JP2001061300A - Excitation controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out optimum overexcitation control according to an overexcited state. SOLUTION: A first-stage overexcitation-limiting device 16A (16B) outputs a first overexcited limit signal, when an overexcitation state reaches a first-stage overexcitation limiting line. A second-stage overexcitation-limit device 17A (17B) outputs a second overexcitation limit signal when the overexcited state reaches a second-stage overexcitation limit line. A third-stage overexcitation- limit device 18A (18B) outputs a third overexcitation limit signal, when the overexcitation state reaches a third-stage overexcitation limit line. A control signal-computing element 19A (19B) adds each overexcitation limit signal for outputting to a controller 10A (10B) as an exciting-weakening signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excitation control system applied to an excitation control system which controls a generator overexcitation state generated in a synchronous generator to perform safe and stable operation within a power generation function force curve. The present invention relates to an excitation control device having a device.

[0002]

2. Description of the Related Art Generally, an excitation system of a generator is classified into an AC excitation system using an AC excitation machine, a DC excitation system using a DC excitation machine, and a thyristor direct excitation system using a thyristor rectifier as an excitation power supply. They can be roughly classified.

Here, as an example of the excitation system, an excitation control device applied to a thyristor excitation system which is a mainstream of the current excitation system will be described with reference to FIG.

In FIG. 34, a synchronous machine 1 has a field winding 2 and an output terminal of the synchronous machine 1 is connected to a power system 5 via a main transformer 3 and a circuit breaker 4 for system parallel. I have.
The thyristor rectifier 6 is provided in an exciting circuit that excites the field winding 2 of the synchronous machine 1 via a field circuit breaker 7, and its AC input terminal is connected to the synchronous machine 1 via an exciting power supply transformer 8. 1 output terminal.

An automatic voltage regulator 9A controls the excitation of the synchronous machine 1, and an automatic voltage regulator 9B controls the excitation of the synchronous machine 1 and has the same configuration as that of the former. The input side of the control system 10A of the instep system is connected to the fuse 11A of the instep system and the instrument transformer 12A of the instep system. The control system 10A of the former system controls the gate of the thyristor of the thyristor rectifier 6 so that the output voltage of the synchronous machine 1 becomes the voltage set by the voltage setting device 13A of the former system.

The over excitation limiter 14A of the instep system receives the current of the current transformer 15A for the instep system as an input, and the over excitation limit apparatus 14A of the instep system is connected to the field winding 2 of the synchronous machine 1 for some reason. When an excessive field current flows,
The overexcitation state is detected with a time limit characteristic and output to the control system 10A of the instep system. On the other hand, the control system 10A of the instep system outputs an overexcitation limit signal and operates to limit the overexcitation limit pullback value.

On the other hand, the automatic voltage regulator 9B of the second party has the same configuration as the automatic voltage regulator 9A of the former party, and has a control device 10B of the second party, a voltage setter 13B of the second party, and an overexcitation limiting device 14B of the second party. And is connected to the output terminal of the synchronous machine 1 via a second party instrument transformer 12B and a second party fuse 11B.

The instep system and the second system share the roles of the service system and the standby system, respectively, so that the automatic voltage regulator is duplicated, and the control system 10A of the first system or the second system is used. One of the control signals of the normal system of the control device 10B is selected by means (not shown) and output to the excitation circuit.

The synchronous machine 1 generates electric power by passing a field current through the field winding 2 to generate electric power. As a result, the synchronous machine 1 is damaged.

FIG. 35 shows an over-excitation limit diagram having a time limit detection characteristic, in which the vertical axis represents the field current If (%) and the horizontal axis represents time t (second). In the figure, 100
Is an overexcitation limit pullback value, 101 is an overexcitation limit detection start set value, 102 is an overexcitation limit line, and 103 is a standby system switching limit line. Here, each limit line is set according to the magnitude of the field current If so that the detection is performed at a high speed when the field current If is large and at a low speed when the field current If is small.

While the synchronous machine 1 is operating at the rated load,
When the field current exceeds the over-excitation limit detection start set value 101 and continues for a certain period of time, an over-excitation detection alarm signal is generated by a predetermined over-excitation control line 102, and the automatic system voltage regulator 9A, Output to the automatic voltage regulator 9B,
The field current of the synchronous machine 1 is suppressed to the overexcitation limit pullback value 100. In this case, even if a predetermined time has passed, the synchronous machine 1
If the field current is not suppressed, the standby system switching limit line 1
At 03, the excitation control of the synchronous machine is switched to the standby system. When the switching to the standby system is performed due to the detection abnormality caused by the device abnormality, the operation is normally continued by the standby system.

However, if the standby system is abnormal or the system is actually in an overexcited state, the overexcitation limiting control for suppressing the field current of the synchronous machine 1 to the overexcitation pullback value will be performed in the same manner as in the normal system. Start. If the field current of the synchronous machine 1 is not suppressed even after the lapse of a predetermined time, both systems will fail, leading to a plant trip.

[0013]

As described above, during the rated load operation of the excitation control device having the dual automatic voltage regulator, the synchronous machine 1 is operated due to system fluctuations and plant operating conditions. When the state shifts to the overexcitation state, the pullback control is performed by the overexcitation limiting control. However, if the overexcitation state of the synchronous machine 1 is not suppressed even after the lapse of a predetermined time, switching to the standby system is performed. ing.

However, the current overexcitation limit control is
Since the limit control is started only when the excitation characteristic of the synchronous machine 1 reaches the overexcitation limit line having the time limit characteristic, when the synchronous machine 1 instantaneously shifts to the overexcitation state, the system detects the overexcitation. Therefore, when the system is switched to the standby system and overexcitation is also detected in the standby system, both systems of the automatic voltage regulator immediately fail, resulting in a plant trip.

Even if a plant trip caused by an overexcitation state due to an external factor such as a system fluctuation is unavoidable, a rapid and reliable limit control by an automatic voltage regulator is applied to the overexcitation state of the generator due to plant operating conditions and the like. It is necessary to improve the operability of the plant.

Therefore, the present invention has been made to solve the above-described problem. In an excitation control device, when a generator shifts to an over-excitation state, over-excitation limiting control according to the over-excitation state is performed. When it is not possible to limit the automatic voltage regulator to the normal system, the control is switched to the standby system and the overexcitation limiting control similar to that of the normal system is performed at any time. It is an object of the present invention to provide an excitation control device that prevents a plant trip caused by overexcitation of a plant as a main factor and improves operation efficiency of a plant.

[0017]

According to a first aspect of the present invention, there is provided an excitation control signal for performing excitation control of a synchronous machine so that a synchronous machine connected to a power system generates a predetermined voltage.
Automatically outputs an overexcitation limit signal for detecting the overexcitation state of the synchronous machine with the inverse time characteristic and limiting it to a predetermined overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state and set the field as a field. An excitation control device for controlling excitation of a synchronous machine having a voltage adjusting device, comprising: a plurality of overexcitation limit lines for sequentially defining a limit of overexcitation of a time limit characteristic with respect to a field current or a field voltage in a stepwise manner. And the field current signal or the field voltage signal of the synchronous machine for each overexcitation limit line,
The field current signal or the field voltage signal of the synchronous machine is individually provided for each overexcitation limit line that is equal to or greater than the overexcitation limit line. Means for limiting and returning to the overexcitation limit withdrawal value, and adding the overexcitation limit signal obtained by adding each individual overexcitation limit signal output by this means to the excitation control signal. A means for outputting is provided. According to this means, when the field current signal or the field voltage signal of the synchronous machine exceeds the overexcitation limit line sequentially determined in a plurality of steps, each individual overexcitation limit signal exceeding the overexcitation limit line is output. The signals are added to form an overexcitation limiting signal. As a result, the individual overexcitation limiting signals are sequentially added in a stepwise manner and output, so that optimal overexcitation control is quickly and reliably performed according to the overexcitation state. Therefore, it is possible to prevent the pullback delay control and the excessive control based on the overexcitation control signal that is uniformly determined as in the related art, thereby avoiding a trip of the plant.

According to a second aspect of the present invention, while the synchronous machine connected to the power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, the synchronous machine is configured to detect an overexcitation state of the synchronous machine. An automatic voltage regulator for detecting the time-dependent characteristic and adding an over-excitation limit signal for limiting to a predetermined over-excitation limit withdrawal value to the excitation control signal so as to weaken the over-excitation state to a field. In an excitation control device for performing excitation control of a synchronous machine, a plurality of overexcitation limiting lines for sequentially defining limits of overexcitation states of a time limit characteristic with respect to a field current or a field voltage and a field current of the synchronous machine. If the signal or field voltage signal of the synchronous machine is detected to be greater than or equal to one of the overexcitation limit lines, the overexcitation limit line in the most overexcited state is specified. And
Means for determining and outputting an overexcitation limit signal provided for the specified overexcitation limit line so that the overexcitation limit signal can be limited from the current overexcitation state to a predetermined overexcitation limit pullback value by the overexcitation limit signal. Means for selecting an overexcitation limit signal corresponding to the overexcitation limit line in the most overexcitation state and additionally outputting the selected signal to the excitation control signal. According to this means, when the field current signal or the field voltage signal of the synchronous machine exceeds the overexcitation limit line sequentially determined in a plurality of steps, the overexcitation in the most overexcited state that exceeds the overexcitation limit line An overexcitation limit signal corresponding to the limit line is selected and used as an overexcitation limit signal. As a result, the overexcitation limit signal is sequentially output in a stepwise manner, so that the optimal overexcitation control is quickly and reliably performed according to the overexcitation state. Therefore,
As in the prior art, it is possible to prevent delay control of pull-back and excessive control based on a uniform over-excitation control signal, thereby avoiding a trip of the plant.

According to a third aspect of the present invention, the synchronous machine connected to the power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an overexcitation state of the synchronous machine. And an automatic voltage adjusting device for additionally outputting an overexcitation suppression signal for limiting to a predetermined overexcitation limit withdrawal value to the excitation control signal so as to weaken the overexcitation state and set the field as a field. In the excitation control device for controlling,
The active power and the reactive power output from the synchronous machine are detected, and based on the detected active power signal and a predetermined coefficient, a plurality of over-excitation limit lines for sequentially defining the over-excitation limit for the reactive power are formed. Created and compared with the created over-excitation limit line, a signal obtained by adding the individual over-excitation limit signals individually provided for each over-excitation limit line in which the reactive power signal of the synchronous machine has exceeded the over-excitation limit line Means for limiting the current overexcitation state from the current overexcitation state to a predetermined overexcitation limit withdrawal value and outputting the overexcitation limit signal obtained by adding each overexcitation limit signal output by this means. And means for adding and outputting the excitation control signal to the excitation control signal. According to this means, when the reactive power signal of the synchronous machine exceeds the overexcitation limit line calculated and determined in a plurality of steps sequentially, the individual overexcitation limit signals exceeding the overexcitation limit line are added and overexcitation is performed. It is a restriction signal. As a result, the individual overexcitation limiting signals are sequentially added in a stepwise manner and output, so that optimal overexcitation control is quickly and reliably performed according to the overexcitation state. Therefore, it is possible to prevent the pullback delay control and the excessive control based on the overexcitation control signal that is uniformly determined as in the related art, thereby avoiding a trip of the plant.

