JPH11341680A - Ratio differential relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the malfunctioning factor of a ratio differential relay when it is in an inrush state, and reduce its erroneously unoperating factor when its inner fault is generated, by outputting a trip signal to separate transformers from an electric power system when a determining result shows that it is not in the inrush state, in the case of the integration result of its integrator not larger than a reference value. SOLUTION: In the case of no saturation sensing signal being outputted from an integrator 29, when a fault sensing signal is outputted from a logical multiply circuit 27, an inhibit 30 outputs a trip command. Against this, there is adopted a respective-phase tripping method for separating transformers from an electric power system even when no trip command is outputted from a logical multiply circuit 31. In this way, there is provided a constitution wherein while an inrush determining device 26 outputs an unlocking signal, in the case of the integrator 29 outputting no saturation sensing signal, the transformers are separated from the electric power system when a ratio differential device 23 outputs a trip signal. Therefore, the malfunctioning factor of a ratio differential relay is reduced when it is in an inrush state, and its erroneously unoperating factor can be reduced when its inner fault is generated.

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 device for preventing a malfunction due to an inrush current and for surely disconnecting a transformer from a power system when an internal accident of the transformer occurs.

[0002]

2. Description of the Related Art FIG. 11 is a system diagram showing a power system to which a conventional ratio differential relay device is applied. In the figure, reference numeral 1 denotes a transformer to be protected, and 2 denotes a transformer connected to a high voltage side of a transformer 1. Current detectors 2A, 2B and 2C are the primary current I of the transformer 1.
_{1A (= I A -I C)} , I 1B (= I B -I A), I 1C (=
Current transformer (hereinafter, referred to as “CT”) for measuring I _C −I _B ), 3 is a current detector connected to the low voltage side of the transformer 1,
3a, 3b, 3c are secondary currents I _2a of the transformer 1 (= I _a −
_{I c), I 2b (=} I b -I a), I 2c (= I c -I b)
Current transformer (hereinafter referred to as “CT”), 4 is a ratio differential relay that cuts off the transformer 1 from the power system when an internal accident FI occurs in the power system, and 4A is measured by CT2A. The internal fault detector 4B detects the internal fault FI from the primary current I _1A and the secondary current I _2a measured by the CT 3a, and the primary currents I _1B and C measured by the CT 2B.
Internal fault FI from the secondary current I _2b measured by T3b
Internal fault detector for detecting, 4C is an internal fault detector for detecting an internal fault FI from the secondary current I _2C measured by the primary current I _1C and CT3c measured by CT2C.

[0003] Figure 12 is a block diagram showing a conventional proportions differential relay apparatus shown in, for example, JP-A 5-316636, reference numeral 11 is the primary current I _1A and CT3a measured by CT2A A suppression current deriving unit that compares the measured secondary current I _2a and derives a current having a larger current value as a suppression current Ir. Reference numeral 12 denotes a primary current I _1A measured by CT2A and a secondary current measured by CT3a. A differential current deriving device for deriving a vector difference of the current I _2a as a differential current Id; a ratio differential device for outputting a trip signal when a ratio of the differential current Id to the suppression current Ir exceeds a reference level; A fundamental wave filter for extracting a fundamental wave component Id0 included in the differential current Id derived by the differential current deriving device 12, and a differential current Id derived by the differential current deriving device 12 The second harmonic filter 16 for extracting the second harmonic component Id2 included therein has a current value of the differential current Id equal to or more than a predetermined value, and a ratio of the second harmonic component Id2 to the fundamental wave component Id0 is a reference level. In the following cases, it is determined that the vehicle is not in the inrush state, and an inrush determiner 17 outputs a non-lock signal. A trip signal is output from the ratio differential unit 13 and an inrush determiner 16 is output.
Is a logical product circuit that outputs an accident detection signal when a non-lock signal is output from the controller.

An AND circuit 18 disconnects the transformer 1 from the power system when an accident detection signal is output from the internal accident detector 4A and an accident detection signal is output from the internal accident detector 4B. Reference numeral 19 denotes a logical product circuit for disconnecting the transformer 1 from the power system when an accident detection signal is output from the internal accident detector 4B and an accident detection signal is output from the internal accident detector 4C. When a fault detection signal is output from the transformer 4C and a fault detection signal is output from the internal fault detector 4A, the AND circuit shuts off the transformer 1 from the power system.

Next, the operation will be described. First, as shown in FIG. 11, the general function of the ratio differential relay device 4 is that the transformer 1 is not cut off from the power system even if an external fault FO occurs in the power system, but the internal fault FI When a fault occurs, a trip command is output to a circuit breaker (not shown) by detecting the internal accident FI to cut off the transformer 1 from the power system.

Next, the operation of the ratio differential relay device 4 will be described in detail. The operation of the internal fault detectors 4A, 4B, and 4C constituting the ratio differential relay device 4 depends on the equipment configuration. Since they are the same (the input currents are different), the operation of the internal accident detector 4A will be described here for convenience of explanation. First, the suppression current deriving unit 11 outputs the primary current I _1A measured by CT2A and the secondary current I _2a measured by CT3a.
And the current having the larger current value is derived as the suppression current Ir. The differential current derivation unit 12 calculates the vector difference of the secondary current I _2a measured by the measured primary current I _1A and CT3a by CT2a, derives the vector difference as a differential current Id.

As described above, when the suppression current Ir and the differential current Id are derived, the ratio differentiator 13 generally operates when the ratio of the differential current Id to the suppression current Ir exceeds the reference level. Since the probability of occurrence of the internal accident FI in the power system is high, a trip signal is output when the following conditions are satisfied. Id> KF1 × Ir + KM where KF1 and KM are predetermined constants

As a result, an internal accident F
When I occurs, the transformer 1 can be disconnected from the power system. However, when the power system is in an inrush state, an inrush current flows into the transformer 1, so that the internal A phenomenon similar to the case where the accident FI occurs occurs. Therefore, when the power system is in the inrush state, a trip signal may be output from the ratio differential unit 13. However, since the inrush state is different from the internal accident FI in the power system, the transformer 1
Need to be isolated from the power grid.

