Thermal unit dynamic reactive power support system based on double-fed system

Abstract

The utility model provides a dynamic reactive power support system of a heat power unit based on a double-fed system. The dynamic reactive power support system of the heat power unit comprises a BEST machine, a water feeding pump and the double-fed system, one end of the BEST machine is connected with one end of the water feeding pump; the BEST machine is used for driving the water feeding pump and adjusting the rotating speed of the water feeding pump when the speed regulation of the double-fed system fails, and the water feeding pump is used for conveying water; the other end of the BEST machine is connected with one end of the double-fed system, and the other end of the double-fed system is connected with one end of the power grid; the double-fed system is used for driving the water feeding pump and providing active power and reactive power for a power grid. According to the utility model, redundant active power is used by the double-fed system for power generation and networking to realize real-time regulation of the rotating speed of the water feeding pump, so that stable water supply of the thermal generator set is ensured. Meanwhile, the doubly-fed system responds to the dynamic reactive power regulation requirement of the power grid, and stable reactive power output of the thermal generator set is ensured. The thermal generator set does not need to frequently participate in reactive power regulation, so that the thermal generator set can operate stably.

Description

Technical Field

[0001] The utility model relates to the technical field of thermal power generation, in particular to a dynamic reactive support system for a thermal unit based on a double-feed system. Background Art

[0002] With the rapid development of thermal power generation technology, including the advancement of coal, natural gas and other thermal power generation technologies, the requirements for power generation efficiency and environmental impact are becoming increasingly higher.

[0003] Modern, high-parameter, large-capacity thermal power generators use small, backpressure extraction steam turbines (BESTs) to drive feedwater pumps. The feedwater pump speed is adjusted by adjusting the BEST inlet valve opening to meet the load requirements of the thermal power generator. To improve BEST efficiency and reduce throttling damage, a coaxial generator is typically used to generate excess steam power and transmit it to the grid. However, frequent grid load fluctuations require thermal power generators to have wide-range active and reactive power regulation capabilities and rapid response capabilities. However, wide-range regulation of the thermal power generator's power output can lead to reduced operational stability.

[0004] Therefore, how to stably operate thermal power generating units has become an urgent problem to be solved in this field. Utility Model Content

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a dynamic reactive power support system for thermal power units based on a double-fed system, the purpose of which is to stabilize the operation of thermal power generating units.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] A dynamic reactive power support system for a thermal power unit based on a double-fed system, the dynamic reactive power support system for the thermal power unit comprising: a BEST machine, a feedwater pump and a double-fed system;

[0008] One end of the BEST machine is connected to one end of the water supply pump; the BEST machine is used to drive the water supply pump and adjust the speed of the water supply pump when the speed regulation of the double-fed system fails. The water supply pump is used to transport water;

[0009] The other end of the BEST machine is connected to one end of the double-fed system, and the other end of the double-fed system is connected to one end of the power grid; the double-fed system is used to drive the water pump and to provide active power and reactive power to the power grid.

[0010] Optionally, the doubly-fed system includes a doubly-fed motor and a bidirectional converter;

[0011] One end of the BEST machine is connected to one end of the doubly-fed motor; the doubly-fed motor is used to drive the water supply pump by adjusting the motor speed;

[0012] The rotor winding of the doubly-fed motor is connected to one end of the bidirectional converter, and the stator winding of the doubly-fed motor is connected to one end of the power grid; the bidirectional converter is used to adjust the speed of the doubly-fed motor and provide active power and reactive power to the power grid;

[0013] The other end of the bidirectional converter is connected to the power grid.

[0014] Optionally, the BEST machine, the water feed pump and the doubly fed system are connected by the same shaft system or through a coupling.

[0015] Optionally, the BEST machine is provided with a steam inlet valve; the steam inlet valve is used to adjust the rotation speed of the water feed pump and improve the operating efficiency of the BEST machine.

