JPH10248159A - Method and system for protection of spot-network receiving installation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protective system which can prevent a protector breaker from being opened unnecessarily, which can supply electric power stably and whose supply reliability can be increased. SOLUTION: Network relays are used for a network receiving installation in which a plurality of distribution lines 1a, 1b and a network bus 5 are connected by network circuits 4a, 4b provided with protector breakers 8a, 8b. The network relays are mounted on the network circuits 4a, 4b and output respective opening instructions to the protector breakers 8a, 8b when the network circuits 4a, 4b are in a reverse-power and overcurrent state. Current transformers 20a, 20b are installed on the distribution lines 1a, 1b on the side of a power supply near branch points to the network circuits 4a, 4b from the distribution lines 1a, 1b. When electric power in their positions is large, power relays 21a, 21b are actuated, and current-phase relays 22a, 22b are actuated when a current phase is 'capacitive'. When not the power relays 21a, 21b but the current phase relays 22a, 22b are actuated, the protector breakers 8a, 8b are opened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a system for protecting a power receiving equipment for a spot network for supplying electric power to an electric load for a building and the like, and more particularly to a control of opening and closing of a protector circuit breaker installed in a network line. .

[0002]

2. Description of the Related Art FIG. 7 shows an example of a conventional protection system. As shown in the figure, two distribution lines 1a, 1b
Are connected to commercial power sources 3a and 3b via distribution line breakers 2a and 2b, respectively. And each distribution line 1a,
1b is branched into network lines 4a and 4b at a predetermined position, and is connected to a network bus 5.

Each of the network lines 4a and 4b includes a primary switch 6a and 6b inserted in series between the distribution lines 1a and 1b and the network bus 5, a network transformer 7a and 7b, and a protector breaker 8a. , 8b (the primary switches 6a, 6b are on the distribution lines 1a, 1b side), and by controlling the switching of the switches 6a, 6b, 8a, 8b, the individual network lines 5a, 5b are connected to the distribution line 1
a and 1b and the network bus 5 and are disconnected.

In an emergency such as a planned power outage, a short circuit accident, or a ground fault accident, the protector circuit breakers 8a and 8b are opened to protect a healthy circuit. The open / close control of the protector circuit breakers 8a and 8b is performed by monitoring the current / voltage state of the series circuit. In other words, network current transformers 9a, 9b and instrument transformers 10a, 10b are provided between the network transformers 7a, 7b and the protector breakers 8a, 8b, and their detection outputs are connected to the network relays 11a, 11b.
To give to. This network relay 1
Reference numerals 1a and 11b denote a reverse power detection function for detecting that a current flows reversely (the polarity of the voltage is reversed) based on given voltage information, and a network line 4 based on the current information.
It has an overcurrent detection function of detecting that the value of the current flowing through a and 4b is excessive. Then, when a predetermined state is detected by each detection function, control is performed to open the protector breakers 8a and 8b. Of course, when it becomes normal, the protector circuit breakers 8a and 8b are turned on again and the process of returning is performed.

[0005] As is apparent from the figure, the distribution line 1
a and the distribution line 1b are connected via each of the network lines 4a and 4b and the network bus 5, but due to the potential difference between the parts, a current flows from the distribution line 1a to the network bus 5 via the network line 4a ( Power is supplied), a current flows (is supplied with power) from the distribution line 1b to the network bus 5 via the network line 4b, and no backflow occurs.

Reference numeral 15 denotes a private generator.
In this example, it is always operating, and power is also supplied to the network bus 5 from the private generator 15. In addition, the main circuit breaker 16 and the main transformer 1 are connected to the distribution line 1a.
7 and a regular standby power receiving line 19 using a distribution line 1a provided with an instrument transformer 18 as a regular line. In addition, the regular standby power receiving line 19 uses the distribution line 1b as a backup line, and the main transformer 17 can be connected to the distribution line 1b via the main circuit breaker 16 '. As is well known, the main circuit breakers 16, 16 'are opened and closed in synchronization with each other, and when one is open, the other is closed. 1
a or 1b to receive power supply.

