from the steam boiler 1, the hot reheat steam from the reheater 2, and the surplus electricity from the generator 6 generated by the electric boiler 17 to produce steam / hot water for temporary storage or connection to a heating network for external users. This application utilizes the modification of the high and low pressure bypasses of the thermal power unit for external heat supply, while simultaneously using the electric boiler 17 for peak shaving and frequency regulation. The generated heat is directly supplied externally or stored in the heat storage device 18, solving the problem of the heating unit meeting heating requirements while ensuring the unit's peak shaving and frequency regulation performance.

[0031] In one embodiment of this application, the generator 6 is connected to an auxiliary transformer at its outlet, which supplies power to the electric boiler 17. The electric boiler 17 can be an electrode boiler or a resistance hot water boiler.

[0032] In one alternative embodiment, such as Figure 2 As shown, the electrode boiler used for hot water preparation has a protective cover on the outermost side. The main structure of the electrode boiler includes a sealed outer cylinder 171 and electrodes disposed within the outer cylinder 171. The electrodes include a three-phase electrode 1721 and a neutral electrode 1722. The three-phase electrode 1721 is connected to a power supply line. Figure 2 The diagram shows one phase electrode of the three-phase electrode 1721. The three-phase electrode 1721 extends from the top of the outer cylinder 171 into the internal space. An insulator 1719 is provided at the connection between the three-phase electrode 1721 and the outer cylinder 171. The neutral electrode 1722 is located inside or on the inner wall of the outer cylinder 171 and is electrically connected to the outer cylinder 171. Each phase electrode of the three-phase electrode 1721 is provided with a protective shield 1718 that can cover part or all of its surface. The protective shield 1718 is made of insulating material and is connected to a lifting mechanism located on the inner wall of the outer cylinder 171. The lifting mechanism can be electrically or mechanically driven. Driven by the lifting mechanism, the protective shield 1718 can move up and down along the phase electrode to adjust the exposed area of ​​the phase electrode, thereby adjusting the contact area between the phase electrode and the water inside the outer cylinder 171, ultimately regulating the boiler's power and enabling rapid response to the frequency regulation requirements of the power grid. The three-phase electrode 1721 and the neutral electrode 1722 are located in the upper part of the outer cylinder 171 to facilitate heating the upper layer of water first. The top of the outer cylinder 171 is equipped with an insulated water outlet 1717 and a circulating water pump, and the bottom of the outer cylinder 171 is equipped with an insulated water supply outlet 1711. After water is filled into the outer cylinder 171, the three-phase electrode 1721 (except for the part covered by the protective shield 1718) can be completely submerged in water. When the water level in the outer cylinder 171 is lower than the lowest position of the electrode, the three-phase electrode 1721 and the neutral electrode 1722 lack a conductive medium (water) and automatically disconnect and stop working, so dry burning will not occur.

[0033] In one alternative embodiment, such as Figure 3As shown, the electrode boiler used for steam generation has electrodes submerged in water. The output power is adjusted by regulating the area of ​​the electrodes covered by water, i.e., by adjusting the water level. Its specific structure includes an outer cylinder 171 and an inner cylinder 172 located in the upper part of the outer cylinder 171. The bottom space of the outer cylinder 171 is used to hold water. The bottom of the outer cylinder 171 is equipped with an insulated water supply port 1711, a drain port 1712, and an internal circulation pump 1713 and an internal circulation pipe 1714 that transport water from the bottom of the outer cylinder 171 to the upper inner cylinder 172. The internal circulation pump 1713 is connected to the water at the bottom of the outer cylinder 171, and the internal circulation pump 1713 and the internal circulation pipe 1714 are connected to the outside of the outer cylinder 171. The internal circulation pipe 1714 passes through the bottom of the outer cylinder 171 and the bottom of the inner cylinder 172 to the inside of the inner cylinder, transporting water from the bottom of the outer cylinder 171 to the inside of the inner cylinder 172. A resistance heater 1715 may also be installed inside the outer cylinder 171 for preheating the water at the bottom of the outer cylinder 171. A three-phase electrode 1721 is located at the top inside the inner cylinder 172, connected to an external power supply (multiple sets of three-phase electrodes 1721 are arranged in a circle). Figure 3 The diagram shows one phase electrode of a three-phase electrode 1721. The neutral electrode 1722 is electrically connected to the side wall of the inner cylinder 172 and to the outside of the outer cylinder 171. The three-phase electrode 1721 is submerged in water to directly heat the water and generate steam. The top of the inner cylinder 172 is open, and the upper side of the outer cylinder 171 is provided with an insulated steam port 1716. The steam generated in the inner cylinder 172 flows out from the insulated steam port 1716 of the outer cylinder 171. The insulated steam port 1716 is connected to the heating network and the heat storage device 18, respectively.

