KR101308054B1 - System and method for detecting ground fault using voltage regulation and harmonic analysis - Google Patents

Abstract

PURPOSE: A system and a method for detecting ground faults using a voltage regulation and a harmonic analysis are provided to determine the ground faults by analyzing a harmonic rate of voltage. CONSTITUTION: A system for detecting ground faults comprises a voltage measuring part, a calculating part (200), a fault signal outputting part, and a relay part. The voltage measuring part measures a potential difference and a voltage regulation between a rail and the ground based on inputted voltage. The calculating part determines the ground faults through the voltage regulation measured by the voltage measuring part and a harmonic analysis of the voltage. The calculating part comprises a first fault determining part (210) and a second fault determining part (220). The first fault determining part determines whether or not the voltage regulation measured by the voltage measuring part is abnormal. The second fault determining part detects a harmonic rate of the voltage measured by the voltage measuring part to determine whether or not the harmonic rate is abnormal. The fault signal outputting part outputs fault signals when the calculating part determines the ground faults. The relay part is operated after being delayed for a preset time according to the control of the calculating part. [Reference numerals] (200) Calculating part; (210) First fault determining part; (220) Second fault determining part; (AA) Fault signal output unit; (BB) Voltage measuring unit; (CC) Setting unit

Description

Ground fault detection system using voltage fluctuation rate and harmonic analysis and its method {SYSTEM AND METHOD FOR DETECTING GROUND FAULT USING VOLTAGE REGULATION AND HARMONIC ANALYSIS}

The present invention relates to a ground fault detection system and a method thereof, and more particularly, to determine ground fault based on a voltage variation rate as well as a potential difference between a rail and a ground, and at the same time, to analyze a ratio of harmonic components of a voltage, thereby providing a high resistance ground fault. The present invention relates to a ground fault detection system and method using voltage fluctuation rate and harmonic analysis determined as a failure.

As shown in FIG. 1, the electric rail load distribution point for the ground is the highest at the point of electric railroad loading, and the ground potential becomes higher at the near end of the substation. When the electric railroad load is large, The potential changes.

In this case, when the electric vehicle is a heavy load, a relatively large leakage current is generated as compared with the light load, and the rail potential may be increased to an area that can be misoperated as a ground fault when the operation setting of the existing 64P relay is low.

In order to avoid the malfunction of the existing 64P relay and to determine a more accurate ground fault, in the method considering only the existing potential size, it is necessary to operate only when the rate of change is more than the set level in consideration of the rate of voltage change.

Therefore, in the present invention, the electric potential fluctuation due to the running of the electric motor in the normal direction gradually changes to a low gradient, while the electric potential fluctuation shows a sudden change characteristic when the ground fault occurs (see FIG.

On the other hand, in relation to the ground fault protection relay system, numerous applications and disclosures have been made in addition to Korean Patent Laid-Open No. 10-2006-0132420 (hereinafter referred to as "prior art document").

As shown in FIG. 3, the prior art system includes a 64P relay for short-circuiting a ground switch when a ground fault occurs in a direct current feed system for an electric railway; A di / dt distance relay for calculating a distance to a ground fault point on the basis of a change amount of a feed line current formed as the ground switch is short-circuited to trip control the corresponding circuit breaker; It is made, including.

However, the conventional ground fault detection and protection method including the above-mentioned prior art uses a method of judging a ground fault if the potential difference between the rail and the ground detected by the 64P relay is more than the set magnitude and shutting down the entire substation.

Therefore, when the electric potential difference between the rail and the ground is higher than the operating value due to the operation of the electric motor in normal operation, there may occur a malfunction. If the resistance of the high resistance is large when the ground fault occurs, There is a problem that a failure can not be judged only by a combination of the potential difference and the variation rate.

The present invention has been made in view of the above problems, and the ground fault is determined not only by the potential difference between the rail and the ground, but also by the voltage fluctuation rate, and at the same time, the high resistance ground fault is analyzed by analyzing the ratio of the harmonic components of the voltage. An object of the present invention is to provide a ground fault detection system and method using voltage fluctuation rate and harmonic analysis.

The present invention for achieving the technical problem relates to a ground fault detection system using the voltage fluctuation rate and harmonic analysis, the voltage measurement unit for measuring the potential difference between the rail and the ground and the voltage fluctuation rate (ΔV) based on the input voltage; An operation unit determining whether a ground fault occurs by analyzing the voltage variation rate and the harmonic analysis of the voltage measured by the voltage measuring unit; A failure signal output unit that outputs a failure signal according to the determination result of the operation unit when a ground fault occurs; And a relay unit operating after a preset operation delay time under the control of the operation unit. .

