JPS61244222A - Arm missing detector for rotary rectifier - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an arm defect detection device for a rotary rectifier that rectifies the output of an AC exciter to excite the main field of a main machine such as a brushless synchronous machine. In this type of rotary rectifier, if any arm of the rectifier circuit is damaged, the output will be reduced and the operation of the brushless synchronous machine etc. will be affected. It is important to be able to detect and take countermeasures.

[Prior art and its problems]

Generally, the power to excite the field of a brushless synchronous machine is obtained by rectifying the output of a three-phase AC exciter installed on the same rotating shaft as the main machine of the synchronous machine using a three-phase bridge rectifier circuit of the rotating alternator. be done. Therefore, if any arm in the three-phase bridge rectifier circuit of the rotary rectifier is damaged, the output of the rotary rectifier will be reduced, and the excitation voltage for the main field of the main engine will be reduced, which in extreme cases may cause the main engine to step out. become the cause. In order to prevent the above-mentioned inconvenient phenomenon, it is necessary to promptly detect arm damage of the rotary rectifier and take countermeasures. Since the rotary rectifier is rotating, it is impossible to directly measure the voltage or current of each arm of the rotary rectifier to detect the presence or absence of a defective arm. Therefore, in the past, the current on the stationary field side of the AC exciter was measured, and the measured value was checked against the field current reference value for each case depending on the operating state of the main engine to determine whether the measured value was a value that would normally be impossible. In the case shown, it is determined that the arm of the rotary rectifier is missing, or alternatively, the voltage waveform between the neutral point of the three-phase AC exciter and the ground is detected and the presence or absence of the arm of the rotary rectifier is estimated from that waveform. This method is being used.

However, in the former judgment method, there are many cases in which the classification is done according to the operating state of the main engine, and the field current reference values in these cases are similar to each other, so it is difficult to ensure accuracy in the comparison. It is difficult and there is a high possibility of misjudgment.
In addition, the latter method of estimating from the voltage waveform has the disadvantage of requiring slip rings, brushes, etc. to detect the waveform from the outside, and is particularly difficult to maintain when using a brushless synchronous machine. The disadvantage is that it loses its value.

[Purpose of the invention]

In view of the above-described drawbacks of conventional means for detecting arm defects in rotary rectifiers, the present invention provides a device that can easily and reliably detect arm defects in rectifying circuits in rotary rectifiers with an extremely simple configuration. The purpose is to

[Key points of the invention]

In order to achieve the above object, the present invention provides a pickup coil for the current of the field circuit of the AC exciter, a fundamental wave component or a specific harmonic component or a specific harmonic component of the induced voltage of the pickup coil. It consists of a filter that passes only each harmonic component below the harmonic, a comparator input through the filter, and a detection means activated by the output signal of the comparator, and detects when the input of the comparator exceeds a predetermined value. By activating the detection means based on the output signal of the comparator, the current waveform of the field circuit of the exciter when the arm of the rotary rectifier is broken is determined to be the same as when all arms of the rotary rectifier are normal. The arm defect is detected by utilizing the fact that the waveform of the current in the exciter field circuit and therefore the ratio of harmonic components contained in the skeleton current are different.

[Embodiments of the invention]

Next, the present invention will be explained in detail based on embodiments shown in the drawings.

As shown in FIG. 1, the main field 3 of the main machine 1 of a brushless alternator that is folded in a load, for example, the electric power system 2, is connected to a three-phase AC exciter 5 by a field 6 excited from an exciting electric TM7. The excitation current is supplied by rectifying the output through a rotary rectifier 4 consisting of a three-phase bridge rectifier circuit.

Generally, when an exciting current is supplied to the main field 3 of the main pole 1 through a three-phase bridge rectifier circuit of the rotary rectifier 4, the current waveform of the field 6 of the AC exciter 5 is different from that of each arm of the rotary rectifier 4. FIG. 3 shows one cycle when the signal is normal. When the current waveform is analyzed, it is known that the 6th harmonic component of the fundamental wave is extremely dominant, and the content ratio of each harmonic component below the 5th harmonic is low.

On the other hand, when any arm of the rotary rectifier 4 is missing, the current waveform of the field 6 for one period is as shown in FIG. 4, which is clearly different from that when each arm is normal. Different from current waveform. When analyzing the waveform of the field current in this case, not only does the proportion of each harmonic component below the 5th harmonic increase, but when all the arms of the rotary rectifier 4 are normal, the current of the field 6 is shown separately. It has also been experimentally confirmed that the fundamental wave component, which is hardly included in the above, is contained in almost the same proportion as the sixth harmonic component.

