JPS6013427A - Display line protecting 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] [Field of Application of the Invention] The present invention relates to a display line protection relay system, and in particular has a highly sensitive ratio differential characteristic that compensates for the influence of line constants that are distributed over the display line. The present invention also relates to a display line protection relay device that reduces the number of display lines used.

[Background of the invention]

As shown in Figure 1, the basic configuration of the conventional display line protection relay system is a current transformer CTA installed at both ends of the transmission line to be protected.
, CTB introduces a stain current, and exchanges current information at both ends through the display line PW, and displays the display line relays RYA and R.
This system comprehensively detects internal accidents using YB.

, A and B are busbars, and CBA and CBB are circuit breakers.

Various types of display line protection relay systems have been proposed in the past, but in order to explain the problems of these conventional systems,
The principles of representative examples will be explained below.

FIG. 2 is a diagram explaining the principle of a typical example. In this example,
The display line relay has a built-in base resistor Rh and a balance resistor, which is connected to the display line (one piece of the display line).

(assuming road resistance is R1) and connect as in the configuration shown in Figure 2. Here, the balance resistor R6 is a variable resistor, and if both ends are set so that Rp+R,=Rb...-(1), the secondary currents tA and iB of each end CT
The currents are divided into the R8 circuit and the Rb circuit at a ratio of 1:3.

In the same figure, the current arrow represents the current direction,
Each CT has an inflow current of 1. ,
．． The CT secondary current is configured to shift in the direction shown in the figure with respect to 1 pB. Therefore, Rh at the A end, R=
and Rb, 几 at the B end.

For each current flowing through, set the direction of the inflow current of its own terminal to be positive, f kb g l Am + ' i + b 1
If f Bg, then the transmission line internal fault current lpm+'lB
Against, 3,1.

1Ab=-s people+-tB ・・・・・・・・・(2)4
4 1, 1.

i,,=-tmu--tB ・・・・・・・・・(3)4
It becomes 4.

Now, assuming that the operating current of the display line relay is IO, the difference between the currents flowing through Rh and R, that is, (imbIA-) and (1+b-1!ts), is derived, and the suppression current is IR.
Assuming that the current flowing through Rs is derived, for the A-terminal relay and the B-terminal relay, it becomes.

Based on the above principle, if an accident occurs inside the protected area, the fault current will flow from both ends or one end, so no work can be done.
>With IR, the operation will operate reliably once the operation amount 0 is equal to the suppression amount IR. On the other hand, in the case of an accident outside the protected area, the fault current simply passes through and becomes 1A = -4B, and even if the error of the current transformers at both ends is taken into account, I o < I R, and the amount of suppression decreases. It once became officially inoperable.

The above principle can also be applied to a three-terminal system, an example of which is shown in FIG. In this case, protected areas A and B.

The reciprocating resistance from C to the branch end of the display line is J
i, R111B, and RIIIC, and the balance resistor explained in FIG. 2 is set as follows for terminals A, B, and C.

Rb=R−mu+Rp A=−・・・・・・α@R−b
=R-1+R1...(B)1%b =R
, c+R, c -"...02 or more, the operation amount IO? Suppression amount IR at each end is 1 at the A end with respect to the passing current. 1o = (iA+fB+iC) -...+...- +a
1.

IR= (21a-iB ic)---(11) 1 at the B end and 1 at the C end.

IB = -(2IC-1^-1B) ・・・・・・・・・
...(c), and it can be seen that it can be applied in the same way as the case of two terminals.

However, when applied to a three-terminal system, although the throughput operation amount 0 shown in equations Q3 to (g) is the same at each end, the suppression amount IR is not the same, so the following problems arise in application. there were.

That is, as shown in FIG. 4(a), one end inflow (A end) 1
In the case of one end flowing out (C end) and one end having no current (B end), the B end which is the no current end has a smaller amount of suppression than the other end (I RLD).
Formula H, (IG), m nioi c, A, C end tail
:jm=o, whereas at the B end it is 2t! 1=0. ), the ratio differential characteristics do not match at the end, as shown in the same figure (b).
Compared to the B end, the operating range of the ratio differential characteristics of the A and C ends is narrower. In addition, as shown in Fig. 5(a), in the case of two ends inflow (AC end) and one end outflow (B end), contrary to the example in Fig. 4, B Edge suppression amount Ill
However, the operating range due to the ratio differential characteristic of the B end becomes narrower than the other end.

As explained above, when the conventional method is applied to a three-terminal system, the ratio differential characteristics at each end are uneven depending on the fault current condition, and the operating range of the ratio differential characteristics is narrow, and there is insufficient In many cases, protection performance cannot be ensured. Furthermore, in the case of a 3-terminal system with 3 lines as shown in Figure 6, and some ends are out of service, the current flowing out from the branch end (B end) in the middle of an internal fault increases, and the conditions become synergistically severe. However, there will be cases where the system will not function due to an internal accident.

