JPS6149893B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for connecting the second group transformer to the first group transformer when the first group of AC/DC conversion tap transformers is in operation and the second group is in a stopped state. This article relates to a method for parallel input.

Generally speaking, in order to transmit large amounts of power in DC power transmission, it is most efficient to increase the voltage.For example, if the first group is 125KV DC and the second group is 125KV DC, if they are connected in series, the voltage will be 250KV DC. , large amounts of power can be transmitted using only two DC transmission power supplies. In this case, it is common to operate the first group and the second group at the same time, but when only the first group is in operation and the second group is stopped, the second group
The group may be arranged in parallel with the first group. (however,
Currently, in frequency converting stations, the first group and the second group are not connected in series in order to lower the insulation, but only the first group is used. ) Traditionally, in Japan, large amounts of power have not been transmitted through direct current transmission, such as the Hokkaido-Honshu interconnection, and only frequency conversion stations such as the Sakuma Frequency Converter Station and the Shin-Shinano Frequency Converter Station have existed. There was no need to parallelize the transformers as described above, but in foreign countries, after manually aligning the taps of the second group transformers with the taps of the first group transformers, the second group breaker was turned on. The second group is arranged in parallel with the first group.

This is because if the voltages of the first group transformer and the second group transformer are different, current will flow around on the alternating current side, which is undesirable.

However, the conventional parallel closing method is manual and therefore cumbersome to operate, and also has the problem that the transient overvoltage that occurs when closing the AC switch or disconnector is large and has a negative effect on the AC/DC converter.

The present invention aims to provide a parallel connection method that can automatically connect a group of tap transformers in a stopped state to a group of tap transformers in an operating state without having such conventional problems. It is.

The present invention requires that the tap setting of the transformer be the lowest voltage tap in order to reduce the effect of transient overvoltage that occurs when a disconnector connected to an AC/DC conversion transformer is turned on. It is preferable that the tap of the tapped transformer be turned to the lowest voltage tap when the AC transformer connected to the tapped transformer connected to the AC/DC converter opens. Therefore, when the second group of tap transformers is placed in parallel with the first group while the first group of tap transformers is in operation,
This was done in view of research findings that it is preferable to match the taps of the first and second group transformers after connecting them in parallel with the taps that minimize the voltage on the converter side of the second group of tapped transformers. It is.

That is, the present invention sets the second group of transformers to the lowest voltage tap, detects the difference between the taps of the first and second groups, and sets the second group of taps to the lowest voltage on the condition that the AC switch or disconnector is closed. The present invention provides a method for connecting transformers with taps for AC/DC conversion in parallel so that the taps are automatically matched to one group of taps.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an example of an AC/DC converter station. This figure shows two converter stations, A converter station and B converter station, but both have the same configuration.
Here, only the A converter station will be explained in detail.
In FIG. 1, the primary sides of the first group of converting tap transformers 3 and the second group of converting tap transformers 4 are connected to AC line breakers CB-11 and CB-21, respectively.
It is connected to the AC bus 2 and the AC system 1 via AC disconnectors LS-11 and LS-21.
The secondary sides of the first group and second group transformers 3, 4 are connected to the AC sides of AC/DC converters 5, 6, respectively.

The DC sides of the AC/DC converters 5 and 6 are connected to the DC reactor of the B conversion station via a DC reactor (DCL) 7, a high voltage DC transmission line 8, and a low voltage DC transmission line 9. In addition, in the figure, BPS-11, BPS-2
1 is a bypass switch that bypasses the converter;
DS-11, DS-12, DS-13, DS-21,
DS-22 and DS-23 are disconnectors on the DC side.

FIG. 2 shows the opening/closing status of the first group of AC disconnectors, AC disconnectors, bypass switches, and DC disconnectors in various operating modes shown in FIG. 1. In the disconnected mode, the DC disconnector DS-13 is closed, all other switches are open, and the gate control of the converter is also GB (gate block).
In the stop mode, AC disconnector LS-11, DC disconnector
DS-11, DS-12, bypass switch BPS-
11 is closed, and the DC disconnector DS-13 is opened to bring the converter into a state in which voltage can be applied, that is, a state in which preparation for startup is completed. In this case, the gate control is GB. Bypass switch in floating form
Open BPS-11 and insert AC cutter CB-11. In this state, gate control is GB.
In the deblock mode, all the switches are in the same state as floating, but the gate control is DEB (deblock), and the switches are switched from A converter station to B converter station or B
Power can be exchanged from the conversion station to the A conversion station.

To align the second group with the first group from a state in which the first group is deblocking and the second group is in a disarranged state, the second group is first brought to a stopped state. In other words, the DC disconnector DS-23 in Figure 1 is closed, the DC disconnector DS-21, DS-22, and the bypass switch BPS are closed.
-21, change the AC disconnector LS-21 from open to close,
Then open the DC disconnector DS-23. Next, the AC disconnector CB-21 is turned on, a BPP (bypass pair) command is given to the second group of AC/DC converters 6 to make this converter 6 conductive, and then the bypass switch is turned on.
Open BPS-21. Next, a DEB command is issued to the AC/DC converter 6 of the second group, which causes the first and second groups to
The group will operate in parallel.