[0007] The operation in an emergency or the like will be briefly described. If a planned power outage occurs for inspection of the distribution line 1a, or if a ground fault or short circuit accident occurs in the distribution line 1a, the distribution line 1a will be described. Reverse power is generated from 1b to the distribution line 1a via the network line 4b → the network bus 5 → the network line 4a.

[0008] In case of rolling blackout and ground fault,
Since the distribution line breaker 2a is opened, the power supply from the commercial power supply 3a to the distribution line 1a is stopped, so that the reverse power is transmitted from the healthy distribution line 1b to the network line 4a via the above-described path. Flows. Therefore, the reverse power is detected by the reverse power detection function of the network relay 11a, and a detection signal is output. Then, based on the detection signal, control is performed such that the protector circuit breaker 8a is opened after a lapse of a predetermined set time. Thereby, after that, no current flows into the distribution line 1a, and the distribution line 1a can be separated from the healthy line (the distribution line 1b).

When a short-circuit fault occurs in the distribution line 1a, a short-circuit current flows in the opposite direction toward the short-circuit fault point via the above-mentioned path, and the function of the power equipment connected to the network lines 4a and 4b is reduced. Adversely affect In such a case, since a relatively large current flows in the reverse direction, the reverse power detection function and the overcurrent detection function of the network relay 11a can be detected simultaneously. Therefore, when the detection signal is output from both functions, the protector breaker 8a is instantaneously opened. As a result, adverse effects on the power equipment due to the short-circuit current are suppressed as much as possible, and the accident can be localized by disconnecting the distribution line 1a from the healthy line (the distribution line 1b).

[0010]

However, in the conventional protection method and system described above, when the protector breakers 8a and 8b originally provided in the respective network lines 4a and 4b must be closed, a high precision is required. There is a phenomenon that the detection output is made from the network relays 11a and 11b and the protector breakers 8a and 8b are opened.

That is, since the regular standby power receiving line 19 is connected to the distribution line 1a, a normal state (a state without planned power failure or accident) is obtained at the branch point between the distribution lines 1a and 1b and each of the network lines 4a and 4b. Causes a potential difference. If the spot network power receiving equipment has a light load, a reverse power flow may flow to the service backup power receiving line 19 via the distribution line 1b → the network line 4b → the network bus 5 → the network line 4a → the distribution line 1a. is there.

Then, since the reverse power flow generated at this time is a current flowing in the reverse direction for the network line 4a, the reverse power flow is detected by the reverse power detection function of the network relay 11a monitoring the network line 4a. In addition, there is a problem that the protector circuit breaker 8a is cut off after a lapse of a set time based on the detection output.

When a private generator 15 is connected to the network bus 5, the private generator 15
Are the distribution lines 1a, 1 from the respective network lines 4a, 4b.
b, it is linked to the commercial power supplies 3a, 3b. Therefore, when the magnitude of the generated power of the private generator 15 exceeds the load capacity in use, the power of the difference between the magnitude of the generated power and the load capacity in use is diverted to the network lines 4a and 4b as a reverse power flow. . As a result, the reverse power flow is detected by the reverse power detection function of the network relays 11a and 11b, so that the corresponding protector circuit breakers 8a, 8a,
8b is interrupted.

The present invention has been made in view of the above background, and has as its object to solve the above problems, prevent unnecessary opening of the protector breaker, and stably supply power. It is an object of the present invention to provide a spot network power receiving equipment protection method and a protection system capable of improving the supply reliability.

[0015]

In order to achieve the above object, in a method for protecting a spot network power receiving equipment according to the present invention, a plurality of distribution lines and a network bus are connected to each distribution line, and a primary switch and a network transformer are connected. A protection method used for network power receiving equipment connected by a network line having a switch and a protector breaker, wherein the protector breaker is opened based on a control signal from a network relay mounted on the network line. Detecting a power state on the distribution line near the branch point from the distribution line to the network line and on the power supply side, and shutting off the protector based on a detection result of the power state and an output of the network relay. The opening and closing of the vessel is controlled (claim 1).