[0016] Optionally, the thermal unit dynamic reactive support system further includes: a transformer and a medium-voltage plant power grid;

[0017] The other end of the power grid is connected to one end of the transformer, and the other end of the transformer is connected to one end of the medium-voltage plant power grid; the transformer is used to transmit excess active power to the medium-voltage plant power grid.

[0018] Optionally, the power grid is a low-voltage plant power grid.

[0019] Optionally, the thermal unit dynamic reactive support system further includes: an energy management system and a main generator;

[0020] The energy management system is configured to send a reactive power difference instruction to the main generator upon receiving status information of insufficient reactive power compensation sent by the double-fed system;

[0021] The main generator is used to perform reactive power compensation on the medium-voltage auxiliary power grid according to the reactive power difference instruction when receiving the reactive power difference instruction.

[0022] Optionally, the thermal unit dynamic reactive support system further includes: a power plant;

[0023] The energy management system is configured to send the reactive power compensation instruction to the double-fed system after receiving the reactive power compensation instruction sent by the external power grid;

[0024] The double-fed system is used to adjust the reactive power output by the power plant to compensate the medium-voltage plant power grid when receiving the reactive compensation instruction.

[0025] Optionally, the thermal unit dynamic reactive support system further includes: a boiler;

[0026] The water feed pump is connected to the boiler; the boiler is used to heat water.

[0027] Optionally, the BEST machine is provided with a steam extraction port and a steam exhaust port.

[0028] The technical solution provided by the present invention is a dynamic reactive power support system for a thermal power unit, comprising: a BEST machine, a feedwater pump, and a double-fed system; one end of the BEST machine is connected to one end of the feedwater pump; the BEST machine is used to drive the feedwater pump and, if the double-fed system's speed regulation fails, to adjust the speed of the feedwater pump, which is used to transport water; the other end of the BEST machine is connected to one end of the double-fed system, which is connected to one end of the power grid; the double-fed system is used to drive the feedwater pump and to provide active power and reactive power to the power grid. In the present invention, the double-fed system generates excess active power and transmits it to the grid to achieve real-time adjustment of the feedwater pump's speed, ensuring stable water supply to the thermal power unit. Simultaneously, the double-fed system responds to the power grid's dynamic reactive power regulation requirements, ensuring stable reactive power output from the thermal power unit. This eliminates the need for frequent reactive power regulation for the thermal power unit, enabling stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0030] Figure 1 A schematic diagram of a first architecture of a dynamic reactive power support system for a thermal power unit based on a double-fed system provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of a second architecture of a dynamic reactive power support system for a thermal power unit based on a double-fed system provided in an embodiment of the present application;

[0032] Figure 3 A schematic diagram of a third architecture of a dynamic reactive power support system for a thermal power unit based on a double-fed system provided in an embodiment of the present application;

[0033] Figure 4 A fourth schematic diagram of a dynamic reactive power support system for a thermal unit based on a double-fed system provided in an embodiment of the present application;

[0034] Figure 5A fifth schematic diagram of a dynamic reactive power support system for a thermal unit based on a doubly-fed system provided in an embodiment of the present application;

[0035] Figure 6 This is a sixth architectural diagram of a dynamic reactive power support system for a thermal unit based on a doubly-fed system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] In the present invention, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0038] like Figure 1 As shown, an embodiment of the present invention provides a schematic diagram of the architecture of a dynamic reactive power support system for a thermal power unit based on a double-fed system. The dynamic reactive power support system for the thermal power unit includes: a BEST machine 11, a feedwater pump 12 and a double-fed system 13.

[0039] One end of the BEST machine 11 is connected to one end of the water supply pump 12 .

[0040] The BEST machine 11 is used to drive the water supply pump 12 and adjust the speed of the water supply pump 12 when the speed regulation of the double-fed system 13 fails. The water supply pump 12 is used to transport water.

[0041] It should be noted that the BEST machine 11 does not participate in speed regulation under normal circumstances, or when the BEST machine 11 has no steam source, the water feed pump is regulated by the double feed system 13. When the speed regulation of the double feed system 13 fails and cannot drive the water feed pump 12, the BEST machine 11 serves as a supplementary speed regulation means to drive the water feed pump.

