JPH0136354B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an excitation control device for a rotating electrical machine.

Conventionally, there has been an excitation control device of this type as shown in FIG. An output voltage 1a of a generator 1, which is a rotating electric machine, is inputted to an automatic voltage regulator 3 via a voltage transformer 2. Field current 3 supplied from automatic voltage regulator 3 to field coil 4 of generator 1
a is detected by the shunt 5, supplied to the isolation amplifier 6 and amplified, and becomes a field current detection signal 6a. The field current detection signal 6a is supplied to a deviation detector 7 consisting of an adder. The deviation detector 7 is also supplied with a setting signal 8a from the setting circuit 8, and outputs a deviation signal 7a as a deviation value between the setting signal 8a and the field current detection signal 6a. Setting circuit 8
The value of the setting signal 8a is set in accordance with the maximum value of the field current that can maintain the generator 1 within the permissible temperature, that is, that can continuously supply the field coil 4. The setting signal 8a is amplified by an amplifier 9,
This becomes a control signal 9a and is input to the automatic voltage regulator 3. The automatic voltage regulator 3 has a characteristic of decreasing the field current 3a as the value of the control signal 9a increases, and is controlled so that the field current 3a does not exceed the above-mentioned maximum value. In this way, the temperature of the generator 1 is controlled to be within its permissible temperature range.

As explained above, the conventional excitation control device
The maximum value of the field current 3a that can be continuously passed through the field coil 4 is uniformly determined in relation to the maximum allowable temperature of the rotating electrical machine, and it corresponds faithfully to the actual temperature of the generator 1. Therefore, the field current 3a is not controlled. Therefore, with conventional excitation control devices, when the voltage drops due to an accident in the grid, the AVR3 needs to supply magnetizing output to restore the voltage of the grid. It has the disadvantage of being limited to a certain low value. Furthermore, if the generator is overexcited for a short time, there will be no problem until the temperature rises, and if an accident occurs, the bus protection relay etc. will operate and after a certain period of time, the faulty bus will be disconnected and the voltage of the system will be restored.
Therefore, even in such a case, if the overexcitation limit with the above-mentioned margin is always applied, when considered from the viewpoint of the system, there is a drawback that the voltage control characteristics of the system are canceled out.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and it detects the temperature of the cooling water of a rotating electrical machine, and in response to this temperature, continuously connects the field coil of the rotating electrical machine. To provide an excitation control device for a rotating electrical machine that can contribute to recovery of system voltage recovery characteristics by determining the maximum value and time of field current that can be passed through the rotating electrical machine, and using the rotating electrical machine up to its heat capacity limit according to these values. The purpose is to

An embodiment of the present invention will be described below with reference to FIG. In FIG. 2, the output voltage 1 of the generator 1
a is an automatic voltage regulator 3 via a voltage transformer 2
The field current 3a is supplied to the field coil 4 from this. The secondary side of the voltage transformer 2 is connected to a converter 10 consisting of a rectifier, which supplies a DC signal 10a proportional to the output voltage 1a to a comparator 11. The comparator 11 is supplied with a reference signal 12a having a value corresponding to the rated voltage of the output voltage 1a from the setting device 12, and the DC signal 10a exceeds the range of ±5% of the reference signal 12a. At times, the signal 11a is supplied to the relay 13.

A cooling water pipe 14a that constitutes a cooling device 14 is attached to the generator 1. Cooling water pipe 14a
is connected to the main body 15 of the cooling device 14 including a heat exchanger and a pump, thereby circulating the cooling water in the direction of the arrow shown in the figure, and also includes a search coil etc. on the outlet side of the generator 1 for detecting the temperature of the cooling water. Detector 1
6 is installed. The temperature 16a detected by the detector 16 is input to a temperature electrical signal converter 17 and converted into an electrical temperature detection signal 17a. The temperature detection signal 17a is input to the correction circuit 18 as a signal representing the temperature of the generator 1. Also,
A setting signal 19a whose value is determined corresponding to the maximum allowable temperature of the generator 1 is inputted to the correction circuit 18 from a temperature setting device 19 consisting of a voltage divider, while a temperature detection signal is input as an output of the correction circuit 18. The setting signal 19a is corrected by the setting signal 17a, that is, the setting signal 19a
A correction signal 18a that is a value obtained by subtracting the temperature detection signal 17a is outputted, and the correction signal 18a is input to the deviation detector 7. The deviation detector 7 is also supplied with the field current detection signal 6a from the amplifier 6 as described in the explanation of FIG. 1, and also receives the correction signal 18a.
A deviation signal 7a having a deviation value obtained by subtracting the field current detection signal 6a is output.

