JP6077247B2 - Static high voltage automatic voltage regulator - Google Patents

Description

  The present invention relates to an automatic voltage regulator attached to a distribution line, and relates to a technique for suppressing an excitation inrush current generated at tap switching.

  In recent years, a large amount of renewable energy has been introduced to realize a low-carbon society. In addition, due to power supply instability due to the 2011 off the Pacific coast of Tohoku Earthquake that occurred in March 2011, the momentum for switching to domestic renewable energy has further increased.

  On the other hand, when a large amount of renewable energy is connected to the power distribution system, there is a risk of sudden voltage fluctuations. The high-voltage distribution system is controlled so as to be within the appropriate voltage range by a load-changing tap changer or automatic voltage regulator, but it is connected to renewable energy to the high-voltage distribution system and household solar power generation. It is difficult to respond to sudden voltage fluctuations due to large-scale introduction of

  Therefore, in recent years, a thyristor type automatic voltage regulator that can cope with a rapid voltage fluctuation and can perform voltage adjustment at high speed and frequently has been attracting attention (see Patent Document 1 below).

Japanese Patent No. 3506808

  FIG. 2 shows an example of the automatic voltage regulator described in Patent Document 1, in which a transformer is configured by VV connection. Specifically, one end of the secondary windings 2su and 2sw of the two series transformers 2u and 2w inserted in series with the line is connected to the U-phase and W-phase power supply side main circuit terminals TU and TW, and the secondary The other ends of the windings 2su and 2sw are connected to main circuit relay terminals TU ′ and TW ′.

  The primary windings 2pu and 2pw of the series transformers 2u and 2w are V-connected, and each is connected to the adjustment voltage input terminals tu to tw via the current limiting reactors 6u to 6w. Further, the primary windings 3pu and 3pw of the two voltage adjusting transformers 3u and 3w inserted between the lines are V-connected, and the three-phase terminals are connected to the second load side main circuit terminals Tu to Tw. Yes.

  The secondary windings 3su and 3sw of the voltage adjustment transformers 3u and 3w have taps t1 to tn, respectively, and are connected to the three-phase adjustment voltage output terminals tu ′ to tw ′ via the thyristor tap switch 4. ing. The thyristor tap changer 4 is controlled by a control device 5.

  Here, when the taps t1 to tn are switched by the thyristor tap switch 4, the tap voltages of the voltage adjusting transformers 3su and 3sw are applied to the primary windings 2pu and 2pw of the series transformers 2u and 2w.

  At this time, the core voltage of the series transformers 2u, 2w is saturated by the applied tap voltage value, the applied phase, and the residual magnetic flux at the time of application, and the primary windings 2pu, 2pw become the same state as the air-core reactor, and the series transformer 2pu , 2pw exciting inductance is drastically reduced and a large inrush current flows, but this current is reliably suppressed by the current limiting reactors 6u to 6w.

  However, the current-limiting reactors 6u to 6w are normally air-core in order to suppress the overcurrent due to the short-circuit accident of the high-voltage distribution line to the low-voltage side due to the iron core saturation of the series transformer. Therefore, there are disadvantages that the outer shape and loss of the current limiting reactor increase and the outer shape and mass of the entire device increase.

  The present invention proposes a static high voltage automatic voltage regulator having a configuration capable of effectively suppressing the magnetizing inrush current while eliminating the above-mentioned drawbacks.

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. , coupled with said thyristor type tap changers, the static pressure automatic voltage regulator by switching the thyristor to adjust the reference voltage is set to voltage distribution lines previously switching the taps of the voltage regulator transformer, the By winding the high-voltage winding of the series transformer inside and winding the low-voltage winding outside, compared to the normal winding structure with the low-voltage winding inside and the high-voltage winding outside, the series transformer The air core inductance of the low voltage winding is set large.

The invention described in claim 2 is composed of a transformer, a thyristor tap changer, and a controller, 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. , coupled with said thyristor type tap changers, the static pressure automatic voltage regulator by switching the thyristor to adjust the reference voltage is set to voltage distribution lines previously switching the taps of the voltage regulator transformer, the By winding the high-voltage winding of the series transformer inside and winding the low-voltage winding outside, compared to the normal winding structure with the low-voltage winding inside and the high-voltage winding outside, the series transformer The air core inductance of the low-voltage winding is set to be large, and the thyristor is configured to be controlled by the control device so that the thyristor is always turned on at the peak of the excitation voltage of the voltage adjusting transformer. And butterflies.

  According to the first aspect of the present invention, it is possible to effectively suppress the magnetizing inrush current by omitting the current limiting reactor by setting the air-core inductance of the low-voltage winding of the series transformer to be large.

According to the invention of claim 2 , the current limiting reactor is omitted by setting the air core inductance of the low-voltage winding of the series transformer large and always turning on the thyristor at the peak of the excitation voltage of the voltage regulating transformer. However, it is possible to effectively suppress the magnetizing inrush current.

