JPH0458135B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a blown fuse detection device, particularly to a blown fuse detection device on the secondary side of a voltage transformer of a power transmission line drawn out from a busbar system.

[Conventional technology]

Fig. 2 is a block diagram showing a protective relay device for a grid bus to which a conventional fuse blown detection device is applied. In Fig. 2, A, B, and C are the protected three-phase grid transmission lines, _{CT B} , CT _C are current transformers installed in each phase of transmission lines A, B, and C, F _A , F _B , and F _C are voltages whose primary side is connected to each phase of transmission lines A, B, and C. transformer
Secondary side detected fuses (hereinafter abbreviated as fuses) of PT _A , PT _B , PT _C , CB are power transmission lines A, B,
This is the breaker installed at 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 which has a positive input as input and an inhibit input as an output of the zero-sequence current detection element OCG.

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 melts, 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 fuses F _A , F _B , and F _C are all normal, the three-phase voltage on the output side of the fuses Va, Vb, and Vc
is balanced at a healthy rated voltage, and the zero-sequence voltage
V ₀ is zero.

For example, if a short-circuit failure occurs in phases A and B on the secondary side of voltage transformers PT _A , PT _B , and P _C , fuses F _A and F _B will melt, and therefore the zero-sequence voltage V ₀ occurs, and the zero-sequence voltage detection element OVG operates. on the other hand,
Since no ground fault has occurred in the grid transmission lines A, B, and C, the zero-sequence current I ₀ is zero, and the zero-sequence current detection element
OCG is inactive. Therefore, the inhibit circuit IN-1 outputs an output indicating that the fuse has blown.

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. The inhibit circuit IN-1 does not generate any fuse blown detection output.

[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 that the zero-sequence voltage V ₀ is not generated and cannot be detected.

This invention was made in order to solve the above-mentioned problems, and it is a highly sophisticated technology that can reliably detect a fuse blowout not only in one phase or two phases, but also in the case of all three phases. The purpose is to obtain a sensitive fuse blown detection device.

[Means for solving problems]

The blown fuse detection device according to the present invention includes a three-phase high-setting undervoltage detection element connected to the secondary side of a voltage transformer of a system bus, and a voltage transformer secondary side of a transmission line drawn out from the system bus. A logic circuit is provided to detect a fuse blowout based on the operating conditions of a three-phase low-settling undervoltage detection element connected to the output side of the fuse.

[Effect]

The logic circuit of the fuse blown detection device according to the present invention detects the fuse under the condition that all three-phase high-settling undervoltage detection elements are inoperative and one of the three-phase low-settling undervoltage detection elements is activated. Outputs disconnection detection.

〔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 grid buses, PT _A0 , PT _B0 , PT _C0 are voltage transformers whose primary side is connected to the grid bus, and F _A0 , F _B0 , F _C0 are voltage transformers. Fuses installed on the secondary side of transformers PT _A0 , PT _B0 , and PT _C0 ; A ₁ , B ₁ , and C ₁ are the first transmission lines drawn out from the system bus; CT _A1 , CT _B1 , and CT _C1 are the 1 power transmission line A ₁ ,
Current transformers installed in B ₁ , C ₁ , PT _A1 , PT _B1 ,
PT _C1 is a voltage transformer whose primary side is connected to the first transmission line, F _A1 , F _B1 , F _C1 are voltage transformers PT _A1 , PT _B1 ,
Detected fuse installed on the secondary side of PT _C1 ,
CB _A1 , CB _B1 , CB _C1 are the breakers for the first transmission lines A ₁ , B ₁ , C ₁ , DZ-1 is the distance relay for the first transmission lines A ₁ , B ₁ , C ₁ , and 11 is the fuse. This is a disconnection detection device.

The fuse blown detection device 11 receives three-phase high-setting undervoltage detection elements H _A , H _B , and _HC installed on the secondary side of the voltage transformer of the bus, and the output of the high-setting undervoltage detection element as input. The OR circuit OR-0, the low-settling undervoltage simulating elements L _A1 , L _B1 , L _C1 installed on the output side of the detected fuses F _A1 , F _B1 , F _C1 , and this low-settling under-voltage detection element OR with the output of as input
It consists of a circuit OR-1 and an inhibit circuit IN-1 which takes the output of the OR circuit OR-0 as an inhibit input and the output of the OR circuit OR-1 as a positive input.

