JP2010041880A - Excitation controller of self-excited ac generator in private power-generating facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably trip a load breaker when a short-circuit failure occurs while power is supplied to a load from a private power-generating facility. <P>SOLUTION: An excitation controller is equipped with: a feedback circuit 171 for feeding back an excitation current of an excitation machine 5 to the output of an automatic voltage controller 4; a first addition and subtraction means 45 which outputs a difference between the excitation current fed back by the feedback circuit 171 and the output of the automatic voltage controller 4; a current transformer 15 for excitation which inputs the output current of a generator 2 and outputs it via a rectification element 16; and a second addition and subtraction means 15ad which adds the output of the first addition and subtraction means 45 and the output of the current transformer 15 for excitation. By compensating a reduction of excitation current of the excitation machine 5 caused by a reduction in output of the automatic voltage controller 4 due to a short-circuit failure within a protection range by a protection relay 132 of a load 122 supplied with power from the generator 2, with the output of the current transformer 15 for excitation. The output voltage of the generator 2 is kept at nearly a predetermined value even during the short-circuit failure, to prevent the protection relay 132 from being disabled during the short-circuit failure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an excitation control device for a self-excited AC generator in a private power generation facility in which an output voltage is automatically adjusted to a predetermined voltage by an automatic voltage regulator.

  As shown in FIG. 8, the excitation control device for a self-excited AC generator in a conventional private power generation facility outputs the output of the excitation transformer 3 connected to the output end of the AC generator 2 that is rotationally driven by the driver 1. A DC output of an automatic voltage regulator (AVR) 4 serving as a power source is supplied to an exciter field winding 6 of a rotary exciter 5 directly connected to the AC generator 2 via a field breaker 7. The output of the exciter 5 is configured to be supplied to the generator field winding 9 of the AC generator 2 via the rectifier 8. The automatic voltage regulator 4 inputs the output voltage of the AC generator 2 via the instrument transformer 10 and supplies power to the exciter field winding 6 so that the output voltage of the AC generator 2 becomes a predetermined voltage. Control the amount. (See Patent Document 1)

  The loads 121 and 122 are fed from the AC generator 2 through the feeder line 11. For example, when a short circuit accident occurs on the load 122 side, the load 122 is protected from the short circuit current by tripping the load circuit breaker 142 by the operation of the overcurrent relay 132.

Japanese Patent Laid-Open No. 4-285458 (FIG. 5 and description thereof)

  In the excitation control device for a self-excited AC generator in the private power generation facility shown in FIG. 8, for example, when a short-circuit accident occurs on the load 122 side, the output voltage of the generator 2 is suddenly reduced, so that the automatic voltage regulator 4 As a result, the excitation current of the exciter excitation winding 6 fed from the automatic voltage regulator 4 also decreases abruptly, and the generator excitation winding 9 Since the exciting current of the generator also decreases rapidly, there is a possibility that the load breaker 142 will not trip due to insufficient operating current of the overcurrent relay 132. In this case, the output of the generator 2 rapidly decreases, and the load 121 also It becomes impossible to operate. Therefore, it is necessary to ensure that the corresponding load circuit breaker 142 is tripped when a short circuit accident occurs.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to ensure that a trip of a load circuit breaker is performed when a short-circuit accident occurs when power is supplied to a load by a private power generation facility. To do.

  The excitation control device for the self-excited AC generator in the private power generation facility according to the present invention takes the power from the output of the generator via the excitation transformer and converts it into the output voltage of the generator input via the instrument transformer. An automatic voltage regulator that responds and outputs an output based on a variable internal set value, a feedback circuit that feeds back an excitation current of the exciter of the generator to an output of the automatic voltage regulator, and the excitation that is fed back by the feedback circuit First addition / subtraction means for outputting the difference between the current and the output of the automatic voltage regulator, an excitation current transformer for inputting the output current of the generator and outputting it via a rectifying element, and the first addition / subtraction means And a second adder / subtracter that adds the output of the current transformer for excitation to a short-circuit accident that occurs in the protection range of the protection relay of the load fed from the generator The decrease in the excitation current of the exciter due to the decrease in the output of the automatic voltage regulator is compensated by the output of the excitation current transformer, and the output voltage of the generator is maintained at a substantially predetermined value even in the case of the short-circuit accident. This prevents the protective relay from malfunctioning during the short circuit.

