JP2018174600A - Thyristor type automatic voltage regulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of taps of a low voltage circuit side winding of a voltage adjusting transformer as much as possible, and to increase the number of tap voltages for voltage adjustment as much as possible by combination thereof, and to make the voltage between taps for voltage adjustment equal. A thyristor-type automatic voltage regulator that achieves quasi-linear control is provided. SOLUTION: A tap voltage ratio of a low-voltage circuit side winding of a voltage adjusting transformer is set to a ratio of different voltages of 1: 3: 2, and a tap voltage for voltage adjustment is configured by a combination thereof. [Selection diagram] Fig. 2

Description

  The present invention relates to a thyristor type automatic voltage regulator attached to a distribution line, and enables feedback control of the distribution line voltage by greatly increasing the number of taps and equalizing the voltage between taps. The present invention relates to a technique for adjusting a distribution line voltage without using a fixed-time type or integral type voltage regulator relay.

  In recent years, a large amount of renewable energy has been introduced to realize a low-carbon society. When a large amount of renewable energy is connected to the power distribution system, there is a risk of sudden voltage fluctuations.

As a device that can cope with such a rapid voltage fluctuation, a thyristor type automatic voltage regulator exemplified in the following Non-Patent Document 1 has attracted attention.

"Thyristor type automatic voltage regulator catalog", Aichi Electric Co., Ltd., created in November 2016, [Search on February 23, 2017], Internet <http://www.aichidenki.jp/products/catalog_pdf/tvr. pdf>

  The thyristor type automatic voltage regulator is composed of a series transformer inserted in series in the distribution line, a voltage adjustment transformer inserted between the lines of the distribution line, tap switching thyristors Th1 to Th6, and a bridge thyristor Thb. Consists of a thyristor-type tap changer, a current limiting resistor R connected to the bridge thyristor Thb, etc., and by switching the tap thyristor at high speed and frequently in response to sudden voltage fluctuations, power distribution It is possible to control the system voltage to be within an appropriate range.

  The above configuration is a configuration between one line. The voltage regulation transformer and the series transformer are connected by the V-star system, but there are other methods such as the V-V system and the star-star system. However, the present invention is a technique that can be applied regardless of the function of the thyristor type automatic voltage regulator such as the connection system or the three-phase unbalance suppression function.

  The thyristor type automatic voltage regulator having the above-described configuration includes a total of seven tap thyristors Th1 to Th6 constituting a thyristor tap changer and one bridge thyristor Thb. In this case, as shown in FIGS. 3A and 3B, the maximum number of taps for voltage adjustment was only 7.

  For this reason, when the voltage adjustment range is ± 300 V, the voltage between taps of the voltage adjustment is 100 V, and the step voltage is coarse with respect to the voltage adjustment range, and fine voltage adjustment cannot be performed.

  Accordingly, the present invention provides a thyristor type automatic voltage regulator by greatly increasing the number of tap points and reducing the step voltage with respect to the voltage adjustment range and switching the thyristor so that the adjustment voltage is finely and linearly increased or decreased. It is intended to provide an automatic voltage regulator capable of realizing quasi-linear voltage control that feedback-controls the distribution line voltage, assuming that is a substantially linear voltage amplifier.

  The invention according to claim 1 is composed of a transformer, a thyristor tap changer, and a control device, and includes a low voltage circuit side of the voltage regulating transformer and a low voltage circuit side of the series transformer inserted in series with the line. In the thyristor type automatic voltage regulator, which is coupled by the thyristor type tap changer, and switches the thyristor so as to adjust the voltage of the distribution line to a preset reference voltage, the tap of the voltage adjustment transformer is changed. It is characterized in that a tap voltage for voltage adjustment is configured by combining the tap turns ratio of the low-voltage circuit side winding of the adjustment transformer as a ratio of different voltages.

  The invention described in claim 2 is characterized in that, in the invention described in claim 1, the turn ratio is a different voltage ratio of 1: 3: 2.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the linear control for switching and controlling the thyristor so that the voltage between the taps for voltage adjustment becomes equal and the adjustment voltage linearly increases or decreases. The voltage control is performed by using the voltage regulating relay.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the control device feedback-controls the time average value of the detected distribution line voltage to appropriately adjust the distribution line voltage. It has a special feature.

  The invention according to claim 5 is characterized in that, in the invention according to claim 3 or 4, the control device performs a voltage control by providing a dead band in the voltage adjustment relay of the quasi-linear control.

  The invention according to claim 6 is characterized in that, in the invention according to any one of claims 1 to 5, the series transformer is any one of V connection, Δ connection, and star connection.