The detection sensitivities of the above-mentioned high-setting undervoltage detection elements H _A , H _B , and _HC are set to about 0.8 times the rated voltage so as not to react to regular healthy voltage fluctuations, and the detection sensitivities of the low-setting undervoltage detection elements L _A1 , L The detection sensitivity of _B1 and L _C1 is set to approximately 0.7 times the rated voltage. The purpose of providing such a sensitivity difference is to ensure that when a failure occurs in the system and the L element operates, the H element can operate quickly and reliably.

Next, the operation of the fuse blown detection device according to the present invention will be explained. When the system is healthy and the fuses to be detected F _A1 , F _B1 , F _C1 are normal, the high setting undervoltage detection elements H _A , H _B , H _C of the busbar and the output side of the fuse to be detected are installed. low setting undervoltage detection element
L _A1 , L _B1 , and L _C1 are all inactive, and no fuse blown detection output is generated from the inhibit circuit IN-1.

If a two-phase fuse blown of the detected fuses F _A1 and F _B1 occurs, the low setting undervoltage detection elements L _A1 and L _B1 operate, and an output is generated in the OR circuit OR-1. On the other hand, the high-setting undervoltage detection elements H _A , H _B , and H _C on the busbar are all inoperative, and no output is generated in the OR circuit OR-0.
Therefore, an output indicating fuse blown detection is generated from the inhibit circuit IN-1.

Next, when all three phases of the detected fuses F _A1 , F _B1 , and F _C1 are blown, the low setting undervoltage detection elements L _A1 , L _B1 , and L _C1 operate, but the high setting undervoltage detection element H Since _A , H _B and H _C are inactive, an output indicating fuse blown detection is generated from the inhibit circuit IN-1.

No fuse blown, 1st power transmission line A ₁ , B ₁ , C ₁
If a system ground fault or short circuit fault occurs, the high-setting undervoltage detection elements H _A , H _B , and H _C operate in one phase or three phases depending on the fault type, and the OR circuit OR-0
Since the inhibit input is applied to the inhibit circuit IN-1 through the low setting undervoltage detection element L _A1 ,
L _B1 and L _C1 also operate, but the inhibit circuit IN−
1, no fuse blown detection output is generated.

In addition, in the above explanation, the first sending currents A ₁ , B ₁ ,
Although we have explained the case of detecting the fuses F _A1 , F _B1 , and F _C1 on the secondary side of the voltage transformers PT _A1 , PT _{B1 ,} and PT _C1 of C 1 , it is also possible to detect the blown fuses in other adjacent power transmission lines. To detect this, simply use the outputs of the high-setting undervoltage detection elements H _A , H _B , and H _C installed on the busbars and add a low-setting undervoltage detection element to the transmission line.
Fuse rupture detection can be performed.

〔Effect of the invention〕

As described above, according to the present invention, all the three-phase high-settling undervoltage detection elements installed on the system bus are inoperable, and the three-phase high-setting undervoltage detection elements on the output side of the detected fuse of the transmission line drawn out from the system bus are inoperative. It is configured to detect fuse rupture under the condition that any one phase of the low-settling undervoltage detection element is activated, so it is highly reliable as it can detect not only 1-phase and 2-phase fuse rupture but also all 3-phase fuse rupture. This has the effect of providing a highly sensitive fuse blown detection device.

[Brief explanation of the drawing]

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. H _A , H _B , and _HC are three-phase high-settling undervoltage detection elements, L _A1 , L _B1 , and L _C1 are three-phase low-settling undervoltage detection elements, and IN-1 is a logic circuit (inhibit circuit).
In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1 3 connected to the secondary side of the voltage transformer of the grid bus
a three-phase high-setting undervoltage detection element connected to the output side of the detected fuse on the secondary side of the voltage transformer of the transmission line drawn out from the system bus; a logic circuit that detects fuse rupture of the detected fuse under the condition that all of the phase high-settling undervoltage detection elements are inoperative and any one of the three-phase low-settling undervoltage detection elements is activated; Equipped with a fuse rupture detection device.