JPH0256013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a static automatic voltage regulator that adjusts line voltage by switching taps using a thyristor switch.

The static automatic voltage regulator uses a thyristor switch instead of the conventional mechanical tap changer, making it contactless.
There is no limit to the number of times the taps can be switched, and the operating time can be shortened. In order to avoid adverse effects on the load in the event of a failure of the voltage regulator, the applicant has previously installed a sheath disconnector and a switch on the power supply side and the load side of the voltage regulator, and immediately shuts off the voltage regulator in the event of a failure. We proposed a static automatic voltage regulator that disconnects from the line and simultaneously closes the switch that bypasses the voltage regulator to prevent load power outages. In this voltage regulator, when a voltage regulator malfunctions, the circuit breaker installed on the power supply side is first activated, then the switch installed on the load side is opened, and the voltage is adjusted after confirming these opening operations. A control circuit using an auxiliary relay etc. is used to close the switch that bypasses the device. However, in order to carry out such a control operation, the control circuit becomes extremely complicated, and the use of an auxiliary relay has the disadvantage of causing a time delay in the control operation. In particular, due to the delay in closing of the switch that bypasses the voltage regulator, there is a time when the line on the power supply side and the line on the load side are cut off, which has the disadvantage that the power to the load is cut off for a short time. Ta.

An object of the present invention is to provide a static automatic voltage regulator that can simplify the configuration of a control circuit and eliminate load power outages.

The present invention provides a shield circuit breaker and a switch on the power supply side and load side of a voltage regulator, respectively, and connects the circuit breaker to the voltage regulator side between the power supply side terminal of the circuit breaker and the load side terminal of the switch. It is an automatic voltage regulator equipped with a switch for the side road, and as a switch for the side road, when both the disconnector and the switch installed on the power supply side and the load side of the voltage regulator open, It is characterized by using a self-conducting semiconductor switch.

The automatic voltage regulator of the present invention will be described in detail below with reference to the drawings.

FIG. 1 schematically shows the overall configuration of the present invention. In the same figure, reference numeral 1 indicates, for example, a thyristor as a tap selection switch at each tap of regulating transformers T and T, as shown in FIG. Switch S ₁ , S ₂ ,
... is connected to a direct switching voltage regulator, 2 is a power supply, and 3 is a load. A disconnector 5 is inserted on the power side of the voltage regulator 1 to open and close between the voltage regulator and the power line 4, and a disconnector 5 is inserted on the load side of the voltage regulator 1 to connect the voltage regulator and the load. A switch 7 that opens and closes between the side track 6 and the side track 6 is inserted. A control power transformer 8 is connected to the power supply side of the shield breaker 5 , and the output of the control power transformer 8 is supplied to a control circuit 9 . In addition to conducting the thyristor switch of a predetermined tap of the voltage regulator to select the tap so as to maintain the line voltage at a predetermined value, the control circuit 9 also operates a current transformer 1 that detects the current flowing through the voltage regulator.
A short circuit or an open tap state in the voltage regulator is detected by the output such as 0, and a control operation is performed to control the shield breaker 5 and the switch 7. For example, when a short circuit current is detected, the circuit breaker 5 is immediately opened,
Subsequently, the switch 7 is opened to disconnect the voltage regulator from the line, thereby preventing any influence on the load.

In order to bypass the voltage regulator and prevent a power outage to the load in the event of a failure of the voltage regulator, a self-conducting function is provided across the power supply side terminal of the shield breaker 5 and the load side terminal of the switch 7. A semiconductor switch 11 having a semiconductor switch 11 is connected thereto. . _This semiconductor switch 11, for _example , as shown in _{FIG .} The circuit and surge absorption varistor D ₀ are connected in parallel, and the capacitor C ₀ , resistor R ₀ and surge absorption varistor
D ₀ constitutes a snubber circuit. A diode is connected between the cathode and gate of thyristor Th ₁ .
A series circuit of D ₁ , D ₂ and a Zener diode DZ ₁ is connected, and a series circuit of diodes D ₃ , ₄ and a Zener diode DZ ₂ is connected between the cathode and gate of the thyristor Th ₂ . And the connection point of diodes D ₁ and D ₂ and the connection point of diodes D ₃ and D ₄
are mutually connected to the connection point through a resistor R ₁ , and a semiconductor switch 11 is constituted by each part of the thyristors Th ₁ , Th ₂ to the resistor R ₁ . In this semiconductor switch 11, the terminal _t1 connected to the anode side of the thyristor _Th1 now has a positive potential with respect to the terminal _t2 connected to the anode side of the thyristor _Th2 , and this potential breaks down the Zener diode _DZ1. When the level is reached, the gate of terminal t ₁ → diode D ₃ → resistor R ₁ → diode D ₂ → Zener diode DZ ₁ → thyristor Th ₁ →
A gate current flows through the thyristor Th ₁ through the path from the cathode to the terminal t ₂ , and the thyristor Th ₁ becomes conductive.
Also, when the terminal t ₂ becomes a positive potential with respect to the terminal t ₁ and this potential reaches a level that breaks down the Zener diode DZ ₂ , the terminal t ₂ → diode D ₁
→ Resistor R ₁ → Diode D ₄ → Zener diode DZ ₂ → Gate/cathode of thyristor Th ₂ → Gate current flows through thyristor Th ₂ through the path of terminal t ₁ , making this thyristor conductive. In this way, the semiconductor switch 11 has a predetermined level or higher (Zener diode _DZ1 or _DZ2 ) between the terminals _t1 and _t2 at both ends.
When a voltage (above the level that causes a breakdown) is applied, it automatically becomes conductive and supplies power to the load.

