JPS6087618A - Reverse phase relaying device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a protective relay device that protects a power system, and particularly to a protective relay device that responds to negative sequence current.

[Technical background of the invention and its problems 1 Figure 1 shows an example of application of a conventional negative phase overcurrent relay. In the figure, 1 is a bus bar, 2 is a current transformer, and 3-1.3
-2 is a power transmission line. 4-1.4-2 are respectively power transmission 1!1
3-1. ．． The reverse phase overcurrent relay 7 is connected to the power transmission 13 - 2 via the current transformer 2 . Generally, other relays also maintain this system! However, since it is not necessary to explain the application of reverse phase faults, currents, and relays, it is not shown here.

In such a system, it is assumed that an accident occurs on the secondary side of the transformer 4-2, that is, on the distribution line 5.

In the case of a fault on the secondary side of the transformer 4-2, the fault current flows into the fault point via the transformer 4-2, and therefore has a much smaller value than the fault current in the power transmission line 3-2.

Therefore, there is no large difference in magnitude between the load current flowing through the power transmission line 3-2 when the system is normal and the load current including the fault current when the fault F occurs in the distribution line 5. In the case of such an accident, it is possible to detect this type of accident by using the negative sequence overcurrent relay 7, which operates based on the magnitude of the negative sequence current caused by the unbalance between the three phase currents, as shown in Figure 1. It becomes possible to do so. In other words, in this system, the negative phase overcurrent relay 7 is installed in the secondary distribution line 5 of the transformer 4-2 for the purpose of detecting an accident. As mentioned above, the negative sequence overcurrent relay 7 is for detecting a fault in the distribution line 5, but the minimum negative sequence current that needs to be detected as a fault in the distribution FA5 is, for example, 01A. In some cases, it is necessary to use reverse-phase overcurrent relays with Hatake sensitivity detection. In addition, the maximum value of the negative phase current is about 1△ at most, which is 5% for each phase current.
It will be about the size of A.

On the other hand, overcurrent relays for detecting transmission line faults are set at about 10A. Also, the error of the negative phase overcurrent relay, including the error of the current transformer 2, increases as the input current increases. Therefore, considering coordination with the above-mentioned overcurrent relay and including a margin, a wide linearity of up to about 12 A is required.

It is extremely difficult to secure such a wide linearity region and realize the high-sensitivity detection described above. The reason is that when trying to obtain linearity up to about 12"A, the voltage inside the relay becomes very small compared to 01A, which increases in detection sensitivity.
This is because it is affected by noise, and stable operation cannot be expected.

Furthermore, if the linearity region is increased to about 5A in order to have a hardware configuration that is resistant to noise, the above-mentioned error will increase rapidly due to the saturation of the operational amplifier, as detailed below.
There is a problem in that the negative phase overcurrent relay malfunctions at ~8A, causing problems in coordination with the overcurrent relay.

Therefore, the reason for the malfunction due to the sudden increase in error mentioned above will be explained below.

In the negative-phase overcurrent relay, it is necessary to extract the negative-phase component J to the three-phase input, and an operational amplifier is used for this lcth m-. It is known that the output voltage of this operational amplifier is saturated at about 70% of the power supply voltage.

Using such an operational amplifier, 3
When a phase balance current is input, the relationship between the input current of the buttock and the negative phase electrical quantity synthesized by the negative phase overcurrent relay is graphed as follows.
The result will be as shown in the figure. Here, 11 is the negative phase electrical quantity, 12
Is Pa □ reverse phase □ passing′-flowing? Indicates the operating limit level of the lf device. □ As shown in Figure I2, even if the input current is in the flat state, the current value of each phase increases by 1. When the operational amplifier becomes saturated, the negative phase electricity W increases rapidly, and the current value becomes 6. There is a disadvantage that the operating limit level of the reverse-phase overcurrent relay decreases, causing erroneous U operation.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and the purpose of (1) is to securely protect the protected area and prevent malfunctions.
An object of the present invention is to provide a negative sequence overcurrent relay device that does not malfunction.

[Summary of the Invention] In order to achieve the above object, the present invention provides an anti-phase relay that detects an anti-phase component or an amount of electricity related to an anti-phase component included in a three-phase current of an electric power system. This invention relates to a negative phase relay device 6 that locks the operation of a negative phase relay when the amount of other electricity obtained from the three-phase current exceeds a predetermined value. As for other electric quantities, the maximum value of the positive phase current and the three-phase input current (or the average value or the electric quantity related to these is used).

