JP2843364B2 - Switching method for low-voltage side of distribution transformer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for switching a low-voltage side of a transformer.

[Prior Art] With the development of an advanced information society, demands for stable supply of electric power are increasing. In addition, it is becoming difficult year after year for the power outage of the construction, and it is proposed and implemented that the construction be performed without causing the power outage of the customer. For example, as shown in FIG. 3, when replacing the pole transformer Trb of one of the banks B of the banks A and B, the load LB of the bank B is switched to the bank A and the construction of the bank B is performed. Power is supplied from the bank A to the load LB of the bank B, and the load LB is switched back to the bank B after the construction is completed.

As a method of switching the load LB of the B bank to the A bank, a low voltage switch LS connected to the low voltage side of the B bank and capable of opening and closing all three phases collectively corresponds to the case where the load side becomes no voltage. Opening / closing part is automatic in three phases at once (10ms
(within ec) by connecting a switching switch S1 that closes
Switching switch S2 of the same configuration as above for branching of both B banks
After connection, there is a method of performing switching according to the following operation.

1. Turn ON the switch S1 manually. 2. Turn off the low-voltage switch LS by manual operation. 3. Turn off the switching switch S1 manually. 4.Switch S
2 detects that the load LB side has become no voltage, and instantaneously (10 /
(within msec), and the current IA flows from the bank A to the load LB side.

[Problems to be Solved by the Invention] However, in the above method, the secondary side (low voltage side) of the transformer is used.
Therefore, there is a problem that this method cannot be performed in a system without a low-voltage switch (low-voltage branch box) on the low-voltage side of the transformer. Also,
There is a problem in that two switching switches are required, and it takes time to connect the switching switches and to remove them after the construction is completed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a system that does not have a low-pressure switch (low-pressure branch box) on the low-pressure side of a transmission.
It is an object of the present invention to provide a low-voltage side switching method of a distribution transformer that requires only one unit and that can perform load switching instantaneously.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for switching the load of two low-voltage distribution lines connected to a high-voltage distribution line via a primary cutout and a transformer, respectively. In the transformer low-voltage side load switching method performed while ensuring phase synchronization and coordination, between the phases of the two low-voltage distribution lines, when no voltage of one of the low-voltage distribution lines is detected, the phase between those phases is detected. And a backup power supply circuit for supplying power to each low-voltage side phase of the load-side distribution transformer that is to be set to no voltage during the period from the detection of no voltage to the connection between the phases. When connecting the equipment and switching the load on one low-voltage distribution line to the other low-voltage distribution line, identify the primary cutouts connected to each high-side phase of the load-side distribution transformer that is to be de-energized. One by one The gist is to release them next.

[Operation] Therefore, a switching device is connected between each phase of both low-voltage distribution lines, and the primary cutout of one low-voltage distribution line is opened. When the switching device detects no voltage, the standby power supply circuit supplies power until the switch of the device is turned on, and thereafter, the standby power supply circuit stops supplying power after the switch is turned on. Switching of the load is performed.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a primary cutout PC is connected to each of the phases U, V, and W to the distribution line L on the high voltage side of the transformers Tra and Trb provided in both banks A and B. . A switching device Y is connected via a bypass cable K between the low voltage sides of both the A and B banks.

As shown in FIGS. 1 and 2, in the switching device Y, the respective phases U, V, and W of both distribution lines L are connected by bypass cables K, and the bypass cables K are always open. Switches SU, SV, and SW are provided. A first compensation circuit Q1 is connected between the U and V phases of the bypass cable K on the B bank side of the switches SU, SV and SW, and the bypass cable K is connected on the B bank side of the switches SV and SW. The second compensating circuit Q2 is connected between the U and W phases.

In the two compensation circuits Q1 and Q2, there are provided detection circuits 1 for detecting no voltage between the U and V phases and between the V and W phases on the B bank side, respectively. Circuits 3 are respectively connected. The high-speed changeover switch circuit 2 is configured by a non-contact element such as a thyristor. The detection circuit 1 outputs a detection signal to the high-speed changeover switch 2 and the drive circuit 3 when detecting no voltage on the B bank side.

The drive circuit 3 of the first compensation circuit Q1 has relays MCU, MC
V is connected, and a relay MCW is connected to the drive circuit 3 of the second compensation circuit Q2.

The drive circuit 3 of the compensation circuit Q1 shown in FIG. 1 drives and controls the relays MCU and MCV based on the detection signal of the detection circuit 1, and the drive circuit 3 of the second compensation circuit Q2.
Drives the relay MCW based on the detection signal of the detection circuit 1. And this relay MCU,
MCV and MCW open and close the switches, SU, SV and SW, respectively, and output a closing signal to each delay circuit 5.

A power supply circuit 4 as a standby power supply circuit is connected to the high-speed changeover switch circuit 2. In the power supply circuit 4, a charging circuit (not shown), a battery, a well-known tuning circuit, and an inverter circuit are incorporated. When the distribution line L on the side has no voltage, the power is instantaneously and temporarily supplied from the power supply circuit 4 to the load LB side of the B bank through the high-speed switch circuit 2 while ensuring the coordination of the voltage and the phase. It has become.

When power is supplied from different banks in this way, it is a well-known matter to cooperate in voltage and phase.