Next, the operation of the above embodiment will be explained. When the circuit breaker 5 and the switch 7 are closed in FIG. 1, power is supplied from the power supply 2 to the load 3 through the circuit breaker 5, the voltage regulator 1, and the switch 7. In this case, the voltage adjustment operation of the voltage regulator 1 causes no voltage difference between the power supply side and the load side of the voltage regulator, so there is almost no voltage between both ends of the semiconductor switch 11. I won't join. Therefore, each thyristor Th ₁ and Th ₂ of the semiconductor switch 11 remains non-conductive.

If a short circuit occurs in the voltage regulator 1, the short circuit current is detected by the current transformer 10, first the disconnector 5 opens, and then the switch 7 opens. At this time, since the voltage is applied to both ends of the semiconductor switch 11 at the same time as the shredder or disconnector 5 opens, the semiconductor switch 11 immediately becomes conductive due to the above-described operation. Therefore, power can be supplied to the load 3 through the semiconductor switch 11 immediately after the disconnector 5 is opened, and a power outage to the load can be prevented.

When the voltage on the load side drops and the voltage regulator 1 is about to switch taps, a difference occurs between the voltage on the power supply side of the voltage regulator and the voltage on the load side. appears across voltage regulator 1. Therefore, the Zener diode in Figure 3
The Zener voltage of DZ ₁ and DZ ₂ is the semiconductor switch 11
Set the thyristor so that it does not conduct even if the voltage across all taps is applied to the thyristor.

In the above embodiment, the present invention is applied to a single-phase automatic voltage regulator, but the present invention is not limited to single-phase, but can be applied to voltage regulators for circuits with any number of phases. The disconnector 5 and the switch 7 may be of any type as long as they have an opening/closing function that can fulfill the prescribed duties, and in addition to the normal mechanical type, they may also be of the type using a vacuum valve or a semiconductor switch. What I used, etc.
Any format may be used.

Although thyristors Th ₁ and Th ₂ are each shown as a single element in Fig. 3, multiple thyristor elements may be connected in parallel to increase the current capacity, or multiple thyristors may be used to increase the withstand voltage. Of course, the elements can be connected in series. Also, thyristor Th ₁ ,
Th ₂ is SCR (reverse blocking 2-terminal thyristor), SSS
It may be any silicon-controlled rectifying element such as (bidirectional two-terminal thyristor) or Triac (bidirectional three-terminal thyristor).

As described above, according to the present invention, in a voltage regulator in which a shield breaker and a switch are provided on the power supply side and load side of a voltage regulator, the power supply side terminal of the shield breaker and the load side terminal of the switch are provided. A semiconductor switch with a self-conducting function is installed across the line, so if the voltage regulator is disconnected from the line if necessary, the semiconductor switch is instantly made conductive at the same time as the disconnection, and power is supplied to the load side. This makes it possible to eliminate load power outages and ensure reliability of power supply. Further, since there is no need to control the semiconductor switch, the disconnector, and the opening operation of the switch, the control circuit can be simplified and reliability can be improved.

[Brief explanation of drawings]

FIG. 1 is a single line diagram schematically showing the configuration of an embodiment of the present invention, FIG. 2 is a connection diagram schematically showing only the configuration of the main parts of an example of a voltage regulator, and FIG. FIG. 2 is a connection diagram showing an example of the configuration of a semiconductor switch used in the present invention. 1... Voltage regulator, 5... Line breaker, 7... Switch, 9... Control circuit, 11... Semiconductor switch,
Th ₁ , Th ₂ ... Thyristor, D ₁ to _{D 4} ... Diode, DZ ₁ , DZ ₂ ... Zener diode, R ₁ ...
Resistor.

Claims (1)

[Claims] 1. A voltage regulator in which a tap selection switch for selecting a tap of a regulating transformer is a thyristor switch; A switch provided to open and close between the voltage regulator and the load side line, and a switch connected between the power supply side terminal of the shield breaker and the load side terminal of the switch, An automatic voltage regulator comprising a semiconductor switch that becomes self-conducting when both the switch and the switch are open-circuited.