JPH11308755A - Ratio differential relay device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a non-inrush detection means from outputting a non-locking signal unnecessarily and a DT becoming saturated with a DC component in an inrush current and a second harmonic component decreasing. SOLUTION: This device is provided with a suppression current-leading equipment 11 for leading a suppression current from each terminal current of a device to be protected, differential current-leading equipment 12 for leading differential current from each terminal current, a ratio differentiator 13 for making on output when the suppression current and the differential current are in a specified relationship, an non-inrush detection means 20 that extracts the fundamental wave component and the second harmonic component in the differential current to be output, when the ratio of the fundamental wave component to the second harmonic component is equal to or less than a specified value, a logical product circuit 17 for outputting a signal for breaking the device to be protected from the system, when there is output from a DC content detection means for outputting when the DC content in the differential current is equal to or more than a specified value, a radio differential means, and a non-inrush detection means 20. The non-inrush detection means 20 is controlled by the output of the DC content detection means, and the non-inrush detection means 20 on inrush is prevented from making output at non-inpush time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ratio differential relay for protecting a transformer in a power system, and particularly to a highly reliable relay that does not operate unnecessarily even when CT is saturated by a DC component in an inrush current. The present invention relates to a ratio differential relay device.

[0002]

2. Description of the Related Art FIG. 17 is a diagram showing a power system to which a conventional ratio differential relay device is applied. In the figure, reference numeral 1 denotes a protected transformer and 2 denotes a primary side of a transformer 1. Circuit breaker,
3 is a circuit breaker installed on the secondary side of the transformer 1, 4 is a current transformer (hereinafter referred to as CT) for measuring the primary current 11 (high-side current) of the transformer 1, and 5 is a transformer of the transformer 1 Secondary current I2
A current transformer (hereinafter referred to as CT) for measuring (low-voltage side current) 6 is a circuit breaker 2 when a failure occurs within the protection range.
And a differential relay device that trips the circuit breaker 3 to disconnect the transformer 1 from the power system.

FIG. 18 shows, for example, Japanese Patent Application Laid-Open No. 53-111451.
FIG. 17 is a configuration diagram showing a conventional ratio differential relay device described in Japanese Patent Application Laid-Open Publication No. H10-207, in which I1 is a primary current I1 measured from CT4 in FIG. 17 and a secondary current I measured from CT5.
2, a suppression current deriving device for deriving a current having a larger current value as the suppression current Ir, 12 is an operating current deriving device for the primary current I1 and the secondary current I2, and 13 is a differential current Id for the suppression current Ir. Is a ratio differential device that outputs a trip signal when the ratio is equal to or greater than a predetermined value. Reference numeral 20 denotes a non-inrush detecting means for outputting a non-lock signal when it is determined that the power system is not in an inrush state.
Is a logical product circuit that outputs a trip signal of the circuit breaker and disconnects the transformer 1 from the power system when a non-lock signal is output from the non-inrush detection means 20 while a trip signal is output from the non-inrush detection means 20.

In the non-inrush detecting means 20, 1
4 is a differential current Id derived by the differential current deriving device 12
, A second harmonic filter 15 for extracting a second harmonic component Id2 included in the differential current Id derived by the differential current deriving unit 12, Reference numeral 16 denotes a second harmonic component Id with respect to the fundamental component Id0 when the differential current Id is equal to or greater than a predetermined value.
An inrush determiner that determines that the power system is not in an inrush state when the ratio of 2 is equal to or less than a predetermined value and outputs a non-lock signal.

Next, the operation will be described. Ratio differential relay 6
As shown in FIG. 17, the general function of the transformer 1 is that the transformer 1 is not disconnected from the power system even when the external fault FO occurs in the power system, but when the internal fault FI occurs in the power system, In order to protect the transformer 1, the transformer 1 is disconnected from the power system. Specifically, first, the suppression current deriving unit 11 determines that the primary current I1 measured by CT4 and CT
The secondary current I2 measured in step 5 is compared, and the current having the larger current value is derived as the suppression current Ir. Further, the differential current deriving unit 12 derives a vector difference between the primary current I1 measured by CT4 and the secondary current I2 measured by CT5 as a differential current Id. In addition, the ratio differential device 13 generally provides the differential current Id with respect to the suppression current Ir.
Is greater than or equal to a predetermined value, it is highly probable that an internal failure FI has occurred in the power system. Therefore, when the following condition is satisfied, a trip signal is output. Id> KF1 × Ir + KM where KF1 and KM are predetermined constants

On the other hand, filters 14 and 15
Is the differential current Id derived by the differential current
To extract the fundamental wave component Id0 and the second harmonic wave component Id2 included in. Then, the inrush determiner 16 determines whether or not the power system is in an inrush state based on the two components. The installation of the non-inrush detecting means 20 including the inrush determining unit 16 is performed when the power system is in an inrush state (generally, when the circuit breaker 3 is in the open state and the circuit breaker 2 is changed from the open state to the closed state). Inrush current occurs when the transformer 1
The ratio differential 13 may output a trip signal due to a phenomenon similar to the case where the internal failure FI occurs in the power system. This is because it is not necessary to prevent the transformer 1 from being disconnected from the power system.