As a result of the above, as shown in FIG. 1, the field 6 of the three-phase AC exciter 5 supplies power to the main field 3 of the main machine 1 of the brushless synchronous machine via the rotary rectifier 4 forming a three-phase bridge rectifier circuit.
A pick-up coil 8 is provided in the coil 8, and a filter 10 that passes only the fundamental wave of the induced voltage of the coil 8, a specific harmonic component, or each harmonic component below the specific harmonic is input, and the output of the filter is inputted to generate an output signal. If a rotary rectifier arm defect detection device main body 9 is connected to the pickup coil 8, it is constructed by connecting a comparator 11 that transmits a signal and a detection means, such as a relay 12, which is activated by the output signal of the comparator 11 as shown in FIG. For example, by appropriately selecting the filter 10, arm loss in the rotary rectifier can be easily and reliably detected.

That is, as the filter 10, the pickup coil 8 provided in the field 6 of the AC exciter 5 passes only the voltage component induced by the fundamental wave component of the circuit current among the voltages induced by the circuit current of the field 6. By using a filter 10 that is either a bandpass filter or a low-pass filter that passes only voltage components induced by each harmonic component below the fifth harmonic of the circuit current, an arm defect can be caused in the rotary rectifier 4. In this case, the fundamental wave component or each harmonic component below the 5th harmonic of the current in the field circuit, which is dominant due to the above-mentioned reason, passes through the filter 10 and is input to the comparator 11, and the input value is When the value exceeds a predetermined value, the comparator 11 outputs a signal and the relay 12 is activated, thereby making it possible to reliably detect arm failure of the rotary rectifier 4.

〔Effect of the invention〕

As described above, the present invention provides an arm defect detection device for a rotary rectifier that rectifies the output of an AC exciter to excite the main field of a main machine such as a brushless synchronous machine, in which a current in a field circuit of the AC exciter is provided. a pickup coil for the pickup coil, a filter that passes only the fundamental wave of the induced voltage of the pickup coil, a specific harmonic component, or each harmonic below the specific harmonic, a comparator input through the filter, and an output signal of the comparator. The field located on the stationary side of the AC exciter is activated by the output signal of the comparator when the input of the comparator exceeds a predetermined value. Since the arm defect in the rotary rectifier is detected by picking up the value of the fundamental wave component, a specific harmonic component, or each harmonic component below a specific harmonic of the current flowing in the magnetic circuit, it is easy to detect. The configuration allows easy and reliable detection, and since no slip ring or brush is required for the detection device, maintenance is easy and a brushless effect can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the excitation circuit of the main engine by the AC exciter in which the rotary rectifier arm defect detection device of the present invention is arranged, and FIG. 2 is a conceptual diagram showing the detection circuit of the defect detection device of the present invention. Figures 3 and 4 are diagrams showing the waveforms of the field circuit current of a three-phase AC exciter when the entire arm of the rotating current vibrator is normal and when one of the arms is defective, respectively. . 1... Main engine, 3... Main field, 4... Rotating rectifier,
5... AC exciter, 6... Field of the AC exciter, 7.
... Excitation power supply, 8... Big up Koinope 9...
- Rotating rectifier arm defect detection device, 1o... filter, 11... comparator, 12... relay. 21st! f Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1) In an arm defect detection device for a rotary rectifier that rectifies the output of an AC exciter to excite the main field of a main machine such as a brushless synchronous machine, A pickup coil, a filter that passes only the fundamental wave component or a specific harmonic component of the induced voltage of the pickup coil, or each harmonic component below the specific harmonic, a comparator input through the filter, and an output of the comparator. It consists of a detection means activated by a signal,
An arm defect detection device for a rotary rectifier, characterized in that the detection means is activated by an output signal of the comparator when the input of the comparator exceeds a predetermined value. 2) An arm defect detection device for a rotary rectifier according to claim 1, wherein the filter is a bandpass filter that passes only the fundamental wave component of the voltage of the pickup coil. 3) The device according to claim 1, wherein the filter comprises a low-pass filter that passes only each harmonic component below the fifth harmonic of the voltage of the pickup coil. Arm defect detection device.