KR102672483B1 - Apparatus for detecting failure of power transformer and method thereof - Google Patents

Abstract

The present invention relates to a failure detection device for a power transformer, comprising: a current detection unit that detects the current in the primary and secondary windings of each phase of the power transformer; And calculate the primary and secondary current conversion ratios for each phase based on the detected current, compare them to see if they are the same within the error range, and calculate the current conversion ratio difference between the phases. If the current conversion ratio difference between the phases is more than a specified standard, a failure occurs. It includes a control unit that determines and performs the corresponding operation.

Description

Apparatus and method for detecting failure of power transformer {APPARATUS FOR DETECTING FAILURE OF POWER TRANSFORMER AND METHOD THEREOF}

The present invention relates to a failure detection device and method for a power transformer. More specifically, the present invention relates to a fault detection device and method for a power transformer. More specifically, the current changes due to a change in the winding impedance of the primary or secondary phase (A, B, C) where an interlayer short circuit of the winding occurs. It relates to a failure detection device and method for a power transformer that allows detecting the initial failure of the power transformer based on the principle that the first and second phase current conversion ratios (secondary current/primary current) are generated differently. .

In general, a power transformer is a main transformer that supplies power to a distribution transformer by stepping down extra-high voltage to high voltage, and is mainly used where a large capacity load is required. However, power transformers are not operated until a breakdown occurs because the ripple effect on the power system is very large when a breakdown occurs.

Currently, when a breakdown or abnormality occurs in a domestic power transformer, the manager checks it and performs maintenance or replacement depending on the condition.

For example, the transformer maintenance methods currently being implemented mainly include Time Based Maintenance (TBM) and Condition Based Maintenance (CBM).

The TBM is a method of performing maintenance according to a certain cycle.

This method is easy to access because maintenance needs to be performed at a set interval, but since it is performed regardless of the condition of the device, unnecessary maintenance costs may be incurred depending on the conditions.

In addition, the CBM is a method of performing maintenance according to the condition conditions of the device, analyzing the condition at the time of inspection and performing maintenance according to the results. Therefore, this CBM has limitations in predicting conditions and deriving trends to prevent failures through optimal maintenance or maintenance.

As described above, each conventional maintenance method has economic and efficiency limitations, and accordingly, by detecting the initial failure of the power transformer (i.e., early symptoms before conversion to failure), maintenance can be quickly implemented in response to this. This is a situation where technology is needed.

The background technology of the present invention is disclosed in Republic of Korea Patent No. 10-2181262 (registered on November 16, 2020, transformer diagnostic device).

According to one aspect of the present invention, the present invention was created to solve the above problem, and the current increases due to a change in the winding impedance of the primary or secondary phase (A, B, C) where an interlayer short circuit of the winding occurs. A failure detection device and method for a power transformer that allows detecting the initial failure of a power transformer based on the principle that the primary and secondary current conversion ratios (secondary current/primary current) between each phase are changed differently. The purpose is to provide.

A failure detection device for a power transformer according to one aspect of the present invention includes a current detection unit that detects current in the primary and secondary windings of each phase of the power transformer; And calculate the primary and secondary current conversion ratios for each phase based on the detected current, compare them to see if they are the same within the error range, and calculate the current conversion ratio difference between the phases. If the current conversion ratio difference between the phases is more than a specified standard, a failure occurs. It is characterized by including a control unit that determines and performs the corresponding operation.

In the present invention, the control unit calculates the A-B phase current conversion ratio difference by "[(A-phase current conversion ratio - B-phase current conversion ratio)/(A-phase current conversion ratio)]*100%", and " The B-C phase current conversion ratio difference is calculated by "[(B-phase current conversion ratio - C-phase current conversion ratio)/(B-phase current conversion ratio)]*100%", and "[(C-phase current conversion ratio - A phase It is characterized in that the C-A phase current conversion ratio difference is calculated by "current conversion ratio)/(C-phase current conversion ratio)]*100%".

In the present invention, the control unit calculates the primary and secondary current conversion ratio by “secondary current/primary current”.

