JPS6347052B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protector and disconnector tripping device, and more particularly, to a protector and disconnector in a network power distribution device that prevents reverse power from being interrupted due to the power generation action of the load and also prevents the tripping of the load from the load. Even during reverse power generation, 1
Relating to a network protector equipped with a fault line detection circuit that detects the occurrence of reverse power from the network busbar due to a ground fault in the feeder line and trips the protector and disconnector. .

What is important when supplying power to a power distribution system is to supply power with stable voltage and frequency without power outages. One of the countermeasures against this problem is a network power distribution device. This network power distribution equipment connects the primary distribution feeder line to two
In addition to the above, each feeder line is connected in parallel with a network bus or cable via a power receiving disconnector, network transformer, and protection device.This protection device is called a network protector and There is no response to an accident within the work, that is, on the load side, and in the case of an accident on the primary feeder line, there is no response from other healthy feeder lines to the faulty feeder line via the network circuit. Ability to quickly remove power (so-called reverse power cutoff)
have. Network power distribution devices include regular network power distribution devices and spot network power distribution devices.

Although the present invention is applicable to network power distribution devices in general, for convenience of explanation, a spot network power distribution device applied to, for example, power distribution within a building will be described as an example.

FIG. 1 shows a schematic wiring diagram of a spot network power distribution system having three primary feeder lines. In the figure, the power substation SS mustard disconnector
CB ₁ ……… Primary feeder line PL ₁ ……… via CB ₃
Power receiving disconnector DS ₁ ......DS ₃ Network protector NW・Pro ₁ ......NW・Pro ₃ for each PL ₃
is connected, and the secondary side NW of this protector is
Pro ₁ ......NW・Pro ₃ is the network bus NW・
Connected in parallel at B, take-off device TO ₁ ...... TO ₄
It is connected to each load (not shown) via. The reverse power cutoff function of the network protector has been described above, and the details of this function and other functions are as follows.

(1) In the case of a short circuit accident in the primary feeder line.

After the breaker at the substation is tripped, a fault current from the network circuit is detected and the breaker is tripped.

(2) In the case of a ground fault in the primary feeder line.

After the substation switch or disconnector is tripped, the vector sum of the transformer excitation current and wire charging current from the network circuit is detected and the protector switch or disconnector is tripped.

(3) When the primary feeder line is charged and the network circuit is without voltage.

The protector and disconnector are switched on without voltage.

(4) When the network circuit side is charged and any protectors or disconnectors are tripped.

In this case, the difference between the voltage on the primary feeder side and the voltage on the network circuit side and the phase difference between the two voltages are detected, and when the conditions are met, the protector and disconnector are turned on again. (Differential Voltage Application) Figure 2a shows an overview of the network protector in a single connection diagram. In the figure, it is connected to the secondary side of the network transformer NW/Tr,
It consists of a protector fuse Pro-F, a protector fuse Pro-CB, and a relay device NW-Ry. The relay device NW/Ry is composed of a power direction relay 67, a phase relay 78, a current transformer for obtaining operation input from these, and an auxiliary transformer PT as required. FIG. 2b shows a control circuit for tripping or closing the protector and disconnectors Pro and CB by the output of the relay device NW and Ry.

In FIGS. 2a and 2b, the power direction relay 6
7 determines the direction of the power flowing in the main circuit, and connects the contact output of reverse power interruption or re-input (no voltage, differential voltage) to the tripping coil TC or closing coil CC of the protector or disconnector Pro/CB. I am learning to give. The phase relay 78 functions only when the power direction relay 67 is turned on again, and determines the phase relationship between the no-load voltage on the secondary side of the transformer and the voltage on the network bus side. Closing coil CC connected in series with contact output 67C
It is becoming more and more common to give money to people. Therefore, the re-closing contact output 67C of the power direction relay 67 is the closing coil.
Even if CC is applied, the closing coil CC will not be energized unless the contact output of the phase relay 78 is applied.
The protector and disconnector Pro/CB will not be reinserted.

Now, when considering the reverse power failure of the network protector, the conditions for the failure to occur are a large current of reverse power such as a short circuit accident in the primary feeder, and a no-voltage condition in the primary feeder. There are cases of reverse power of minute currents such as the vector sum of the charging current of the primary wire and the excitation current of the transformer, which requires extremely high sensitivity.

Furthermore, if the network load includes a load that performs regenerative braking, such as an elevator, and the other loads in this system are light, the regenerative power may cause the network bus voltage to rise, albeit for a short time, from the primary feeder line. It may be higher than the voltage. This causes a phenomenon in which power is sent backwards from the network bus side to the primary feeder, and even though the primary feeder is normal, the power direction relay is highly sensitive and transmits reverse power. It will be detected and a trip command will be given to the protector or disconnector.