It is a circuit diagram which shows the static high voltage automatic voltage regulator of this invention. It is a circuit diagram which shows the conventional static type high voltage automatic voltage regulator.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a circuit diagram showing a static high voltage automatic voltage regulator A of the present invention. In the automatic voltage regulator A shown in FIG. 1, the connection of the transformer is a V-star connection.

  Specifically, this is an indirect switching system in which the low voltage circuit side of the voltage regulating transformer ETr and the low voltage circuit side of the series transformer STr inserted in series in the line are coupled by a thyristor type tap switch, and the thyristor type tap switch The predetermined thyristor element is turned on / off by a tap switching signal from the control device.

  The thyristor type tap changer is constituted by a GU unit including a tap change thyristor Th1 to Th6 and a current limiting fuse, a bridge thyristor Thb and a transformer CT, a snubber circuit, a surge absorber, and a gate drive device. The control device includes a control unit that performs voltage adjustment control and protection control against external / internal failures of the device, a control unit that includes a GA unit that selects a combination of thyristors from a tap switching command signal from the control unit, and a power source unit. The unit includes an MC unit that opens and closes the magnetic contactors MC1 and MC2 in response to a command from the control unit when the automatic voltage regulator A starts and stops operation and when an external / internal failure protection operation is performed.

  The thyristor tap changer and the control device are housed in a control box, and the automatic voltage regulator A of the present invention is configured.

  The automatic voltage regulator A configured as described above performs analog processing on the voltage and current elements captured by the control unit of the control device, performs A / D conversion, and performs digital arithmetic processing by the CPU, thereby A combination of thyristors to be turned on / off is selected so that the voltage is adjusted to a preset reference voltage.

  Here, when the thyristor is turned on, a large magnetizing inrush current flows as described above. The automatic voltage regulator A of the present invention omits the current-limiting reactor that suppresses this, but effectively suppresses the magnetizing inrush current by setting the air-core inductance of the low-voltage winding of the series transformer STr large. Yes.

  Specifically, by winding the high-voltage winding of the series transformer STr on the inside and winding the low-voltage winding on the outside, compared to a normal winding structure (low-voltage winding is inside and high-voltage winding is outside), Air core inductance is set large. This is nothing but the series winding STr of the automatic voltage regulator A is excited from the low voltage winding.

  In addition, by using synchronous control that always turns on the thyristor at the peak of the excitation voltage of the voltage adjustment transformer, even if the current limiting reactor is omitted, the excitation inrush current is effectively suppressed, and the device A is small and lightweight. Could be realized.

  The voltage regulator A is installed at 5 [km] or more from the substation, thereby limiting the overcurrent due to the short circuit accident of the high voltage distribution line to 2 [kA] or less, and the current flowing through the thyristor By setting the allowable overload capacity or less, the current limiting reactor can be omitted.

  As described above, the static high-voltage automatic voltage regulator of the present invention increases the air-core inductance of the low-voltage winding of the series transformer, so that even if the current-limiting reactor is omitted, the magnetizing inrush generated at the tap switching The current can be reliably suppressed.

  In addition, by using synchronous control that always turns on the thyristor at the peak of the excitation voltage of the voltage adjustment transformer, even if the current limiting reactor is omitted, it is possible to reliably suppress the excitation inrush current that occurs when the tap is switched. It becomes possible.

  Furthermore, the static high voltage automatic voltage regulator of the present invention is used in combination with the synchronous control in which the air core inductance of the low voltage winding of the series transformer is increased and the thyristor is always turned on at the peak of the excitation voltage of the voltage regulating transformer. As a result, even if the current limiting reactor is omitted, it is possible to reliably suppress the magnetizing inrush current that is generated at the time of tap switching, and to realize a reduction in size and weight of the device A.

  The present invention is highly likely to be used in equipment that can handle voltage fluctuations in the distribution system.

STr Series transformer ETr Voltage regulation transformer VT, CT Transformer Th1 to Th6 Tap switching thyristor Thb Bridge thyristor F1, F2 Current limiting fuse R Current limiting resistance MC1, MC2 Electromagnetic contactor A Static high voltage automatic voltage regulator

Claims (2)

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 a static high voltage automatic voltage regulator that switches the thyristor to switch the tap of the voltage regulating transformer to adjust the voltage of the distribution line to a preset reference voltage, the high voltage winding of the series transformer is connected By winding inside and winding the low- voltage winding outside, the air-core inductance of the low-voltage winding of the series transformer is increased compared to the normal winding structure with the low-voltage winding inside and the high- voltage winding outside. Static high voltage automatic voltage regulator characterized by setting. 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 a static high voltage automatic voltage regulator that switches the thyristor to switch the tap of the voltage regulating transformer to adjust the voltage of the distribution line to a preset reference voltage, the high voltage winding of the series transformer is connected By winding inside and winding the low- voltage winding outside, the air-core inductance of the low-voltage winding of the series transformer is increased compared to the normal winding structure with the low-voltage winding inside and the high- voltage winding outside. And the thyristor is controlled by the controller so that the thyristor is always turned on at the peak of the excitation voltage of the voltage regulating transformer. Voltage regulator.

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