The inrush determiner 16 has a property that the inrush current contains a larger amount of the second harmonic component Id2 than the fault current when the internal fault FI occurs.
When the fundamental wave filter 14 extracts the fundamental wave component Id0 included in the differential current Id and the second harmonic filter 15 extracts the second harmonic component Id2 included in the differential current Id, the fundamental wave component Id0 is extracted. When the ratio of the second harmonic component Id2 is equal to or lower than the reference level, it is determined that the vehicle is not in the inrush state, and a non-lock signal is output (when the following inequality holds). On the other hand, when the ratio of the second harmonic component Id2 to the fundamental wave component Id0 exceeds the reference level, it is determined that the vehicle is in the inrush state, and the output of the unlock signal is released (when the following inequality does not hold). ). Id2 <KF2 × Id0 where KF2 is a predetermined constant

The AND circuit 17 is provided with the ratio differential 1
3, when the trip signal is output from the inrush determiner 16 and the unlock signal is output from the inrush determiner 16, it is determined that an internal fault FI has occurred in the power system, and an fault detection signal is output (inrush determiner If the unlock signal is not output from 16, it is in the inrush state,
Even if the trip signal is output from the ratio differential 13, the fault detection signal is not output). As a result, as long as the CT 2A or the like accurately measures the primary current I _1A or the like, the inrush state is correctly determined, and the transformer 1 is activated when the inrush state occurs.
Can be prevented from being disconnected from the power system.

However, when the inrush current flows into the transformer 1, for example, the CT 2A measures the inrush current. However, since the inrush current contains many DC components, the fourth wave of the inrush current is measured. The core of CT2A is saturated from the moment (CT2A is saturated when the integration result of the DC component exceeds a predetermined value), and the primary current I _1A which is the measured value of CT2A shows a waveform different from the actual inrush current. (See FIG. 13).

That is, the primary current I output by CT2A
_1A shows a typical half-wave inrush current waveform without saturation at about the third wave of the inrush current, but from the fourth wave of the inrush current, due to the effect of saturation, current waveform I _1A becomes shape swings between positive and negative, when this harmonic analyzing increases the ratio of the third harmonic component, and that the ratio of the second harmonic component is reduced. For this reason,
When the current reaches about the sixth wave of the inrush current, the inrush determiner 16 erroneously determines that the inrush current is not present, and outputs a non-lock signal.

As a result, there occurs a problem that the AND circuit 17 outputs an accident detection signal in an inrush state other than the internal accident FI. However, and the primary current I _1B delay phase to the primary current I _1A, the primary current I proceeds phase to _1A the primary current I _1C is not necessarily the second harmonic component is reduced, in this case, internal fault Detector 4B, 4C
Does not output the accident detection signal from the AND circuit 17 (see FIG. 13).

Therefore, in order to prevent as much as possible the problem of outputting an accident detection signal in the in-rush state, at least two or more of the internal accident detectors 4A, 4B and 4C output the accident detection signal. Only when the transformer 1 is disconnected from the power system, a two-phase AND method (A and B phases, B and C phases, or C and A phases) is adopted,
AND circuits 18, 19 and 20 are added. The ratio differential relay is a relay for short-circuit protection. However, in the case of an internal short-circuit fault (two-phase short-circuit, three-phase short-circuit), at least a two-phase internal fault detector outputs an fault detection signal. Therefore, even in the two-phase AND system, the transformer 1 can be disconnected from the power system.

[0015]

Since the conventional ratio differential relay device is configured as described above, unnecessary operation of disconnecting the transformer 1 from the power system when the power system is in an inrush state is provided. Although it can be avoided, even when an internal accident occurs, each phase trip method (any one of the internal When a signal is output, the malfunction rate at the time of occurrence of an internal accident doubles as compared with the method of disconnecting the transformer 1 from the power system).

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can reduce a malfunction rate in an inrush state and a malfunction rate in an internal accident. It is an object to obtain a differential relay having a ratio that can be obtained.

[0017]

A ratio differential relay device according to the present invention indicates that the determination result of the determination means is not in an inrush state, and that the integration result of the integration means is equal to or less than a reference value. When the ratio differential means outputs a trip signal, the transformer is disconnected from the power system.

In the ratio differential relay device according to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the integrating means is provided with an integrating means. Even when the integration result exceeds the reference value, the transformer is cut off from the power system.

In the ratio differential relay device according to the present invention, when the ratio differential unit outputs a trip signal when the DC component detected by the detection unit does not exceed the reference value for a predetermined period of time, the voltage is changed. In this case, the heater is disconnected from the power system.

In the ratio differential relay device according to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the detection means detects the trip signal. Even when the detected DC component continuously exceeds the reference value for a predetermined time, the transformer is cut off from the power system.

In the ratio differential relay device according to the present invention, the determination result of the determination means indicates that the inrush state is not present, and the ratio of the DC component to the fundamental wave component detected by the detection means continues for a predetermined time. When the ratio does not exceed the reference ratio, when the ratio differential means outputs a trip signal, the transformer is cut off from the power system.

According to the ratio differential relay device of the present invention, when a plurality of ratio differential units among the ratio differential units connected to each phase of the transformer output a trip signal, the detection unit detects the trip signal. The transformer is cut off from the power system even when the ratio of the detected DC component to the fundamental component exceeds the reference ratio for a predetermined period of time.

In the ratio differential relay device according to the present invention, the determination result of the determination means indicates that the state is not in an inrush state, and the ratio of the second harmonic component to the fundamental wave component detected by the detection means is predetermined. When the reference ratio does not exceed the reference ratio continuously for a period of time, when the ratio differential means outputs a trip signal, the transformer is disconnected from the power system.

In the ratio differential relay device according to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the detection means detects the trip signal. Even when the ratio of the second harmonic component to the detected fundamental component exceeds the reference ratio for a predetermined time, the transformer is disconnected from the power system.

According to the ratio differential relay device of the present invention, when the determination result of the determination means indicates that the vehicle is not in an inrush state, and the reduction rate detected by the detection means is smaller than the reference reduction rate, When the differential means outputs a trip signal, the transformer is disconnected from the power system.

In the ratio differential relay device according to the present invention, when a plurality of ratio differential units among the ratio differential units connected to each phase of the transformer output a trip signal, the detection unit detects the trip signal. Even when the detected reduction rate is larger than the reference reduction rate, the transformer is disconnected from the power system.

The ratio differential relay device according to the present invention indicates that the determination result of the determination means is not in an inrush state, and that if the addition result of the addition means is equal to or less than the reference value, the ratio differential relay means When a trip signal is output, the transformer is disconnected from the power system.

According to the ratio differential relay device of the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the adding means can be used. Even when the addition result exceeds the reference value, the transformer is disconnected from the power system.

The ratio differential relay device according to the present invention is characterized in that the judgment result of the judging means indicates that there is no inrush state, and the ratio of the DC component to the fundamental wave component included in the added current is equal to or less than the reference ratio. When the ratio differential means outputs a trip signal, the transformer is disconnected from the power system.