In addition, the current flowing through the display line is adjusted by the base resistor Rh and the balance resistor hole, but as the display line becomes longer,
Detection performance deteriorates when line constants other than resistance cannot be ignored. A method of adding the same characteristic impedance as the display line instead of the pace resistor, considering the compensation of the line constant (
There is also an example (Japanese Unexamined Patent Publication No. 50-151347), but since it deals with a circuit configuration including display lines, the dielectric strength and the mounting method for a multi-terminal system are complicated (for example, the constant of the display line may differ from the branch point). ) has the disadvantage of becoming

[Purpose of the invention]

In view of the above, it is an object of the present invention to provide a display protection relay system that can correctly derive the other end current at each terminal and match the performance.

[Summary of the invention]

In order to ensure the protection of multi-terminal branched power transmission lines, the present invention transmits current signals transmitted by display wires using a pair of display wires between each two opposing terminals. As a means of extracting only the information of the other terminal from the signal, a compensation circuit with simulated line constants of the transmission display line is provided, and the passing current signal of each terminal (9) is independently and faithfully derived, and the ratio difference is This invention provides a display line protection relay system using a current differential relay with dynamic characteristics.

[Embodiments of the invention]

An embodiment of the present invention will be explained with reference to FIG. The figure targets transmission line protection for a two-terminal system, but even if a multi-terminal branch power transmission line is protected, the number of opposing terminals will only increase, and it will basically be an application of Figure 7. Therefore, we will simplify the explanation using a two-terminal system.

The symbols and operation contents in FIG. 7 will be described below.

1 is a power transmission line to be protected, CBA and CBB are circuit breakers, the A terminal side is shown as CBA, and the B terminal side is shown as CBB. CTAs
, CTB are current transformers, CTA is used to input the power transmission line passing current waveform of the A terminal, and CTB is used to input the power transmission line passing current waveform of the B terminal to the protective relay devices RYA and RYB. The output current of CTA is indicated by im, and the output current of CTB is indicated by 11+. As already mentioned, the polarity of IM and 1B is set to be positive based on when a current of the same phase 'pk*ipB (10) flows in due to an internal fault current. C.T.I.A.

CT2A, CTIB, and CT2B are each auxiliary current transformers and are a type of isolation transformer.

Furthermore, since the contents of RYA and RYB will be explained using the operation of the A terminal as a representative example, the contents of the B terminal RYB will be omitted as appropriate. PW is a display line, i
This is a transmission line for mutually transmitting signals of A and iB. P.W.
γ, L, G shown in .

C is a distribution constant of PW, which is a symbol representing resistance, inductance, conductance, and capacitance, each having a unit of km M 9. R is a terminating resistor.

1. Tr is an isolation transformer for insulating the display line PW and the protective relay device BY. Double terminal current transformer CTIA
, CTIB to the other terminal are configured so that both are symmetrical, and values iA2 and iB2 proportional to the signals of iA and iB are transmitted from the respective protective relay device RY terminals by a pair of display lines PW. However, due to the influence of the distribution constants γ, L, G, and C of the display line PW, the signals reaching each other terminal are IA3 L iB3
(11) A signal proportional to iA+in is energized to the other terminal terminal resistor. The following explanation assumes that all current transformers are ideal current sources.

By the way, in the protective relay devices RYA and RYB, the signals of iA and iB are extracted isometrically as independent values,
For example, the ratio differential characteristic l i,+iBI KR(l iAl+ l iB l
)>K−...The aim is to make a determination that satisfies αO. However, KR is the suppression coefficient %Km is the level determination setting value.

However, when looking at the protective relay devices R and YA at the A end, the current passing through the terminating resistor R is iAl and iB3, and i
Al is a value proportional to own terminal input signal iA, 'AI=iA
tA, . The same is true for RYB, and the currents flowing through its terminal resistor R are iBl and IA3, and iB!
=iB−iB2. In this way, originally one person and i,
Alternatively, one should compare iBl or IA3 and iB3, but in the conventional display line protection relay device, the determination is made using the αO formula based on different combinations of signals. Here, each signal can be defined according to (12) below.

However, Kt, 2, and Ks are proportional constants,
It has the content of a complex number. As is clear from this, among the signals obtained at the A terminal, the value proportional to the B terminal current iB is iB3, and in order to extract only this, the current passing through the terminal resistor R of the A terminal must be iA1 + fB3 Just subtract 1 minute of IA from. For this purpose, it is necessary to know the value of %'AI.

