JPS5846824A - Protective 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 improving the protection performance of a protective relay device, particularly a two-line protective relay device. .

Among these, the carrier protection relay system is often used for reverse power lines, where the probability of system failure occurring is highest, in order to minimize the range of power outages by detecting faults reliably and eliminating faults.

FIG. 2 is a diagram showing the principle of a transport protection relay system using a current phase comparison relay. In the diagram, A and B are the busbars of both electric stations.
L is the power transmission line, IA% IB is the instrument current transformer installed at the Maimaryo electric station. The subscript ``B'' is used to distinguish the same equipment or mining equipment installed at both electrical stations, and the gender will be omitted in the following explanation. Reference numeral 2 denotes a current phase comparison relay (hereinafter referred to as a phase comparison relay), 3 a signal transmission device for transmitting current information to each partner electric station, and 4 an antenna for transmitting and receiving signals. This is one of the well-known nine protection membrane systems.In the event of an external accident, the current flowing from one end of the transmission line shown in Figure 5 will be transferred to the other end. In contrast, when there is an internal failure, current flows in from both terminals, that is, both terminals are 0CT in the above two types of faults.
As shown in Fig. 3, the phase relationship of the secondary current wire II+ is as shown in Fig. 3. When an internal fault occurs, t1 is in phase...(a) When an external fault occurs, the phase is reversed......(b) Fig. Hikoru. Therefore, if the currents at both terminals overlap in terms of phase, it is determined that it is an internal fault, and if there is no overlap, it is determined that it is an external fault, making it possible to reliably detect a fault within the protection zone.

In this case, it is necessary for one electric station to know the current information of the other electric station, and for this purpose, the above-mentioned signal transmission device and transmission line are required. FIG. 1 shows the case in which microwaves are used for signal transmission. On the other hand, FIG. 2 shows a case in which a power transmission line is used as the signal transmission path, which is referred to as energized power line transport. 5A, 5 in the figure
B is a coupling device for transmitting current information onto the power transmission line,
The other devices are the same as those shown in FIG.

In general, in the case of one type phase comparison relay using microwave,
A so-called phase comparison relay system is adopted in which current information corresponding to each phase of a three-phase alternating current is sent and received, and each phase is individually determined.

However, even in microwave transmission, when there is a limit to the amount that can be transmitted due to the frequency band, or when power line transmission is used for economic reasons, there are cases where three-phase current information cannot be transmitted individually.

In such a case, synthesize one representative current amount (this f: sample amount) from the three-phase current amounts,
This is used to protect a three-phase AC system, a so-called sample phase comparison relay type.

In this case, various combinations of sample sizes are usually used, but it is difficult to obtain a sample size that can be said to be perfect against all failures.

As an example, a sample amount based on a combination of a positive-sequence current It and a negative-sequence current It among symmetrical currents constituting a three-phase alternating current will be explained.

(1) Sampling amount with C phase as the reference phase Let's consider how the sample amount "t(a)" changes in the event of various accidents when the reference phase is one phase. However, the load current is ignored. .

It(-= Iza+ ”' ・・・-・=−−−lit
Here, the subscript a indicates the amount of electricity based on the C phase. K is a coefficient that indicates the ratio of combinations.

■Two-phase short circuit fault (in this case, I = 11)
I, CI, c) is the reverse phase current based on the b phase (C phase). 11b (■1e) is the positive sequence current based on the b phase (C phase). Ia # Ib # Ic is the fault phase current.

1, l is the vector operator t and f.

Looking at equation (2), it can be seen that the sample amount when two phases are shorted changes depending on the KO value, and also changes depending on the failed phase even for the same value of K. By the way, if = 1,
When the be phase is short-circuited, the sample amount for the C phase reference becomes zero, and no matter how large the fault current flows through the system, it will not be possible to insure the system. This is commonly referred to as a blind spot.

■L-phase ground fault (in this case, II = It = 't
o) In this case, although the sample amount does not disappear depending on the value of K as in the case of the two-phase short circuit described above, the detection sensitivity changes depending on the failed phase, as in the case of the two-phase short circuit.

For two-phase ground faults, the calculation is complicated because the shunt from the positive phase circuit to the negative phase and zero-phase circuits changes complicatedly depending on the negative phase and zero-phase impedance of both sides, but the sensitivity of the relay depends on the faulty phase. It is the same as above that the changes occur, and the cases where the above-mentioned blind spot appears will increase.

FIG. 4 shows a positive phase component synthesis circuit when the 4Ca phase is used as a reference. In the figure, 6m and 7m each have an input signal of 128.24
The phase shift circuit 8m for advancing the phase by 0° is an adder circuit, and its output 9a corresponds to the positive phase component of the a-phase reference. This is a well-known basic formula % Formula % Incidentally, the negative phase component can also be synthesized by a similar circuit using a phase shift circuit according to the above relational expression.

FIG. 5 is a block diagram of the sample amount synthesis circuit, 21 is a positive phase synthesis circuit, 22 Fi is a negative phase synthesis circuit, and the output n% 24 of each is introduced into the adder circuit section. This output 26 corresponds to the sample t(C) based on the above-mentioned combination of positive phase and negative phase.

