JPH0442919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling a motor generator so that its output frequency is automatically maintained at a set value.

Conventionally, there has been a device of this type as shown in FIG. In the figure, 1 is an AC motor, 2 is an electromagnetic coupling, 2a is its field winding, 3 is a generator, 4 is a disconnector, 5 is a step-down transformer, 6 is a frequency/voltage converter, and 7 is an input 10 is a deviation amplification circuit combining a resistor 8 and a capacitor 9, 11 is a phase control circuit for the thyristor 13, 12 is a firing circuit,
14 is an automatic frequency control circuit for the generator 3; 15, 1
6 is a frequency setting device, 17 is an automatic synchronization input device 18
19 is a normally open contact for the active power sharing device 20.

Next, the operation will be explained. Frequency control of the generator 3 is performed by determining how the rotation of the AC motor 1, which rotates at a substantially constant speed, is transmitted to the generator 3. It is done by controlling. For example, in the case of single machine operation, the set input voltage value set by the manual frequency setters 15 and 16 is compared with the output of the frequency/voltage converter 6, and the deviation is inputted to the deviation amplification circuit 10. At this time, if the set input voltage value is larger, the output of the deviation amplifier circuit 10 advances the phase of the thyristor 13 via the phase control circuit 11 and the ignition circuit 12, thereby causing the field winding 2a to The current is increased and the output frequency of the generator 3 is increased. Conversely, if the set input voltage value is smaller, the output of the deviation amplifier circuit 10 passes through the phase control circuit 11 and the ignition circuit 12, delays the phase of the thyristor 13, and delays the phase of the thyristor 13.
The current flowing through a is reduced, and the output frequency of the generator 3 is lowered. Further, at the start of automatic synchronization, the normally open contact 17 is closed, and frequency equalization is performed by a speed equalization signal from the automatic synchronization device 18. Next, in parallel input, the contact 17 that was closed in the previous automatic synchronization input is opened, the contact 19 is closed this time, and active power sharing is performed by the sharing signal from the active power sharing device 20.

Since the conventional automatic frequency control device is configured as described above, when the setting signal disappears due to a failure of the frequency setters 15, 16 or a cable break, the output frequency of the generator 3 changes according to the amount of signal. However, there were drawbacks that could lead to serious failures such as power outages and system failures. In addition, when cutting the uniform speed signal at the completion of automatic synchronization, or cutting the active power sharing signal when switching from parallel operation to individual operation,
Disturbance is applied to the system according to the amount of signal. Furthermore, when settings can be made at two or more locations, there is also the drawback that the setting value of one setting device affects the frequency adjustment range of the remaining setting devices.

This invention maintains the previous state even in the event of a cable break by providing two setting input circuits for raising and lowering that can change the set value only when the contact is closed. It is an object of the present invention to provide an automatic frequency control device for a generator that does not change the adjustment range.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, 18 is an automatic synchronization input device;
18a is a normally open contact that is closed by a frequency increase signal from this automatic synchronization device 18, and 18b is a normally open contact that is closed by a frequency decrease signal.
Further, 20 is an active power sharing device, 20a is a normally open contact that is closed by a frequency increasing signal from this active power sharing device, and 20b is a normally open contact that is closed by a frequency decreasing signal. 21 is an operating switch for increasing the set frequency, 22 is an operating switch for lowering the set frequency, 23 is a pulse generator, 24a, 24
b is a control gate circuit as the first and second setting circuits. 25 is an integration/subtraction counter that integrates the pulses from the pulse generator 23 when increasing the frequency and subtracts them when decreasing the frequency. 26 is a digital/analog converter that converts the digital output of the integration/subtraction counter 25 into an analog voltage value. Since the other elements are the same as those shown in FIG. 1, corresponding parts are designated by the same reference numerals and their explanation will be omitted.