The deviation signal 7a is supplied to an amplifier 20 that amplifies a signal 52a (to be described later) and the deviation signal 7a to a saturation level.
, a contact 13c of the relay 13, one end of a contact 40b of a time limit circuit 40, which will be described later, and the first integrator 21.
and is input to the first comparator 22. First, the first comparator 22 receives a setting value V ₀ determined from a setting device (not shown) that corresponds to the allowable deviation value of the field current 3a, and from this setting value V ₀ a deviation signal is input. When 7a is large, a signal 22a is output, and this is input to the first time limit circuit 23.

FIG. 3 shows a circuit diagram of the first time limit circuit 23.
As shown, signal 22a is input to relay 24. The relay 24 has a contact 2 consisting of an a contact.
It has a contact 24b consisting of 4a and 4b contacts. Contact 24a is connected to apply voltage P to relay 25, and contact 24b is connected to apply voltage P to time-limited relay 26. The relay 25 has a contact 25a which is an a contact and a contact 23a which is a b contact (shown in FIGS. 2 and 4).
The contact 24a or the contact 25a and the time-limited operation contact 26a of the relay 26 are connected so that the voltage P is applied thereto. Therefore, the first time limit circuit 2
Reference numeral 3 denotes a return delay circuit which has the function of opening the contact 23a when the signal 22a is generated, and returning the contact 23a after a certain period of time when the signal 22a disappears.

Next, the first integrator 21 consists of a circuit as shown in FIG. As shown, the deviation signal 7a is input to an operational amplifier 28 via a resistor 27.
The resistor 27 includes a resistor 29 and a diode 30 connected in series, and a resistor 31 and a diode 32 connected in series.
are connected in series, and each is connected in parallel. Further, the connection point between the resistor 29 and the diode 30 is connected via a resistor 33 to a setter 34 consisting of a voltage divider, from which a set voltage V ₁ is supplied. Similarly, the connection point between the resistor 31 and the diode 32 is connected via a resistor 35 to a setting device 3 consisting of a voltage divider.
6, from which the set voltage V ₂ (V ₁ < V ₂ )
is supplied. A capacitor 37 and a contact 23a of the relay 25 are connected between the input and output terminals of the operational amplifier 28.
are connected in parallel. The output signal 21a of the operational amplifier 28 is supplied to a second comparator 38.

In FIG. 2, the second comparator 38 is set by a setting device 39 consisting of a voltage divider to correspond to the field current 3a and to correspond to the time during which the current can be continuously applied in excess of its maximum allowable value. A value signal 39a is supplied and outputs a signal 38a when the signal 21a is greater than the signal 39a. Signal 38a is supplied to a second timer circuit 40.

The second time limit circuit 40 has the same configuration as the first time limit circuit 23, as shown in FIG.
1, 42, 43. Relay 41 is signal 38
The relay 42 has a contact 42a and contacts 40a and 40b shown in FIG.

The third time limit circuit 44, as shown in FIG.
It is connected to a time-limited relay 45 via a contact 41c, and to a relay 46 via a contact 41c and a contact 45a of the relay 45 so as to apply a voltage P. The relay 46 has contacts 44 shown in FIG.
a, 44b. Therefore, the third time limit circuit 4
4 is a circuit that returns after a certain period of time when the contact 41c is closed.

Returning to the explanation of FIG. The amplifier 20 to which the deviation signal 7a is input has the deviation signal 7a and the signal 52a.
The amplified signal 20a is amplified by an operational amplifier, and the amplified signal 20a is supplied to the setter 47. The setting device 47 consists of a voltage divider, and the signal 2
Signal 47 at an appropriate voltage level by dividing 0a
a and supplies it to the second integrator 48.