That is, the non-inrush detecting means 20 outputs the non-lock signal only when the power system is not in the inrush state, and makes the trip signal output by the ratio differential unit 13 effective. When the current Id is equal to or more than a predetermined value and the ratio of the second harmonic component Id2 to the fundamental wave component Id0 is equal to or less than a predetermined value shown in the following equation, it is determined that the power system is not in an inrush state, and a non-lock signal is output. I do. Id2 <KF2 × Id0, where KF2 is a predetermined constant where the second harmonic component Id with respect to the fundamental component Id0
The ratio of 2 is used for the determination because the inrush current is
This is because the second harmonic current component Id2 is included more than the fault current. The AND circuit 17 includes the ratio differential unit 13
When the trip signal is output from the controller and the non-lock signal is output from the non-inrush detecting means 20, it is determined that the internal fault FI has occurred in the power system, and the transformer 1 is disconnected from the power system. A series of operations ends.

Next, the operation for the inrush current will be described with reference to the waveform diagrams of FIGS. Note that FIG.
FIG. 20A shows the primary current of CT4 when an inrush occurs, and FIG. 20B shows the secondary current of CT4 when an inrush occurs. In FIG. 19, the ratio differential 13 is
When the differential current Id is equal to or greater than the above-described predetermined value, the time t _OP13 (for example, 4 cycles on a 50-Hz
0 ms) (c), but the inrush current does contain a large amount of the second harmonic component Id2, so that the inrush determiner 16 does not output (d). Therefore, the AND circuit 17
Is not output (e).

Next, the operation when the CT is saturated by the inrush current will be described with reference to the waveform diagram of FIG. The ratio differentiator 13 detects the time t _OP as in the case where there is no CT saturation.
The output is performed after 13 (c). Up to the third wave of the inrush current, there is no CT saturation and a typical inrush current waveform in a so-called half-wave shape. However, since the DC component in the inrush current is integrated from the fourth wave, the CT core becomes Saturation (b) causes the waveform of the CT secondary current to fluctuate slightly in the positive and negative directions. The harmonic analysis shows that the third harmonic increases and the ratio of the second harmonic component decreases. Therefore, the inrush determiner 16 determines the time t _OP from the rising point of the fourth wave.
Sixteen hours later, the unlock signal is erroneously output in spite of the inrush time (d), and the AND circuit 17 outputs unnecessary (e), and the transformer 1 is cut off from the power system.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has a high degree of reliability in that a non-lock signal is not output unnecessarily even when CT is saturated by an inrush current. The purpose is to obtain a ratio differential relay.

[0011]

SUMMARY OF THE INVENTION A ratio differential relay according to the present invention comprises suppression current deriving means for deriving a suppression current from each terminal current of a device to be protected, and a differential current from each terminal current. A differential current deriving unit, a ratio differential unit that outputs when the suppression current and the differential current have a predetermined relation, a fundamental wave component and a second harmonic component in the differential current, and a second harmonic with respect to the fundamental wave component Non-inrush detection means for outputting when the ratio of wave components is equal to or less than a predetermined value, DC component detection means for outputting when the DC component in the differential current is equal to or more than a predetermined value, and the ratio differential means and non-inrush detection means And an AND circuit that outputs a signal for shutting off the protected device from the system when both outputs are present, and controls the non-inrush detection means by the output of the DC component detection means. Or In which was not allowed to issue the output.

The DC component detecting means includes a DC component deriving means for deriving a DC component in the differential current, a DC component deriving means for integrating the output of the DC component deriving means, and outputting when the integrated amount is equal to or more than a predetermined value. And integrating means.

The DC component detecting means includes: a DC component deriving device for deriving a DC component in the differential current; a DC component level detecting device for outputting when the magnitude of the DC component is equal to or greater than a predetermined value; Timer means for outputting when the output of the detecting means continues for a predetermined time.

The DC component detecting means includes a DC component deriving means for deriving a DC component in the differential current, and a DC component output when the magnitude ratio of the DC component to the fundamental wave in the differential current is a predetermined value or more. And a timer means for outputting when the output of the DC content rate detecting means has continued for a predetermined time.

Further, a suppression current deriving means for deriving a suppression current from each terminal current of the protected device, a differential current deriving means for deriving a differential current from each of the terminal currents, and a predetermined relation between the suppression current and the differential current. A differential output means for extracting the fundamental wave component and the second harmonic component in the differential current, and outputting when the ratio of the second harmonic component to the fundamental wave component is less than a predetermined value. Means, a second harmonic detecting means for outputting in accordance with a ratio between a fundamental wave component and a second harmonic component in the differential current, and when there is output from both the ratio differential means and the non-inrush detecting means, An AND circuit for outputting a signal for shutting off the protected device from the system is provided, and the non-inrush detecting means is controlled by the output of the second harmonic detecting means. To Those were.

The second harmonic detecting means includes a second harmonic content detecting means for outputting when a ratio of the second harmonic to a fundamental wave in the differential current is equal to or greater than a predetermined value. Timer means for outputting when the output of the harmonic content detection means has continued for a predetermined time.

Further, the second harmonic detecting means includes second harmonic decrease detecting means for outputting when the ratio of the second harmonic to the fundamental in the differential current tends to decrease by a predetermined value or more. Things.

Further, a suppression current deriving means for deriving a suppression current from each terminal current of the device to be protected, a differential current deriving means for deriving a differential current from each terminal current, and wherein the suppression current and the differential current have a predetermined relationship. Differential output means, a non-inrush detecting means for outputting when the ratio of the second harmonic component to the fundamental component in the differential current is equal to or less than a predetermined value, and each phase current of the high voltage side terminal or the low voltage side terminal And a DC component detecting means for outputting in accordance with the added value of the zero-phase current, and an AND circuit for outputting a signal for shutting off the protected device from the system when there is an output from both the ratio differential means and the non-inrush detecting means. The non-inrush detecting means is controlled by the output of the DC component detecting means so that no output is output from the non-inrush detecting means at the time of inrush.