As a protection system suitable for carrying out such a method, for example, a plurality of distribution lines and a network bus are provided for each distribution line by a network circuit having a primary switch, a network transformer, and a protector breaker. Used in the network power receiving equipment to be connected, a protection system that opens the protector breaker based on a control signal from a network relay mounted on the network line, wherein the protection line from the distribution line to the network line Power detection means for detecting a power state on the distribution line near the branch point and on the power supply side, and opening and closing control of the protector breaker based on a detection result of the power detection means and an output of the network relay; (Claim 5).

That is, when the load on the network line is light or when the amount of power generated by the private generator connected to the network bus is large, reverse power may be generated on the network line. In a normal state, power is supplied to the distribution line, and power is also generated on the power supply side from the branch point. Also, in the event of a planned power outage or a ground fault, reverse power is generated on the network line. However, in the case of a planned power outage or the like, no power is generated on the power supply side from the branch point. Therefore, the former normal state (the protector breaker is not opened) and the latter state in which the protector breaker should be opened can be discriminated by monitoring the state of the power on the power supply side from the branch point.

On the other hand, in the case of a short-circuit accident, reverse power is generated on the network line, and power may be generated on the power supply side from the branch point. However, in such a case, since the current flowing through the network line is large (overcurrent state), the normal state and the short circuit accident can be distinguished from the state of the current.

Therefore, based on the detection result of the power state and the output of the network relay, it is determined whether or not the protector breaker is in a state to be opened, and opening control is performed as necessary. As a result, unnecessary opening of the protector breaker can be prevented, power can be supplied stably, and supply reliability can be increased. It should be noted that the criterion for determining whether or not to open is not limited to the above.

The power state to be detected can be of various types. For example, the power state is the magnitude of the power and the phase of the current with respect to the voltage. The magnitude of the power is smaller than the set value, and the phase of the current is advanced. ", The protector circuit breaker may be opened (claim 2). That is, for example, when the network line is under a light load and under certain conditions, the power may be extremely small even in a normal state. However, since power is supplied to the load, the phase of the current is “lagged”. On the other hand, in the case of rolling blackouts,
The phase of the current is “advanced”. Therefore, if it is determined whether or not to open based on the magnitude and phase of the power, the opening command can be output more reliably without malfunction.

The network relay may open the protector breaker when the network line is in a reverse power state and in an overcurrent state (claim 3).
As a result, the network relay outputs an open command in the event of a short circuit, and does not output an open command in the event of a planned power outage or a ground fault. The rolling blackout and the like are described in claim 2
Is executed, the release instruction is output.

In the present invention, the network relay does not output an opening command only at the time of reverse power and at the time of overcurrent as in claim 3, but as conventionally used,
The opening command may be output even when the power is not an overcurrent due to the reverse power. That is, the network relay may also output a release command at the time of a planned power outage or the like, which has conventionally been released (protection processing). And "Reverse power +
Even when there is no overcurrent, it is possible to control so that the protector breaker is not opened when the power state on the power supply side from the branch point of the distribution line is constant.

As a protection system suitable for carrying out the above method, for example, the network relay detects a reverse power of the network line, and detects an overcurrent of the network line. It has an overcurrent detection function and outputs an open command to the protector breaker when both detection functions output, and the power detection means is a branch point from the distribution line to the network line. A current transformer inserted in the vicinity and on a power distribution line, a power relay connected to an output side of the current transformer, and detecting power at a current transformer installation position; and A current phase relay that detects a current phase at a position, wherein the power relay detects that a magnitude of power is smaller than a set value, and the current phase relay has It may also be output opening instruction to the protector breaker when it is detected that the phase is "proceeds" (claim 6).