FIG. 3 is a block diagram illustrating one embodiment of the method of the present invention. First, as shown in block B1, the tap position of the first group of transformers 3 in the operating state is detected, and as shown in block B2, the tap position of the second group of transformers 4 in the stopped state is detected at the lowest voltage. Make sure to tap it. Then, as shown in block B3, the two tap positions are compared, and if a tap shift is detected, the AC disconnector CB-21 is turned on (block B4).
At the same time, a command is issued to raise the tap on transformer 4 (in the direction in which the voltage increases) (block B7),
When the tap has increased, it is again compared with the tap of the transformer 3, and if a tap deviation is detected again, a command to raise the tap of the transformer 4 is issued. By configuring a closed loop in this way, a command to raise the tap of the transformer 4 is issued until there is no deviation between the tap of the transformer 3 and the tap of the transformer 4.

FIG. 4 is an example of an apparatus for carrying out the method of the invention shown in FIG. In FIG. 4, between a DC positive power supply bus P and a DC negative power supply bus N, a tap changeover mechanism dial switch 10 of the transformer 3 shown in FIG. 1, a tap changeover mechanism dial switch 11 of the transformer 4 shown in FIG. An auxiliary relay for displacement detection is connected in series. In addition, AC positive power supply bus R
and the AC negative power supply bus T are the auxiliary contact 13 of the AC shield breaker CB-11 shown in Fig. 1, the auxiliary b contact 14 of the AC shield breaker CB-21, and the auxiliary relay 1.
Time-limited return relay 12b that opens when 2 is energized.
and a motor 15 for raising or lowering the tap of the tap transformer are connected in series. In FIG. 3, when the positions of dial switches 10 and 11 match, auxiliary relay 12 is energized and time-limited return relay 12b is opened. In addition, auxiliary contacts 13, 1
4 is closed, and if the time-limited return relay 12b is closed, the motor winding is energized, the motor is energized, and the tap of the transformer is switched.

In addition, in this example, 13 and 14 are AC switches and disconnectors.
Although the auxiliary contacts 13 and 14 of the CB are used, the auxiliary contacts of the AC disconnector LS or the DC disconnector DS may be connected in series with the auxiliary a contact of the AC disconnector CB.

FIG. 5 shows another example for carrying out the method of the invention shown in FIG. In this example, a contact 16 that closes when a BPP (bypass pair) command is issued is connected in series to the circuit in Figure 4b, and while the first group in Figure 1 is in operation, the second When the group is in the floating form shown in Table 1, the tap of the transformer is switched when a BPP command is issued to the AC/DC converter 6. That is, when the auxiliary contacts 13 and 14 are closed, the contact 12b is closed, and the contact 16 is closed, the motor 15 is energized and the tap of the transformer is switched.

In addition, in the above explanation, it was assumed that the taps of the transformers of the first group match the taps of the transformers of the second group, but the taps of the transformers of the second group
It goes without saying that the tap of the transformer of the first group may be made to match the lowest voltage tap of the group.

As is clear from the above description, the present invention provides a first group transformer that is in operation and a second group transformer that is in a stopped state.
When connecting group transformers in parallel, first set the second group transformer to the lowest voltage tap, detect the tap deviation between the first group transformer and the second group transformer, and connect to the second group transformer. Since the taps of the first group transformer and the second group transformer are made to match on the condition that the AC switch or disconnector is turned on, the transient that occurs when the AC switch or disconnector is turned on is This has the effect of minimizing the effect of overvoltage on the AC/DC converter, and also has the advantage that the taps can be automatically adjusted, significantly reducing the burden on the operator.

[Brief explanation of the drawing]

Figure 1 is an electrical wiring diagram showing an example of the configuration of a general AC/DC converter station, and Figure 2 is a diagram showing the first group of disconnectors, line disconnectors, and bypass switches in various operating modes of the AC/DC converter station shown in Figure 1. FIG. 3 is a block diagram showing an embodiment of the parallel input method according to the present invention, and FIG. 4 is a diagram showing the method of the present invention shown in FIG. 3. 5 is an electrical wiring diagram showing another example of the apparatus for carrying out the method of the present invention shown in FIG. 3. FIG. 1... AC system, 2... AC bus, 3... 1st group conversion tap transformer, 4... 2nd group conversion tap transformer, 5, 6... AC/DC converter, CB-11, CB
-21...AC switch, LS-11, LS-21...
AC disconnector, BPS-11, BPS-21...Bypass switch, DS-11, DS-12, DS-13,
DS-21, DS-22, DS-23...DC and disconnectors.

Claims (1)

[Claims] 1. When the first group of tap transformers for AC/DC conversion is in an operating state and the second group is in a stopped state, the transformers of the second group are arranged in parallel with the transformers of the first group. In the parallel input method, the second group of transformers is set to the lowest voltage tap, the tap deviation between the first and second group transformers is detected, and the AC connected to the second group transformers is A method for parallel connection of transformers with taps for AC/DC conversion, characterized in that the taps of the first group of transformers and the taps of the second group of transformers are made to match on the condition that a disconnector is connected. . 2. In the parallel input method of paralleling the transformers of the second group with the transformers of the first group when the first group of AC/DC tap converters is in an operating state and the second group is in a stopped state, The transformer in the group is set to the lowest voltage tap, the tap shift between the transformers in the first group and the second group is detected, and the AC circuit breaker connected to the transformer in the second group is turned on. For AC/DC conversion, the taps of the first group of transformers are made to match the taps of the second group of transformers on the condition that a bypass pair command is issued to the AC/DC converter. How to connect transformers with taps in parallel.