CN111490538A - Accident switching method suitable for primary air fan frequency conversion/power frequency switching system - Google Patents
Accident switching method suitable for primary air fan frequency conversion/power frequency switching system Download PDFInfo
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- CN111490538A CN111490538A CN202010328131.8A CN202010328131A CN111490538A CN 111490538 A CN111490538 A CN 111490538A CN 202010328131 A CN202010328131 A CN 202010328131A CN 111490538 A CN111490538 A CN 111490538A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/007—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources
Abstract
The invention discloses an accident switching method suitable for a primary fan frequency conversion/power frequency switching system, wherein the primary fan frequency conversion/power frequency switching system comprises a high-voltage frequency converter, a controller, a primary fan and the like; the accident switching method comprises the following steps: when the primary air fan operates in a variable frequency mode, the second circuit breaker and the third circuit breaker are closed, and the first circuit breaker is opened; when the high-voltage frequency converter fails, the second circuit breaker and the third circuit breaker are immediately disconnected, and the first voltage transformer and the second voltage transformer respectively disconnect the power frequency voltage phase theta of the busNAnd primary fan end phase θGTransmitted to the controller if thetaN＝θGAnd when the controller sends a closing instruction to the first circuit breaker, the first circuit breaker is closed, and the primary air fan operates at power frequency. The invention solves the problem of primary fan tripping caused by frequency converter failure, and greatly improves the reliability and economy of the unit.
Description
Technical Field
The invention relates to an accident switching method suitable for a primary fan frequency conversion/power frequency switching system, which is suitable for rapidly switching to a power frequency power supply under the condition of a high-voltage frequency converter fault.
Background
The primary fan of the thermal power plant plays a vital role in the operation of the boiler and the generator set, and once the high-voltage frequency converter breaks down and causes the primary fan to trip, the stable operation of the boiler can be directly threatened. If the primary air fan frequency converter can be automatically and quickly switched to power frequency operation after failure, the load reduction logic of the boiler is not triggered, so that the generator set continuously and stably operates, and the reliability and the economy of the generator set can be greatly improved.
At present, when a primary air fan frequency converter breaks down, the switching mode of the accident that usually adopts is: direct handover and delayed handover. The direct switching means that the terminal voltage of the primary air fan is consistent with the voltage phase sequence of the power frequency bus power supply, and the primary air fan is directly switched to the power frequency power supply. The switching method does not require the frequency, amplitude and phase of the power frequency power supply voltage and the primary fan end voltage, so that large impact current can be caused, and the switching method is rarely used in actual engineering. The time-delay switching means that the primary fan is automatically switched to a power frequency power supply after being passively operated for 5s or 10 s. When the primary air fan is powered off, the voltage and the rotating speed of the primary air fan can be gradually attenuated, the voltage and the frequency of the primary air fan can be greatly reduced after 5s or 10s, and the primary air fan is switched to the power frequency at the moment, so that larger current impact cannot be caused. However, the output of the primary fan is seriously reduced, so that load shedding logic can be triggered, and the operation stability of the boiler is seriously influenced.
Disclosure of Invention
The invention aims to provide an accident switching method suitable for a primary air fan frequency conversion/power frequency switching system, which aims to solve the problem of primary air fan tripping caused by frequency converter failure and greatly improve the reliability and economy of a unit.
The invention is realized by adopting the following technical scheme:
an accident switching method suitable for a primary air fan frequency conversion/power frequency switching system, wherein the primary air fan frequency conversion/power frequency switching system comprises a high-voltage frequency converter, a controller and a primary air fan; the primary air fan is connected to a power frequency bus through a first circuit breaker and a first voltage transformer on one hand, and is connected to a high-voltage frequency converter through a second voltage transformer and a third circuit breaker on the other hand, and the high-voltage frequency converter is connected to the power frequency bus through a second circuit breaker; the controller is used for receiving a power frequency voltage signal detected by the first voltage transformer and a machine terminal voltage signal measured by the second voltage transformer and sending instructions to the first circuit breaker, the second circuit breaker and the third circuit breaker, and the controller is also connected with the high-voltage frequency converter to establish a communication relation;
the accident switching method comprises the following steps:
when the primary air fan operates in a variable frequency mode, the second circuit breaker and the third circuit breaker are closed, and the first circuit breaker is opened; when the high-voltage frequency converter fails, the second circuit breaker and the third circuit breaker are immediately disconnected, and the first voltage transformer and the second voltage transformer respectively disconnect the power frequency voltage phase theta of the busNAnd primary fan end phase θGTransmitted to the controller if thetaN＝θGAnd when the controller sends a closing instruction to the first circuit breaker, the first circuit breaker is closed, and the primary air fan operates at power frequency.
The invention has the further improvement that when the high-voltage frequency converter normally works, the primary fan can realize undisturbed switching between the variable-frequency power supply and the power-frequency power supply through the accident switching system.
The invention has the further improvement that the controller is used for judging whether the power frequency voltage and the terminal voltage are in the same phase, if the power frequency voltage and the terminal voltage are in the same phase, the circuit breaker of the power frequency power supply is closed, and the power supply of the high-voltage frequency converter is disconnected.