[0024] Further, a service standby power receiving line is further connected to the predetermined distribution line, and a power state on the power distribution line near the branch point to the service standby power receiving line on the power distribution line is detected. The switching control of the main circuit breaker in the regular standby power receiving line may be performed based on the detection result of the power state (claim 4).

As a protection system suitable for carrying out the above-mentioned method, for example, a regular standby power receiving line is further connected to the predetermined distribution line, and a branch from the distribution line to the normal standby power receiving line is provided. It is possible to further comprise a power detecting means for detecting a power state on the power distribution line near the point and to control the opening and closing of the main circuit breaker based on a detection result of the power detecting means ( Claim 7). By doing so, the main circuit breaker can be opened in the event of a ground fault or the like.

[0026]

FIG. 1 shows a first embodiment of the present invention. As shown in the figure, the basic configuration is the same as the conventional one. In the present embodiment, network lines 4a and 4b are connected to two transmission lines 1a and 1b, respectively, and the network lines 4a and 4b are connected via the network lines 4a and 4b. It is connected to the network bus 5. Further, a regular standby power receiving line 19 is connected to the distribution line 1a. Then, each line 4a, 4
Since the internal structures of b and 19 are basically the same as the conventional one shown in FIG. 7, the same reference numerals are given and the explanation of each part is omitted.

Here, in the present invention, the distribution lines 1a, 1b,
The commercial power supply 3a at the branch point of the network lines 4a, 4b,
Current transformers 20a and 20b are mounted on the 3b side. The current transformers 20a and 20b are close to the branch point. The outputs (secondary circuits) of the current transformers 20a and 20b are connected to the power relays 21a and 21b and the current phase relay 22.
a, 22b. Further, conventionally, the instrument transformer 10 in the network lines 4a and 4b is used.
Outputs of the network relays 11a and 11b
In this example, the power relays 21a and 21b and the current phase relays 22a and 22b are provided together with the network relays 11a and 11b.
b.

The power relays 21a and 21b are provided with current transformers 20a and 20b based on current information obtained from the current transformers 20a and 20b and voltage information obtained from the instrumentation transformers 10a and 10b. The detected power is detected at a position where it is, and a detection signal is output when the detected power is equal to or greater than a set value. In addition, the current phase relay 22
a and 22b are phases of the current with respect to the voltage at the position where the current transformers 20a and 20b are installed, based on the current information obtained from the current transformers 20a and 20b and the voltage information obtained from the instrumentation transformers 10a and 10b. And outputs a detection signal when the phase is “advanced”. When the detection signal is not output from the power relays 21a and 21b (the power is small) and the detection signal is output from the current phase relays 22a and 22b (the phase is "advanced"), the corresponding protector breaker 8a, 8b is opened.

Further, as in the conventional case, the network relay 1
The protector circuit breakers 8a and 8b are also controlled to open and close based on the detection signals from 1a and 11b. However, conventionally, when only the reverse power detection function in the network relays 11a and 11b detects, a release command is output after a lapse of a set time to open the circuit breaker, and the reverse power detection function and the overcurrent detection function are performed. If they are detected simultaneously, an open command is output instantaneously to open the circuit breaker.However, in the present invention, the open command is output only when the reverse power detection function and the overcurrent detection function are simultaneously detected, When only the reverse power detection function detects, the network relays 11a and 11b do not output the release command. As a result, in the event of a planned power outage or a ground fault, although a reverse power flow occurs and reverse power is generated, the open command is not output because the current value is small. That is, the network relays 11a and 11b according to the present embodiment output an open command only when a short circuit accident occurs. The protector circuit breakers 8a and 8b are connected to the "network relays 11a and 1
1b "and" power relays 21a, 21b + current phase relays 22a, 22b "when a release command is output.