  According to the first aspect of the present invention, the voltage adjustment tap voltage is configured by combining the ratio of the turns between the taps of the low-voltage circuit side winding of the voltage adjustment transformer with the ratio of the different voltages, thereby reducing the number of thyristors. It is possible to extract the number of taps.

  According to the second aspect of the invention, the quasi-two rear control with the same voltage between taps is made possible by setting the turns ratio to a different voltage ratio of 1: 3: 2.

  According to the third aspect of the present invention, in the control device, the quasi-linear control voltage adjustment relay for switching and controlling the thyristor so that the voltage between the taps for voltage adjustment becomes equal and the adjustment voltage is finely and linearly increased and decreased. By using it, the thyristor type automatic voltage regulator can be regarded as a substantially linear voltage amplifier.

  According to the invention described in claim 4, the voltage of the distribution line is controlled by feedback-controlling the time average value of the distribution line voltage detected by the control device without using the conventional time limit type or integral type voltage regulating relay. Can be adjusted appropriately in the shortest time.

  According to the fifth aspect of the present invention, it is possible to appropriately control the switching frequency of the thyristor by providing the dead zone in the quasi-linear control voltage adjustment relay.

  According to invention of Claim 6, it becomes applicable irrespective of the connection system of an automatic voltage regulator.

FIG. 3 is a circuit diagram of one thyristor type automatic voltage regulator of the present invention per line. (A) is a circuit diagram which shows the connection state of the thyristor and voltage adjustment transformer which comprise the thyristor type automatic voltage regulator of this invention, (b) is the ON state of the said thyristor, and adjustment voltage (tap of voltage adjustment) It is a table | surface which shows the relationship of a voltage. (A) is a circuit diagram which shows the connection state of the thyristor and voltage adjustment transformer which comprise the conventional thyristor type automatic voltage regulator, (b) is the ON state of said thyristor, and adjustment voltage (tap voltage of voltage adjustment) ).

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a circuit diagram showing a configuration of a thyristor type automatic voltage regulator A according to the present invention installed between distribution lines (per one) of a distribution system. The automatic voltage regulator A shown in FIG. 1 includes a series transformer 2 (high voltage circuit side winding 2a and low voltage circuit side winding 2b) connected in series to the distribution line 1, and a low voltage circuit side winding of the series transformer 2. The voltage adjustment transformer 3 (high voltage circuit side winding 3a and low voltage circuit side winding 3b) connected in series to 2b, the low voltage circuit side winding 2b of the series transformer 2, and the low voltage circuit side winding of the voltage adjustment transformer 3 A thyristor tap changer 4 connected between the lines 3b and a short-circuit prevention circuit 5 connected in parallel to the voltage adjustment transformer 3 are schematically configured.

  The thyristor tap changer 4 is configured by bridge-connecting eight thyristors Th1 to Th8, and the short-circuit prevention circuit 5 is configured by connecting a thyristor Thb for bridge and a current limiting resistor R in series.

  Between the thyristor tap changer 4 and the voltage adjustment transformer 3, protective fuses F1 to F3 for protecting the thyristors Th1 to Th8 from overcurrent are connected. In parallel with the short-circuit prevention circuit 5, a switch (a switch having a large current capacity such as an electromagnetic contactor) 6 that is turned on when the apparatus is abnormal is connected.

  When the voltage of the distribution line changes due to a load change or the like, the automatic voltage regulator A configured as described above has a voltage between the distribution line 1 and a reference voltage set in advance by a command signal output from a control device (not shown). Tap selection of the thyristor tap changer 4 is performed so as to reduce the difference. In response to this, tap switching is performed by the thyristors Th1 to Th8, and the voltage range of the distribution system is controlled to be within the appropriate voltage range.

  When switching the thyristors Th1 to Th8, the bridge thyristor Thb is turned on and the thyristors Th1 to Th8 are turned off. Then, the current flowing in any of the thyristors Th1 to Th8 is commutated to the current limiting resistor R, and the thyristors Th1 to Th8 are turned off. Thereafter, the thyristor to be switched is turned on, and the bridge thyristor Thb is turned off. As described above, since current flows through the current limiting resistor R every time the tap is switched, heat is generated in the current limiting resistor R and the temperature rises.

  FIG. 2A shows a connection state between the thyristors Th1 to Th8 and the voltage adjustment transformer 3. FIG. The case where the voltage adjustment range is set to ± 300 [V] is illustrated, and the voltage composition ratio of different voltages such as 50 [V], 150 [V] and 100 [V] is adopted as the tap voltage.

  FIG. 2B shows the relationship between the ON state of the eight thyristors Th1 to Th8 shown in FIG. As shown in FIG. 2 (b), the automatic voltage regulator A of the present invention comprises a thyristor tap switch 4 composed of eight thyristors Th1 to Th8, and the voltage between the tap windings of the voltage regulating transformer 3 is determined. By setting the voltage to 50 [V], 150 [V], and 100 [V], 13 taps can be drawn with a step voltage equal to 50 [V].

