CN109581219B - Fault detection method for excitation system of brushless alternating-current generator - Google Patents
Fault detection method for excitation system of brushless alternating-current generator Download PDFInfo
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- CN109581219B CN109581219B CN201811535547.6A CN201811535547A CN109581219B CN 109581219 B CN109581219 B CN 109581219B CN 201811535547 A CN201811535547 A CN 201811535547A CN 109581219 B CN109581219 B CN 109581219B
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Abstract
The invention discloses a fault detection method for an excitation system of a brushless alternating-current generator, which is applied to the brushless alternating-current generator and comprises the following steps: step 1, a voltage regulating device extracts a composite waveform generated by three-phase harmonic current induction of an excitation loop; step 2, performing fast Fourier transform on the extracted harmonic current composite waveform, decomposing the harmonic current composite waveform into 3 harmonic current phasors, and enabling included angles among the 3 phasors to be 120 degrees; and 3, adding the three decomposed phasors, and judging whether the excitation system of the alternating-current generator works normally or not if the result is equal to 0. The invention utilizes the generator voltage regulating device to realize the on-line detection function of the generator excitation system fault, can finish the fault judgment of the excitation generator and the rectifier without adding any auxiliary monitoring instrument, and improves the reliability of the use of the generator.
Description
Technical Field
The invention relates to the field of brushless excitation alternating-current generators, and realizes online measurement of the state of an excitation system of a brushless alternating-current generator.
Background
1. The early alternators were brush-excited alternators, in which the dc power for generating the generator field was obtained through slip rings mounted on a rotating shaft coaxial to the generator and fixed brushes. The direct current power supply on the fixed electric brush is generally self-excited or separately excited and controlled by a voltage regulating control unit, and the voltage regulating control unit directly controls an excitation winding of the alternating current generator to generate a magnetic field. The excitation system of the brushed excitation alternator does not involve an excitation generator and a rectifier.
2. Later, a brushless excitation alternating current generator which is novel in structure and excellent in performance was invented. It actually designs two generators, one of which is used as an excitation generator and the other is used as a generator. The armature winding of the excitation generator, the rectifier and the excitation winding of the generator are all arranged on a coaxial rotor of the generator, and no slip ring or brush contact is needed between the armature winding and the rectifier and the excitation winding of the generator. The excitation generator power is derived from the magnetic field generated by the excitation circuit fixed to the generator. The control of the output voltage of the generator can be easily achieved by only inputting a small direct current signal to the excitation loop. However, because the armature winding of the excitation generator is in a high-speed rotation state, turn-to-turn short circuit, inter-phase short circuit and inter-phase open circuit are very likely to occur due to overload or aging. Also, the rectifier rotating at high speed is subject to a large centrifugal force, and operates in a high temperature and vibration environment, and is subject to overvoltage, overcurrent, and other conditions, and the rectifier diode is likely to be damaged. Therefore, the excitation system fault of the brushless generator is mainly reflected in the faults of the magnetic excitation generator and the rectifier, and once the faults of the magnetic excitation generator and the rectifier fail to be processed in time, the generator cannot work normally, and even the excitation generator, an excitation loop, an excitation winding and the like are burnt.
3. Since the armature winding and the rectifier of the field generator are both mounted on the rotor of the generator and do not have any electrical contact with the outside, and usually, in order to detect whether the armature winding and the rectifier have a fault, they need to be detached from the rotor for detection, which is very inconvenient, so people want to use various methods to measure the faults of the field generator and the rectifier, including various fault diagnosis proposals: for example, the test process is complex and consumes much by comparing the curve change of the load current and the exciting current of the generator; in addition, the harmonic control and measurement module mentioned in the domestic patent (patent number: 201310282483.4) is used for detecting the frequency change of the harmonic signal component to judge the fault state of the rotary rectifier, although the fault of the rectifier can be judged under the condition that the rectifier is broken by a diode, the frequency change of the harmonic signal caused by the fault of an armature winding of an excitation generator is not considered, so that the frequency change of the harmonic signal component cannot be used for judging the uniqueness of the fault of the rotary rectifier, and a special harmonic control and measurement module and a harmonic analyzer need to be provided, so that the structure is complex and the cost is high.
Disclosure of Invention
The invention aims to overcome the defects of the prior art at present and is realized by the following technical scheme:
A fault detection method for an excitation system of a brushless alternating-current generator is characterized in that the excitation system of the brushless alternating-current generator comprises an excitation coil, an excitation generator on a generator rotor, a rectifier and an excitation winding.
