JP2024019783A - automatic voltage regulator - Google Patents

Abstract

[Problem] To provide an automatic voltage regulator that can suppress product costs and correct voltage imbalance by controlling each phase.
SOLUTION: Voltage regulating transformers 9 and 10 are V-connected and inserted between three-phase distribution lines 1 to 3. Tap selectors 7b and 8b are connected to the indirect circuit sides of the voltage regulating transformers 9 and 10. Further, series transformers 4 to 6 connected in series with Y are inserted into the three-phase distribution lines 1 to 3. Switching switches 7a and 8a are connected to the indirect circuit sides of the series transformers 4 to 6. This constitutes tap changers 7, 8 consisting of tap selectors 7b, 8b and switching switches 7a, 8a, and connects the indirect circuit side of voltage regulating transformers 9, 10 and the indirect circuit side of series transformers 4 to 6. Connect the circuit sides. The tap changers 7 and 8 are individually controlled by a control section (not shown).
[Selection diagram] Figure 1

Description

The present invention relates to an automatic voltage regulator that can individually adjust the voltage of each phase of a three-phase power distribution line while suppressing product costs.

The voltage on power distribution lines constantly fluctuates due to increases and decreases in load. An automatic voltage regulator (hereinafter referred to as SVR) is a device that is connected to high-voltage distribution lines and suppresses voltage fluctuations.

SVR is roughly composed of a tapped voltage adjustment transformer, a tap changer, and a control unit.The control unit detects deviations from a preset reference voltage and operates the tap changer to always maintain the optimum voltage. It has a function to adjust to tap voltage.

The SVR tap changer generally consists of a changeover switch and a tap selector. As switching switches, there are types that switch contacts in insulating oil (submerged switch type) and types that open and close contacts in a vacuum valve (vacuum valve switch type).

In the oil submerged switch system, the insulating oil is contaminated by carbon sludge generated by arcing during switching, so the insulating oil needs to be replaced every 10 years or so when the tap switching operation exceeds 100,000 times. On the other hand, with the vacuum valve switch method, the contacts are inside the vacuum valve, so there is no contamination of the insulating oil. Therefore, there is an advantage that there is no need to replace the insulating oil, and in recent years, there have been many cases where this method has been adopted (see Non-Patent Document 1 below).

Aichi Electric Technical Report No. 36p3-6 Automatic voltage regulator and actuator Figure 3_ Vacuum valve type tap changer

FIG. 3 shows an example of a connection diagram of the above-mentioned SVR and three-phase distribution line. In the SVR, switching switches 101a to 101c are connected in series to terminals U, V, and W on the input side of each distribution line of a three-phase distribution line, and tap selectors 102a to 102c are connected to each switching switch 101a to 101c, respectively. has been done. The tap selectors 102a to 102c are connected to tapped voltage regulating transformers 103a to 103c, and the voltage regulating transformers 103a to 103c connect the Y-connected windings 104a to 104c to outputs of three-phase distribution lines. Connected to side terminals u, v, w.

Each switching switch 101a to 101c is equipped with a contact that opens and closes in insulating oil or vacuum, and by interlocking with tap selectors 102a to 102c arranged in each phase, tap selection can be performed while a load is applied. The taps of the transformers 103a to 103c are switched by the transformers 102a to 102c to suppress fluctuations in the output side distribution line voltage. The switching switches 101a to 101c and the tap selectors 102a to 102c constitute a tap changer, and the tap change by the tap changer is controlled by a control section (not shown).

However, since the SVR shown in FIG. 3 is originally a device based on three-phase balance, the control section constituting it controls the switching switches 101a to 101c and the tap selectors 102a to 102c for each phase. I can't. In other words, since the control section can only perform three-phase collective control, if voltage unbalance occurs between the phases, it cannot be suppressed.

Further, since the switching switches 101a to 101c are directly connected to the power distribution line, the contacts forming the switching switches 101a to 101c need to have the ability to turn on and off a large current. Therefore, there is a problem that the contact inevitably becomes larger and more expensive. In particular, when a vacuum valve switch method is applied to the switching switches 101a to 101c, the cost increases significantly since contamination of the insulating oil can be prevented.

The present invention has been made to solve these problems, and provides an automatic voltage regulator that can correct voltage imbalance by controlling each phase while suppressing product costs.

