JPH0244267A - Apparatus for detecting disconnection of pt secondary circuit - Google Patents

Abstract

PURPOSE:To detect the disconnection on secondary side by judging whether predetermined relation is present between the phase voltages of three phases on a PT secondary side, line voltage and voltage phase differences between the phases and the line voltage. CONSTITUTION:An input part 4 receives voltage from a three-phase PTC and, when the magnitude of phase voltage is larger than a value epsilon1, detection circuits 5-7 emit outputs and, when line voltage is smaller than a value K, detection circuits 8-13 perform output operation. Phase difference judge circuits 14-16 perform output operation when each phase voltage is delayed by an angle epsilon2 from line voltage and voltage judge circuits 17-19 issue outputs when the line voltage is smaller than a value K2. PT secondary circuit disconnection detection signals S1-S7 are obtained through the operation means of AND circuits 20-22, AND circuits 23-25 wherein one of input terminals is a prohibiting terminal, an AND circuit 26 and an OR circuit 27. By this constitution, the disconnection of a secondary circuit can be detected from the outputs of one set of three-phase output circuits of PT and, even when there is other line load in the secondary circuit, the disconnection of the secondary circuit can be certainly detected.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a disconnection detection circuit 1ζ of a secondary circuit of a PT which is an input signal source of an example or a digital protective relay device, and particularly relates to a disconnection detection circuit 1ζ of a secondary circuit of a positive phase This invention is suitable for use in a protective relay device that synthesizes zero-phase XfL voltage from phase voltage.

[Conventional technology]

Figures 8 and 9 show, for example, the disconnection of the conventional PT (r [voltage transformer) secondary circuit] shown in [Protective Relay Engineering J P235-P236, published by the Tun Kei Gakkai on July 20, 1981. This is a detection circuit. (to) is a PT, a parent and child PT is used, and its output circuits are two sets (28A028B). (2
) is the In voltage balance relay (29b) is the output contact of this voltage balance relay, and (7) is the output circuit (to) of the PT (to).
Output relay group 1 (30a) receiving the output of 28A) is the contact point of the output of this output relay assembly (7).

Next, the operation will be explained. There are two sets of output circuits (28A) and (28B) for the PT (PT), and the output of one set (28A) is connected to the original device that uses it, such as an output relay.
J Lf (7) and one input terminal of the f[j applanation relay (to), and the remaining set (28B) is input only to the other input terminal of the voltage balance relay. do. Here, if the output of the PT (to) connected to the output relay device becomes an abnormal value for some reason (such as a wire breakage), a difference will occur between the two sets of inputs of the TI pressure balance. The difference is detected by the voltage balance relay (2) and notified to the outside, or the sequence shown in Figure 9 is set up, and the b contact (z9b) of the voltage balance relay (support) opens.
Even if the a contact (3Oa) of the output relay device ■ is closed, the a
The circuit of the contact (3OS) is not closed.

[Problem to be solved by the invention]

Conventional PT failure detection equipment is configured as described above, so two sets of output circuits (IA) and (IB) for PT (1) are used.
In addition, a voltage balancing relay (2) must be provided, which has disadvantages such as increased cost.

This invention was made in order to eliminate the drawbacks of the conventional ones as mentioned above.
The purpose of this is to enable detection of disconnection in the T secondary circuit.

[Means to solve the problem]

The P72 next-time edge detection device according to the present invention is provided corresponding to each phase, and receives input from three phases (A-phase, B-phase).
phase voltage determination means for determining whether or not each of the phase voltages VA, VB, and VC of the phase C phase and C phase is equal to or higher than a predetermined value of 61;
Each of B and VC is the negative phase voltage (e.g. VA)
Phase voltage line voltage amount phase difference determining means for each phase for determining whether the phase is delayed by a predetermined angle ε2 or more with respect to the line voltage between the other two phases (for example, Vsc); The corresponding phase voltage discriminating means and the phase voltage line-to-line 7 (y positive amount phase difference discriminating means) are provided so that the phase voltage of the corresponding phase is equal to or greater than a predetermined value ε1, and the phase voltage of the corresponding phase is The phase voltage of the line voltage of both other phases is at a specified angle ε.
A first calculating means that outputs a PT secondary circuit disconnection detection signal when the delay is two or more; a first line voltage determining means for determining whether the line voltage (e.g. VAB, VC) between the C phase and the C phase is less than or equal to a predetermined value of 1; In response to each output of the phase voltage determining means and the first line voltage determining means, if the phase voltage (for example, VA) of the corresponding phase is smaller than a predetermined value C1 and the voltage between the corresponding phase and both adjacent phases is A second circuit that outputs a secondary circuit disconnection detection signal of the PT when any of the line voltages (for example, VAB and VC voltages) is less than or equal to a predetermined value of 1.
The calculation means is provided corresponding to each of the three-phase line voltages VAII, Vsc, and VC input from the PT, and the corresponding line voltages are set to predetermined values! a second line-to-line constant pressure determining means for determining whether the line-to-line constant pressure is smaller than PT; a third calculation means for outputting a secondary circuit disconnection detection signal, and if at least one of the first to third calculation means outputs an output from the first to third calculation means, the PT This is a disconnection detection device for a PT secondary circuit, including a fourth calculation means that outputs a secondary circuit disconnection detection signal.