The DC component detecting means includes means for adding each phase current and the zero-phase current of the high voltage side terminal, and output level detecting means for outputting when the output of the adding means is equal to or more than a predetermined value.
Means for adding each phase current and the zero-phase current of the low voltage side terminal, output level detecting means for outputting when the output of the adding means is equal to or more than a predetermined value, and logic for outputting the logical sum of the outputs of the two output level detecting means And a sum circuit.

The DC component detecting means includes means for adding each phase current and the zero-phase current of the high voltage side terminal, and a DC signal output when the ratio of the DC component to the fundamental wave in the output of the adding means is equal to or more than a predetermined value. Means for detecting share ratio, means for adding each phase current and zero-phase current of the low-voltage side terminal, and the DC component content output when the ratio of the DC component to the fundamental wave in the output of the adder is equal to or greater than a predetermined value. A detecting means, and a logical sum means for outputting a logical sum of outputs of the two direct current component content rate detecting means.

Further, a suppression current deriving means for deriving a suppression current from each terminal current of the protected device, a differential current deriving means for deriving a differential current from each of the terminal currents, a predetermined relationship between the suppression current and the differential current. A differential output means for extracting the fundamental wave component and the second harmonic component in the differential current, and outputting when the ratio of the second harmonic component to the fundamental wave component is less than a predetermined value. Means, DC component deriving means for deriving a DC component in the differential current, DC component integrating means for integrating the output of the DC component deriving means and outputting when the amount of integration is equal to or more than a certain value, once from the DC component integrating means. A one-shot timer that outputs a pulse of a predetermined time width when there is an output, an AND circuit that outputs a signal for shutting off the protected device from the system when there is an output from both the ratio differential means and the non-inrush detection means, and Wa The output of Shototaima those having the inhibit circuit for locking the output of the AND circuit.

The DC component detecting means includes a DC component deriving means for deriving a DC component in the differential current and an output of the DC component deriving means, and outputs when the integrated amount is equal to or more than a first predetermined value. And a second DC component integrating means for integrating the output of the DC component deriving means and outputting when the integrated amount is equal to or greater than a second predetermined value.

Further, a suppression current deriving means for deriving a suppression current from each terminal current of the protected device, a differential current deriving means for deriving a differential current from each of the terminal currents, and wherein the suppression current and the differential current are predetermined. Ratio differential means for outputting when the relation is present, non-inrush detecting means for outputting when the ratio of the second harmonic current to the fundamental wave current in the differential current is equal to or less than a predetermined value, and direct current component in the high-side terminal current DC component deriving means, DC component integrating means for integrating the output of the DC component deriving means, and outputting when the integration amount is equal to or more than a predetermined value, DC component deriving means for deriving a DC component in the low-voltage side terminal current, DC integration means for integrating the output of the integration deriving means and outputting when the amount of integration is equal to or greater than a predetermined value, an OR circuit for outputting the logical sum of the outputs of the DC integration means, and Inrush detection means When there is an output, a logical product circuit that outputs a signal for shutting off the protected device from the system is provided, and the non-inrush detecting means is controlled by the output of the logical sum circuit. The output is not output.

Further, the non-inrush detecting means includes a fundamental filter for extracting a fundamental component in the differential current, a second harmonic filter for extracting a second harmonic component, and a second harmonic filter for the fundamental component. A variable ratio inrush determiner capable of controlling the ratio sensitivity of the second harmonic by an external signal while determining the ratio of the harmonic components.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing a ratio differential relay device according to Embodiment 1 of the present invention. In the drawing, reference numeral 100 denotes a second harmonic component Id.
A variable ratio inrush determiner capable of controlling the ratio sensitivity of 2; 101, a DC component deriving device for deriving a DC component in the differential current Id; 102, an output of the DC component deriving device 101 which is integrated; This is a DC component integrating means that outputs when the value exceeds the value. Other configurations are the same as those shown in FIG.

Next, the operation will be described with reference to the waveform diagram of FIG. (A) of the figure shows the primary side current of CT4 at the time of inrush occurrence, and (b) shows the secondary side current of CT4 at the time of inrush occurrence. The DC component in the output differential current Id of the differential current deriving device 12 to which the inrush current is applied is derived by the DC component deriving device 101 (f), and the DC component deriving device 10
One output Idd is integrated by the DC component integrating means 102. When the integral reaches a predetermined value and the time t _OP 102 after the inrush current is applied, the DC component integrating means 102 outputs (g), and the second ratio of the variable ratio inrush determiner 100
The harmonic ratio sensitivity is changed from, for example, 12% to 8%.
Due to the reduction of the sensitivity, the inrush determiner 100 does not output the non-lock signal even if the CT is saturated by the inrush current and the second harmonic content in the differential current Id decreases (b). ). For this reason, the signal which shuts down the transformer unnecessarily at the time of inrush from the AND means 17 is not output.

Embodiment 2 FIG. FIG. 3 is a block diagram showing a ratio differential relay device according to Embodiment 2 of the present invention. In the figure, reference numeral 103 denotes a DC component level detecting means that outputs when the magnitude of the DC component Idd is equal to or larger than a predetermined value. And 104 are timers that output when the output of the DC level detecting means 103 has continued for a predetermined time or more. Other configurations are the same as those in FIG.