[0034] A water level gauge is installed inside the inner cylinder 172. The flow rate of the internal circulation pump 1713 is controlled and the water level in the inner cylinder 172 is monitored to adjust the contact area between the three-phase electrode 1721 and the water in the inner cylinder 172, thereby adjusting the operating power of the electric boiler 17 and quickly responding to the frequency regulation requirements of the power grid.

[0035] The thermal system of steam boiler 1 and steam turbine unit in thermal power plant has a large inertia and can meet the peak shaving needs, but its response speed to the frequency regulation needs of the power grid is insufficient. After adding electric boiler 17 (rated voltage of 5-20KV), it can quickly consume electrical energy and respond to the rapid response requirements of the power grid frequency regulation by adjusting the operating power. It can also store electrical energy as thermal energy through heat storage device 18.

[0036] Optionally, the electrode boiler can be a submerged high-pressure electrode boiler from APPANI AG of Sweden. The electrode steam boiler used for steam generation is model ETSH 10Mi or ETSH 25Mi. The electrode hot water boiler used for hot water generation is model ETHH 8M or ETHH 12M, with a voltage rating of 10KV and an outlet water temperature of 110℃-150℃.

[0037] In one embodiment of this application, the heat storage device 18 is a commercially available custom-capacity water storage tank. The water storage tank is divided into hot water type and steam type. The hot water type tank can be kept at atmospheric pressure, while the steam type tank is kept at high pressure, allowing steam to be stored in a water-like state. The main structure of the hot water type tank includes a vertical or horizontal circular steel cylinder with elliptical end caps at both ends. The cylinder is externally insulated with rock wool or aluminum silicate fiber. An inlet is located at the top of the cylinder for connection to the electric boiler 17; the outlet at the bottom of the cylinder is connected to the heating network and also to the steam side of the low-pressure heater 10 or the deaerator 11 of the condensate feedwater pipeline 23.

[0038] In one embodiment of this application, a desuperheater 14 is provided on the high-pressure bypass pipeline 22 to deheat the high-pressure steam from the steam outlet of the steam boiler 1 before sending it into the cold section of the reheater 2. Preferably, the desuperheater 14 is a water spray desuperheater, which includes a cylindrical cavity, a water spray pipe, and a nozzle; both ends of the cylindrical cavity are connected to the high-pressure bypass pipeline 22 and fixed by flanges. One end of the water spray pipe passes through the outer wall of the cylindrical cavity and connects to the nozzle, and the other end is used to connect to an external water supply pipeline; the water spray pipe is provided with a regulating valve and a check valve; a sealing sleeve is provided where the water spray pipe passes through the cylindrical cavity to prevent high-pressure steam leakage.

