JP6285167B2 - Thyristor type high voltage automatic voltage regulator - Google Patents

Description

  The present invention relates to a thyristor type high-voltage automatic voltage regulator attached to a distribution line, and relates to a technique that enables high-speed continuous tap switching while suppressing a temperature rise of a current limiting resistor.

  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 to be within the appropriate voltage range by a load-tap switching transformer or automatic voltage regulator, etc., but it is connected to renewable energy to the high-voltage distribution system, solar power generation for home use, etc. It is difficult to respond to sudden voltage fluctuations associated with the large-scale introduction of the system.

  Therefore, in recent years, a thyristor type high voltage 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 Non-Patent Document 1 below).

Aichi Electric Technical Report No.33, published on March 23, 2013, p. 7-12

  FIG. 2 shows the thyristor type high voltage automatic voltage regulator described in Non-Patent Document 1. In this automatic voltage regulator, the transformer connection is a V-star connection, and the low voltage circuit side of the voltage adjustment transformer ETr and the low voltage circuit side of the series transformer STr inserted in series with the line are thyristor type. As an indirect switching system coupled by a tap switch, a thyristor tap switch has a predetermined thyristor element turned on / off by a tap switch signal from a control device.

  The thyristor type tap changer includes tap switching thyristors Th1 to Th6 and current limiting fuses F1 and F2, a bridge thyristor Thb, and a current transformer CT mounted between the bridge thyristor Thb and the current limiting resistor R. The GU unit includes a snubber circuit, a surge absorber, and a gate driving 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 starting and stopping the automatic voltage regulator and during external / internal failure protection operation.

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

  Since the automatic voltage regulator shown in FIG. 2 employs a thyristor for the tap changer as described above, there is no limit on the number of tap changes. However, when the tap switching frequency is high, there is a problem that the current limiting resistor R excessively increases in temperature due to the circulating current at the tap switching.

  Therefore, in order to reduce the temperature rise of the current limiting resistor R even when the frequency of tap switching is high, the shortest tap switching interval (for example, 5 seconds) by the thyristor is set, and the temperature of the current limiting resistor R rises excessively. Is preventing.

  On the other hand, there is a problem that it becomes impossible to continuously perform tap switching with respect to a large voltage fluctuation. In order to solve this problem, an interlaced tap switching function is added to tap switching.

  However, since the shortest switching interval is set in the tap, a new problem that the voltage adjustment operation to the reference voltage is not performed when an instantaneous voltage drop occurs (see FIG. 3).

  FIG. 3 is a graph showing a result of voltage adjustment by a conventional thyristor type high voltage automatic voltage regulator. FIG. 3A shows the primary voltage of the automatic voltage regulator, and FIG. 3B shows the secondary voltage of the automatic voltage regulator.

  FIG. 3 (c) is an enlarged view when the secondary voltage shown in FIG. 3 (b) is instantaneously reduced (between broken lines), and FIG. 3 (d) shows how the tap changes when the secondary voltage is instantaneously reduced. ing. As shown in FIG. 3D, it can be seen that the tap switching by the thyristors Th1 to Th6 is not performed in the conventional automatic voltage regulator as shown in FIG. 3D in response to the occurrence of the instantaneous voltage drop shown in FIG.

  Therefore, in order to eliminate the above-described drawbacks, the present invention reliably suppresses the temperature rise of the current limiting resistor R even when the tap switching frequency is high, and reliably adjusts the voltage to the reference voltage even during an instantaneous power failure. The present invention provides a thyristor type high voltage automatic voltage regulator that can be used.

  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 high voltage 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 to switch the tap of the voltage adjustment transformer. The control device is configured to stop the tap switching by the thyristor when the temperature rise value of the current limiting resistor for suppressing the circulating current at the time of the tap switching becomes higher than a specified value.

  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. In the thyristor type high voltage 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 to switch the tap of the voltage adjustment transformer. The controller calculates a temperature rise value of the current limiting resistor that suppresses the circulating current at the time of tap switching from the current value flowing through the current limiting resistor, and when the value becomes higher than a specified value, the thyristor It is characterized in that it is configured to stop the tap switching by.

  The invention described in claim 3 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 high voltage 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 to switch the tap of the voltage adjustment transformer. The control device is configured to stop when the number of tap switching by the thyristor exceeds a specified number within the latest fixed time.

  According to a fourth aspect of the present invention, in the thyristor type high voltage automatic voltage regulator according to any one of the first to third aspects of the present invention, when the control device performs through control, tap switching by the thyristor is not stopped. Features.

  According to the first aspect of the present invention, when the temperature rise value of the current limiting resistor exceeds the specified value, the control device stops the tap switching by the thyristor. It can be reliably prevented from rising.

  According to the second aspect of the present invention, the temperature rise value of the current limiting resistor is calculated from the current value flowing through the current limiting resistor, and when the value becomes higher than the specified value, tap switching by the thyristor is performed. Therefore, it is not necessary to prepare a separate device for detecting the temperature of the current limiting resistor.

  According to the third aspect of the present invention, the controller is configured to stop when the number of tap switching by the thyristor exceeds the specified number within the most recent fixed time. The functional configuration of the apparatus can be simplified.

  According to the fourth aspect of the present invention, even when the temperature rise value of the current limiting resistor exceeds the specified value, the control device is configured not to stop the tap switching by the thyristor when the control device performs control. The protection function can be prevented from being hindered by the tap switching stop due to the temperature rise of the current limiting resistor.

It is a graph which shows the voltage adjustment result by the thyristor type high voltage automatic voltage regulator of this invention. It is a circuit diagram which shows a thyristor type high voltage | pressure automatic voltage regulator. It is a graph which shows the voltage adjustment result by the conventional thyristor type high voltage automatic voltage regulator.