  The present invention relates to an automatic voltage output from a generator output via an excitation transformer and output based on a variable internal set value in response to an output voltage of the generator input via an instrument transformer. A regulator, a feedback circuit that feeds back an excitation current of an exciter of the generator to an output of the automatic voltage regulator, and outputs a difference between the excitation current fed back by the feedback circuit and an output of the automatic voltage regulator First addition / subtraction means, an excitation current transformer that inputs the output current of the generator and outputs it via a rectifier element, and adds the output of the first addition / subtraction means and the output of the excitation current transformer. Excitation of the exciter due to a decrease in output of the automatic voltage regulator due to a short circuit accident caused by a short circuit accident caused by a protective relay of a load fed from the generator, comprising second addition / subtraction means The decrease in the current is compensated by the output of the current transformer for excitation, and the output voltage of the generator is maintained at a substantially predetermined value even in the case of the short circuit accident so as to prevent the protection relay from malfunctioning at the time of the short circuit. Therefore, there is an effect that the trip of the load circuit breaker is reliably performed when a short-circuit accident occurs when power is supplied to the load by the private power generation facility.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is a connection diagram showing an example of a private power generation facility and its power supply system, FIG. 2 is a block diagram illustrating the excitation control system of the excitation control device in FIG. 1 including the transfer functions of each part, and FIG. 3 is a function of FIG. It is a figure explaining operation | movement.

  In FIG. 1, the direct current output of an automatic voltage regulator (AVR) 4 that uses the output of an excitation transformer 3 connected to the output terminal of an alternating current generator 2 that is rotationally driven by a drive 1 as a power source is represented by an alternating current generator. 2 is supplied to an exciter field winding 6 of a rotary exciter 5 directly connected to 2 via a field breaker 7, and the output of the exciter 5 is supplied to a generator field of the AC generator 2 via a rectifier 8. It is configured to be supplied to the magnetic winding 9. The automatic voltage regulator 4 inputs the output voltage of the AC generator 2 via the instrument transformer 10 and supplies power to the exciter field winding 6 so that the output voltage of the AC generator 2 becomes a predetermined voltage. Control the amount. The AC generator 2 is started by supplying power from the initial drive power supply 18 to the exciter field winding 6 of the exciter 5 and using the separately excited excitation method. After the start-up, the initial drive power supply 18 is turned off. After that, the generator 2 is operated by the self-excitation method.

  The output of the AC generator 2 is supplied to the loads 121 and 122 of the private power generation facility via the feeder line 11. When the corresponding overcurrent relay 131 is activated due to the occurrence of a short circuit accident on the load 121 side, the corresponding load breaker 141 trips and the load 121 is disconnected from the AC generator 2. Similarly, when the corresponding overcurrent relay 132 is activated due to the occurrence of a short circuit accident on the load 122 side, the corresponding load breaker 142 trips and the load 122 is disconnected from the AC generator 2.

  The excitation current transformer 15 provided with a large number of taps is connected via a rectifier 16 between the exciter field winding 6 of the exciter 5 and the automatic voltage regulator 4 at a connection point 15ad. 15ad serves as an addition / subtraction means for adding the output of the exciting current transformer 15 and the output of the automatic voltage regulator 4. As a result of this addition, as will be described later, the excitation current of the exciter 5 due to a decrease in the output of the automatic voltage regulator 4 due to a short circuit accident caused by a short circuit accident caused by an overcurrent relay (protection relay) of the load fed from the generator 2 Compensating for the decrease, the output voltage of the generator is maintained at a predetermined value even in the event of a short-circuit accident to prevent malfunction of the protective relay when it is short-circuited. Maintained. The exciting current of the exciter 5 is detected by a shunt (divider) 17 and fed back to the automatic voltage regulator 4 from the input terminal 17in of the automatic voltage regulator 4 via the transmission line 171. The automatic voltage regulator 4 is excited. An output is output from the output terminal 4out so that the actual excitation current of the machine 5 becomes a predetermined value.

The loads 121 and 122 are supplied with power from the AC generator 2 through the power supply line 11. For example, when a short circuit accident occurs on the load 122 side, the load breaker 142 trips due to the operation of the overcurrent relay 132. This protects against short-circuit current.

  Next, the excitation control system of the excitation control device in FIG. 1 will be described with reference to FIG.

  In FIG. 2, in the automatic voltage regulator 4, the adding means 41 adds the output voltage of the generator 2 and the control target value input at the input terminal 101 in via the transmission line 101 including the instrument transformer 10, A signal indicating the difference between the output voltage of the generator 2 and the control target value is output from the adding means 41.