The invention according to claim 1 includes: a voltage regulating transformer inserted between lines of a three-phase distribution line and V-connected; a tap selector connected to an indirect circuit side of the voltage regulating transformer; A series transformer inserted in series in a phase distribution line and Y-connected, and a switching switch connected to an indirect circuit side of the series transformer, and a tap changer is configured by the tap selector and switching switch. and an automatic voltage regulator that connects the indirect circuit side of the voltage regulating transformer and the indirect circuit side of the series transformer by the tap changer, and further includes a control unit that controls the tap changer. The present invention is characterized in that the control unit controls a tap changer to adjust the voltage of the three-phase distribution line.

The invention according to claim 2 is characterized in that, in the automatic voltage regulator according to claim 1, the control unit controls the tap changer for each phase, thereby making it possible to adjust the voltage for each phase individually. .

The invention according to claim 3 is characterized in that, in the automatic voltage regulator according to either claim 1 or claim 2, the switching switch is equipped with a vacuum valve that opens and closes the contacts in a vacuum. .

According to the invention described in claim 1, since the contacts constituting the switching switch are connected to the secondary side of the series transformer, the current value at which the contacts open and close can be selected according to the capacity of the contacts, and the contacts can be made smaller. Moreover, it can be constructed at low cost.

According to the invention set forth in claim 2, since the tap changer can be controlled for each phase by the control section, it is possible to correct three-phase unbalance.

According to the invention set forth in claim 3, by applying the vacuum valve switch method to the switching switch, in addition to the effects set forth in claims 1 and 2, contamination of the insulating oil can be prevented, and there is no need to replace the insulating oil. Become.

FIG. 3 is a circuit diagram of an automatic voltage regulator of the present invention. (a) is a vector diagram showing each phase control by the automatic voltage regulator of the present invention, and (b) is a circuit diagram showing voltage values applied to each part of the automatic voltage regulator. FIG. 1 is a circuit diagram of a conventional automatic voltage regulator.

An embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a circuit diagram showing an automatic voltage regulator A of the present invention, which is generally called an SVR (Step Voltage Regulator). As shown in FIG. 1, the automatic voltage regulator A of the present invention is connected between input side terminals U, V, W and output side terminals u, v, w of three-phase distribution lines 1, 2, 3.

The automatic voltage regulator A includes series transformers 4, 5, and 6 connected in series to the distribution lines 1, 2, and 3, voltage regulating transformers 9, 10, and voltage regulating transformers connected in parallel to the distribution lines 1, 2, and 3, It is comprised of tap changers 7, 8 that connect the series transformers 4, 5, 6 and voltage regulating transformers 9, 10, and a control section (not shown) that controls the tap changers 7, 8.

The tap changer 7 includes a switching switch 7a and a tap selector 7b, and the tap changer 8 includes a switching switch 8a and a tap selector 8b. The tap selectors 7b, 8b select which tap to operate from among the tap windings of the voltage regulating transformers 9, 10. The switching switches 7a, 8a switch the circuit to the tap selected by the tap selectors 7b, 8b while remaining energized.

A first voltage line 1a passing through the automatic voltage regulator A connects the input terminal U and the series transformer 4. The series transformer 4 is connected to the output terminal u by a first adjustment line 1b.

A second voltage line 2a passing through the automatic voltage regulator A connects the input terminal V and the series transformer 5. The series transformer 5 is connected to the output terminal u by a second adjustment line 2b.

A third voltage line 3a passing through the automatic voltage regulator A connects the input terminal W and the series transformer 6. The series transformer 6 is connected to the output terminal u by a third adjustment line 3b.

The series transformer 4 includes a primary winding 4a whose one end is connected to the switching switch 7a, and a secondary winding 4b which connects the first voltage line 1a and the first adjustment line 1b in series. The series transformer 4 generates an induced voltage in the secondary winding 4b according to the voltage applied to the primary winding 4a, and the induced voltage increases the voltage of the first adjustment line 1b with respect to the first voltage line 1a. boost or buck the voltage.

The series transformer 5 includes a primary winding 5a whose one end is connected to the other end of the series transformer 4 and whose other end is connected to the tap selectors 7b, 8b, a second voltage line 2a and a second adjustment line. 2b are connected in series. The series transformer 5 generates an induced voltage in the secondary winding 5b according to the voltage applied to the primary winding 5a, and the induced voltage increases the voltage of the second adjustment line 2b with respect to the second voltage line 2a. boost or buck the voltage.