[0042] The surplus power after the BEST machine 11 is delivered to the water feed pump 12 can be used to generate electricity and connect to the grid, thus reducing the plant's electricity consumption rate and increasing power generation revenue.

[0043] Further, see Figure 2 The BEST machine 11 is provided with a steam inlet valve 21 .

[0044] The steam inlet valve 21 is used to adjust the rotation speed of the water feed pump 12 and improve the operating efficiency of the BEST machine 11 .

[0045] It is understandable that when the dual-fed system 13 drives the feedwater pump 12 , the steam inlet valve 21 is fully opened or maintains a relatively large opening to reduce the loss of the steam inlet airflow, thereby improving the operating efficiency of the BEST machine 11 .

[0046] In addition, the BEST machine 11 can operate under rated design conditions with high thermal efficiency. Due to the stable operating conditions, the service life of the BEST machine 11 is increased.

[0047] Further, combined Figure 2 For the contents shown, see Figure 3 The BEST machine 11 is provided with a steam extraction port 31 and a steam exhaust port 32 .

[0048] The steam extraction port is used to extract part of the steam from the BEST machine 11 ; and the steam exhaust port discharges unnecessary steam from the BEST machine 11 .

[0049] Optionally, the steam extraction port and the steam inlet can be connected to a heater or a heat network. The number of steam extraction stages of the steam extraction port can be set according to actual conditions.

[0050] It is understood that by adjusting the opening degree of the steam extraction port, the steam flow rate in the BEST machine 11 can be adjusted, thereby controlling the load of the BEST machine 11. When the load decreases or needs to be adjusted, the steam extraction port can reduce the steam flow rate in the BEST machine 11 to avoid overloading or overloading of the BEST machine 11.

[0051] It should be noted that when the load of the BEST machine 11 is reduced or the steam pressure needs to be reduced, the steam pressure inside the BEST machine 11 can be adjusted through the exhaust port to prevent the adverse effects of excessively high or low pressure on the BEST machine 11.

[0052] The other end of the BEST machine 11 is connected to one end of a double-fed system 13 , and the other end of the double-fed system 13 is connected to one end of a power grid 14 .

[0053] The double-fed system 13 is used to drive the water supply pump 12 and to provide active power and reactive power to the power grid 14 .

[0054] It is understandable that the double-fed system 13 can provide active power to the grid 14, and can also absorb active power to drive the feedwater pump 12. In particular, during the cold start of the unit, the feedwater pump 12 is driven by the double-fed system 13.

[0055] Optionally, the double-fed system 13 can provide inductive or capacitive reactive power to the power grid 14, increase the dynamic voltage support means of the generator set, and alleviate the contradiction between the generator set's responsive voltage support and stable economic operation.

[0056] It should be noted that the BEST machine 11, the feedwater pump 12 and the doubly fed system 13 are connected by the same shaft system or through a coupling.

[0057] Further, combined Figure 3 For the contents shown, see Figure 4 The doubly-fed system 13 includes a doubly-fed motor 41 and a bidirectional converter 42 .

[0058] One end of the BEST machine 11 is connected to one end of the doubly-fed electric machine 41 .

[0059] The doubly-fed motor 41 is used to drive the water pump 12 by adjusting the motor speed.

[0060] It is understandable that when the BEST machine 11 has no steam source, the doubly-fed motor 41 operates in the motor mode, adjusts the motor speed, and drives the water feed pump 12 to operate.

[0061] It should be noted that the BEST machine 11 does not participate in speed regulation normally, and only participates when a speed regulation failure occurs in the doubly fed generator 41. The feedwater pump speed is adjusted by adjusting the opening of the steam inlet valve 21 to change the feedwater pump load power.

