CN109444509B - Device for measuring bearing current of wind driven generator and application thereof - Google Patents
Device for measuring bearing current of wind driven generator and application thereof Download PDFInfo
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- CN109444509B CN109444509B CN201811302896.3A CN201811302896A CN109444509B CN 109444509 B CN109444509 B CN 109444509B CN 201811302896 A CN201811302896 A CN 201811302896A CN 109444509 B CN109444509 B CN 109444509B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/08—Measuring current density
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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Abstract
The invention discloses a device for measuring bearing current of a wind driven generator and application thereof, and the device comprises a generator, a PWM converter, an encoder, a gear box and an oscilloscope, wherein a stator of the generator is connected with the machine side of the PWM converter through a first cable, a rotor of the generator is connected with the gear box through a coupler, two ends of the rotor are provided with grounding electric brushes, one end of the oscilloscope is connected with the grounding electric brush, the other end of the oscilloscope is connected to a shell of the generator and is grounded, the encoder is arranged at the non-driving end of the generator, the encoder is connected with the PWM converter through a second cable, shaft voltage U is obtained by using the oscilloscope, and then the bearing current is obtained by calculation according to a formula.
Description
Technical Field
The invention relates to the technical field of wind driven generators, in particular to a bearing current measuring device of a wind driven generator and application thereof.
Background
The generator is a core component of the wind generating set, the operation reliability of the generator directly influences the stability of the generator, according to the generator fault statistics of a certain MW type, the bearing fault is a main factor influencing the operation of the generator, and the bearing electrical erosion incidence is high.
The causes of the shaft voltage generation can be broadly divided into two categories: motor self factors and converter factors. The shaft voltage generated by the motor has three main aspects: the axis voltage generated by magnetic flux asymmetry, the axis voltage generated by residual magnetism (permanent magnet motor), and the axis voltage generated by static charge. The current transformer is mainly the shaft voltage due to the common mode voltage. After the high-frequency part of the frequency converter enters the generator, charging and discharging are carried out on a distributed capacitor insulated by a generator bearing and a bearing, so that shaft voltage and shaft current are caused; in addition, when the frequency converter works normally, common mode voltage and differential mode voltage can be generated, so that shaft voltage and shaft current are formed on a generator rotor through induction. Most of the shaft current is conducted to the ground through the machine shell and the grounding carbon brush, but part of the current can flow through the bearing after insulation failure or oil film breakdown, and the bearing current can damage the bearing. The bearing electric erosion mainly occurs because when the shaft voltage (bearing current) exceeds the threshold voltage of the bearing oil film, the oil film (about 0.005mm) between the inner ring, the outer ring and the rolling element of the bearing is continuously charged and discharged, the oil film is broken down to form spark discharge, and obvious washboard lines can be seen on the outer surface of the inner ring and the inner surface of the outer ring of the bearing, so that the early failure of the bearing is caused.
Since the bearing current cannot be directly measured, the existing standards do not specify the measurement standards and methods for the bearing current, nor do they specify a calculation method. The national standard GBT 1029-2005 three-phase synchronous motor test method provides for measuring shaft voltage, and the tested motor is operated under the condition of rated voltage and rated rotating speed to measure the shaft voltage in no-load operation. Part 1 of the national standard GBT 23479.1-2009 doubly-fed asynchronous generator of a wind generating set: technical Condition requires the shaft voltage to be less than 0.5V. IEC60034-17Cage index motors where fed from converters only indicate that no protection is required when the shaft voltage (peak) is less than 500mV and that protection devices are added when the shaft voltage (peak) is more than 500 mV. 8.2.7(2) in GL guiding line 2010 requires that the current density flowing through the bearing be less than 0.1A/mm2, but there is still no measurement or calculation of the bearing current.
Through retrieval, the technologies related to the scheme have two types: 1. CN 200980127705-method and apparatus for measuring bearing current in an electric machine; 2. CN 201080065139-bearing current sensor device with energy converter. Patent No. CN200980127705 proposes an apparatus and method for measuring bearing current in a motor, mainly using an antenna installed near the bearing to detect the radio frequency signal during discharging, and transmitting the signal to an oscilloscope, integrating or counting the collected radio frequency signal, thereby calculating the bearing current; patent No. CN201080065139 proposes a sensor device which is mounted beside or on a shaft and converts mechanical energy into electrical energy, and transmits the electrical energy to a detection device by means of wireless transmission. The two inventions describe the shaft current detection and evaluation device, and the device is most different from the invention in that a detailed calculation method of the bearing current is not involved.