In the present invention, when the power transformer is normal, the current conversion ratio between phases is the same within the error range, and when a short circuit between windings of the power transformer or a failure near the neutral point occurs, a difference occurs in the current conversion ratio between phases. It is characterized by

In the present invention, the control unit diagnoses that there is a possibility of an initial failure when the current conversion ratio difference between the phases exceeds a specified first standard and outputs an alarm, and when the current conversion ratio difference between the phases exceeds a specified second standard, the control unit diagnoses the possibility of an initial failure. It is characterized by diagnosing a fault, outputting an alarm, and separating relays or equipment.

A method for detecting a failure of a power transformer according to another aspect of the present invention includes the steps of a control unit detecting the current of the primary and secondary windings for each phase (A, B, C) of the power transformer through a current detection unit; The control unit calculates the primary and secondary current conversion ratios between each phase and compares whether they are the same within an error range; As a result of the comparison, if the primary and secondary current conversion ratios between each phase of the power transformer are not the same within the error range, calculating the current conversion ratio difference between the phases by the control unit; And the control unit checks whether the current conversion ratio difference between the phases is more than a specified standard, and if the current conversion ratio difference between the phases is more than the specified standard, determining a failure and performing a corresponding operation.

In the present invention, in the step of calculating the current conversion ratio difference between the phases, the control unit calculates "[(A-phase current conversion ratio - B-phase current conversion ratio)/(A-phase current conversion ratio)]*100%". Calculate the A-B phase current conversion ratio difference by "[(B-phase current conversion ratio - C-phase current conversion ratio)/(B-phase current conversion ratio)]*100%" to calculate the B-C phase current conversion ratio difference. , It is characterized in that the C-A phase current conversion ratio difference is calculated by "[(C-phase current conversion ratio - A-phase current conversion ratio)/(C-phase current conversion ratio)]*100%".

In the present invention, in the step of calculating the primary and secondary current conversion ratios, the control unit calculates the primary and secondary current conversion ratios by “secondary current/primary current”. do.

In the present invention, in the step of calculating the current conversion ratio and comparing whether they are the same within the error range, if the power transformer is normal, the interphase current conversion ratio is the same within the error range, and the power transformer When a winding short circuit or a fault near the neutral point occurs, a difference occurs in the current conversion ratio between phases.

In the present invention, in the step of performing the corresponding operation, the control unit generates an alarm when the current conversion ratio difference between phases is greater than the first standard and operates the relay when the current conversion ratio difference between phases is greater than the second standard. It is characterized by separating equipment.

According to one aspect of the present invention, the current changes due to a change in the winding impedance of the primary or secondary phase (A, B, C) in which an interlayer short circuit of the winding occurs, thereby changing the first and second current conversion ratios between each phase ( Based on the principle that secondary current/primary current) is generated differently, it is possible to detect the initial failure of the power transformer.

Figure 1 is an example diagram shown to explain a general transformer winding interlayer short circuit failure.
Figure 2 is an example diagram shown to explain a failure near the neutral point of a general transformer.
Figure 3 is an exemplary diagram showing a schematic configuration of a failure detection device for a power transformer according to an embodiment of the present invention.
FIG. 4 is an example diagram shown in FIG. 3 to explain a method of diagnosing an initial failure of a power transformer based on the phase-to-phase current conversion ratio.
Figure 5 is an example diagram shown in Figure 3 to explain a method of diagnosing an initial failure of a power transformer based on the current conversion ratio difference between phases.
Figure 6 is a flowchart illustrating a method for detecting a failure of a power transformer according to an embodiment of the present invention.

Hereinafter, an embodiment of an apparatus and method for detecting a fault in a power transformer according to the present invention will be described with reference to the attached drawings.

In this process, the thickness of lines or sizes of components shown in the drawing may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are terms defined in consideration of functions in the present invention, and may vary depending on the intention or custom of the user or operator. Therefore, definitions of these terms should be made based on the content throughout this specification.

Figure 1 is an example diagram shown to explain a general transformer winding interlayer short circuit failure. Here, interlayer short circuit means that when winding a winding (coil) on an iron core on the primary or secondary side of the transformer, not only one layer but several layers are wound. This means that the insulation between the lower and upper layers of the winding is destroyed, causing the coils to short-circuit each other. This inter-floor short circuit is one of the most common causes of fatal failures such as transformer explosion, winding or core deformation, and if not detected early, it can spread to adjacent windings and develop into a ground fault.