The series transformer 6 has a primary winding that has one end connected to the switching switch 8a and the other end connected to the other end of the primary winding 4a of the series transformer 4 and one end of the primary winding 5a of the series transformer 5. A secondary winding 6b connects the third voltage line 3a and the third adjustment line 3b in series. The series transformer 6 generates an induced voltage in the secondary winding 6b according to the voltage applied to the primary winding 6a, and the induced voltage increases the voltage of the third adjustment line 3b with respect to the third voltage line 3a. boost or buck the voltage.

The series transformers 4, 5, and 6 are Y-connected. The induced voltage generated in the secondary windings 4b, 5b, 6b of the series transformers 4, 5, 6 has a magnitude corresponding to the turns ratio of the secondary windings 4b, 5b, 6b to the primary windings 4a, 5a, 6a. voltage is induced.

The switching switch 7a is connected within the tap changer 7 to a tap selector 7b. The switching switch 8a is connected within the tap changer 8 to a tap selector 8b. The switching switches 7a, 8a are equipped with one or more contacts and a current limiting resistor for switching between energization and interruption of the current flowing through the primary windings 4a, 6a. The current limiting resistor suppresses the circulating current (cross current) flowing within the switching switches 7a, 8a.

The contacts are those that open and close in insulating oil (submerged switch type) and those that open and close within a vacuum valve (vacuum valve switch type). In the oil-submerged switch system, the insulating oil is contaminated by the arc generated when the switch is opened and closed, so if you want to eliminate the burden of replacing contaminated insulating oil, a vacuum valve switch system is adopted.

The tap selector 7b is connected to the voltage regulating transformer 9, and selects the tap connected to the secondary winding 9b of the transformer 9 to switch the step-up/step-down width of the series transformers 4 and 5. .

The tap selector 8b is connected to the voltage regulating transformer 10, and selects the tap connected to the secondary winding 10b of the transformer 10 to switch the step-up/step-down width of the series transformers 5 and 6. .

Tap selectors 7b and 8b generally have movable contacts arranged for three phases in the longitudinal direction of the drive shaft, rotate the movable contacts around the drive shaft as the drive shaft rotates, and are installed on a flat insulating plate. It has a mechanical structure that moves to the position of the fixed contact corresponding to the selected tap while compressing the fixed contact from above and below.

The voltage regulating transformer 9 includes a primary winding 9a connected between the distribution lines 1 and 2, and a secondary winding 9b connected to a tap that is switched and operated by a tap selector 7b. The voltage between the power distribution lines 1 and 2 acquired by the primary winding 9a is induced in the secondary winding 9b in a magnitude corresponding to the turns ratio of the primary winding 9a and the secondary winding 9b.

The voltage regulating transformer 10 includes a primary winding 10a connected between the distribution lines 2 and 3, and a secondary winding 10b connected to a tap that is switched and operated by a tap selector 8b. The voltage between the power distribution lines 2 and 3 acquired by the primary winding 10a is induced in the secondary winding 10b in a magnitude corresponding to the turns ratio between the primary winding 10a and the secondary winding 10b.

The voltage regulating transformers 9 and 10 are V-connected, and the V-connected three-phase voltage is applied to the Y-connected series transformers 4, 5, and 6 as the regulated voltage of the voltage regulating transformers 9 and 10.

Next, the operation of the automatic voltage regulator A of the present invention will be explained. When the voltage of the distribution line fluctuates due to load fluctuation, an electrical signal output from a control unit (not shown) causes the tap changers 7, 8 to reduce the difference between the voltage on the input side of the distribution lines 1, 2, 3 and the reference voltage. Tap selection is performed by , and tap switching of voltage regulating transformers 9 and 10 is performed accordingly.

At this time, the tap changers 7 and 8 drive the respective switching switches 7a and 8a and the tap selectors 7b and 8b to individually control the adjusted voltage for each phase. Each regulated voltage is applied to the primary windings 4a, 5a, 6a of the series transformers 4, 5, 6, and the secondary windings 4b, 5b, 6b of the series transformers 4, 5, 6 are applied to the series transformers 4, 5, 6. A regulating voltage proportional to the turns ratio of ,5,6 is induced to bring the voltage of the distribution line closer to the reference voltage.