Next, the operation will be explained. The control gate circuits 24a and 24b are connected to the operation switch 21 or 22.
The gate is opened only during the operation of the pulse generator 23 or when a frequency increase or decrease signal is generated during automatic synchronization or active power sharing, and pulses from the pulse generator 23 are transmitted to the integration/subtraction counter 25. For example, when the operation switch 21 or one of the normally open contacts 18a, 20a is closed, the control gate circuit 24a is activated, and the pulse from the pulse generator 23 is input to the integration side input of the integration/subtraction counter 25, and the integration value increases. This integrated value is converted into an analog voltage value by the digital-to-analog converter 26 and input to the deviation amplification circuit 10. In this deviation amplification circuit 10, a frequency that indicates the output frequency of the generator 3 is
The output voltage of the voltage converter 6 and the output voltage of the digital-to-analog converter 26 are compared, and if the value of the increase signal is higher than the output frequency of the generator 3,
The output of the deviation amplification circuit 10 passes through the phase control circuit 11 and the ignition circuit 12 to the thyristor 13.
phase is advanced, the field current increases, and the generator output frequency increases. Conversely, when the operating switch 22 or one of the normally open contacts 18b, 20b is closed and a lowering signal is generated, the control gate circuit 2
4b is opened, the pulse from the pulse generator 23 is now applied to the subtraction input of the integration/subtraction counter 25, and the pulse integration value decreases. As a result, the output voltage of the digital-to-analog converter 26 decreases, and the output of the deviation amplifier circuit 10 passes through the phase control circuit 11 and the firing circuit 12 to the thyristor 13.
phase is delayed and the generator frequency is lowered.

Further, if neither the up signal nor the down signal is supplied, the count value of the integration/subtraction counter 25 does not change.

In the above embodiment, a combination of an AC motor 1 and an electromagnetic coupling 2 is shown as the driving means for the motor generator 3, but a DC motor with a field winding or a variable speed motor using power electronics may also be used. However, the same effect as in the above embodiment can be obtained. Also, as a means of changing the set voltage,
Instead of the static type, which is a combination of a pulse generator, a control gate circuit, an integration/subtraction counter, and a digital/analog converter, as shown in the embodiment, an electric variable resistor operated by contact input may be used.

As described above, according to the present invention, two setting circuits are used as the external setting input circuits, which operate when the contacts are closed and stop when the contacts are open, so accidents such as failures of the setting circuits and cable breaks occur. However, the frequency setting value is maintained at the value immediately before the accident, does not require any special equipment, is easy to handle, and does not cause any inconvenience even if input at the same time as integration input and subtraction input. Furthermore, even if a disconnection occurs in the increase/decrease signal during frequency control using the increase/decrease signal from the automatic input device or the active power sharing device, frequency control can be continued bumplessly from the frequency at the time of the disconnection using the increase/decrease signal from the operating switch. Furthermore, since the operating power source can be easily separated and interfaces with other devices can be easily performed, a system with high versatility and reliability can be constructed.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a conventional automatic frequency control device, and FIG. 2 is a circuit diagram showing an automatic frequency control device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Electric motor, 2... Electromagnetic coupling, 3... AC generator, 6... Frequency/voltage converter, 10... Deviation amplification circuit, 11... Phase control circuit, 12... Ignition circuit,
13... Thyristor, 14... Frequency automatic control circuit,
18... Automatic synchronization device, 18a, 18b... Normally open contact, 20... Active power sharing device, 20a, 20b
...Normally open contact, 21, 22...Operation switch, 23...
Pulse generator, 24a, 24b...control gate circuit, 25...integration/subtraction counter, 26...digital/analog converter. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In an automatic frequency control device for a motor generator that compares the output frequency of the generator with a set value and controls the rotation speed of the generator according to the deviation, the signal of the operation switch for increasing the set frequency and Connect the signal of the normally open contact that is closed by the frequency increase signal from the automatic synchronization device and the signal of the normally open contact that is closed by the frequency increase signal of the active power sharing device, and connect any of these contacts. When the door is closed,
The first setting circuit inputs the pulse from the pulse generator to the integration input of the integration/subtraction counter, and the normal setting circuit is closed by the operation switch signal for lowering the set frequency and the frequency lowering signal from the automatic synchronization device. Connecting the signal of the open contact and the signal of the normally open contact which is closed by the frequency reduction signal of the active power sharing device,
A second setting circuit inputs the pulse from the pulse generator to the subtraction input of the integration/subtraction counter when any of these contacts is closed, and a second setting circuit that converts the count value of the integration/subtraction counter into an analog voltage. An automatic frequency control device for a motor generator, comprising a digital-to-analog converter that uses the set value.