JP4679418B2 - Field current control system - Google Patents

Description

  The present invention relates to a field current control system, and is particularly useful when applied to a static AVR (Automatic Voltage Regulator) type excitation device.

  FIG. 5 is a block diagram showing a field current control system according to the prior art applied to a static AVR exciter. As shown in the figure, the generator 1 adjusts the system voltage applied to the bus 3 with the field current supplied to the field winding 2. For this reason, it has a control means I comprising a detection unit 4, a setting device 5, an amplification / control unit 6 and a detection unit 7. By controlling the output voltage of the rectifier 8 by this control means I, The current is adjusted. Here, the rectifier 8 is supplied with electric power via an excitation transformer 9 connected to the bus 3. That is, the rectifier 8 uses an AC voltage, which is a system voltage, as a power supply, and rectifies it to convert it into a DC voltage. In addition, the thick line in a figure has each shown that it is an electric power system, and a thin line is a control system.

Such a field current control system operates as follows.
1) The detection unit 4 detects the system voltage and current via PT and CT and transmits them to the setter 5.
2) The setter 5 is set with a target value of the terminal voltage (system voltage) of the generator 1, detects a difference from the voltage obtained from the detector 4 and amplifies / controls this information 6 Transmit to.
3) The detection unit 4 detects the voltage or current of the field circuit via the voltmeter 10 and the ammeter 11 and transmits this information to the amplification / control unit 6.
4) The amplification / control unit 6 controls the excitation current supplied to the field winding 2 based on the information from the setting unit 5 and the detection unit 7 so that the terminal voltage of the generator 1 becomes a target value. Is transmitted to the rectifier 8.
5) The rectifier 8 rectifies the alternating current connected to the system via the excitation transformer 9 and converts it into direct current. At this time, control is performed so that a field current having a value commanded from the amplification / control unit 6 is supplied to the field winding 2.
6) By the above operation, even when the terminal voltage of the generator 1 fluctuates due to disturbance or the like, the target voltage is quickly controlled.

  Technologies for improving the system transient stability with respect to the excitation system of the generator are intended to enhance the excitation control system (see Patent Document 1), and are intended to modify the field winding (see Patent Document 2). A device provided with a control circuit that cancels fluctuations in the system voltage (see Patent Documents 3 and 4) is known.

JP 2004-48915 A JP 2003-324995 A Japanese Patent Laid-Open No. 10-80199 JP-A-10-164899

  In the field current control system shown in FIG. 5, as a result of using the system voltage as a power source, when the system voltage fluctuates due to a large disturbance or the like, the power source voltage of the rectifier 8 that is the secondary voltage of the excitation transformer 9 fluctuates. The fluctuation of the system voltage caused the field current to fluctuate, and the transient stability was impaired.

  By the way, the self-excited exciter currently used in many generators generally obtains DC power from the rectifier connected to the power plant bus and uses it as the power source of the exciter. Regardless of the line method, fluctuations in the system voltage cause the field current to fluctuate and cause transient stability to be impaired. In fact, the above-mentioned Patent Documents 3 and 4 are techniques for suppressing the influence of fluctuations in the system voltage by the control circuit. However, since the system is the only power source, it cannot cope with large fluctuations in the system voltage and control delays. The influence on the excitation circuit cannot be completely eliminated due to factors such as the presence of.

  An object of the present invention is to provide a field current control system that can eliminate the influence of a large disturbance that occurs in the event of a system fault or the like and obtain good transient stability.

The first aspect of the present invention for achieving the above object is as follows:
Voltage compensation means for adjusting the voltage so that the output becomes a constant AC voltage based on the system voltage that is the terminal voltage of the generator;
The field current control system includes a rectifier that operates with the voltage compensation unit as an AC power source and controls a field current supplied to the field winding of the generator so that the system voltage is constant. And
The voltage compensation means includes a power storage device, an AC / DC converter that converts a DC voltage that is an output of the power storage device into a constant AC voltage, and a high-speed that cuts off a current based on the system voltage when a large disturbance occurs. A circuit breaker, and the AC / DC converter and the high-speed circuit breaker are connected to each output side to output a constant AC voltage from the output side. Is a field current control system.

According to this aspect, the voltage of the system greatly fluctuates due to disturbance or the like , and even if the input voltage of the voltage compensation means fluctuates greatly, the output voltage is always adjusted to a constant AC voltage. It becomes constant. Therefore, the rectifying means can always continuously supply a field current with a constant system voltage to the field winding of the generator. That is, it is possible to eliminate the influence of large fluctuations due to system voltage disturbances and the like. For this reason, more appropriate field control is possible, and transient stability can be improved. In addition, when the occurrence of disturbance is detected, the high-speed circuit breaker is quickly operated to disconnect the system voltage, and a constant AC voltage formed based on the output voltage of the power storage device can be input to the rectifying means. .