According to a fourth aspect of the present invention, the synchronous machine connected to the power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an overexcitation state of the synchronous machine. And an automatic voltage adjusting device for adding and outputting an overexcitation limit signal for limiting to a predetermined overexcitation limit withdrawal value to the excitation control signal so as to weaken the overexcitation state and set the field as a field. In the excitation control device for controlling,
Detect active power and reactive power of the synchronous machine, create a plurality of over-excitation limit lines that sequentially determine the over-excitation limit for the reactive power based on the detected active power signal and a predetermined coefficient, If the reactive power signal of the synchronous machine is detected as one of the over-excitation limit lines by comparing with the created over-excitation limit lines, the over-excitation limit line for the most over-excitation state is specified, and the specified over-excitation line is determined. Means for determining and outputting an overexcitation limit signal provided for the excitation limit line such that the overexcitation limit signal can be limited from the current overexcitation state to a predetermined overexcitation limit withdrawal value by the overexcitation limit signal; Means for selecting an overexcitation limit signal corresponding to the overexcitation limit line in the state and additionally outputting the selected signal to the excitation control signal. According to this means, when the reactive power of the synchronous machine becomes equal to or more than the overexcitation limit line which is sequentially calculated in a plurality of steps and corresponds to the overexcitation limit line in the most overexcited state which is equal to or more than the overexcitation limit line. The overexcitation limit signal is used as the overexcitation limit signal. As a result, the overexcitation limit signal is sequentially output in a stepwise manner, so that the optimal overexcitation control is quickly and reliably performed according to the overexcitation state. Therefore, it is possible to prevent the pullback delay control and the excessive control based on the overexcitation control signal that is uniformly determined as in the related art, thereby avoiding a trip of the plant.

According to a fifth aspect of the present invention, there is provided the first to fourth aspects of the present invention.
In the excitation control device described above, the firing phase angle of the thyristor based on the excitation control signal is additionally output so that the firing phase angle of the thyristor based on the overexcitation limiting signal is weakened to be excited, and the output of the thyristor of the phase adjusting means is controlled. The ignition phase angle is shifted to suppress the overexcitation state of the synchronous machine. According to this means, the firing phase angle of the thyristor of the phase adjusting means is shifted according to the overexcitation control signal, and quick and reliable control according to the overexcitation state is performed.

According to a sixth aspect of the present invention, while the synchronous machine connected to the power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, the synchronous machine outputs an excitation control signal for over-excitation of the synchronous machine. An automatic voltage regulator for detecting the time-dependent characteristic and adding an over-excitation limit signal for limiting to a predetermined over-excitation limit withdrawal value to the excitation control signal so as to weaken the over-excitation state to a field. In the excitation control device that controls the excitation of a synchronous machine, the overexcitation of the time limit characteristic with respect to the field current or the field voltage is limited so that the maximum operation can be performed within the operation range according to the withstand capacity of the thyristor rectifier. Means for comparing a plurality of over-excitation limit lines determined with the field current signal or field voltage signal of the synchronous machine, and comparing the field current signal or field voltage signal of the synchronous machine with a plurality of over-excitation limit line When any of the overexcitation limit lines has been reached, the overexcitation limit line in the lowest overexcitation state is specified, and an overexcitation limit signal provided for the specified overexcitation limit line is represented by the overexcitation limit signal. A means for determining and outputting the overexcitation limit from the overexcitation state to a predetermined overexcitation limit withdrawal value, and a means for selecting and outputting the overexcitation limit signal output from the lowest overexcitation limit line to the excitation control signal. Are provided. According to this means, when the field current signal or the field voltage signal of the synchronous machine reaches a plurality of over-excitation limit lines that are determined to allow maximum operation within the operation range according to the withstand capacity of the thyristor rectifier, Among the corresponding overexcitation limit signals, the overexcitation limit signal output by the lowest overexcitation limit line is selected. With this, the overexcitation limit signal signal of the lowest overexcitation control line among the plurality of overexcitation limit lines is output, so that the optimal overexcitation control is quickly and reliably performed according to the overexcitation state. Done. Further, the operation can be performed by effectively utilizing the vicinity of the thyristor rectifier in the withstand range. Therefore, it is possible to prevent the pull-back delay control and over-control by the over-excitation control signal which is uniformly determined as in the related art, thereby avoiding a trip of the plant.

According to a seventh aspect of the present invention, while the synchronous machine connected to the power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, the synchronous machine outputs an over-excitation state. An automatic voltage regulator for detecting the time-dependent characteristic and adding an over-excitation limit signal for limiting to a predetermined over-excitation limit withdrawal value to the excitation control signal so as to weaken the over-excitation state to a field. In an excitation control device for performing excitation control of a synchronous machine, a first overexcitation limit line that defines at least one overexcitation limit of a time limit characteristic with respect to a field current is compared with a field current signal of the synchronous machine for synchronization. Means for outputting a first individual overexcitation limit signal when the field current signal of the machine is equal to or greater than the first overexcitation limit line, and at least one limit for overexcitation of the reverse time limit characteristic with respect to the field voltage. The field voltage signal of the synchronous machine is Means for outputting a second individual overexcitation limit signal when the number of lines is equal to or greater than two overexcitation limit lines, and excitation control of an addition signal obtained by adding the first individual overexcitation limit signal and the second individual overexcitation limit signal The signal is output as an additional signal. According to this means, the first individual overexcitation limit signal is output when the field current signal of the synchronous machine is equal to or greater than the first overexcitation limit line that determines at least one of the field current, and the A second individual overexcitation limiting signal is output when the magnetic voltage signal is equal to or greater than a second overexcitation limiting line that is one or more defined for the field voltage. Then, the first individual overexcitation limiting signal and the second individual overexcitation limiting signal are added to form an overexcitation limiting signal. Thereby, each first individual overexcitation limiting signal for the field current and each second individual overexcitation limiting signal for the field voltage are added and output, so that the overexcitation control is quickly performed according to the overexcitation state, And it is performed reliably. Therefore, it is possible to prevent the pullback delay control and the excessive control based on the overexcitation control signal that is uniformly determined as in the related art, thereby avoiding a trip of the plant.

According to an eighth aspect of the present invention, the synchronous machine connected to the power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage. An automatic voltage regulator for detecting the time-dependent characteristic and adding an over-excitation limit signal for limiting to a predetermined over-excitation limit withdrawal value to the excitation control signal so as to weaken the over-excitation state to a field. In an excitation control device for performing excitation control of a synchronous machine, one or more overexcitation limit lines that sequentially and sequentially define overexcitation restrictions of a time limit characteristic with respect to a field current and a field current signal of the synchronous machine are provided. Compare each overexcitation limit line,
When the field current signal of the synchronous machine is equal to or greater than the overexcitation limit line, the current overexcitation state can be limited by a signal obtained by adding each first individual overexcitation limit signal provided separately for each overexcitation limit line. Means for detecting the active power and reactive power of the synchronous machine, and based on the detected active power signal and a predetermined coefficient, one or more overexcitations for limiting the overexcitation to the reactive power. A limit line is created and compared with each created overexcitation limit line.If the reactive power signal of the synchronous machine is equal to or greater than the overexcitation limit line, each second individual overexcitation provided separately for each overexcitation limit line Means for determining and outputting the current over-excitation state by a signal obtained by adding the suppression signal, and outputting each first individual over-excitation restriction signal and each second individual over-excitation restriction signal output by this means. And the signal obtained by adding Aru Te those acceptable to provide a means for adding output to. According to this means, the first individual overexcitation limit signal is output when the field current signal of the synchronous machine is equal to or more than the overexcitation limit line defined for at least one field current, and the reactive power signal of the synchronous machine is output. Is greater than or equal to one or more overexcitation limit lines calculated with respect to the reactive power, a second individual overexcitation limit signal is output. Then, the first individual overexcitation limiting signal and the second individual overexcitation limiting signal are added to form an overexcitation limiting signal. As a result, the first individual overexcitation limiting signal and the second individual overexcitation limiting signal are added and output, so that optimum overexcitation control is quickly and reliably performed according to the overexcitation state. . Therefore, it is possible to prevent the pullback delay control and the excessive control based on the overexcitation control signal that is uniformly determined as in the related art, thereby avoiding a trip of the plant.

According to a ninth aspect of the present invention, while the synchronous machine connected to the power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, the synchronous machine is controlled to over-excited. An automatic voltage regulator for detecting the time-dependent characteristic and adding an over-excitation limit signal for limiting to a predetermined over-excitation limit withdrawal value to the excitation control signal so as to weaken the over-excitation state to a field. In an excitation control device for performing excitation control of a synchronous machine, a plurality of overexcitation limiting lines for sequentially defining the overexcitation of the time limit characteristic with respect to a field current or a field voltage and a field current signal of the synchronous machine. Or, compare with the field voltage signal, and when the field current signal or the field voltage signal of the synchronous machine exceeds the overexcitation limit line, output each overexcitation limit signal corresponding to the overexcitation limit line. And the field of the synchronous machine A change rate of the signal or the field voltage signal is calculated, and any one of the plurality of over-excitation limit lines is selected according to the calculated change rate, and an over-excitation limit signal corresponding to the selected over-excitation limit line is generated. Means for additionally outputting the excitation control signal. According to this means, when the field current signal or the field voltage signal of the synchronous machine exceeds the overexcitation limit line, each overexcitation limit signal corresponding to the overexcitation limit line is output, Either of the overexcitation limiting signals is selected according to the rate of change of the field current signal or the field voltage signal of the machine, and is used as the overexcitation limiting signal. As a result, an overexcitation limit signal is output according to the rate of change, so that overexcitation control can be quickly performed according to the overexcitation state,
And it is performed reliably. Therefore, it is possible to prevent the pull-back delay control and the excessive control based on the uniform over-excitation control signal as in the related art, thereby avoiding a trip of the plant.

According to a tenth aspect of the present invention, while the synchronous machine connected to the power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, the synchronous machine outputs an over-excitation state. An automatic voltage regulator for detecting the time-dependent characteristic and adding an over-excitation limit signal for limiting to a predetermined over-excitation limit withdrawal value to the excitation control signal so as to weaken the over-excitation state to a field. In an excitation control device that controls the excitation of a synchronous machine, a plurality of overexcitation limit lines, which are determined by sequentially calculating the overexcitation limit of the reverse time characteristic with respect to the reactive power, are compared with the reactive power signal of the synchronous machine. When the reactive power signal of the synchronous machine exceeds the overexcitation limit line, a means for outputting each overexcitation limit signal corresponding to the corresponding overexcitation limit line, and a rate of change of the reactive power signal of the synchronous machine. Calculated and according to the calculated rate of change By selecting one of a plurality of overexcitation limit line is obtained by the overexcitation limit signal corresponding to the overexcitation limit line selected to provide a means for adding outputs the excitation control signal. According to this means, when the reactive power signal of the synchronous machine is equal to or greater than the overexcitation limit line, each overexcitation limit signal corresponding to the corresponding overexcitation limit line is output,
One of the overexcitation limiting signals is selected according to the rate of change of the reactive power signal of the synchronous machine, and is used as the overexcitation limiting signal. As a result, the overexcitation limiting signal is output according to the rate of change, so that the overexcitation control is quickly and reliably performed according to the overexcitation state. Accordingly, it is possible to prevent delay control and overcontrol of pullback by a uniform overexcitation control signal as in the related art, and to avoid tripping of the plant.

According to the eleventh aspect of the present invention, the synchronous machine connected to the power system outputs an excitation control signal for performing the excitation control of the synchronous machine so as to generate a predetermined voltage, while the over-excitation state of the synchronous machine is detected. An automatic voltage regulator for detecting the time-dependent characteristic and adding an over-excitation limit signal for limiting to a predetermined over-excitation limit withdrawal value to the excitation control signal so as to weaken the over-excitation state to a field. In an excitation control device that controls the excitation of a synchronous machine, a field voltage or one or more overexcitation limit lines that sequentially and sequentially limits overexcitation of a time limit characteristic with respect to the field voltage and a field current of the synchronous machine. Means for comparing a signal or a field voltage signal and outputting an individual overexcitation limit signal according to each overexcitation limit line when the field current signal or the field voltage signal of the synchronous machine is equal to or greater than the overexcitation limit line. And the synchronous machine field current signal Or means for calculating one or more overexcitation limit lines for calculating a control gain according to a field voltage signal, and increasing or decreasing each individual overexcitation limit signal based on each individual overexcitation limit signal and the corresponding control gain. Means for adding and outputting an addition signal of the signal obtained by this to the excitation control signal. According to this means, when the field current signal or the field voltage signal of the synchronous machine is equal to or more than the overexcitation limit line, an individual overexcitation limit signal corresponding to each overexcitation limit line is output, and the field of the synchronous machine is output. The control gain is calculated according to the magnetic current signal or the field voltage signal. Then, the individual overexcitation signal is increased or decreased by the calculated control gain, and the added signal is used as the overexcitation limiting signal. As a result, the individual overexcitation limit signals are continuously increased / decreased, added and output, so that the overexcitation control is quickly and reliably performed according to the overexcitation state. Therefore, it is possible to prevent the pull-back delay control and the excessive control based on the uniform over-excitation control signal as in the related art, thereby avoiding a trip of the plant.

