A control device and method for eliminating the protection refusal of a primary air fan of a thermal power unit

Abstract

The application provides a control device and method for eliminating the protection refusal of primary air fan of thermal power generating unit, relates to the technical field of thermal power generation, and forms a primary air fan protection shutdown condition SPPRO module through a 6KV low voltage protection or a main fuel trip MFT hard wire loop on the left side of the basic driving level of the motor; a shutdown instruction module is arranged, the shutdown instruction module is connected with the right side STOP port of the basic driving level of the motor, a trigger signal of the primary air fan protection shutdown condition SPPRO module is received through the STOP port, the shutdown instruction module comprises a frequency converter stop port and a 6KV switch jump port; a frequency conversion mode and a power frequency mode output port are added on the left side of the driving level, and the shutdown instruction is taken as an AND output to the frequency converter stop port and the 6KV switch jump port in the frequency conversion mode and the power frequency mode, so that the technical problem of how to ensure the reliability of the protection logic device and prevent the misoperation and refusal of the main auxiliary machine protection is solved.

Description

Technical Field

[0001] This invention relates to the technical field of thermal power generation, specifically to a control device and method for eliminating the failure of primary air turbine protection in thermal power units. Background Technology

[0002] Large thermal power units with an installed capacity of 300MW-1000MW are typically equipped with two primary air fans operating in parallel. As an important component of the boiler flue gas system, the primary air fans are divided into two paths at the outlet. One path is heated by an air preheater to become hot primary air, which is used for drying and ventilation of the coal mill, and transports the ground coal powder to the boiler furnace burners. The other path is not heated and is called cold primary air. The cold primary air and hot primary air are mixed at the inlet of the coal mill to regulate the inlet and outlet temperatures of the coal mill, and also to provide ventilation power for the coal mill.

[0003] Conventional primary air turbines operate at 6 kV, classifying them as high-energy-consuming equipment. To conserve energy and reduce consumption, most power generation companies are converting their turbine motors from "power frequency" to "variable frequency" to lower energy consumption, save plant power, and improve the unit's economic efficiency. To support the national dual-carbon goals, the power system will significantly increase the proportion of green energy generation. However, green energy sources such as wind and solar power cannot operate continuously and stably; flexible peak-shaving by thermal power units is necessary to ensure the grid's safety and continuity. During deep flexible peak-shaving by thermal power units, major auxiliary equipment such as primary air turbines, forced draft fans, and condensate pumps operate at their performance limits, significantly increasing the probability of protection shutdowns. As an energy-saving component, the variable frequency drive (VFD) is susceptible to failure when switching between power frequency and variable frequency modes, during turbine start-up and shutdown, and during protection actions.

[0004] In current technology, after the main fuel trip (MFT) of a thermal power unit, the protection to shut down the two primary air fans is designed with a hard-wired circuit. This circuit runs from the MFT relay cabinet to the sequential control cabinet, and is connected in parallel with the primary air fan trip command to the local equipment, achieving a hard-circuit trip of the primary air fans. Primary air fan operation is divided into two modes: power frequency and variable frequency. Because a certain thermal power unit's primary air fan has been operating in variable frequency mode for a long time, the protection device is designed with an MFT trip hard-wired circuit connected in parallel to the primary air fan inverter trip command. After the MFT trips, the primary air fan can be normally protected and shut down in variable frequency mode, but in power frequency mode, the primary air fan main protection fails to trip. The inability to shut down the primary air fan can easily cause overpressure in the boiler system, posing a significant safety hazard. Summary of the Invention

[0005] This application provides a method and system for eliminating the failure of primary air fan protection control device in thermal power units. It is used to solve the technical problem of how to ensure the reliability of the protection logic device and prevent the main auxiliary machine protection from malfunctioning and failing to operate. It enables the primary air fan to stop normally in both variable frequency and power frequency modes, achieves independent protection action in variable frequency and power frequency modes, effectively eliminates the risk of primary air fan protection failure to operate, and avoids serious hidden dangers such as boiler overpressure.