Preferably, the detection method comprises:
and 3, adding the three decomposed phasors, and judging whether the excitation system of the alternating-current generator works normally or not if the result is equal to 0.
Preferably, the voltage regulator in step 1 is a digital voltage regulator based on a microprocessor, and is a voltage regulator that controls the exciting current of the exciting circuit to make the alternator output a stable voltage, and extracts a complex waveform induced by the three-phase harmonic current of the exciting circuit through the overcurrent detection circuit.
Preferably, in the step 1, the excitation loop formed by connecting the excitation coil and the voltage regulator induces a composite waveform generated by three-phase harmonic current.
Preferably, in step 2, a microprocessor inside the voltage regulating device performs fast fourier transform on the extracted harmonic current composite waveform, and decomposes the harmonic current composite waveform into 3 harmonic current phasors, and the included angles between the 3 phasors are 120 degrees.
Preferably, whether the sum of the decomposed 3 harmonic current phasors is equal to 0 or not is judged, if yes, the excitation system is judged to work normally, and if not, the excitation system is judged to be in fault.
The invention utilizes the voltage regulating device to realize the on-line detection function of the generator excitation system fault, can finish the fault judgment of the excitation generator and the rectifier without adding any auxiliary monitoring instrument, improves the reliability of the use of the generator, and has the advantages of simple method, low cost and easy realization.
Drawings
FIG. 1 is a flow chart of a method embodying the present invention;
FIG. 2 is a schematic diagram of a method of carrying out the present invention;
FIG. 3 is a phasor diagram of an exploded three phase current harmonic;
in fig. 2: the device comprises a 1-voltage adjusting device, a 2-brushless alternating current generator, a 104-freewheeling diode, a 105-IGBT power amplifying tube, a 106-overcurrent detection circuit, a 111-microprocessor, a 212-excitation coil, a 213-excitation circuit, a 214-excitation generator, a 215-rectifier, a 216-excitation winding, a 217-excitation generator armature winding, a 218-generator rotor, a 3-power connecting wire and a 22-stator winding.
Detailed Description
1. The method for detecting the excitation system fault of the brushless alternating-current generator on line according to the present invention is further described in detail with reference to the accompanying drawings:
2. a fault detection method for an excitation system of a brushless alternating-current generator comprises the following steps:
step 1: the voltage regulating device extracts a composite waveform generated by three-phase harmonic current induction of the excitation loop;
and 3, adding the three decomposed phasors, and judging whether the excitation system works normally or not if the result is equal to 0.
3. The excitation system of the alternating current generator comprises an excitation coil 212 and an excitation generator 214, a rectifier 215 and an excitation winding 216 on a generator rotor 218, a voltage regulating device 1 is connected with the excitation coil 212 to form an excitation loop 213, a direct current signal is input into the excitation loop 213 by the voltage regulating device 1, when the rotor 218 rotates and works, a three-phase alternating current source generated by the excitation generator 217 is converted into direct current through a three-phase bridge rectifier 215 and is output to the excitation winding 216, and a rotating magnetic field generated by the excitation winding 216 is induced by a stator winding 22 to generate three-phase alternating current output electric energy.
4. Since the load of the field generator 214 is a three-phase bridge rectifier structure loop, the load current of the rectifier 215 will generate three-phase symmetrical harmonic current components in the field generator armature winding 217 of the field generator 214, and 1 harmonic current complex waveform is generated in the field loop 212 through space induction.