Compared with the prior art, the invention has at least the following beneficial technical effects:
1. the invention creates the rapid same-phase switching of the primary fan frequency converter of the thermal power generating unit in China under the accident, and realizes the function of rapidly switching from the variable-frequency power supply to the power-frequency power supply under the accident of the high-voltage frequency converter.
2. The invention realizes the quick switching under the failure of the primary fan frequency converter, avoids the triggering of the boiler load reduction logic caused by the tripping of the primary fan, ensures the continuous and stable operation of the generator set, and can greatly improve the reliability and the economical efficiency of the generator set.
3. The invention greatly reduces the impact current of the primary fan stator during accident switching, shortens the oscillation time of the primary fan and increases the operation stability of the primary fan and a boiler system.
In summary, the same phase switching is repeated under the condition of the fault of the high-voltage frequency converter, so that the primary fan can be quickly switched to the power frequency without causing large impact current after losing the power supply of the frequency converter. The same-phase switching refers to that when the high-voltage frequency converter breaks down and is disconnected, the voltage phase of the primary fan machine end is detected, and when the power frequency voltage phase is consistent with the voltage phase of the primary fan machine end, the same phase is switched to a power frequency power supply. After the high-voltage frequency converter breaks down, the primary fan can be quickly switched from the variable-frequency power supply to the power-frequency power supply by using the same-phase switching, and large impact current is not caused.
Drawings
FIG. 1 is a diagram of a primary air fan frequency conversion/power frequency switching system of the present invention;
FIG. 2 is a flow chart of the same phase switching according to the present invention;
FIG. 3 is a simulation waveform diagram of a stator current of a conventional direct-switching primary air blower;
fig. 4 is a waveform diagram of the same phase switching primary fan stator current simulation according to the present invention.
Description of reference numerals:
1. a power frequency bus; 2. a first circuit breaker; 3. a second circuit breaker; 4. a third circuit breaker; 5. a first voltage transformer; 6. a second voltage transformer; 7. a high voltage frequency converter; 8. a controller; 9. a primary air blower.
Detailed Description
The technical solution of the present invention is further described in detail by the accompanying drawings.
As shown in fig. 1, the accident switching method applicable to a primary fan frequency conversion/power frequency switching system provided by the present invention includes a primary fan 9, where the primary fan 9 is connected to a power frequency bus 1 through a first circuit breaker 2 and a first voltage transformer 5, and is connected to a high voltage inverter 7 through a second voltage transformer 6 and a third circuit breaker 4, and the high voltage inverter 7 is connected to the power frequency bus 1 through a second circuit breaker 3.
The primary air fan frequency conversion/power frequency switching system further comprises a controller 8, wherein the controller 8 receives a power frequency voltage signal detected by the first voltage transformer 5 and a primary air fan end signal measured by the second voltage transformer 6 and sends an instruction to the first circuit breaker 2, the second circuit breaker 3 and the third circuit breaker 4.
As shown in fig. 2, in the same-phase accident switching method, when the primary air fan 9 operates in a variable frequency mode, the second circuit breaker 3 and the third circuit breaker 4 are closed, and the first circuit breaker 2 is opened. When the high-voltage frequency converter 7 has a fault, the second circuit breaker 3 and the third circuit breaker 4 are immediately disconnected, and the first voltage transformer 5 and the second voltage transformer 6 respectively disconnect the power frequency voltage phase theta of the busNAnd primary fan end phase θGIs transmitted to the controller 8 if thetaN＝θGWhen it is, the controlThe device 8 sends a closing instruction to the first circuit breaker 2, the first circuit breaker 2 is closed, and the primary air fan 9 operates at power frequency.
In order to verify that the accident same-phase switching method of the primary fan high-voltage frequency converter is better in performance, a simulation model of the primary fan frequency conversion/power frequency switching system is built under Matlab/Simulink, and the parameters of the simulation model are as follows: prime mover parameters, feedback system parameters, load motor parameters.
TABLE 1 Prime mover parameters
Tab.1 Prime mover parameters
As shown in fig. 3, the simulation result of the direct switching mode of the primary air fan frequency conversion/power frequency system of the boiler is shown. The primary fan is powered by the high-voltage frequency converter to stably operate (5.5kV and 45HZ), the 2s high-voltage frequency converter is suddenly disconnected, and 2.1s high-voltage frequency converter is directly switched to a 6kV bus power frequency power supply. At the moment, the impulse current of the fan stator is very large and reaches 20 times of the rated current, and meanwhile, the motor oscillation time is about 1.5 s.