In the ratio differential relay device according to the present invention, when a plurality of ratio differential units among the ratio differential units connected to each phase of the transformer output a trip signal, the added current is reduced. Even if the ratio of the DC component to the included fundamental wave component exceeds the reference ratio, the transformer is cut off from the power system.

In the ratio differential relay device according to the present invention, when the judgment result of the judging means indicates that the inrush state has not occurred, and the integration result of the DC component included in the input current or the output current is equal to or less than the reference value, When the ratio differential means outputs a trip signal, the transformer is disconnected from the power system.

In the ratio differential relay device according to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the input current or Even if the integration result of the DC component included in the output current exceeds a reference value, the transformer is cut off from the power system.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing a ratio differential relay device according to Embodiment 1 of the present invention.
Is a suppression current deriving unit (current deriving means) which compares the primary current I _1A measured by CT2A with the secondary current I _2a measured by CT3a, and derives a current having a larger current value as suppression current Ir, 22 Is a differential current deriving unit (current deriving means) for deriving a vector difference between the primary current I _1A measured by CT2A and the secondary current I _2a measured by CT3a as a differential current Id, and 23 is a difference with respect to the suppression current Ir. When the ratio of the dynamic current Id exceeds the reference level, a ratio differential device (ratio differential means) that outputs a trip signal, 24 is a fundamental wave component Id0 included in the differential current Id derived by the differential current derivation device 22 Is a fundamental wave filter (judgment means) for extracting the second harmonic component Id2 contained in the differential current Id derived by the differential current deriving device 22. Means), 26, when the current value of the differential 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 the reference level, determine that the vehicle is not in the inrush state; An inrush determining unit (determining means) 27 that outputs a lock signal outputs an accident detection signal when a trip signal is output from the ratio differential unit 23 and a non-lock signal is output from the inrush determining unit 26. AND circuit (interruption means).

Reference numeral 28 denotes a DC component deriving unit (detection means, integrating means) for deriving a DC component Idd included in the differential current Id derived by the differential current deriving unit 22, and 29 denotes a DC component deriving unit 28. An integrator (integrating means) that integrates the derived DC component Idd and outputs a saturation detection signal when the integration result exceeds a reference value. When an integrator 29 does not output a saturation detection signal, AND circuit 2
7 is an inhibit (cutoff means) for outputting a trip command when an accident detection signal is output, and 31 is an internal accident detector 4A.
Outputs an accident detection signal, and the internal accident detector 4
When an accident detection signal is output from B, an AND circuit (interrupting means) for outputting a trip command,
This is a logical sum circuit (interruption means) that shuts off the transformer 1 from the power system when at least one of 0 and the AND circuit 31 outputs a trip command.

Further, if the saturation detection signal is not output from the integrator 29 of the internal accident detector 4B, the reference numeral 33 indicates
When the AND circuit 27 of the internal accident detector 4B outputs an accident detection signal, an inhibit (blocking means) that outputs a trip command is output from the internal accident detector 4B. When an accident detection signal is output from the inverter, an AND circuit (shut-off means) for outputting a trip command, and when at least one of the inhibit 33 or the AND circuit 34 outputs a trip command, the transformer 1 is cut off from the power system. When the saturation detection signal is not output from the integrator 29 of the internal fault detector 4C, the logical sum circuit (blocking means) 36 performs the operation when the AND circuit 27 of the internal fault detector 4C outputs the fault detection signal. An inhibit (shutoff means) 37 for outputting a trip command outputs an accident detection signal from the internal accident detector 4C. When fault detection signal is output, the AND circuit for outputting a trip command (blocking means),
Reference numeral 38 denotes a logical sum circuit (blocking means) that blocks the transformer 1 from the power system when at least one of the inhibit 36 and the AND circuit 37 outputs a trip command.

Next, the operation will be described. First, as shown in FIG. 11, the general function of the ratio differential relay device 4 is that the transformer 1 is not cut off from the power system even if an external fault FO occurs in the power system, but the internal fault FI When a fault occurs, a trip command is output to a circuit breaker (not shown) by detecting the internal accident FI to cut off the transformer 1 from the power system.

Next, the operation of the ratio differential relay device 4 will be specifically described. The operation of the internal fault detectors 4A, 4B, and 4C that constitute the ratio differential relay device 4 is as follows. Since they are the same (the input currents are different), the operation of the internal accident detector 4A will be described here for convenience of explanation. First, the suppression current deriving unit 21 outputs the primary current I _1A measured by CT2A and the secondary current I _2a measured by CT3a.
And the current having the larger current value is derived as the suppression current Ir. The differential current derivation unit 22 calculates the vector difference of the secondary current I _2a measured by the measured primary current I _1A and CT3a by CT2a, derives the vector difference as a differential current Id.

As described above, when the suppression current Ir and the differential current Id are derived, the ratio differential device 23 generally operates when the ratio of the differential current Id to the suppression current Ir exceeds the reference level. Since the probability of occurrence of the internal accident FI in the power system is high, a trip signal is output when the following conditions are satisfied. Id> KF1 × Ir + KM where KF1 and KM are predetermined constants

As a result, the internal accident F
When I occurs, the transformer 1 can be disconnected from the power system. However, when the power system is in an inrush state, an inrush current flows into the transformer 1, so that the internal A phenomenon similar to the case where the accident FI occurs occurs. Therefore, when the power system is in the inrush state, a trip signal may be output from the ratio differential 23, but since the inrush state is different from the internal accident FI in the power system, the transformer 1
Need to be isolated from the power grid.

Therefore, the inrush determiner 26 has a property that the inrush current contains a larger amount of the second harmonic component Id2 than the fault current when the internal fault FI occurs.
When the fundamental wave filter 24 extracts the fundamental wave component Id0 included in the differential current Id and the second harmonic filter 25 extracts the second harmonic component Id2 included in the differential current Id, the fundamental wave component Id0 is extracted. When the ratio of the second harmonic component Id2 is equal to or lower than the reference level, it is determined that the vehicle is not in the inrush state, and a non-lock signal is output (when the following inequality holds). On the other hand, when the ratio of the second harmonic component Id2 to the fundamental wave component Id0 exceeds the reference level, it is determined that the vehicle is in the inrush state, and the output of the unlock signal is released (when the following inequality does not hold). ). Id2 <KF2 × Id0 where KF2 is a predetermined constant

The AND circuit 27 is provided with the differential
3, when the trip signal is output from the inrush determiner 26 and the unlock signal is output from the inrush determiner 26, it is determined that an internal fault FI has occurred in the power system, and an fault detection signal is output (inrush determiner If no unlock signal is output from 26, it is in an inrush state,
Even if the trip signal is output from the ratio differential unit 23, no fault detection signal is output). As a result, as long as the CT 2A or the like accurately measures the primary current I _1A or the like, the inrush state is correctly determined, and the transformer 1 is activated when the inrush state occurs.
Can be prevented from being disconnected from the power system.