[0062] In addition, when the output mechanical power of the BEST machine 11 is greater than the load power consumed by the water feed pump 12 , the remaining power of the shaft system is converted into electric power by the doubly-fed motor 41 and transmitted to the grid 14 .

[0063] The rotor winding of the doubly-fed generator 41 is connected to one end of the bidirectional converter 42 , and the stator winding of the doubly-fed generator 41 is connected to one end of the power grid 14 .

[0064] The bidirectional converter 42 is used to adjust the rotation speed of the doubly-fed generator 41 and provide active power and reactive power to the power grid 14 .

[0065] It can be understood that the rotor winding of the doubly fed motor 41 is connected to the bidirectional converter 42, and the electrical part of the rotor winding realizes excitation. The power difference between the BEST machine 11 and the water supply pump 12 is absorbed or provided through excitation regulation, and the differential power is exchanged with the power grid 14, thereby realizing load regulation of the water supply pump 14.

[0066] In addition, the operation of the doubly fed generator 41 as a motor in motor mode and the operation of generating electricity and connecting to the grid are automatically controlled by the bidirectional converter 42 by exciting the rotor of the doubly fed generator 41. The goal is to adjust the operating speed of the water supply pump 12 to match the water supply demand of the unit and generate electricity and connect to the grid with the remaining power, thereby reducing the plant's power consumption rate and increasing the income from electricity sales.

[0067] The other end of the bidirectional converter 42 is connected to the power grid 14 .

[0068] It should be noted that when the grid 14 requires voltage regulation, the bidirectional converter 42 can change the magnitude of the excitation current to change the voltage output of the doubly-fed generator 41. At the same time, the grid-side portion of the bidirectional converter 42 can also send reactive power to the grid 14 to regulate the voltage of the grid 14. When the reactive power provided by the doubly-fed generator 41 and the bidirectional converter 42 is insufficient to meet the dynamic voltage regulation requirements of the grid 41, the voltage regulation function of the generator set supplements this, thereby improving the reactive power response capability of the generator set and ensuring efficient, stable and economical operation of the generator set.

[0069] Further, combined Figure 4 For the contents shown, see Figure 5 The dynamic reactive power support system of the thermal power unit further includes: a transformer 51 and a medium-voltage plant power grid 52.

[0070] The other end of the power grid 14 is connected to one end of a transformer 51 , and the other end of the transformer 51 is connected to one end of a medium-voltage auxiliary power grid 52 .

[0071] The transformer 51 is used to transmit excess active power to the medium-voltage auxiliary power grid 52 .

[0072] Optionally, the 14th power grid is a low-voltage plant power grid.

[0073] It should be noted that the doubly-fed generator 41 can be connected to the low-voltage plant power grid. While reducing the cost of the doubly-fed system 13, the generated power can also be consumed locally, improving power efficiency. When there is surplus power, it is sent to the medium-voltage plant power grid 52 by the transformer 51, which can effectively reduce the plant power consumption rate.

[0074] Further, combined Figure 5 For the contents shown, see Figure 6 The dynamic reactive power support system of the thermal unit also includes: an energy management system 61 and a main generator 62.

[0075] The energy management system 61 is configured to send a reactive power difference instruction to the main generator 62 upon receiving status information of insufficient reactive power compensation sent by the double-fed system.

[0076] The reactive power coordination control between the double-fed system 13 and the main generator 62 is achieved through the energy management system 61 .

[0077] It is understandable that when the reactive power compensation capability of the double-fed system 13 is insufficient, the insufficient capability status will be sent to the energy management system 61, and the energy management system 61 will send the reactive power difference instruction to the main generator for reactive power difference compensation.

[0078] The main generator 62 is used to perform reactive power compensation on the medium-voltage auxiliary power grid 14 according to the reactive power difference instruction when receiving the reactive power difference instruction.

[0079] Furthermore, the dynamic reactive support system of the thermal unit also includes: a power plant.

[0080] The energy management system 61 is configured to send a reactive power compensation instruction to the double-fed system 13 upon receiving the reactive power compensation instruction sent by the external power grid.

