JPH0136353B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an excitation control device for rotating equipment such as a generator, for example.

Conventionally, there has been a device of this type as shown in FIG. 1 is a generator having a field coil 2. This generator 1 is provided with an automatic voltage regulator (hereinafter simply referred to as AVR) 4.
The AVR 4 detects the output voltage of the generator 1 via the instrument transformer 3, and controls the field current of the field coil 2 according to the detected value.

On the other hand, 6 is a shunt, and its shunt field current is detected via an isolation amplifier 7. This detected value is
The deviation detector 8 compares it with the setting value of the allowable field current setting circuit 5, and detects the deviation signal. The detected deviation signal is amplified to an appropriate level via the amplifier circuit 9 and then supplied to a signal mixer (not shown) of the AVR 4. Then, the field current is limited to a permissible value or less.

By the way, this allowable value is determined by the maximum field current in relation to the temperature rise of the generator 1, and in a water-cooled generator, the maximum field current value is determined by the temperature of the cooling water. In this case, the permissible value of the field current is set to a value with a considerable margin in consideration of the worst-case temperature of the cooling water during normal continuous operation.

However, as shown in Figure 2, the allowable field current changes depending on the temperature of the generator's internal cooling water, but since the conventional excitation device for rotating equipment is configured as described above, the generator's internal cooling water Since the permissible field current can only be set at one point with respect to temperature, it ends up being set under the worst conditions as described above, which has the disadvantage that the generator cannot be used to its true limit.

In other words, when the voltage drops due to a grid fault, the AVR 4 must supply a magnetizing output to increase the field current and restore the grid voltage, but the allowable field current setting circuit 5 reversely reduces the field voltage. It limits the current. Furthermore, overexcitation of generator 1 is not a problem for a short time until the temperature rises,
In the event of an accident, bus protection relays operate and disconnect the faulty bus after a certain period of time, allowing the system voltage to recover. Therefore, constantly applying overexcitation limits with a considerable margin required for short periods of time such as during grid failures, from the perspective of the grid, will ultimately cancel out the voltage control characteristics of the grid. .

This invention was made in order to eliminate the above-mentioned drawbacks, and it is possible to change the allowable field current in inverse proportion to the temperature of the internal cooling water so that the field current can flow to the maximum capacity of rotating equipment. At the same time, if the generator voltage is higher than the normal operating range, overexcitation will be immediately limited, and if the generator is normal and the grid voltage has dropped, it will be activated within a certain period of time to contribute to grid voltage recovery. prevents the overexcitation limit function,
The maximum field current is applied by the AVR, and after a certain period of time, the shock is reduced. In order to reduce the shock after a certain period of time, the field current is limited by gradually supplying an overexcitation limit signal to the AVR using a first-order delay circuit, and the temperature change of the cooling water is The purpose of the present invention is to provide an excitation control device for rotating equipment that has both the functions of improving the stability of system voltage control and preventing overexcitation of the generator by using the generator up to its allowable capacity limit. It is something to do.

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.
This will be explained in detail with reference to the drawings.

In FIG. 3, 1 to 4 and 6 to 9 are the first
It is the same as the one shown in the figure. A cooling device 10 cools the generator 1 by circulating cooling water through a circulation path 11 . A search coil 12 is provided in a part of the circulation path 11 to detect the temperature of the cooling water.

The search coil 12 detects the temperature of the cooling water as an electrical signal via the temperature electrical signal converter 13. On the other hand, 14 is a temperature setting device for setting a predetermined temperature value (A-A in FIG. 4) corresponding to the maximum allowable temperature of the generator 1. The detection signal is supplied to the tolerance setting circuit 15 together with the setting signal of the temperature setting device 14 . The allowable value setting circuit 15 subtracts the detected value from the set value of the temperature setting device 14 to generate an allowable field current value signal (FIG. 4A) that is inversely proportional to the temperature of the internal cooling water of the generator 1. -B),
This is set to match the allowable value of the field current of the actual generator 1 as shown in FIG.

On the other hand, 16 is a first comparator that detects that the actual field current value of the generator 1 exceeds the allowable field current value of the above-mentioned allowable value setting circuit 15, and the detected state continues for a predetermined time. When this happens, a detection signal is supplied to the timer 17, 19, which is a time-limited operation and instantaneous return type. The timer 17 is set to a time limit of several seconds to several tens of seconds that the generator 1 can withstand, and when the detection signal is supplied for more than the set time, the relay 18
is excited to close the contact 18a. Further, the timer 19 has a set time that is larger than the set time of the timer 17, and has a time constant that is 2 to 3 times the time constant determined by the resistor 28 and the capacitor 29, so that the overexcitation limit signal is set. When the value approaches the final value, the relay 20 is activated and the contact 20b is opened. Reference numeral 21 denotes a relay that operates when the actual field current of the generator 1 exceeds an allowable field current value, and is used to display the operation or measure the time limit of the timer.

On the other hand, 22 is an AC/DC converter that detects the output of the generator 1 as a DC voltage. 23 is a setting device that sets the upper limit of the normal operating range of the generator voltage.
Each output of the AC/DC converter 22 and the upper limit setter 23 is supplied to a second comparator 24, respectively. The comparator 24 compares the detected generator voltage value with the voltage set value, and generates an output to operate the relay 25 when the detected generator voltage value exceeds the normal operating range, that is, the voltage set value.