However, when the inrush current flows into the transformer 1, for example, the CT 2 A measures the inrush current. However, since the inrush current contains many DC components, the fourth wave of the inrush current is measured. The core of CT2A is saturated from the moment (CT2A is saturated when the integration result of the DC component exceeds a predetermined value), and the primary current I _1A which is the measured value of CT2A shows a waveform different from the actual inrush current. (See FIG. 2).

That is, the primary current I output by CT2A
_1A shows a typical half-wave inrush current waveform without saturation at about the third wave of the inrush current, but from the fourth wave of the inrush current, due to the effect of saturation, current waveform I _1A becomes shape swings between positive and negative, when this harmonic analyzing increases the ratio of the third harmonic component, and that the ratio of the second harmonic component is reduced. For this reason,
When the current reaches about the sixth wave of the inrush current, the inrush determiner 26 erroneously determines that the inrush current is not present, and outputs a non-lock signal.

As a result, there occurs a problem that the AND circuit 27 outputs an accident detection signal in an inrush state other than the internal accident FI. However, and the primary current I _1B delay phase to the primary current I _1A, the primary current I proceeds phase to _1A the primary current I _1C is not necessarily the second harmonic component is reduced, in this case, internal fault Detector 4B, 4C
Does not output the accident detection signal from the AND circuit 27 (see FIG. 2).

Therefore, in order to prevent as much as possible the problem of outputting an accident detection signal during the inrush state, at least two or more of the internal accident detectors 4A, 4B and 4C output the accident detection signal. Only when the transformer 1 is disconnected from the power system, a two-phase AND method (A and B phases, B and C phases, or C and A phases) is adopted,
AND circuits 31, 34, and 37 are added.

As described above, when the two-phase AND system is adopted, unnecessary operation of disconnecting the transformer 1 from the power system when the power system is in an inrush state can be avoided. If an internal accident occurs, two or more internal accident detectors must output an accident detection signal when an internal accident occurs. When the output is performed, a malfunction occurs in which the malfunction rate at the time of occurrence of an internal accident is doubled as compared with the method of disconnecting the transformer 1 from the power system.

Therefore, in the first embodiment, the CT2A
And the like are in a saturated state, the two-phase AND method is adopted. If the CT2A and the like are not in a saturated state, each phase trip method is adopted. That is, when the DC component deriving unit 28 derives the DC component Idd included in the differential current Id, the integrator 29 integrates the DC component Idd,
If the integration result exceeds the reference value, it is determined that CT2A and the like are in a saturated state, and a saturation detection signal is output (see FIG. 2).

Accordingly, when the saturation detection signal is output from the integrator 29, the inhibit command does not output a trip command even if the accident detection signal is output from the AND circuit 27. Do not disconnect the transformer 1 from the power system unless a trip command is output 2
A phase AND method is adopted. On the other hand, when the saturation detection signal is not output from the integrator 29 and the accident detection signal is output from the AND circuit 27, the inhibit 30 outputs the trip instruction, so the trip instruction is output from the AND circuit 31. Even if there is no transformer, each phase trip method that disconnects the transformer 1 from the power system is adopted.

As is apparent from the above, the first embodiment
According to the above, when the inrush determiner 26 outputs the unlock signal and the integrator 29 does not output the saturation detection signal, when the ratio differential unit 23 outputs the trip signal,
Since the transformer 1 is configured to be disconnected from the power system,
This has the effect of reducing the malfunction rate in the in-rush state and reducing the malfunction rate in the event of an internal accident.

Embodiment 2 FIG. 3 is a configuration diagram showing a ratio differential relay device according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. Reference numeral 39 denotes a level detector (detection means) which notifies a timer 40 when the DC component Idd derived by the DC component deriver 28 exceeds a reference value.
Reference numeral 0 denotes a timer (detection means) that outputs a saturation detection signal when a notification from the level detector 39 that the DC component Idd continuously exceeds the reference value for a predetermined time (for example, one second).

Next, the operation will be described. In the first embodiment, when the integration result of the integrator 29 exceeds the reference value,
Although the case where the CT2A or the like is determined to be in a saturated state and outputs a saturation detection signal has been described, for example, if the DC component Idd continuously exceeds 10% of the rated current, the CT2A or the like is saturated. It may be determined that the state is in the state (at the time of an internal accident, the DC component Idd usually does not exceed 10% of the rated current for a predetermined time).

That is, the level detector 39 detects the DC component Id
When detecting that d has exceeded the reference value, the timer 40 starts counting. Then, if the notification that the DC component Idd has become equal to or less than the reference value is not received from the level detector 39 before the count value of the timer 40 overflows, it is determined that the CT2A or the like is in a saturated state. , And outputs a saturation detection signal.

Thus, similar to the first embodiment,
This has the effect of reducing the malfunction rate in the in-rush state and reducing the malfunction rate in the event of an internal accident.

Embodiment 3 FIG. FIG. 4 is a configuration diagram showing a ratio differential relay device according to Embodiment 3 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. A ratio detector 41 detects a ratio Idd / Id0 of the DC component Idd to the fundamental wave component Id0 extracted by the fundamental wave filter 24, and notifies the timer 42 when the ratio Idd / Id0 exceeds the reference ratio. (Detection means), 42 receives a notification from the ratio detector 41 that the ratio Idd / Id0 continuously exceeds the reference ratio for a predetermined time (for example, one second) and outputs a saturation detection signal (detection means). It is.

Next, the operation will be described. In the second embodiment, when the DC component Idd included in the differential current Id continuously exceeds the reference value for a predetermined time, it is determined that the CT2A or the like is in a saturated state, and a saturation detection signal is output. However, for example, when the ratio Idd / Id0 of the DC component Idd to the fundamental wave component Id0 continuously exceeds 40%, it may be determined that the CT2A or the like is in a saturated state (in the case of an internal accident, , Usually the fundamental component I
The ratio Idd / Id0 of the DC component Idd to d0 does not exceed 40% continuously for a predetermined period of time).

That is, the ratio detector 41 outputs the fundamental wave component Id0.
When it is detected that the ratio Idd / Id0 of the DC component Idd to the current exceeds the reference ratio, the timer 42 starts counting. Before the count value of the timer 42 overflows, the ratio Idd /
If the notification that Id0 has become equal to or less than the reference ratio is not received, it is determined that the CT2A or the like is in a saturated state, and a saturation detection signal is output.