[0006] In view of the above problems, this application provides a control device and method for eliminating the failure of primary air fan protection in thermal power units.

[0007] In a first aspect, embodiments of this application provide a control device for eliminating the failure of primary air turbine protection in thermal power units. The device includes: a basic motor drive stage; a primary air turbine protection shutdown condition SPPRO module, which is connected to the left digital input port of the basic motor drive stage; and a shutdown command module, which is connected to the right STOP port of the basic motor drive stage and receives trigger signals from the primary air turbine protection shutdown condition SPPRO module through the basic motor drive stage port. The shutdown command module includes a frequency converter stop port, a 6KV switch trip port, a frequency converter mode output port connected to the frequency converter stop port, and a power frequency mode output port connected to the 6KV switch trip port. When the primary air turbine protection shutdown condition SPPRO module is triggered, a shutdown command is output through the shutdown command module. In frequency converter mode, the shutdown command is output to the frequency converter stop port; in power frequency mode, the shutdown command is output to the 6KV switch trip port, thereby achieving protection action.

[0008] Secondly, this application provides a method for eliminating the failure of primary air turbine protection to operate in a thermal power unit. The method includes: when the 6 kV low voltage protection or main fuel trip MFT is triggered, obtaining the primary air turbine operating mode; when the primary air turbine operating mode is in frequency conversion mode, connecting the shutdown command to the frequency conversion mode output port and outputting it to the frequency converter stop port, thereby achieving protection operation by stopping the frequency converter; when the primary air turbine operating mode is in power frequency mode, connecting the shutdown command to the 6 kV switch trip port and outputting it to the 6 kV switch trip port, thereby achieving protection operation by tripping the 6 kV switch.

[0009] One or more technical solutions provided in this application have at least the following technical effects or advantages:

[0010] This application provides a control device and method for eliminating the failure of primary air turbine protection in thermal power units. It establishes a primary air turbine protection shutdown condition SPPRO module by inputting a 6kV low voltage protection or main fuel trip (MFT) hard-wired circuit into the left side of the motor's basic drive stage. A shutdown command module is set up, connected to the right side STOP port of the motor's basic drive stage. This module receives trigger signals from the primary air turbine protection shutdown condition SPPRO module through the motor's basic drive stage port. The shutdown command module includes a frequency converter stop port and a 6kV switch trip port. Simultaneously, a frequency converter stop port is added to the left side of the motor's basic drive stage. The system has two output ports: one for variable frequency mode and one for power frequency mode. The STOP command is ANDed with both variable frequency and power frequency modes and output to the variable frequency drive stop port and the 6kV switch trip port, respectively. When the 6kV low voltage protection or main fuel trip MFT is triggered, the primary air fan operation mode is determined. When the primary air fan is operating in variable frequency mode, the stop command is connected to the variable frequency mode output port and output to the variable frequency drive stop port, thus achieving protection operation by stopping the variable frequency drive. When the primary air fan is operating in power frequency mode, the stop command is connected to the 6kV switch trip port and output to the 6kV switch trip port, thus achieving protection operation by tripping the 6kV switch. This system solves the technical problem of ensuring the reliability of the protection logic device and preventing maloperation and failure to operate of the main auxiliary equipment protection. It enables the primary air fan to stop normally in both variable frequency and power frequency modes, achieving independent protection action in variable frequency and power frequency modes, effectively eliminating the risk of primary air fan protection failure to operate, and avoiding serious hidden dangers such as boiler overpressure. Attached Figure Description

[0011] Figure 1 This application provides a structural schematic diagram of a control device for eliminating the failure of primary air fan protection in thermal power units;

[0012] Figure 2 A flowchart illustrating a method for eliminating the failure of primary air fan protection in thermal power units, as provided in this application;