However, since the reverse power generated by regenerative braking disappears in a short period of time, the relay device immediately issues a closing command to the protector or disconnector to perform unnecessary disconnection and reconnection operations. Moreover, in this case, all the network protectors supplying power will be operating, so there will be no voltage on the network bus side, which is not compatible with the purpose of network power distribution equipment, which is to provide uninterrupted power supply. Become something.

Therefore, in order to avoid such unnecessary operations, in the past, as shown in, for example, Japanese Utility Model Publication No. 51-49561 and Japanese Patent Publication No. 52-33294, when the reverse power exceeds a certain value, the protector is instantly activated. If the reverse power is less than a certain value, the power direction relays of all lines are tripped to the protector or disconnector, taking advantage of the fact that reverse power is generated in all lines due to regenerative braking when the reverse power is less than a certain value. When a disconnection command is given, all protectors and disconnectors are not tripped.

However, let us now consider a case where a ground fault occurs in the primary feeder line while reverse power is being generated due to regenerative braking. In this case, the protective device at the outlet of the primary feeder line at the substation will trip the power supply side disconnector in a few seconds, stopping the power supply to the point of the ground fault. Furthermore, a current equal to the vector sum of the transformer excitation current and the wire charging current flows through the line where the ground fault occurred.
Reverse power is generated by regenerated power. In the conventional method, as mentioned above, when reverse power is generated in all lines, the protector and disconnector are not tripped, so in this case, the line where the fault occurred is not disconnected and the fault current continues to flow. As a result, the original function of the network protector will be impaired.

The present invention has been made in order to eliminate the above-mentioned drawbacks, and its purpose is to ensure that even if a ground fault occurs during regenerative power generation, the fault current flowing backward from the network bus can be quickly cut off. Our goal is to provide a network protector that can

First, an overview of the present invention will be described. If only regenerative power is used for an elevator or the like, a reverse current due to the regenerative power is divided into each line, so the current flows with exactly the same amplitude and phase. On the other hand, when a ground fault occurs, the current that is the vector sum of the transformer excitation current flowing to the fault line and the feeding line charging current due to the ground fault, and the current flowing to the healthy line due to regenerated power have different amplitudes. , the current will be different in phase. However, since the reverse current due to the regenerated power is shunted to other healthy lines, the same current flows in both amplitude and phase.
In the present invention, this fact is used to distinguish between the two,
Even if a ground fault occurs during regenerative power generation, the system attempts to quickly cut off the fault current flowing backward from the network bus bar.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 shows an example of the configuration of a network protector in a spot network power distribution system according to the present invention, and the same parts as in FIGS. 1 and 2 are given the same reference numerals and their explanation will be omitted. Note that Figure 3 shows a case where one network group is composed of three lines, #1, #2, and #3.
are the first, second and third lines, respectively. In the figure, reference numeral 1 denotes a faulty line detection circuit, which is composed of, for example, a digital circuit. Reference numerals 2a, 2b, and 2c are current transformers provided in each line, and 3a, 3b, and 3c are signal lines for receiving protector and disconnection tripping commands for each line into the faulty line detection circuit 1.

FIG. 4 shows a flowchart for explaining the operation of the faulty line detection circuit 1. As shown in FIG. Figure 5 shows the tripping circuit for the protector and disconnector.
4 is an a contact of the power direction relay 67 of the network relay, and 5 is a b contact energized by the output of the failure line detection circuit 1.

In this configuration, the load EL shown in Figure 3 now generates regenerative power, so the network bus
The voltage of NW・B is the primary feeder wire PL ₁ , PL ₂ and PL ₃
If the voltage becomes higher than that of the network protector NW・Pro ₁ , NW・Pro ₂ and NW・
Power is sent back to the primary power line via Pro ₃ .
Therefore, the network protector for each circuit is
The reverse power cutoff function issues a command to trip the protector and disconnector. In STEP 8, 5a, 5b, and 5c refer to the contacts 5a, 5b, and 5c in FIG. 5, and the contacts 5b and 5c are opened, but the contact 5a is closed. Here, contacts 4a, 4b, and 4c are all already closed because reverse power is generated in all lines, so the protector and disconnector Pro.
Only CB ₁ is tripped and the fault line #1 is disconnected.