Thus, similar to the second embodiment,
This has the effect of reducing the malfunction rate in the in-rush state and reducing the malfunction rate in the event of an internal accident.

Embodiment 4 FIG. 5 is a configuration diagram showing a ratio differential relay device according to Embodiment 4 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. A ratio detector (detection means) 43 detects a ratio Id2 / Id0 of the second harmonic component Id2 to the fundamental wave component Id0, and notifies the timer 44 when the ratio Id2 / Id0 exceeds the reference ratio. 44
Is a timer (detection means) that outputs a saturation detection signal when it is notified from the ratio detector 43 that the ratio Id2 / Id0 continuously exceeds the reference ratio for a predetermined time (for example, one second).

Next, the operation will be described. In the third embodiment, when the ratio Idd / Id0 of the DC component Idd to the fundamental wave component Id0 exceeds the reference ratio for a predetermined time, it is determined that the CT2A or the like is in a saturated state, and a saturation detection signal is output. Is shown, but for example,
If the ratio Id2 / Id0 of the second harmonic component Id2 to the fundamental component Id0 continuously exceeds 12%, C
It may be determined that T2A or the like is in a saturated state. (In the case of an internal accident, the ratio Id2 / Id0 of the second harmonic component Id2 to the fundamental component Id0 usually does not exceed 12% for a predetermined time. Absent).

That is, the ratio detector 43 detects the fundamental wave component Id0.
When it is detected that the ratio Id2 / Id0 of the second harmonic component Id2 to the reference ratio exceeds the reference ratio, the timer 44 starts counting. Then, before the count value of the timer 44 overflows, the ratio I
If the notification that d2 / Id0 has become equal to or less than the reference ratio is not received, it is determined that the CT2A or the like is in a saturated state, and a saturation detection signal is output.

Thus, similar to the third embodiment,
This has the effect of reducing the malfunction rate in the in-rush state and reducing the malfunction rate in the event of an internal accident.

Embodiment 5 FIG. 6 is a configuration diagram showing a ratio differential relay device according to Embodiment 5 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. 45 detects a reduction rate of the ratio Id2 / Id0 of the second harmonic component Id2 to the fundamental wave component Id0, and if the reduction rate is smaller than the reference reduction rate, a reduction rate detector (detection) that outputs a saturation detection signal. Means).

Next, the operation will be described. In the fourth embodiment, the second harmonic component I with respect to the fundamental component Id0
When the ratio Id2 / Id0 of d2 continuously exceeds the reference ratio for a predetermined period of time, it is determined that the CT2A or the like is in a saturated state and a saturation detection signal is output. Second harmonic component Id2
Decrease rate of the ratio Id2 / Id0 of the reference rate (for example,
If it is smaller than −2% / cycle), it may be determined that the CT2A or the like is in a saturated state (the inrush current itself on the CT primary side usually has no fundamental wave component Id0 when there is no CT saturation). The ratio Id2 / Id0 of the second harmonic component Id2 to the ratio tends to slightly increase).

That is, the reduction rate detector 45 outputs the fundamental wave component I
Ratio Id2 / Id of second harmonic component Id2 to d0
If the decrease rate of 0 is smaller than the reference decrease rate, CT2A
Are determined to be in a saturated state, and a saturation detection signal is output.

Thus, similar to the fourth embodiment,
This has the effect of reducing the malfunction rate in the in-rush state and reducing the malfunction rate in the event of an internal accident.

Embodiment 6 FIG. FIG. 7 is a configuration diagram showing a ratio differential relay device according to Embodiment 6 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. 46 is the primary current I _1A , I of the transformer 1
An adder (adding means) for adding the _1B , I _1C and the zero-phase current I _1N to each other; 47, a level detector (adding means) for outputting a saturation detection signal when the addition result of the adder 46 exceeds a reference value; 48 is an adder (adding means) for adding the secondary currents I _2a , I _2b , I _2c of the transformer 1 and the zero-phase current I _2n to each other;
Is a level detector (adding means) that outputs a saturation detection signal when the addition result of the adder 48 exceeds the reference value. When at least one of the level detector 47 and the level detector 49 outputs a saturation detection signal, An OR circuit (adding means) for outputting the saturation detection signal to the inhibits 30, 33, 36.

Next, the operation will be described. In the fifth embodiment, the second harmonic component I with respect to the fundamental component Id0
When the reduction rate of the ratio Id2 / Id0 of d2 is smaller than the reference reduction rate, it is determined that the CT2A or the like is in a saturated state and a saturation detection signal is output.
The saturation state of CT2A or the like may be determined as follows.

That is, when CT2A and the like are not saturated,
The primary currents I _1A , I _1B ,
The sum of I _1C and the zero-phase current I _1N is zero, and the sum of the secondary currents I _2a , I _2b , I _2c and the zero-phase current I _2n is zero. However, when any of the CTs saturates, their sum will no longer be zero.

Therefore, in the sixth embodiment, the adder 4
6 is the primary current I _1A , I _1B , I _1C of the transformer ₁ and the zero-phase current I
_1N are added to each other, and the adder 48 outputs the secondary current I
_2a , I _2b and I _2c and the zero-phase current I _2n are added to each other. When the addition result of the adder 46 exceeds the reference value, the level detector 47 determines that the CT2A or the like is in a saturated state and outputs a saturation detection signal. If the addition result exceeds the reference value, it is determined that CT3a and the like are in a saturated state, and a saturation detection signal is output. When at least one of the level detector 47 and the level detector 49 outputs a saturation detection signal, the OR circuit 50 outputs the saturation detection signal to the inhibits 30 and 3.
3 and 36.

Thus, similar to the fifth embodiment,
This has the effect of reducing the malfunction rate in the in-rush state and reducing the malfunction rate in the event of an internal accident.

It should be noted that the first to fifth embodiments are described.
Now, the differential current I derived by the differential current
Although the case of determining the saturation state of CT2A or the like based on d has been described, in the case of the sixth embodiment, based on the primary currents I _1A , I _1B , I _1C and the secondary currents I _2a , I _2b , I _2c . To determine the saturation state of CT2A etc.
The ratio differential relay device can be applied to a power system as shown in FIG.

That is, while the transformer 1 is operating (the circuit breakers 5 and 6 are closed), when the circuit breaker 7 connected to the transformer 9 is turned on (the circuit breaker 8 is open), the inrush current becomes C
It becomes a form penetrating T2 and CT3, and the ratio differential relay 4
Cannot detect the differential current Id. For this reason, even if the CT2A or the like is saturated, the above-described first to fifth embodiments cannot detect the saturated state of the CT2A or the like. However, in the sixth embodiment, based on the primary current I _1A or the like, Therefore, even if the differential current Id cannot be detected, the CT
A saturated state such as 2A can be detected.

