JPH04285458A - Field abnormality detector for brushless synchronous machine - Google Patents

Abstract

PURPOSE:To detect a field abnormality without providing a special detection coil by obtaining a power factor angle by a voltage, a current, obtaining a field current at the time of loading from a field current, three-phase short-circuit rated currents corresponding to a non load rated terminal voltage corrected by the angle and a frequency, and comparing it with an actual field current. CONSTITUTION:A phase angle is detected by a phase angle detector 23 by outputs of a current detector 21 and a voltage detector 22, a correction value of a field current with respect to a no load rated terminal voltage is calculated by a field current corrector 28 based on a frequency detected by a frequency detector 27, and a correction value of a three-phase short-circuit rated current is calculated by a field current corrector 29. A field current at the time of loading is obtained by a field current calculator 30 by using them, compared with actual field current detected by a field, current detector 31 by a comparator 32 to detect a field abnormality.

Description

[Detailed description of the invention]

[Object of the invention]

0002

[Industrial Application Field] The present invention is applicable to a brushless synchronous machine, in which an abnormality in the armature circuit of an AC exciter provided on the same axis, an abnormality in the field circuit of a main synchronous machine, and a method for rectifying the voltage of the AC exciter. The present invention relates to a field abnormality detection device for a brushless synchronous machine that detects a failure of a rectifier provided for supplying current to the field of a main synchronous machine.

0003

2. Description of the Related Art A conventional brushless synchronous machine will be explained with reference to the block diagram shown in FIG. In FIG. 5, 1 is the armature winding of the main synchronous machine, 2 is the field winding of the main synchronous machine, 3 is the rotating rectifier, and 4
is the armature winding of the AC exciter; 5 is the field winding of the AC exciter; among these, the field winding 2 of the main synchronous machine, the rotary rectifier 3, and the armature winding 4 of the AC exciter; is mounted on the rotating shaft 6. 7 is an automatic voltage regulator (hereinafter referred to as AVR), which controls the output voltage of the brushless synchronous machine to be constant. Reference numeral 16 is a transformer for detecting the voltage of the AVR 7, and reference numeral 17 is a current transformer for detecting the output current for a cross current compensator provided when the brushless synchronous machines are operated in parallel.

In the brushless synchronous machine configured as described above, if a short circuit or an open circuit failure occurs in the rectifying element constituting the rotary rectifier 3 for some reason, the armature winding 4 of the AC exciter and other healthy components will be damaged. Since there is a risk that the rectifying element may become overloaded and the failure may spread, it is necessary to take measures such as stopping the brushless synchronous machine.

[0005] Therefore, if a failure occurs in the rotating rectifier,
Various methods for detecting such failures have been studied in the past. As an example, as shown in FIG. 6, a detection coil 9 is provided between the field magnetic poles 8 and 8 of an AC exciter, and the frequency components of the pulsating voltage induced therein are different when the rotary rectifier is normal and when it is malfunctioning. There is a known method for detecting a failure in a rotating rectifier by determining its frequency components using a filter circuit (see Japanese Patent Publication No. 12469/1983).
. In this fault detection method, the frequency component included in the voltage waveform induced in the detection coil 9 is six times (three-phase full-wave rectification system) or three times (three-phase full-wave rectification system) the armature voltage frequency of the AC exciter when the rotating rectifier is normal. The frequency of phase/half wave rectification method is
Furthermore, when a rotary rectifier fails, frequency components that are one and two times the frequency of the armature voltage of the AC exciter are generated depending on the failure mode, so only a specific frequency f1 as shown in Fig. 8 is passed through this frequency. A failure of the rotary rectifier is detected by using an active filter circuit with specific characteristics to pass or cut off the voltage induced in the detection coil 9 depending on its frequency component. Therefore, the characteristics of this active filter circuit are adjusted to the frequency of the armature voltage of the AC exciter at the rated rotation speed of the brushless synchronous machine, and the configuration diagram shown in Fig. 7 is used as a field abnormality detection device. It has been known.