Figure 2 is an example diagram shown to explain a failure near the neutral point (Neutrall) of a general transformer. As each terminal (A, B, C) approaches the neutral point, the impedance increases (→fault current decreases), real system simulation test As a result, current differential relays currently in operation cannot detect faults when a fault occurs near the neutral point, fail when short-circuited at a distance of approximately 10% or less from the neutral point, and fail at a distance of approximately 30% or less from the neutral point when a ground fault occurs. There is.

The reason why it is impossible to detect the initial failure (internal failure) of a power transformer is because of the transformer protection device (i.e., a device that detects a failure in power equipment and isolates the relevant equipment from the system to prevent the failure from expanding). There is a reason.

For example, the transformer protection device includes an electrical protection device and a mechanical protection device, and the electrical protection device (e.g., current differential relay, overcurrent relay) operates depending on the size of the current generated in the event of a fault, such as a short circuit between windings and near the neutral point. Due to the nature of the fault, the fault current is very small, making it difficult to detect the fault that initially occurred at the relay operation setting value. In addition, the operation of the mechanical protection device is determined depending on the location and severity of the internal fault of the transformer. However, due to the nature of the initial inter-layer short circuit and the fault near the neutral point, the internal pressure rise is small, making it difficult to detect the fault.

Hereinafter, a fault detection device for a power transformer according to this embodiment will be described with reference to FIGS. 3 to 6. At this time, the failure detection device for the power transformer according to this embodiment may be implemented by adding functions to the existing electrical protection device.

Figure 3 is an exemplary diagram showing the schematic configuration of a failure detection device for a power transformer according to an embodiment of the present invention.

As shown in FIG. 3, the failure detection device for a power transformer according to this embodiment includes a current detection unit 110, a control unit 120, and an alarm output unit 130.

The current detection unit 110 detects the primary and secondary currents for each phase (A, B, C) of the power transformer.

The control unit 120 determines the primary and secondary current conversion ratio (secondary current/1) between each phase according to the current that changes according to the winding impedance change for each phase (A, B, C) of the primary and secondary windings. Calculate the secondary side current).

In addition, the control unit 120 compares whether the primary and secondary current conversion ratios (secondary current/primary current) between each phase are the same within the error range, and based on the results of this comparison, the power transformer Diagnose early faults.

For example, as shown in FIG. 4, when an interlayer short circuit occurs in the primary or secondary winding of either phase of a power transformer, the current changes due to a change in the winding impedance of the corresponding phase, resulting in primary and secondary currents between each phase. The conversion ratio (secondary side current/primary side current) becomes different. If the power transformer is normal, the current conversion ratio may change somewhat, but the current conversion ratio between phases must be the same within the error range.

4 is an example diagram shown in FIG. 3 to explain a method of diagnosing an initial failure of a power transformer based on the current conversion ratio between phases. As shown, when the power transformer is normal, the phase-to-phase current The conversion ratio is the same within the error range, but when a short circuit between windings of a power transformer (or a fault near the neutral point) occurs, a difference occurs in the current conversion ratio between phases.

In addition, the control unit 120 constantly monitors the primary and secondary current values of each phase of the power transformer to calculate the current conversion ratio difference between phases, and diagnoses the initial failure of the power transformer based on this calculation result.

For example, the current conversion ratio difference between phases (example of A-B phase) is "[(A-phase current conversion ratio - B-phase current conversion ratio)/(A-phase current conversion ratio)]*100%", and the inter-phase current conversion ratio difference (B-C phase) Example) is "[(B-phase current conversion ratio - C-phase current conversion ratio)/(B-phase current conversion ratio)]*100%", and current conversion ratio difference between phases (C-A phase example) is "[(C-phase current Conversion ratio - A-phase current conversion ratio)/(C-phase current conversion ratio)]*100%".

In addition, the control unit 120 diagnoses that there is a possibility of an initial failure when the current conversion ratio difference between the phases exceeds a specified first standard (e.g., ±5% or more) and outputs an alarm, and outputs an alarm when the current conversion ratio difference between the phases is specified. 2 If it exceeds the standard (e.g. ±10% or more), it is diagnosed as an initial failure and an alarm is output (or a relay or equipment separation is activated) (see Figure 5).