Embodiment 7 FIG. 9 is a configuration diagram showing a ratio differential relay device according to Embodiment 7 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a description thereof will not be repeated. 51 is a ratio I of the DC component Idd to the fundamental component Id0 included in the addition result of the adder 46.
dd / Id0 is detected, and when the ratio Idd / Id0 exceeds the reference ratio, a ratio detector (detection means) 52 for outputting a saturation detection signal is provided with a direct current (DC) for the fundamental wave component Id0 included in the addition result of the adder 48. Ratio Idd of component Idd
/ Id0 is detected, and when the ratio Idd / Id0 exceeds the reference ratio, a ratio detector (detection means) 53 for outputting a saturation detection signal, and at least one of the ratio detector 51 or the ratio detector 52 outputs the saturation detection signal. Is output, the OR circuit (detection means) outputs the saturation detection signal to the inhibits 30, 33, and 36.

In the sixth embodiment, the adders 46 and 48
When the addition result exceeds the reference value, it is determined that the CT2A or the like is in a saturated state and a saturation detection signal is output. However, the DC component I with respect to the fundamental wave component Id0 is shown.
When the dd ratio Idd / Id0 exceeds the reference ratio,
It may be determined that CT2A or the like is in a saturated state.

That is, the ratio detector 51 outputs the DC component I to the fundamental component Id 0 included in the addition result of the adder 46.
When detecting that the ratio Idd / Id0 of dd exceeds the reference ratio, a saturation detection signal is output, and the ratio detector 52 outputs the ratio Idd / of the DC component Idd to the fundamental wave component Id0 included in the addition result of the adder 48. When it detects that Id0 has exceeded the reference ratio, it outputs a saturation detection signal. When at least one of the ratio detector 51 and the ratio detector 52 outputs the saturation detection signal, the OR circuit 53 outputs the saturation detection signal to the inhibits 30, 33, and 36.

Thus, similar to the sixth embodiment,
This has the effect of reducing the malfunction rate in the in-rush state and reducing the malfunction rate in the event of an internal accident. Further, similarly to the sixth embodiment, even if the differential current Id cannot be detected, an effect of detecting a saturated state of the CT2A or the like can be obtained.

Embodiment 8 FIG. FIG. 10 is a configuration diagram showing a ratio differential relay device according to Embodiment 8 of the present invention. In the figure, the same reference numerals as in FIG. 1 denote the same or corresponding parts, and a description thereof will be omitted. Reference numeral 54 denotes a DC component deriving unit (integrating means) for deriving a DC component Idd included in the primary current I _1A of the transformer 1, and 55 integrates the DC component Idd derived by the DC component deriving unit 54. An integrator (integrating means) for outputting a saturation detection signal when the reference value is exceeded, 56
Is a DC component deriving unit (integrating means) for deriving a DC component Idd included in the secondary current I _2a of the transformer 1, 57 is an integrating unit for the DC component Idd derived by the DC component deriving unit 56,
An integrator (integrating means) that outputs a saturation detection signal when the integration result exceeds a reference value.
7 is an OR circuit (integrating means) that outputs a saturation detection signal to the inhibit 30 when at least one of the outputs 7 outputs a saturation detection signal.

In the seventh embodiment, the fundamental wave component Id0
When the ratio Idd / Id0 of the direct current component Idd to the reference ratio exceeds the reference ratio, it is determined that the CT2A or the like is in a saturated state and a saturation detection signal is output.
The DC component Idd included in the primary current I _1A or the like may be integrated, and if the integration result exceeds a reference value, it may be determined that the CT 2A or the like is in a saturated state.

That is, the DC component deriving unit 54 derives the DC component Idd included in the primary current I _1A of the transformer 1, and the DC component deriving unit 56 calculates the DC component Idd included in the secondary current I _2a of the transformer 1. The component Idd is derived. Then, the integrator 55 integrates the DC component Idd derived by the DC component deriving unit 54, and when the integration result exceeds a reference value, determines that the CT2A or the like is in a saturated state and outputs a saturation detection signal. The integrator 57 integrates the DC component Idd derived by the DC component deriver 56, and when the integration result exceeds a reference value, determines that the CT3a and the like are in a saturated state.
Outputs the saturation detection signal. And the OR circuit 58
When at least one of the integrator 55 and the integrator 57 outputs the saturation detection signal, the saturation detection signal is converted to the inhibit 3 signal.
Output to 0.

Thus, similar to the seventh embodiment,
This has the effect of reducing the malfunction rate in the in-rush state and reducing the malfunction rate in the event of an internal accident. Further, similarly to the seventh embodiment, even if the differential current Id cannot be detected, an effect of detecting a saturated state of the CT2A or the like can be obtained.

[0081]

As described above, according to the present invention, when the judgment result of the judging means is not in the inrush state, and when the integration result of the integrating means is equal to or less than the reference value, the ratio differential means When a trip signal is output, the transformer is disconnected from the power system, so that the malfunction rate during an inrush state can be reduced and the malfunction rate during an internal accident can be reduced. There is an effect that can be done.

According to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the integration result of the integrating means sets the reference value. Since the transformer is configured to be cut off from the power system even in the case of exceeding, there is an effect that the transformer can be reliably cut off from the power system when an internal accident occurs.

According to the present invention, when the DC component detected by the detecting means does not exceed the reference value for a predetermined period of time, when the ratio differential means outputs a trip signal, the transformer is disconnected from the power system. With this configuration, it is possible to reduce the malfunction rate in the in-rush state and to reduce the malfunction rate in the event of an internal accident.

According to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the DC component detected by the detection means is reduced. Even if it exceeds the reference value for a predetermined time,
Since the transformer is configured to be cut off from the power system, there is an effect that the transformer can be reliably cut off from the power system when an internal accident occurs.

According to the present invention, the determination result of the determination means indicates that there is no inrush state, and the ratio of the DC component to the fundamental wave component detected by the detection means does not exceed the reference ratio for a predetermined time. In this case, when the ratio differential means outputs a trip signal, the transformer is cut off from the power system, so that the malfunction rate in the in-rush state can be reduced and the error rate in the event of an internal accident can be reduced. There is an effect that the inoperative rate can be reduced.

According to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the fundamental wave component detected by the detection means is output. Even if the ratio of the DC component to the power supply exceeds the reference ratio for a predetermined time, the transformer is disconnected from the power system, so that when an internal accident occurs, the transformer can be reliably disconnected from the power system. effective.