Similarly, a current transformer 24 is mounted on the distribution line 1a and also on the commercial power supply 3a side of the branch point of the regular standby power receiving line 19. A power relay 25 and a current phase relay 26 are provided in the secondary circuit of the current transformer 24, and the opening and closing of the main circuit breaker 16 is controlled based on the detection outputs of the two relays 25 and 26. ing. The current transformer 2 is also provided on the commercial power supply 3b side of the branch point (connection point with the main circuit breaker 16 ') in the distribution line 1b as a backup line.
Attach 4 '. The secondary circuit of the current transformer 24 'has a power relay 25' and a current phase relay 26 '
And the opening and closing of the main circuit breaker 16 'is controlled based on the detection outputs of both relays 25' and 26 '.

The power relays 25, 25 '
The power at the position where the current transformers 24 and 24 'are installed is detected, and a detection signal is output when the detected power is equal to or more than a set value. In addition, the current phase relay 26,
26 'detects the phase of the current with respect to the voltage at the position where the current transformers 24 and 24' are installed, and outputs a detection signal when the phase is "leading". When the detection signals are not output from the power relays 25 and 25 'and the detection signals are output from the current phase relays 26 and 26', the corresponding main circuit breakers 16 and 16 'are opened.

Next, an embodiment of the protection method according to the present invention will be described using the above-described device.

* In the case where the network line is lightly loaded In the case of the present embodiment in which the regular standby power receiving line 19 is connected to the distribution line 1a, if the network lines 4a and 4b are lightly loaded, the network line is connected to the distribution line 1a. A potential difference occurs between the branch point to the network line 4b and the branch point to the network line 4b. Then, as shown by an arrow A in FIG. 2, a reverse flow flows from the network line 4b toward the network line 4a based on the potential difference.

Then, since reverse power is generated in the network line 4a, the reverse power detecting function of the network relay 11a detects the reverse power flow. However, since the current value of the reverse power flow is small, the overcurrent detection function is not detected. Therefore, no release command is output from the network relay 11a.

Further, the reverse power flow flows into the distribution line 1a from the branch point and flows into the regular standby power receiving line 19 side. At this time, the reverse power flow flows from the commercial power supply 3a upstream of the branch point to the distribution line 1a in the direction of arrow B. And power is sent to a load used by each line connected to the distribution line 1a. Therefore, predetermined electric power exists at the position of the current transformer 20a, and the electric power relay 21a detects the electric power and outputs a detection signal. Therefore, regardless of the output of the current phase relay 22a, no opening command is output from the power relay 21a and the current phase relay 22b to the protector breaker 8a.

Therefore, in the normal state where power is supplied from the commercial power supply 3a, the protector circuit breaker 8a is not erroneously opened even if a reverse power flow due to a light load occurs. Network line 4
Power can be supplied to the a side. Of course, regular standby power receiving line 1
Since electric power is also generated at the position of the current transformer 24 on the ninth side,
Since the power relay 25 detects this, no open command is output to the main circuit breaker 16 of the regular standby power receiving line 19.

When the amount of electric power generated by the private generator is large When the private generator 15 is connected to the network bus 5, the power generation capacity of the private generator 15 is equal to the network line 4 a, If the load capacity exceeds the load capacity being used in 4b, the excess is diverted as reverse power flow as shown by arrows D and E in FIG. Thus, the reverse power detection function of the network relays 11a and 11b detects the reverse power flow, but does not detect the overcurrent detection function because the current value of the reverse power flow is small. Therefore, no release command is output from the network relays 11a and 11b.

Then, from the commercial power supply 3a, 3b, the distribution line 1
Power is supplied in the directions of arrows F and G on the lines a and 1b, and the lines connected to the distribution lines 1a and 1b transmit the power to the loads used by the current transformers 20a and 20b.
A predetermined power is present at the position
a and 21b detect it and output a detection signal. Therefore, regardless of the output of the current phase relays 22a, 22b, each of the relays 21a, 21a connected to the distribution lines 1a, 1b.
No opening command is output from the corresponding protector breakers 8a, 8b from the respective 21b, 22a, 22b. Therefore, in the normal state where power is supplied from the commercial power sources 3a and 3b, the protector circuit breakers 8a and 8b are not accidentally opened even if the amount of power generated by the private generator 15 is large.

