KR20160047208A - Apparatus and method for detecting internal fault of transformer - Google Patents

Abstract

The present invention relates to an apparatus and method for detecting an internal fault of a transformer, and more particularly, to a transformer internal fault detecting apparatus and method, which are capable of detecting a first leakage current and a second leakage current input from a current transformer (CT) provided on a primary winding side and a secondary winding side, A detecting unit for detecting the signal; A setting unit for setting an instantaneous current and a lean current for the detected first leakage current and the second leakage current; An operation determining unit for determining an instantaneous operation of the first leakage current or the second leakage current set to the instantaneous operation or the instantaneous current of the first leakage current or the second leakage current set to the instantaneous current; And a failure detector for detecting whether the transformer is on the primary winding side or the secondary winding side based on the determination result.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a transformer internal fault detection apparatus,

The present invention relates to an apparatus and method for detecting an internal fault in a transformer, and more particularly, to a system and method for detecting a fault in a transformer, including a first leakage current input from a current transformer (CT) provided on a primary winding side and a secondary winding side of a transformer, The present invention relates to an apparatus for detecting an internal fault in a transformer and a method for detecting an internal fault by detecting a leakage current.

The power system is divided into a dendrite system, a loop system, and a network system. Domestic transmission system is composed of network type. Most of the power distribution system uses open-loop at all times and closed-loop method is used only in some areas. However, the low-voltage system still uses the dendritic system, and the dendritic system distributes power to a large number of low-capacity transformers. Therefore, the utilization rate of the transformer is low, a power failure occurs when the transformer is replaced, There was a problem. Especially, it is necessary to prepare for large capacity transformer operation, distributed power supply linkage, increase of electric car charging station demand and space shortage of ground equipment installation due to the change of capacity of low pressure supply contract (149kW → 499kW). In order to cope with such problems and increase the demand for high quality electric power supply, it is possible to suppress the expansion of facilities by increasing the utilization ratio of the transformer by operating the transformer operated by the conventional dendritic method in parallel with the loop type system, Improvement in reliability of supply due to replacement and reduction of voltage fluctuation, and increase in demand for electric vehicle charging stations.

In particular, if a transformer internal fault occurs when a transformer is operated in parallel in a loop system, the faulty transformer must be quickly disconnected from the system to prevent failure in the sound field by determining the internal fault or external fault factor of the transformer. Also, it is necessary to develop a new protection device that can judge the internal fault of the transformer in the low capacity transformer from the viewpoint of economical efficiency and reliability when the low capacity transformer is operated in a large amount in the loop operation.

Recently, electric power consumption has been rapidly increasing due to the increase of electric power utilization facilities and convenience facilities such as cooling load and computers. This phenomenon is caused by the expansion of the overloaded area and the load intensified area.

As a result, the load applied by the transformer located at the end of the system is increased irregularly, and frequent insulation breakdown occurs in the transformer due to deterioration due to the overload phenomenon and deterioration due to the external environment.

Transformers play an important role in providing a stable supply of power, which requires higher reliability than any other power facility. Therefore, it is urgently required to develop a new fault diagnosis method for detecting and resolving the abnormality of the transformer in order to prevent the accident of the transformer in advance.

Therefore, recently, a transformer is provided with a ratio differential protection relay as disclosed in Korean Patent Publication No. 1993-024243 for protecting the transformer. This is a method to detect the internal fault and external fault of the transformer using the current flowing in the primary side winding and the secondary side winding of the transformer. However, this method has a problem in that the installation method is complicated, and it is expensive and mainly used only for a large-sized transformer. In particular, in the case of transformers for low-voltage loops, high-voltage circuit breakers on the primary side and low-voltage circuit breakers on the secondary side of the transformer are used, and the CT saturation characteristics are different for each circuit breaker maker, and the distance between the primary- It is difficult to connect the current transformer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a transformer, which detects a first leakage current and a second leakage current inputted from a current transformer provided respectively on a primary winding side and a secondary winding side of a transformer, The present invention provides an apparatus for detecting an internal fault of a transformer and a method for detecting an internal fault by determining an instantaneous operation or a temporary operation of a leakage current and a second leakage current.