[0013] Explanation of the attached diagram labels: Variable frequency mode D1, Power frequency mode D2, Program-controlled start of primary air fan D3, Program-controlled stop of primary air fan D4, 6KV low voltage protection D5, Primary air fan interlock stop D6, Primary air fan is running D7, Primary air fan is stopped D8, Variable frequency drive stopped D9, 6KV switch tripped D10. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] This application provides a control device and method for eliminating the failure of primary air fan protection in thermal power units. It addresses the technical problem of ensuring the reliability of the protection logic device and preventing the main auxiliary machine protection from malfunctioning or failing to operate. It enables the primary air fan to shut down normally in both variable frequency and power frequency modes, achieving independent protection actions in variable frequency and power frequency modes. This effectively eliminates the risk of primary air fan protection failure and avoids serious hidden dangers such as boiler overpressure.

[0016] Example 1

[0017] like Figure 1 As shown, this application provides a control device for eliminating the failure of primary air fan protection in thermal power units, the device comprising:

[0018] Basic drive stage of electric motor;

[0019] A primary fan protection shutdown condition SPPRO module is connected to the left digital input port of the basic drive stage of the motor.

[0020] Specifically, in existing technology, after the main fuel trip (MFT) of a thermal power unit, the protection to shut down the two primary air fans is designed with a hard-wired circuit. This circuit runs from the MFT relay cabinet to the sequential control cabinet, and is connected in parallel with the primary air fan trip command to the local equipment, thus achieving a hard-circuit trip of the primary air fans. Primary air fan operation can be either power frequency or variable frequency. Because a certain thermal power unit's primary air fan has been operating in variable frequency mode for a long time, the protection device is designed with an MFT trip hard-wired circuit connected in parallel to the primary air fan inverter trip command. After the MFT trips, the primary air fan can be normally protected and shut down in variable frequency mode, but in power frequency mode, the primary air fan main protection fails to trip. The inability to shut down the primary air fan can easily cause overpressure in the boiler system, posing a significant safety hazard.

[0021] In this embodiment of the application, a control device for eliminating the failure of primary air turbine protection in thermal power units is provided. The start-up and shutdown of the primary air turbine are completed by the basic drive stage of the motor. The basic drive stage of the motor is equipped with a primary air turbine protection shutdown condition SPPRO module. The digital input port on the left side of the basic drive stage of the motor is connected to the SPPRO port, which together constitute the primary air turbine protection shutdown condition SPPRO module.

[0022] Preferably, the primary fan protection shutdown condition SPPRO module includes: a 6 kV low voltage protection port; a primary fan interlock shutdown port, wherein the primary fan interlock shutdown port and the 6 kV low voltage protection port are connected to the left digital input port of the motor basic drive stage through a selection condition module.

[0023] Preferably, the primary air turbine interlock stop port includes a main fuel trip (MFT) hardwired circuit.

[0024] Preferably, the selection condition module uses the primary fan interlock stop port or the 6 kV low voltage protection port as the selection condition.

[0025] The above steps establish the conditions for primary wind turbine protection shutdown. When the 6 kV low voltage protection or main fuel trip MFT is triggered, subsequent operations are performed, providing a basis for the protection of the subsequent primary wind turbine.

[0026] The shutdown command module is connected to the right STOP port of the motor base drive stage and receives the trigger signal of the primary fan protection shutdown condition SPPRO module through the motor base drive stage port. The shutdown command module includes a frequency converter stop port and a 6KV switch trip port.

[0027] A frequency conversion mode output port, which is connected to the frequency converter stop port;

[0028] A power frequency output port is provided, which is connected to the 6KV switch port.

[0029] Preferably, the variable frequency output port and the power frequency output port are located on the basic drive stage of the motor.