* In the case of a planned power outage In this example, as described above, the release command is output only when the release command from the network relay detects both the reverse power detection function and the overcurrent detection function. As a result, rolling blackouts and ground faults that could be detected with the conventional configuration cannot be detected. However, in the present embodiment, the power relays 21a, 21b and the current phase relays 22a, 22b
By providing the above, such a situation is also detected, and the protector breakers 8a and 8b can be opened.

That is, when the power distribution line 1a is to be subjected to planned power outage, the main circuit breaker 16 of the regular standby power receiving line 19 is opened prior to operation. Along with this, the main backup circuit breaker 16 'is connected to the service standby power receiving line 19 and connected to the distribution line 1b. Thus, the distribution line 1a is provided with the spot network power receiving equipment, that is, the network lines 4a,
4b is connected, and thereafter, the distribution line breaker 3a connected to the distribution line 1a is opened, and power supply from the commercial power supply 3a is stopped. Then, since there is no load connected to the distribution line 1a, the power becomes zero. Therefore, the distribution line 1a
The power relay 21a connected to is not detected and output because the set value is a predetermined value larger than zero.

On the other hand, since power is supplied to the distribution line 1b from the commercial power supply 3b, as shown by an arrow H in FIG.
Electric power flows from the distribution line 1b to the distribution line 1a via the network line 4b, the network bus 5, and the network line 4a. However, the load is not connected, and the current flowing through the distribution line 1a is only the charging current between the distribution line 1a and the ground, and the phase of this current is "leading".
Therefore, a detection output is output from the current phase relay 22a. Therefore, since the current phase relay 22a does not output the power relay 21a but outputs the current, the protector circuit breaker 8a is opened and disconnected from the distribution line 1a. Along with that,
The power of the path indicated by the arrow H in the figure disappears. Although the figure shows an example in which one network line 4a and the regular standby power receiving line 19 are connected to the distribution line 1a for convenience, a plurality of lines are actually connected. However, similarly to the above-described principle, the power relay connected to the distribution line 1a has no output, and the current phase relay connected to the distribution line 1a has a phase of "only" because only the charging current flows on the distribution line 1a. Proceed ”
Is output. Therefore, the protector breakers in all the network lines connected to the distribution line 1a are opened.

* In the case of a ground fault In the event of a ground fault, unlike the case of a planned power outage, the regular standby power receiving line 19 is connected to the distribution line 1a. When a ground fault occurs on the distribution line 1a, the distribution line breaker 2a is opened. As a result, power supply from the commercial power supply 3a is stopped, so that the arrow I in FIG.
As shown in FIG.
b, power flows to the distribution line 1a via the network bus 5 and the network line 4a. Although FIG. 2 shows a state in which a plurality of (two) network lines are connected, similarly, as shown by an arrow J in FIG.
The distribution line 1a also passes through the network line 4'b, the network bus 5 ', and the network line 4'a from the side.
Power flows through

At this time, at the position where the current transformer 20a on the side of the commercial power supply 3a (upstream) is installed, there is no connected load, so that the power becomes zero, so that there is no output from the power relay 21a. In addition, since the currents I and J from the distribution line 1b flow from the branch point toward the service standby power receiving line 19 (downstream side), the distribution line 1a extends from the distribution line breaker 2a to the current transformer 20a. There is only the charging current between the grounds, and the phase is “advanced”. Therefore, a detection output is made from the current phase relay 22a. Therefore, the protector breaker 8a is opened. Along with this, the power supply path indicated by the symbol I disappears.

In the state before the protector breaker 8a is opened, the reverse power generated in the network line 4a flows toward the load of the regular standby power receiving line 19 at the installation position of the current transformer 20'a. . That is, since power is supplied from the distribution line 1b to the service standby power receiving line 19 via the route I, power is generated at the position of the current transformer 20'a, and the power relay 21'a detects the power. , A detection output is made. Therefore, the protector breaker 8'a in the network line 4'a is not opened.