Since iAl changes depending on the influence of the distribution constant of the display line PW, it is necessary to include the terminal resistance R and the distribution constant in its calculation. The present invention includes a simulation circuit that simulates the distribution constant of the display line PW and applies a self-terminal current.

In RYA, CT2A is the auxiliary current transformer used for the simulation circuit, ZJ,! I is the simulated line constant (13) of PW, and R is the terminating resistance. zAll is determined according to the length of PW, and for simplification, it is a resistance.

A T-type equivalent circuit or a π-type equivalent circuit consisting of a capacitor can also be used. Self-end current iA is applied from CT2A to ZAB, and as a result, the signals t, 11 IA2. Value iAl'+i equivalent to IA3
A2' + '13' can be obtained without including 130 terms, respectively. Therefore, from the secondary side signals of CTIA and CT2A, 'B3=tAI+1B3-i person!' is obtained by the difference circuit. ／ 、、、、、、、
, (2) can be obtained. Also, CT
Since iA3' of 2A is equivalent to iA3 generated by CTIA, iB3 and iA3' obtained by equation (c) provide the ratio characteristic of the aO type phase sound due to signals proportional to iB and iA, respectively. It is possible to make a judgment with

That is, in , the operating condition of the protective relay device RYA is (14) IA3'+1B31 Kn(lL3'l+In31)>
K (23) By dividing and correcting the throat, K, by a constant Ks', a determination formula equivalent to the formula C1' can be obtained. DTA in FIG. 7 is an arithmetic unit corresponding to equation (C). The arithmetic unit of the DT system may determine whether or not there is an operational output based on the results of calculations performed on the instantaneous values of iA and iB, but it is also possible to determine the presence or absence of an operational output based on the vector quantity that takes into account the amount corresponding to the effective value of iL + i1 and the phase angle. You can also do that. Also, R and YB are the same as RYA, and each is D.

It has arithmetic units DB and DTi+ corresponding to DTa. As an example of the present invention, we have shown a two-terminal system in which an internal accident is determined at each terminal. It can also be applied to protection methods that send commands.

In addition, in the protection of not only two-terminal systems but also multi-terminal branch power lines with three or more terminals, the current information of each opposing end should be transmitted between the opposing ends (15) according to the content explained in Figure 7. If we can obtain this, we can realize a ratio differential relay for a multi-terminal system.

However, in a multi-terminal system, there are multiple opposing ends, and the length of the display line PW to each opposing end may be different. A line constant may be additionally connected to the FW so as to match the length of PW, and a circuit corresponding to the simulated line constant Z&B may be added with each opposing line constant so as to match the longest PW.

FIG. 8 shows an embodiment in a three-terminal configuration. The symbols in this figure that are the same as those in FIG. 7 indicate equivalents. In the same figure, Z p ABI Z pACI Z p Bc
are the line constants of the display line FW between the A and B terminals, between the A and C terminals, and between the B and C terminals, respectively, and Z p Ai.

ZIIAC' and ZpBC' are respectively line constant compensation circuits for the above sections, and the line constant of PW is Z)ci+ZBs'=Zp input c-1-Zpac'=Zp
This is for adjusting so that nc+Zpn+c'=Zp...@. However, (1
6) Z is a line constant simulation circuit similar to Zhv in FIG.

The operation of this circuit in Figure 8 is explained by the protection relay device RYA at the A terminal.
To explain this using an example, from the B end to the isolation transformer ■・T,
The current iB3 taken into RYA through RYA and the A-terminal current i^ from current transformers C, T, and IA! are combined to obtain a current iAt + 183. Also, the current ic3 taken into RYA from the C terminal via the isolation transformer I-T.
and the current from current transformer CT2A are combined to produce current iA
Get 1+1c3. On the other hand, an A-end current iA is applied to the parallel circuit of the line constant simulation circuit Z and the terminating resistor R via the current transformer CT3A. Therefore, the line constant Z, B+
ZpAC, compensation constant Z'pin, Z'PA (!
and the simulated constant Z are selected so that the relationship of equation (c) holds, so the current i flowing through the terminating resistor R1
'A! is i^! in the composite current. be equivalent to. Terminal resistor R
Current flowing through 2 11. is equal to the current value i^3 when the own end current i1 is received by the other end via the display line PW. Difference circuit DA1. In DA2, I am! 10iB3 and i'mul
The difference between fit+"c3 and i', ! is derived (17) to obtain iI+3+ic3. The three sets of currents "&3+1113+'C3 input to the calculation unit DT are all expressed as "display aPW is a signal equivalent to the signal received by the other end via the Protection relay device R at B end and C end,
In YB and RYC, the same processing as the above-mentioned processing at the A end is performed to derive "the signal received at the other end and the isolateral force signal" for each end current. Therefore, by performing ratio differential calculation in the calculation unit DT at each end,
The operating characteristics of each end can be made to match, and the display line protection relay system can be made suitable for application to a multi-terminal system of three or more terminals.