According to an aspect of the present invention, there is provided an apparatus for detecting an internal fault in a transformer, comprising: a first leakage current and a second leakage current from a current transformer (CT) provided on a primary winding side and a secondary winding side of a transformer, A detector for detecting a current; A setting unit for setting an instantaneous current and a lean current for the detected first leakage current and the second leakage current; An operation determining unit for determining an instantaneous operation of the first leakage current or the second leakage current set to the instantaneous operation or the instantaneous current of the first leakage current or the second leakage current set to the instantaneous current; And a failure detection unit for detecting an internal failure of the transformer based on the determination result.

The detector may further include: a first leakage current detector for detecting a first leakage current; And a second leakage current detector for detecting a second leakage current.

The detection unit may convert the fundamental wave component into a voltage value through the correction resistances of the detected first leakage current and second leakage current and then convert the extracted fundamental wave component into an analog signal to an analog signal to-digital converter).

Also, the operation determining unit may include: an instantaneous operation determining unit that determines an instantaneous operation according to a magnitude of a first leakage current or a second leakage current set at an instantaneous current; And a temporal-operation determining unit for determining a temporal operation based on the magnitude and the duration of the first leakage current or the second leakage current set to the instantaneous current.

In addition, the instantaneous operation determining unit determines that the instantaneous operation is performed when the magnitude of the first leakage current or the second leakage current set to the instantaneous current is greater than a predetermined set current.

Also, the instantaneous operation determination unit determines that the second leakage current is a one-time operation when the magnitude of the second leakage current is greater than a preset current for a predetermined period of time.

In addition, the instantaneous operation determination unit may be configured to set the instantaneous operation return time.

If the determined instantaneous operation or the transient operation is equal to or greater than a predetermined number of operations, the failure detection unit may determine whether a primary winding-side internal fault or a secondary-side internal fault is detected based on a first leakage current or a second leakage current set at the instantaneous current or the instantaneous current, And the internal fault of the winding is discriminated and detected.

In addition, the failure detecting unit controls the operation of the alarm contact and the trip contact according to the accumulated instantaneous operation or the temporary operation.

According to an aspect of the present invention, there is provided a method for detecting an internal fault in a transformer, the method including detecting a first leakage current And detecting a second leakage current; Setting the instantaneous current and the instantaneous current for the detected first leakage current and the second leakage current by the setting unit; Determining an instantaneous operation of the first leakage current or the second leakage current set at the instantaneous current or a instantaneous operation of the first leakage current or the second leakage current set at the instantaneous current by the operation determination unit; And detecting an internal failure of the transformer based on the determination result by the failure detection unit.

The step of detecting the first leakage current and the second leakage current inputted from the current transformers provided respectively on the primary winding side and the secondary winding side of the transformer may include detecting a correction resistance of the detected first leakage current and the second leakage current, And then extracts the fundamental wave component, and converts the extracted fundamental wave component from an analog signal to an analog signal (ADC).

The step of determining the instantaneous operation of the first leakage current or the second leakage current set at the instantaneous current or the instantaneous operation of the first leakage current or the second leakage current set at the instantaneous current may include determining a first leakage current Determining an instantaneous operation according to a case where a magnitude of a second leakage current is larger than a predetermined set current; And determining a transient operation according to a case where a magnitude of a first leakage current or a second leakage current set at a time current is greater than a predetermined set current and continues for a predetermined time.

The step of discriminating and detecting whether a primary winding side fault or a secondary winding side fault of the transformer is based on the result of the judgment is characterized in that if the determined instantaneous operation or temporal operation is equal to or greater than a preset number of operations, Side internal-fault or secondary-winding-side internal fault based on a first leakage current or a second leakage current set to the first coil side or the second coil side.

The step of discriminating and detecting whether the primary winding side fault or the secondary winding side fault of the transformer is based on the judgment result is characterized in that the operation of the alarm contact and the trip contact is controlled in accordance with the accumulated instantaneous operation or the temporary operation do.