5. An excitation over-current detection circuit 106 is arranged in the voltage regulating device 1, the microprocessor 111 extracts a harmonic current composite waveform induced by the excitation circuit 212 through the excitation over-current detection circuit 106, and performs fast fourier transform on the harmonic current composite waveform to decompose the harmonic current composite waveform into 3 harmonic current phasors, the included angles among the 3 phasors are 120 degrees, a phasor diagram is shown in fig. 3, and the 3 harmonic current phasors are respectively expressed as Ia ═ 0 ° -A, Ib ═ Ib ═ 120 ° -A, Ic ═ Ic ═ 240 ° a. Wherein Ia, Ib and Ib are effective values of 3 harmonic current phasors respectively. Since the load of the excitation generator 214 is a three-phase bridge rectification structure loop, when the excitation system works normally, the load of the excitation generator 214 is a three-phase symmetric load, so the effective values of the three-phase harmonic current components generated by the armature winding 217 of the excitation generator 214 are also equal, and it is further demonstrated that the effective values of the decomposed 3 harmonic current phasors are also equal, that is, Ia Ib Ic, the three phasors are added, Ia + Ib + Ic is 0; when the armature winding 217 of the excitation generator has inter-turn short circuit, inter-phase open circuit or rectifier diode breakdown and open circuit fault of the rectifier current 215, the load of the excitation generator 214 is no longer three-phase symmetrical load, the effective values of three-phase harmonic current components generated at the armature winding 217 of the excitation generator 214 are also unequal, and it is further argued that the effective values of the decomposed 3 harmonic current phasors are also no longer equal, that is, Ia is not equal to Ib is not equal to Ic, the three phasors are added, and Ia + Ib + Ic is not equal to 0.
6. And if the sum of the three phasors is equal to 0, judging that the excitation system works normally if the sum of the three phasors is equal to 0, and otherwise, judging that the excitation system fails.
7. When the excitation system fails, the voltage regulating device sends out an alarm signal or automatically turns off the excitation output according to the requirement, so that the generator stops working.
While there have been shown and described what are at present considered the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (4)
1. A brushless AC generator excitation system fault detection method, the brushless AC generator excitation system includes excitation generator, rectifier and excitation winding on excitation coil and generator rotor, excitation coil and voltage regulation device connect and form the excitation loop, the voltage regulation device is equipped with the excitation and overflows detection loop and microprocessor inside, characterized by that: the detection method comprises the following steps:
step 1, a voltage regulating device extracts a composite waveform generated by three-phase harmonic current induction of an excitation loop;
step 2, performing fast Fourier transform on the composite waveform generated by the induction of the extracted three-phase harmonic current, decomposing the composite waveform into 3 harmonic current phasors, and enabling included angles among the 3 phasors to be 120 degrees;
and 3, adding the three decomposed phasors, and judging whether the excitation system of the alternating-current generator works normally according to whether the result is equal to 0.
2. A method of detecting a fault in a brushless alternator field system as in claim 1 wherein: the voltage regulating device in the step 1 is a digital voltage regulator based on a microprocessor, is a voltage regulating device for controlling the exciting current of the exciting circuit to enable the alternating current generator to output stable voltage, and extracts a composite waveform generated by three-phase harmonic current induction of the exciting circuit through the overcurrent detection circuit.
3. A method of detecting a fault in a brushless alternator field system as in claim 2 wherein: in the step 2, a microprocessor in the voltage regulating device performs fast Fourier transform on the extracted composite waveform generated by three-phase harmonic current induction, the composite waveform is decomposed into 3 harmonic current phasors, and the included angles between the 3 phasors are 120 degrees.
4. A method of detecting a fault in a brushless alternator field system according to claim 3 wherein: and judging whether the sum of the 3 decomposed harmonic current phasors is equal to 0, if so, judging that the excitation system normally works, and if not, judging that the excitation system has a fault.
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| CN112986816B (en) * | 2019-12-12 | 2022-03-29 | 南京南瑞继保电气有限公司 | Brushless exciter armature side fault online detection device and method |
| CN111308345B (en) * | 2020-04-08 | 2021-10-22 | 清华大学 | Method and system for detecting electrical fault of brushless exciter and storage medium |
| CN111308346B (en) * | 2020-04-08 | 2021-05-11 | 清华大学 | Method and system for detecting a fault in a field winding of a stator of a polyphase brushless exciter |
| CN111650509B (en) * | 2020-05-12 | 2022-10-14 | 浙江浙能电力股份有限公司台州发电厂 | Fault judgment method and device for brushless excitation motor, computer equipment and medium |
| CN111650510B (en) * | 2020-05-12 | 2022-10-18 | 浙江浙能电力股份有限公司台州发电厂 | Fault judgment method and device for brushless excitation motor, computer equipment and medium |
| CN111983419B (en) * | 2020-08-31 | 2023-06-23 | 清华大学 | Method and system for detecting diode faults in a multiphase brushless exciter rectifier |
| CN117872009B (en) * | 2024-01-11 | 2024-06-18 | 北京科电亿恒电力技术有限公司 | Monitoring method, system, equipment and storage medium of excitation rectifying equipment |
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