[Effect]

In the PT secondary circuit disconnection detection device fiIfifζ of the present invention, the phase difference between the three phase voltages, the line-to-line voltage, and the phase 1d line-to-line voltage is obtained from the secondary side of the PT, and these phase voltages, line-to-line voltages, F+1. It is designed to detect whether the PT secondary circuit is disconnected by determining whether or not the phase voltage, phase voltage, line voltage, phase difference, and line voltage phase difference are in a predetermined relationship. There is no need to provide two sets of three-phase output circuits for the PT, and there is no need to provide a voltage balance relay to compare the output ru voltages of these two sets of output circuits.
Disconnection of the PT secondary circuit can be detected from the output of the phase output circuit, and the 4.1 line of the PT secondary circuit can be reliably detected even when there is another line load in the PT secondary circuit.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (1) is the 3-phase power transmission line to be protected, (2) is the 3-phase bus of the substation to which the power transmission line is connected,
(3) is a three-phase PT (Li pressure transformer) that converts the bus voltage to a size that is easy to use for relay devices, etc. (4) is P
an input part of the device receiving voltage input from T, (5);

(6), (7) are the three-phase phase voltages VA, Va,
Phase 2 pressure detection means consisting of a circuit that outputs a signal when the magnitude of V( is larger than a certain value ε, (8), (9)
, QO, Ql), 03, o3 is a first line pressure discrimination means consisting of a circuit that outputs a signal when the three-phase line voltages VAB, VBC, and VC are smaller than a certain value K2, and α fathom is a vector. Phase voltage line voltage amount phase difference determination means consisting of a circuit that outputs a signal when VA lags VBC by an angle corresponding to t2, also shown in Tochi.

Qf) is a circuit that outputs a signal when Va lags VC and VC lags VAB by a certain angle (VAxVsc represents the cross product. That is, VAXVBC = IVAI ・1Vn
phase voltage line pressure phase difference determination means, αη, 0119
, 01 is VAn, VBC.

A second line voltage discrimination means consisting of a circuit that outputs a signal when the VCA is smaller than a certain value K2, made of copper, (I) is A.
First calculation means consisting of an ND circuit, ■, eI4. (2
) is AN where one of the three input terminals is INHIBIT @
The second arithmetic means consists of a D circuit, the third arithmetic means consists of an AND circuit, and the fourth arithmetic means consists of an OR circuit.
calculation means, SI + SI y SII + s,
j S5 + S6 r S7 is the PT2 next line disconnection detection signal.

Next, the operation will be explained, but before that, we will explain what happens to each voltage vector applied to the relay device when the secondary circuit of PT (3) is disconnected. PT 2
When the secondary voltage is a phase voltage, the relay device receives it as a phase voltage, but of course the secondary voltage of the PT is not only applied to the digital protection relay device, but also to various devices (meters, various measurement control devices, etc.) between the lines. Some of them are also used as line voltages. They are illustrated in Figure 2. In Figure 2, (1
) is the PTc)51 pressure generator, (2) is the relay device that is trying to detect the disconnection of the P7 secondary circuit, and is the other load between the lines. Now, as shown in Figure 3, when the output line 1 of the phase voltage Vm of the P7 secondary circuit is disconnected, the relay (
A certain voltage is generated in the phase 3 voltage input circuit 2) due to the wrap-around from the voltage of the other phase which is not disconnected as shown by the arrow. Of course, if there is no line load (3) in Figure 2, there is no loop circuit, so the phase voltage of relay (2) V
M becomes O. If the above is written in a vector diagram, it will look like Figure 4. That is, the phase voltage (1) is the impedance ratio of the relay (to the relay) and the other line load (to), and is located in the shaded area due to the difference in impedance of each phase. At this time, the vector relationship is clearly such that the phase voltage 7 lags behind the line voltage Vnc. The delay angle is -30° as shown in Figure 5.
--150°. To explain this relationship in detail in the present invention shown in FIG. Since there is an output signal from the delay determination circuit for the voltage Vmu and the line voltage VBC, a disconnection in one phase of H can be detected. In addition, when the absolute value of the phase voltage 1"V'Al is less than the predetermined value c1, that is, when there is no other line load and the phase voltage VA of the relay mill is 0, the line voltage V.A.B.
Ha is equal to the zo-phase voltage VB, and the line voltage VCh is equal to the phase 7α voltage VC. Therefore, the circuit (8
) (9) is output, making it possible to detect interruptions.