Disclosure of Invention
The invention aims to provide a device for measuring bearing current of a wind driven generator and application thereof, and solves the technical problem that the bearing current cannot be accurately and normatively calculated and measured in the prior art.
The utility model provides a measuring device of aerogenerator bearing current, includes generator, PWM converter, encoder, gear box and oscilloscope, the stator of generator with the machine side of PWM converter passes through first cable junction, the rotor of generator with the gear box passes through the coupling joint, and installs the ground connection brush at the rotor both ends, oscilloscope one end with the ground connection brush is connected, and the other end connects to generator casing and ground connection, the encoder is installed the non-drive end of generator, and the encoder with the PWM converter passes through the second cable junction.
On the basis of the technical scheme, the invention can be further improved as follows:
furthermore, the coupler is an insulating coupler, and the beneficial effect of the step is that the gear box can be effectively protected from erosion by the coupler device with insulating capacity.
Furthermore, the switching frequency of the PWM converter is 2KHz or 3KHz, the wave sending mode of the PWM converter is one of 3-section wave sending, 5-section wave sending and 7-section wave sending, and the beneficial effect of the step is that the subsequent detection of the shaft voltage is facilitated.
Further, the generator is a doubly-fed generator.
Further, the generator is a synchronous motor.
Furthermore, the measuring device further comprises an RC filter, the RC filter is communicated with the first cable through a three-phase cable, and the beneficial effect of the step is that signal interference can be reduced by using the filter.
The invention also discloses an application of the device, namely the device is adopted to measure and calculate the bearing current or the bearing current density, and the specific method is as follows: the shaft voltage U under different working conditions is measured by using an oscilloscope, and the bearing current or the bearing current density is calculated according to the following formula
Wherein, the shaft voltage U under different working conditions refers to: and adjusting the switching frequency of the PWM converter, the wave sending mode of the PWM converter and the parameters of the RC filter, and displaying the voltage U by the oscilloscope.
The invention has the beneficial effects that:
1. the invention provides a device for measuring bearing current of a wind driven generator and application thereof, when a bearing electric corrosion problem occurs in the running process of generators of 2MW and 5MW units, the method is adopted to measure shaft voltage and calculate bearing current, and measures for inhibiting the bearing current are determined; the generator design initial stage of 3MW unit adopts this scheme to carry out bearing insulating material preliminary election, measures through this scheme after the motor design is accomplished and verifies, optimizes bearing insulation structure, has confirmed effectual bearing current suppression measure.
2. The invention solves the problem that the prior art can not calculate and measure the bearing current in a standard and standard way;
3. the invention can solve the problem of preselection of the bearing insulating material in the initial design stage;
4. the invention solves the problem of unreasonable selection of bearing insulating materials, optimizes the bearing insulating structure, effectively inhibits the bearing current and protects the bearing from electric corrosion;
5. the invention can determine the effective measure of the bearing current, solve the problem of the bearing electric corrosion fault of the wind driven generator, reduce the bearing fault rate and improve the availability of the whole machine.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic view of a bearing current measuring device for a wind turbine according to embodiment 1 of the present invention;
FIG. 2 is a schematic view of a bearing current measuring device for a wind turbine according to embodiment 2 of the present invention;
reference numerals:
1-a doubly-fed generator; 2-PWM converter; 3-an encoder; 4-a gearbox; 5-an oscilloscope; 6-a stator; 7-a rotor; 8-a grounding brush; 9-a first cable; 10-a second cable; 11-synchronous machine, 12-RC filter; 13-a three-phase cable; 14-coupling.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.
It is to be noted that, unless otherwise specified, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which the invention pertains.