[0030] Specifically, in this embodiment of the application, the device further includes a shutdown command module. The shutdown command module is connected to the STOP port on the right side of the motor basic drive stage. After the primary fan protection shutdown condition SPPRO module is triggered, the shutdown command is output from the STOP port on the right side of the motor basic drive stage. The STOP port on the right side of the motor basic drive stage is connected to the inverter stop port and the 6KV switch trip port. At the same time, a frequency conversion mode output port and a power frequency mode output port are added on the left side of the motor basic drive stage, and the STOP shutdown command is ANDed with the frequency conversion mode and the power frequency mode respectively and output to the frequency converter stop port and the 6KV switch trip port.

[0031] When the SPPRO module for the primary wind turbine protection shutdown condition is triggered, a shutdown command is output through the shutdown command module. In variable frequency mode, the shutdown command is output to the stop port of the frequency converter, and in power frequency mode, the shutdown command is output to the trip 6kV switch port. This ensures that after a 6kV low voltage or main fuel trip MFT is triggered, the primary wind turbine can be correctly shut down in both variable frequency and power frequency modes, eliminating the possibility of primary wind turbine protection failure to operate.

[0032] Furthermore, the basic drive stage of the electric motor includes a programmable input port, which is connected to a programmable start port for the primary fan and a programmable stop port for the primary fan.

[0033] Furthermore, the motor base drive stage also includes: an STTD output terminal, which is connected to the programmable start primary fan port and outputs a primary fan running command; and an STPD output terminal, which is connected to the programmable stop primary fan port and outputs a primary fan stopped command.

[0034] The device provided in this application only requires the laying of a small number of signal cables. It adds three input / output ports, namely "frequency conversion mode", "power frequency mode" and "trip 6KV switch", to the original drive stage. The existing thermal power unit control system hardware can meet the requirements, and the investment cost is low. In addition to primary air fans, the device of this invention can also be applied to similar high-power frequency conversion equipment such as forced draft fans, induced draft fans, and condensate pumps. It has a good effect on improving the reliability of the system and has strong promotional significance.

[0035] In summary, the control device for eliminating the failure of primary air fan protection in thermal power units provided in this application embodiment has the following technical effects:

[0036] 1. This application provides a control device for eliminating the failure of primary air turbine protection in thermal power units. It establishes a primary air turbine protection shutdown condition SPPRO module by inputting a 6kV low voltage protection or main fuel trip (MFT) hard-wired circuit into the digital input on the left side of the motor's basic drive stage. A shutdown command module is provided, connected to the right side STOP port of the motor's basic drive stage. The module receives the trigger signal from the primary air turbine protection shutdown condition SPPRO module through the STOP port of the motor's basic drive stage. The shutdown command module includes a frequency converter stop port and a trip 6kV... KV switch port; at the same time, frequency conversion mode output port and power frequency mode output port are added to the left side of the motor basic drive stage, and the STOP stop command is ANDed with frequency conversion mode and power frequency mode respectively and output to the frequency converter stop port and the 6KV switch port; this solves the technical problem of how to ensure the reliability of the protection logic device and prevent the main auxiliary machine protection from malfunctioning and failing to operate, and realizes that the primary air fan can be stopped normally in both frequency conversion mode and power frequency mode, achieving independent protection action in frequency conversion mode and power frequency mode, effectively eliminating the risk of primary air fan protection failure to operate, and avoiding serious hidden dangers such as boiler overpressure.

[0037] 2. The device provided in this application only requires the laying of a small number of signal cables and the addition of three input / output ports, namely "frequency conversion mode", "power frequency mode" and "trip 6KV switch", to the original drive stage. The existing thermal power unit control system hardware can meet the requirements, and the investment cost is low. In addition to the primary air fan, the device of this invention can also be applied to similar high-power frequency conversion equipment such as forced draft fan, induced draft fan, and condensate pump, which has a good effect on improving the reliability of the system and has strong promotional significance.

[0038] Example 2

[0039] like Figure 2 As shown, this application provides a method for eliminating the failure of primary air fan protection to operate in thermal power units, the method comprising:

[0040] S100: When the 6 kV low voltage protection or main fuel trip MFT is triggered, the primary wind turbine operation mode is obtained;

[0041] S200: When the primary air fan is operating in frequency conversion mode, a shutdown command is connected to the frequency conversion mode output port and output to the frequency converter stop port. The protection operation is achieved by stopping the frequency converter.