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. Third
The figure is a block diagram showing the configuration of one embodiment of the negative phase overcurrent relay device 6 according to the present invention.

In Fig. 3, 21, 22 and 23 are the three-phase current 1, respectively.
．． , I, and I□ are inserted into the relay. The three-phase current introduced into the relay 1. ,l
, and the electricity m IR, iy, and i, which are proportional to IT, are converted into positive phase electricity quantities by the negative phase current synthesis circuit 24 and the positive phase current synthesis circuit 25 and 12, respectively. 26-1.
26-2 is a full-wave rectifier circuit, 27-1.27-2 is a level detection circuit that outputs an output when the input exceeds a predetermined value, and 2
8 to 1.28-2 is a continuous circuit that serializes the output of the level detection circuit.

29 is the N07 circuit, and 30 is an AND circuit.

FIG. 4 shows an example of the configuration of the negative-phase current combining circuit 24, 7 and the if-phase current combining circuit 25, respectively.

Electrical IEI iR, ix and iT each have an input converter 21
, 22 and 23, and the electricity 1nL31, which is divided into phase currents I, , l, and 1-, has a phase shift of -120 degrees in electrical angle, and 32 has a phase shift of +120 degrees in electrical angle. The circuit 33 is an adder circuit that sums the electric quantity i and the outputs of the phase shift circuits 31 and 32.

Therefore, the output of the negative phase current combining circuit 24 is 124-1.
1:L20+1TH-20°, and this value becomes 1po1, which is proportional to the negative phase electric quantity, so that it can be easily used by the symmetrical coordinate method. Also, the output of the positive sequence current combining circuit 25 is i, -1-i
, ] 20 + i,d 20°, and this value is proportional to the positive-sequence electricity quantity.

Next, the operation of the negative phase overcurrent relay device of the present invention configured as described above will be explained.

In FIG. 5, 41 and 42 indicate the respective circuits of the iF 1k11 when three-phase balanced currents are input to the negative-phase current combining circuit 24 and the positive-phase critical combining circuit 25, which are configured as shown in FIG. shows the negative-sequence electrical quantity and positive-sequence electrical quantity that are the output of

43 and 44 are the negative sequence electricity quantity 41 and the positive sequence electricity quantity 4, respectively.
The detection levels of the level detection circuits 27-1 and 27-2 corresponding to 2 are shown. As shown in this figure, even if the three-phase input current is in a balanced state, when the current value of each phase increases, the saturation of the output of the operational amplifier used to extract the negative phase component causes the phase to be negative. The amount of electricity 41 increases rapidly. On the other hand, as the current of each phase (IC1) increases, the positive-sequence electricity quantity 42 increases in proportion to this, and eventually reaches a constant level in the saturated state.Therefore, as shown in FIG. If the level is set to the detection level 44 shown in FIG. 5, the level detection circuit 2
7-2. Continuation circuit 28-2. NOT circuit 29. and a state in which the output of the negative phase electric quantity side is blocked by the AND circuit 30 (<).

The characteristic of the negative phase overcurrent relay when the operation is blocked in this way is shown by the line 45 in FIG. The straight line 45 is a line that accepts the limits of the characteristics of the negative phase overcurrent relay. The dotted line in the figure is the conventional characteristic. Further, line 46 indicates the setting value of the overcurrent relay.

As can be seen from Fig. 6, this characteristic eliminates the need for a wide linearity region that was conventionally necessary, and also makes it possible to reliably detect accidents within the protected region! , b.

Note that 40 is the negative phase electricity quantity at the time of the accident, and the AND line 1'1 with the positive sequence electricity quantity at the time of the accident (not shown) is established, so
The reverse phase relay operates normally (there are no problems).

As explained above, according to this embodiment, there is no need to coordinate with other relays, and a sensitive reverse phase overcurrent relay device can be easily realized.

FIG. 7 shows a block diagram of another embodiment of the present invention. This is an example of the construction of an electric device for suppressing negative phase current and negative phase current. In FIG. 7, the same parts as in FIG. 3 are denoted by the same reference numerals and their explanations will be omitted.

