JPH0429516A - Ratio differential relay unit - Google Patents

Abstract

PURPOSE:To detect abnormal input current due to malfunction of a metering current transformer per se, input current line disconnection or short circuit and also detect erroneous connection such as modification of system by displaying and continuously monitoring the input current characteristics of a ratio differential protective relay unit during operation of a transformer. CONSTITUTION:Input currents I1, I2 are converted, respectively, through an input isolation converter 9 and an A/D converter 10 into digital current value and phase angle which are then fed, as input data, to detecting elements from a system bus. Operation judging signals are read out from a differential current detecting element 11, a differential current ratio detecting element 12, an imbalance rate detecting element 13 and an input current phase difference detecting element 14, and when at least one of them is operating, duration of operation is counted to make a judgement whether the operation sustained longer than a predetermined time. If the operation sustained longer than a predetermined time, an abnormal input current alarm is outputted to the outside from an output interface section 18. Furthermore, detected data are stored in a memory table and displayed on a display processing element 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a ratio differential relay device used for detecting internal short-circuit accidents of transformers in power systems.

(Prior Art) Conventionally, a ratio differential protection relay device as shown in FIG. 9 has been used as a device for detecting an internal short-circuit accident of a transformer in a power system and protecting a circuit.

This ratio differential protection relay device is provided with an instrument current transformer 2 and a circuit breaker 3 on the primary side of a transformer 1.

An instrument current transformer 4 and a circuit breaker 5 are provided on the secondary side, and the current outputs of the instrument current transformers 2 and 4 on both sides are connected to a ratio differential relay 6. Currents I□ and I flowing through instrument current transformers 2 and 4 due to a short circuit accident, etc.
When the unbalance rate between 2 exceeds the set value, ratio differential relay 6
is activated and circuit breakers 3 and 5 are shut off to protect the circuit.

(Problem to be Solved by the Invention) However, in such a conventional ratio differential protection relay device, the primary and secondary transformation ratios of the transformer 1 and the instrument current transformer 2
．． The setting of the matching coefficient that corrects the input current ratio to the ratio differential relay 6 based on the current transformation ratio of 4, or the current transformer 2, 4
In order to prevent malfunctions due to connection errors or the like, it is necessary to test the input current characteristics of the ratio differential relay 6 under actual load operation.

In this input current characteristic test, as shown in Figure 10, measuring instruments 7 and 8 are connected to the current circuits of instrument current transformers 2 and 4, and the current value and phase of the current transformer □l L are measured and the ratio difference is measured. Moving relay 6
The operating characteristics of the ratio differential relay 6 are artificially compared and judged, and if there is an error in this characteristic test, it will not be possible to determine abnormalities in the input current and phase difference of the ratio differential relay 6 during normal operation, and the protection This results in the problem of not being able to operate.

The present invention was made in consideration of such conventional problems, and it is possible to directly display the input current status of a ratio differential relay without connecting an external measuring device, and to display the input current status of a ratio differential relay device. It is an object of the present invention to provide a ratio differential relay device that can quickly detect and issue an alarm that the state of the input current is abnormal with respect to the operating characteristics of the system.

[Structure of the invention]

(Means and effects for solving the problem) The present invention calculates a difference current ratio between primary and secondary input currents corrected by multiplying the input current by a preset matching coefficient, and this difference current ratio is set to a set value. A difference current ratio detection means that operates when the current difference exceeds a set value, and a difference current detection means that calculates the difference between the primary and secondary input currents corrected by multiplying by a matching coefficient, and operates when this difference current exceeds a set value. and an unbalance rate detection means that calculates the unbalance rate between the primary and secondary input current ratio and the set matching coefficient, and operates when this unbalance rate exceeds the set value, and This is a ratio differential relay device that is equipped with a phase difference detection means that calculates the phase difference between the input and When the magnitude of the difference current is greater than or equal to the set value for the corrected input current obtained by multiplying the current by the matching coefficient, and the difference current ratio of the corrected input current is also greater than or equal to the set value. In addition to applying the operating signal of the ratio differential relay device to 8, the unbalance rate between the input current ratio and the matching coefficient is calculated and this value is displayed, and the unbalance rate is above a certain value. When the input current is abnormal, it outputs an alarm. It also detects and displays the phase difference of the input current, and when this phase difference exceeds a certain value, it outputs an alarm as an input current abnormality. , and when differential current detection, differential current ratio detection, unbalance rate detection, and phase difference detection are performed, input current ratio, differential current value, and differential current ratio.