  Embodiments of the present invention will be described below. Since the circuit configuration of the thyristor type high voltage automatic voltage regulator according to the present invention is the same as the circuit configuration of the conventional thyristor type high voltage automatic voltage regulator described above, the embodiment of the present invention is also shown in FIG. This will be described with reference to a circuit diagram.

  A feature of the thyristor type high voltage automatic voltage regulator of the present invention is that the control device shown in FIG. 2 is configured to have a function of preventing the current limiting resistor R from rising in temperature. As a first embodiment, when the current value flowing through the current limiting resistor R is detected by the control device, the temperature rise value of the current limiting resistor R is calculated from the current value, and the value exceeds the specified value Has a method of stopping tap switching by the thyristors Th1 to Th6.

  As a result, the problem that the current limiting resistor R is excessively heated can be surely solved, and unlike the conventional thyristor type high voltage automatic voltage regulator, the shortest tap switching interval is not set in the thyristors Th1 to Th6. Even when the instantaneous voltage drop of the high-voltage distribution line decreases, the voltage adjustment to the reference voltage can be reliably executed. Further, since the temperature rise of the current limiting resistor R can be detected by the calculation function of the control device, it is not necessary to prepare a separate device for detecting the temperature rise of the current limiting resistor R.

  As a second embodiment of the function of preventing the temperature rise of the current limiting resistor R, when the number of tap switching in the latest fixed time (for example, 60 seconds) exceeds a specified number (for example, 12), the thyristors Th1 to Th1. There is a method of stopping the tap switching by Th6.

  Also in this case, as in the first embodiment, the temperature rise of the current limiting resistor R can be reliably prevented, and the voltage adjustment to the reference voltage can be reliably executed even when the instantaneous voltage drops. Further, since the temperature increase of the current limiting resistor R may be performed by using the counting function of the control device, no special change is required in the configuration of the voltage regulator as in the first embodiment.

  Further, the thyristor type high voltage automatic voltage regulator of the present invention is capable of tap switching by the thyristors Th1 to Th6 even if the temperature rise value of the current limiting resistor R exceeds a specified value when the control device performs the control. Control not to stop.

  The through control of the control device is a function of protecting the device itself in the event of a distribution line accident or internal failure of the device, and protecting the distribution line from being affected. Specifically, when overcurrent due to distribution line short-circuit is detected by the control unit, when overload current is detected by the control unit, or when distribution line voltage is monitored and overvoltage or undervoltage is detected by the control unit Or, when a series transformer's low voltage circuit side open accident or a voltage regulation transformer's low voltage circuit side short circuit accident that occurs when the thyristor is misfired, or the result of individual monitoring of each unit A case where abnormality is detected can be exemplified.

  In other words, even when the temperature of the current limiting resistor R rises excessively, by performing control so as not to stop the tap switching, it is possible to reliably execute the above-described protection function without hindering the through control of the control device. It can be secured.

  FIG. 1 is a graph showing a voltage adjustment result by the thyristor type high voltage automatic voltage regulator of the present invention. FIG. 1 (a) shows the primary voltage of the automatic voltage regulator, and FIG. 1 (b) shows the secondary voltage of the automatic voltage regulator.

  FIG. 1C is an enlarged view when the secondary voltage shown in FIG. 1B is instantaneously decreased (between broken lines), and FIG. 1D shows the state of tap changes when the secondary voltage is instantaneously reduced. ing. When the instantaneous voltage drop shown in FIG. 1B occurs, the automatic voltage regulator of the present invention reliably performs the tap switching by the thyristors Th1 to Th6 and suppresses the instantaneous voltage drop as shown in FIG. 1D. It can be confirmed that it is made.

  As described above, according to the thyristor type high-voltage automatic voltage regulator of the present invention, the tap switching is realized by the thyristor, thereby eliminating the limit of the number of tap switching and the current limiting resistor R, unlike the mechanical tap switching. By eliminating the shortest tap switching interval employed for the purpose of suppressing excessive temperature rise, voltage adjustment to the reference voltage can be reliably performed even when instantaneous voltage fluctuation occurs.

  Furthermore, when the temperature of the current limiting resistor R rises excessively, the tap switching is stopped by the control device, so that the current limiting resistor R can be protected and the temperature rising of the current limiting resistor R is excessive. Even if this occurs, it is extremely advantageous that consideration is given so that the through control of the control device for the purpose of protection operation and the like is not hindered.

  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-Th6 Thyristor for tap switching Thb Thyristor for bridge F1, F2 Current limiting fuse R Current limiting resistor MC1, MC2 Electromagnetic contactor

Claims (4)

  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 high voltage automatic voltage regulator that switches and switches the tap of the voltage regulating transformer by switching the thyristor so as to adjust the voltage of the distribution line to a preset reference voltage, the control device is configured to switch the tap at the time of tap switching. A thyristor type high voltage automatic voltage regulator configured to stop tap switching by a thyristor when a temperature rise value of a current limiting resistor for suppressing circulating current becomes higher than a specified value. 2. The thyristor type high voltage automatic voltage regulator according to claim 1, wherein the control device calculates a temperature rise value of the current limiting resistor from a value of a current flowing through the current limiting resistor.   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 high voltage automatic voltage regulator, which switches the tap of the voltage regulating transformer by switching the thyristor so that the voltage of the distribution line is adjusted to a preset reference voltage, the control device performs tap switching by the thyristor. A thyristor-type high-voltage automatic voltage regulator, characterized in that the thyristor type high-voltage automatic voltage regulator is configured to stop when the number of times exceeds a specified number within the latest fixed time.   The thyristor type high-voltage automatic voltage regulator according to any one of claims 1 to 3, wherein the control device is configured not to stop tap switching by the thyristor when performing through control.

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