In the description of the present application, it is to be understood that the terms "center", "upper", "lower", "vertical", "horizontal", "top", "bottom", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Example 1
The embodiment discloses a device for measuring the bearing current of a wind driven generator, which comprises a doubly-fed generator 1, a PWM converter 2, an encoder 3, a gear box 4 and an oscilloscope 5, wherein a stator 6 of the doubly-fed generator is connected with the machine side of the PWM converter 2 through a first cable 9, and the grid side of the PWM converter 2 is connected to a power grid;
the rotor 7 of the doubly-fed generator 1 is connected with the gear box 4 through the coupler 14, the two ends of the rotor 7 are provided with the grounding brushes 8, the coupler 14 in the double-fed generator is a coupler device with insulating capacity, the gear box can be effectively protected from being damaged by electric corrosion, and the grounding brushes 8 adopt inlet grounding carbon brushes with high wear resistance and high conductivity and taking electrographite as a base material, and when the grounding brushes are connected with the rotor, arc-shaped surfaces are in contact with the inlet grounding carbon brushes.
One end of the oscilloscope 5 is connected with the grounding electric brush 8, the other end of the oscilloscope is connected to the doubly-fed generator 1 and grounded, the encoder 3 is installed at the non-driving end of the doubly-fed generator 1, the encoder 3 is connected with the PWM converter 2 through a second cable 10, the second cable 10 is a cable with a shielding layer and provided with a signal identification mark, and the oscilloscope can obtain the shaft voltage U under different working conditions.
The embodiment also discloses an application of the device, namely the device is used for measuring and calculating the shaftThe current bearing or the current density of the bearing is specifically as follows: the shaft voltage U under different working conditions is measured by using an oscilloscope, and the bearing current or the bearing current density is calculated according to the following formula
Wherein, the shaft voltage U under different working conditions refers to: and after the switching frequency of the PWM converter and the wave-sending mode of the PWM converter are adjusted, the voltage U is displayed by the oscilloscope, the switching frequency of the PWM converter is 2KHz or 3KHz, and the wave-sending mode of the PWM converter is one of 3-band wave-sending mode, 5-band wave-sending mode and 7-band wave-sending mode.
Example 2:
the embodiment discloses a wind power generator bearing current measuring device, which comprises a synchronous motor 11, a PWM converter 2, an encoder 3, a gear box 4 and an oscilloscope 5, wherein a stator 6 of the synchronous motor 11 is connected with the machine side of the PWM converter 2 through a first cable 9, the grid side of the PWM converter 2 is connected with a power grid, and the difference from the embodiment 1 is that the first cable 9 has two parts which are respectively connected with different stators;
the rotor 7 of the synchronous motor 11 is connected with the gear box 4 through a coupler 14, and two ends of the rotor 7 are provided with grounding brushes 8, the coupler in the invention is a coupler 14 device with insulating capability, so that the gear box can be effectively protected from being damaged by electric corrosion, and the grounding brushes 8 adopt inlet grounding carbon brushes with high wear resistance, high conductivity and electrochemical graphite as a base material, and are in contact with arc surfaces when being connected with the rotor.
One end of the oscilloscope 5 is connected with the grounding electric brush 8, the other end of the oscilloscope is connected to the synchronous motor 11 and grounded, the encoder 3 is installed at the non-driving end of the synchronous motor 11, the encoder 3 is connected with the PWM converter 2 through a second cable 10, the second cable 10 is a cable with a shielding layer and provided with a signal identification mark, and the oscilloscope can obtain the shaft voltage U under different working conditions.
The present embodiment further includes an RC filter 12, wherein the RC filter 12 is communicated with the first cable 9 through a three-phase cable 13, and signal interference can be reduced by using the filter.
The embodiment also discloses an application of the device, namely the device is adopted to measure and calculate the bearing current or the bearing current density, and the specific method is as follows: the shaft voltage U under different working conditions is measured by using an oscilloscope, and the bearing current or the bearing current density is calculated according to the following formula
Wherein, the shaft voltage U under different working conditions refers to: after the switching frequency of the PWM converter, the wave sending mode of the PWM converter and the parameters of the RC filter are adjusted, the voltage U displayed by the oscilloscope is obtained, the switching frequency of the PWM converter is 2KHz or 3KHz, the wave sending mode of the PWM converter is one of 3-band wave sending, 5-band wave sending and 7-band wave sending, and the adjustment of the parameters of the RC filter refers to the adjustment of the sizes of a resistor and a capacitor. .