The unbalance factor between the input current and the matching coefficient and the detected value of the input current phase are stored and displayed.

(Example) An embodiment of the present invention is shown in FIG.

In FIG. 1, input currents I, , I, are converted into digital quantities of current value Idz y Idz and phase angle φ1 . The converted current value Ia is converted into φ2.
Idz and phase angle φ8. φ2 is sent as input data to each detection element via the system bus.

In the differential current detection element 11, the current value Idz and phase angle data φ1 corresponding to the input current 2, the current value data Id2 and the phase angle data φ2 corresponding to the input current 2, and further set in the preset data element 15. At the same time, take out the matching coefficient and the differential current operation value SET△ from the system bus, calculate the differential current value △■ according to the following formula, for example,
The two are compared to determine an abnormality.

ΔI =? (Ia, 4)2+ (Idz)2-:l
' (I City・K4a, ・Co5(φ2−φ,)−π)
Abnormal when ∆I≧SET∆engineering.

An example of a vector diagram of the differential current ΔI is shown in FIG.

The difference current ratio detection element 12 converts the above conversion data Id +
Idz+φ0. φ2, and preset data element 1
Difference current ratio operating value set to 5 SET△work (%)
is taken out from the system bus, and the difference current ratio Δwork (%) is calculated according to the following formula, for example, and the two are compared to determine an abnormality.

Abnormal when Δ■ (%) ≧ SET△ engineering (%).

Furthermore, the unbalance rate ERR (%) detection element 13 uses the conversion data Id□, Ia2 and the input setting data element 1 in advance.
5 Matching coefficient set and unbalance rate operating value 5ETE
The ER (%) is taken out from the system bus, and the unbalance rate ERR (%) is calculated according to the following formula, for example, and the two are compared to determine an abnormality.

Abnormal when ERR%≧5ETERR(%).

In addition, the input current phase difference detection element 14 uses the converted data φ4. φ2 and the phase difference abnormality operation value SETφ set in advance in the setting data element 15 are taken out from the system bus, and the phase difference φ is calculated according to the following formula, for example, and the two are compared to determine the phase difference abnormality.

Phase difference φ=1φ2−φ1 Phase difference abnormality determination 1: Abnormal when φ-π1≧SETφ.

The input current ItI2 during normal operation is a reverse polarity current (π: 180
degree phase difference), as shown in the vector diagram of FIG.

The phase difference φ detected in the vector diagram of FIG.

φ=φ2-φ1=180° (=π) Therefore, the phase difference abnormality determination becomes φ−π=0.

φ−π1≧SETφ is not established and an abnormality is not determined.

Figures 4 and 5 show an example where the input current phase is different due to a connection error in the secondary of a current transformer, or the current polarity of the CT secondary is different. For example, the phase difference abnormal operation value SETφ is set to 5''.

FIG. 4 is a vector diagram when the T-phase current is input to the workpiece 2 where the R-phase current should be input, and the phase difference φ=φ2−
φ□=240° Phase difference abnormality judgment is 1φ−π1≧SETφ$ −tc
11240'-180"1=60">SE
Tφ:5', and a phase difference abnormality is detected.

Figure 5 is a vector diagram when the CT secondary current polarity is different although the input is in the same mode, and the phase difference φ = φ2 - φ,
=0 For phase difference abnormality determination, 1φ−π1≧SETφφ−π1=1
0° −180′ 1=1806 >SETφ:5°, and a phase difference abnormality is detected.