According to a twelfth aspect of the present invention, in the excitation control apparatus according to the eleventh aspect, the means corresponding to the one or more overexcitation limit lines for calculating the control gain includes a field current setting of the synchronous machine which can be set from the outside. The control gain is calculated in accordance with a deviation signal between the signal or the field voltage setting signal and the field current signal or the field voltage signal of the synchronous machine. According to this means, the field current setting signal or the field voltage setting signal is arbitrarily set from the outside, and the control gain is calculated based on the deviation signal based on the signal. Can be.

According to a thirteenth aspect of the present invention, the synchronous machine connected to the power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, while the synchronous machine is controlled to over-excited. An automatic voltage regulator for detecting the time-dependent characteristic and adding an over-excitation limit signal for limiting to a predetermined over-excitation limit withdrawal value to the excitation control signal so as to weaken the over-excitation state to a field. In an excitation control device that performs excitation control of the synchronous machine, the reactive power signal of the synchronous machine is compared with one or more overexcitation limit lines that sequentially and sequentially determines the overexcitation limit of the reverse time characteristic with respect to the reactive power, When the reactive power signal of the synchronous machine is equal to or greater than the overexcitation limit line, a means for outputting each individual overexcitation suppression signal according to each overexcitation limit line, and a method for calculating a control gain according to the reactive power signal of the synchronous machine. Corresponding to the overexcitation limit line Means for adding and outputting, to the excitation control signal, an addition signal of a signal obtained by increasing or decreasing each individual overexcitation limiting signal based on the means and each individual overexcitation limiting signal and the corresponding control gain. It is. According to this means, when the reactive power signal of the synchronous machine is equal to or greater than the overexcitation limit line, each individual overexcitation limit signal corresponding to each overexcitation limit line is output, and in accordance with the reactive power signal of the synchronous machine. A control gain is calculated. Then, the individual overexcitation signal is increased or decreased by the calculated control gain, and the added signal is used as the overexcitation limiting signal. As a result, the individual overexcitation limiting signals are continuously increased / decreased according to the control gain, added, and output, so that the overexcitation control is quickly and reliably performed according to the overexcitation state. Therefore, it is possible to prevent the pull-back delay control and the excessive control based on the uniform over-excitation control signal as in the related art, thereby avoiding a trip of the plant.

According to a fourteenth aspect of the present invention, in the excitation control apparatus according to the thirteenth aspect, the means corresponding to the one or more overexcitation limit lines for calculating the control gain includes a reactive power setting signal of a synchronous machine that can be set from the outside. And a control gain is calculated according to a deviation signal from the reactive power signal of the synchronous machine. According to this means, the reactive power setting signal is arbitrarily set from the outside, and the control gain is calculated based on the deviation signal based on the reactive power setting signal. Therefore, it is possible to perform appropriate overexcitation control according to the driving situation.

According to a fifteenth aspect of the present invention, there is provided control means for outputting an excitation control signal for performing excitation control of the synchronous machine so that the synchronous machine connected to the power system generates a predetermined voltage, and an over-excitation state of the synchronous machine. Over-excitation limiting means for detecting an over-excitation limit with a time limit characteristic and adding an over-excitation limit signal to the excitation control signal so as to weaken the over-excitation state and set the over-excitation state to be a field. In an excitation control device that has an automatic voltage adjustment device having a dual configuration of a normal system and a standby system and performs excitation control of a synchronous machine, the automatic voltage adjustment device of each own system is used when the own system is a normal system. Means for transmitting the overexcitation state information including the overexcitation restriction signal from the overexcitation restriction means to the overexcitation restriction means of another system. According to this means, the over-excitation state information including the over-excitation limiting signal of the service system is transmitted from the automatic voltage regulator of the service system to the automatic voltage regulator of the standby system. As a result, when the own system is switched from the standby system to the service system, overexcitation control is performed based on the overexcitation state information of the other system that was the service system.
Therefore, it is possible to avoid a plant trip mainly caused by overexcitation accompanying switching from the normal system to the standby system as in the related art, thereby improving the operation efficiency of the plant.

According to a sixteenth aspect of the present invention, there is provided a control means for outputting an excitation control signal for performing excitation control of the synchronous machine so that the synchronous machine connected to the power system generates a predetermined voltage, and an over-excitation state of the synchronous machine. Over-excitation limiting means for detecting an over-excitation limit with a time limit characteristic and adding an over-excitation limit signal to the excitation control signal so as to weaken the over-excitation state and set the over-excitation state to be a field. In an excitation control device that has an automatic voltage adjustment device having a dual configuration of a normal system and a standby system and performs excitation control of a synchronous machine, the automatic voltage adjustment device of each own system has its own system when the own system is a normal system. Means for transmitting the detected field current signal or field voltage signal of the synchronous machine and the phase signal output from the control means of the own system to the excitation state monitoring means of the other standby system; In the case of Means are provided for monitoring the correlation between the state of the phase signal of the service system and the field current signal or the field voltage signal, and switching the own system to the service system under predetermined conditions. . According to this means, the standby system excitation state monitoring means switches to the normal system when the correlation between the state of the phase signal of the normal system and the field current signal or the field voltage signal is a predetermined condition. This automatically switches the system from the standby system to the service system automatically,
Overexcitation control is performed based on the overexcitation state information of the other system that was the normal system. Therefore, it is possible to avoid the trip of the plant mainly caused by the overexcitation accompanying the switching from the normal system to the standby system as in the related art, thereby improving the operation efficiency of the plant.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an excitation control device according to a first embodiment of the present invention.

In FIG. 1, the same reference numerals as those in FIG. 34 showing the prior art denote the same or corresponding parts, and a description of the parts already described will be omitted. In the first to seventeenth embodiments described below, reference symbol A indicates a system of the instep-based automatic voltage regulator, and reference symbol B indicates a system of the second-party automatic voltage regulator.

In the first embodiment of the present invention, the first-stage over-excitation controller 16A, the second-stage over-excitation controller 17A, and the third-stage over-excitation controller 18A are controlled in the instep-system automatic voltage regulator 9A. While a signal calculator 19A is provided, a first-stage over-excitation controller 16B, a second-stage over-excitation controller 17B, a third-stage over-excitation controller 18B, and a control signal calculator 19B are provided in the second-system automatic voltage regulator 9B. This is characterized in that

With the above configuration, each current transformer 15A (1
The detection signal of the field current of the synchronous machine 1 detected in 5B) is applied to the first-stage over-excitation controller 16 of the instep system automatic voltage regulator 9A.
A, the second-stage over-excitation controller 17A and the third-stage over-excitation controller 18A are input to each other, and the first-stage over-excitation controller 16B and the second-stage over-excitation controller of the system B automatic voltage regulator 9B. 17B and input to the third-stage overexcitation controller 18B,
Overexcitation limit lines 104, 105, 1 of the synchronous machine 1 shown in FIG.
Monitoring of the overexcitation state is performed based on 06.

Here, when the field current of the synchronous machine 1 exceeds the overexcitation limit detection start set value 101 and the first stage overexcitation limit line 10
When the overexcitation state reaches 4, an overexcitation limiting signal for returning the field current of the synchronous machine 1 to the overexcitation limiting pullback value 100 is output from the first-stage overexcitation limiting device 16 </ b> A (16 </ b> B). Then, the control signal calculator 19A (19B) outputs the control device 10A (10B) so that the excitation weakening signal is added.

In this case, the overexcitation state continues even though the excitation weakening signal is added, and when the overexcitation state reaches the overexcitation limit line 105 shown in FIG. Over-excitation limiting signal to return to the over-excitation limiting withdrawal value 100 of the second stage over-excitation limiting device 17A (17B)
And is added to another overexcitation limit signal by the control signal calculator 19A (19B).

In this case, the first-stage overexcitation limiting device 16A
Since the overexcitation limit signal is still output according to (16B), addition with this overexcitation limit signal is performed. The overexcitation limiting signal after the addition is added to the control signal output from control device 10A (10B) as an excitation weakening signal.

Next, as described above, if the overexcitation state continues even though the excitation weakening signal is added, and the overexcitation state reaches the overexcitation limit line 106, as described above,
An over-excitation limiting signal for returning the field current of the synchronous machine 1 to the over-excitation limiting withdrawal value 100 is output to the third-stage over-excitation limiting device 1
8A (18B), the control signal calculator 19A
By (19B), it is added to another overexcitation limit signal.

In this case, the first-stage overexcitation limiting device 16A
(16B) and the second-stage overexcitation limiting device 17A (17B), since the overexcitation limiting signal is still being output, the addition of these overexcitation limiting signals is performed. The overexcitation limiting signal after the addition is output as an excitation weakening signal to control device 10A (10B).

As described above, when the field current of the synchronous machine 1 is overexcited, the excitation weakening signal is output from the automatic voltage regulator 9A,
9B. However, if the overexcitation state continues despite that, the next stage overexcitation limit signal is added to the current limit signal as needed at the timing when the next stage overexcitation limit line is reached. According to the present embodiment, it is possible to make full use of the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to generator overexcitation, and improve the operation efficiency of the plant.

FIG. 3 is a block diagram showing another modification of the first embodiment. This modification is implemented by inputting a field voltage instead of a field current to the overexcitation limiting device. Reference numeral 41A (41B) in FIG. 3 denotes a field voltage detector, which outputs a detection signal of the field voltage to the instep system automatic voltage regulator 9
A, Each output to the system B automatic voltage regulator 9B. With this configuration, a similar effect can be obtained.

FIG. 4 is a configuration diagram of an excitation control device according to a second embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding portions, and the description of the already described portions is omitted.

In the second embodiment, an overexcitation limit control detector 20A (20B) and an overexcitation limit control signal selector 21A are used instead of the control signal calculator 19A (19B) shown in FIG. 1 showing the first embodiment. (21B).

With the above configuration, the field current of the synchronous machine 1
The over-excitation state shown in FIG.
5 and 106, the arrival timing is detected by the over-excitation limit control detector 20A (20B), and based on this, the first over-excitation limiters 16A (16B), The second overexcitation limiting device 17A (17
B), one of the overexcitation limiting signals from the third overexcitation limiting device 18A (18B) is applied to the overexcitation limiting control signal selector 21.
A (21B). Then, the selected overexcitation limiting signal is output to control device 10A (10B) so as to be added as an excitation weakening signal.

As described above, when the field current of the synchronous machine 1 is overexcited, the excitation weakening signal is output from the automatic voltage regulator 9A,
9B. If the overexcitation state continues despite this, the next stage overexcitation limit signal is sequentially switched with the current overexcitation limit signal at the timing when the next stage overexcitation limit line is reached. According to this, it is possible to make full use of the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to generator overexcitation, and improve the operation efficiency of the plant.

FIG. 5 is a block diagram showing another modification of the second embodiment, in which a field voltage is input to the overexcitation limiting device instead of a field current. 5 in FIG.
A (41B) indicates a field voltage detector, and outputs a detection signal of the field voltage to the instep automatic voltage adjusting device 9A and the second automatic voltage adjusting device 9B. With this configuration, a similar effect can be obtained.

FIG. 6 is a configuration diagram of an excitation control device according to a third embodiment of the present invention.

In FIG. 6, FIG. 1 shows the first embodiment.
The same reference numerals denote the same or corresponding parts, and a description of the parts already described is omitted.

The third embodiment differs from the first embodiment in that the overexcitation limiting signal of the control signal calculator 19A (19B) is input to the phase adjustment circuit 22A (22B) to shift the firing phase angle. Has features.