An apparatus and method for detecting an internal breakdown of a transformer according to the present invention having the above-described configuration detects a first leakage current and a second leakage current inputted from a current transformer provided respectively on a primary winding side and a secondary winding side of a transformer , The instantaneous current or the instantaneous current for the detected first leakage current and the second leakage current is set and then the instantaneous operation or the instantaneous operation is determined to detect whether the primary fault is on the secondary side or the secondary fault on the secondary side , It is possible to accurately detect the internal fault of the transformer using only the leakage current without being influenced by the saturation characteristic of the current transformer.

1 is a diagram illustrating a system configuration diagram of a transformer and a transformer internal fault detection apparatus according to the present invention.
2 is a diagram for explaining a detailed configuration of a transformer internal fault detecting apparatus according to the present invention.
3 is a diagram for explaining leakage current detection in the event of an external failure of the transformer according to the present invention.
4 is a diagram for explaining leakage current detection in an internal failure of a transformer according to the present invention.
5 is a diagram for explaining a procedure of a transformer internal fault detection method according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate a person skilled in the art to easily carry out the technical idea of the present invention. . First, in adding reference numerals to the constituent elements of the drawings, it should be noted that the same constituent elements are denoted by the same reference numerals whenever possible even if they are displayed on other drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a transformer internal fault detection apparatus and method according to an embodiment of the present invention will be described in detail.

1 is a diagram illustrating a system configuration diagram of a transformer and a transformer internal fault detection apparatus according to the present invention.

1, a transformer according to the present invention is a low-voltage loop type transformer having a Δ wiring and a Y wiring. The transformer is connected to the primary winding side and the secondary winding side by a current transformer , 10 and 20, respectively.

In consideration of the characteristics of the transformer constructed as described above, the transformer internal fault detection apparatus 100 according to the present invention detects a leakage current at the time of an internal failure of the transformer and prevents a leakage current at the time of an external failure, Can be detected.

2 is a diagram for explaining a detailed configuration of a transformer internal fault detecting apparatus according to the present invention.

The transformer internal fault detection apparatus 100 according to the present invention includes a detection unit 110, a setting unit 120, an operation determination unit 130, and a failure detection unit 140.

The detection unit 110 detects a first leakage current and a second leakage current that are input from the current transformers provided respectively on the primary winding side and the secondary winding side of the transformer.

The detection unit 110 includes a first leakage current detection unit 110a for detecting a first leakage current and a second leakage current detection unit 110b for detecting a second leakage current.

The detection unit 110 converts a fundamental wave component into a voltage value through a correction resistance of the detected first leakage current and a second leakage current and converts the extracted fundamental wave component from an analog signal to a digital signal -to-digital converter). That is, the detection unit 110 detects only fundamental wave components to prevent malfunction due to disturbances such as harmonics and surges, filters out the remaining components, and converts the analog signals into digital signals.

The setting unit 120 sets the instantaneous current and the instantaneous current for the detected first leakage current and the second leakage current.

The operation determining unit 130 determines the instantaneous operation of the first leakage current or the second leakage current set at the instantaneous current or the instantaneous operation of the first leakage current or the second leakage current set at the instantaneous current. In this case, the instantaneous state means a protection operation which operates in a very short time when the abnormal current is detected, and the protection operation which operates after a certain time after detecting the abnormal current.

For this, the operation determination unit 130 includes an instantaneous operation determination unit 130a and a temporal operation determination unit 130b.

The instantaneous operation determination unit 130a determines instantaneous operation according to the magnitude of the first leakage current or the second leakage current set at the instantaneous current.

The instantaneous operation determination unit 130a determines that the instantaneous operation is performed when the magnitude of the first leakage current or the second leakage current set at the instantaneous current is greater than a predetermined set current.

The temporal operation determination unit 130b determines the temporal operation according to the magnitude and duration of the first leakage current or the second leakage current set at the instantaneous current.

The instantaneous operation determination unit 130b determines that the second leakage current is a one-time operation when the magnitude of the second leakage current is greater than a predetermined set current and lasts for a predetermined time. At this time, the time limit operation return time is also set in advance.

In more detail, the temporal-motion determining unit 130b is calculated using a time-setting value and a judgment function for the time-instant return value according to the following expressions (1) and (2). At this time, the time setting value is calculated by the operation time is inverse according to the pickup multiples (detection current / set current) (the characteristic that operates at a short time as the input becomes bigger), and the setting time can be set from 0 to 10 seconds . Also, the return time can be set to 0 to 60 seconds.