5 is an example diagram shown in FIG. 3 to explain a method of diagnosing an initial failure of a power transformer based on the current conversion ratio difference between phases. As shown, the current conversion ratio difference between phases of A-B is If it is above the 1 standard (e.g., ±5% or more), an alarm is generated, and if the current conversion ratio difference between phases on A-B is more than the second standard (e.g., ±10% or more), operate the relay or disconnect the equipment. .

The alarm output unit 130 outputs a designated alarm when diagnosing an initial failure of the power transformer under the control of the control unit 120.

Figure 6 is a flowchart illustrating a method for detecting a failure of a power transformer according to an embodiment of the present invention.

Referring to FIG. 6, the control unit 120 detects the primary and secondary currents for each phase (A, B, and C) of the power transformer through the current detection unit 110 (S101).

In addition, the control unit 120 calculates the primary and secondary current conversion ratio (secondary current/primary current) between each phase, so that the primary and secondary current conversion ratio (secondary current/primary current) between each phase is Compare whether they are identical within the error range (S102).

For example, when the power transformer is normal, the current conversion ratio between phases is the same within the error range, but when a short circuit between windings of the power transformer (or a fault near the neutral point) occurs, there is a difference in the current conversion ratio between phases.

Therefore, as a result of the comparison (S102), if the primary and secondary current conversion ratios (secondary current / primary current) between each phase of the power transformer are not the same within the error range (example of S102), the control unit (120) calculates the current conversion ratio difference between phases (S103).

For example, the current conversion ratio difference between phases (example of A-B phase) is "[(A-phase current conversion ratio - B-phase current conversion ratio)/(A-phase current conversion ratio)]*100%", and the inter-phase current conversion ratio difference (B-C phase) Example) is "[(B-phase current conversion ratio - C-phase current conversion ratio)/(B-phase current conversion ratio)]*100%", and current conversion ratio difference between phases (C-A phase example) is "[(C-phase current Conversion ratio - A-phase current conversion ratio)/(C-phase current conversion ratio)]*100%".

Additionally, the control unit 120 checks whether the current conversion ratio difference between phases is greater than a specified standard (S104).

As a result of the check (S104), if the current conversion ratio difference between phases occurs more than the first standard (e.g., ±5% or more) or more than the second standard (e.g., ±10% or more) (example of S104), the control unit 120 ) determines that there is a possibility of an initial failure (or an initial failure) of the power transformer and performs a designated failure response operation (S105).

For example, if the current conversion ratio difference between phases is more than the first standard (e.g., ±5% or more), an alarm is generated, and if the current conversion ratio difference between phases is more than the second standard (e.g., ±10% or more), the relay is activated. Or disconnect the equipment.

As described above, in this embodiment, as the current changes due to a change in the winding impedance of the primary or secondary phase (A, B, C) in which an interlayer short circuit of the winding of the power transformer occurs, the first and second current conversion ratios between each phase Based on the principle that (secondary side current/primary side current) is generated differently, the initial failure of the power transformer can be detected, resulting in interlayer short circuit failure of the winding compared to the existing protection devices (electrical and mechanical protection devices) of the power transformer. It is effective in preventing the expansion of equipment failure in advance by sensitively detecting the initial state of failure near the neutral point.

In addition, this embodiment has the effect of reducing repair costs by detecting and responding to (repairing) inter-layer short circuits and faults near the neutral point of the power transformer winding at an early stage.

In addition, this embodiment has the effect of preventing fires in transformers that may occur due to expansion of failures due to non-detection of initial internal failures of power transformers and blocking power supply disruptions and civil complaints due to long-term power outages due to facility fires. .

As described above, the present invention has been described with reference to the embodiments shown in the drawings, but these are merely illustrative, and various modifications and equivalent embodiments can be made by those skilled in the art. You will understand the point. Therefore, the scope of technical protection of the present invention should be determined by the scope of the patent claims below. Implementations described herein may also be implemented as, for example, a method or process, device, software program, data stream, or signal. Although discussed only in the context of a single form of implementation (eg, only as a method), implementations of the features discussed may also be implemented in other forms (eg, devices or programs). The device may be implemented with appropriate hardware, software, firmware, etc. The method may be implemented in a device such as a processor, which generally refers to a processing device that includes a computer, microprocessor, integrated circuit, or programmable logic device. Processors also include communication devices such as computers, cell phones, portable/personal digital assistants (“PDAs”) and other devices that facilitate communication of information between end-users.