As shown in fig. 4, the simulation result of the in-phase switching manner of the primary air fan frequency conversion/power frequency system of the boiler is shown. The primary air fan is powered by a high-voltage frequency converter to stably operate (5.5kV and 45HZ), the 2s frequency converter is suddenly disconnected in fault, and 2.1s is switched to a 6kV bus power frequency power supply in the same phase. Compared with direct switching, the same-phase switching of the stator impact current of the primary fan is greatly reduced, and the operation requirement is met, so that the influence of the tripping of the primary fan on the stability of the system is avoided.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (3)
1. An accident switching method suitable for a primary air fan frequency conversion/power frequency switching system is characterized in that the primary air fan frequency conversion/power frequency switching system comprises a high-voltage frequency converter (7), a controller (8) and a primary air fan (9); the primary air fan (9) is connected to the power frequency bus (1) through a first circuit breaker (2) and a first voltage transformer (5) on one hand, and is connected to the high-voltage frequency converter (7) through a second voltage transformer (6) and a third circuit breaker (4) on the other hand, and the high-voltage frequency converter (7) is connected to the power frequency bus (1) through a second circuit breaker (3); the controller (8) is used for receiving a power frequency voltage signal detected by the first voltage transformer (5) and a terminal voltage signal measured by the second voltage transformer (6) and sending instructions to the first circuit breaker (2), the second circuit breaker (3) and the third circuit breaker (4), and the controller (8) is also connected with the high-voltage frequency converter (7) to establish a communication relation;
the accident switching method comprises the following steps:
when the primary air fan (9) operates in a variable frequency mode, the second circuit breaker (3) and the third circuit breaker (4) are closed, and the first circuit breaker (2) is opened; when the high-voltage frequency converter (7) breaks down, the second circuit breaker (3) and the third circuit breaker (4) are immediately disconnected, and the first voltage transformer (5) and the second voltage transformer (6) respectively disconnect the phase theta of the power frequency voltage of the busNAnd primary fan end phase θGIs transmitted to the controller (8) if thetaN＝θGWhen the power frequency control circuit is used, the controller (8) sends a closing instruction to the first circuit breaker (2), the first circuit breaker (2) is closed, and the primary air fan (9) operates at the power frequency.
2. The accident switching method applicable to the primary fan frequency conversion/power frequency switching system of claim 1, wherein when the high-voltage inverter normally works, the primary fan (9) can realize undisturbed switching between the variable frequency power supply and the power frequency power supply through the accident switching system.
3. The accident switching method applicable to the primary fan frequency conversion/power frequency switching system of claim 1, wherein the controller (8) is used for judging whether the power frequency voltage and the generator terminal voltage are in the same phase, and if the power frequency voltage and the generator terminal voltage are in the same phase, closing a circuit breaker of the power frequency power supply and disconnecting the high-voltage inverter power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010328131.8A CN111490538A (en) | 2020-04-23 | 2020-04-23 | Accident switching method suitable for primary air fan frequency conversion/power frequency switching system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010328131.8A CN111490538A (en) | 2020-04-23 | 2020-04-23 | Accident switching method suitable for primary air fan frequency conversion/power frequency switching system |
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| CN111490538A true CN111490538A (en) | 2020-08-04 |
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| CN202010328131.8A Pending CN111490538A (en) | 2020-04-23 | 2020-04-23 | Accident switching method suitable for primary air fan frequency conversion/power frequency switching system |
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Citations (5)
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| US20080174258A1 (en) * | 2007-01-22 | 2008-07-24 | Johnson Controls Technology Company | System and method to extend synchronous operation of an active converter in a variable speed drive |
| CN103051282A (en) * | 2012-08-23 | 2013-04-17 | 上海外高桥第二发电有限责任公司 | Variable-frequency and industrial frequency switching device and switching method of Variable-frequency and industrial frequency switching device |
| CN105490616A (en) * | 2016-01-11 | 2016-04-13 | 宁波中金石化有限公司 | Circuit structure for boiler blower capable of automatically switching to power frequency from variable frequency |
| CN108266398A (en) * | 2017-01-03 | 2018-07-10 | 新疆知信科技有限公司 | Stable operation method during primary air fan frequency conversion cut frequency |
| CN109510471A (en) * | 2017-09-15 | 2019-03-22 | 奥的斯电梯公司 | Frequency converter, bypass frequency conversion control system and its method for handover control |
-
2020
- 2020-04-23 CN CN202010328131.8A patent/CN111490538A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080174258A1 (en) * | 2007-01-22 | 2008-07-24 | Johnson Controls Technology Company | System and method to extend synchronous operation of an active converter in a variable speed drive |
| CN103051282A (en) * | 2012-08-23 | 2013-04-17 | 上海外高桥第二发电有限责任公司 | Variable-frequency and industrial frequency switching device and switching method of Variable-frequency and industrial frequency switching device |
| CN105490616A (en) * | 2016-01-11 | 2016-04-13 | 宁波中金石化有限公司 | Circuit structure for boiler blower capable of automatically switching to power frequency from variable frequency |
| CN108266398A (en) * | 2017-01-03 | 2018-07-10 | 新疆知信科技有限公司 | Stable operation method during primary air fan frequency conversion cut frequency |
| CN109510471A (en) * | 2017-09-15 | 2019-03-22 | 奥的斯电梯公司 | Frequency converter, bypass frequency conversion control system and its method for handover control |
Non-Patent Citations (1)
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| 余瑞锋等: "高压变频技术在电厂锅炉引风机节能控制中的应用", 《低碳陕西学术研讨会论文集》 * |
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