[Equation 1]

[Equation 2]

※ M (Pickup Multiplier), TD (Time Dial), A, B, K, p: Setting Constant

Rt (Reset Time [Sec], q: Constant)

The failure detection unit 140 detects whether an internal failure of the transformer, that is, an internal failure on the primary winding side or an internal failure on the secondary winding side, is detected based on the determination result.

If the detected instantaneous operation or the transient operation is equal to or greater than the preset number of operations, the fault detector 140 detects whether the current transformer that detects the first leakage current or the second leakage current set to the instantaneous current or the instantaneous current is the primary winding side The detection of the internal fault on the primary winding side or the internal fault on the secondary winding side is discriminated and detected.

The failure detection unit 140 controls the operation of the alarm contact 30 and the trip contact 40 according to the accumulated instantaneous operation or the temporary operation.

3 is a diagram for explaining leakage current detection in the event of an external failure of the transformer according to the present invention.

3, when 6 to 7 distribution lines are drawn out from one main transformer of the substation, and the ground fault failure (high advantage) occurs on the power line side among the various lines, the transformer is connected in △ connection, The leakage current is not detected by the first leakage current detecting unit 11 of the first embodiment. Further, when the ground fault of the secondary winding of the transformer fails, the C phase and the N phase of the secondary winding side alternator 20 detect the ground fault current and are canceled each other so that the leakage current is not detected in the second leakage current detecting unit 21, It is possible to prevent malfunction of protective relay in case of external fault.

4 is a diagram for explaining leakage current detection in an internal failure of a transformer according to the present invention.

Referring to FIG. 4, when the primary winding side coil of the transformer is grounded by an insulation failure, a leakage current is generated. The leakage current is detected in the first leakage current detector 11 of the transformer 10 on the primary winding side of the transformer so that the protection relay operates normally.

Further, when the secondary winding side coil of the Y-connected transformer is grounded due to the winding failure, the second leakage current detecting portion 21 of the secondary winding side current transformer 20 of the transformer detects the leakage current. At this time, when the ground fault of the secondary side of the transformer occurs, the secondary neutral point of the transformer should be pulled out without being grounded in the transformer so as to prevent the leakage current from operating due to the leakage current, and ground 23 at the secondary side of the neutral line current transformer.

5 is a diagram for explaining a procedure of a transformer internal fault detection method according to the present invention.

Referring to FIG. 5, the transformer internal fault detection method according to the present invention uses a transformer internal fault detection device as described above, and a duplicate description will be omitted.

First, a first leakage current and a second leakage current inputted from a current transformer provided on the primary winding side and the secondary winding side of the transformer are detected by the detection unit (S100). In step S100, the voltage is converted into a voltage value through the correction resistances of the first leakage current and the second leakage current, and then the fundamental wave component is extracted, and the extracted fundamental wave component is converted from an analog signal to a digital signal.

Next, the setting unit sets the instantaneous current and the instantaneous current for the detected first leakage current and the second leakage current (S200).

Next, the operation determining unit determines the instantaneous operation of the first leakage current or the second leakage current set at the instantaneous current or the instantaneous operation of the first leakage current or the second leakage current set at the instantaneous current (S300). In operation S310, it is determined whether the first leakage current or the second leakage current is larger than a preset current in step S310. If the first leakage current or the second leakage current (Step S320). The time constant is determined according to the case where the magnitude of the current is greater than the preset current for a predetermined period of time.

Next, the failure detection unit detects an internal failure of the transformer based on the determination result (S400). If it is determined that the instantaneous operation or the transient operation is equal to or greater than the preset number of operations, it is determined whether the first or second leakage current is a primary or secondary leakage current based on the instantaneous current or the instantaneous current, And the operation of the alarm contact and the trip contact is controlled according to the accumulated instantaneous operation or the temporary operation.