110: current detection unit
120: control unit
130: Alarm output unit

Claims (10)

A current detection unit that detects the current in the primary and secondary windings of each phase of the power transformer; and
Calculate the primary and secondary current conversion ratios for each phase based on the detected current, compare them to see if they are the same within the error range, and calculate the current conversion ratio difference between phases. If the current conversion ratio difference between phases is greater than the specified standard, it is a failure. Includes a control unit that makes judgments and performs corresponding actions,
The control unit,
If the current conversion ratio difference between the phases exceeds a specified first standard, it is diagnosed that there is a possibility of an initial failure and an alarm is output,
A failure detection device for a power transformer, characterized in that when the current conversion ratio difference between the phases occurs more than a specified second standard, it is diagnosed as an initial failure, outputs an alarm, and separates the relay or equipment.
The method of claim 1, wherein the control unit:
Calculate the AB-phase current conversion ratio difference by "[(A-phase current conversion ratio - B-phase current conversion ratio)/(A-phase current conversion ratio)]*100%",
The BC phase current conversion ratio difference is calculated by "[(B-phase current conversion ratio - C-phase current conversion ratio)/(B-phase current conversion ratio)]*100%",
A fault detection device for a power transformer, characterized in that it calculates the CA-phase current conversion ratio difference by "[(C-phase current conversion ratio - A-phase current conversion ratio)/(C-phase current conversion ratio)]*100%" .
The method of claim 1, wherein the control unit:
A fault detection device for a power transformer, characterized in that the primary and secondary current conversion ratio is calculated by “secondary side current/primary side current”.
According to clause 1,
When the power transformer is normal, the current conversion ratio between phases is the same within the error range,
A fault detection device for a power transformer, wherein a difference occurs in the current conversion ratio between phases when a winding short circuit or a fault near the neutral point of the power transformer occurs.
delete A control unit detecting the current of the primary and secondary windings for each phase (A, B, C) of the power transformer through a current detection unit;
The control unit calculates the primary and secondary current conversion ratios between each phase and compares whether they are the same within an error range;
As a result of the comparison, if the primary and secondary current conversion ratios between each phase of the power transformer are not the same within the error range, calculating the current conversion ratio difference between the phases by the control unit; and
The control unit checks whether the current conversion ratio difference between phases is more than a specified standard, and if the current conversion ratio difference between phases is more than a specified standard, determining a failure and performing a corresponding operation;
In the step of determining a failure and performing a corresponding operation if the current conversion ratio difference between the phases is greater than a specified standard,
The control unit,
If the current conversion ratio difference between the phases exceeds a specified first standard, it is diagnosed that there is a possibility of an initial failure and an alarm is output,
A fault detection method for a power transformer, characterized in that when the current conversion ratio difference between the phases exceeds a specified second standard, it is diagnosed as an initial fault, an alarm is output, and a relay or equipment is separated.
The method of claim 6, wherein in calculating the current conversion ratio difference between phases,
The control unit,
Calculate the AB-phase current conversion ratio difference by "[(A-phase current conversion ratio - B-phase current conversion ratio)/(A-phase current conversion ratio)]*100%",
The BC phase current conversion ratio difference is calculated by "[(B-phase current conversion ratio - C-phase current conversion ratio)/(B-phase current conversion ratio)]*100%",
A fault detection method for a power transformer, characterized in that the CA-phase current conversion ratio difference is calculated by "[(C-phase current conversion ratio - A-phase current conversion ratio)/(C-phase current conversion ratio)]*100%" .
The method of claim 6, wherein in calculating the primary and secondary current conversion ratios,
The control unit,
A fault detection method for a power transformer, characterized in that the primary and secondary current conversion ratio is calculated by “secondary side current/primary side current”.
The method of claim 6, wherein in calculating the current conversion ratios and comparing whether they are the same within an error range,
When the power transformer is normal, the current conversion ratio between phases is the same within the error range, and when a short circuit between windings of the power transformer or a failure near the neutral point occurs, a difference occurs in the current conversion ratio between phases. Method for detecting faults in power transformers.
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