Detection of disconnection of one spring in other phases is also possible in the same way.

Next, the two-phase disconnection will be explained. As shown in Fig. 6, if the phase voltage Va and VC signal lines from PT are disconnected,
Phase voltage Va of relay equipment (A), disconnection in VC circuit,
The phase voltage Vm from the non-energized phase is applied via a loop circuit from another line load as shown by the arrow.

If you draw a vector diagram, it will look like Figure 7. That is, the phase voltage■
The rated voltage (for example, 63.5
V), and the other phase voltages VB and VC are in phase with the seven phase voltages and have values smaller than the phase voltage Vm. Therefore, line spacing 1
Voltage VAB, VBC, VC is 63.5 of the rated phase voltage
Therefore, if the predetermined value of the 1u pressure determining means (17), (g), and a9 in FIG. It becomes possible.

Next, examples of specific values of the constants (ε7.ε!, Kt, Kl) of each predetermined value shown in FIG. 1 of the embodiment of this invention are shown below.

The predetermined value ε1 is set to, for example, 3V, based on the idea that it is sufficient if the phase voltage is sufficient to allow direction discrimination. As shown in Fig. 5, the predetermined value C2 is such that the lag judgment is 30° or more, so if the margin is 10°, then in order to output a signal if the lag is 20° or more, ffz=IV module is set. fxlV
nclxsjnθ=3VX110VX 5in(-20
°) = -113. In addition, the specified value may be set to be higher than the rated voltage of the phase voltage, but the error of the relay is 5%.
, 1% error in PT, and up to 10% error when operating a t-power system.
% voltage rise, 615 x 1.06 x 1.1 = 74.04VFurthermore, if the phase voltage V is 3V, which is the predetermined value ε, then a
The tonnage pressure VAB and VC increase by cl, so 1 (7404+3 = 77.04V to the predetermined value)
=78V. The predetermined value is 2. Since the voltage between each line will be 615 V or less when the wire is disconnected, the error between the relay and n, the maximum Y [taking into account the pressure increase, > 63.5 x 1.06 x 1.1 = 7
It is preferable to set the predetermined value to 75V from 404V.

In addition, in the above-mentioned embodiment, the case where various PT secondary circuit disconnections are detected by the detection signal s7 was illustrated, but the detection signals s, , sl, s! only or sm l
54 *S, only, or S6 only, in which case S. .

Circuit to obtain S, , S, (7) Mi, or S, ,
There may be only a circuit that obtains S, , s, or only a circuit that obtains s6, or two such circuits may be combined as appropriate. Also, phase voltage detection and line voltage discrimination in the above-mentioned embodiments.

Any of the phase voltage line voltage amount phase difference determination and the first to fourth calculations may be processed by S/W using an electronic computer.

[Effects of the Invention] As described above, the present invention has three phase pressures V and VB provided corresponding to each phase and input from the PT.