Next, the operation will be described. The DC component in the output differential current Id of the differential current deriving device 12 to which the inrush current is applied is derived by the DC component deriving device 101, and the magnitude of the output Idd of the DC component deriving device 101 is a predetermined value (for example, rated If it is 10% of the current or more, the DC component level detector 103 outputs and the timer 104 is activated. When the timer 104 counts up after a predetermined time (for example, after T1 = 1 second), the second harmonic ratio sensitivity of the variable ratio inrush determiner 100 is changed from 12% to 8%, for example. Due to this reduction in sensitivity, even if CT4 is saturated by the inrush current and the second harmonic content in the differential current Id decreases, the inrush determiner 100 does not output the unlock signal. Therefore, a signal for unnecessarily shutting down the transformer 1 is not output from the logical product means 17 at the time of inrush.

Embodiment 3 FIG. 4 is a block diagram showing a ratio differential relay device according to Embodiment 3 of the present invention. In the figure, reference numeral 105 denotes a ratio of a DC component Idd to a fundamental wave in a differential current Id which is a predetermined value (for example, 40%) or more, a DC component detecting means 106 that outputs when the output is equal to or more than 40% is a timer that outputs when the output of the DC component detecting means 105 continues for a predetermined time.

Next, the operation will be described with reference to the waveform diagram of FIG. Differential current deriving device 12 to which inrush current is applied
The DC component in the output differential current Id is derived by the DC component deriving device 101 (f), and the magnitude of the DC component Idd is greater than or equal to a predetermined ratio compared to the fundamental wave component output Id0 of the fundamental filter 14. If there is, the DC component content detection means 105 outputs the signal after the detection time t _OP 105 (g), and the timer 106 is activated. After a predetermined time (for example, T2 = 1 second), the timer 106
Is counted up (h), the second harmonic ratio sensitivity of the variable ratio inrush determiner 100 is changed from, for example, 12% to 8%. Due to this reduction in sensitivity, even if CT4 is saturated by the inrush current and the second harmonic content in the differential current Id decreases, the inrush determiner 100 does not output (e). Therefore, a signal for unnecessarily shutting down the transformer 1 is not output from the logical product means 17 at the time of inrush.

Embodiment 4 FIG. FIG. 6 is a block diagram showing a ratio differential relay device according to Embodiment 4 of the present invention. In the drawing, reference numeral 107 denotes a ratio of the second harmonic component current Id2 to the fundamental current Id0 in the differential current Id. The second harmonic content detection means 108 that outputs when the ratio is equal to or more than a predetermined ratio (for example, 12%), and the second harmonic content detection means 107
Is a timer that is output when the output of continues for a predetermined time.

Next, the operation will be described with reference to the waveform diagram of FIG. Differential current deriving device 12 to which inrush current is applied
Of the second harmonic component current Id2 in the output differential current Id of
The second harmonic component current Id derived by the harmonic filter 15
2 is the fundamental current Id0 of the fundamental filter 14
If the ratio is equal to or larger than the predetermined ratio, the second harmonic content detection means 107 outputs the signal after the detection time t _OP 107 (f), and the timer 108 is activated. When the timer 108 counts up after a predetermined time (for example, after T3 = 1 second) (g), the second harmonic ratio sensitivity of the variable ratio inrush determiner 100 is changed from 12% to 8%, for example. Due to this reduction in sensitivity, the inrush current does not output (e) even if CT4 is saturated by the inrush current and (b) the second harmonic content in the differential current Id decreases. Therefore, a signal for unnecessarily shutting down the transformer 1 is not output from the AND circuit 17 at the time of inrush.

Embodiment 5 FIG. FIG. 8 is a block diagram showing a ratio differential relay device according to Embodiment 5 of the present invention. In the drawing, reference numeral 109 denotes a ratio of the second harmonic component current Id2 to the fundamental current Id0 in the differential current Id. Second harmonic decrease detection means for outputting when the ratio is decreasing more than a predetermined ratio (for example, -2% / cycle). Other configurations are the same as those in FIG.

In general, the content of the second harmonic in the inrush current generally increases slightly with the passage of time. In the fifth embodiment, however, the second harmonic current decreases at the onset of CT saturation. This is to change the sensitivity of the variable inrush determiner 100 by grasping the tendency. Next, the operation will be described with reference to the waveform diagram of FIG. The second harmonic component current Id2 of the output differential current Id of the differential current deriving device 12 to which the inrush current is applied is derived from the second harmonic filter 15, and has a magnitude of the second harmonic component current Id2. If the ratio of the fundamental wave filter 14 to the magnitude of the fundamental wave current Id0 tends to decrease by a predetermined ratio or more, the second harmonic decrease detecting means 1
09 is output after the detection time t _OP 109 (f), and the second harmonic ratio sensitivity of the variable ratio inrush determiner 100 is changed, for example, from 12% to 8%. Due to the reduction in sensitivity, even if CT4 is saturated by the inrush current and the second harmonic content in the differential current Id decreases, the inrush determiner 100 does not output the unlock signal (e). Therefore, a signal for unnecessarily shutting down the transformer 1 is not output from the AND circuit 17 at the time of inrush.

Embodiment 6 FIG. FIG. 10 is a block diagram showing a ratio differential relay device according to Embodiment 6 of the present invention. In the figure, reference numeral 110 denotes a high-side phase current I1A, a phase current I1B, a phase current I1C, and a zero-phase current I1N. Is a first level detecting means for outputting when the output of the first adding means 110 is equal to or larger than a predetermined value, and 111 is a low-voltage-side phase current I2A and a phase current I2.
B, the second of adding the phase current I2C and the zero-phase current I2N
Is a second level detecting means for outputting when the output of the second adding means 111 is equal to or larger than a predetermined value, and 114 is a logical sum means.

