JP2009041976A - Fault point locating method and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fault point locating method and a fault point locating system capable of locating a fault point of a transmission line inexpensively with a simple constitution. <P>SOLUTION: When a surge current generated upon an electric accident of the transmission line 1a flows through a voltage divider 4 into a capacitor C connected between a secondary side circuit of the voltage divider 4 connected to a terminal (bus) 2a of the transmission line 1a for a commercial frequency AC, and the ground, the surge current flowing in the capacitor C is detected by a high-frequency current sensor CT. Then, a fault point of the transmission line is located by a fault point locating device 10 based on a waveform of the surge current detected by the high-frequency current sensor CT and an arrival time of the surge current. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fault location method and a fault location system, and more particularly, a fault in which a fault point is detected by detecting an accident surge waveform generated in an electric accident such as a short circuit of a commercial frequency AC transmission line or a ground fault. The present invention relates to a point location method and a fault location system using the same.

  Conventionally, as a failure point locating method, there is a method of locating a failure point by observing a current of a capacitor connected to a transmission line with a dedicated current sensor (for example, JP-A-1-161165 (Patent Document 1). )reference). As another conventional fault location method, there is a method for obtaining a fault point from the rising slope of current waveforms of a plurality of capacitors connected to a transmission line (see, for example, Japanese Patent No. 3767528 (Patent Document 2)). ).

  In such a surge type fault point locating device using the conventional fault point locating method, a dedicated surge sensor is installed in the vicinity of the transmission line, and the obtained waveform data is used as an electric signal or electro-optical conversion (EO conversion). ) Is sent to the substation building using optical signals and analyzed by a dedicated device installed in the building to locate the failure point.

However, this method requires that a surge sensor be installed in the vicinity of the transmission line, the work on the high-voltage power equipment is dangerous, and because it is outdoors, the surge sensor must also be resistant to the environment. There is also a problem of high cost because wiring work to the building is required. Further, a surge sensor must be installed for each transmission line, and in the case of two circuits and 12 lines, 2 × 12 × 3 = 72 pieces of surge sensors and wiring work between those surge sensors and the building are required.
JP-A-1-161165 Japanese Patent No. 3776728

  Accordingly, an object of the present invention is to provide a fault location that can locate a fault in a transmission line with a simple configuration and at a low cost by using a voltage divider or a measurement transformer which is an existing facility such as a substation. It is to provide a method and a fault location system.

In order to solve the above problems, the fault location method of the present invention is:
The surge current generated at the time of an electrical accident in the transmission line is applied to the capacitor connected between the voltage divider connected to the terminal of the commercial frequency AC transmission line or the secondary circuit of the measuring transformer and the ground. When flowing through the voltage divider or the measuring transformer, the surge current flowing through the capacitor is detected by a current sensor,
Based on the waveform of the surge current detected by the current sensor and the arrival time of the surge current, the failure point of the transmission line is determined by a failure point locating device.

  As a result of investigating the propagation of surges that occurred at the time of an electrical accident in a transmission line at a substation with power equipment connected to the terminal of a commercial frequency AC transmission line, the present applicant found that a voltage divider that is an existing power installation Alternatively, the surge current waveform component is extracted from the secondary circuit of the measurement transformer, and the extracted surge current waveform component can be used for fault location.

  By utilizing such surge propagation characteristics, according to the fault location method of the above configuration, the secondary side circuit of the voltage divider (or measurement transformer) connected to the terminal of the commercial frequency AC transmission line. When a surge current generated during an electrical accident in the transmission line flows through the voltage divider (or measurement transformer) to the capacitor connected between the capacitor and the ground, the capacitor detected by the current sensor Based on the waveform of the surge current flowing and the arrival time of the surge current, the failure point of the transmission line is located by the failure point locating device, so that the voltage divider 2 or the measurement transformer connected to the terminal of the transmission line One set of the capacitor, current sensor, and failure point locating device may be installed in the secondary circuit, and the cost can be greatly reduced. In addition, the cables of existing measuring transformer lines can be used as they are until the installation location of the fault location device such as the switchboard room. Furthermore, the failure point locating device may have a specification for indoor installation, and does not need to satisfy the environmental resistance performance based on the outdoor installation standard. Therefore, the failure point of the transmission line can be determined with a simple configuration and at a low cost.

  Further, in the failure point locating method of one embodiment, the failure point locating device calculates a correlation function between the waveform of the leading surge portion of the surge current waveform detected by the current sensor and the subsequent waveform portion. The point on the time axis at which the absolute value of the correlation function is calculated is the arrival time of the reflected wave of the surge current, the arrival time of the leading portion of the surge current and the arrival time of the reflected wave of the surge current Based on the above, the failure point of the transmission line is determined.

  According to the above embodiment, the failure point locator calculates a correlation function between the waveform of the leading surge portion and the waveform portion thereafter from the surge current waveform detected by the current sensor, and the correlation function The point on the time axis at which the absolute value of the peak current reaches is the arrival time of the reflected wave of the surge current, and the failure point of the transmission line based on the arrival time of the leading portion of the surge current and the arrival time of the reflected wave of the surge current By locating, fault location can be performed with high accuracy and at high speed.

Moreover, in the fault location method of one embodiment,
A system having a configuration in which a plurality of the transmission lines are connected,
Based on the information indicating the section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines, the failure point locating device causes the failure of the transmission line to the section of the transmission line in which the electrical accident has occurred. Locate the point.