The present invention can also be realized in the following manner. In the embodiment shown in FIG. 8, in the protective relay device RY at each end,
It is equipped with a circuit that simulates the line constants, but this is the 9th
As shown in the figure, a protective relay device BY having the same configuration as in Figure 8 is provided only at one terminal (terminal A in the figure), and a final judgment signal regarding disconnection of the breaker is sent to the other terminal (transfer trip method).

Furthermore, in this embodiment, a detection method focusing on the current (18) signal passing through the terminating resistor was shown, but in FIG. 10, the signal sent to PW of each terminal, IAI! .

1B3== using 'B3+ and i'A2 of the simulated circuit
te2 + I B3 1'A□ 10010991.
(c), i! +3 and i'A3 may be used to perform a ratio calculation that is compatible with the α9 formula.

In addition to simply scalar sum suppression, since the current at each terminal is obtained as independent information, it is also possible to compare the phase of each terminal current, use a maximum current suppression method, and identify non-power terminals, etc. It is also possible to identify the distribution of data, which widens the range of applications for accident detection.

In addition, 2/, mui+IZ'pmc, shown in equation (c),
The line constant simulation circuit of Z) does not necessarily simulate the distributed constant accurately, but it can be approximated by line resistance only, or an approximate constant circuit such as a T-type circuit or π-type circuit using line resistance and line capacitance, etc. It may also be carried out.

〔Effect of the invention〕

According to the above invention, a multi-terminal branch power transmission line can be protected by a device having a ratio (19) ratio characteristic using one pair of indicator lines per opposing terminal.

Further, the adjustment of the device can be performed for each pair of opposing terminals that transmit signals, which simplifies the adjustment work and improves the accuracy of adjustment.

However, since the number of display lines is small, there is an uneconomical effect, and since the current information of each terminal is detected individually, it has the effect of making it possible to set high sensitivity.

[Brief explanation of the drawing]

Figure 1 is a basic configuration diagram of the display line relay device, Figure 2 is an explanatory diagram of a conventional 2-terminal configuration, Figure 3 is an explanatory diagram of a conventional 3-terminal configuration, and Figures 4 and 5 are conventional diagrams. A diagram showing an example of the characteristics of
FIG. 6 is a diagram showing an example of dividing fault current inside a 3-terminal system, FIG. 7 is an embodiment of the present invention, and FIGS. 8 and 9 are embodiments in which the present invention is applied to a 3-terminal system. FIG. 10 is a diagram of another embodiment. CT...Current transformer, PW...Display line, BY...Protective relay device, R...Terminal resistor, DA...Difference circuit, Z,
...Line setting (20) 1st 20th 8γII K7B 32nd

Claims (1)

[Claims] 1. Differential calculation using as input a power transmission line, a current transformer provided at each end of the power transmission line, an indicator line installed between the current transformers, and an indicator line current flowing through its own terminal. In an indicator wire protection relay system consisting of a relay device that provides a protective output for the power transmission line, an indicator wire simulating part that simulates the line constant of the indicator line, and an indicator wire simulator that simulates the line constant of the indicator line, the A display line simulating section that provides a simulated output of the display line current flowing to the own end and the opposite end when the current transformer output is applied, and a simulated output of the display line current flowing to the own end of the display line simulating section. A difference deriving section that calculates the difference in the display line current flowing to the self-terminal of the display line is added, and the output of the difference deriving section and the simulated output of the display line current flowing to the opposite end of the display line simulating section are connected to the relay. A display line protection relay device characterized in that it is used as an input of the device. 2.0 terminal power transmission line, a current transformer provided at each end of the power transmission line, n sets of display wires each provided between the two terminal current transformers, and each display line current flowing to its own terminal. In a display line protection relay device comprising a relay device that provides a protection output for the power transmission line by differential calculation as an input, a line constant compensation provided on the display line in order to match the line constants of the n sets of display lines. circuit, a display line simulating part that simulates the line constant of the display line, wherein the output of the self-end current transformer is applied to the input section, and when this input is applied, the display line current flowing between the self-end and the opposite end is simulated. A display line simulating section that provides an output, a difference derivation that calculates the difference between the simulated output of the display line current flowing through its own end of the display line simulating section and the (n-1) set of display line currents flowing through its own terminal of the display line. The (n-1) difference outputs of the difference deriving section and the simulated output of the display line current flowing to the opposite end of the display line simulation section are input to the relay device. Display line protection relay device. 3. In the display line protection relay device according to claim 2, the display line simulating section, the difference deriving section, and the relay device are provided only in one terminal, and the output of the relay device of the one terminal is A display line protection relay device that transfers the signal to the other end and opens the breaker.