JPH0458136B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuse rupture detection device, particularly for detecting the rupture of a fuse connected to the secondary side of a voltage transformer of a power transmission line drawn out from a bus system. The present invention relates to a blown fuse detection device.

[Conventional technology]

Fig. 2 is a block diagram showing a protective relay device for a busbar system to which _a conventional fuse blown detection device is applied. In Fig. 2, A, B, and C are protected three-phase system transmission lines, CT _B and CT _C are transmission lines A, B,
Current transformers installed in each phase of power line C, F _A , F _B , and F _C are fuses to be detected, and voltage transformers PT _A , PT whose primary sides are connected to each phase of power transmission lines A, B, and C. _B , connected to the secondary side of _PTC . CB is a disconnector installed on transmission lines A, B, and C.

1 is a fuse blown detection device, which detects the three-phase voltage Va,
Composite transformers T _A , T _B , T _C for deriving the zero-sequence voltage V ₀ by inputting Vb and Vc, and whether the zero-sequence voltage V ₀ is greater than or equal to a predetermined value (for example, 10% of the rated voltage). The output of the zero-sequence voltage detection element OVG, the zero-sequence current detection element OCG that detects whether the zero-sequence current _I0 is greater than or equal to a predetermined value (for example, 10% of the rated current), and the zero-sequence voltage detection element OVG. It is constituted by an inhibit (INHIBIT) circuit IN-1 as a logic circuit which has the positive input as the positive input and the output of the zero-sequence current detection element OCG as the inhibit input.

DZ is a protective distance relay for power transmission lines A, B, and C, and when a failure occurs in the transmission line, it outputs a trip command to cable breaker CB. In addition, power transmission lines A, B, C
voltage transformer with load current flowing through it.
If at least one of the secondary fuses F _A , F _B , and F _C of PT _A , PT _B , and PT _C blows out, it is assumed that a fault has occurred in the power transmission line, and the distance relay DZ responds unnecessarily. A trip command will be output to the disconnector CB.

Therefore, in order to prevent unnecessary response of the distance relay DZ as described above, when the fuse blown detection device 1 is activated, an alarm is issued to the outside and the distance relay
Connected to automatically lock DZ.

Next, the operation of the fuse blown detection device will be explained. When the detected fuses F _A , F _B , and F _C are all normal, the three-phase voltage Va,
Vb and Vc are balanced at a healthy rated voltage, and the zero-sequence voltage V ₀ is zero.

However, for example, voltage transformers PT _A , PT _B ,
When a short-circuit fault occurs in the A and B phases on the secondary side of PT _C , the fuses F _A and F _B are blown, resulting in a zero-sequence voltage V ₀ and the zero-sequence voltage detection element OVG is activated. do. On the other hand, since no ground fault has occurred on grid transmission lines A, B, and C, the zero-sequence current I ₀ is zero,
Zero-sequence current detection element OCG is inactive. Therefore,
Inhibit circuit IN-1 outputs fuse blown detection.

Also, it is not a blown fuse, but a
Even if a one-phase ground fault occurs in B and C, the zero-sequence voltage detection element OVG will operate, but at this time, a zero-sequence current I ₀ will occur and the zero-sequence current detection element OCG will also operate. No output of fuse blown detection is generated from the inhibit circuit IN-1.

[Problem that the invention seeks to solve]

Since the conventional fuse blown detection device is configured as described above, among the fuses F _A , F _B , and F _C ,
If one phase or two phase fuse is blown, zero-sequence voltage V ₀ is generated and the fuse blown is detected.
When the fuses of all three phases are blown, there is a problem in that zero-sequence voltage V ₀ is not generated and cannot be detected.

This invention was made to solve the above problems, and it is possible to reliably detect a blown fuse not only in one phase or two phases, but also when all three phases are blown. The purpose is to obtain a highly sensitive fuse blown detection device.

[Means for solving problems]

The fuse blown detection device according to the present invention is a first circuit that derives a maximum instantaneous value output from the output of a three-phase half-wave rectifier circuit connected to the secondary side of a voltage transformer of a system bus.
The maximum instantaneous value output is derived from the maximum circuit of 2 maximum circuits 2 are provided,
A comparison circuit is provided which compares the outputs of both of the maximum circuits and detects a blown fuse of the detected fuse.

[Operation] The comparator circuit of the fuse blown detection device according to the present invention operates on the condition that the output of the second maximum circuit becomes smaller than the output of the first maximum circuit, and the differential voltage between the two outputs exceeds a predetermined value. , detects that at least one phase of the detected fuse is blown.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In Figure 1, A ₀ , B ₀ , C ₀ are three-phase buses of the system, PT _A0 , PT _B0 , PT _C0 are voltage transformers installed on the buses, and fuses F _A0 , F _B0 are installed on the secondary side. ,F _C0
is provided. A ₁ , B ₁ , C ₁ are bus lines A ₀ , B ₀ ,
A power line connected to C ₀ with a current transformer in each phase of it
CT _A1 , CT _B1 , and CT _C1 are provided. PT _A1 ,
PT _B1 and PT _C1 are voltage transformers whose primary side is connected to the power transmission line, and whose secondary side is the fuse to be detected F _A1 ,
F _B1 and F _C1 are provided. CB ₁ is a line disconnector installed on the power transmission line on the system bus side from the voltage transformer connection point, DZ is a distance relay for the power transmission lines A ₁ , B ₁ , and C ₁ , and 11 is a fuse rupture detection device.

