JPS5866528A - Ground-fault protecting relay unit - 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] The present invention relates to a ground fault protection relay device, and in particular, to a ground fault protection relay device suitable for ground fault protection when zero-sequence circulating current occurs in a multicircuit parallel transmission line of a resistance grounding system. Regarding protective relay devices.

In general, important power transmission lines are often configured as multi-circuit power transmission lines with two or more circuits as shown in FIG. 1 in order to improve the reliability of power supply.

In Figure 1, a multi-circuit power transmission line with resistance grounding system is shown.

~L4 is a breaker SB on the bus bar 10 of the power supply system 1.

~sB, 4, and are connected to the bus 20 of the load system 2 via breakers SB2. ~5B24, are connected to each other. The power supply system 1 is constructed by connecting a bus bar 10 to a power source 12 such as a generator via a transformer 11, and grounding the neutral point of the transformer 11 via a resistor 13. In addition, the load system 2 is
The m-line 20 is connected to a load 22 via a transformer 21.

In a multi-line power transmission line system configured in this way, the multi-line power transmission ATs 1 to L4 of the line resistance grounding system are often installed together on one tower, and the zero-sequence circulating current due to mutual induction between the lines is known to occur.

FIG. 2 shows an example of a four-circuit parallel power transmission line. In this figure, each line ~L4 has a load. In such a state, if a one-line ground fault occurs in any one of the transmission lines L1 to TJ4, in a resistance-grounded transmission line, the fault current will flow through the ground resistance of the neutral point of the transformer 11. 13
It is difficult to distinguish from the zero-phase circulating currents Icol to ICO4 explained in FIG. 2, and it is often impossible to determine internal/external faults with a simple earth fault direction relay. FIG. 3 shows an example of a parallel transmission line with four circuits in parallel, similar to FIG. 2, in the case of a - line ground fault. That is, when a ground fault occurs, the zero-sequence currents Io1 to Io of each line L1 to L4 on the bus 10 side in FIG.
4 is Accident Electricity #1. (Current flowing through the neutral point grounding resistor 13) IF, ~IF4, and zero-sequence circulating current Ico, ~■c
It becomes the sum with o4, I O4 = I Fl + Ic
ol-・・-・Q)102-T
F2 + Ico2-88. (2) 103-I F3
+JCO3--(3)T 04 = T F4 +Tc
o, + −・−・・・・(/l)
Dodoru. The original ground fault judgment is zero-sequence voltage V. This is done by identifying the magnitude and phase of the fault currents IFI to IF4, but as already mentioned, when the zero-phase circulating current 1cO5 to ]co4 cannot be ignored compared to the fault current, , the magnitude and phase of the current IFI~1F4 change due to the influence of these currents J'col~1CO4, which sometimes makes it impossible to make a proper accident determination. Various countermeasures against such external phenomena have been proposed in the past. As an example, focusing on the change in zero-sequence current before and after the occurrence of an accident,
A method has been proposed that extracts only the fault currents, TF1 to T++4, without being influenced by the zero-phase circulating currents, TCOI to ICO4, to determine a fault. This method will be described below.
1 to L4 zero-sequence current■. , ~Io4 is the zero-phase circulating current Tc
Only o1 to Tco4, I'o1= Icol
・・・・・・(5) I'o2-'
Ico2 ・・・・・・(6)I
'o3 = Ico3...
...(7) i. 4 = Ico4
, ----1(s), whereas after the accident occurs, it is given by equations (1) to (4) as mentioned above, so the value I'o before the accident occurs is 1 to I'o4
are stored for a certain period of time, and these I'o1 to I'o
4, and the value I after the accident occurs, which can be determined by equations (1) to (4).
The difference between o1 to Io4, that is, the change before and after the occurrence of an accident, is extracted for each line as shown in the formula below, and an accident is determined. That is, the changes ΔIo1 to ΔIo4 are as follows: ΔIo4-Io4 TO4=IF4+]'CO4Ic
o4-Jp4 H... (12). A specific example of a device that performs calculations in this manner is shown in FIG. That is, FIG. 4 is a block diagram showing a conventional example of a ground fault protection device.