[0081] The energy management system 10 adjusts the reactive power output of the power plant through reactive compensation instructions (ie, AVC instructions) sent by the external power grid.

[0082] The double-fed system 13 is used to adjust the reactive power output by the power plant to compensate the medium-voltage auxiliary power grid 14 when receiving a reactive power compensation instruction.

[0083] Furthermore, the dynamic reactive support system of the thermal unit also includes: a boiler.

[0084] The feed water pump 12 is connected to the boiler.

[0085] Among them, the boiler is used to heat water, that is, to heat water to a high temperature or high pressure state.

[0086] It is understandable that when the doubly-fed generator 41 operates in motor mode to drive the feedwater pump 12, it can operate as an electric feedwater pump when the generator set has no starting steam source to ensure that the boiler can be normally filled with water.

[0087] In summary, the dual-fed system drives the feedwater pump, thereby regulating its speed to ensure normal boiler water filling. The BEST unit is only used to regulate the feedwater pump speed in the event of a dual-fed system failure. In this utility model, excess steam power is generated and fed to the grid through the dual-fed system. This avoids load fluctuations and, consequently, does not affect the thermal power generator set, ensuring stable operation of the thermal power generator set.

[0088] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0089] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dynamic reactive power support system for thermal power units based on a double-fed system, characterized in that: The dynamic reactive power support system of the thermal power unit includes: BEST machine, feedwater pump, double-fed system, transformer, medium-voltage plant power grid, energy management system and main generator; One end of the BEST machine is connected to one end of the water supply pump; the BEST machine is used to drive the water supply pump and adjust the speed of the water supply pump when the speed regulation of the double-fed system fails. The water supply pump is used to transport water; The other end of the BEST machine is connected to one end of the double-fed system, and the other end of the double-fed system is connected to one end of the power grid; the double-fed system is used to drive the water pump and to provide active power and reactive power to the power grid; The other end of the power grid is connected to one end of the transformer, and the other end of the transformer is connected to one end of the medium-voltage power grid; the transformer is used to transmit excess active power to the medium-voltage power grid; The energy management system is configured to send a reactive power difference instruction to the main generator upon receiving status information of insufficient reactive power compensation sent by the double-fed system; The main generator is used to perform reactive power compensation on the medium-voltage auxiliary power grid according to the reactive power difference instruction when receiving the reactive power difference instruction; Wherein, the doubly-fed system includes a doubly-fed generator and a bidirectional converter; One end of the BEST machine is connected to one end of the doubly-fed motor; the doubly-fed motor is used to drive the water supply pump by adjusting the motor speed; The rotor winding of the doubly-fed motor is connected to one end of the bidirectional converter, and the stator winding of the doubly-fed motor is connected to one end of the power grid; the bidirectional converter is used to adjust the speed of the doubly-fed motor and provide active power and reactive power to the power grid; The other end of the bidirectional converter is connected to the power grid.

2. The system according to claim 1, wherein: The BEST machine, the water feed pump and the double-fed system are connected by the same shaft system or through a coupling.

3. The system according to claim 1, wherein: The BEST machine is provided with a steam inlet valve; the steam inlet valve is used to adjust the rotation speed of the water feed pump and improve the operating efficiency of the BEST machine.

4. The system according to claim 1, wherein: The power grid is a low-voltage plant power grid.

5. The system according to claim 1, wherein: The thermal unit dynamic reactive support system further includes: a power plant; The energy management system is configured to send the reactive power compensation instruction to the double-fed system after receiving the reactive power compensation instruction sent by the external power grid; The double-fed system is used to adjust the reactive power output by the power plant to compensate the medium-voltage plant power grid when receiving the reactive compensation instruction.

6. The system according to claim 1, wherein: The thermal unit dynamic reactive support system further includes: a boiler; The water feed pump is connected to the boiler; the boiler is used to heat water.

7. The system according to claim 1, wherein: The BEST machine is provided with a steam extraction port and a steam exhaust port.

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