In FIG. 7, 9 is a detection coil, 10 is a limiter circuit for preventing excessive voltage from being applied to the active filter when a high voltage is induced due to a transient state of the brushless synchronous machine, and 11 is an active filter circuit. , 12 is a comparison circuit that compares the output voltage of the active filter circuit 11 with a set value provided internally, and generates a fault signal for the rectifier based on the comparison result; 13 is a comparison circuit that compares the output voltage of the active filter circuit 11 with a set value provided inside; This is a relay circuit that operates a relay and outputs a contact output. 14 is a rotation speed relay that outputs 1 when the brushless synchronous machine is at the rated rotation speed, and 15 is an AND circuit that inputs the output signals of the relay circuit 13 and the rotation speed relay circuit 14 so as to operate at the rated rotation speed. There is.

[0007]

[Problems to be Solved by the Invention] In the conventional detection device configured as described above, in order to detect a failure in the rotating rectifier of a brushless synchronous machine, as shown in FIG. , 8 must be provided with a detection coil 9 between them. This detection coil 9 can be provided relatively easily when a brushless synchronous machine is newly manufactured, but it is not easy to provide a detection coil in an existing brushless synchronous machine. Therefore, it is almost impossible to install a rotary rectifier failure detection device in an existing brushless synchronous machine. Furthermore, conventional detection devices have the problem of being able to detect only failures in the rotary rectifier and not detecting abnormalities such as ground faults in the field circuit.

The present invention has been made to solve the above problems, and its purpose is to provide a brushless synchronous machine with a special method for detecting abnormalities not only in the rotating rectifier of the brushless synchronous machine but also in the field circuit such as field ground faults. It is an object of the present invention to provide a field abnormality detection device that can reliably detect abnormalities in a field circuit without providing a coil. [Structure of the invention]

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a rotating field type main synchronous machine and a rotating armature type AC exciter on the same axis, and the AC exciter In the brushless synchronous machine, the output of the main synchronous machine is converted into DC by a rectifier provided on the same axis to excite the field of the main synchronous machine. a frequency detection circuit that detects a frequency from a terminal voltage of the machine; a current detection circuit that detects an output current of the brushless synchronous machine; and a phase angle detection circuit that detects a power factor angle using the voltage detection circuit and the current detection circuit. ,
a first field current calculation circuit that calculates a field current of the AC exciter corresponding to the terminal voltage based on the voltage detection output and the saturation rate correction signal; and a rated circuit connected to the output of the first field current calculation circuit. a first field current calculation correction circuit that divides the frequency by the square of the actual detected frequency; and a second field current that calculates a field current corresponding to the output current of the brushless synchronous machine based on the output of the current detection circuit. a calculation circuit, a second field current calculation correction circuit connected to the output of the second field current calculation circuit that divides the rated frequency by the actual detection frequency, the phase angle detection circuit and the first field current calculation circuit; a field current calculation circuit which receives the outputs of the current calculation correction circuit and the second field current calculation correction circuit and calculates the field current at a certain load; A comparison circuit is provided which compares the output of the field current detection circuit to be detected, the output of the field current calculation circuit, and the output of the field current detection circuit, and generates a field abnormality of the brushless synchronous machine based on the comparison result. This is a characteristic feature.

0010

[Operation] The present invention inputs the terminal voltage and output current of a brushless synchronous machine, calculates the power factor angle φ from the voltage and current, calculates the field current of the AC exciter at a certain load, and further corrects it by frequency. It is possible to compare the field current obtained by adding the above with the field current of the actual AC exciter, and detect field abnormalities in the brushless synchronous machine based on the comparison results.

[0011]

[Embodiments] Hereinafter, embodiments of the present invention will be explained with reference to the drawings. FIG. 4 is a circuit configuration diagram to which the present invention is applied, and the same components as those in FIG. 5 already explained are given the same reference numerals and explained.

In FIG. 4, 1 is the armature winding of the main synchronous machine, 2 is the field winding of the main synchronous machine, 3 is the rotating rectifier, 4 is the armature winding of the AC exciter, and 5 is the AC exciter. Of these, the field winding 2 of the main synchronous machine, the rotary rectifier 3
, the armature winding 4 of the AC exciter is mounted on a rotating shaft 6. 7 is an AVR, which controls the output voltage of the brushless synchronous machine to be constant. Reference numeral 16 is a transformer for detecting the voltage of the AVR 7, and reference numeral 17 is a current transformer for detecting the output current for a cross-current compensator provided when the brushless synchronous machines are operated in parallel. 18 is a field abnormality detection device, and 16a and 17a are transformers and current transformers for detecting the terminal voltage and output current of the brushless synchronous machine in the field abnormality detection device. Further, 19 is a field current detection sensor that detects the field current of the AC exciter. The field current relative to the output of a brushless synchronous machine is determined by the load saturation curve, which is a curve showing the relationship between the terminal voltage and field current when a load of rated speed, constant power factor, and constant current is applied as shown in Figure 2. It is expressed by this curve. This load saturation curve is as follows: If the field current for the no-load rated terminal voltage from the no-load saturation curve is If1, and the three-phase short-circuit rated current from the short-circuit curve is If2, the terminal voltage Et, the output current IG, and the power factor cosφ
The field current If3 at this time is determined by the following equation (1).