The calculator may further include: a first failure determination unit determining whether the voltage variation rate measured by the voltage measurement unit is equal to or greater than a preset voltage variation rate; And a second failure determination unit detecting a ratio of harmonics in the voltage measured by the voltage measuring unit to determine whether the harmonic ratio is equal to or greater than a preset ratio. Characterized in that it comprises a.

The first failure determination unit may determine whether the potential difference measured by the voltage measuring unit is equal to or greater than a predetermined potential difference when the voltage variation rate is equal to or greater than a preset voltage variation rate.

The first failure determination unit may determine that the ground fault occurs when the potential difference is equal to or greater than a preset potential difference, and control the relay to operate after a delay time according to the preset operation delay time.

In addition, the second failure determination unit, if the predetermined ratio or more, it is determined that the high resistance ground fault, and according to the predetermined operation delay time, the relay is controlled to operate after the delay time.

And a setting unit for setting a potential difference, a voltage variation rate, a harmonic ratio, and an operation delay time of the relay unit to determine a ground fault. And further comprising:

On the other hand, the present invention relates to a ground fault detection method using the voltage change rate and harmonic analysis, (a) a step of measuring the potential difference between the rail and the ground and the voltage change rate (ΔV) based on the voltage input voltage; (b) a process of determining, by the calculation unit, whether a ground fault occurs by analyzing the voltage variation rate and the harmonics of the voltage measured through the step (a); (c) a process of outputting a failure signal according to the failure signal output unit when a ground fault occurs as a result of the determination of step (b); And (d) the relay unit operating after a preset operation delay time under the control of the operation unit. .

In addition, the step (b), (b-1) the operation unit determines whether or not the voltage change rate measured by the step (a) is a predetermined voltage change rate or more; (b-2) when the determination result of the step (b-1) is equal to or greater than the preset voltage variation rate, the operation unit determining whether the potential difference measured through the step (a) is greater than or equal to the preset potential difference; And (b-3) when the determination result of the step (b-2) is equal to or more than the preset potential difference, the operation unit causes a ground fault. Determining and controlling the relay to operate after the delay time according to a preset operation delay time; And a control unit.

In addition, the step (b), (b-1 ') the operation unit detects the ratio of harmonics in the voltage measured through the step (a), and determines whether the harmonic ratio is more than a predetermined ratio; And (b-2 ') when the determination result in the step (b-1') is equal to or greater than the preset ratio, the operation unit determines that the ground fault is high resistance, and the relay unit after the delay time is determined according to the preset operation delay time. Controlling to operate; Characterized in that it comprises a.

And before the step (a), (a-1) the process of setting the potential difference, voltage fluctuation rate, harmonic ratio and relay operation delay time for determining the ground fault; Further comprising:

According to the present invention as described above, there is an effect that can determine the ground fault failure by analyzing the harmonic ratio of the voltage, unlike the prior art that can not determine the failure using only the potential difference and the voltage change rate.

Fig. 1 is an example showing the ground current distribution of the return current and the rail.
Fig. 2 is a graph comparing the potential fluctuation at a normal load and a failure.
3 is a block diagram of a conventional ground fault protection relay system.
4 is an overall configuration diagram conceptually showing a ground fault detection system using the voltage fluctuation rate and harmonic analysis according to the present invention.
5 is an exemplary view showing a ground fault detection system using a voltage variation rate and harmonic analysis connected from a rail side and a ground side according to the present invention.
Figure 6 is a graph showing a harmonic-containing voltage waveform when a high resistance ground fault according to the present invention.
7 is a flowchart illustrating a ground fault detection method using a voltage variation rate and harmonic analysis according to the present invention;

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

The ground fault detection system using the voltage variation rate and harmonic analysis according to the present invention will be described with reference to FIGS. 4 to 7.

4 is a conceptual diagram illustrating a ground fault detection system S using voltage fluctuation rate and harmonic analysis according to the present invention, and FIG. 5 is a voltage fluctuation rate and harmonic analysis connected from a rail side and a ground side according to the present invention. An example showing the ground fault detection system using

As shown in FIG. 4, a voltage measuring unit 100, a calculating unit 200, a fault signal output unit 300, a relay unit 400, and a setting unit 500 are included.

The voltage measuring unit 100 measures a potential difference between the rail and the ground and a voltage change rate ΔV based on the input voltage.

The calculation unit 200 performs a function of determining whether a ground fault occurs by analyzing the voltage variation rate and the harmonic analysis of the voltage measured by the voltage measuring unit 100. As shown in FIG. The unit 210 and the second failure determination unit 220 is included.