[0042] S300: When the primary air fan is operating in power frequency mode, the shutdown command is connected to the 6KV switch port and output to the 6KV switch port to realize the protection operation through the 6KV switch.

[0043] Specifically, when the 6kV low voltage protection or main fuel trip MFT in the SPPRO module is triggered, the right-side STOP port of the motor basic drive stage outputs a shutdown command to obtain the primary wind turbine operating mode. It then determines whether the primary wind turbine is operating in variable frequency mode or power frequency mode. When the primary wind turbine is operating in variable frequency mode, the shutdown command is connected to the variable frequency mode output port and output to the variable frequency drive stop port, thus achieving protection operation under variable frequency mode. When the primary wind turbine is operating in power frequency mode, the shutdown command is connected to the 6kV switch trip port and output to the 6kV switch trip port, thus achieving protection operation under power frequency mode.

[0044] The embodiments of this application employ independent protection actions using both variable frequency and power frequency methods, which can effectively eliminate the risk of primary fan protection failure and avoid serious hidden dangers such as boiler overpressure.

[0045] Those skilled in the art will be able to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control device for eliminating the failure of primary air fan protection in thermal power units, characterized in that, The device includes: Basic drive stage of electric motor; A primary fan protection shutdown condition SPPRO module is connected to the left digital input port of the basic drive stage of the motor. The shutdown command module is connected to the right-side STOP port of the motor basic drive stage and receives the trigger signal of the primary fan protection shutdown condition SPPRO module through the motor basic drive stage port. The shutdown command module includes a frequency converter stop port and a 6KV switch trip port. A frequency conversion mode output port, which is connected to the frequency converter stop port; A power frequency output port is provided, which is connected to the 6KV switch port. When the primary wind turbine protection shutdown condition SPPRO module is triggered, a shutdown command is output through the shutdown command module. In frequency conversion mode, the shutdown command is output to the frequency converter stop port, and in power frequency mode, the shutdown command is output to the trip 6KV switch port to realize the protection action. The primary air turbine protection shutdown condition SPPRO module includes: 6KV undervoltage protection port; The primary fan interlock stop port and the 6KV low voltage protection port are connected to the left digital input port of the motor basic drive stage through the selection condition module; The primary wind turbine interlocking stop port includes the main fuel trip (MFT) hard-wired circuit.

2. The apparatus as claimed in claim 1, characterized in that, The variable frequency output port and the power frequency output port are located on the basic drive stage of the motor.

3. The apparatus as described in claim 1, characterized in that, The basic drive stage of the electric motor includes a programmable input port, which is connected to a programmable start port for the primary fan and a programmable stop port for the primary fan.

4. The apparatus as described in claim 3, characterized in that, The basic drive stage of the electric motor also includes: The STTD output terminal is connected to the programmable start primary air fan port and outputs a primary air fan running command. The STPD output terminal is connected to the programmable stop primary fan port and outputs a primary fan stop command.

5. The apparatus as claimed in claim 1, characterized in that, The selection criteria module uses either the primary fan interlock stop port or the 6KV low voltage protection port as the selection criteria.

6. A method for eliminating the failure of primary air fan protection to operate in thermal power units, characterized in that, The method is applied to the apparatus according to any one of claims 1-5, and the method includes: When the 6KV low voltage protection or main fuel trip MFT is triggered, the primary wind turbine operation mode is obtained; When the primary air fan is operating in frequency conversion mode, a shutdown command is connected to the frequency conversion mode output port and output to the frequency converter stop port. The protection operation is achieved by stopping the frequency converter. When the primary air turbine is operating in power frequency mode, the shutdown command is connected to the 6KV switch port and output to the 6KV switch port to realize the protection operation through the 6KV switch.

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