In FIG. 4, the earth fault protection relay device is provided for each resistance-grounded multi-circuit transmission line in which zero-sequence current is generated, and receives the zero-sequence current ff:vo in each transmission line from the input terminal 30. Input the zero-sequence currents Io1 to Io4 to terminals 31 to 3
calculation means 41 to 44 for calculating the effective zero-sequence current of each line based on the signals taken in from 4;
It is comprised of a comparison circuit 5 as comparison means for determining an accident based on the effective zero-sequence currents from these calculation means 41 to 44. Since the calculation means 41 to 44 have the same configuration, these Mu means 41 to 44
To explain one of them, the effecting means 41 compares the instantaneous zero-sequence current input to the input terminal 31 and the zero-sequence current from the memory circuit 6 using the equation shown in equation (9). The comparator circuit 71 that operates and the zero-sequence voltage (■) taken in from the input terminal 30. and an effective component calculation circuit 81 which calculates the effective component zero-sequence current using the value from the comparator circuit 71. The other operation means 42 to 44 have storage devices 62 to 64, ratio circuits 72 to 74, and effective component calculation circuits 82 to 84, respectively.

The operation of the earth fault protection relay device configured as described above will be explained.

Zero-sequence current Io1-i of each line L1-L4. 4 input terminal 3
1 to 34, the vector quantities of the zero-sequence current are stored in each of the storage circuits 61 to 64 for a certain period of time, and then the instantaneous value of the input zero-sequence current and the storage circuit 61 are stored by each of the comparison circuits 71 to 74. .about.64 are compared with the stored zero-sequence current values, and the fault currents TFI to IF4 of formulas (9) to 12 are extracted.

~L4 fault current IPI~IF4 and zero-sequence voltage V introduced from zero-sequence voltage input terminal 30. From this, the effective division a circuits 81 to 84 extract the effective zero-sequence current of each line (the zero-sequence current of the in-phase component with VO), the results are compared by the comparison circuit 5, and the effective zero-sequence current The line with the largest value is determined to be the faulty circuit, and an output corresponding to the result is outputted from output terminals 91 to 94 for each line.

However, in a system such as the protective relay device, which is based on detecting a change and determining an accident, there are the following drawbacks. That is, in a parallel multi-circuit power transmission line as shown in Fig. 2, assuming a single-line ground fault on the bus 20 side, on the bus 10 side, (9) 2 to (12
Unless the fault currents IPI to IF4 extracted by the equation ) flow in parallel and create a difference between each line, there is a drawback that the fault line will be judged as 11. On the busbar 20 side, it is determined that rJ is normal.
3. ．． ．． Even after the circuit is cut off, the current distribution becomes as shown in Fig. 5, and only the fault current 11. flows in the fault line L1 bus 10 (+111), but the zero-sequence circulating current Tco.~I CO4 flows in the healthy line. , in the worst case, for example, 1F, evening ■ co2 (13), and even considering the changing current, f (20 on the line 20 side)
Also, 10I, with advance disconnection at the Ll end.

The disadvantage was that it was difficult to identify the faulty line at the end.

An object of the present invention has been made to eliminate the drawbacks of the prior art described above. For work! An object of the present invention is to provide a ground fault protection relay device capable of determining Jl failure.

The present invention provides an earth fault protection relay device that takes in the zero-sequence voltage of a multi-line power transmission line and the zero-sequence current of each line, calculates an effective zero-sequence current, and determines a faulty line based on the calculation result. The ground fault fault determination is controlled based on line load current (each phase current) conditions, and fault determination is performed without the influence of zero-sequence circulating current.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 6 is a block diagram showing an embodiment of the earth fault protection relay device according to the present invention. In the example of this figure, the fourth
Components that are the same as those in the figures are given the same reference numerals, and their explanations will be omitted.

The difference between the embodiment shown in FIG. 6 and that in FIG. 4 is as follows.
The load current ILI~D+, 4 of each line ~L4 is taken in through the input terminals 101~102, the presence or absence of the load current is determined, and it is determined that there is no load current among the load currents ILI~IL4. Line (one of Ll to L4)
In addition to controlling the operation of the arithmetic circuit (one of 41 to (9) 44) in the comparator circuit 5, the effective zero-sequence current from the arithmetic circuit other than the hii arithmetic circuit determined to have no current is transmitted to the comparator circuit 5. Level determination means 201 to 204 for each line L1
~L44ri.