  As a result, the AC voltage that is always adjusted to be constant is input to the rectifying means, and the influence of the large fluctuation of the system voltage on the field current can be eliminated. At this time, it is not necessary to detect the occurrence of disturbance or the like. This is because the input voltage of the control means for controlling the field current is not affected even if a disturbance or the like occurs.

The second aspect of the present invention is:
In the field current control system described in the first aspect ,
In the field current control system, the power storage device is charged using a DC output of the AC / DC converter.

  According to this aspect, by making the AC / DC converter function as a charging device, it is possible to perform necessary charging of the power storage device. As a result, the input voltage of the rectifying means can always be kept stable and constant.

The third aspect of the present invention is:
In the field current control system described in the first aspect ,
A field current control system is characterized in that the power storage device is charged using a charging means provided separately.

  According to this aspect, the necessary charging of the power storage device can be performed by an independent charging unit driven by a separately provided power source. As a result, it is possible to stabilize the input voltage of the rectifying means even better than in the case of the fifth aspect.

  According to the present invention as described above, since the AC input voltage of the rectifying means can be maintained constant by the voltage compensating means for inputting the system voltage and adjusting the voltage, the system voltage relative to the field current of the generator can be maintained. The influence of fluctuation can be eliminated, more appropriate field control can be performed, and transient stability can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a field current control system according to an embodiment of the present invention. As shown in the figure, the field current control system according to this embodiment is obtained by adding a voltage compensation device 12 to the field current control system according to the prior art shown in FIG. Many other configurations are the same as those in the field current control system shown in FIG. 5, and therefore, the same parts are denoted by the same reference numerals and redundant description is omitted.

As shown in FIG. 1, the voltage compensator 12 takes in the system voltage that is the terminal voltage of the generator 1 through the excitation transformer 9 and adjusts the output to be a constant AC voltage V _0. An alternating voltage V ₀ is supplied to the rectifier 8 as an input voltage. The rectifier 8 performs a predetermined rectification operation using the AC voltage V ₀ that is always maintained constant by the voltage compensator 12 as an AC power supply, and the generator 1 so that the system voltage becomes constant according to a command from the amplification / control unit 6. The field current supplied to the field winding 2 is controlled.

According to this embodiment, the voltage of the system greatly fluctuates due to disturbance or the like, and even if the input voltage of the voltage compensator 12 fluctuates greatly, the output voltage is always adjusted to the constant AC voltage V _0. The input voltage of 8 is constant. Therefore, the rectifier 8 can always continuously supply a field current with a constant system voltage to the field winding 2 of the generator 1.

  Various specific configurations of the voltage compensator 12 can be considered, and three preferred embodiments among them will be described.

<First embodiment>
FIG. 2 is a block diagram showing the voltage compensator according to the first embodiment. As shown in the figure, the voltage compensator 12 according to this embodiment includes an AC / DC converter 13, a power storage device 14, and an AC / DC converter 15. Here, the AC / DC converter 13 converts an AC voltage, which is an output voltage of the excitation transformer 9 based on the system voltage, into a DC voltage. The power storage device 14 is connected in parallel with the AC / DC converter 13 and outputs a DC voltage V ₁ adjusted to a constant value as an output voltage of both. The AC / DC converter 15 outputs a constant AC voltage V ₀ by converting the DC voltage V ₁ into an AC voltage as an input voltage. In other words, the AC / DC converter 15 is always driven with the constant DC voltage V ₁ as an input voltage and outputs a constant AC voltage V ₀ . Therefore, the AC voltage V ₀ that is the output voltage of the AC / DC converter 15 and the input voltage of the rectifier 8 is always a constant value.

According to the present embodiment, even if the system voltage fluctuates greatly and the DC output voltage of the AC / DC converter 13 is about to change, this change in DC voltage is suppressed by the output voltage of the power storage device 14 and input to the AC / DC converter 15. that the DC voltages V ₁ is always a constant value. Based on this, the AC / DC converter 15 outputs a constant AC voltage V ₀ .

As a result, the rectifier 8 can perform a stable rectification operation based only on the control command of the amplification / control unit 6 with the AC voltage V ₀ maintained constant as the input voltage. As a result, it is possible to stably control the field current to a predetermined value by removing the influence of the large fluctuation of the system voltage on the field current. At this time, it is not necessary to detect the occurrence of disturbance or the like. This is because even if a disturbance or the like occurs, the input voltage of the rectifier 8 that controls the field current is not affected.

  The power storage device 14 is charged as required by the output of the AC / DC converter 13.

<Second embodiment>
FIG. 3 is a block diagram showing a voltage compensator according to the second embodiment. As shown in the figure, the voltage compensation device 12 according to this embodiment includes a high-speed circuit breaker 16, an AC / DC converter 17, and a power storage device 18. Here, the high-speed circuit breaker 16 interrupts the current based on the system voltage when a large disturbance occurs, in other words, separates the excitation transformer 9 from the voltage compensation device 12. On the other hand, the AC / DC converter 17 converts the DC voltage that is the output of the power storage device 18 into a constant AC voltage V ₀ . Here, the output side of the AC / DC converter 17 is connected to the output side of the high-speed circuit breaker 16, and a constant AC voltage V ₀ is output from this output side.