  The output of the adding means 41 is amplified by the amplifying unit A42 having a gain K1, and the output of the amplifying unit A42 is passed through the phase compensation unit 43 having a variable transfer function ((1 + Tlead · S) / (1 + Tlag · S)). Amplified by the amplification unit B44 of K2 and inputted to one input side of the first addition / subtraction means 45.

  On the other input side of the first addition / subtraction means 45, the actual excitation current of the exciter 5 having a fixed transfer function (KE / (1 + TE · S)) is automatically adjusted via the feedback signal path 171 including the shunt 17. Input from the input end 17e of the device 4.

  A signal of a difference between the input on one input side and the input on the other input side in the first addition / subtraction means 45 is output from the output terminal 4out of the automatic voltage regulator 4 as an output of the automatic voltage regulator 4; The signal is input to one input side of the second addition / subtraction means (the connection point) 15ad in the next stage.

  On the other input side of the second addition / subtraction means (the connection point) 15ad, the actual output current of the generator 2 detected by the exciting current transformer 15 having a variable transfer function (KEXCT / (1 + TEXCT · S)). Is input via the transmission line 161 including the current transformer 15 for excitation.

  The sum (current sum) obtained by adding the input on the other input side to the input on one input side in the second addition / subtraction means (the connection point) 15ad is the field winding 6 of the exciter 5. Flows as an excitation current.

  The output control of the generator 2 is performed by the output of the exciter 5 of the exciting current controlled by the control system described in the above paragraphs 0015 to 0020, and the functions and operations illustrated in FIG. 3 are performed.

  In FIG. 3, the generator 2 is controlled during the steady operation by the control by the transmission system described in the above paragraphs 0015 to 0020 based on the setting of each variable transfer function described above and the selection of the tap of the current transformer 15 for excitation. An operation with a predetermined voltage 2out and a predetermined output corresponding to the loads 121 and 122 is performed.

In the exemplary control apparatus illustrated in FIG. 8, in a steady operation state, for example, at time t1, the load 122
When a short circuit accident occurs on the side, the output voltage 2out of the generator 2 suddenly decreases as shown by the one-dotted line (28out (Fig. 8)) due to the occurrence of the short circuit current, and the automatic voltage regulator that cannot operate normally The output 4out of (AVR) 4 also decreases sharply as shown by the one-point difference line (158out (FIG. 8)), and the excitation current of the exciter field winding 6 also changes to the one-point difference line (6018 excitation current (FIG. 8)). As shown in the figure, the current suddenly decreases and the short-circuit current also decreases rapidly when there is no power supply other than the generator 2, so that the overcurrent relay 132 at the operation time T becomes inactive and the circuit breaker 142 may trip at time t2. In addition, the short circuit accident section on the load 122 side cannot be separated, and there is a possibility that the power supply from the generator 2 to the healthy load 121 will not be performed.

  On the other hand, according to the present embodiment illustrated in FIGS. 1 and 2, the above paragraphs 0015 to 0020 are based on the setting of each variable transfer function described above and the selection of the tap of the current transformer 15 for excitation. By the control by the described transmission system, for example, a short-circuit accident occurs at the load 122 side at the time t1 in a state where the steady operation of the predetermined voltage 2out and the predetermined output corresponding to the loads 121 and 122 is performed during the steady operation. In this case, the output voltage 2out of the generator 2 tries to suddenly decrease with the occurrence of the short circuit current, the output 4out of the automatic voltage regulator (AVR) 4 also tries to suddenly decrease, and the excitation current of the exciter field winding 6 also suddenly decreases. The output of the current transformer 15 for excitation increases due to a short-circuit current, and the increased output 15out is reduced by the second addition / subtraction means (connection point) 15ad by the automatic voltage regulator (AVR) 4 to be decreased. Decrease depending on the output of 4out If the total excitation current (4out + 15out) added at the time of short circuit is almost the same as the total excitation current (4out + 15out) during steady operation as shown by the thick solid line in FIG. In other words, if the above-described variable transfer functions are set so as to be substantially the same, and the tap of the excitation current transformer 15 is selected, the short-circuit current lasts for a predetermined period and the overcurrent relay 132 operates. At t2, the circuit breaker 142 trips and the short circuit accident section on the load 122 side is disconnected, and the output 4out of the automatic voltage regulator 4 does not drastically decrease as shown by the thick solid line in FIG. As shown by the thick solid line in FIG. 3, the output of the generator 2 is not drastically reduced, but power is supplied to the other healthy loads 121 continuously.