With the above configuration, the control signal calculator 19A (1
9B) is input to the phase adjustment circuit 22A (22B), and shifts the charge to the overexcitation control signal with respect to the firing phase angle α corresponding to the overexcitation limit signal. It is limited so as not to be over-excited more than necessary.

As described above, when the field current of the synchronous machine 1 is over-excited, the excitation weakening signal is output from the automatic voltage regulator 9A,
9B. If the overexcitation state continues, the overexcitation limit signal is added to the current phase control signal at the timing when the overexcitation limit line of the next stage is reached. According to this, it is possible to make full use of the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to generator overexcitation, and improve the operation efficiency of the plant.

FIG. 7 shows a first modification of the third embodiment, in which a field voltage is input to the automatic voltage regulators 9A and 9B instead of the field current. Things. With this configuration, a similar effect can be obtained.

FIG. 8 is a configuration diagram of an excitation control device showing a second modification of the third embodiment.

In FIG. 8, the same reference numerals as those in FIG. 5 indicate the same or corresponding portions, and the description of the already described portions will be omitted. In this modification, the over-excitation limiting signal of the over-excitation limiting control signal selector 21 in the second embodiment is
A (22B) to shift the firing phase angle.

With the above configuration, the first-stage overexcitation limiting device 16
A (16B), the second-stage overexcitation limiting device 17A (17
B), an over-excitation limit control detector 20A that detects the phase control signal from the third-stage over-excitation limiting device 18A (18B) and the start timing of the over-excitation limiting control of each over-excitation limiting device.
(20B), the phase control signal to be selected is selected by the overexcitation limiting control signal selector 21A (21B), and the selected phase control signal is converted to the phase adjustment circuit 22A (22B).
, And is switched to the firing phase angle α according to the phase control signal, so that the overexcitation state is not restricted more than necessary.

As described above, when the field current of the synchronous machine 1 is overexcited, an excitation weakening signal is output from the automatic voltage regulator. If the overexcitation state continues, the phase control signal for overexcitation restriction is switched to the current phase control signal at the timing when the overexcitation limit line of the next stage is reached. According to this example, it is possible to maximize the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

FIG. 9 shows a third modification of the third embodiment, in which a detection signal of a field voltage is input to the overexcitation limiting device instead of the field current. With this configuration,
Similar effects can be obtained.

FIG. 10 is a configuration diagram of an excitation control device according to a fourth embodiment.

In FIG. 10, the same reference numerals as those in FIG. 34 showing the prior art indicate the same or corresponding portions, and the description of the already described portions will be omitted.

In the fourth embodiment, a power converter 25A is used instead of the overexcitation limiting device 14A (14B) shown in FIG.
(25B), the first function generator 29A (29B), the second function generator 30A (30B), and the third function generator 31A (3
1B), a power signal calculator 27A (27B), and a control signal calculator 19A (19B).

With the above configuration, the fuse 11A (11B)
And the output voltage of the synchronous machine 1 detected by the transformer 12A (12B) and the output current of the synchronous machine 1 detected by the transformer 24A (24B).
B), the active power and the reactive power are calculated. Then, the calculated active power is applied to the first function generator 29 of each stage.
A (29B), the second function generator 30A (30B), and the third function generator 31A (31B) are input, and a limit value of the reactive power is calculated by a function operation with each coefficient. The calculated reactive power and limit value are stored in the power signal calculator 27A, respectively.
(27B).

FIG. 11 is an operating capacity curve diagram used in the present embodiment. In the figure, when Q / et ² is plotted on the ordinate and P / et ² is plotted on the abscissa, 108, 109, and 110 show operating capacity curves, and the area surrounded by these operating capacity curves shows stable operation. It is possible range. In FIG. 11, the reactive power limit value is expressed as a first-stage power detection over-excitation limit line 111, a second-stage power detection over-excitation limit line 112, and a third-stage power detection over-excitation limit line 113. I have. For example, the power detection overexcitation limit line is represented by the following equation (1).

Q / et ² = a + bP / et ² (1) where, Q: target value of reactive power P: active power a, b: coefficient et: generator terminal voltage

Here, when the reactive power of the synchronous machine 1 rises and reaches the first-stage power detection overexcitation limiting line 111 shown in FIG. 11, an overexcitation limiting signal for drawing back the reactive power of the synchronous machine 1 Is output from the first-stage power signal calculator 27A (27B), and is added to the control signal of the controller 10A (10B) as the excitation weakening signal via the control signal calculator 19A (19B).

Next, when the reactive power continues to rise despite the excitation weakening signal being added and reaches the second-stage power detection over-excitation limiting line 112, the reactive power of the synchronous machine 1 is returned. The overexcitation limiting signal is output by the second-stage power signal calculator 27A (27B) and the control signal calculator 1
At 9A (19B), it is added to another overexcitation limit signal. In this case, the first-stage power signal calculator 27A (27
Since the overexcitation limit signal is still output from B), addition with this overexcitation limit signal is performed. The overexcitation limiting signal after the addition is added to the control device 10A (10B) as an excitation weakening signal.

As described above, when the reactive power further increases despite the excitation weakening signal being added and reaches the third-stage power detection over-excitation limit line 113, the synchronous machine 1 An overexcitation limit signal for returning the reactive power is output from the third-stage power signal calculator 27A (27B), and is added to another overexcitation limit signal by the control signal calculator 19A (19B). In this case, since the over-excitation limiting signals are still output from the first-stage power signal calculator 27A (27B) and the second-stage power signal calculator 27A (27B), these over-excitation limiting signals are output. Is added. The overexcitation limiting signal after the addition is transmitted to the control device 10A (1
0B) as an excitation weakening signal.

As described above, when the reactive power of the synchronous machine 1 rises and reaches the power detection overexcitation limit line, the synchronous machine 1 is regarded as overexcited, and the excitation weakening signal is output from the automatic voltage regulator. If the overexcitation state continues despite this, the next stage overexcitation limit signal is added to the current overexcitation limit signal as needed at the timing when the next stage power detection overexcitation limit line is reached. According to this example, it is possible to maximize the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

As another modified example of the fourth embodiment, a means using a current converter for calculating the active current and the reactive current instead of the power converter for calculating the active power and the reactive power is similarly implemented. it can. With this configuration, a similar effect can be obtained.

FIG. 12 is a block diagram of an excitation control device according to a fifth embodiment of the present invention. 12, the same reference numerals as those in FIG. 10 showing the fourth embodiment denote the same or corresponding portions, and a description of the already described portions will be omitted.

In the fifth embodiment, the first function generator 29A (29B) and the second function generator 30A (30B) shown in FIG.
B), second function generator 31A (31B), power signal calculator 27A (27B), and control signal calculator 19A (19B)
Instead of the first-stage power detection over-excitation limiter 32A (32
B), second-stage power detection over-excitation limiter 33A (33B),
It is characterized in that a third-stage power detection over-excitation limiter 34A (34B), a power detection over-excitation limit control detector 35A (35B), and a power detection over-excitation limit control signal selector 36A (36B) are provided. Have.

In this configuration, the active power and the reactive power are converted into the first-stage power detection overexcitation limiter 32A (32B), the second-stage power detection overexcitation limiter 33A (33B), and the third-stage power detection overexcitation limit. The reactive power limit value is calculated by inputting the coefficients to the units 34A (34B) and performing a function operation with each coefficient.

The limit value of the reactive power is the same as the power detection overexcitation limit line 111, 1 in FIG.
12, 113. (Example: Q / et ² = a +
bP / et ² (Q: target value of reactive power, P: active power,
a, b: coefficient, et: generator terminal voltage))

Here, when the reactive power of the synchronous machine 1 rises and reaches the first-stage power detection over-excitation limiting line 111, an over-excitation limiting signal for drawing back the reactive power of the synchronous machine 1 is transmitted to the first stage. Output from the power detection over-excitation limiter 32A (32B), and an over-excitation limit control start signal is output to the power detection over-excitation limit control detector 35A (35B).

In this case, the power detection over-excitation limit control signal selector 36A (36B) receives the first-stage power detection over-excitation limiter 32A (32B) based on the condition signal from the power over-excitation limit control detector 35A (35B). Select the overexcitation limit signal from. The selected overexcitation limit signal is output from the control device 10A.
At (10B), it is additionally output so as to be an excitation weakening signal.

Subsequently, when the reactive power continues to rise despite the addition of the excitation weakening signal and reaches the second-stage power detection over-excitation limit line 112, the reactive power of the synchronous machine 1 is pulled back. The overexcitation limit signal is output from the second-stage power detection overexcitation limiter 33A (33B), and the overexcitation limit control start signal or the power overexcitation limit control detector 35A
(35B).

In this case, the power detection over-excitation limiting control signal selector 36A (36B) uses the condition signal from the power over-excitation limiting control detector 35A (35B) to control the second stage power detection over-excitation limiting device 33A (33B). Select the overexcitation limit signal from. The selected overexcitation limit signal is output from the control device 10A.
At (10B), it is additionally output so as to be an excitation weakening signal.

Furthermore, when the reactive power continues to rise and reaches the third-stage power detection over-excitation limiting line 113 despite the addition of the excitation weakening signal, the reactive power of the synchronous machine 1 is increased as described above. Is output from the third-stage power detection over-excitation limiter 34A (34B), and an over-excitation limit control start signal is output to the power over-excitation limit control detector 35A (35B). .

In this case, the power detection over-excitation limit control signal selector 36A (36B) uses the condition signal from the power over-excitation limit control detector 35A (35B) to output the third stage power detection over-excitation limiter 34A (34B). Is selected. The selected overexcitation limit signal is output from the control device 10
A (10B) is additionally output so as to be an excitation weakening signal.

As described above, when the reactive power of the synchronous machine 1 rises and reaches the power detection overexcitation limit line, the synchronous machine 1 is regarded as overexcited, and the excitation weakening signal is output from the automatic voltage regulator. If the overexcitation state continues, the current overexcitation limit signal is switched from the current overexcitation limit signal to the next stage overexcitation limit signal when the power detection overexcitation limit line of the next stage is reached. Therefore, it is possible to make full use of the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

As another modification, the present invention can be similarly implemented by using a current converter for calculating active current and reactive current instead of a power converter for calculating active power and reactive power.

FIG. 13 is a configuration diagram of an excitation control device according to a sixth embodiment of the present invention. 13, the same reference numerals as those in FIG. 10 showing the fourth embodiment denote the same or corresponding portions, and a description of the already described portions will be omitted.

In the sixth embodiment, the control signal calculator 19A
This is characterized in that a phase adjustment circuit 22A (22B) for inputting the overexcitation limiting signal output from (19B) is provided.

According to this configuration, the control signal calculator 19A
The overexcitation limiting signal output at (19B) is a phase control signal related to the firing phase angle α of the thyristor rectifier 6,
It is input to the phase adjustment circuit 22A (22B). In the phase adjustment circuit 22A (22B), the firing phase angle based on the control signal of the control device 10A (10B) is shifted by the firing phase angle α corresponding to the overexcitation limiting signal, so that an overexcitation state is not caused more than necessary. To limit.

As described above, when the reactive power of the synchronous machine 1 rises and reaches the power detection overexcitation limit line, the synchronous machine 1 is regarded as overexcited, and the excitation weakening signal is output from the automatic voltage regulator. If the overexcitation state continues despite this, the next stage overexcitation limit signal is added to the current overexcitation limit signal as needed at the timing when the next stage power detection overexcitation limit line is reached. According to this example, it is possible to maximize the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

As another modification, the same operation and effect can be obtained by using a current converter for calculating the active current and the reactive current instead of the power converter for calculating the active power and the reactive power. .

As a modification of the fifth embodiment shown in FIG. 12, a phase adjusting circuit 22A (22B) can be provided.

According to this configuration, control signal calculator 19A
The overexcitation limiting signal output at (19B) is a phase control signal related to the firing phase angle α of the thyristor rectifier 6,
The phase is input to the phase adjustment circuit 22A (22B), and is shifted to a fixed value of the firing phase angle α according to the overexcitation limiting signal, so that the overexcitation state is restricted from being excessive.