  That is, in the conventional automatic voltage regulator shown in FIG. 3, the tap extraction of 7 points using 6 thyristors is realized, but the 13 points of tap extraction are realized by 8 thyristors.

  As a result, the voltage between taps of the voltage adjustment of the automatic voltage regulator A is ½ of that of the conventional automatic voltage regulator, so that finer voltage adjustment is possible and so-called quasi-linear control closer to linear control is performed. Can be realized.

  Further, when the voltage between taps of the voltage adjustment of the automatic voltage regulator A of the present invention is set to 100 [V] as in the conventional automatic voltage regulator, the conventional voltage adjustment range of 2 can be obtained only by increasing two thyristors. A voltage adjustment of ± 600 [V] that is doubled becomes possible.

  The control device (not shown) constituting the automatic voltage regulator A of the present invention includes a voltage regulator relay incorporating a compensator (compensator having no integrator such as a proportional regulator) for feedback control of the distribution line voltage. used. By using this voltage adjustment relay, the voltage can be directly adjusted up to the upper and lower limits of the voltage adjustment range, and fine voltage adjustment is possible, so that voltage control in the shortest time is possible.

  Moreover, the said control apparatus can control the voltage value nearer to the voltage management reference | standard of a distribution line by carrying out the time average of the detected voltage of the distribution line 1 in time. In addition, since the detection voltage is smoothed, tap switching is not performed with a slight voltage fluctuation, and the number of tap switching is suppressed. As a result, tap switching is performed for slight voltage fluctuations, and current flows through the current limiting resistor R each time switching is performed, so that the current limiting resistor R excessively rises in temperature and cannot be switched. Can be reliably prevented.

  Further, the control device achieves the same effect as described above by suppressing the switching frequency of the thyristor by providing a dead band in the voltage adjustment relay for quasi-linear control.

  1 illustrates the case where the series transformer 2 is star-connected as the automatic voltage regulator A according to the present invention, but the automatic voltage regulator A of the present invention is not limited to this configuration. Of course, the series transformer 2 may be connected by V connection or Δ connection.

As described above, according to the automatic voltage regulator A of the present invention, compared to the conventional case,
Quasi-linear control is made possible by greatly increasing the number of tap points and making the voltage between taps equal.

  Further, as can be seen from the above description, the present invention is a technique that can be applied regardless of functions such as a connection method of an automatic voltage regulator and a three-phase unbalance suppression function.

  The present invention is used for a device corresponding to a voltage fluctuation of a distribution system.

DESCRIPTION OF SYMBOLS 1 Distribution line 2 Series transformer 2a High voltage circuit side winding of a series transformer 2b Low voltage circuit side winding of a series transformer 3 Voltage adjustment transformer 3a High voltage circuit side winding of a voltage adjustment transformer 3b Low voltage of a voltage adjustment transformer Circuit side winding 4 Thyristor type tap changer Th1 to Th8 Thyristor 5 Short circuit prevention circuit Thb Bridge thyristor R Current limiting resistor 6 Switch A Thyristor type automatic voltage regulator

Claims (6)

  It consists of transformer, thyristor tap changer, and control device, and the low voltage circuit side of the voltage regulation transformer and the low voltage circuit side of the series transformer inserted in series with the line are the thyristor tap changer. In the thyristor type automatic voltage regulator, which switches the thyristor to switch the tap of the voltage regulating transformer so as to adjust the voltage of the distribution line to a preset reference voltage, the low voltage circuit side winding of the voltage regulating transformer A thyristor type automatic voltage regulator characterized in that a tap voltage for voltage regulation is configured by combining the tap turns ratio of a wire with a ratio of different voltages.   2. The thyristor type automatic voltage regulator according to claim 1, wherein the turn ratio is a different voltage ratio of 1: 3: 2.   The control device performs voltage control using a linear control voltage adjustment relay that switches and controls a thyristor so that the voltage between taps for voltage adjustment becomes equal and the adjustment voltage linearly increases and decreases. The thyristor type automatic voltage regulator according to any one of claims 1 and 2.   The thyristor type automatic voltage according to any one of claims 1 to 3, wherein the control device feedback-controls a time average value of the detected distribution line voltage to appropriately adjust the distribution line voltage. Adjuster.   The thyristor type automatic voltage regulator according to any one of claims 3 and 4, wherein the control device performs voltage control by providing a dead zone in a quasi-linear control voltage regulation relay.   The thyristor type automatic voltage regulator according to any one of claims 1 to 5, wherein the series transformer is any one of a V connection, a Δ connection, and a star connection.

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