In addition, if a ground fault occurs on line #2,
In Figure 4, STEP1→STEP2→STEP3→
Proceed to STEP 4. In this case, #2 is the accident line.
The amplitude value of the current flowing through the line is different from the amplitude value of the current due to the regenerative power flowing through the #3 line, so
Proceed from STEP 4 → STEP 6. On the other hand, #1 line and #3
Since both lines have the same amplitude of current due to regenerated power, the process proceeds from STEP 6 to STEP 9. 5 in STEP9
a, 5b, 5c are contacts 5a, 5 in Fig. 5.
b, 5c, contacts 5a, 5b, 5c are open, but contact 5b is closed. Then,
As in the case where a ground fault occurs on the #1 line, only the protector and disconnector Pro/CB ₂ is tripped.

Furthermore, if a ground fault occurs in line #3, only the protector and disconnector Pro/CB ₃ will be tripped.

In this way, the multi-line network protector NW Pro connects the primary feeder line and the secondary power distribution system.
A power direction relay 67 that determines the power direction and responds is installed in the circuit, and when any power direction relay in the line in operation operates, a protector or disconnector Pro/CB corresponding to that power direction relay is installed. is set to trip immediately, and on the condition that all power directional relays 67 of the lines in operation are activated, calculate and compare the amplitude values of the currents flowing in each of the lines, and If the current amplitude values are equal, all protectors and disconnectors are prevented from tripping, and if the current amplitude value of a certain line is different from the amplitude value of other lines, the protector of that line is blocked. A network protector equipped with a fault line detection circuit is equipped with a fault line detection circuit that has the function of tripping only the disconnector and protecting other lines and preventing the disconnector from tripping. be.

Therefore, even if a load that generates power, such as an elevator, is installed, it is possible to not only prevent a total power outage across one network group, but also prevent the primary power line from being damaged during regenerative power generation. A ground fault can be immediately detected and disconnected from the network system, and the original function of a network protector can be fully fulfilled.

By the way, in the above embodiment, the fault line detection is
This is done by comparing the amplitude values of the currents flowing through each line, but when the regenerated power is extremely small, the current shunted to the healthy line will be very small, and it may be difficult to distinguish it from the fault current. be. However, the current that is the vector sum of the transformer excitation current and the feeder charging current that flows through the faulty line has a phase that is significantly different from the current that is shunted to the healthy line by regenerative power. By using a method of comparing both the current value and the phase of each line for line detection, faulty lines can be detected even more accurately.

Examples in this case will be described below with reference to FIGS. 3, 5, and 6. Figure 6 shows
4 is a flowchart showing the operation of the faulty line detection circuit 1 of FIG. 3 when detecting a faulty line by comparing the amplitude value and phase of the current. FIG.

Now, if regenerative power is generated from the load EL in Figure 3 and power is sent back to each line, the network protectors NW・Pro ₁ , NW・Pro ₂ and
NW・Pro ₃ has a reverse power cutoff function, which makes it possible to use protector cutoffs Pro・CB ₁ , Pro・CB ₂ , and Pro・CB _3.
Issue a tripping command to.

The operation of the failed line detection circuit 1 in this case will be explained using FIG. 6. First, in STEP 1, a command to trip the protector and disconnector of each line is received.
Next, in STEP 2, a command to trip the protector and disconnector is issued from the protector from all lines.
Proceed to STEP3. In STEP 3, the current of each line is taken from the current transformer 2 shown in FIG. 3, and the amplitude value of the current is determined.
In addition, in STEP 4, the phase difference of the current between each line is calculated from the current of each line taken from the current transformer.
Proceed to STEP4 → STEP5. And STEP 5~
In STEP 10, a determination is made by comparing the amplitude values of the currents of each line and checking whether the phases of the lines are equal. In this case, since only regenerative power is used, the amplitude value of the current in each line is the same, and the phase of each line is also the same, so the phase difference between each line is zero. So, STEP5→STEP6→STEP7→STEP8→
Proceed to STEP11. The 5a, 5b, and 5c in STEP 11 refer to contacts 5a, 5b, and 5c in Figure 5, and since all contacts 5a, 5b, and 5c are opened in STEP 11, all protectors and disconnectors are not tripped. .

However, if a ground fault _F1 occurs in the primary feeder line _PL1 in Figure 3 while regenerative power is being generated, the transformer excitation current and wire charging current will flow from the network bus NW/B to the fault line. A vector sum current flows. In this case, the current flowing through the #1 line will be different from the current that is shunted to the #2 and #3 lines due to regenerative power, at least in either the current amplitude value or the phase, so the flow diagram shown in Figure 4 Well then
STEP1→STEP2→STEP3→STEP4→STEP5→
Proceed to STEP 6 → STEP 7, and if the amplitude value of the current of #1 line is different from the amplitude value of the current of other lines, STEP 7 →
Proceed to STEP12. Faulty line detection circuit 1 in this case
The operation will be explained with reference to FIG. First, STEP1
Then, a command to trip the protector or disconnector of each line is received from the signal line 3 in FIG. Next, in STEP 2, check whether a command to trip the protector or disconnector has been issued from all lines. In this case, all network protectors have issued instructions to trip the protectors and disconnectors, so proceed to STEP 3. STEP3
Now, the current of each line is taken from the current transformer 2 in Fig. 3, the amplitude value of the current is determined, and the process proceeds from STEP 3 to STEP 4.
Next, in STEP4 to STEP6, the current amplitude values of each line are compared and a determination is made. In this case, since there is only regenerated power, the amplitude value of the current in each line is the same, so the process proceeds in the order of STEP4→STEP5→STEP7. In STEP 7, 5a, 5b, 5c are the 5th
These are the contacts 5a, 5b, and 5c in the figure.
STEP 7 Since all contacts 5a, 5b, and 5c are opened, all protectors and disconnectors are not tripped.