The second integrator 48 includes a resistor 49 connected in series.
and a capacitor 50, and an operational amplifier 51 connected in parallel to the input and output terminals of the capacitor 50. A contact 13a of the relay 13 and a contact 40a of the second time limit circuit 40 are connected to the capacitor 50 in parallel. Signal 48 which is the output of second integrator 48
a is supplied to the amplifiers 9 and 52 via the contact 13b of the relay 13 and the contact 44a of the third time limit circuit 44. The output signal 52a of the amplifier 52 is input to the amplifier 20 as described above.

Finally, the deviation detector 7 detects the contact 13 of the relay 13.
c, or is connected to the amplifiers 9 and 52 via a contact 40a of the second time limit circuit 40 and a contact 44b of the third time limit circuit 44. The contact 13b, 1
3c, 40b, 44a, and 44b constitute a switch circuit as a whole.

Next, the operation will be explained. First, a case where both the output voltage 1a and the field current 3a are in a normal state will be described. Temperature 16 detected by detector 16
a has a certain correspondence with the temperature of the cooling water flowing through the cooling water pipe 14a, and therefore with the temperature of the generator 1, and is converted by the temperature electrical signal converter 17 into an electrical temperature detection signal 17a. The temperature detection signal 17a is
The signal is input to the correction circuit 18, where the setting signal 19a of the setting device 19 is corrected. That is, the correction circuit 18 outputs the temperature detection signal 1 from the setting signal 19a.
A correction signal 18a having a value obtained by subtracting 7a is output. Therefore, the correction signal 18a is corrected to decrease as the temperature of the generator 1 rises, and has a set value corresponding to the maximum current that can be passed through the field coil 4 at that temperature. The deviation detector 7 is
The correction signal 18a is input, and a deviation signal 7a is obtained as a deviation value by subtracting the field current detection signal 6a from the correction signal 18a. Under this condition, the deviation signal 7a does not exceed the set value _V0 , so the first comparator 22 does not generate the signal 22a and the first time limit circuit 23 does not open the contact 23a. Therefore, the first integrating circuit 21 cannot perform an integrating operation, and its signal 21a will never become larger than the signal 39a.
Since the second comparator 38 does not generate the signal 38a, the second and third time limit circuits 40, 44 also maintain the contacts 40a, 40b, 44a, 44b at the illustrated positions. In such a state, the deviation signal 7
Neither signal 48a nor signal 48a are supplied to amplifiers 9, 52, and automatic voltage regulator 3 operates according to output voltage 1a only.

Next, a case will be described in which the output voltage 1a is at the rated value, the system voltage decreases, and the field current 3a increases. Due to the increase in the field current 3a, the deviation signal 7a exceeds the set value V ₀ at the input of the first comparator 22, and the first comparator 22
generate a. Therefore, the first time limit circuit 23 opens the contact 23a, and the first integrator 21 starts an integrating operation. Referring to FIG. 4, when the value of the deviation signal 7a is small and the diodes 30 and 32 are not biased in the forward direction, an integrated current due to the deviation signal 7a flows only through the resistor 27. When the integration causes signal 21a of operational amplifier 28 to exceed the voltage of signal 39a, second comparator 38 generates signal 38a. If the deviation signal 7a is of a voltage that forward biases the diode 30, the integrated current flows through the resistors 27, 29 and the first integrator 21
The time constant is smaller than when only the resistor 27 is used.
Further, when the deviation signal 7a has a voltage that also forward biases the diode 32, the integrated current flows through the resistors 27, 29, and 31, and the time constant of the first integrator 21 becomes the minimum value.

In this way, three stages of integration time constants are selected according to the value of the deviation signal 7a, and the larger the deviation value, the longer it takes for the signal 38a supplied to the second time limit circuit 40 to be generated. is shortened.

When signal 38a is generated, second and third timer circuits 40, 44 open contact 40a and close contact 44a, respectively. This causes the second integrator 48 to start an integrating operation and gradually increase the signal 48a. The signal 48a with such a waveform is
It is amplified by the amplifier 9 and becomes a control signal 9a,
Since it is input to the automatic voltage regulator 3, a feedback loop regarding the field current 3a is formed here, and control to return the field current 3a to an appropriate value is started.

