JP4757082B2 - 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.

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 for supplying a field current to the field winding of the generator;
Control means for controlling the rectifying means so that the system voltage becomes constant with a system voltage that is a terminal voltage of the generator as a power source;
The generator is switched when a large disturbance is detected, and is controlled by the control means to control the field current supplied to the field winding so that the system voltage becomes constant instead of the rectifying means. With other power supply means independent of the grid ,
The other power supply means has a power storage means and a voltage adjustment means, and normally charges the power storage means with the voltage adjustment means using the rectifying means as a power source as necessary, and after the switching, A field current control system configured to control a field current supplied to the field winding by using the power storage means as a power source so that the system voltage becomes constant by the voltage adjusting means. is there.

  According to the present invention as described above, the field current of the generator is not affected by the system voltage, so that more appropriate field control is possible 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 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 power supply means II 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.

  The power supply means II is switched when a large disturbance is detected, and controls the field current supplied to the field winding 2 so that the system voltage becomes constant instead of the rectifier 8. Here, the power supply means II includes a voltage regulator 12 and a power storage device 13 and constitutes another power source independent of the system of the generator 1.

  The voltage adjustment device 12 normally charges the power storage device 13 with electric power adjusted to a predetermined voltage using the rectifier 8 as a power source when necessary (when the charged amount becomes a predetermined value or less), and causes a large disturbance or the like When an abnormality occurs due to the occurrence, the field current supplied to the field winding 2 is controlled by using the power storage device 13 as a power source so that the system voltage of the bus 3 becomes constant. Here, the necessary control of the voltage regulator 12 and the power storage device 13 is performed by the output signal of the amplification / control unit 6. That is, switching of the rectifier 8 and the power storage device 13 or adjustment of the output voltage of the voltage regulator 12 is performed by the output signal. Here, the amplification / control unit 6 is supplied with a state signal indicating the state of the bus 3 such as a system voltage via the detection unit 4 and the setting device 5 and can detect a normal state or an abnormal state of the system. It is constituted as follows.

  The detection of the normal state or the abnormal state is not necessarily limited to the one in this example, and no special limitation is imposed including a known one.

  In this embodiment, at the normal time, the same control as in the prior art shown in FIG. 3 is performed.

  On the other hand, when the amplification / control unit 6 detects an abnormal state due to a large disturbance or the like, the amplification / control unit 6 issues a command to stop the supply of the field current to the rectifier 8. At the same time, a command to switch the power source to the power storage device 13 is issued, while a command to start the supply of the field current is given to the voltage regulator 12, and the value of the field current in this case is designated.

  Thereafter, the field current supplied to the field winding 2 is controlled by the voltage regulator 12 using the power storage device 13 as a power source so that the system voltage of the bus 3 becomes constant until the normal state is restored. More specifically, a command to stop the supply of field current to the voltage regulator 12 to return to the normal state when it is confirmed that the system voltage is stable after a lapse of a certain time from the occurrence of disturbance or the like. , And starts to supply the field current to the rectifier 8 and commands the current value in that case.

  Further, when the amount of power stored in the power storage device 13 decreases due to natural discharge or field current supply, the amplification / control unit 6 confirms that there is no disturbance or the like, and then checks the voltage storage device 12 with respect to the power storage device. Command 13 to start charging. At the same time, the rectifier 8 is instructed to energize the total power supplied to the voltage regulator 12 together with a predetermined field current. The amplification / control unit 6 commands the end of charging to the voltage regulator 12 when predetermined charging to the power storage device 13 is completed, and commands only the field current supply to the rectifier 8.

  If a disturbance or the like occurs during the charging period, the power supply by the rectifier 8 is immediately stopped, and the power supply means II is instructed to supply power.

  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 the present embodiment is obtained by changing the configuration of the power supply means II in the first embodiment shown in FIG. Therefore, the same parts as those in the field current control system shown in FIG.

  The power supply means III of this embodiment is also switched when a large disturbance is detected, and controls the field current supplied to the field winding 2 so that the system voltage becomes constant instead of the rectifier 8. Another power source independent of the system of the generator 1 is configured.

  Here, the power supply means III includes a voltage adjustment device 14, a power storage device 15, and a charging device 16 connected to an external power source. The charging device 16 charges the power storage device 15 and generates a disturbance. After the switching, the field current supplied to the field winding 2 is controlled by the voltage regulator 14 using the power storage device 15 as a power source so that the system voltage of the bus 3 is constant. That is, the other configuration is the same as that of the first embodiment shown in FIG. 1 except that the charging power of the power storage device 15 is obtained by the charging device 16 connected to an external power source.

  As a result, it is possible to obtain a unique effect that the charging operation is not disturbed by the field current, but other actions and effects can be considered as in 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

I Control means
II, III Electric power supply means 1 Generator 2 Field winding 3 Bus 8 Rectifier 10 Voltmeter 11 Ammeter 12, 14 Voltage regulator 13, 15 Power storage device 16 Charging device

Claims (1)

Rectifying means for supplying a field current to the field winding of the generator;
Control means for controlling the rectifying means so that the system voltage becomes constant with a system voltage that is a terminal voltage of the generator as a power source;
The generator is switched when a large disturbance is detected, and is controlled by the control means to control the field current supplied to the field winding so that the system voltage becomes constant instead of the rectifying means. With other power supply means independent of the grid ,
The other power supply means has a power storage means and a voltage adjustment means, and normally charges the power storage means with the voltage adjustment means using the rectifying means as a power source as necessary, and after the switching, A field current control system configured to control a field current supplied to the field winding by using the power storage means as a power source so that the system voltage becomes constant by the voltage adjusting means .

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