Specifically, the first failure determining unit 210 determines whether the voltage variation rate measured through the voltage measuring unit 100 is equal to or greater than a predetermined voltage variation rate.

As a result of the determination, if the voltage variation rate is equal to or greater than a predetermined voltage variation rate, the first failure determination unit 210 determines whether the potential difference measured through the voltage measurement unit 100 is equal to or greater than a preset potential difference.

As a result of the determination, if the potential difference is equal to or greater than the preset potential difference, the first failure determining unit 210 determines that the ground fault has occurred and controls the control unit 400 to operate after the delay time according to the predetermined operation delay time.

The second failure determining unit 220 detects a harmonic ratio from the voltage measured by the voltage measuring unit 100 and determines whether the harmonic ratio is equal to or greater than a predetermined ratio.

As a result of the determination, if the predetermined ratio is more than the predetermined ratio, the second failure determination unit 220 determines that the high resistance ground fault is present and controls the relay unit 400 to operate after a delay time according to the predetermined operation delay time.

For reference, in the case of a high resistance ground fault, as shown in FIG. 6, the voltage variation rate? V may not be generated. This is because the magnitude of the leakage current due to the high resistance is smaller than that of the low resistance fault. In addition, an arc is generated due to the high resistance, and the voltage waveform of the arc includes the harmonic component (excluding the DC component). In other words, the fault can be judged by comparing the harmonic ratio of the voltage with the preset value.

The failure signal output unit 300 outputs a failure signal according to the result of the determination of the operation unit 200 as a result of the failure in video and audio.

The relay unit 400 is a normal 64P relay and operates after a preset operation delay time under the control of the operation unit 200 when it is determined that the ground fault has occurred through the operation unit 200.

The setting unit 500 presets a potential difference, a voltage variation rate, a harmonic ratio, and an operation delay time of the relay unit 400 in order to determine the ground fault according to the user's input information.

Hereinafter, a ground fault detection method using the voltage fluctuation rate and harmonic analysis through the above-described system will be described with reference to FIG. 7.

7 is a flowchart illustrating a ground fault detection method using a voltage change rate and a harmonic analysis according to the present invention. As shown in FIG. 5, the setting unit 500 determines a potential difference and a voltage change rate for determining a ground fault according to user input information. , Set the harmonic ratio and the operation delay time of the relay unit 400 (S100), and the voltage measuring unit 100 measures the potential difference between the rail and the ground and the voltage change rate (ΔV) based on the input voltage ( S200).

Thereafter, the calculating unit 200 determines whether the ground fault has occurred, based on the voltage change rate ΔV and the potential difference measured by the voltage measuring unit 100 (S300).

In detail, the calculation unit 200 determines whether the voltage change rate measured by the voltage measurer 100 is greater than or equal to a preset voltage change rate (S310).

As a result of the determination in step S310, when the voltage variation rate is equal to or greater than the preset voltage variation ratio, the first failure determination unit 210 determines whether the potential difference measured by the voltage measuring unit 100 is equal to or greater than the preset potential difference (S320).

As a result of the determination in step S320, when the potential difference is greater than or equal to the preset potential difference, the first failure determination unit 210 determines that the ground fault has occurred, and controls the relay 400 to operate after the delay time according to the preset operation delay time ( S330).

In addition, when the determination result of step S310 is less than the preset voltage variation rate, and when the determination result of step S320 is less than the preset potential difference, the first failure determination unit 210 performs the procedure to step S200.

On the other hand, at the same time as the above-described step S300, the calculation unit 200 detects the ratio of harmonics from the voltage measured by the voltage measuring unit 100, and determines whether or not high resistance ground fault (S300 ').

Specifically, the second failure determination unit 220 of the calculation unit 200 detects the ratio of the harmonics from the voltage measured through the voltage measurement unit 100, and determines whether the harmonic ratio is equal to or greater than a predetermined ratio (S310 ').

As a result of the determination in step S310 ', if the predetermined ratio is greater than the predetermined ratio, the second failure determination unit 220 determines that the high resistance ground fault has occurred and controls the relay unit 400 to operate after the delay time according to the predetermined operation delay time (S320 ').

As a result of the determination in step S310 ', if it is less than the predetermined ratio, the second failure determination unit 220 performs the procedure to step S200.

Subsequently, when it is determined that the ground fault is determined by the first failure determination unit 210 and the second failure determination unit 220 of the operation unit 200, the failure signal output unit 300 displays the corresponding failure signal accordingly. It outputs a voice or the like (S400), the relay unit 400 operates after a predetermined operation delay time under the control of the operation unit 200 (S500).