[0013]

[Math 1]

In general, brushless synchronous machines are used at the rated rotation speed, but in special applications, the no-load saturation curve and three-phase short circuit curve when the rotation speed is 50% of the rated rotation speed are As shown in Figure 3, the field current for the no-load rated terminal voltage is four times the value at the rated rotation speed, and the field current for the rated current at three-phase short circuit is four times the value at the rated rotation speed. The value will be twice the value. In order to detect abnormalities in the field circuit of a brushless synchronous machine whose rotational speed changes in this way, the present invention is based on the principle of equation (1) above and is constructed in consideration of fluctuations in the rotational speed. be.

FIG. 1 is a block diagram of an embodiment of the present invention. In FIG. 1, 21 is a current detection circuit that detects the output current IG of the brushless synchronous machine, and 22 is a terminal voltage V
23 is a phase angle detection circuit that calculates the power factor angle φ from the outputs of the current detection circuit and the voltage detection circuit. 24 is a second field that calculates the field current If2 corresponding to the output current. The magnetic current calculation circuit 25 is a setting device for correcting the saturation rate of the terminal voltage of the brushless synchronous machine, and setting is performed by each brushless synchronous machine. 26 is a first field current calculation circuit that calculates a field current If1 corresponding to the terminal voltage based on the terminal voltage detection signal and the saturation rate correction signal. 27 is a frequency detection circuit that detects the frequency from the terminal voltage; 28 is a second field current calculation correction circuit that divides the rated frequency by the actual frequency from the frequency detection circuit 27; the second field current calculation circuit 24; is multiplied by 29 is a first field current calculation correction circuit that divides the rated rotational speed by the square of the actual frequency from the frequency detection circuit 27, which is multiplied by the first field current calculation circuit 26. 30 indicates the field current at the time of load of the brushless synchronous machine which receives the output signals of the phase angle detection circuit 23, the first field current calculation correction circuit 29, and the second field current calculation correction circuit 28. This is a field current calculation circuit that calculates the above equation (1). 31 is a field current detection circuit that detects the actual field current of the AC exciter; 32 is a comparison circuit that compares the output of the field current calculation circuit 30 and the output of the field current detection circuit 31; When the output of the field current detection circuit 31 becomes larger than the output of the magnetic current calculation circuit 30, it is determined that there is some abnormality in the field circuit of the brushless synchronous machine, and this comparison circuit 3
2 to detect field abnormality of the brushless synchronous machine. However, although it is difficult to necessarily match due to the temperature of the brushless synchronous machine, under normal conditions, the difference is about 20% from experience. When a rotary rectifier actually fails, the field current increases by about 50% even in the case of an open circuit failure, which has the smallest difference, although it depends on the failure mode. Therefore, the setting value of the comparator circuit 32 is set by about 30% with respect to the field current calculation value.
It may be set to operate when the actual measured value of the field current becomes large. A rectifier failure is generally a short circuit failure, in which case the current increases by as much as 200-300%. 33 is (within the field circuit time constant) during transient times when the load is turned on and off (within the field circuit time constant).
1) This is a timer circuit that determines that the field is abnormal if it continues for a certain period of time because the formula may not be satisfied. 34 is an output circuit for outputting a field abnormality signal to the outside, and is composed of, for example, a relay.

The operation of the embodiment of the present invention constructed as described above will be explained below. If the field circuit including the rotary rectifier of the brushless synchronous machine is normal, the field current value calculated by the field current calculation circuit using equation (1) from the terminal voltage, output current, and their phase angle, and the actual AC excitation. The field current of the machine may differ slightly depending on the temperature of the brushless synchronous machine, but it is almost the same. In this case, the comparator circuit 32 does not operate, so it does not operate as a field anomaly detection device. If there is a failure in the rotary rectifier, compared to the field current calculated from the terminal voltage and output current of the brushless synchronous machine, if one element of the rotary rectifier is short-circuited, the output of the AC exciter will vary between the rotary rectifiers in a certain phase. Short-circuit current flows and insufficient current is supplied to the field of the main synchronous machine. Therefore, the output voltage of the brushless synchronous machine decreases. When the output voltage of the brushless synchronous machine decreases, the AVR increases the field current of the AC exciter to control the terminal voltage to the rated value. As a result, even though the calculated value of the field current is approximately constant with the normal value, the actual field current of the AC exciter increases significantly compared to the normal value of the field current. As a result, the comparison circuit determines that there is a field anomaly.