  Thus, based on the variable internal setting value in response to the output voltage of the generator 2 input from the output of the generator 2 through the excitation transformer 3 and input through the instrument transformer 10. The automatic voltage regulator 4 to be output, the feedback circuit 171 for feeding back the excitation current of the exciter 5 of the generator 2 to the output of the automatic voltage regulator 4, the excitation current and the automatic voltage fed back by the feedback circuit 171 A first addition / subtraction means 45 that outputs a difference from the output of the regulator 4, an excitation current transformer 15 that inputs the output current of the generator 2 and outputs it via the rectifier element 16, and the first addition / subtraction means The second adder / subtractor 15ad for adding the output of 45 and the output of the excitation current transformer 15 is provided, and a short-circuit accident occurred in the protection range by the protection relay 132 of the load 122 fed from the generator 2 Therefore, the decrease in the excitation current of the exciter 5 due to the decrease in the output of the automatic voltage regulator 4 is compensated by the output of the current transformer 15 for excitation, and the output voltage of the generator 2 is almost predetermined even at the time of the short circuit accident. By maintaining the value to prevent malfunction of the protective relay 132 during the short circuit, the trip of the load circuit breaker 142 is reliably performed when a short circuit accident occurs on the load 122 side during power feeding by the private power generation facility . In addition, power supply to other healthy loads 121 is continuously performed.

  Also, from a different point of view, the total excitation current (4out + 15out) added at the time of the short circuit is almost the same as the total excitation current (4out + 15out) during steady operation as shown by the thick solid line in FIG. As described above, according to conventional general wisdom, the above-described variable transfer function settings, tap selection of the excitation current transformer 15, etc., and adjustment work are adjustment test work at the time of on-site installation of power generation equipment. However, according to the present embodiment, setting at the design stage, selection of the tap of the current transformer 15 for excitation, and the like can be performed without performing the adjustment test work at the time of field installation. .

  For example, when selecting the tap of the current transformer 15 for excitation, if it is made too large to pass a continuous short-circuit current, a problem such as a large voltage fluctuation occurs when the load is interrupted. In the present embodiment, the tap of the exciting current transformer 15 is changed or the control constant of the automatic voltage regulator (AVR) 4 is readjusted in the adjustment test work at the time of installation of the power generation equipment. According to this, it is possible to appropriately select the tap of the excitation current transformer 15 and adjust the control constant of the automatic voltage regulator (AVR) 4 at the design stage, without performing the adjustment test work at the time of field installation. .

Hereinafter, examples of how to perform setting adjustment and selection of taps of the current transformer 15 for excitation in the design stage will be briefly described.
For the selection of the excitation current transformer tap, calculate the primary current, secondary current, and capacity of the current transformer for excitation separately from the rated current of the generator and the field current at the time of three-phase short circuit. Is selected.
The AVR control constants are automatically calculated by inputting the rating and constant data of the generator, exciter and current transformer for the exciter into the automatic calculation tool.

Embodiment 2. FIG.
The second embodiment is a case where a static exciter is used as the exciter 5 as illustrated in FIGS. 4 and 5. FIG. 4 is a connection diagram showing an example of the private power generation facility and its power supply system, and FIG. 5 is a block diagram illustrating the excitation control system of the excitation control device in FIG. 4 including the transfer functions of each part.
5 is different from FIG. 2 of the first embodiment described above in that the transfer function of the exciter 5 is (KE / (1 + TE · S) ³ ).

  The second embodiment also has the same functions and functions as those of the first embodiment.

Embodiment 3 FIG.
Hereinafter, the third embodiment will be described with reference to FIG. 6 which is a block diagram illustrating the excitation control system of the excitation control device including the transfer functions of each part.

  In the conventional self-excited AC generator excitation control device, when the overexcitation limiting function is provided, it is necessary to install an external device for reducing the field. In the third embodiment, the first embodiment described above is used. By adding an overexcitation limit block 46 to the transfer function block diagram of FIG. 2, field current control can be performed in consideration of the current from the current transformer 15 for excitation, so that an automatic voltage regulator (AVR) 4 can limit the overfield.

In the third embodiment, the overexcitation limiting block 46 is illustrated as having the transfer function (KF461), the transfer function (1 / (TF · S)), and the adding means 463.
In addition, the third embodiment also has the same function and the same effect as the first embodiment.