However, since the contacts 40a and 44a are controlled to operate for a limited time, once they are in the operating state,
The state is maintained for a certain period of time. In other words, if short-term overexcitation occurs repeatedly, the first time it is fully fused, but from the second time onwards, the temperature rise of the generator is close to its limit, so it is immediately restricted to protect the generator 1. .

Since the third time limit circuit 44 automatically returns after a certain period of time even if it is energized, the signal 48a of the second integrator 48 is interrupted by the opening of the contact 44a, and the deviation signal 7a is instead transmitted to the contact 44a. It is directly supplied to the amplifier 9 via 40b and 44b. For this reason,
In the feedback loop of the field current 3a to the automatic voltage regulator 3, the integrating circuit is removed and control delay is eliminated.

Finally, the operation when the deviation signal 7a is within a predetermined deviation value and the output voltage 1a exceeds ±5% of the rating will be described. In such a state, signal 10a exceeds signal 12a, and comparator 11 energizes relay 13. As a result, the deviation signal 7a, which is the deviation value at that point, becomes the contact point 13c.
The signal is input to amplifier 9 via. At this time, since the contact 13b is open, the signal 48a is not input to the amplifier 9. And automatic voltage regulator 3
controls the field current 3a which is its output according to the output voltage 1a and the control signal 9a, and the output voltage 1a
It works to make it the rated one.

Note that, although the above embodiment has been described in the case of an excitation control device for a generator, the present invention may be applied to other rotating electric machines and the same effects will be obtained.

As described above, according to the present invention, the allowable value is inversely proportional to the internal cooling water temperature of the rotating electric machine, and a time limit is generated that is inversely proportional to the magnitude of the field current, and within this time limit, overexcitation is limited. By allowing full fusion without supplying any signal, and if the time limit is exceeded, the overexcitation limit signal is supplied as a ramp signal at that point, so the generator can be used to its maximum heat capacity. This not only contributes to improving the voltage recovery characteristics of the grid, but also protects the generator, and since it prevents the application of rapidly changing control signals to the automatic voltage regulator, it has the effect of providing stable control.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional excitation control device, Fig. 2 is a block diagram showing an embodiment of the present invention, Fig. 3 is a circuit diagram of a time limit circuit shown in Fig. 2, and Fig. 4 is a block diagram of a conventional excitation control device. FIG. 2 is a circuit diagram of an integrator shown in FIG. 1... Generator, 3... Automatic voltage regulator, 6,
9, 20, 52...Amplifier, 11, 22, 38...
... Comparator, 21, 48 ... Integrator, 23, 40,
44...Time-limited circuit.

Claims (1)

[Claims] 1. Equipped with an automatic voltage regulator that controls the field current according to a deviation signal between a preset maximum allowable field current value of the field current of the rotating electrical machine and the detected value of the field current. An excitation control device for a rotating electrical machine, comprising: a correction circuit that reduces the maximum allowable field current value in accordance with a rise in temperature of the rotating electrical machine; and a first setting value that the deviation signal predetermines in response to an allowable deviation value. a first comparator that generates an output signal when the output signal exceeds the threshold voltage, a first timer that is activated by the output signal of the first comparator, and a first timer that is activated by the output signal of the first timer; a first integrator that starts an integration operation of the deviation signal and selects an integration time constant according to the magnitude of the deviation signal; and a first integrator that is set for a field current exceeding a maximum allowable field current. a second comparator that blocks the supply of the overexcitation limit signal until the output of the first integrator exceeds a second set value consisting of a maximum energization time, and generates an output signal when the output exceeds the second set value; a second timer circuit energized by the output signal of the second comparator;
a third time limit circuit that returns after a fixed time period after being energized by the output signal of the second comparator; and a second integrator that integrates the deviation signal by the energization of the second time limit circuit. , selects to route the output signal of the second integrator to the automatic voltage regulator via an amplifier when the third timer circuit is energized; and a switch circuit selected to guide the deviation signal to the automatic voltage regulator via the amplifier when the third time limit circuit is reset. Machine excitation control device.