The present invention is shown in FIG. IT continues to flow in the same state as before the accident, as shown in lines 2 to 1 and 4, and 20. ．． The load current is II because the first terminal has not properly determined the internal fault and cut off in advance.
By focusing on the point where OII occurs and no flow occurs, that is, the difference in the charge current f] between the faulty line and the healthy line, it is possible to properly determine whether the other end is a pre-break/break ground fault or an internal fault. In other words, lines with load current are flowing with zero-sequence circulating current, so in order to prevent erroneous judgments, the operation of the ground fault relay is prevented, and lines with no load current are cut off in advance of the other party. , it is determined that the zero-sequence current flowing in is only the fault current, and the internal operation is normal.

(10) This system is designed to determine a one-line ground fault accident.

Next, the operation of the embodiment of the present invention will be explained.

In addition, the load current (
In Figure 6, a single-phase circuit is shown, but in reality, in order to determine the three-phase load current conditions, a three-phase circuit is introduced from the input terminals 101 to 104 for each line, and the level The determination is made by determination circuits 201 to 204.

Here, when one of the level determination circuits 201 to 204 determines that there is no load current, the circuit in which the load current is determined to be zero among the vector memory circuits 61 to 64, which has already been explained in FIG.・Forcibly set the amount stored in the path to “0”
In addition, the load current level determination circuit 20
Outputs of the circuits 1 to 204 that have determined that there is no load current are introduced to the comparison circuit 5, and control is performed so as to prevent the determination of lines with 9 load currents. Note that when the storage capacity of the vector memory circuits 61 to 64 is forcibly set to "0" under the condition of no load current, in the state shown in FIG. 5, (11) Io1=I F -・
...(14)? o, (memory amount) → lI O11 (forced)
O") ... - ... (15) ΔIo1=Io11
'o1=jp Shouting...(It becomes t61, and it becomes possible to make a regular judgment based on the fault current.

In this way, by performing the determination control based on the load current condition according to the present invention, it is possible to determine an internal one-wire ground fault that is not influenced by the zero-sequence circulating current. Furthermore, as shown in Figure 2, since the load current normally flows in parallel to each line, it becomes Icol-α1, and since the zero-sequence circulating current has the following proportional relationship, Tr...
...(18) Ico2=α21□,
・・・・・・G wings. . 3-(! 3 Tr,
・・・・・・(2o)□C04= ”
4 T T-"Group 1") (However, α1.α2.α3
．． α4 constant [complex number]). Therefore, 11. There may be a case (12) in which the fault currents Ico1 to Ico4 are proportionally small and can be ignored in accident determination compared to the fault currents IFI to IF4. By applying this and selecting the levels of the level determination circuits 201 to 204 in FIG. 6, the storage capacity of the vector storage circuit is forced to ``0''.
As a result, it is possible to make a judgment by detecting the amount of change.

As described above, according to the present invention, the load current is taken in, the presence or absence of the load current is determined, and the calculation of the effective zero-sequence current of the line for which it is determined that there is no load current is controlled. Since the effective zero-sequence current of the line can be controlled to be excluded from the fault determination conditions, there is an advantage that fault determination can be made accurately without being influenced by the zero-sequence circulating current.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing the system configuration of multi-circuit transmission lines;
The figure is an explanatory diagram showing the distribution of zero-phase circulating current and load current in the system shown in Figure 1. Figure 3 is an explanatory diagram showing the current distribution at the time of an internal one-line ground fault in the same transmission line. A block diagram showing a ground fault protection relay device with countermeasures against phase circulating current, Fig. 5 is an explanation showing the current distribution when one end light line is cut off (13), and Fig. 6 is a ground fault according to the present invention. FIG. 1 is a block diagram showing an embodiment of a protective relay device. 41-44... Arithmetic circuit,... Comparison circuit, 61-6
4... Memory circuit, 71-74... Comparison circuit, 81-
84... Effective minute hand thrust circuit, 201-202... Level determination circuit. (14) Kuzu 3 zuyo 40? C

Claims (1)

[Claims] 1. It is installed in each resistance grounding multi-line power transmission line where zero-sequence current is generated, and captures the zero-sequence voltage in the transmission line and the zero-sequence current of each line, and calculates the effective component zero of each line based on these. In an earth fault protective relay device, which is equipped with calculation means for calculating phase currents and comparison means for determining faults based on the effective zero-sequence currents from these calculation means, the load currents of each line are taken in, and the load currents are Controls the computation of the computation means in the circuit for which it is determined that there is no load current among the circuits, and removes the effective zero-sequence current from the computation means of the circuit other than the determined circuit from the comparison target of the comparison means. A ground fault protection relay device characterized in that it is provided with a level determination means for controlling.