Next, the operation will be described. First adding means 11
0, the output of the second adder 111 is zero if there is no saturation of each CT, in any of the normal, external, internal, and in-rush situations, but at least the A-phase, B-phase, and C-phase.
If any CT saturates, it will not be zero. For example, when an inrush current including a large DC component is applied from the high voltage side, the first adder circuit 1
The first level detection means 112 outputs when the output is greater than or equal to a predetermined value.
, The second harmonic ratio sensitivity of the variable ratio inrush determiner 100 is changed from, for example, 12% to 8%. Due to the reduction in sensitivity, even if CT4 is saturated by the inrush current and the second harmonic content in the high-voltage side current I1 is reduced, the inrush determiner 100 does not output the unlock signal. Therefore, the AND circuit 17 does not output unnecessarily. The same operation is performed on the low pressure side.

FIG. 16 shows a power system diagram in which the application of this embodiment is effective. In FIG. 16, 201 is a bus, 203 is a transformer, and 202 is a circuit breaker. FIG.
When the transformer 1 is operating (the circuit breakers 2 and 3 are both closed) in the system of the above, when the circuit breaker 202 is closed, the inrush current passes through CT4 and CT5 and the ratio differential relay 6
No differential current is generated in the differential circuit (there is no output of the differential current deriving unit 12). However, according to the sixth embodiment, not the differential current as described above but the high-voltage side or the low-voltage side Since a method of detecting the saturation of CT due to the inrush current from the current is employed, malfunction can be prevented even when applied to such a system.

Embodiment 7 FIG. 11 is a block diagram showing a ratio differential relay device according to Embodiment 7 of the present invention. In the drawing, reference numeral 115 denotes a predetermined ratio of the DC component to the fundamental wave output from the first adding means 110. The first DC sharing ratio detecting means 116 that outputs when the ratio is equal to or more than the value is a second DC sharing ratio that outputs when the ratio of the DC component to the fundamental wave output from the second adding unit 111 is equal to or more than a predetermined value. The percentage detection means 117 is a logical sum means. Other configurations are shown in FIG.
Is the same as

Next, the operation will be described. First adding means 11
0, the output of the second adding means 111 is zero when there is no saturation of each CT, at the time of soundness, at the time of external failure, at the time of internal failure, and at the time of inrush, but at least A phase, B phase, C phase,
If any CT is saturated, it will not be zero. For example, when an inrush current including a large amount of DC component is applied from the high voltage side, the first adding means 110
If the output includes a DC component equal to or more than a predetermined ratio, the first DC sharing ratio detection means 115 outputs the output, passes through the logical sum means 117, and outputs the variable ratio inrush judgment signal. 100 detection sensitivity, for example 12% to 8%
Change to

Due to the reduction in sensitivity, even if CT is saturated by the inrush current and the second harmonic content in the high-voltage side current I1 is reduced, the inrush determiner 100 does not output the unlock signal. Therefore, the AND circuit 17 does not output unnecessarily at the time of inrush. According to the seventh embodiment, as described above, the method of detecting the saturation of the CT due to the inrush current from the high voltage side or the low voltage side current instead of the differential current is used. This is particularly effective when applied to a system as shown in FIG.

Embodiment 8 FIG. FIG. 12 is a block diagram showing a ratio differential relay device according to Embodiment 8 of the present invention. In the drawing, reference numeral 118 denotes a pulse having a predetermined time width when there is an output from the DC component integrating means 102 once. This is a one-shot timer. Here, the one-shot timer 118
The pulse time width of CT is calculated by the DC component of the inrush current.
Is set, for example, to 1 second in consideration of the saturation continuation time. 11
9 is an inhibit circuit.

Next, the operation will be described. The DC component in the output differential current Id of the differential current deriving device 12 to which the inrush current is applied is derived by the DC component deriving device 101, and the output current Idd of the DC component deriving device 101 is integrated by the DC component integrating means 102. Is done. When the integration amount reaches a predetermined value, the DC component integration means 102 outputs and activates the one-shot timer 118, and a pulse having a predetermined time width is output. For this reason, even if the unlock signal is output from the inrush determiner 100, the inhibit means 119 is locked by the output of the one-shot timer 118 while CT is saturated.
Even if CT is saturated, there is no unnecessary output.

Embodiment 9 FIG. 13 is a block diagram showing a ratio differential relay device according to Embodiment 9 of the present invention. In the figure, reference numeral 120 denotes an output that integrates the output Idd of the DC component deriving device 101, and the integration amount is DC component integration. A second DC integration means for outputting when the detected value is equal to or more than a second predetermined value larger than the detection level of the means 102. Other configurations are shown in FIG.
Is the same as

Next, the operation will be described with reference to the waveform diagram of FIG. Differential current deriving device 12 to which inrush current is applied
The DC component in the output differential current Id is derived by the DC component deriving device 101, and the output Idd of the DC component deriving device 101 is integrated by the DC component integrating means 102. When the integration amount reaches the predetermined value after the time t _OP 102, the DC component integration means 102 outputs (g), and the second harmonic ratio sensitivity of the variable ratio inrush determiner 100 is changed from 12% to 8%, for example. I do. Further, the inrush current continues, and the operation time t _OP 120
When the detection level of the second DC component integrating means 120 reaches the detection level later, the second DC component integrating means 120 outputs (h), and the second harmonic ratio sensitivity of the variable inrush determiner 100 is set to, for example, 8 Change from% to 6%. Due to the two-stage reduction in sensitivity, even if CT is saturated by the inrush current and the second harmonic content in the differential current Id is reduced, the inrush determiner 100 does not output the unlock signal. Therefore, a signal for unnecessarily shutting down the transformer is not output from the AND circuit 17 at the time of inrush.