As described above, according to the present invention, an apparatus for detecting an internal fault in a transformer detects a first leakage current and a second leakage current inputted from a current transformer provided on a primary winding side and a secondary winding side of a transformer, The instantaneous operation or the instantaneous operation is judged after setting the instantaneous current and the instantaneous current for the first leakage current and the second leakage current and by detecting whether the failure occurs on the primary winding side or the secondary winding side, The internal fault of the transformer can be accurately detected using only the leakage current without being influenced.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but many variations and modifications may be made without departing from the scope of the present invention. It will be understood that the invention may be practiced.

10, 20: Current transformer
100: Transformer internal fault detection device
110:
120: Setting section
130:
140:

Claims (12)

A detector for detecting a first leakage current and a second leakage current inputted from a current transformer (CT) provided on the primary winding side and the secondary winding side of the transformer;
A setting unit for setting an instantaneous current and a lean current for the detected first leakage current and the second leakage current;
An operation determining unit for determining an instantaneous operation of the first leakage current or the second leakage current set to the instantaneous operation or the instantaneous current of the first leakage current or the second leakage current set to the instantaneous current; And
A fault detection unit for detecting an internal fault of the transformer based on the determination result;
Wherein the transformer internal fault detection device comprises: The method according to claim 1,
The detection unit
A first leakage current detector for detecting a first leakage current; And
A second leakage current detector for detecting a second leakage current;
Wherein the transformer internal fault detection device comprises: The method according to claim 1,
The detection unit converts the detected fundamental leakage current and the second leakage current into a voltage value and then extracts the fundamental wave component and converts the extracted fundamental wave component from an analog signal to an analog signal a digital converter). The method according to claim 1,
Wherein,
An instantaneous operation determiner for determining an instantaneous operation according to a magnitude of a first leakage current or a second leakage current set to an instantaneous current; And
An instantaneous operation judging unit for judging a temporary operation according to the magnitude and the duration of the first leakage current or the second leakage current set to the instantaneous current;
Wherein the transformer internal fault detection device comprises: 5. The method of claim 4,
Wherein the instantaneous operation determining unit determines that the instantaneous operation is an operation when the magnitude of the first leakage current or the second leakage current set to the instantaneous current is greater than a predetermined set current. 5. The method of claim 4,
Wherein the instantaneous operation determination unit determines that the second leakage current is a one-time operation when the magnitude of the second leakage current is greater than a preset current for a predetermined period of time. The method according to claim 6,
Wherein the instantaneous operation judging unit sets the instantaneous operation return time to a predetermined value. The method according to claim 1,
The failure detecting unit determines whether the instantaneous operation or the transient operation is equal to or greater than a preset number of times based on a first leakage current or a second leakage current set at the instantaneous current or the instantaneous current, And the internal fault is detected by detecting whether or not the internal fault is detected. 9. The method of claim 8,
Wherein the fault detection unit controls the operation of the alarm contact and the trip contact according to the accumulated instantaneous operation or the instantaneous operation. Detecting a first leakage current and a second leakage current inputted from a current transformer (CT) provided on the primary winding side and the secondary winding side of the transformer by the detecting unit;
Setting the instantaneous current and the instantaneous current for the detected first leakage current and the second leakage current by the setting unit;
Determining an instantaneous operation of the first leakage current or the second leakage current set at the instantaneous current or a instantaneous operation of the first leakage current or the second leakage current set at the instantaneous current by the operation determination unit; And
Detecting an internal failure of the transformer based on the determination result by the failure detection unit;
And detecting the internal fault of the transformer. 11. The method of claim 10,
Determining the instantaneous operation of the first leakage current or the second leakage current set to the instantaneous current or the instantaneous operation of the first leakage current or the second leakage current set to the instantaneous current,
Determining an instantaneous operation according to a case where a magnitude of a first leakage current or a second leakage current set to an instantaneous current is greater than a predetermined set current; And
Determining a transient operation according to a case where a magnitude of a first leakage current or a second leakage current set to a transient current is greater than a predetermined set current and continues for a predetermined time;
And detecting the internal fault of the transformer. 11. The method of claim 10,
The step of detecting an internal fault of the transformer based on the determination result includes:
If it is judged that the instantaneous operation or the transient operation is equal to or greater than the preset number of operations, it is determined whether the primary or secondary leakage current is the primary or secondary leakage current based on the corresponding first instantaneous current or the first leakage current or the second leakage current And detecting the internal fault of the transformer.

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