By the way, recently there has been a tendency for companies to rely on it as a protection system. This is configured so that two sets of the same type of equipment are installed, and the circuit breaker is tripped at the OR of the two equipment.
This is a redundant design concept that aims to provide reliable protection with other devices even if one device becomes inoperable for some reason.

Below, we will consider the case where two sets of sample quantity phase comparison relay devices are installed based on the above idea.

The above-mentioned sample amount was based on the a-phase as the reference phase. We will examine below how the sample amount I with bs' as the reference phase changes in response to the failure type and failure phase.

(2) Specimen amount based on b-phase First, a symmetric component synthesis circuit based on b-phase will be explained. FIG. 76 shows a positive phase component synthesis circuit when the reference phase is the t-b phase, and is based on the well-known basic formula Ibt=★(Ib+aI'e order j tom Ia). It is exactly the same as FIG. 4 except that the subscript "S" indicates the b-phase reference.

That is, the hardware of the symmetrical component synthesis circuit is exactly the same, and only the phase order of the three-phase input currents is sequentially rotated.

■2-phase short circuit fault (l1=-1s in this case) 5) ■1-phase ground fault (Is = Is = I・) where (
Comparing the results of Equation 21 and 15) and the results of Equations (3) and (6), for example, in Equation (2), the bc phase short circuit in which the sample amount disappears at =1 is ( In Equation 51, it becomes the sample amount.

This means that if you prepare two sets of sample amounts, one with a symmetrical component based on an arbitrary phase and the other with a symmetrical component with another phase as the standard, both will compensate for the size of each other's sample amounts. This means eliminating the blind spots mentioned above.

The present invention has been developed to solve the above-mentioned problems, and an object of the present invention is to provide a redundant secondary protection relay device so as to improve the reliability of the protection relay device.

The actual IIkf4ftWi will be explained below with reference to the drawings.

The OFF diagram is a circuit configuration diagram of an embodiment based on a non-firing WAK.

In the off-line diagram, 2m and 2btl are sample amount synthesis circuits using symmetrical components with the a-phase reference and the b-phase reference, respectively.

The hardware of the synthesis circuit is exactly the same as the circuit shown in Figure 5, and for circuit 2b, the introduction of input current is 76
Rotate the phase sequentially as shown in the figure, and then
is configured to obtain.

Using the two sets of sample quantities with different reference compatibility in this manner, failure determination is performed independently according to the above-mentioned phase comparison principle, and the outputs of both are configured so that the disconnector 10 is disconnected by ORing.

By doing this, in the event of a failure, even if the sample amount of one set becomes zero or a value so small that it does not meet the sensitivity of the relay, there will be enough sample amount for the other set whose reference phase has been changed. As a result, the circuit breaker can be tripped reliably.

Up to this point, we have explained the sample size based on It Of course it is possible. Further, although the protection method has been explained using one type of current phase comparison relay, it goes without saying that it can be applied to any protection method using a sample amount.

The uninvented invention is that by using a sample amount that is a combination of symmetrical components, if only one set or two sets of equipment with the same sample amount are installed, the sample amount may disappear or become very large depending on the type of failure and failure phase. It is an object of the present invention to provide a protective relay device that can prevent a case from becoming too small to be shut off.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams for explaining the transport protection relay system, Figure 3 is a diagram for explaining the principle of phase comparison, the 4IQ positive phase component synthesis circuit, and Figure 5 is a sample. 6 is a negative phase component combining circuit, and the OFF diagram is a diagram showing an embodiment of the protective relay device according to the present invention. 1% lm, tB・・・−・・・Instrument current transformer 2.2 people, 2B, 2m, 2b-protective relay 3m, IB−・−・・−・・・－・・・・－・−・・
・Signal transmission device 4A%41...-1-...--...-
−・−・Antenna! A%5B...-1---1...Coupling device 646b%7a, 7b--
-----Phase shift circuit 8m, 8b ==-"-...
・−・−・・−・Adder 11b, 9b---
−−−−−−・−・・−1・・Symmetry output 10−−−−
---=”・-・−111 disconnection device 2 21&, 21b
・・・・＊dm+m@・・Positive phase component synthesis circuit 22, 228
%22b・・・－・－・・・・・・Reverse phase component synthesis circuit 2\2
3a, 23b...... Positive phase output 2 curses 24ζ 24b...-... Negative phase output 25.
25m, 25b...- Adder 26.
26m, 26b ・-------- II...A terminal, B terminal current transformer secondary current!
b%Ic...Each phase current L...--...--...Power transmission line.

Claims (1)

[Claims] In a protective relay device that utilizes the sample amount obtained by deriving symmetrical components from three-phase AC from the grid and appropriately combining these components, an optical A protective relay device configured to introduce and protect a sample amount, and a second sample obtained using a phase other than the reference phase used for the sample amount as a reference phase. and a second protective relay device configured to introduce a second protective relay device for protection, and trip the circuit breaker when either one of the first and second protective relay devices is activated. protective relay device.