Further, in the output processing element 17, the difference current horizontal element 11.degree., the difference current ratio detection element 12. Each operation signal detected by the processing of the unbalance rate detection element 13 and the input current phase difference detection element 14 is read and outputted via the output interface 18, and output processing of the operation signal of the ratio differential relay device is performed. Execute at regular intervals.

That is, for example, as shown in the flowchart of FIG.
First, a process S1 for reading the differential current operation determination signal from the differential current detection element 11 and the differential current ratio operation determination signal from the differential current ratio detection element 12 is executed.

Next, as a result of the reading process S1, a process S2 for determining whether or not the differential current motion determination signal and the differential current ratio operation determination signal are both operating is executed, and if they are operating, the ratio differential relay The operation signal output processing S3 is executed and outputted to the outside via the output interface 18, and if not, the operation output processing is ended.

Furthermore, after execution of the operation output processing, the above-mentioned difference current detection element 1
1. difference current ratio detection element 12, imbalance rate detection element 13,
and each datum work, Δwork%, ERR%, and φ from the input current phase difference detection element 14 are stored in the memory table, and display processing S4 is executed via the display processing element 16, and the operation output processing is ended. do.

The output processing element 17 also executes an input current abnormality detection process as shown in FIG. 7, for example, at regular intervals.

That is, first, the above-mentioned difference current detection element 11, difference current ratio detection element 12. A process Sll for reading each operation determination signal from the unbalance rate detection element 13 and the input current phase difference detection element 14 is executed.

Next, each operation determination signal read in the read processing Sll, that is, a difference current operation determination signal, a difference current ratio operation determination signal,
Executing a process S12 for determining whether either the unbalance rate operation determination signal or the phase difference operation determination signal is operating;
If none of the above operation judgment signals are operating, the input current abnormality detection process is terminated, and if at least one of the above operation judgment signals is operating, operation continuation time counting processing S13 is executed. Next, a determination process 514 is executed to determine whether the process has continued for a predetermined time or more.

If it is determined in the predetermined time continuation determination process 14 that the process has not continued for a predetermined time or longer, the process is terminated, and if it is determined that the process has continued for a predetermined time or more, an input current abnormality alarm signal output process S15 is executed and output. An input current abnormality alarm is output to the outside via the interface 18.

Furthermore, the difference current detection element 11 and the difference current ratio detection element 1
2. Each detection data ΔI, Δwork%, ERR%, from the unbalance rate detection element 13 and the input current phase difference detection element 14,
and φ in the storage table, and display processing element 16
The stored data display process S16 is executed via the input current abnormality detection process, thereby terminating the input current abnormality detection process.

Furthermore, by inputting a data display request signal to the setting element 15 shown in FIG. 1, it is also possible to display the detected data △I, ∆work%, ERR%, and φ according to the input current situation at any time. It is possible.

Furthermore, detection of harmonic components contained in the input current, filter processing, etc. can be added in the same manner as in the past.

Next, the operation of the ratio differential relay device having the above configuration will be explained.

As shown in FIG. 8, this ratio differential relay device 19 includes a voltage transformer 2 and a circuit breaker 3 on the primary side of a transformer 1, and a voltage transformer 4 and a circuit breaker on the secondary side. The current transformers 2 and 4 are connected so that the output currents of the current transformers 2 and 4 become input currents I and I2 having a phase difference of 180''.

By using the above configuration, if an excessive current flows due to an internal short circuit accident in the transformer 1, a large unbalance will occur between the current transformers 2 and 4, and this imbalance will occur. Ratio differential relay device 1 by balanced current input
9 operates and outputs a trip signal to circuit breakers 2 and 5.

In this case, under normal conditions, the input currents and 2 are in opposite phase, and after being converted to Id - Idz by the analog/digital converter I#10, Id is corrected by the matching coefficient. Idz・K=Id2 and the difference current value △
As mentioned above, the distance is calculated using the following formula.