Embodiment 10 FIG. FIG. 15 is a block diagram showing a ratio differential relay device according to Embodiment 10 of the present invention. In the figure, reference numeral 121 denotes a high-voltage side terminal current I1.
DC component deriving device 123 for deriving a DC component therein; 123, first DC component integrating means for integrating the output of the DC component deriving device 121 and outputting when the integration amount is equal to or more than a predetermined value; 122, terminal current on the low voltage side DC component deriving device for deriving the DC component in I2, 124 is a second DC component integrating means for integrating the output of the DC component deriving device 122 and outputting when the integration amount is equal to or more than a predetermined value, and 125 is an inrush signal based on the output. 6 is an OR circuit that changes the second harmonic ratio sensitivity of the determiner 100.

Next, the operation will be described. For example, when an inrush current is applied from the high voltage side, the DC component in the high voltage side current I1 is derived by the first DC component deriving device 121, and the output of the first DC component deriving device 121 is the first DC component. Integration means 123
Is integrated by When the integration amount becomes equal to or more than a predetermined value, the first DC component integration means 123 outputs and changes the second harmonic ratio sensitivity of the variable ratio inrush determiner 100 from, for example, 12% to 8%. Due to this reduction in sensitivity, even if CT4 is saturated by the inrush current and the second harmonic content in the terminal current is reduced, the inrush determiner 100 does not output the unlock signal. Therefore, a signal for unnecessarily shutting down the transformer is not output from the AND circuit 17 at the time of inrush. The same operation is performed on the low pressure side. According to the tenth embodiment, as described above, not the differential current but the high-voltage side or the low-voltage side
Since the saturation of T is detected, it can be applied to the system shown in FIG. 16 as in the sixth and seventh embodiments.

[0047]

As described above, according to the present invention, the DC component in the differential current is extracted, and when the DC component is equal to or more than a predetermined value, it is determined that there is a risk of CT saturation. The non-inrush detection means is controlled prior to CT saturation to prevent malfunctions so that the non-inrush detection means does not output unnecessarily due to a decrease in the harmonic component content. A relay device is obtained.

The DC component in the differential current is extracted, and the DC component is integrated. When the integrated amount is equal to or more than a predetermined value, it is determined that there is a risk of CT saturation, and the second harmonic component content due to CT saturation is determined. Since the second harmonic ratio sensitivity of the inrush determiner is changed prior to the CT saturation so that the non-inrush detecting means does not output unnecessarily due to the decrease, the ratio differential relay device having high reliability is provided. Is obtained.

Further, a DC component in the differential current is extracted, and when a period in which the DC component exceeds a predetermined value continues for a predetermined time or more, it is determined that there is a risk of CT saturation, and the second harmonic component content due to CT saturation is determined. Since the second harmonic ratio sensitivity of the inrush determiner is changed prior to CT saturation so that the non-inrush detecting means does not output unnecessarily due to the rate reduction, a highly reliable ratio differential relay is provided. A device is obtained.

Further, the DC component in the differential current is extracted, and when the ratio of the DC component to the fundamental wave in the differential current exceeds a predetermined value continues for a predetermined time or more, it is determined that there is a risk of CT saturation. Then, the second harmonic ratio sensitivity of the inrush determination unit is changed prior to the CT saturation so that the non-inrush detecting means does not needlessly output due to a decrease in the second harmonic component content due to the CT saturation. Therefore, a highly reliable ratio differential relay can be obtained.

Further, the second harmonic component in the differential current is extracted, and when a period in which the magnitude ratio of the second harmonic to the fundamental wave in the differential current exceeds a predetermined value continues for a predetermined time or more, CT Judging that there is a risk of saturation, the second harmonic ratio sensitivity of the inrush determiner is set prior to CT saturation so that the non-inrush detection means does not needlessly output due to the reduction of the second harmonic component content due to CT saturation. Since the configuration is changed, a highly reliable ratio differential relay device can be obtained.

Further, the second harmonic component in the differential current is extracted, and if the second harmonic component tends to decrease, it is determined that there is a risk of CT saturation, and the content of the second harmonic component due to CT saturation is determined. Since the second harmonic ratio sensitivity of the inrush determiner is changed prior to the CT saturation so that the non-inrush detecting means does not output unnecessarily due to the decrease, the ratio differential relay device having high reliability is provided. Is obtained.

When the output obtained by adding the zero-phase current and each phase current of the high-voltage or low-voltage terminal is equal to or more than a predetermined value, it is determined that there is a risk of CT saturation, and the second harmonic component content reduction due to CT saturation occurs. The second harmonic ratio sensitivity of the inrush determiner is changed prior to CT saturation so that the non-inrush detection means does not output unnecessary.
A highly reliable ratio differential relay can be obtained.

Further, since the detection of the CT saturation due to the inrush current is detected not from the differential current but from the high voltage side or the low voltage side current, the present invention can be effectively applied to a system through which the inrush current passes.

When the ratio of the DC component to the fundamental wave in the output obtained by adding each phase current of the high voltage side terminal or the low voltage side terminal and the zero-phase current is equal to or more than a predetermined value, it is determined that the high voltage side CT may be saturated. In order to prevent unnecessary output of the non-inrush detecting means due to a decrease in the second harmonic component content due to CT saturation,
Since the second harmonic ratio sensitivity of the inrush determiner is changed prior to T saturation, a highly reliable ratio differential relay device can be obtained.

Further, a DC component in the differential current is extracted, and the DC component is integrated. When the integrated amount is equal to or more than a predetermined value, it is determined that there is a risk of CT saturation. In order to prevent the non-inrush detection means from outputting unnecessarily due to the decrease, a pulse of a predetermined time width is generated prior to the CT saturation, and the trip means is locked for the duration of the pulse output. For CT
And a highly reliable differential relay device that does not operate unnecessarily even when the voltage is saturated.