[0039] The optional solutions for peak shaving and frequency regulation of the thermal power plant heating system in this application include: (1) During peak shaving periods, the grid load demand decreases, and the generating units operate at reduced load, resulting in a reduction in the conventional extraction steam for heating. At this time, according to the heating demand, the first regulating valve 15 on the low-pressure extraction steam pipeline 21 is adjusted to extract sufficient steam from the hot section of the reheater 2 and supply it to the heating network through the steam supply pipeline to supplement the insufficient extraction steam caused by the decrease in unit load. At the same time, the opening of the second regulating valve 13 on the high-pressure bypass pipeline 22 is adjusted to allow some of the high-pressure steam from the steam boiler 1 to be cooled to the allowable parameters of the cold section of the reheater 2 by water spraying through the desuperheater 14, and then introduced into the cold section of the reheater 2 to maintain its flow rate and temperature, avoid dry burning or overheating of the reheater 2, and ensure the safe operation of the reheater 2.

[0040] (2) When deep peak shaving or frequency regulation is required, the electric boiler 17 can quickly consume electrical energy, participate in the unit's peak shaving and frequency regulation, and convert electrical energy into heat energy.

[0041] (3) Heating season: The steam / hot water generated by the electric boiler 17 can be directly fed into the steam supply pipeline, or enter the heating network, or be temporarily stored in the heat storage device 18 and then fed into the steam supply pipeline or heating network to further enhance the heating capacity.

[0042] During the non-heating season: Steam / hot water generated by frequency regulation of electric boiler 17 is stored in heat storage device 18, or sent to condensate feed water pipeline 23 through recovery pipeline, so as to recover electrical energy in the form of heat energy to the thermal cycle of steam boiler 1 and steam turbine, avoiding energy waste; hot water temporarily stored in heat storage device 18 can be sent to condensate feed water pipeline 23.

[0043] In one embodiment of this application, the system further includes a pressure sensor disposed on the cold reheat pipeline 25 between the exhaust outlet of the high-pressure cylinder 3 and the cold section of the reheater 2, for monitoring the exhaust pressure of the high-pressure cylinder.

[0044] Optionally, the first regulating valve 15 is connected to the DCS system of the thermal power plant via a control line to control the low-pressure steam extraction heating capacity; the second regulating valve 13 and the pressure sensor are connected to the DCS system of the thermal power plant via control lines to control the flow rate of the high-pressure bypass pipeline 22 and regulate the exhaust pressure of the high-pressure cylinder.

[0045] In one embodiment of this application, the condensate feedwater pipeline 23 of the steam turbine is sequentially provided with a condenser or air cooler 8, a condensate pump 9, a low-pressure heater 10, a deaerator 11, and a high-pressure heater 12.

[0046] In the description of this utility model, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this utility model, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of this application and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this application should be included within the protection scope of this application. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A peak-shaving and frequency-regulating heating system for a thermal power plant, wherein, A thermal power plant comprises a steam boiler (1), a reheater (2), a steam turbine, and a generator (6). The steam turbine has a high-pressure cylinder (3), an intermediate-pressure cylinder (4), and a low-pressure cylinder (5) connected in sequence. The plant is characterized by including: The high-pressure bypass pipeline (22) has its inlet end connected to the steam outlet of the steam boiler (1) and its outlet end connected to the cold reheat pipeline (25) between the exhaust outlet of the high-pressure cylinder (3) and the cold section of the reheater (2); a second regulating valve (13) is provided on the high-pressure bypass pipeline (22). The low-pressure extraction steam pipeline (21) has its inlet end connected to the hot section of the reheater (2) and its outlet end connected to the heat network heater or directly connected to the steam supply pipeline. The low-pressure extraction steam pipeline (21) is equipped with a first regulating valve (15), which is used to control the flow rate. An electric boiler (17) is electrically connected to the outlet of a generator (6) or the outlet of a main transformer (7) for generating steam / hot water using electrical energy to supply the heating network and / or a heat storage device (18). A heat storage device (18) is connected at its input end to the output end of an electric boiler (17) for temporarily storing steam / hot water prepared by the electric boiler (17).