As described above, the reactive power of the synchronous machine 1 increases,
When the power detection overexcitation limit line is reached, the synchronous machine is considered to be overexcited and an excitation weakening signal is output from the automatic voltage regulator. If the overexcitation state continues, the current overexcitation limit signal is switched from the current overexcitation limit signal to the next stage overexcitation limit signal when the power detection overexcitation limit line of the next stage is reached. According to this example, it is possible to maximize the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

As another modification, the same operation and effect can be obtained by using a current converter for calculating the active current and the reactive current instead of the power converter for calculating the active power and the reactive power. .

FIG. 15 is a configuration diagram of an excitation control device according to the seventh embodiment. In FIG. 15, the same reference numerals as those in FIG. 34 showing the related art indicate the same or corresponding portions, and the description of the already described portions is omitted.

The seventh embodiment is different from the prior art shown in FIG.
Instead of the overexcitation limiting device 14A (14B), the overexcitation limiting device 38A (38B) and the overexcitation limiting device 39A (3
9B) and the low value selection circuit 40A (40B).

With the above configuration, the overexcitation limiting device 38A (3
8B) has the overexcitation limit line 114 shown in FIG. 16, and the solid line portion in the drawing is valid. When the field current reaches the overexcitation limit line 114 or more in the illustrated region A, the overexcitation limit line 114
Is output. On the other hand, the overexcitation limiting device 39A (39B) has an overexcitation limiting line 115 different from the overexcitation limiting line 114 as shown in FIG. When the field current reaches the overexcitation limit line 115 in the region B in the drawing, an overexcitation limit signal is output. Then, the overexcitation limit signal is selected and output by the low value selection circuit 40A (40B). This control enables operation in the maximum operable range according to the tolerance curve of the device, and is a very effective means.

According to the present embodiment, it is possible to make full use of the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant. it can.

FIG. 17 is a block diagram of an excitation control device showing another first modification of the seventh embodiment, in which a field voltage is input to the overexcitation limiting device instead of a field current. It is.

As another second modification, an over-excitation limiting device and a low-value selection circuit may be provided in multiple parallel, and their outputs may be added and added to the automatic voltage regulator as an excitation weakening signal. it can. This means is applicable to both a field current detection type over-excitation limiting device and a field voltage detection type over-excitation limiting device.

FIG. 18 is a configuration diagram of an excitation control device showing an eighth embodiment of the present invention.

In FIG. 18, the same reference numerals as those in FIG. 34 showing the prior art denote the same or corresponding parts, and a description of the already described parts will be omitted.

The eighth embodiment differs from FIG. 34 in that a field voltage detection transformer 41A (41B), a voltage detection overexcitation limiting device 43A (43B), and a control signal calculator 19A (19B) are used.
This is characterized by the fact that (1) and (2) are additionally provided.

With the above configuration, in addition to the overexcitation limiting control based on the field current detection described in the related art, the field voltage of the synchronous machine 1 is detected by the field voltage detector 41A (41B), and this is detected by the voltage detection. It is input to the overexcitation limiting device 43A (43B). In the voltage detection over-excitation limiting device 43A (43B),
A voltage detection overexcitation limit line 118 and a voltage detection standby system switching restriction line 119 shown in FIG. 19 output an overexcitation limit signal for performing a limit control of an overexcitation state due to an increase in the field voltage of the synchronous machine 1. .

Then, the overexcitation limiting device 14A (14B)
And the respective overexcitation limiting signals from the voltage detection overexcitation limiting device 43A (43B) are added by the control signal calculator 19A (19B), and the added overexcitation limiting signal is added to the control device 10A.
(10B) is additionally output.

As described above, when the field current or the field voltage of the synchronous machine 1 rises and becomes over-excited and reaches any over-excitation limit line, the over-excitation limit control is started.
An excitation weakening signal is added to the control signal from the control device 10A (10B) so as to suppress the field current or the field voltage up to the overexcitation limit pullback value.

According to the present embodiment, it is possible to make full use of the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to overexcitation of the generator, and improve the operation efficiency of the plant. it can.

As another modified example, the over-excitation limiting device and the voltage detection over-excitation limiting device are multi-parallel, and their outputs are added and added to the automatic voltage adjusting device as an excitation weakening signal. You can also get the effect.

FIG. 20 is a configuration diagram of an excitation control device according to the ninth embodiment.

In FIG. 20, the same reference numerals as those in FIG. 18 showing the eighth embodiment denote the same or corresponding portions, and a description of the already described portions will be omitted.

In the ninth embodiment, a current transformer 24A for an instrument is used.
(24B), power converter 25A (25B), power signal calculator 27A (27B), and first-stage function generator 29A (29
It is characterized in that B) is provided.

With the above configuration, in addition to the overexcitation limiting control based on the detection of the field current described in the related art, the fuse 11A
(11B), the output voltage of the synchronous machine 1 detected by the instrument transformer 12A (12B), and the instrument current transformer 24A (24
B) The output current of the synchronous machine 1 detected in
5A (25B), the active power and the reactive power are calculated. Then, the calculated active power is input to the first-stage function generator 29A (29B), and a limit value of reactive power is calculated by a function operation with a coefficient.

Here, the limit value of the reactive power is the same as that described in the fourth embodiment.
11, 112, and 113.
(Example: Q / et ² = a + bP / et ² (Q: target value of reactive power, P: active power, ab: coefficient, et: generator terminal voltage))

When the calculated reactive power and limit value are input to power signal calculator 27A (27B), power signal calculator 27A (27B) calculates an overexcitation limit signal. Further, the respective overexcitation limiting signals from the overexcitation limiting device 14A (14B) and the power signal calculator 27A (27B) are added by the control signal calculator 19A (19B), and the added overexcitation limiting signal is added to the control device. It is additionally output to 10A (10B).

As described above, when the field current or the reactive power of the synchronous machine 1 rises and becomes over-excited, and reaches any over-excitation limit line, the over-excitation limit control is started.
An excitation weakening signal is added to the control device so as to suppress the field current or the reactive power up to the overexcitation limit pullback value. According to this example, it is possible to maximize the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

As a first modification of the ninth embodiment, the overexcitation limiter, the function generator and the power signal calculator are multi-parallel, and their outputs are added to form an automatic voltage regulator. There is a means to add as an excitation weakening signal. Further, as another second embodiment, there is a means using a current converter for calculating an active current and a reactive current instead of a power converter for calculating an active power and a reactive power. The same operation and effect can be obtained by any means.

FIG. 21 is a configuration diagram of an excitation control device showing a tenth embodiment of the present invention.

In FIG. 21, the same reference numerals as those in FIG. 4 showing the second embodiment denote the same or corresponding portions, and a description of the already described portions will be omitted.

In the tenth embodiment, a time setting device is used instead of the overexcitation limit control detector 20A (20B) and the overexcitation limit control signal selector 21A (21B) shown in the second embodiment shown in FIG. 44A (44B), control input change rate detector 45A (45B), change rate determiner 46A (46B), change rate detection over-excitation limiting control signal selector 50A (50B)
The feature is that it is provided.

With the above configuration, the current transformer 15A (15
The field current of the synchronous machine 1 detected in B) is the first-stage over-excitation limiting device 16A (16B) and the second-stage over-excitation limiting device 17
A (17B), third-stage overexcitation limiting device 18A (18B)
Is input to the control input change rate detector 45A (45B). In the time setting device 44A (44B), the time setting device 44
The change rate of the field current is calculated as needed based on the reference time signal output from A (44B), and the change rate determiner 46A (46)
B).

Next, the change rate determiners 46A (46B) select one of the change rate areas 1 to 3 as shown in FIG. 22 according to the calculated change rate.

On the other hand, the first-stage overexcitation limiting device 16A (16
B), the second-stage over-excitation limiting device 17A (17B), and the third-stage over-excitation limiting device 18A (18B) have over-excitation limiting lines 120 and 12 having a time limit characteristic as shown in FIG.
By 1 and 122, the overexcitation limiting control of the synchronous machine 1 is performed.

That is, the first-stage overexcitation limiting device 16A
In (16B), when the field current reaches the overexcitation limit line 120 shown in FIG. 23, an overexcitation limit signal is output. In the second-stage overexcitation limiting device 17A (17B), the field current
When an over-excitation limit line 121 shown in FIG. 3 is reached, an over-excitation limit signal is output. Third-stage overexcitation limiting device 18A (18B)
When the field current reaches the overexcitation limit line 122 shown in FIG. 23, an overexcitation limit signal is output. Each of these overexcitation limit signals is used as a change rate detection overexcitation limit control signal selector 50A.
(50B).

Change rate detection over-excitation limiting control signal selector 50
In A (50B), for example, the change rate determiner 46A (46
If the change rate region 1 is selected by B), the overexcitation limiting signal from the first-stage overexcitation limiting device 16A (16B) is output to the control device 10A (10B), and the change rate determining device 46A (46B). ), The over-excitation limiting signal from the second-stage over-excitation limiting device 17A (17B) is output to the control device 10A (10B), and the rate-of-change determining unit 46A (46B). If the rate-of-change region 3 is selected, the third-stage overexcitation limiting device 18A (18)
The overexcitation limiting signal from B) is transmitted to the controller 10A (10B).
Output to

As described above, the field current of the synchronous machine 1 increases,
When the overexcitation state is reached, the rate of change of the field current at the time of the overexcitation state is calculated, and an overexcitation limit line corresponding to the rate of change is selected. According to this example, it is possible to maximize the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

FIG. 24 is a block diagram showing another modification of the tenth embodiment, in which a field voltage is input to the overexcitation limiting device instead of the field current. Can be obtained.

FIG. 25 is a configuration diagram of an excitation control device showing an eleventh embodiment of the present invention.

In FIG. 25, the same reference numerals as those in FIG. 10 showing the fourth embodiment denote the same or corresponding portions, and a description of the already described portions will be omitted.

In the eleventh embodiment, a time setting unit 44A replaces the control signal computing unit 19A (19B) in FIG.
(44B), a control input change rate detector 45A (45B), a change rate determiner 46A (46B), and a change rate detection overexcitation limiting control signal selector 50A (50B). .

With the above configuration, the power converter 25A (25
The active power calculated in B) is the first-stage function generator 29A.
(29B), input to the second-stage function generator 30A (30B), and the third-stage function generator 31A (31B), and calculate the reactive power limit value by performing a function operation with each coefficient. Together with the reactive power detected by 25A (25B), it is input to power signal calculators 27A (27B) of each stage.

On the other hand, the reactive power is controlled by the control input change rate detector 4.
5A (45B) is input to the time setting device 44A (44
The change rate of the reactive power is calculated as needed based on the reference time signal output from B). In the change rate determiner 46A (46B), one of the same change rate regions 1 to 3 as shown in FIG. 22 is selected according to the calculated change rate (in the case of the present embodiment, FIG. The vertical axis is the reactive power.)

On the other hand, each power signal calculator 27A (27B)
The power detection overexcitation limit line 1 as shown in FIG.
Overexcitation limiting signals corresponding to 11, 112, and 113 are output to change rate detection overexcitation limiting control signal selector 50A (50B). As a result, the overexcitation limiting signal corresponding to the magnitude of the rate of change of the reactive power is selected by the change rate detection overexcitation limiting control signal selector 50A (50B), and the overexcitation limiting control of the synchronous machine 1 is performed.

As described above, the reactive power of the synchronous machine 1 increases,
When the over-excitation state is reached, the rate of change of the reactive power at the time of the over-excitation state is calculated, a power detection over-excitation limit line corresponding to the rate of change is selected, and in this case, over-excitation limit control is performed. According to the above, it is possible to make maximum use of the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to overexcitation of the generator, and improve the operation efficiency of the plant.

As another modification of the eleventh embodiment, the same effect can be obtained by using a current converter for calculating active and reactive currents instead of a power converter for calculating active and reactive powers. Obtainable.

FIG. 26 is a configuration diagram of an excitation control device showing a twelfth embodiment of the present invention.