Embodiment 4 FIG.
Hereinafter, the fourth embodiment will be described with reference to FIG. 7, which is a block diagram illustrating the excitation control system of the excitation control device including the transfer functions of each part.

In the fourth embodiment, by adding an overexcitation limit block 46 to the transfer function block diagram in FIG. 5 of the above-described second embodiment, even when a static exciter is used as the exciter 5, excitation is performed. The field current can be controlled in consideration of the current from the current transformer 15, so that the overvoltage can be limited by the automatic voltage regulator (AVR) 4.
The fourth embodiment also has the same function and the same effect as the first embodiment.

  1 to 8, the same reference numerals indicate the same or corresponding parts.

It is a figure which shows Embodiment 1 of this invention, and is a connection diagram which shows an example of private power generation equipment and its electric power feeding system. FIG. 2 is a diagram illustrating the first embodiment of the present invention, and is a block diagram illustrating an excitation control system of the excitation control device in FIG. 1 including a transfer function of each part. It is a figure which shows Embodiment 1 of this invention, and is a figure explaining the function and operation | movement of FIG. It is a figure which shows Embodiment 2 of this invention, and is a connection diagram which shows an example of private power generation equipment and its electric power feeding system. FIG. 5 is a diagram illustrating a second embodiment of the present invention, and is a block diagram illustrating an excitation control system of the excitation control device in FIG. 4 including transfer functions of respective parts. It is a figure which shows Embodiment 3 of this invention, and is a block diagram which illustrates the excitation control system of an excitation control apparatus including the transfer function of each part. It is a figure which shows Embodiment 4 of this invention, and is a block diagram which illustrates the excitation control system of an excitation control apparatus including the transfer function of each part. It is a connection diagram which shows the example of the conventional private power generation equipment and its electric power feeding system.

Explanation of symbols

1 drive,
2 AC generator,
3 Excitation transformer,
4 Automatic voltage regulator (AVR),
401 transmission line,
4out output end,
45 First addition / subtraction means,
5 Exciter,
6 Exciter field winding,
7 Field breaker,
8 Rectifier,
9 Generator field winding,
10 Instrument transformer,
101 transmission line,
10in input end,
11 Feed line,
121, 122 load,
131,132 Overcurrent relay,
141, 142 load circuit breakers,
15 Current transformer for excitation,
151 transmission line,
15ad Second addition / subtraction means,
16 Rectifier,
17 shunt,
171 transmission line,
17in input end,
18 Initial drive power supply.

Claims (6)

  An automatic voltage regulator that outputs power based on a variable internal set value in response to an output voltage of the generator that takes power from an output of the generator via an excitation transformer and is input via an instrument transformer, A feedback circuit that feeds back the excitation current of the generator exciter to the output of the automatic voltage regulator, and a first addition / subtraction that outputs the difference between the excitation current fed back by the feedback circuit and the output of the automatic voltage regulator. Means, an excitation current transformer that inputs the output current of the generator and outputs it through a rectifying element, and a second addition / subtraction that adds the output of the first addition / subtraction means and the output of the excitation current transformer A reduction in the excitation current of the exciter due to a decrease in the output of the automatic voltage regulator due to a short circuit accident caused by a short circuit accident caused by a protection relay of a load fed from the generator. Compensating with the output of the current transformer for excitation, maintaining the output voltage of the generator at a substantially predetermined value even in the event of a short circuit accident, and preventing the malfunction of the protective relay at the time of the short circuit. Excitation control device for excitation AC generator.   2. The self-excited alternating current in the self-generated power facility according to claim 1, wherein the first adder / subtracter is built in the automatic voltage regulator. Generator excitation control device.   3. An excitation control device for a self-excited AC generator in a private power generation facility according to claim 2, wherein an overexcitation limiting function section is interposed between the first addition / subtraction means and the second addition / subtraction means. An excitation control device for a self-excited AC generator in a private power generation facility.   4. The self-excited alternating current generator for self-excited alternating current generator according to claim 3, wherein the overexcitation limiting function part is built in the automatic voltage regulator. Generator excitation control device.   5. The self-excitation control device for a self-excited AC generator in a private power generation facility according to any one of claims 1 to 4, wherein the exciter is a rotary exciter. AC generator excitation control device.   5. The self-excited AC generator excitation control apparatus for a self-generating apparatus according to claim 1, wherein the exciter is a static exciter. AC generator excitation control device.

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