2. The peak-shaving and frequency-regulating heating system for thermal power plants according to claim 1, characterized in that, An electric boiler is an electrode boiler used for producing hot water, comprising: a sealed outer cylinder (171), and a three-phase electrode (1721) and a neutral electrode (1722) disposed inside the outer cylinder (171). The three-phase electrode (1721) extends from the top of the outer cylinder (171) into the internal space, and the neutral electrode (1722) is located inside the outer cylinder (171) or on its inner wall; wherein, Each phase electrode in the three-phase electrode (1721) is provided with a protective shield that can cover part or all of its surface. The protective shield is an insulator (1719). The protective shield is connected to a lifting mechanism located on the inner wall of the outer cylinder (171) and can move up and down along the phase electrode to adjust the exposed area of ​​the phase electrode, thereby adjusting the contact area between the phase electrode and the water in the outer cylinder (171), and thus responding to the frequency regulation of the power grid.

3. The peak-shaving and frequency-regulating heating system for thermal power plants according to claim 1, characterized in that, An electric boiler is an electrode-type boiler used to produce steam, comprising: an outer cylinder (171) and an inner cylinder (172). The bottom of the outer cylinder (171) is provided with an insulated water supply port (1711), and an internal circulation pump (1713) and an internal circulation pipe (1714) for transporting water from the bottom of the outer cylinder (171) to the upper inner cylinder (172). The inner cylinder has a three-phase electrode (1721) at the top, which is connected to an external power source. The neutral electrode (1722) is electrically connected to the side wall of the inner cylinder (172). The three-phase electrode (1721) and the neutral electrode (1722) can be submerged in water to directly heat water and generate steam. The outer cylinder (171) has an insulated steam port (1716) on the upper side. A water level gauge is installed inside the inner cylinder (172); the water level in the inner cylinder (172) is monitored and the flow rate of the internal circulation pump (1713) is controlled to adjust the contact area between the three-phase electrode (1721) and the water in the inner cylinder (172), thereby responding to the frequency regulation of the power grid.

4. The peak-shaving and frequency-regulating heating system for thermal power plants according to claim 1, characterized in that, The heat storage device (18) is a water storage heat storage tank.

5. The peak-shaving and frequency-regulating heating system for thermal power plants according to claim 1, characterized in that, A desuperheater (14) is installed on the high-pressure bypass pipeline (22) to deheat the high-pressure steam from the steam outlet of the steam boiler (1) and send it back to the cold section of the reheater (2).

6. The peak-shaving and frequency-regulating heating system for thermal power plants according to claim 5, characterized in that, The desuperheater (14) is a water spray desuperheater (14), which includes a cylindrical cavity, a water spray pipe and a nozzle; High-pressure bypass pipelines are connected to both ends of the cylindrical cavity (22); One end of the water spray pipe passes through the outer wall of the cylindrical cavity and connects to the nozzle, while the other end is used to connect to the external water supply pipeline.

7. The peak-shaving and frequency-regulating heating system for thermal power plants according to claim 1, characterized in that, Also includes: A pressure sensor is installed on the cold reheat pipeline (25) between the exhaust outlet of the high-pressure cylinder (3) and the cold section of the reheater (2) to monitor the exhaust pressure of the high-pressure cylinder. The first regulating valve (15) is connected to the DCS system of the thermal power plant through the control line to control the amount of low-pressure steam extraction for heating. The second regulating valve (13) and the pressure sensor are connected to the DCS system of the thermal power plant through control lines to control the flow rate of the high-pressure bypass pipeline (22) and regulate the exhaust pressure of the high-pressure cylinder.

8. The peak-shaving and frequency-regulating heating system for thermal power plants according to any one of claims 1-7, characterized in that, The condensate feedwater pipeline (23) of the steam turbine is equipped with a condenser or air cooler (8), a condensate pump (9), a low-pressure heater (10), a deaerator (11), and a high-pressure heater (12) in sequence.

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