Since the magnitude of the adjusted voltage of the UV phase and VW phase shown in Fig. 1 is different by individual control of each phase, it is possible to apply three-phase unbalanced voltage to the series transformers 4, 5, and 6, and the three-phase unbalanced Enables voltage correction.

FIG. 2(a) is a vector diagram of the above-mentioned phase control, and the vector values of voltages shown in the diagram indicate voltage values applied to each part shown in FIG. 2(b). The regulated voltages (Vtapuv, Vtapvw) of the voltage regulating transformers 9, 10 are applied to the primary windings 4a, 5a, 6a of the series transformers 4, 5, 6, and the secondary windings of the series transformers 4, 5, 6 are applied. Adjustment voltages (VTapu, VTapv, VTapw) proportional to the turns ratio of the series transformers 4, 5, 6 are induced in the lines 4b, 5b, 6b, thereby adjusting the secondary voltage.

At this time, the vector directions of the regulated voltage Vtapuv and the secondary voltage V2uv of the voltage regulating transformers 9 and 10 and the regulated voltage Vtapvw and the secondary voltage V2vw are the same, and the phase difference θtapv between the regulated voltages is the magnitude of the secondary voltage. It becomes the same as the phase difference θv2v.

Then, in order to apply the regulated voltages (Vtapuv, Vtapvw) to the primary windings 4a, 5a, 6a of the series transformers 4, 5, 6 using Y-connection, the primary windings 4a, 5a of the series transformers 4, 5, 6 are connected. , 6a, the applied tap voltages (Vtapu, Vtapv, Vtapw) with the center of gravity of the triangle as the neutral point are applied to series transformers 4, 5, and 6, making it possible to adjust the voltage for each phase individually. Become. Note that the voltages that can be adjusted by the voltage adjustment transformers 9 and 10 are only Vtapuv and Vtapvw, and Vtapwu is a combination of both.

In the above-mentioned voltage adjustment by controlling each phase individually, the tap changers 7 and 8 are configured by connecting the indirect circuit sides of the voltage adjustment transformers 9 and 10 and the indirect circuit sides of the series transformers 4, 5, and 6. Therefore, the value of the current flowing through the primary windings 4a, 5a, 6a of the series transformers 4, 5, 6 can be selected in accordance with the capacity of the contacts. As a result, the contacts constituting each tap changer 7, 8 can be constructed in a smaller size and at a lower cost.

In particular, even if a vacuum valve switch method is adopted for the switching switches 7a and 7b for the purpose of preventing contamination of the insulating oil, the vacuum valves to be applied can be small and inexpensive, so automatic voltage regulators The cost increase can be suppressed as much as possible.

INDUSTRIAL APPLICATION This invention is utilized as a technique applied to the voltage regulator installed in a three-phase distribution line.

1 to 3 Three-phase distribution line 1a First voltage line 2a Second voltage line 3a Third voltage line 4 to 6 Series transformer 4b to 6b, 9b, 10b Secondary winding 7,8 Tap changer 7a, 8a, 101a, 101b, 101c Switching switch 7b, 8b, 102a, 102b, 102c Tap selector 9, 10, 103a, 103b, 103c Voltage adjustment transformer 104a, 104b, 104c Winding A Automatic voltage regulator

Claims (3)

A voltage regulating transformer inserted between the lines of a three-phase distribution line and V-connected, a tap selector connected to the indirect circuit side of the voltage regulating transformer, and a tap selector inserted in series in the three-phase distribution line. , comprising a Y-connected series transformer and a switching switch connected to the indirect circuit side of the series transformer, the tap selector and the switching switch constitute a tap changer, and the tap changer constitutes a tap changer. A control unit is provided which connects the indirect circuit side of the voltage regulating transformer and the indirect circuit side of the series transformer and controls the tap changer, and the tap changer is controlled by the control unit. , an automatic voltage regulator that adjusts the voltage of a three-phase power distribution line. 2. The automatic voltage regulator according to claim 1, wherein the control section controls the tap changer for each phase to enable individual voltage adjustment for each phase. 3. The automatic voltage regulator according to claim 1, wherein the switching switch includes a vacuum valve that opens and closes contacts in a vacuum.