In FIG. 26, the same reference numerals as those in FIG. 34 showing the prior art denote the same or corresponding parts, and a description of the parts already described will be omitted.

The twelfth embodiment is characterized in that a gain calculation function generator 60A (60B) is provided in FIG.

With the above configuration, the detected field current is input to the over-excitation limiting device 14A (14B) and the function generator for gain calculation 60A (60B), and the over-excitation limiting line 102 is provided as shown in FIG. Thus, the limit control of the overexcitation state due to the increase of the field current of the synchronous machine 1 is performed.

At the timing when the over-excitation limiting control is started, a gain according to the field current is calculated, and the over-excitation limiting device 14A (14B) according to the output of the gain calculating function generator 60A (60B). Over-excitation limiting signal is continuously increased or decreased, and the over-excitation limiting signal is
B).

As described above, the field current of the synchronous machine 1 increases,
When the over-excitation state is reached and the over-excitation limit line is reached, over-excitation limit control is started, and while continuously changing the control gain to the over-excitation limit pull-back value, the field current is suppressed.
The excitation weakening signal is added to the control device. According to this example,
By utilizing the overexcitation limiting control of the automatic voltage regulator to the utmost, it is possible to prevent a plant trip mainly due to the overexcitation of the generator and to improve the operation efficiency of the plant.

As another modification of the twelfth embodiment, the overexcitation limiting device and the function generator for gain calculation are multi-parallel, and their outputs are added to be added to the automatic voltage adjusting device as an excitation weakening signal. By doing so, a similar effect can be obtained.

FIG. 27 is a configuration diagram of an excitation control device showing a thirteenth embodiment of the present invention.

In FIG. 27, the same reference numerals as in FIG. 34 showing the prior art denote the same or corresponding parts, and a description of the already described parts will be omitted.

The thirteenth embodiment is different from the thirteenth embodiment shown in FIG.
A (61B) and a computing unit for gain calculation 62A (62B)
The feature is that it is provided.

With the above configuration, the field current reference value preset in the setter 61A (61B) at the timing when the overexcitation limiting control is started is substantially similar to the twelfth embodiment shown in FIG. And the field current value are calculated by a computing unit 62 for gain calculation.
A (62B), the control gain is calculated in accordance with these deviations, and output to the overexcitation limiting device 14A (14B). In the over-excitation limiting device 14A (14B), the over-excitation limiting device 14A
The overexcitation limiting signal of (14B) is continuously changed. Then, an overexcitation limit signal is additionally output to control device 10A (10B).

As described above, the field current of the synchronous machine 1 increases,
When the over-excitation state is reached and the over-excitation limit line is reached, over-excitation limit control is started, and the control device controls the control current so as to suppress the field current while continuously changing the control gain to the over-excitation limit pull-back value. An excitation weakening signal is additionally output. According to this example, it is possible to maximize the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

As another modification of the thirteenth embodiment, the overexcitation limiting device, the function generator for gain calculation and the setting device are multiparallel, and their outputs are added to reduce the excitation to the automatic voltage regulator. A similar effect can be obtained as a signal.

FIG. 28 is a configuration diagram of an excitation control device showing a fourteenth embodiment of the present invention.

In FIG. 28, the same reference numerals as those in FIG. 34 showing the prior art denote the same or corresponding parts, and a description of the already described parts will be omitted.

In the fourteenth embodiment, a power converter 25A is used instead of the overexcitation limiting device 14A (14B) of FIG.
(25B), a first-stage function generator 29A (29B), a gain calculation function generator 60A (60B), and a power detection overexcitation limiter 63A (63B).

With the above configuration, the fuse 11A (11B)
And the output voltage of the synchronous machine 1 detected by the transformer 12A (12B) and the output current of the synchronous machine 1 detected by the transformer 24A (24B).
B), the active power and the reactive power are calculated. Then, the active power is input to the first-stage function generator 29A (29B), and a limit value of the reactive power is calculated by a function operation with a coefficient.

Here, the limit value of the reactive power is the same as that described in the fourth embodiment.
11, 112, and 113.
(Example: Q / et ² = a + bP / et ² (Q: target value of reactive power, P: active power, ab: coefficient, et: generator terminal voltage))

Next, the calculated reactive power and limit value are output to power detection over-excitation limiting device 63A (63B). In the gain calculation function generator 60A (60B), a control gain according to the reactive power is calculated and output to the power detection over-excitation limiting device 63A (63B).

At the timing when the limiting control in the overexcitation state is started, a control gain according to the reactive power is calculated, and the gain calculating function generator 60A (60B)
Of the power detection over-excitation limiting device 63A (63
The overexcitation limiting signal of B) is continuously increased or decreased, and the overexcitation limiting signal is additionally output to the control device 10A (10B).

As described above, the reactive power of the synchronous machine 1 increases,
When the over-excitation state is reached and the over-excitation limit line is reached, over-excitation limit control is started, and the control device controls the reactive power so as to suppress the reactive power while continuously changing the control gain to the over-excitation limit pull-back value. An excitation weakening signal is additionally output. According to this example, it is possible to maximize the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

As a first modified example of the fourteenth embodiment, the overexcitation limiting device for power detection, the function generator for gain calculation and the function generator are multiparallel, and their outputs are added. The present invention can be implemented by adding the signal to the automatic voltage regulator as an excitation weakening signal. Further, as another second modification of the fourteenth embodiment, the same operation can be achieved by using a current converter for calculating active current and reactive current instead of a power converter for calculating active power and reactive power. The effect can be obtained.

FIG. 29 is a configuration diagram of an excitation control device showing a fifteenth embodiment of the present invention.

In FIG. 29, the same reference numerals as those in FIG. 34 showing the prior art denote the same or corresponding parts, and a description of the already described parts will be omitted.

In the fifteenth embodiment, a power converter 25A is used instead of the overexcitation limiting device 14A (14B) of FIG.
(25B), the first-stage function generator 29A (29B), the setter 61A (61B), and the gain calculator 62A (62).
B) and the provision of the power detection over-excitation limiter 63A (63B).

With the above configuration, the reactive power reference value preset in the setter 61A (61B) and the reactive power at the timing when the limit control in the overexcitation state is started, almost in the same manner as in the fourteenth embodiment. The power value and the gain calculator 62A
(62B), the control gain is calculated in accordance with these deviations, and the overexcitation limiting signal of the power detection overexcitation limiting device 63A (63B) is continuously changed in accordance with the output, and The overexcitation limit signal is output from the control device 10A (1
0B).

As described above, the reactive power of the synchronous machine 1 increases,
When the over-excitation state is reached and the over-excitation limit line is reached, over-excitation limit control is started, and the control device is excited so as to suppress the reactive power while continuously changing the control gain to the over-excitation limit pull-back value. A weak signal is added. According to this example, it is possible to maximize the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

As a first modified example of the fifteenth embodiment, the overexcitation limiting device for power detection, the function generator for gain calculation, the function generator and the setting device are multi-parallel, and each output is output. The same operation and effect can be obtained even if the sum is added and added as an excitation weakening signal to the automatic voltage regulator. The fifteenth embodiment is another second modified example in which active power and
Instead of a power converter that calculates reactive power, active current,
A similar effect can be obtained by using a current converter for calculating a reactive current.

FIG. 30 is a configuration diagram of an excitation control device according to the sixteenth embodiment.

In FIG. 30, the same reference numerals as those in FIG. 34 showing the prior art denote the same or corresponding portions, and a description of the already described portions will be omitted.

The sixteenth embodiment is characterized in that an overexcitation limit control state information transmitting device 52A (52B) is provided in FIG.

With the above arrangement, the over-excitation limit control state information transmitting means 52A (52B) can transmit the excitation control state of each other system to the over-excitation limiter 14A (14B), and the own system can control the synchronous machine. The overexcitation state continues to be detected even though the overexcitation state of No. 1 is detected and the overexcitation restriction control is performed, and even when the control is switched to the standby system, the overexcitation restriction control is immediately performed in the standby system. Will be According to this example, it is possible to maximize the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to the overexcitation of the generator, and improve the operation efficiency of the plant.

As another modification of the sixteenth embodiment, the same effect can be obtained by inputting a field voltage instead of a field current to the overexcitation limiting device as shown in FIG. be able to.

FIG. 32 is a configuration diagram of an excitation control device showing a seventeenth embodiment of the present invention.

In FIG. 32, the same reference numerals as those in FIG. 30 showing the sixteenth embodiment denote the same or corresponding portions, and a description of the already described portions will be omitted.

In the seventeenth embodiment, in FIG. 30, an excitation state determination information transmitting means 64A (64B) and an excitation information monitoring means 65A (65B) are provided instead of the over-excitation limiting control state information transmitting means 52A (52B). It is characterized by

With the above configuration, the state of the phase signal of the own system and the field current value are input by the excitation state determination information transmitting means 64A (64B), and the correlation between them is monitored. Excitation information monitoring device 65B (65
A).

Here, if the correlation between the state of the phase signal of the own system and the field current value becomes abnormal and continues for a certain period of time, it is determined that the excitation control by the own system is difficult. (65A) makes a judgment, and the system switching command is passed from the other system to the own system to the control device 10A (10B). Thereby, the control of the automatic voltage regulator is switched from the own system to the other system.

As described above, even when the control is switched to another system, the overexcitation limiting control is immediately performed in the other system. According to the present embodiment, it is possible to make full use of the overexcitation limiting control of the automatic voltage regulator, prevent a plant trip mainly due to generator overexcitation, and improve the operation efficiency of the plant.

As another modification of the seventeenth embodiment, the same operation and effect can be obtained by inputting a field voltage instead of a field current to the overexcitation limiting device as shown in FIG. be able to.

[0172]

As described above, according to the first aspect of the present invention, when the field current signal or the field voltage signal of the synchronous machine exceeds the overexcitation limit line sequentially determined in a plurality of steps,
Since each individual overexcitation limit signal is added and output, the optimal overexcitation control can be performed quickly and reliably according to the overexcitation state, and the pullback delay control by the overexcitation control signal determined uniformly as in the past And excessive control can be prevented, and a trip of the plant can be avoided.

According to the second aspect of the present invention, when the field current signal or the field voltage signal of the synchronous machine exceeds the over-excitation limit line sequentially determined in a plurality of steps, it exceeds the over-excitation limit line. Selects and outputs the overexcitation limit signal corresponding to the overexcitation limit line in the most overexcitation state, so that optimal overexcitation control can be quickly and reliably performed according to the overexcitation state, and is determined uniformly as in the past Delay control or excessive control of pullback by the overexcitation control signal can be prevented, and a trip of the plant can be avoided.

According to the third aspect of the present invention, when the reactive power signal of the synchronous machine exceeds a predetermined overexcitation limit line which is sequentially calculated in a plurality of steps, each individual overrun exceeding the overexcitation limit line is obtained. Since the over-excitation control signal is added to the over-excitation control signal, the optimal over-excitation control can be performed quickly and reliably according to the over-excitation state, and the pull-back due to the over-excitation control signal that is determined uniformly as in the past Prevent control and over control,
Plant trips can be avoided.

According to the fourth aspect of the present invention, when the reactive power of the synchronous machine exceeds the overexcitation limit line which is sequentially calculated in a plurality of steps and exceeds the overexcitation limit line, the most overexcited state becomes the overexcitation limit line or more. The over-excitation limit signal corresponding to the over-excitation limit line is output, so that the optimal over-excitation control can be performed quickly and reliably according to the over-excitation state. Delay control and excessive control can be prevented, and a plant trip can be avoided.

According to the fifth aspect of the present invention, since the firing phase angle of the thyristor of the phase adjusting means shifts according to the overexcitation control signal, quick and reliable control according to the overexcitation state is achieved. It can be carried out.

Further, according to the invention of claim 6, a plurality of overexcitations are set such that the field current signal or the field voltage signal of the synchronous machine can be operated maximally within the operation range according to the withstand capacity of the thyristor rectifier. When the limit line is reached, the overexcitation limit signal output by the lowest overexcitation limit line is selected and output from the corresponding overexcitation limit signals, so the optimal overexcitation control is performed according to the overexcitation state. The thyristor rectifier can be operated quickly and reliably, and the operation can be effectively performed in the vicinity of the thyristor rectifier in the withstand range.