According to the present invention, the result of the determination by the determination means indicates that the inrush state is not present, and the ratio of the second harmonic component to the fundamental wave component detected by the detection means is maintained at the reference ratio for a predetermined time. If the ratio does not exceed the ratio, when the ratio differential means outputs a trip signal, the transformer is cut off from the power system, so that the malfunction rate in the in-rush state can be reduced and an internal accident occurs. There is an effect that the false malfunction rate at the time can be reduced.

According to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the fundamental wave component detected by the detection means is output. Even when the ratio of the second harmonic component to the reference ratio exceeds the reference ratio for a predetermined time, the transformer is cut off from the power system.
There is an effect that the transformer can be reliably disconnected from the power system.

According to the present invention, when the determination result of the determination means indicates that the vehicle is not in the inrush state, and when the reduction rate detected by the detection means is smaller than the reference reduction rate, the ratio differential means outputs the trip signal. Is output, the transformer is cut off from the power system, so that the malfunction rate in the in-rush state can be reduced and the malfunction rate in the event of an internal accident can be reduced. is there.

According to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the decrease rate detected by the detection means is reduced. Since the transformer is configured to be cut off from the power system even when it is greater than the reference reduction rate, there is an effect that the transformer can be reliably cut off from the power system when an internal accident occurs.

According to this invention, when the result of the judgment by the judging means indicates that the inrush state is not established, and when the addition result of the adding means is equal to or smaller than the reference value, the ratio differential means outputs a trip signal. Since the transformer is configured to be cut off from the power system, it is possible to reduce the malfunction rate in the in-rush state and to reduce the malfunction rate in the event of an internal accident. Further, even if the differential current cannot be detected, there is an effect that the saturated state of CT can be detected.

According to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the addition result of the addition means sets the reference value. Since the transformer is configured to be cut off from the power system even in the case of exceeding, there is an effect that the transformer can be reliably cut off from the power system when an internal accident occurs.

According to the present invention, when the result of the determination by the determination means indicates that there is no inrush state, and when the ratio of the DC component to the fundamental wave component included in the added current is equal to or less than the reference ratio, the ratio differential When the means outputs a trip signal, the transformer is disconnected from the power system, so that the malfunction rate in the in-rush state can be reduced and the malfunction rate in the event of an internal accident can be reduced. There is an effect that can be. Further, even if the differential current cannot be detected, there is an effect that the saturated state of CT can be detected.

According to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the ratio differential means for the fundamental wave component included in the added current is output. Even if the ratio of the DC component exceeds the reference ratio, the transformer is cut off from the power system. Therefore, when an internal accident occurs, the transformer can be reliably cut off from the power system.

According to the present invention, when the determination result of the determination means indicates that there is no inrush state, and when the integration result of the DC component included in the input current or the output current is equal to or less than the reference value, the ratio differential When the means outputs a trip signal, the transformer is disconnected from the power system, so that the malfunction rate in the in-rush state can be reduced and the malfunction rate in the event of an internal accident can be reduced. There is an effect that can be. Further, even if the differential current cannot be detected, there is an effect that the saturated state of CT can be detected.

According to the present invention, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the DC current included in the input current or the output current is reduced. Even if the component integration result exceeds the reference value,
Since the transformer is configured to be cut off from the power system, there is an effect that the transformer can be reliably cut off from the power system when an internal accident occurs.

[Brief description of the drawings]

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

FIG. 2 is a waveform diagram showing waveforms of various signals.

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

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

FIG. 5 is a configuration diagram showing a ratio differential relay device according to Embodiment 4 of the present invention.

FIG. 6 is a configuration diagram showing a ratio differential relay device according to Embodiment 5 of the present invention.

FIG. 7 is a configuration diagram showing a ratio differential relay device according to Embodiment 6 of the present invention.

FIG. 8 is a system diagram showing a power system to which a ratio differential relay device according to Embodiment 6 of the present invention is applied.

FIG. 9 is a configuration diagram showing a ratio differential relay device according to Embodiment 7 of the present invention.

FIG. 10 is a configuration diagram showing a ratio differential relay device according to Embodiment 8 of the present invention.

FIG. 11 is a system diagram showing a power system to which a conventional ratio differential relay device is applied.

FIG. 12 is a configuration diagram showing a conventional ratio differential relay device.

FIG. 13 is a waveform chart showing waveforms of various signals.

[Explanation of symbols]

Reference Signs List 21 suppression current deriving device (current deriving device), 22 differential current deriving device (current deriving device), 23 ratio differential device (ratio differential device), 24 fundamental wave filter (determining device), 25
2nd harmonic filter (judgment means), 26 inrush judgment device (judgment means), 27, 31, 34, 37 AND circuit (cutoff means), 28 DC component derivation device (detection means,
Integrating means), 29, 55, 57 integrator (integrating means),
30, 33, 36 inhibit (blocking means), 32,
35, 38 OR circuit (cutoff means), 39 level detector (detection means), 40, 42, 44 timer (detection means), 41, 43, 51, 52 ratio detector (detection means), 45 reduction rate detection (Detection means), 46, 48
Adders (adding means), 47, 49 Level detectors (adding means), 50 OR circuit (adding means), 53 OR circuit (detecting means), 54, 56 DC component deriving device (integrating means), 58 logic Sum circuit (integration means).

Claims (16)