In the description of the present invention, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention, and they should be construed as being included in the following claims and description.
Claims (6)
1. A device for measuring bearing current of a wind driven generator is characterized by comprising a generator, a PWM converter, an encoder, a gear box and an oscilloscope, wherein a stator of the generator is connected with the machine side of the PWM converter through a first cable, a rotor of the generator is connected with the gear box through a coupler, two ends of the rotor are provided with grounding electric brushes, one end of the oscilloscope is connected with the grounding electric brush close to the gear box, the other end of the oscilloscope is connected to a generator shell and is grounded, the encoder is arranged at the non-driving end of the generator, and the encoder is connected with the PWM converter through a second cable;
the coupler is an insulating coupler;
the measuring device further includes an RC filter in communication with the first cable through a three-phase cable.
2. The wind turbine bearing current measuring device according to claim 1, wherein the switching frequency of the PWM converter is 2KHz or 3KHz, and the PWM converter is configured to emit one of 3-band emission, 5-band emission and 7-band emission.
3. A wind turbine bearing current measuring device according to claim 2, wherein said generator is a doubly fed generator.
4. A wind turbine bearing current measuring device according to claim 2, wherein the generator is a synchronous machine.
5. Use of a device for measuring the bearing current of a wind turbine according to any of claims 1 to 4, characterized in that the bearing current is calculated using the shaft voltage U measured by an oscilloscope under different operating conditions according to the following formula
6. Use of a device according to claim 5 for measuring bearing currents of wind turbines, wherein the shaft voltages U under different operating conditions are: and adjusting the switching frequency of the PWM converter, the wave sending mode of the PWM converter and the parameters of the RC filter, and displaying the voltage U by the oscilloscope.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811302896.3A CN109444509B (en) | 2018-11-02 | 2018-11-02 | Device for measuring bearing current of wind driven generator and application thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811302896.3A CN109444509B (en) | 2018-11-02 | 2018-11-02 | Device for measuring bearing current of wind driven generator and application thereof |
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| CN109444509A CN109444509A (en) | 2019-03-08 |
| CN109444509B true CN109444509B (en) | 2021-03-23 |
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| CN112751443A (en) * | 2019-10-31 | 2021-05-04 | 中车株洲电力机车研究所有限公司 | Motor shaft voltage test structure |
| CN113960470B (en) * | 2021-08-24 | 2022-07-15 | 北京金风慧能技术有限公司 | Method and device for detecting shaft current of generator |
| CN116007943A (en) * | 2023-01-16 | 2023-04-25 | 西安热工研究院有限公司 | Method and system for detecting electric corrosion fault of doubly-fed asynchronous wind generator bearing |
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| DE602006008423D1 (en) * | 2006-03-13 | 2009-09-24 | Skf Ab | Method and device for displaying electrical discharges in a bearing of an electric drive system |
| FI20080438A0 (en) * | 2008-07-15 | 2008-07-15 | Abb Oy | Method and apparatus for measuring bearing currents in an electric machine |
| DE102010002297A1 (en) * | 2010-02-24 | 2011-08-25 | Siemens Aktiengesellschaft, 80333 | Method and device for evaluating the damage to rolling bearings, in particular to converter-fed electrical machines |
| SE536334C2 (en) * | 2011-11-23 | 2013-08-27 | Skf Ab | Method and system for detecting currents through layer rotating systems |
| US9653970B2 (en) * | 2014-02-05 | 2017-05-16 | C-Motive Technologies Inc. | Rotary capacitor for shunting high frequency bearing currents and reducing EMI in electric machinery |
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Effective date of registration: 20211207 Address after: 226407 No.139 Mudanjiang Road, Rudong Economic Development Zone, Nantong City, Jiangsu Province Patentee after: JIANGSU HAIZHUANG WIND POWER EQUIPMENT CO.,LTD. Address before: 401122 No. 30 Jinyu Avenue, Jingkaiyuan, North New District of Chongqing Patentee before: CSIC HAIZHUANG WINDPOWER Co.,Ltd. |