According to the seventh aspect of the present invention, when the field current signal of the synchronous machine is equal to or more than the first over-excitation limit line which is one or more of the field current, it is synchronized with the first individual over-excitation limit signal. When the field voltage signal of the machine is equal to or greater than the second overexcitation limit line defined by at least one field voltage, the second individual overexcitation limit signal is added to the overexcitation limit signal, so that the overexcitation state is established. Accordingly, overexcitation control can be quickly and reliably performed, and delay control or excessive control of pullback by a uniform overexcitation control signal as in the related art can be prevented, and a trip of the plant can be avoided.

According to the eighth aspect of the present invention, when the field current signal of the synchronous machine is equal to or more than one overexcitation limit line defined for the field current, the first individual overexcitation limit signal and the synchronous machine Since the reactive power signal is calculated with respect to the reactive power and added to the second individual overexcitation limit signal that is equal to or greater than the overexcitation limit line determined as one or more, the overexcitation control signal is added. This can be performed quickly and reliably, and it is possible to prevent delay control and excessive control of pullback by a uniformly set overexcitation control signal as in the related art, thereby avoiding a trip of the plant.

According to the ninth aspect of the present invention, any one of the overexcitation limiting signals is selected according to the rate of change of the field current signal or the field voltage signal of the synchronous machine, and is used as the overexcitation limiting signal. Therefore, over-excitation control can be quickly and reliably performed according to the over-excitation state, and it is possible to prevent a pull-back delay control or excessive control by a uniform over-excitation control signal as in the past, thereby avoiding a plant trip. Can be.

According to the tenth aspect of the present invention, any one of the overexcitation limiting signals is selected according to the rate of change of the reactive power signal of the synchronous machine, and the overexcitation limiting signal is output. Over-excitation control can be performed quickly and reliably according to
It is possible to prevent delay control and overcontrol of pullback by a uniform overexcitation control signal as in the related art, thereby avoiding a trip of the plant.

According to the eleventh aspect of the present invention, a signal obtained by adding the individual overexcitation signals by the control gain calculated according to the field current signal or the field voltage signal of the synchronous machine is used as the overexcitation limit signal. Output enables quick and reliable over-excitation control according to over-excitation status, preventing pull-back delay control and excessive control by a uniform over-excitation control signal as in the past, and avoiding plant trips can do.

According to the twelfth aspect of the present invention, a field current setting signal or a field voltage setting signal is arbitrarily set externally, and a control gain is calculated based on a deviation signal based on the signal. Appropriate overexcitation control according to the above.

According to the thirteenth aspect of the present invention, a signal obtained by adding each individual overexcitation signal by the control gain calculated according to the reactive power signal of the synchronous machine is output as an overexcitation limiting signal. Over-excitation control can be performed quickly and reliably according to the state, preventing delay control and excessive control of pullback by a uniform over-excitation control signal as in the past,
Plant trips can be avoided.

According to the fourteenth aspect of the present invention, the reactive power setting signal is arbitrarily set from the outside, and the control gain is calculated based on the deviation signal based on the reactive power setting signal. You can control.

According to the fifteenth aspect, the overexcitation state information including the overexcitation limit signal of the service system is transmitted from the automatic voltage regulator of the service system to the automatic voltage regulator of the standby system. When the system is switched from the standby system to the service system, overexcitation control can be performed based on the overexcitation state information of the other system that was the service system. It is possible to improve the operation efficiency of the plant by avoiding a plant trip as a cause.

According to the invention of claim 16, when the correlation between the state of the phase signal of the service system and the field current signal or the field voltage signal is a predetermined condition by the excitation state monitoring means, the system is switched to the service system. Switching from the standby system to the service system can be automatically and smoothly performed because of the switching, and the plant can be prevented from tripping due to overexcitation caused by switching from the service system to the standby system. Operational efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an excitation control device according to a first embodiment of the present invention.

FIG. 2 is an overexcitation limit diagram used in the first embodiment of the present invention.

FIG. 3 is a configuration diagram of an excitation control device showing a modification of the first embodiment of FIG. 1;

FIG. 4 is a configuration diagram of an excitation control device according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of an excitation control device showing a modification of the second embodiment of FIG. 4;

FIG. 6 is a configuration diagram of an excitation control device showing a third embodiment of the present invention.

FIG. 7 is a configuration diagram of an excitation control device showing a modification of the third embodiment of FIG. 6;

FIG. 8 is a configuration diagram of an excitation control device showing a modification of the third embodiment of FIG. 6;

FIG. 9 is a configuration diagram of an excitation control device showing a modification of the third embodiment of FIG. 6;

FIG. 10 is a configuration diagram of an excitation control device showing a fourth embodiment of the present invention.

FIG. 11 is an operating capacity curve diagram showing a fourth embodiment of the present invention.

FIG. 12 is a configuration diagram of an excitation control device according to a fifth embodiment of the present invention.

FIG. 13 is a configuration diagram of an excitation control device showing a sixth embodiment of the present invention.

FIG. 14 is a configuration diagram of an excitation control device showing a modification of the sixth embodiment of the present invention.

FIG. 15 is a configuration diagram of an excitation control device showing a seventh embodiment of the present invention.

FIG. 16 is an overexcitation limit diagram used in a seventh embodiment of the present invention.

FIG. 17 is a configuration diagram of an excitation control device showing a modification of the seventh embodiment of FIG.

FIG. 18 is a configuration diagram of an excitation control device according to an eighth embodiment of the present invention.

FIG. 19 is an overexcitation restriction diagram used in the eighth embodiment of the present invention.

FIG. 20 is a configuration diagram of an excitation control device showing a ninth embodiment of the present invention.

FIG. 21 is a configuration diagram of an excitation control device showing a tenth embodiment of the present invention.

FIG. 22 is a change rate detection diagram used in the tenth embodiment of the present invention.

FIG. 23 is an overexcitation limiting diagram used in the tenth embodiment of the present invention.

FIG. 24 is a configuration diagram of an excitation control device showing a modification of the tenth embodiment of FIG. 21;

FIG. 25 is a configuration diagram of an excitation control device showing an eleventh embodiment of the present invention.

FIG. 26 is a configuration diagram of an excitation control device showing a twelfth embodiment of the present invention.

FIG. 27 is a configuration diagram of an excitation control device showing a thirteenth embodiment of the present invention.

FIG. 28 is a configuration diagram of an excitation control device showing a fourteenth embodiment of the present invention.

FIG. 29 is a configuration diagram of an excitation control device showing a fifteenth embodiment of the present invention.

FIG. 30 is a configuration diagram of an excitation control device showing a sixteenth embodiment of the present invention.

FIG. 31 is a configuration diagram of an excitation control device showing a modification of the sixteenth embodiment of FIG. 30;

FIG. 32 is a configuration diagram of an excitation control device according to a seventeenth embodiment of the present invention.

FIG. 33 is a configuration diagram of an excitation control device showing a modification of the seventeenth embodiment of FIG. 32;

FIG. 34 is a configuration diagram of an excitation control device showing a conventional technique.

FIG. 35 is an overexcitation limit diagram of the prior art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Synchronous machine 2 Field winding 3 Main transformer 4 Circuit breaker for system parallelism 5 Power system 6 Thyristor rectifier 7 Field circuit breaker 8 Exciting power supply transformer 9A Inverter automatic voltage regulator 9B Inverter automatic voltage regulator 10A ( 10B) Control device 11A (11B) Fuse 12A (12B) Instrument transformer 13A (13B) Voltage setting device 14A (14B) Overexcitation limiting device 15A (15B) Instrument current transformer 16A (16B) First stage overexcitation Limiting device 17A (17B) Second stage overexcitation limiting device 18A (18B) Third stage overexcitation limiting device 19A (19B) Control signal calculator 20A (20B) Overexcitation limiting control detector 21A (21B) Overexcitation limiting control Signal selector 22A (22B) Phase adjustment circuit 24A (24B) Instrument current transformer 25A (25B) Power converter 27A (27B) Power signal performance Unit 29A (29B) First stage function generator 30A (30B) Second stage function generator 31A (31B) Third stage function generator 32A (32B) First stage power detection overexcitation limiter 33A (33B) Second Stage power detection over-excitation limiter 34A (34B) Third stage power detection over-excitation limiter 35A (35B) Power detection over-excitation limit control detector 36A (36B) Power detection over-excitation limit control signal selector 38A (38B, 39A) , 39B) Overexcitation limiting device 40A (40B) Low value selection circuit 41A (41B) Field voltage detector 43A (43B) Voltage detection overexcitation limiting device 44A (44B) Time setting device 45A (45B) Control input change rate detection Unit 46A (46B) Change rate judgment unit 50A (50B) Change rate detection overexcitation limit control signal selector 52A (52B) Overexcitation limit control state information transmission means 60A (60B) Gain calculation function generator 61A (61B) Setter 62A (62B) Gain calculation calculator 63A (63B) Power detection over-excitation limiting device 64A (64B) Excitation state determination information transmission means 65A (65B) Excitation state monitoring means 100 Overexcitation limit pullback value 101 Overexcitation limit detection start set value 102 Overexcitation limit line 103 Standby system switching restriction line 104 First stage overexcitation restriction line 105 Second stage overexcitation restriction line 106 Third stage overload Excitation limit line 108 Generator core end heating limit curve 109 Generator rated constant curve 110 Generator over-excitation limit curve 111 First stage power detection over-excitation limit line 112 Second stage power detection over-excitation limit line 113 Third Stage power detection over-excitation limit line 114 over-excitation limit line 115 over-excitation limit line 116 over-excitation limit voltage pullback value 117 over-excitation Limiting the detection start voltage set value 118 voltage detection overexcitation limit line 119 voltage detection standby switching limit line 120 change rate detecting overexcitation limit line 121 change rate detecting overexcitation limit line 122 change rate detecting overexcitation limit line

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Norio Osugi 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant, Inc. (72) Inventor Toshiaki Sogabe 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Fuchu Plant, Toshiba Terms (reference) 5H590 AA02 AA21 AB06 CC01 CE01 DD24 DD64 DD70 DD77 EA07 EB02 EB21 EB29 FA06 FB05 FC15 GA02 GA03 GA05 GA07 HA01 HA02 HA03 HA04 HA05 HA06 HA07 HA10 HB02 HB03 JA08 JA09 JA14 JB11

Claims (16)