The above-mentioned t is provided corresponding to each phase, a U pressure determining means, and a U pressure determining means for determining whether each of the VCs is equal to or greater than a predetermined value ε1.
@in pressure Each of VA, VB, and VC is connected to a line f between the other two phases, which is different from the negative phase voltage (for example, VA). 1 voltage (for example, VBC) for determining whether or not the phase is delayed by a predetermined angle C2 or more; In response to each output of the voltage determining means and the phase voltage line voltage phase difference determining means, the phase voltage of the corresponding phase is set to a predetermined value ε0.
In addition, when the phase voltage of the corresponding phase is delayed by a predetermined angle ε2 or more in phase, the configuration includes a calculation means for outputting a secondary circuit disconnection detection signal of the PT. In addition, three phases (A phase, B phase, C phase) are provided corresponding to each phase and input from the PT.
Phase voltage determination means for each phase for determining whether or not each of the phase voltages M, VB, and VC are equal to or higher than a predetermined value of 61, provided corresponding to each phase and adjacent to the phase (for example, human phase). line voltage (e.g. VAB,
A line voltage determining means for determining whether V is less than or equal to a predetermined value of 1, and each output of the phase voltage determining means and the line voltage determining means provided corresponding to each phase. and the phase voltage (for example, VA) of the corresponding phase is set to a predetermined value C.
The secondary circuit of the PT is disconnected when both of the image line filling pressures (for example, VAB, VC) between the corresponding phase and both adjacent phases are less than 1 to a predetermined value. The structure is equipped with an i-countable means for outputting a detection signal, and each of the three-phase line voltages VAB and V input and withdrawn from the PT.
nc, the line voltage provided corresponding to the VC person is set to a predetermined value! Determine whether it is smaller than =t='
J f2ft Calculation for receiving the outputs of the N pressure determining means and the line voltage determining means and outputting a secondary circuit disconnection detection signal of the PT when each of the line d pressures is less than a predetermined value of 8. It is equipped with means for three phases (A
Phase voltage determination means for each phase for determining whether or not each of the phase voltages Vmu, VB, and VC of the phases B, B, and C are equal to or higher than a predetermined value of 61; Phase voltage VA.

V, 3. The phase of each VC is determined whether the phase is delayed by a predetermined angle C2 or more from the line-to-line voltage (e.g., VBC) of a different voltage than the negative phase voltage (e.g., VA). flexural pressure line-to-line phase difference determining means, provided corresponding to each phase, and receiving outputs of the corresponding phase voltage determining means and phase voltage line-to-line pressure phase difference determining means; A first circuit that outputs a PT secondary circuit disconnection detection signal when the phase voltage of the corresponding phase is greater than or equal to a predetermined value c1 and the phase of the corresponding phase is delayed by a predetermined angle ε2 or more than the line voltage of the other two phases. A calculation means is provided corresponding to each phase, and the calculation means is provided corresponding to each phase.
A first line voltage determination that determines whether the line voltage (e.g., VAB, VC) between a phase (e.g., human phase) and an adjacent phase (e.g., B phase, C phase) is less than or equal to a predetermined value of 1. means, which are provided corresponding to each phase, and receive the respective outputs of the corresponding phase voltage discrimination means and the first line voltage discrimination means, so that the phase voltage (for example, VA) of the corresponding phase is smaller than a predetermined value ε. and the line voltage between the corresponding phase and both adjacent phases (e.g. VAB,
a second arithmetic means that outputs a secondary circuit disconnection detection signal of the PT when any of the voltages (Vc and Vc) is less than or equal to a predetermined value of 1;
'1' BCr A second line voltage determining means provided corresponding to the VC person and determining whether or not the corresponding line voltage is smaller than a predetermined value of 2; a line voltage determining means for the container 2; a third calculating means which receives the output of the means and outputs a secondary circuit disconnection detection signal of the PT when any of the line voltages is smaller than a predetermined value of 2; and the first to third calculating means. Since the configuration includes a fourth calculation means which receives each output and outputs a secondary circuit disconnection detection signal of the PT when at least one of the first to third calculation means outputs the output, it is different from the conventional one. There is no need to provide two sets of three-phase output circuits for the PT, and there is no need to provide a voltage balance relay to compare the output (voltage) of these two sets of output circuits. PT secondary circuit disconnection can be detected from the output of P.
Reliable P72 even when there is other line load in the T secondary circuit
This has the effect of making it possible to detect the next edge.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing a PT secondary circuit disconnection production circuit according to an embodiment of the present invention, FIG. 2 is a diagram showing a load connected to the PT secondary circuit, FIGS. 3, 4, and 5. The figure is PT2
Figures 6 and 7 are diagrams explaining the 1-phase r'rfr line of the next circuit, and Figures 81 and 81 are diagrams explaining the 2-phase disconnection.
A connection diagram showing the T secondary circuit, Figure 9 is the Wr of the PT secondary circuit.
FIG. 2 is a connection diagram showing a sequence for preventing malfunction of an output relay due to wires. In the figure, (3) is the PT, (5), (6), and (7) are the phase voltage detection means, and (81 (9) QOol) no. 3 is the first
QoI is the line voltage discrimination means, QoI is the phase voltage line difference phase difference discrimination means, (B) (To) (B) is the second line voltage discrimination means, and the copper spear (support) is the first calculation. means, (2) (c) 4 is the second calculating means, (to) is the third calculating means, (c) is the fourth calculating means, 81 to SA are the PT2 next line disconnection detection signal M* VB, V (is phase voltage, VAB r vBC
y VCA is line-to-line counter pressure. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (4)