On the other hand, when the protector circuit breaker 8a of the network line 4a is opened according to the above principle, the power supply via the network line 4a stops, so that the power in the current transformer 20'a disappears and the power relay 21 ' a
No more output. Considering the current at the set position of the current transformer 20'a at this time, the charging current between the distribution line 1a and the ground and the transformer 7a in the network line 4a on the power supply 3a side from the current transformer 20'a are considered. Of the excitation current. As described above, the phase of the charging current is “leading”, but the phase of the exciting current is lagging. However, since the charging current is much larger than the exciting current, the phase of the combined current becomes “advanced” according to the phase of the charging current. as a result,
An open command is output to protector breaker 8'a. As a result, the power supply path indicated by the symbol J disappears.

By repeating the above principle,
All the network lines connected to the commercial power supply 3a side from the regular standby power receiving line 19 operate so as to open the built-in protector breaker in order from the power supply side and disconnect from the distribution line 1a. In the case of the second or subsequent network line from the power supply side, when the network line upstream of the network line is opened, the current transformer is installed in the network transformer held by the open network line. The total value of the no-load loss of the vessel will be added. Therefore, in practice, the set value that is the reference for the power relay to output is
The value should be set to be larger than the total value of the no-load loss of the network transformer.

When the network line upstream of the regular standby power receiving line 19 is disconnected, the following operation is performed. That is, the power supply from the distribution line 1b is stopped, and the load at the installation position of the current transformer 24 is the sum of the no-load loss of the network transformer held by the open network circuit on the power supply side. By setting the set value of the power relay 25 to be equal to or more than the total value,
No output. The phase of the current in the current transformer 24 is the same as the phase of the charging current between the distribution line 1a and the ground, as in the case of the current phase relay 22'a associated with the second network line 4'a. As a result, the current phase relay 26 outputs a detection output. Based on this, the main circuit breaker 16 in the regular standby power receiving line 19 is opened.

Even when a plurality of regular standby power receiving lines are connected, the main circuit breaker is opened in order from the power supply side and disconnected from the distribution line 1a by sequentially repeating the above-described principle.

In the case where a network line is further connected to the downstream side of the regular standby power receiving line (the side far from the commercial power supply: outside the right side in FIG. 5),
Since the load on the distribution line 1a is eliminated by disconnecting the regular standby power receiving line farthest from the power source, the protector breakers of all network lines are opened according to the same principle as that of the above-mentioned rolling blackout.

* In the case of a short-circuit accident When a short-circuit accident occurs, reverse power is generated in each network line and an excessive current flows. Therefore, according to the same principle as in the conventional method, each network line has The state (reverse power + overcurrent) of the network relay is detected, and the protector breaker is opened.

* Others As shown in FIG. 6, when the load of the spot network power receiving equipment (network line 4 ″ a) at the end of the distribution line 1a is light and immediately before and after the reverse power flow occurs, Since there is no load on the downstream side, the electric power at the installation position of the current transformer 20 "a is supplied to the lightly-loaded network line 4" a side, and is very small and close to zero. Then, the output of the power relay 21 ″ a connected thereto disappears. However, since power is supplied to the load,
The phase does not become “advanced” and the current phase relay 22 ″ a is not output.
An open command is not output to the protector breaker, and power can be reliably supplied even with a light load.

[0052]

As described above, in the method and system for protecting the spot network power receiving equipment according to the present invention, the detection result of the network relay and the state of the power on the power supply side with respect to the branch point to the network line of the distribution line. In order to control whether or not to finally open the protector breaker based on the above, even if reverse power is generated in the network line, the power state that appears at the branch point is different between the normal state and the abnormal state, By taking such a power state into consideration, unnecessary opening of the protector breaker can be prevented, and power can be stably supplied. Therefore, supply reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment of the present invention.