However, if a ground fault _F1 occurs in the primary conductor _PL1 in Figure 3 while regenerative power is being generated, the vector sum of the transformer excitation current and the wire charging current will be Current flows backwards, #1
Issues a command to the network protector NW Pro ₁ of the line to trip the protector and disconnector using the reverse power disconnection function. However, #1 line has #2 and #3
Since a fault current that is different from the circuit current flows, the flow diagram in Figure 4 shows STEP1→STEP2→STEP3→
The process proceeds from STEP4 to STEP5, and in STEP5, the current amplitude values of the #1 line and #2 line are different, so the process proceeds to STEP8. In the unlikely event that the current amplitude values of the #1 line and other lines are the same, the process proceeds from STEP7 to STEP8, but since there is a phase difference between the currents of the #1 line and other healthy lines, STEP8 → Proceed to STEP12.
5a, 5b, and 5c in STEP12 refer to the contacts 5a, 5b, and 5c in FIG. 5, and in STEP12, the contacts 5b and 5c are opened, but the contact 5a is closed. Furthermore, contact 4 is already closed because reverse power is generated in all lines, so
Only the protector and disconnector Pro/CB ₁ is tripped, and the fault line, #1 line, is disconnected.

On the other hand, if a ground fault occurs in the #2 and #3 lines, it will be determined in the same way in STEP 5 to STEP 10, and the process will proceed to STEP 13 and STEP 14. , 5c are opened and closed.

In addition, the present invention can be modified and implemented in various ways without changing the gist thereof.

As explained above, according to the present invention, even if a ground fault occurs during regenerative power generation, an extremely reliable network can be created that can quickly and reliably cut off the fault current flowing backward from the network bus. Protectors can be provided.

[Brief explanation of the drawing]

Fig. 1 is a schematic wiring diagram showing a spot network power distribution equipment, Figs. FIG. 5 is a block diagram showing an embodiment of the present invention in a three-line spot network power distribution device, a flow chart explaining the operation of the faulty line detection circuit in FIG. 6 is a flowchart explaining the operation of the failure circuit of FIG. 3 in another embodiment of the present invention and a circuit diagram for tripping the protector and disconnector; FIG. FIG. 4 is a flowchart illustrating the operation of the faulty line detection circuit of FIG. 3; NW・Pro……Network protector,
Pro・CB……Protector and disconnector, NW・B……
Network busbar, TC...Protector and breaker tripping coil, 67...Power direction relay, 1...
Failure line detection circuit, 2... current transformer, 3... signal line.

Claims (1)

[Scope of Claims] 1. A power direction relay that determines the power direction and responds by determining the power direction is provided in a network protector for multiple lines connecting the primary feeder line and the secondary power distribution system, and When any power directional relay operates, the protector or disconnector corresponding to the power directional relay is tripped,
The amplitude values of the currents flowing through each line are calculated and compared on the condition that all the power direction relays of the lines in the operating state have operated, and if the amplitude values of the currents of all lines are equal, all protector or disconnector from tripping, and if the current amplitude value of one line is different from the current amplitude value of another line,
A network protector comprising a faulty line detection circuit having a function of tripping only the protector or disconnector of the line and preventing the protectors or disconnectors of other lines from being tripped. 2 A power direction relay that determines the power direction and responds by determining the power direction is installed in the network protector for multiple lines that connect the primary feeder line to the secondary distribution system, and any power direction relay among the lines that are in operation is activated. When the line is in operation, the protector or disconnector corresponding to the power directional relay is tripped when the power directional relay is in operation. The amplitude value and phase of the current flowing through each line are calculated and compared on the condition that all the directional relays of In addition, if the amplitude value or phase of the current in a certain line is different from the current amplitude value or phase in another line, tripping only the protector or disconnector of that line, A network protector comprising a faulty line detection circuit having a function of protecting other lines and preventing tripping of a disconnector.