[Claims] (1) Phase voltage determination means for each phase, which is provided corresponding to each phase and determines whether each of the three phase voltages V_A, V_B, and V_C input from the PT is equal to or greater than a predetermined value ε_1; The phase voltages V_A and V_B are provided corresponding to each phase.
, V_C is delayed by a predetermined angle ε_2 or more in phase from the line voltage between the other two phases (e.g. V_B_C) other than the phase voltage (e.g. V_A) of each phase. voltage line voltage phase difference discriminating means, and voltage line voltage phase difference discriminating means provided corresponding to each phase and receiving respective outputs of the corresponding phase voltage discriminating means and phase voltage line voltage phase difference discriminating means. Outputs the secondary circuit disconnection detection signal of the PT when the phase voltage is equal to or higher than the predetermined pressure value ε_1 and the phase voltage of the corresponding phase lags the line voltage between the other two phases by a predetermined angle ε_2 or more. Disconnection detection device for PT secondary circuit equipped with calculation means. (2) Phase voltages V_A, V_B of three phases (A phase, B phase, C phase) that are applied to each phase and input from the PT,
A phase voltage determination means for each phase that determines whether each of V_C is equal to or higher than a predetermined value ε_1, provided corresponding to each phase, and a means for determining the phase voltage of each phase (e.g., A phase) and adjacent phases (e.g., B phase, C line voltage determining means for determining whether the line voltage (for example, V_A_B, V_C_A) between the two phases (for example, V_A_B, V_C_A) is less than or equal to a predetermined value K_1, and the corresponding phase voltage determining means provided corresponding to each phase. and the phase voltage of the corresponding phase (for example, V_A) is smaller than the predetermined value ε_1, and the line voltage between the corresponding phase and both adjacent phases (for example, V_A_B , VC_A) are less than a predetermined value K_1, the PT secondary circuit disconnection detection device includes arithmetic means for outputting the PT secondary circuit disconnection detection signal. (3) Three-phase line voltage V_A_B input from PT
, V_B_C, V_C_A, and determines whether or not the corresponding line voltage is smaller than a predetermined value K_2; A disconnection detection device for a PT secondary circuit, comprising an arithmetic means for outputting a secondary circuit disconnection detection signal of the PT when both of the above are smaller than a predetermined value K_2. (4) Market pressures V_A, V_B of three phases (A phase, B phase, C phase) provided corresponding to each phase and input from PT,
Phase voltage determination means for each phase for determining whether or not each of V_C is equal to or greater than a predetermined value ε_1; For example, means for determining phase difference between phase voltages and line voltages of each phase for determining whether the phase is delayed by a predetermined angle ε_2 or more from the line voltage between other phases (for example, V_B_C) other than V_A); are provided in correspondence with each other, and receive the respective outputs of the corresponding phase voltage determining means and the phase voltage line voltage phase difference determining means to determine whether the phase voltage of the corresponding phase is equal to or greater than a predetermined value ε_1 and the corresponding phase a first calculation means for outputting a PT secondary circuit disconnection detection signal when the phase voltage of the phase lags the line voltage of the other two phases by a predetermined angle ε_2 or more; Line voltage between a phase (e.g. A phase) and an adjacent phase (e.g. B phase, C phase) (e.g. B phase,
Line voltage (e.g. V_A_B, V_C_
A) A first line voltage determining means for determining whether or not is less than or equal to a predetermined value K_1, each of the phase voltage determining means and the first line voltage determining means provided correspondingly to each phase. Upon receiving the output, the phase voltage (for example, V_A) of the corresponding phase is set to a predetermined value ε
Outputs the secondary circuit disconnection detection signal of the PT when it is smaller than _1 and both line voltages (for example, V_A_B, V_C_A) between the corresponding phase and both adjacent phases are less than or equal to a predetermined value K_1. a second calculation means to calculate the three-phase line voltages V_A_B, V_B_C, V_C input from the PT;
a second line voltage determining means provided corresponding to _A and determining whether or not the corresponding line voltage is smaller than a predetermined value K_2; third calculation means that outputs a secondary circuit disconnection detection signal of the PT when any of the line voltages is smaller than a predetermined value K_2;
~If at least one of the third calculation means outputs the PT
A disconnection detection device for a PT secondary circuit, comprising a fourth calculation means for outputting a secondary circuit disconnection detection signal.