FIG. 2 is a diagram showing a reverse power flow that occurs when the spot network power receiving equipment has a light load in a state where a regular standby power receiving line is connected to the distribution line shown in FIG. 1;

FIG. 3 is a diagram showing a reverse power flow generated by a link between a commercial power supply and a private generator in the state shown in FIG. 1;

FIG. 4 is a diagram illustrating an operation principle in the case of a planned power outage.

FIG. 5 is a diagram illustrating an operation principle in the case of a ground fault.

FIG. 6 is a diagram for explaining the operation principle when the spot network power receiving equipment connected to the end of the distribution line has a light load.

FIG. 7 is a diagram showing a conventional example.

[Explanation of symbols]

 1a, 1b Distribution line 2a, 2b Distribution circuit breaker 3a, 3b Commercial power supply 4a, 4b Network line 8a, 8b Protector circuit breaker 11a, 11b Network relay 15 Private generator 16 Main circuit breaker (for regular standby power receiving line) 19 Regular standby Power receiving line 20a, 20b Current transformer 21a, 21b Power relay 22a, 22b Current phase relay 24 Current transformer (for regular standby power receiving line) 25 Power relay (for regular standby power receiving line) 26 Current phase relay (for regular standby power receiving line) )

Claims (7)

[Claims] 1. A network power receiving facility for connecting a plurality of distribution lines and a network bus by a network line having a primary switch, a network transformer, and a protector breaker for each distribution line, and mounted on the network line. A protection method that opens the protector breaker based on a control signal from a network relay, wherein the power supply side is near a branch point from the distribution line to the network line, and on a power supply side. A method for protecting a spot network power receiving equipment, comprising detecting a power state, and controlling opening and closing of the protector circuit breaker based on a result of the detection of the power state and an output of the network relay. 2. The power state to be detected is a magnitude of power and a phase of a current with respect to a voltage. When the magnitude of the power is smaller than a set value and the phase of the current is “advanced”, the protector circuit breaker is activated. 2. The method for protecting a spot network power receiving equipment according to claim 1, wherein the communication network is opened. 3. The spot network power receiving equipment according to claim 2, wherein the network relay opens the protector breaker when a network line is in a reverse power state and in an overcurrent state. Protection method. 4. A predetermined standby power receiving line is further connected to the predetermined distribution line, and a power state on the power distribution line near the branch point to the standby standby power receiving line on the distribution line is detected. The protection of the spot network power receiving equipment according to any one of claims 1 to 3, wherein switching control of a main circuit breaker in the regular standby power receiving line is performed based on a detection result of the power state. Method. 5. A network receiving device for connecting a plurality of distribution lines and a network bus by a network line having a primary switch, a network transformer, and a protector breaker for each distribution line, and mounted on the network line. A protection system that opens the protector breaker based on a control signal from a network relay, wherein the power is near a branch point from the distribution line to the network line and on a power supply side distribution line. Protection of a spot network power receiving facility, further comprising power detection means for detecting a state, wherein opening and closing of the protector breaker is controlled based on a detection result of the power detection means and an output of the network relay. system. 6. The network relay has a reverse power detection function for detecting a reverse power of the network line and an overcurrent detection function for detecting an overcurrent of the network line. The power detection means outputs an open command to the protector circuit breaker, and the power detecting means is located near a branch point from the distribution line to the network line and is inserted in a power line inserted on the power supply side distribution line. And connected to the output of the current transformer,
A power relay that detects power at a current transformer installation position,
A current phase relay for detecting a current phase at the current transformer installation position, wherein the power relay detects that the magnitude of the power is smaller than a set value, and the current phase relay is “leading” in phase. The protection system for a spot network power receiving equipment according to claim 5, wherein when detecting the fact, an open command is output to the protector breaker. 7. A predetermined standby power receiving line is further connected to the predetermined distribution line, and a power state on a power distribution line near a branch point from the distribution line to the normal standby power receiving line is detected. 7. The protection system for spot network power receiving equipment according to claim 5, further comprising: a power detection unit that performs opening / closing control of the main circuit breaker based on a detection result of the power detection unit.