[Claims] A synchronous machine connected to a power system outputs an excitation control signal for performing excitation control of a synchronous machine so as to generate a predetermined voltage, and detects an overexcitation state of the synchronous machine with a time limit characteristic. An automatic voltage adjusting device for adding and outputting an overexcitation limit signal for limiting to a predetermined overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state to a field. In the excitation control device that performs the excitation control of the above, a plurality of overexcitation limiting lines that sequentially and sequentially defines the overexcitation of the reverse time limit characteristic with respect to the field current or the field voltage and the field current signal of the synchronous machine or The field voltage signal is compared with each overexcitation limit line for each overexcitation limit line, and the field current signal or the field voltage signal of the synchronous machine is individually provided for each overexcitation limit line that is equal to or greater than the overexcitation limit line. Apply individual overexcitation limit signal Means for limiting the current over-excitation state from the current over-excitation state to the predetermined over-excitation limit withdrawal value and outputting the obtained signal, and adding the individual over-excitation restriction signals output by the means. Means for adding and outputting an overexcitation limiting signal to the excitation control signal. 2. A synchronous machine connected to a power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an overexcitation state of the synchronous machine with a time limit characteristic. An automatic voltage adjusting device for adding and outputting an overexcitation limit signal for limiting to a predetermined overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state to a field. In the excitation control device that performs the excitation control of the above, a plurality of overexcitation limit lines that sequentially and sequentially determines the limit of the overexcitation state of the time limit characteristic with respect to the field current or the field voltage and the field current signal of the synchronous machine or When comparing with the field voltage signal and detecting that the field current signal or the field voltage signal of the synchronous machine has exceeded any of the overexcitation limit lines, the overexcitation limit line in the most overexcitation state is specified, Overexcitation limit specified Means for setting and outputting an overexcitation limiting signal provided so that it can be limited from the current overexcitation state to the predetermined overexcitation limit pullback value by the overexcitation limit signal; and the specified most overexcitation state. Means for selecting an over-excitation limiting signal corresponding to the over-excitation limiting line and outputting the added signal to the excitation control signal. 3. A synchronous machine connected to an electric power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an over-excitation state of the synchronous machine and outputs a predetermined signal. An automatic voltage adjustment device that additionally outputs an overexcitation suppression signal for limiting to an overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state and set the field to be a weak field. An excitation control device that detects active power and reactive power output from the synchronous machine,
Based on the detected active power signal and a predetermined coefficient,
Create multiple over-excitation limit lines that determine the over-excitation limit for the reactive power in a stepwise manner, compare it with the created over-excitation limit line, and find that the reactive power signal of the synchronous machine exceeds the over-excitation limit line. Means for determining and outputting the current over-excitation state from the current over-excitation state to the predetermined over-excitation limit withdrawal value by a signal obtained by adding the individual over-excitation restriction signals individually provided for each over-excitation restriction line, Means for adding and outputting the overexcitation limiting signal obtained by adding each overexcitation limiting signal outputted by this means to the excitation control signal. 4. A synchronous machine connected to an electric power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an over-excitation state of the synchronous machine and outputs a predetermined signal. An automatic voltage adjustment device for adding and outputting an overexcitation limit signal for limiting to an overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state and make the overexcitation state a field. The active power and the reactive power of the synchronous machine are detected, and a plurality of over-excitation limits for the reactive power are determined in a stepwise manner based on the detected active power signal and a predetermined coefficient. Create excitation limit lines, compare them with each created overexcitation limit line,
If the reactive power signal of the synchronous machine is detected as any of the overexcitation limit lines, the overexcitation limit line for the most overexcitation state is specified, and the overexcitation limit signal provided for the specified overexcitation limit line is output. Means for determining and outputting from the current over-excitation state to the predetermined over-excitation limit withdrawal value by the over-excitation limit signal, and an output corresponding to the specified over-excitation limit line in the specified over-excitation state. Means for selecting an excitation limiting signal and additionally outputting the selected signal to the excitation control signal. 5. The thyristor of the phase adjusting means additionally outputs a signal so that the firing phase angle of the thyristor based on the over-excitation limiting signal is weakened with respect to the firing phase angle of the thyristor based on the excitation control signal. 5. The excitation control apparatus according to claim 1, wherein an overexcitation state of the synchronous machine is suppressed by shifting an arc phase angle. 6. A synchronous machine connected to an electric power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an overexcitation state of the synchronous machine with a time limit characteristic. An automatic voltage adjusting device for adding and outputting an overexcitation limit signal for limiting to a predetermined overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state to a field. In the excitation control device for controlling the excitation of the thyristor, the over-excitation of the time limit characteristic with respect to the field current or the field voltage is set so that the maximum operation can be performed within the operation range corresponding to the thyristor rectifier's capability. Means for comparing the over-excitation limit line of the synchronous machine with the field current signal or the field voltage signal of the synchronous machine, and comparing the field current signal or the field voltage signal of the synchronous machine with a plurality of over-excitation limit lines of If any of the over-excitation limit lines is reached, the over-excitation limit line in the lowest over-excitation state is specified, and an over-excitation limit signal provided for the specified over-excitation limit line is generated by the over-excitation limit signal. Means for determining and outputting a signal that can be limited from the excitation state to the predetermined overexcitation limit withdrawal value; and selecting an overexcitation limit signal output by the lowest overexcitation limit line and adding an output to the excitation control signal. An excitation control device comprising: 7. A synchronous machine connected to a power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an over-excitation state of the synchronous machine with a time limit characteristic. An automatic voltage adjusting device for adding and outputting an overexcitation limit signal for limiting to a predetermined overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state to a field. The excitation control device controls the excitation of the synchronous machine by comparing the field current signal of the synchronous machine with a first overexcitation limit line that defines at least one overexcitation limit of the time limit characteristic with respect to the field current. Means for outputting a first individual over-excitation limiting signal when the field current signal is equal to or greater than the first over-excitation limiting line; and a second determining one or more over-excitation limitations of the time limit characteristic with respect to the field voltage. The field voltage signal of the synchronous machine is Means for outputting a second individual overexcitation limit signal in the case of the second overexcitation limit line or more, an addition obtained by adding the first individual overexcitation limit signal and the second individual overexcitation limit signal. An excitation control device, characterized in that the signal is a means for adding and outputting a signal to the excitation control signal. 8. A synchronous machine connected to a power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an overexcitation state of the synchronous machine with a time limit characteristic. An automatic voltage adjusting device for adding and outputting an overexcitation limit signal for limiting to a predetermined overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state to a field. In the excitation control device that controls the excitation of the motor, one or more over-excitation limit lines that sequentially determine the over-excitation limit of the time limit characteristic with respect to the field current and the field current signal of the synchronous machine are over-excited. When the field current signal of the synchronous machine is equal to or greater than the over-excitation limit line, the current over-excitation is performed by adding the first individual over-excitation limit signal individually provided for each over-excitation limit line. Output to determine the state can be limited Means for detecting active power and reactive power of the synchronous machine, and based on the detected active power signal and a predetermined coefficient, one or more over-excitation limiting lines that define over-excitation for the reactive power. Create and compare with each created over-excitation limit line, if the reactive power signal of the synchronous machine is more than the over-excitation limit line, each second individual over-excitation suppression signal provided separately for each over-excitation limit line Means for determining and outputting the current overexcitation state so that it can be limited by the added signal; and adding each first individual overexcitation restriction signal and each second individual overexcitation restriction signal output by this means. Means for adding and outputting a signal obtained as a result to the overexcitation suppression signal. 9. A synchronous machine connected to an electric power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an overexcitation state of the synchronous machine with a time limit characteristic. An automatic voltage adjusting device for adding and outputting an overexcitation limit signal for limiting to a predetermined overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state to a field. A plurality of over-excitation limit lines that sequentially determine the over-excitation limit of the time limit characteristic with respect to the field current or the field voltage and the field current signal of the synchronous machine or the field Means for comparing the magnetic field signal with the magnetic field signal and outputting each overexcitation limiting signal corresponding to the overexcitation limiting line when the field current signal or the field voltage signal of the synchronous machine exceeds the overexcitation limiting line. And the field current signal of the synchronous machine Alternatively, a change rate of the field voltage signal is calculated, and one of the plurality of overexcitation limit lines is selected according to the calculated change rate, and an overexcitation limit signal corresponding to the selected overexcitation limit line is generated. Means for adding and outputting the excitation control signal. 10. A synchronous machine connected to an electric power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an overexcitation state of the synchronous machine with a time limit characteristic. An automatic voltage adjusting device for adding and outputting an overexcitation limit signal for limiting to a predetermined overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state to a field. In the excitation control device that performs the excitation control of, the reactive power signal of the synchronous machine is compared with a plurality of over-excitation limit lines that determine the over-excitation limit of the reverse time characteristic with respect to the reactive power by sequentially calculating the limit. When the reactive power signal of the synchronous machine exceeds the overexcitation limit line, a means for outputting each overexcitation limit signal corresponding to the overexcitation limit line, and calculating the rate of change of the reactive power signal of the synchronous machine. , According to the calculated rate of change By selecting one of a plurality of overexcitation limit line, excitation control device, characterized in that the overexcitation limit signal corresponding to the overexcitation limit line selected and means for adding output to the excitation control signal. 11. A synchronous machine connected to a power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an over-excitation state of the synchronous machine with a time limit characteristic. An automatic voltage adjusting device for adding and outputting an overexcitation limit signal for limiting to a predetermined overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state to a field. In the excitation control device that performs the excitation control of, the field voltage or one or more overexcitation limit lines that sequentially and sequentially defines the overexcitation limit of the time limit characteristic with respect to the field voltage and the field current signal of the synchronous machine or Compare with the field voltage signal,
Means for outputting an individual overexcitation limit signal in accordance with each overexcitation limit line when the field current signal or the field voltage signal of the synchronous machine is equal to or greater than the overexcitation limit line; Means for calculating the control gain according to the magnetic voltage signal, the means corresponding to the one or more over-excitation limiting lines, and the individual over-excitation limiting signals based on the control gains corresponding to the individual over-excitation limiting signals. Means for adding and outputting an addition signal of the signal obtained by increasing or decreasing the excitation control signal to the excitation control signal. 12. A means corresponding to one or more over-excitation limit lines for calculating the control gain includes a synchronous machine field current setting signal or a field voltage setting signal which can be set from the outside and a synchronous machine field current. The excitation control device according to claim 11, wherein the control gain is calculated according to a signal or a deviation signal from a field voltage signal. 13. A synchronous machine connected to a power system outputs an excitation control signal for performing excitation control of the synchronous machine so as to generate a predetermined voltage, and detects an overexcitation state of the synchronous machine with a time limit characteristic. An automatic voltage adjusting device for adding and outputting an overexcitation limit signal for limiting to a predetermined overexcitation limit pullback value to the excitation control signal so as to weaken the overexcitation state to a field. An excitation control device that controls the excitation of the synchronous machine by comparing one or more overexcitation limit lines, which sequentially define the overexcitation of the reactive time characteristic with respect to the reactive power in a stepwise manner, with the reactive power signal of the synchronous machine. Means for outputting an individual overexcitation suppression signal in accordance with each overexcitation limit line when the reactive power signal is equal to or greater than the overexcitation limit line, and calculating the control gain in accordance with the reactive power signal of the synchronous machine. Corresponding to the overexcitation limit line Means, and a means for adding and outputting an addition signal of a signal obtained by increasing or decreasing each of the individual overexcitation limiting signals based on each of the individual overexcitation limiting signals and the control gain corresponding to the excitation control signal. An excitation control device, comprising: 14. A unit corresponding to one or more over-excitation limit lines for calculating the control gain, according to a deviation signal between an externally settable reactive power setting signal of the synchronous machine and a reactive power signal of the synchronous machine. 14. The excitation control device according to claim 13, wherein the control gain is calculated. 15. A control means for outputting an excitation control signal for performing excitation control of the synchronous machine so that the synchronous machine connected to the electric power system generates a predetermined voltage, and an over-excitation state of the synchronous machine is set to a time limit characteristic. Over-excitation limiting means for adding and outputting to the excitation control signal an over-excitation limiting signal for detecting and limiting the over-excitation limit to a predetermined over-excitation return value so as to weaken the over-excitation state to a field. In an excitation control device having an automatic voltage adjustment device having a redundant configuration with a standby system and performing excitation control of a synchronous machine, the automatic voltage adjustment device of each own system has an overvoltage of its own system when its own system is a normal system. An excitation control device comprising means for transmitting overexcitation state information including an overexcitation restriction signal from the excitation restriction means to overexcitation restriction means of another system. 16. A control means for outputting an excitation control signal for performing excitation control of the synchronous machine so that the synchronous machine connected to the power system generates a predetermined voltage, and an over-excitation state of the synchronous machine is set to a time limit characteristic. Over-excitation limiting means for adding and outputting to the excitation control signal an over-excitation limiting signal for detecting and limiting the over-excitation limit to a predetermined over-excitation return value so as to weaken the over-excitation state to a field. In an excitation control device having an automatic voltage adjustment device having a dual configuration with a standby system and performing excitation control of a synchronous machine, the automatic voltage adjustment device of each own system detects its own system when its own system is a regular system. Means for transmitting the field current signal or field voltage signal of the synchronous machine and the phase signal output from the control means of each system to the excitation state monitoring means of the standby system of another system, and when the own system is a standby system The excitation state monitoring means. Means for monitoring the correlation between the state of the phase signal of the service system and the field current signal or the field voltage signal, and switching the self system to the service system according to predetermined conditions. Excitation control device.