[Claims] 1. A current deriving means for deriving a suppression current and a differential current from an input / output current of a transformer, and a trip when a ratio of the differential current to the suppression current derived by the current derivation exceeds a reference level. A ratio differential means for outputting a signal; and a determination means for determining whether or not an inrush state is present based on a ratio of a second harmonic component to a fundamental wave component included in the differential current derived by the current derivation means. An integrating means for integrating a DC component included in the differential current derived by the current deriving means, and a determination result of the determining means is not in an inrush state, and the integration result of the integrating means is a reference value. In the following cases, the ratio differential relay device includes: a disconnection unit that disconnects the transformer from the power system when the ratio differential unit outputs a trip signal. 2. The method according to claim 1, wherein when a plurality of ratio differential means out of the ratio differential means connected to each phase of the transformer output a trip signal, the integration result of the integration means sets a reference value. 2. The ratio differential relay according to claim 1, wherein the transformer is disconnected from the power system even if the voltage exceeds the threshold. 3. A current deriving means for deriving a suppression current and a differential current from an input / output current of a transformer, and a trip when a ratio of the differential current to the suppression current derived by the current deriving means exceeds a reference level. A ratio differential means for outputting a signal; and a determination means for determining whether or not an inrush state is present based on a ratio of a second harmonic component to a fundamental wave component included in the differential current derived by the current derivation means. Detecting means for detecting a direct current component included in the differential current derived by the current deriving means; and indicating that the determination result of the determining means is not in an inrush state, and detecting the direct current component detected by the detecting means. If the ratio does not exceed the reference value for a predetermined period of time, the ratio differential means outputs a trip signal, and the ratio differential means includes a disconnection means for disconnecting the transformer from the power system. Relay device. 4. The shut-off means, when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, a DC component detected by the detection means. 4. The ratio differential relay according to claim 3, wherein the transformer is disconnected from the power system even if the voltage exceeds the reference value for a predetermined time. 5. A current deriving means for deriving a suppression current and a differential current from an input / output current of a transformer, and a trip when a ratio of the differential current to the suppression current derived by the current derivation exceeds a reference level. A ratio differential means for outputting a signal; and a determination means for determining whether or not an inrush state is present based on a ratio of a second harmonic component to a fundamental wave component included in the differential current derived by the current derivation means. Detecting means for detecting a ratio of a DC component to a fundamental wave component included in the differential current derived by the current deriving means,
If the determination result of the determination means indicates that the inrush state is not present, and if the ratio of the DC component to the fundamental wave component detected by the detection means does not exceed the reference ratio for a predetermined time, the ratio difference And a shut-off means for shutting off the transformer from the power system when the driving means outputs a trip signal. 6. When a plurality of ratio differential means out of the ratio differential means connected to each phase of the transformer output a trip signal, the cutoff means includes a fundamental wave component detected by the detection means. 6. The ratio differential relay device according to claim 5, wherein the transformer is cut off from the power system even when the ratio of the DC component to the current exceeds the reference ratio for a predetermined time. 7. A current deriving means for deriving a suppression current and a differential current from an input / output current of a transformer, and a trip when a ratio of the differential current to the suppression current derived by the current deriving means exceeds a reference level. A ratio differential means for outputting a signal; and a determination means for determining whether or not an inrush state is present based on a ratio of a second harmonic component to a fundamental wave component included in the differential current derived by the current derivation means. Detecting means for detecting the ratio of the second harmonic component to the fundamental wave component included in the differential current derived by the current deriving means, and indicating that the determination result of the determination means is not in an inrush state, If the ratio of the second harmonic component to the fundamental component detected by the detection means does not exceed the reference ratio for a predetermined time, the ratio differential means outputs a trip signal. Then, a ratio differential relay device including a disconnecting unit that disconnects the transformer from the power system. 8. When a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal, the cutoff means includes a fundamental wave component detected by the detection means. 8. The ratio differential relay according to claim 7, wherein the transformer is disconnected from the power system even when the ratio of the second harmonic component to the power exceeds the reference ratio for a predetermined time. 9. A current deriving means for deriving a suppression current and a differential current from an input / output current of a transformer, and a trip when a ratio of the differential current to the suppression current derived by the current deriving means exceeds a reference level. A ratio differential means for outputting a signal; and a determination means for determining whether or not an inrush state is present based on a ratio of a second harmonic component to a fundamental wave component included in the differential current derived by the current derivation means. Detecting means for detecting a reduction rate of a ratio of a second harmonic component to a fundamental wave component included in the differential current derived by the current deriving means, and a state that the determination result of the determining means is not in an inrush state. In addition, when the reduction rate detected by the detection means is smaller than the reference reduction rate, when the ratio differential means outputs a trip signal, the transformer disconnects the transformer from the power system. Ratio differential relay device provided with disconnection means. 10. When a plurality of ratio differential means out of the ratio differential means connected to each phase of the transformer output a trip signal, the cutoff means reduces the decrease rate detected by the detection means. 10. The ratio differential relay device according to claim 9, wherein the transformer is disconnected from the power system even when the ratio is greater than the reference reduction rate. 11. A current deriving means for deriving a suppression current and a differential current from an input / output current of a transformer, and a trip when a ratio of the differential current to the suppression current derived by the current deriving means exceeds a reference level. A ratio differential means for outputting a signal; and a determination means for determining whether or not an inrush state is present based on a ratio of a second harmonic component to a fundamental wave component included in the differential current derived by the current derivation means. Adding means for adding each phase current and zero-phase current of the transformer to each other, and indicating that the judgment result of the judging means is not in an inrush state, and when the adding result of the adding means is equal to or less than a reference value. And a disconnecting means for disconnecting the transformer from the power system when the ratio differential means outputs a trip signal. 12. When a plurality of ratio differential means out of the ratio differential means connected to each phase of the transformer output a trip signal, the cutoff means sets a reference value as an addition result of the addition means. 12. The ratio differential relay device according to claim 11, wherein the transformer is disconnected from the power system even if it exceeds. 13. A current deriving means for deriving a suppression current and a differential current from an input / output current of a transformer, and a trip when a ratio of the differential current to the suppression current derived by the current derivation exceeds a reference level. A ratio differential means for outputting a signal; and a determination means for determining whether or not an inrush state is present based on a ratio of a second harmonic component to a fundamental wave component included in the differential current derived by the current derivation means. Detecting means for adding each phase current and the zero-phase current of the transformer to each other and detecting a ratio of a DC component to a fundamental wave component included in the addition result, and that the determination result of the determination means is not in an inrush state. In addition, when the ratio of the DC component to the fundamental component detected by the detection means is equal to or less than the reference ratio, when the ratio differential means outputs a trip signal, the transformer is turned on. A ratio differential relay device comprising: a disconnection unit that disconnects from a power system. 14. The shutoff means includes a fundamental wave component detected by the detection means when a plurality of ratio differential means among the ratio differential means connected to each phase of the transformer output a trip signal. 14. The ratio differential relay according to claim 13, wherein the transformer is cut off from the power system even when the ratio of the DC component to the power exceeds the reference ratio. 15. A current deriving means for deriving a suppression current and a differential current from an input / output current of a transformer, and a trip when a ratio of the differential current to the suppression current derived by the current derivation exceeds a reference level. A ratio differential means for outputting a signal; and a determination means for determining whether or not an inrush state is present based on a ratio of a second harmonic component to a fundamental wave component included in the differential current derived by the current derivation means. An integrating means for integrating a DC component included in an input current or an output current of the transformer, and a case where the determination result of the determining means is not in an inrush state and the integration result of the integrating means is equal to or less than a reference value. And a shut-off means for shutting off the transformer from the power system when the ratio differential means outputs a trip signal. 16. When a plurality of ratio differential means out of the ratio differential means connected to each phase of the transformer output a trip signal, the cutoff means determines that the integration result of the integration means is a reference value. 16. The ratio differential relay according to claim 15, wherein the transformer is disconnected from the power system even if the voltage exceeds the threshold.