In the present invention, even if any one of the processes S300 and S300 'performed at the same time is satisfied, the ground fault may be determined and the relay unit may be operated after the failure signal output and the predetermined operation delay time.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It will be appreciated by those skilled in the art that numerous changes and modifications may be made without departing from the invention. Accordingly, all such appropriate modifications and changes, and equivalents thereof, should be regarded as within the scope of the present invention.

S: Ground fault detection system using voltage fluctuation rate and harmonic analysis
100: voltage measuring unit 200:
210: first failure determination unit 220: second failure determination unit
300: Fault signal output unit 400:
500: setting part

Claims (10)

A voltage measuring unit 100 for measuring a potential difference and a voltage variation rate? V between the rail and the ground based on the inputted voltage;
An operation unit 200 for determining a ground fault through harmonic analysis of a voltage variation rate and a voltage measured through the voltage measurement unit 100;
A fault signal output unit 300 for outputting a fault signal corresponding to a ground fault as a result of the determination by the operation unit 200; And
A calculator 400 operated after a predetermined delay time according to the control of the calculator 200; Including but not limited to:
The operation unit 200,
A first failure determination unit 210 for determining whether the voltage variation rate measured through the voltage measurement unit 100 is equal to or greater than a preset voltage variation rate; And
A second failure determination unit 220 for detecting a ratio of harmonics from the voltage measured by the voltage measuring unit 100 to determine whether the harmonic ratio is equal to or greater than a preset ratio; Ground fault detection system using voltage fluctuation rate and harmonic analysis, characterized in that it comprises a.
delete The method of claim 1,
The first failure determination unit 210,
The ground fault detection system using the voltage fluctuation rate and harmonic analysis, characterized in that it is determined whether the potential difference measured by the voltage measuring unit 100 is greater than or equal to a predetermined potential difference when the voltage variation rate is greater than or equal to a preset voltage variation rate.
The method of claim 3, wherein
The first failure determination unit 210,
The ground fault detection system using the voltage fluctuation rate and harmonic analysis, characterized in that it is determined that the ground fault if the predetermined potential difference or more, and according to the predetermined operation delay time, the relay unit 400 to operate after the delay time.
The method of claim 1,
The second failure determination unit 220,
In the case of more than a predetermined ratio, the ground fault detection system using the voltage fluctuation rate and harmonic analysis, characterized in that the high resistance ground fault is determined, and the relay unit 400 operates after the delay time according to the preset operation delay time. .
The method of claim 1,
A setting unit (500) for setting a potential difference, a voltage variation rate, a harmonic ratio, and an operation delay time of the summing unit (400) for ground fault diagnosis; Ground fault detection system using voltage fluctuation rate and harmonic analysis, characterized in that it further comprises.
(a) measuring a potential difference between the rail and the ground and a voltage change rate ΔV based on the voltage input by the voltage measuring unit 100;
(b) a process of determining, by the calculation unit 200, whether a ground fault occurs through the harmonic analysis of the voltage variation rate and the voltage measured through the process (a);
(c) a process of outputting a fault signal according to the fault signal output unit 300 when a ground fault occurs as a result of the determination of step (b); And
(d) the relay unit 400 operating after a preset operation delay time under the control of the operation unit 200; Including,
The step (b)
(b-1) determining, by the calculation unit 200, whether the voltage variation rate measured through the process (a) is greater than or equal to a preset voltage variation rate;
(b-2) when the determination result of the step (b-1) is equal to or greater than the preset voltage variation rate, the operation unit 200 determining whether the potential difference measured through the step (a) is greater than or equal to the preset potential difference; And
(b-3) If the determination result of the step (b-2) is equal to or more than the preset potential difference, the operation unit 200 causes a ground fault. Determining and controlling the relay unit 400 to operate after the delay time according to a preset operation delay time; Ground fault detection method using a voltage change rate and harmonic analysis, characterized in that it comprises a.
delete The method of claim 7, wherein
The step (b)
(b-1 ') the operation unit 200 detecting a ratio of harmonics from the voltage measured through the step (a), and determining whether the harmonic ratio is greater than or equal to a preset ratio; And
(b-2 ') If the determination result in the step (b-1') is equal to or greater than the preset ratio, the operation unit 200 determines that the high resistance ground fault has occurred, and after the delay time according to the preset operation delay time, Controlling all 400 to operate; Ground fault detection method using a voltage change rate and harmonic analysis, characterized in that it comprises a.
The method of claim 7, wherein
Before the step (a)
(a-1) setting unit 500 to set a potential difference, a voltage variation rate, a harmonic ratio, and an operation delay time of the relay unit 400 to determine a ground fault; Ground fault detection method using the voltage fluctuation rate and harmonic analysis, characterized in that it further comprises.

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