Further, a DC component in the differential current is extracted, and the DC component is integrated. When the integrated amount is equal to or more than a predetermined value, it is determined that there is a risk of CT saturation, and the content of the second harmonic component due to CT saturation is determined. The second harmonic ratio sensitivity of the inrush determiner is changed prior to CT saturation so that the non-inrush detection means does not output unnecessarily due to the decrease, and when the integration amount exceeds a second predetermined value or more, the inrush Since the second harmonic ratio sensitivity of the decision unit is further changed, a highly reliable ratio differential relay device that does not operate unnecessarily even when CT is saturated due to inrush current is obtained.

Further, a DC component in the high-voltage or low-voltage terminal current is extracted, and the DC component is integrated. When the integrated amount is equal to or more than a predetermined value, it is determined that there is a risk of CT saturation. The second harmonic ratio sensitivity of the inrush determiner is changed prior to CT saturation so that the non-inrush detection means does not output unnecessarily due to the decrease in the wave component content. And a highly reliable differential relay device that does not operate unnecessarily even when the voltage is saturated.

[Brief description of the drawings]

FIG. 1 is a block diagram of a ratio differential relay device according to Embodiment 1 of the present invention.

FIG. 2 is a waveform chart illustrating an operation of the first embodiment.

FIG. 3 is a block diagram of a ratio differential relay device according to Embodiment 2 of the present invention.

FIG. 4 is a block diagram of a ratio differential relay device according to Embodiment 3 of the present invention.

FIG. 5 is a waveform chart illustrating an operation of the third embodiment.

FIG. 6 is a block diagram of a ratio differential relay device according to Embodiment 4 of the present invention.

FIG. 7 is a waveform chart illustrating an operation of the fourth embodiment.

FIG. 8 is a block diagram of a ratio differential relay device according to Embodiment 5 of the present invention.

FIG. 9 is a waveform chart illustrating an operation of the fourth embodiment.

FIG. 10 is a block diagram of a ratio differential relay device according to Embodiment 6 of the present invention.

FIG. 11 is a block diagram of a ratio differential relay device according to Embodiment 7 of the present invention.

FIG. 12 is a block diagram of a ratio differential relay device according to Embodiment 8 of the present invention.

FIG. 13 is a block diagram of a ratio differential relay device according to Embodiment 9 of the present invention.

FIG. 14 is a waveform chart illustrating an operation of the ninth embodiment.

FIG. 15 is a block diagram of a ratio differential relay device according to Embodiment 10 of the present invention.

FIG. 16 is a system diagram showing a power system to which the sixth, seventh, and tenth embodiments are applied.

FIG. 17 is a system diagram showing a power system to which a conventional ratio differential relay device is applied.

FIG. 18 is a block diagram showing a conventional ratio differential relay device.

FIG. 19 is a waveform diagram illustrating an operation of the conventional ratio differential relay device when CT is not saturated.

FIG. 20 is a waveform diagram illustrating the operation of the conventional ratio differential relay device when CT is saturated.

[Explanation of symbols]

11 suppression current deriving device, 12 differential current deriving device, 13
Ratio differential device, 14, 15 filter, 16 inrush judgment device, 17 AND circuit, 20 non-inrush detection means, 100 variable ratio inrush judgment device, 10
1, 121, 122 DC component deriving device, 102, 120,
123, 125 DC component integrating means, 103, 112, 1
13 level detecting means, 104, 106, 108 timer, 105, 115, 116 DC component content rate detecting means,
107 second harmonic content detection means, 109 second harmonic decrease detection means, 110, 111 addition means, 114,
117, 124 OR circuit, 118 one-shot timer, 119 inhibit circuit.

Claims (14)