△I = J (Ich ・K)” + (Id= )2
- :' (Ia, ・Ni4 cities・Co5(φ2−φ,)
−, ) where φ2−φ, = 180” (7c), I
dx 'K = Idz, and Idx ・K =
If Idz = a, ΔI = Ja"10a" -2
a''Co5(180'-π)=0, and the difference current ratio also becomes ΔWork%=O.

Moreover, the unbalance rate ERR% is also because Id□·K=Id.

Furthermore, the input current phase difference φ is φ=φ2−φ□180°
In the phase difference abnormality determination, 1φ−π1=0″.

As mentioned above, if the connection between the primary sides of the instrument current transformers 2 and 4 is normal, and the input current ratio based on the transformation ratio of the transformer 1 and the current transformation ratio of the instrument current transformers 2 and 4 is equal to the matching coefficient K. If properly corrected by , all of △I, △work%, ERR%, and φ will be inoperative.

- If there is a connection error in the current transformer for a force meter, and the input current has the opposite phase polarity or a current of another phase is taken in, the phase difference and the input A difference current Δwork corresponding to the magnitude of the current and a difference current ratio Δwork % corresponding to the phase difference are detected, and furthermore, a phase difference abnormal angle of the phase difference is detected.

In addition, when the matching coefficient K is not set to an appropriate value, the difference current Δ%, the difference current ratio Δ■%, and the unbalance rate ERR
% is detected. Therefore, by setting the unbalance rate ERR% detection set value 5ETERR (%) and the phase difference abnormality detection set value SETφ as small as possible, if the system is operating with a relatively light load, ratio differential relaying can be applied. Abnormal conditions caused by the above-mentioned errors can be discovered before the device malfunctions, and the characteristics of the ratio differential relay device itself can be easily tested.

〔Effect of the invention〕

As explained above, the ratio differential relay device according to the present invention has
Since the present invention includes means for detecting a difference current and a difference current ratio with respect to the input current and a display means thereof, a means for detecting an unbalance rate of the input current ratio and a matching coefficient and a display means therefor, and a means for detecting a phase difference and a display means therefor, There is no need to connect a separate measuring device for characteristic testing, and the input current characteristics of the ratio differential protection relay device can be constantly monitored through the display on the display means while the transformer is operating. It is now possible to detect abnormalities in the current input due to a defect in itself or due to disconnection or short circuit of the input current line, and even if a wiring error occurs due to system modification or change, the abnormal state can be easily detected. It becomes possible.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of a ratio differential relay device according to the present invention, FIGS. 2 to 5 are vector diagrams for explaining the present invention in detail, and FIGS. 6 and 7 respectively. 8 is a flowchart showing the operation process of the present invention, FIG. 8 is a system diagram when the present invention is used as a protective relay device for a transformer, and FIGS. FIG. 2 is a system diagram and a test circuit diagram when used to protect equipment. 1... Transformer 2, 4... Instrument current transformer 3.5... Circuit breaker 6... Ratio differential relay 7
．． 8. = Measuring instrument 9... Input isolation converter 10.
...Analog/digital converter 11...Difference current detection element 12...Difference current ratio detection element 1:L-1 unbalance rate detection element 14...Phase difference detection element 15...Setting processing element 16 ...Display processing element 17...Output processing element 18...Output interface 19...Ratio differential relay device (8733) Agent Patent attorney Yoshiaki Inomata (and 1 others)
Name) Figure Figure Figure Number Flash (Hiki difference Gaiden certain 1pukun 4T water Norotsu Figure figure (person-0'tj contract busy branch 70-) Figure Figure Figure

Claims (1)

[Claims] A difference current ratio detection means that calculates a difference current ratio between the corrected primary and secondary currents by multiplying by a preset matching coefficient, and operates when this difference current ratio exceeds a set value; The difference between the primary and secondary currents is determined, and the unbalance rate between the primary and secondary current ratio and the matching coefficient is determined. unbalance rate detection means that operates when the balance rate exceeds a set value; phase detection means that determines the phase difference between the primary and secondary currents and operates when this phase difference exceeds the set value; and each of the above. A ratio differential relay device characterized by comprising display means for displaying a detected value.