34 is a smoothing circuit for smoothing the positive-sequence electricity quantity that has been full-wave rectified by the full-wave rectifier circuit 26-2, and 35 is a 5V smoothing circuit 3.
4 is a setting circuit that sets the output to a predetermined magnitude, and 36 is a setting circuit 35 that sets the output of the full-wave rectifier circuit 26-1 to the negative phase electric quantity.
This is a determination circuit that sends out a signal when the difference in positive-sequence electrical quantity, which is the output point of the signal, is a constant value.

The operating characteristics of the negative phase overcurrent relay 19 configured as described above are constant, determined by the setting value of the setting circuit 35, as shown by α in FIG. It becomes a straight line with a slope of .

Even in a reverse-sequence overcurrent relay device with such characteristics, as shown in Figure 5, when the input current increases, the amount of reverse-sequence electricity, which is the operating amount, increases rapidly. Since the positive phase electricity W, which is the amount of suppression, is constant, the influence of coordination or noise is a problem as in the previous embodiment. however,
As shown in FIG. 7, the level detection circuit 27-2. Continuation circuit 28
-2. NO■Circuit 29. Theory 11! When the positive sequence electricity amount exceeds a predetermined value due to the product circuit 30, as mentioned above, NO
The output of the T circuit 29 becomes "O" and the operation limit becomes 11~/
Therefore, the characteristic at this point becomes as shown in FIG. 8 β, and the above-mentioned problem can be solved.

Smoothing circuit 3/1 for suppressing negative sequence current. Setting circuit 3
5 and the determination circuit 36 are provided in order to improve the detection accuracy of the reverse phase relay.

In addition, in the above explanation, the positive-sequence electric quantity was used to prevent the operation, but the present invention is not limited to the positive-sequence electric quantity; for example, the maximum value or the average value of the three-phase input current. Even if the detection level is 1L, there is no problem as long as each detection level is determined as shown in FIG. 544.

[Effects of the Invention] As explained above, according to the present invention, the amount of electricity corresponding to the magnitude of the load current in the grid is detected, and when this magnitude exceeds a predetermined value, the operation of the relay is blocked. With this configuration, it is not necessary to coordinate with other relays, and a highly sensitive reverse phase relay device can be realized.

[Brief explanation of drawings]

Fig. 1 is a system diagram for explaining an application example of a negative phase overcurrent relay, Fig. 2 is a diagram for explaining problems of the conventional technology,
FIG. 3 is a block diagram of the -* embodiment of the present invention, FIG. 4 is a block diagram of the negative-sequence current combining circuit and positive-sequence current combining circuit of FIG. 3, and FIG. 5 is a detailed explanation of the present invention. 6 is an operational characteristic diagram shown in FIG. 3, FIG. 7 is a block diagram of another embodiment of the present invention, and FIG. 8 is a diagram of another embodiment of the present invention shown in FIG. 7. FIG. 1...Bus bar 2...Current transformer 3...Transmission line 4...Transformer 5...Distribution line 6...1ru3 7...Reverse phase overcurrent relay 11...Reverse phase Electricity amount 12...Operating limit level 21. 22. 23... Input converter 24... Negative sequence current synthesis circuit 25... Positive sequence current synthesis circuit 26... Full wave rectifier circuit 27... Level detection circuit 28... Continuation circuit 29...・N0I-Circuit 30... Theory l! l! Product I!
J1 path 31.32...Phase shift circuit 33...Tightening circuit 34...Smoothing circuit 35...
Setting circuit 36... Judgment circuit 41... Negative phase electricity amount
42... Positive sequence electricity amount 43, /14... Detection level 45... Operating characteristics of negative phase overcurrent relay 46... Excess w
I flow [F device operating characteristics

Claims (4)

[Claims] (1) In a reverse-phase relay that detects a reverse-phase valve included in a three-phase lightning current in a power system or an electrical outlet related to a reverse-phase valve, the reverse phase component obtained from the three-phase current or the reverse phase A means for producing an operating output when the other voluminous volume related to the valve exceeds a predetermined value, and a circuit for blocking the operation of the reverse phase relay by the output of this means. A reverse phase relay device characterized by the following. (2) The negative phase relay device according to claim 1, wherein the other quantity of electricity obtained from the three-phase current is related to the positive-sequence current and is an IC quantity of electricity. (3) The other quantity of electricity obtained from the three-phase current is the quantity of electricity related to the maximum supply among the three-phase currents.Claims &!
The negative phase relay device according to item 1. (4) The negative phase relay device according to item 1, wherein the other quantity of electricity obtained from the three-phase current is a quantity of electricity related to the average value of the three-phase current.