[Claims] 1. A suppression current deriving means for deriving a suppression current from each terminal current of a protected device, a differential current derivation means for deriving a differential current from each terminal current, and a predetermined relationship between the suppression current and the differential current. A differential output means for extracting the fundamental wave component and the second harmonic component in the differential current, and outputting when the ratio of the second harmonic component to the fundamental wave component is less than a predetermined value. Means, a direct current component detecting means for outputting when the direct current component in the differential current is equal to or more than a predetermined value, and a signal for shutting off the protected device from the system when there is an output from both the ratio differential device and the non-inrush detecting device. And a non-inrush detecting means is controlled by an output of the DC component detecting means, and an output is not output from the non-inrush detecting means at the time of inrush. Relay device. 2. A DC component detecting device, comprising: a DC component deriving device for deriving a DC component in a differential current; a DC component for integrating an output of the DC component deriving device; The ratio differential relay device according to claim 1, further comprising an integrating means. 3. The DC component detecting device includes: a DC component deriving device for deriving a DC component in a differential current; a DC component level detecting device for outputting when a magnitude of the DC component is equal to or greater than a predetermined value; 2. The ratio differential relay according to claim 1, further comprising timer means for outputting when the output of the detection means continues for a predetermined time. 4. A direct current component detecting device, comprising: a direct current component deriving device for deriving a direct current component in a differential current; and a direct current component output when a magnitude ratio of a direct current component to a fundamental wave in the differential current is a predetermined value or more. 2. The ratio differential relay device according to claim 1, further comprising: a minute component detection unit; and a timer unit that outputs when the output of the direct current component detection unit continues for a predetermined time. 5. A suppression current deriving means for deriving a suppression current from each terminal current of the protected device, a differential current deriving means for deriving a differential current from each terminal current, and a predetermined relationship between the suppression current and the differential current. A differential output means for extracting the fundamental wave component and the second harmonic component in the differential current, and outputting when the ratio of the second harmonic component to the fundamental wave component is less than a predetermined value. Means, a second harmonic detecting means for outputting in accordance with a ratio between a fundamental wave component and a second harmonic component in the differential current, and when there is output from both the ratio differential means and the non-inrush detecting means, An AND circuit for outputting a signal for shutting off the protected device from the system is provided, and the non-inrush detecting means is controlled by the output of the second harmonic detecting means. Nishiko And a ratio differential relay device. 6. The second harmonic detection means, wherein the second harmonic content detection means outputs when the ratio of the second harmonic component to the fundamental component in the differential current is equal to or greater than a predetermined value. 6. The ratio differential relay according to claim 5, further comprising timer means for outputting when the output of the harmonic content detection means continues for a predetermined time. 7. The second harmonic detecting means includes a second harmonic decrease detecting means for outputting when the ratio of the second harmonic to the fundamental in the differential current is decreasing by a predetermined value or more. The ratio differential relay device according to claim 5, wherein: 8. A suppression current deriving means for deriving a suppression current from each terminal current of the protected device, a differential current deriving means for deriving a differential current from each terminal current, and wherein the suppression current and the differential current have a predetermined relationship. Differential output means, a non-inrush detecting means for outputting when the ratio of the second harmonic component to the fundamental component in the differential current is equal to or less than a predetermined value, and each phase current of the high voltage side terminal or the low voltage side terminal And DC component detecting means for outputting in accordance with the added value of the zero-phase current, and when there is an output from both the ratio differential means and the non-inrush detecting means,
An AND circuit for outputting a signal for shutting off the device to be protected from the system is provided, and the non-inrush detecting means is controlled by the output of the DC component detecting means so that no output is output from the non-inrush detecting means at the time of inrush. A ratio differential relay device characterized by that: 9. The DC component detection means includes: an addition means for each phase current and a zero-phase current of the high voltage side terminal; an output level detection means for outputting when the output of the addition means is equal to or more than a predetermined value; Adding means for each phase current and zero-phase current, output level detecting means for outputting when the output of the adding means is equal to or more than a predetermined value, and an OR circuit for outputting a logical sum of the outputs of the two output level detecting means; 9. The ratio differential relay device according to claim 8, further comprising: 10. The DC component detecting means includes means for adding each phase current and the zero-phase current of the high voltage side terminal, and a DC component which is output when a ratio of a DC component to a fundamental wave in an output of the adding means is equal to or more than a predetermined value. Means for detecting share ratio, means for adding each phase current and zero-phase current of the low-voltage side terminal, and the DC component content output when the ratio of the DC component to the fundamental wave in the output of the adder is equal to or greater than a predetermined value. 9. The ratio differential relay device according to claim 8, further comprising detection means, and logical sum means for outputting a logical sum of outputs of the two direct current component content rate detection means. 11. A suppression current deriving means for deriving a suppression current from each terminal current of the protected device, a differential current derivation means for deriving a differential current from each terminal current, and a predetermined relationship between the suppression current and the differential current. A differential output means for extracting the fundamental wave component and the second harmonic component in the differential current, and outputting when the ratio of the second harmonic component to the fundamental wave component is less than a predetermined value. Means, DC component deriving means for deriving a DC component in the differential current, DC component integrating means for integrating the output of the DC component deriving means and outputting when the amount of integration is a certain value or more, once from the DC component integrating means. A one-shot timer that outputs a pulse of a predetermined time width when there is an output, an AND circuit that outputs a signal for shutting off the protected device from the system when there is an output from both the ratio differential means and the non-inrush detection means, and Wanshi A ratio differential relay device comprising an inhibit circuit that locks an output of the AND circuit by an output of a photo timer. 12. A DC component detecting means for DC component deriving means for deriving a DC component in a differential current, and integrating the output of the DC component deriving means, and outputting when the integrated amount is equal to or greater than a first predetermined value. And a second DC component integrating means for integrating the output of the DC component deriving means and outputting when the integrated amount is equal to or greater than a second predetermined value. The ratio differential relay according to claim 1. 13. A suppression current deriving means for deriving a suppression current from each terminal current of the protected device, a differential current deriving means for deriving a differential current from each terminal current, and wherein the suppression current and the differential current are predetermined. Ratio differential means for outputting when the relation is present, non-inrush detecting means for outputting when the ratio of the second harmonic current to the fundamental wave current in the differential current is equal to or less than a predetermined value, and direct current component in the high-side terminal current DC component deriving means, DC component integrating means for integrating the output of the DC component deriving means, and outputting when the integration amount is equal to or more than a predetermined value, DC component deriving means for deriving a DC component in the low-voltage side terminal current, DC integration means for integrating the output of the integration deriving means and outputting when the amount of integration is equal to or greater than a predetermined value, an OR circuit for outputting the logical sum of the outputs of the DC integration means, and From inrush detection means When both outputs are provided, an AND circuit for outputting a signal for shutting off the protected device from the system is provided, and the non-inrush detecting means is controlled by the output of the OR circuit. Ratio differential relay device, characterized in that it does not emit a signal. 14. A non-inrush detecting means, comprising: a fundamental filter for extracting a fundamental component in the differential current; a second harmonic filter for extracting a second harmonic component; and a second harmonic filter for the fundamental component. At the same time as determining the ratio of harmonic components,
14. The ratio differential relay device according to claim 1, further comprising a variable ratio inrush determiner capable of controlling the ratio sensitivity of the second harmonic by an external signal. .