The above explanation has been made regarding a failure of the rotating rectifier, but if there is an abnormality in the field circuit other than a failure of the rectifier, and there is a difference between the calculated value and the actual value of the field current, the field It can be detected as a magnetic failure. Furthermore, although the frequency is used as an element of the rotation speed of the brushless synchronous machine, the actual rotation speed may be detected and used instead of the frequency. Although the rotary rectifier of the brushless synchronous machine has been described using a three-phase full-wave circuit, the present invention can be applied as is to a three-phase half-wave circuit.

[0018]

As explained above, according to the present invention, a special detection coil is installed in the brushless synchronous machine to detect not only failures in the rotating rectifier of the brushless synchronous machine but also abnormalities in the field circuit such as field ground faults. It is possible to provide a field anomaly detection device for a brushless synchronous machine that can detect it without any rotational speed of the brushless synchronous machine.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a characteristic curve diagram for explaining the principle of field anomaly detection according to the present invention.

FIG. 3 is a characteristic curve diagram for explaining the principle of field anomaly detection according to the present invention.

FIG. 4 is a configuration diagram of an excitation circuit to which the field anomaly detection device of the present invention is applied.

FIG. 5 is an excitation circuit configuration diagram of a brushless synchronous machine.

FIG. 6 is a configuration diagram when a detection coil is provided for a field abnormality detection device for a conventional brushless synchronous machine.

FIG. 7 is a block configuration diagram of a conventional field abnormality detection device for a brushless synchronous machine.

FIG. 8 is a frequency characteristic diagram of a filter circuit used in a conventional field abnormality detection device for a brushless synchronous machine.

[Explanation of symbols]

1... Armature winding of the main synchronous machine, 2... Field winding of the main synchronous machine,
3... Rotating rectifier, 4... Armature winding of AC exciter, 5... Field winding of AC exciter, 6... Rotating shaft, 7... AVR (automatic voltage regulator), 8... Field of AC exciter Magnetic pole, 9...detection coil, 16, 16a...transformer, 17, 17a...current transformer,
18... Field abnormality detection device, 19... Sensor.

Claims (1)

[Claims] Claim 1: A rotating field type main synchronous machine and a rotating armature type AC exciter are provided on the same axis, and the output of the AC exciter is converted into DC by a rectifier provided on the same axis. , in the brushless synchronous machine that excites the field of the main synchronous machine, a voltage detection circuit that detects the terminal voltage of the brushless synchronous machine, a frequency detection circuit that detects a frequency from the terminal voltage of the brushless synchronous machine, and the brushless synchronous machine that excites the field of the main synchronous machine. a current detection circuit that detects the output current of the synchronous machine; a phase angle detection circuit that detects the power factor angle using the voltage detection circuit and the current detection circuit; and an AC that corresponds to the terminal voltage using the voltage detection output and the saturation rate correction signal. a first field current calculation circuit that calculates the field current of the exciter; and a first field current calculation circuit that divides the rated frequency connected to the output of the first field current calculation circuit by the square of the actual detected frequency.
a field current calculation correction circuit; a second field current calculation circuit that calculates a field current corresponding to the output current of the brushless synchronous machine based on the output of the current detection circuit; and the second field current calculation circuit. a second field current calculation correction circuit that divides the rated frequency connected to the output of the circuit by the actual detection frequency; the phase angle detection circuit; the first field current calculation correction circuit; and the second field current calculation correction circuit. a field current calculation circuit that takes each output of the circuit as input and calculates the field current at a certain load; a field current detection circuit that detects the actual field current of the AC exciter; and the field current. 1. A field abnormality detection device for a brushless synchronous machine, comprising a comparison circuit that compares the output of an arithmetic circuit and the output of a field current detection circuit, and generates a field abnormality of the brushless synchronous machine based on the comparison result.