Further, the relays MCU, MC
While turning on the switches SU, SV, SW via V, MCW,
An input signal is input to the delay circuit 5. Each of the delay circuits 5 is a high-speed changeover switch circuit 2 after the switches SU, SV, and SW are turned on.
, The supply of power to the load LB on the B bank side by the battery is stopped, and charging of the battery is started.

Next, a case where the load LB of the B bank is switched to the A bank will be described.

First, the primary cutout on the high pressure side of bank B
Open PCs sequentially. That is, distribution line L of bank B
Release the U-phase primary cutout PCU. Then, there is no voltage between the U and V phases of the distribution line, and the first compensation circuit Q1
Detection circuit 1 detects this, and the high-speed changeover switch circuit 2
And a detection signal to the drive circuit 3.

The high-speed changeover switch circuit 2 supplies an output between the U and V phases of the distribution line L of the B bank by the battery, tuning circuit and inverter circuit of the power supply circuit 4 based on the detection signal. On the other hand, the drive circuit 3 drives and controls the relays MCU and MCV based on the detection signal of the detection circuit 1 to turn on the switches SU and SV.

The delay circuit 5 switches the high-speed switching circuit 2 after a predetermined time based on the input command signal of each drive circuit 3 to stop the supply of power to the U- and V-phase load LB on the B bank side by the power supply circuit 4. , The state of the power supply circuit 4 is switched.

Therefore, power is supplied between the low-voltage side U and V phases of the bank B from the low-voltage side U and V phases of the bank A.

Next, when the primary cutout PCV of the bank B is released, there is no voltage between the low-voltage side V and W phases of the bank B. Therefore, the detection circuit 1 of the second compensation circuit Q2 detects this non-voltage. The high-speed changeover switch circuit 2 is switched to supply power between the low voltage side V and W phases of the B bank by the battery, tuning circuit and inverter circuit of the power supply circuit 4.

In addition, the switch S is connected to the drive circuit 3 via the relay MCW.
Complete the W input. On the other hand, after a predetermined time, the delay circuit 5
V, W by power supply circuit 4 via high-speed changeover switch circuit 2
The supply of power to the inter-phase load LB is stopped, and the power supply circuit 4 is switched to a charged state.

Therefore, electric power is supplied between the low-voltage side V and W phases of the bank B from the low-voltage side V and W phases of the bank A.

Finally, when the W-phase primary cutout PCW is released, the operation of switching the load LB of the B bank to the A bank is completed.

Therefore, in the above switching method, unlike the conventional method, there is no need to provide two switching switches, and the number of switching devices Y can be reduced to one, and the present invention can be applied to a system without a low-voltage switch. .

Further, since the compensation circuits Q1 and Q2 are provided in the switching device Y and the power is supplied from the battery until the switches SU, SV and SW are turned on, it is possible to perform complete instantaneous interruption switching. Further, since the switches SU, SV, and SW are turned on for a very short time, the capacity of the compensation circuits Q1 and Q2 can be small.

Further, in the present embodiment, the load switching is performed from the U phase, but the switching device Y may be configured to perform the load switching from the W phase.

In the present embodiment, single-phase compensation is performed by the two compensation circuits Q1 and Q2. However, it is also possible to configure the compensation circuit in a three-phase system and use only one compensation circuit.

Note that the present invention is not limited to the above-described embodiment, and can be arbitrarily changed without departing from the spirit of the present invention.

[Effects of the Invention] As described above in detail, according to the present invention, even in a system without a low-voltage switch (low-voltage branch box) on the low-voltage side of the transformer, the load of one bank can be switched to the other bank. it can.
In addition, since only one switching device is required at the time of the switching operation, the labor of connecting the switching device and removing it after the completion of the construction is reduced.

Further, since the supply of power to one bank is compensated by the compensation circuit until the switch is completely turned on, the load can be switched instantaneously.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is an electric circuit diagram showing a state in which a switching device is connected between both banks. FIG. 2 is a circuit configuration in the switching device. FIG. 3 is an electric circuit diagram showing a conventional method. A, B …… Bank, SU, SV, SW …… Switch, PC, PCU, PCV, PC
W: Primary cutout, Y: Switching device, LA,
LB: Load, Q1, Q2: Compensation circuit.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masayoshi Ito 1st character small needle in Inuyama City, Aichi Prefecture Energy Support Corporation (72) Inventor Hiroshi Watanabe 1st character small needle in Inuyama City, Aichi Prefecture Energy Support Corporation ( 58) Field surveyed (Int.Cl. ⁶ , DB name) H02J 3/00-5/00

Claims (1)

(57) [Claims] 1. A low-voltage side of a transformer for switching loads of two low-voltage distribution lines connected to a high-voltage distribution line via a primary cutout and a transformer, respectively, while ensuring voltage and phase synchronization and coordination. In the load switching method, between the phases of the two low-voltage distribution lines, a switch that connects between the phases when detecting no-voltage of one of the low-voltage distribution lines, from the detection of the no-voltage to the connection between the phases. A switching device having a backup power supply circuit for supplying power to each phase on the low voltage side of the distribution transformer on the load side which is to be set to no voltage, and connecting the load on one low voltage distribution line to the other low voltage. A low-voltage side load switching method for a transformer in which, when switching to a distribution line, primary cutouts connected to the respective high-side phases of a load-side distribution transformer to be set to no voltage are sequentially opened one by one.