JPH04285459A - Field abnormality detector for brushless synchronous machine - Google Patents

Abstract

PURPOSE:To detect a field abnormality without providing a special detector by obtaining a field current at the time of loading from a power factor angle obtained from a voltage, a current, a field current corresponding to a no-load rated terminal voltage, three-phase short-circuit rated currents and comparing it with an actual field current. CONSTITUTION:A current, a voltage of a brushless synchronous machine are detected by a current detector 21, a voltage detector 22. On the basis of them, a phase angle is detected by a phase angle detector 23, a field current corresponding to an output current is detected by a field current calculator 24, and a field current corresponding to a terminal voltage is calculated by a field current calculator 26. A field current calculator 27 inputs them and obtains a field current at the time of loading, which is compared with an actual field current detected by a field current detector 31 by a comparator 29 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. 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, 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. 5, 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. A method has been proposed for detecting a failure in a rotary 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 the phase-half-wave rectification system (phase/half-wave rectification system) is 1 and 2 times the frequency of the armature voltage of the AC exciter, depending on the failure mode when the rotary rectifier fails, so this frequency is shown in Figure 7. An active filter circuit having a characteristic of passing only a specific frequency f1 as shown in FIG.
It is designed to detect failures in the rotating rectifier. 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 Figure 6 is known as a field abnormality detection device. It is being

In FIG. 6, 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 the detection coil 9 in an existing brushless synchronous machine. Therefore, it is extremely difficult to install a rotating rectifier failure detection device in an existing brushless synchronous machine, and
Conventional detection devices have problems such as being able to detect only failures in the rotating 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 solve not only the rotary rectifier of a brushless synchronous machine but also the field circuit abnormalities such as field ground faults by using a special method for brushless synchronous machines. 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 detection 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 The brushless synchronous machine converts the output of the motor into direct current using a rectifier provided on the same axis to excite the field of the main synchronous machine, and includes a voltage detection circuit that detects the terminal voltage of the brushless synchronous machine and a voltage detection circuit that detects the output current. A current detection circuit for detecting, a phase angle detection circuit for detecting a power factor angle from the voltage detection circuit and the current detection circuit, and a field current of the AC exciter corresponding to the terminal voltage based on the voltage detection output and the saturation rate correction signal. a first field current calculation circuit that calculates a field current, 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 phase angle detection circuit. and a field current calculation circuit which takes as input the outputs of the first field current calculation circuit and the second field current calculation circuit and calculates the field current at a certain load, and the field current calculation circuit of the AC exciter. A field current detection circuit for detecting current, and a comparison circuit that compares 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. It is characterized by this.

0010

[Operation] The present invention inputs the terminal voltage and output current of a brushless synchronous machine, calculates the power factor angle from the voltage and current, calculates the field current of the AC exciter at a certain load,
The calculated field current is compared with the actual field current of the AC exciter, and field abnormalities in the brushless synchronous machine can be detected based on the comparison results.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 3 is a circuit configuration diagram to which the present invention is applied, and the same components as those in FIG. 4 already explained will be described with the same reference numerals.

In FIG. 3, 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. 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, then the terminal voltage Et is the output current IG, and the power factor cosφ. The field current If3 is determined by the following equation (1).

[0013]

[Math 1]

FIG. 1 is a block diagram of an embodiment of the present invention, and this diagram is based on the above equation (1). In FIG. 1, 21 is a current detection circuit that detects the output current IG of the brushless synchronous machine, 22 is a voltage detection circuit that detects the terminal voltage VG of the brushless synchronous machine, and 23 is a power factor from the output of the current detection circuit and the voltage detection circuit. A phase angle detection circuit that calculates the angle φ, 24 a second field current calculation circuit that calculates a field current If2 corresponding to the output current, and 25 a setting device that corrects the saturation rate of the terminal voltage of the brushless synchronous machine. , settings are made 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 calculates the field current If3 when the brushless synchronous machine is loaded, inputting the output signals of the phase detection circuit 23, the first field current calculation circuit 26, and the second field current calculation circuit 24. It is a field current calculation circuit,
The above equation (1) is calculated. 28 is a field current detection circuit that detects the actual field current If of the AC exciter; 29 is a comparison circuit that compares the output of the field current calculation circuit 27 and the output of the field current detection circuit 28; Compared to the output of the magnetic current calculation circuit 27, the field current detection circuit 28
When the output becomes large, it is determined that there is some kind of abnormality in the field circuit of the brushless synchronous machine, and this comparison circuit detects the field abnormality of the brushless synchronous machine. However, although it is difficult to necessarily match due to the temperature of the brushless synchronous machine, experience shows that the difference is about 20% under normal conditions. 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 29 may be set to operate when the actual measured value of the field current increases by about 30% of the calculated value of the field current. Rectifier failure is generally a short circuit failure, in this case 200
The current increases by ~300%. 30 is a timer circuit for determining that a field abnormality occurs if the condition continues for a certain period of time, since equation (1) may not be satisfied during transient times (within the field circuit time constant) when the load is turned on or off (within the field circuit time constant). 31 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 in this way 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 29 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.

[0016] 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 of the field current and the actual value, the field current will also occur in this case. It can be detected as a magnetic failure. 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.

[0017]

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. Therefore, it is possible to provide a field anomaly detection device for a brushless synchronous machine that can detect the field anomaly without having to do so.

[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 circuit configuration diagram to which the field anomaly detection device of the present invention is applied.

FIG. 4 is an excitation circuit configuration diagram of a brushless synchronous machine.

FIG. 5 is a configuration diagram when a detection coil is provided for a field abnormality detection device for a conventional brushless synchronous machine.

FIG. 6 is a block configuration diagram of a conventional field abnormality detection device for a brushless synchronous machine.

FIG. 7 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 a terminal voltage of the brushless synchronous machine, a current detection circuit that detects an output current, the voltage detection circuit and the current detection circuit. a phase angle detection circuit that detects the power factor angle from the voltage detection output and the saturation factor correction signal;
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; a field current calculation circuit that receives the outputs of the magnetic current calculation circuit and the second field current calculation circuit and calculates the field current at a certain load; and a field current calculation circuit that detects the field current of the AC exciter. A magnetic current detection circuit, and a comparison circuit that compares 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. Field abnormality detection device for brushless synchronous machines.