According to the present embodiment, a constant AC voltage V ₀ that is an output voltage of the excitation transformer 9 is supplied to the rectifier 8 through the high-speed circuit breaker 16 at normal times. On the other hand, when the occurrence of disturbance is detected, the high-speed circuit breaker 16 is promptly operated to disconnect the system voltage, and the rectifier 8 is provided with the constant voltage formed by the AC / DC converter 17 based on the output voltage of the power storage device 18. to enter the AC voltage _{V 0.}

As a result, the rectifier 8 is always supplied with the AC voltage V ₀ adjusted to be constant, and the influence of the large fluctuation of the system voltage on the field current can be eliminated.

  The power storage device 18 is charged as required by the output of the AC / DC converter 17.

<Third embodiment>
FIG. 4 is a block diagram showing a voltage compensator according to the third embodiment. As shown in the figure, the voltage compensation device 12 according to this embodiment includes a series transformer 19, an AC / DC converter 20, a power storage device 21, and a control unit 22. Here, the secondary side of the excitation transformer 9 corresponding to the system voltage is connected to the input side of the primary side winding of the series transformer 19, and the output side of the primary side winding of the series transformer 19 is The output AC voltage V ₀ is applied to the input side of the rectifier 8.

The AC / DC converter 20 converts the DC voltage, which is the output of the power storage device 21, into an AC voltage and applies it to the secondary winding of the series transformer 19. Here, a voltmeter 23 is disposed on the input side of the series transformer 19, and the voltmeter 23 detects the AC voltage V ₂ on the input side. The control unit 22 compares the voltage information detected by the voltmeter 23 with a preset set voltage value, and outputs the output voltage V ₃ corresponding to the difference between the two to the AC / DC converter 20. To control. Here, the set voltage value is set in correspondence with the AC voltage V ₀ which is the output of the voltage compensator 12. As a result, when the voltage of the input side of the series transformer 19 is varied, the output voltage V ₃ of the AC-DC converter 20 so as to suppress the variation is applied to the secondary winding of the series transformer 19 A corresponding voltage is superimposed on the primary winding.

According to the present embodiment, to complement the input change of the AC voltage V ₂ of the series transformer 19 based on the system voltage, the output voltage V of the AC-DC converter 20 that is adjusted based on the output voltage of the power storage device 21 ₃ is superimposed on the primary winding to make the AC voltage V ₀ that is the output of the series transformer 19 constant.

As a result, the rectifier 8 is always supplied with the AC voltage V ₀ adjusted to be constant, and the influence of the large fluctuation of the system voltage on the field current can be removed. At this time, it is not necessary to detect the occurrence of disturbance or the like. This is because the AC voltage V ₀ that is the input of the rectifier 8 that controls the field current is not affected even if a disturbance or the like occurs.

<Other embodiments>
The power storage devices 14, 18, and 21 in each of the embodiments described above can be most commonly configured with a battery, but are not limited thereto. For example, a capacitor, particularly an electric double layer capacitor can be preferably configured. In the case of a capacitor, power for driving is not required, which is also preferable in this respect.

  The power storage devices 14, 18, and 21 may be charged using a charging device connected to an external power source.

  The present invention can be used in an industrial field in which power supply or maintenance of a power supply system is performed.

It is a block diagram which shows the control system of the field current which concerns on embodiment of this invention. It is a block diagram which shows the 1st Example of the voltage compensation apparatus in FIG. It is a block diagram which shows the 2nd Example of the voltage compensation apparatus in FIG. FIG. 4 is a block diagram showing a third embodiment of the voltage compensation device in FIG. 1. It is a block diagram which shows the control system of the field current based on a prior art.

Explanation of symbols

I control means 1 generator 2 field winding 3 bus 8 rectifier 10 voltmeter 11 ammeter 12 voltage compensator 13, 15, 17, 20 AC / DC converters 14, 18, 21 power storage device 16 high speed circuit breaker 19 in series Transformer

Claims (3)

Voltage compensation means for adjusting the voltage so that the output becomes a constant AC voltage based on the system voltage that is the terminal voltage of the generator;
The field current control system includes a rectifier that operates with the voltage compensation unit as an AC power source and controls a field current supplied to the field winding of the generator so that the system voltage is constant. And
The voltage compensation means includes a power storage device, an AC / DC converter that converts a DC voltage that is an output of the power storage device into a constant AC voltage, and a high-speed that cuts off a current based on the system voltage when a large disturbance occurs. A circuit breaker, and the AC / DC converter and the high-speed circuit breaker are connected to each output side to output a constant AC voltage from the output side. A field current control system. The field current control system according to claim 1 ,
A field current control system characterized in that charging of the power storage device is performed using a DC output of the AC / DC converter. The field current control system according to claim 1 ,
A field current control system characterized in that charging of the power storage device is performed using a charging means provided separately.

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