Data processing: generic control systems or specific application – Specific application – apparatus or process – Electrical power generation or distribution system
Reexamination Certificate
1999-10-25
2003-03-25
Black, Thomas (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Electrical power generation or distribution system
C700S022000, C700S293000, C361S059000, C361S063000, C361S067000, C361S071000, C361S093100
Reexamination Certificate
active
06539287
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a distribution control system for identifying and isolating a fault section when a fault takes place on a distribution line.
2. Description of Related Art
FIG. 7
is a diagram showing a distribution system. In
FIG. 7
, reference symbols AS/S, BS/S, CS/S, DS/S and ES/S each designate a distribution substation; F
1
-F
9
each designate a distribution line led out of the distribution substation AS/S; F
10
-F
18
each designate a distribution line led out of the distribution substation BS/S; F
19
-F
26
each designate a distribution line led out of the distribution substation CS/S; F
27
-F
34
each designate a distribution line led out of the distribution substation DS/S; F
35
-F
43
each designate a distribution line led out of the distribution substation ES/S; and LS
1
-LS
18
each designate a tie switch for coupling two distribution lines. Although not shown in
FIG. 7
, a plurality of load break switches are interposed in each distribution line.
FIG. 8
is a block diagram showing a conventional distribution control system, in which the reference numeral
1
designates a distribution transformer of the distribution substation AS/S;
2
designates a secondary main breaker of the distribution transformer
1
; and
3
designates a secondary main bus of the distribution transformer
1
, from which the distribution lines F
1
and F
2
are drawn out.
Reference numerals
4
and
5
each designate a distribution feeder breaker;
6
-
11
each designate a no-voltage opened mode load break switch connecting in series two respective sections of the distribution lines F
1
and F
2
, distribution line F
1
including sections F
1
-
1
, F
1
-
2
, F
1
-
3
, and F
1
-
4
and distribution line F
2
including sections F
2
-
1
, F
2
-
2
, F
2
-
3
, and F
2
-
4
;
12
designates a tie switch for coupling the distribution lines F
1
and F
2
;
13
-
19
each designate a feeder terminal unit for monitoring a fault current or the like passing through one of the load break switches
6
-
11
and tie switch
12
, for notifying a substation remote terminal unit
20
of presence/absence information about the fault current, and for turning on and off the load break switches
6
-
11
and tie switch
12
in response to a control signal fed from the substation remote terminal unit
20
; and
20
designates the substation remote terminal unit for transferring to a control center
21
the presence/absence information about the fault current supplied from the feeder terminal units
13
-
19
, and for transferring to the feeder terminal units
13
-
19
the control signal supplied from the control center
21
.
The reference numeral
21
designates the control center for managing the distribution of the distribution substation AS/S;
22
designates an information collecting unit for carrying out transmission and reception of information;
23
designates a computer system for identifying a fault section from the presence/absence information supplied thereto, and for producing the control signal commanding to open the load break switches at both ends of the fault section; and A
1
-A
5
, B
1
-B
3
and C each designate a communication line.
FIG. 9
is a block diagram showing an internal arrangement of each of the load break switches
6
-
11
and feeder terminal units
13
-
18
. In
FIG. 9
, the reference numeral
31
designates a contact maker;
32
designates an operation rod for making or breaking the contact maker
31
;
33
designate an actuator of each of the load break switches
6
-
11
;
34
designates a current transformer for detecting a current flowing through the distribution line on the power supply side;
35
designates a control transformer for detecting a voltage on the distribution line on the power supply side; and
36
designates a control transformer for detecting a voltage on the distribution line on the load side.
The reference numeral
37
designates a voltage/phase angle detector connected to the control transformers
35
and
36
for detecting the voltage and phase on the distribution line;
38
designates a current detector connected to the current transformer
34
for detecting the current passing through each of the load break switches
6
-
11
;
39
designates a controller for monitoring an operation state of the switch actuator
33
and the current passing through each of the load break switches
6
-
11
, and for controlling the switch actuator
33
in response to the control signal fed from the substation remote terminal unit
20
;
40
designates a communication circuit for exchanging with the substation remote terminal unit
20
various information (such as values detected by the voltage/phase angle detector
37
and current detector
38
);
41
designates a battery for supplying power to component circuits of each of the feeder terminal units
13
-
18
in case of outage of the distribution line; and
42
designates a branch box for connecting the communication circuit
40
of each of the feeder terminal units
13
-
18
to a communication line.
Next, the operation of the conventional system will be described.
When controlling the distribution system of the distribution substation AS/S, the substation remote terminal unit
20
regularly transmits to the feeder terminal units
13
-
19
an information transmission request through the communication lines A
4
and A
5
so as to collect information about the load break switches
6
-
11
and tie switch
12
(including the presence/absence information of the fault current passing through the load break switches
6
-
11
).
On the other hand, the feeder terminal units
13
-
19
always collect information about the load break switches
6
-
11
and tie switch
12
, and send the information back to the substation remote terminal unit
20
through the communication lines A
4
and A
5
in response to the information transmission request sent from the substation remote terminal unit
20
.
The information about the load break switches
6
-
11
and tie switch
12
thus collected by the substation remote terminal unit
20
is transferred to the control center
21
. Thus, the information collecting unit
22
in the control center
21
receives the information, and the computer system
23
in the control center
21
identifies the fault section from the information about the load break switches
6
-
11
and tie switch
12
if a distribution line fault takes place.
Identifying the fault section, the computer system
23
in the control center
21
supplies the substation remote terminal unit
20
with a control signal that commands it to open the load break switches at both ends of the fault section. In response to the control signal, the substation remote terminal unit
20
transfers, to the feeder terminal units managing the load break switches at both ends of the fault section, the control signal commanding to open the load break switches. Thus, the feeder terminal units open the load break switches.
An example will now be described assuming that a distribution line fault takes place in the section F
1
-
3
of the distribution line F
1
as shown in FIG.
8
.
If a distribution line fault takes place in the section F
1
-
3
of the distribution line F
1
, a protective relay not shown in
FIG. 8
but included in the feeder breaker
4
operates so that the feeder breaker
4
trips and the distribution line F
1
is shut down. However, since the load break switches
6
-
8
are a no-voltage opened mode switch, they open immediately when the distribution line F
1
is shut down to a no-voltage state by the distribution line fault.
Counting about 60 seconds after breaking the distribution line F
1
, the feeder breaker
4
automatically closes again by the operation of an embedded reclosing relay. Accordingly, the power is supplied to the section F
1
-
1
, that is, to the power supply side of the load break switch
6
. After elapsing about seven seconds, the load break switch
6
automatically closes again so that the power is supplied to the section F
1
-
2
, that is, to the power sup
Barnes Crystal J
Black Thomas
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
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