The fuse blown detection device 11 is a first three-phase half-wave rectifier circuit connected to the secondary side of a bus voltage transformer.
a first maximum circuit MAX-0 that derives the maximum instantaneous value output from the output of REC-0; a second three-phase half-wave rectifier circuit REC-1 connected to the output side of the detected fuse of the power transmission line; 3-phase half-wave rectifier circuit REC-1
a second maximum circuit MAX-1 that derives the maximum instantaneous value output from the output of the first maximum circuit MAX-1;
Comparator circuit COM-1 outputs when the difference voltage between 0 and the output of the second maximum circuit MAX-1 is greater than a predetermined value.
It consists of

Under normal operating conditions, voltage transformers PT _A0 , PT _B0 ,
PT _C0 , PT _A1 , PT _B1 , PT _C1 , first and second maximum circuits MAX-0, MAX-1, comparison circuit COM-1
The detection sensitivity of the comparison circuit COM-1 is set to about 10% of the rated voltage so that the comparison circuit COM-1 does not output unnecessary output due to its own detection error.

Next, the operation of the fuse blown detection device according to the present invention will be explained. When the system is healthy and the detected fuses F _A1 , F _B1 , and F _C1 are normal, the first maximum circuit MAX-0 and the second maximum circuit MAX
-1 outputs are all the same at the rated voltage, and no fuse blown detection output is generated from comparator circuit CM-1.

If the two-phase fuses of the detected fuses F _A1 and F _B1 are blown, the output of the first maximum circuit MAX-0 connects to the rated voltage, but the detected fuses F A1 and F _B1
The second maximum circuit connected to the output circuits of F _B1 and F _C1
As for the output of MAX-1, since the voltages of the A phase and B phase become zero, a fuse blown detection output is generated from the comparator circuit COM-1.

Next, if all three phases of the detected fuses F _A1 , F _B1 , and F _C1 are blown, the maximum circuit MAX-1
Since the outputs of phase A, phase B, and phase C are all zero, the comparator circuit COM-1 generates a fuse blown detection output.

Rather than a blown fuse, for example, power transmission lines A ₁ , B ₁ ,
If an A-phase 1-wire ground fault occurs in _C1 ,
maximum circuit MAX-0, second maximum circuit MAX-
Since the output of 1 decreases in exactly the same way, the comparator circuit
No fuse blown detection output is generated from COM-1.

In the above embodiment, the disconnection of the fuses F _A1 , F _B1 , F _C1 on the secondary side of the voltage transformers PT _A1 , PT _B1 , PT _C1 of the power transmission lines A ₁ , _{B 1} , _{C 1} is detected. As explained above, even when a large number of power transmission lines are connected to the bus lines A ₀ , B ₀ , and C ₀ , by sharing the output of the first maximum circuit MAX-0 of the bus line, other power transmission lines The present invention can be easily expanded to detect disconnection of a fuse to be detected on the secondary side of a voltage transformer.

〔Effect of the invention〕

As described above, according to the present invention, the maximum instantaneous value output of the three-phase half-wave rectifier circuit on the output side of the detected fuse of the power transmission line drawn out from the grid bus is the secondary voltage transformer of the voltage transformer of the grid bus. The structure is configured to detect a blown fuse on the condition that the output is smaller than the maximum instantaneous value output of the three-phase half-wave rectifier circuit on the side.
This has the effect of providing a highly reliable and highly sensitive fuse rupture detection device that can detect not only one-phase and two-phase fuse rupture but also all three-phase fuse rupture.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a blown fuse detection device according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional blown fuse detection device. A ₀ , B ₀ , C ₀ are system bus bars, PT _A0 , PT _B0 , PT _C0 ,
PT _A1 , PT _B1 , PT _C1 are voltage transformers, F _A1 , F _B1 ,
F _C1 is the fuse to be detected, A ₁ , B ₁ , C ₁ are the power transmission lines,
REC-0 and REC-1 are three-phase half-wave rectifier circuits, MAX
-0 and MAX-1 are the maximum circuits, and COM-1 is the comparison circuit. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1 A first 3-phase half-wave rectifier circuit connected to the secondary side of the voltage transformer of the system bus, and a first 3-phase half-wave rectifier circuit that derives the maximum instantaneous value output from the output of the first 3-phase half-wave rectifier circuit.
a second three-phase half-wave rectifier circuit connected to the output side of the fuse to be detected on the secondary side of the voltage transformer of the power transmission line drawn out from the above-mentioned system bus; A second maximum circuit that derives the maximum instantaneous value output from the output of the wave rectifier circuit, and the difference voltage between the output of the first maximum circuit and the output of the second maximum circuit have exceeded a predetermined value. A fuse rupture detection device comprising, as a condition, a comparison circuit for detecting a break in the fuse to be detected.