Relay 25 detects whether the generator voltage is within the normal operating range and closes contact 25a and opens contact 25b. Normal operating range means between +5% and -5% of the rated voltage of the generator. If the generator voltage is +5% or more and the field current is more than the allowable field current value, the generator itself is abnormal for some reason, and in that case, contact 25a closes and contact 25b closes. is opened and an immediate overexcitation limit signal is provided to the AVR4;
It operates to give priority to the AVR4 control signal and limit the field current.

Next, if the grid voltage drops while the generator voltage is within the normal operating range, the field current will exceed the allowable field current value due to full phasing, but the relay 25 that detects the voltage of the generator 1 will be disabled. In operation, an overexcitation signal is supplied to the field coil 2. When the comparator 16 detects an excessive field current, the timer 17 operates after a set time to activate the relay 18 and close the contact 18a. As a result, from this point on, the detection signal of the deviation detector 8 is supplied to the first-order delayed operational amplifier 27 via the input resistor 26. Furthermore, the overexcitation limit signal is applied to the AVR4 through a first-order delay circuit made up of a resistor 28 and a capacitor 28.
The supply of the overexcitation signal to the field coil 2 is stopped. The first-order lag is AVR
This is for shock buffering against 4.

Then, when the overexcitation limit signal approaches the final value, the timer 19 operates to excite the relay 20, and the contact 20b is opened. As a result, since the capacitor 29 is disconnected, the first-order lag circuit is also separated and becomes a proportional amplifier, which is controlled by the proportional overexcitation limit signal until the field current becomes equal to or less than the allowable field current value.

Note that the rise of the overexcitation limit signal is a first-order delay from the time when the timer 17 operates in order to make the automatic voltage regulator 4 shockless, but even if the overexcitation limit signal is driven to near the allowable field current value, there will be a first-order delay. If the overexcitation limit signal is attached, a time delay will occur, so the above-mentioned timer 19 is installed to set the time of the overexcitation limit signal with the primary lag removed when the overexcitation limit signal approaches the allowable field current value to the point where there is no shock. This is to eliminate delays.

In addition, although the above embodiment has been explained with no exciter, it can also be applied to an excitation device with a rotary exciter such as a DC exciter or a brushless exciter, or an excitation device of other rotating equipment such as a synchronous phase modifier. can be similarly applied. Further, the same effect can be obtained even if the operational amplifier 27 uses other first-order delay means such as a magnetic amplifier or other amplifier.

As described above, according to the present invention, the allowable field current is changed in inverse proportion to the temperature of the internal cooling water of the generator, the overexcitation limiting device is removed within a certain period of time, and the overexcitation limiting signal is set to the delay circuit. The system is configured so that the overexcitation limit signal is supplied to an automatic voltage regulator through It is possible to contribute to the improvement of the overexcitation limit signal, reduce the shock given to the generator when overexcitation limit is applied, and eliminate the time delay of the overexcitation limit signal when the overexcitation limit signal approaches the allowable field current. It is also possible.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional excitation control device.
Figure 2 shows the actual temperature of the internal cooling water of the generator,
The characteristic diagram, Figure 3, shows the relationship with the allowable field current.
FIG. 4, a block diagram of an excitation control device according to an embodiment of the present invention, is a characteristic diagram for explaining the operation of the present invention. 1... Generator, 2... Field coil, 4... Automatic voltage regulator (AVR), 8... Deviation detector, 10
...Cooling device, 12...Search coil, 14...
Temperature setting device, 15...Tolerance value setting circuit, 16,2
4... Comparator, 17, 19... Timer, 18,
20, 21, 25... Relay, 23... Upper limit voltage setter, 27... Operational amplifier, 18a, 25a,
20b, 25b... Contact, 26, 28... Resistor,
29... Capacitor. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An automatic voltage regulator that controls the excitation current according to the output of the rotating equipment, a temperature detection unit that detects the temperature of the internal cooling water of the rotating equipment, and a predetermined temperature corresponding to the maximum allowable temperature of the rotating equipment. a temperature setting section that sets the temperature to , a tolerance setting circuit that subtracts the detected value of the temperature detection section from the set value of this temperature setting section and sets the subtracted value as the allowable excitation current of the rotating equipment, and this tolerance value. A deviation detection circuit that compares the allowable excitation current value of the setting circuit with the excitation current value of the above-mentioned rotating equipment and detects the deviation; a first comparator for detecting that
a first timer that operates when the detection signal of the comparator is supplied for a predetermined time or more; a second comparator that detects that the voltage of the rotating equipment exceeds the upper limit of the normal operating range; and a second comparator that detects the deviation. a first control circuit that supplies the deviation signal of the deviation detection circuit to the automatic voltage regulator as an overexcitation limit signal when both the circuit and the second comparator output detection signals;
a second control circuit that supplies the deviation signal of the deviation detection circuit to the automatic voltage regulator as an overexcitation limit signal when the voltage of the rotating equipment is within a normal operating range and the first timer operates; A rotating circuit comprising: a delay circuit for first-order delaying the overexcitation limiting signal supplied to the automatic voltage regulator by the second control circuit; and a second timer for stopping the delay circuit after a predetermined time. Equipment excitation control device.