JP4889355B2 - 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. 3 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 section 4, a setting device 5, an amplification / control section 6 and a detection section 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 system voltage and current are detected by the detection unit 4 via PT and CT and transmitted to the setting device 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 detection unit 4, and amplifies / controls this information. 6 is transmitted.
3) The detection unit 7 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 system transient stability with respect to the generator excitation system are to improve the excitation control system (Patent Document 1), to improve the field winding (Patent Document 2), system voltage (Patent Literature 3, Patent Literature 4) and the like provided with a control circuit that cancels the fluctuations are 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. 3, as a result of using the system voltage as a power source, if 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 varies. 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 a power source for 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, Patent Documents 3 and 4 described above 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:
Rectifying means that operates with the system voltage, which is the terminal voltage of the generator, as an AC power supply,
Power storage means connected in parallel to the output side of the rectification means and functioning as a direct current power source; connected between the output side of the rectification means and power storage means and the field winding of the generator; Voltage adjusting means for converting the output voltage of the means and the power storage means into a predetermined DC voltage;
The field winding is controlled by controlling the rectifying means so that a DC voltage on the output side of the rectifying means and the power storage means becomes a constant voltage, and controlling the output voltage of the voltage adjusting means based on the constant voltage. And a control means for controlling the voltage adjusting means so that the system voltage becomes a constant voltage by controlling a field current supplied to the field current .

  According to this aspect, even if the system voltage fluctuates greatly due to disturbance or the like, and the input voltage of the rectifying means fluctuates greatly, the fluctuation is suppressed by the power storage device. As a result, the input voltage of the voltage adjusting means is kept constant. Therefore, the voltage adjusting means can keep supplying a field current that is always stable and the system voltage becomes constant to the field winding of the generator. That is, the field current is not affected by the system voltage. For this reason, more appropriate field control is possible, and transient stability can be improved. At this time, it is not necessary to detect the occurrence of disturbance or the like. This is because the input voltage of the voltage adjusting 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 the rectifier.

  According to this aspect, the required charge of the power storage device can be performed by causing the rectifying means to function as a charging device. As a result, the input voltage of the power adjustment device 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,
The field current control system is characterized in that the power storage device is separately charged using a charging means independent of the rectifying means.

  According to this aspect, the necessary charging of the power storage device can be performed by the charging means independent of the rectifying means. As a result, it is possible to stabilize the input voltage of the power adjustment apparatus even better than in the case of the second aspect.

  According to the present invention as described above, the influence of the fluctuation of the system voltage on the field current of the generator can be eliminated by maintaining the input voltage of the voltage adjusting means constant, thereby enabling more appropriate field control. 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 a first embodiment of the present invention. As shown in the figure, the field current control system according to the present embodiment is obtained by adding a voltage regulator 13 and a power storage 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.

  As shown in FIG. 1, the power storage device 12 functions as a DC power source and is connected in parallel to the output side of the rectifier 8. The voltage regulator 13 is connected between the output side of the rectifier 8 and the power storage device 12 and the field winding 2, and is a DC / DC that converts the output voltage of the rectifier 8 and the power storage device 12 into a predetermined DC voltage. It is a DC converter.

  The control means II controls the rectifier 8 so that the DC voltage on the output side of the rectifier 8 and the power storage device 12 becomes a constant voltage, and the voltage of the bus 3 via the field current supplied to the field winding 2. The voltage regulator 13 is controlled so that the system voltage is a constant voltage.

  More specifically, the value of the DC voltage, which is the output voltage of the rectifier 8 and the power storage device 12, is supplied to the detector 17 of the control means II via the voltmeter 14 connected to the output side of both, and the voltage value Is detected. The voltage information based on the voltage value is supplied from the detection unit 17 to the amplification / control unit 16 together with the field circuit voltage and current information detected via the voltmeter 10 and the ammeter 11. The amplification / control unit 16 controls the rectifier 8 based on the output voltage information of the rectifier 8 and the power storage device 12 so that the output voltage becomes a preset constant value. At this time, the rectifier 8 also charges the power storage device 12 as necessary to keep the output voltages of both constant. That is, it also functions as a charging device for the power storage device 12.

  On the other hand, the voltage regulator 13 is supplied with a field current control command from the amplification / control unit 16. That is, the rectifier 8 controls the field current supplied to the field winding 2 via the voltage regulator 13 so that the system voltage of the bus 3 becomes constant according to the control command of the amplification / control unit 16. Here, since the input voltage of the voltage regulator 13 is kept constant, the field current can be controlled in good response to the field current control command from the amplification / control unit 16.

  According to this embodiment, the output voltage is maintained constant by the rectifier 8 at normal times, and the system voltage is controlled to be constant by the field current adjusted by the voltage regulator 13. During operation of the field current control system by such control, even if the system voltage fluctuates greatly due to disturbance or the like, and the input voltage of the rectifier 8 fluctuates greatly, the output voltage tends to fluctuate greatly. This variation is suppressed by the power storage device 12.

  As a result, the input voltage of the voltage regulator 13 is always kept constant even when disturbances occur. Therefore, without special detection of the occurrence of disturbance or the like, the voltage regulator 13 can continue to supply the field current 2 to the field winding 2 of the generator 1 so that the system voltage is always stable and constant. . Incidentally, even when the supply of power from the rectifier 8 is interrupted due to an accident or the like, the output voltage is maintained constant by the power storage device 12. That is, the field current is not affected by the system voltage, and more appropriate field control is possible.

  FIG. 2 is a block diagram showing a field current control system according to the second embodiment of the present invention. As shown in the figure, the field current control system according to this embodiment is obtained by adding a charging device 15 to the first embodiment shown in FIG. Therefore, the same parts as those in the field current control system shown in FIG.

  As shown in FIG. 2, the field current control system according to the present embodiment is configured such that the power storage device 12 is charged separately using a charging device 15 independent of the rectifying device 8. Here, the charging device 15 is connected to an external power source.

  According to this embodiment, the power storage device 12 can be charged by the charging device 15 independent of the rectifying device 8. As a result, the input voltage of the voltage regulator 13 can be stabilized more satisfactorily than in the case of the first embodiment.

  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 the 1st Embodiment of this invention. It is a block diagram which shows the control system of the field current which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the control system of the field current based on a prior art.

Explanation of symbols

II control means 1 generator 2 field winding 3 bus 8 rectifier 10 voltmeter 11 ammeter 12 power storage device 13 voltage regulator 14 voltmeter 15 charging device

Claims (3)

Rectifying means that operates with the system voltage, which is the terminal voltage of the generator, as an AC power supply,
Power storage means connected in parallel to the output side of the rectifying means and functioning as a DC power source;
Voltage adjusting means connected between the output side of the rectifying means and the power storage means and a field winding of the generator, and converting the output voltage of the rectifying means and the power storage means into a predetermined DC voltage;
The field winding is controlled by controlling the rectifying means so that a DC voltage on the output side of the rectifying means and the power storage means becomes a constant voltage, and controlling the output voltage of the voltage adjusting means based on the constant voltage. And a control means for controlling the voltage adjusting means so that the system voltage becomes a constant voltage by controlling a field current supplied to the field current . The field current control system according to claim 1,
A field current control system characterized in that the power storage device is charged using the rectifying means. The field current control system according to claim 1,
A field current control system characterized in that the power storage device is separately charged using a charging means independent of the rectifying means.

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