  According to the embodiment, in a system having a configuration in which a plurality of transmission lines are connected, an electrical accident is performed by the fault location device based on information indicating a section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines. By locating the failure point of the transmission line for the section of the transmission line where the failure occurred, it is possible to identify the failure line by identifying the transmission line where the electrical accident occurred without using sensors for the number of transmission lines. .

  Further, in the fault location method according to an embodiment, the information indicating the section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines is an operation signal of a protection relay of the transmission line in which the electrical accident has occurred. It is.

  According to the embodiment, as the information indicating the section of the power transmission line in which the electrical accident has occurred among the plurality of power transmission lines, the operation signal of the protection relay of the power transmission line in which the electrical accident has occurred is used. The cost can be reduced as compared with the case of installing this sensor.

In the fault location system of the present invention,
A voltage divider connected to a terminal of a commercial frequency AC power transmission line or a secondary side circuit of a measurement transformer and a ground, and a surge current generated at the time of an electrical accident of the power transmission line is a voltage divider. Or a capacitor flowing through the measuring transformer,
A current sensor for detecting the surge current flowing in the capacitor;
And a failure point locating device for locating a failure point of the transmission line based on a waveform of the surge current detected by the current sensor and an arrival time of the surge current.

  According to the above configuration, the electric power of the transmission line is connected to the capacitor connected between the secondary side circuit of the voltage divider (or measurement transformer) connected to the terminal of the commercial frequency AC transmission line and the ground. When a surge current generated at the time of an accident flows through a voltage divider (or measurement transformer), it is sent based on the waveform of the surge current flowing through the capacitor detected by the current sensor and the arrival time of the surge current. By locating the failure point of the electric wire with the failure point locating device, the capacitor, current sensor, and failure point locating device are connected to the secondary circuit of the voltage divider or measuring transformer connected to the terminal of the transmission line. It is only necessary to install a set, and the cost can be greatly reduced. In addition, the cables of existing measuring transformer lines can be used as they are until the installation location of the fault location device such as the switchboard room. Furthermore, the failure point locating device may have a specification for indoor installation, and does not need to satisfy the environmental resistance performance based on the outdoor installation standard. Therefore, the failure point of the transmission line can be determined with a simple configuration and at a low cost.

Moreover, in the fault location system of one embodiment,
The above fault location device is
A leading surge extraction unit that extracts a waveform of a leading surge portion of the surge current waveform detected by the current sensor;
A correlation function calculating unit that calculates a correlation function between the waveform of the first surge portion of the surge current waveform extracted by the first surge extraction unit and the waveform portion thereafter;
The point on the time axis at which the absolute value of the correlation function calculated by the correlation function calculation unit peaks is the arrival time of the reflected wave of the surge current, and the arrival time of the leading portion of the surge current and the reflection of the surge current A failure point locating unit for locating the failure point of the transmission line based on the arrival time of the wave.

  According to the above embodiment, the waveform of the leading surge portion of the surge current waveform detected by the current sensor is extracted by the leading surge extraction unit, the extracted waveform of the leading portion and the subsequent waveform portion, The correlation function is calculated by the correlation function calculation unit, the point on the time axis at which the absolute value of the correlation function peaks is the arrival time of the reflected wave of the surge current, and the arrival time of the surge current and the surge By locating the failure point of the transmission line by the failure point locating unit based on the arrival time of the reflected wave of the current, the failure point locating can be performed with high accuracy and at high speed.

Moreover, in the fault location system of one embodiment,
A system having a configuration in which a plurality of the transmission lines are connected,
The failure point locating device is configured to detect a failure of the transmission line with respect to a section of the transmission line in which the electrical accident has occurred based on information indicating a section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines. Locate the point.

  According to the embodiment, in a system having a configuration in which a plurality of transmission lines are connected, an electrical accident is performed by the fault location device based on information indicating a section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines. By locating the failure point of the transmission line for the section of the transmission line where the failure occurred, it is possible to identify the failure line by identifying the transmission line where the electrical accident occurred without using sensors for the number of transmission lines. .

Moreover, in the fault location system of one embodiment,
Information indicating the section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines is an operation signal of a protection relay of the transmission line in which the electrical accident has occurred,
The failure point locating device has a signal input unit to which an operation signal of a protection relay of the power transmission line is input.

  According to the embodiment, as the information indicating the section of the power transmission line in which the electrical accident has occurred among the plurality of power transmission lines, the operation signal of the protection relay of the power transmission line in which the electrical accident has occurred is used. The cost can be reduced as compared with the case of installing this sensor.

  As is clear from the above, according to the fault location method and fault location system of the present invention, the voltage divider or the measurement transformer, which is an existing facility such as a substation, is used, so that the transmission can be performed at low cost. A failure point locating method and a failure point locating system capable of locating a failure point of an electric wire can be realized.

  Hereinafter, the failure point locating method and the failure point locating system of the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1A shows a schematic diagram of a fault location system and a power system using a fault location method according to an embodiment of the present invention. In FIG. 1A, 1a is a three-phase transmission line of two parallel lines to be observed. 1b is a parallel two-line three-phase transmission line of a voltage class different from that of the transmission line 1a, 2a is a terminal (bus) connected to one end of the transmission line 1a, and 2b is a terminal connected to one end of the transmission line 1b (Bus) 3 is a transformer connecting the terminal (bus) 2a of the transmission line 1a and the terminal (bus) 2b of the transmission line 1b, and 4 is a voltage divider (Potential Divider) that detects the voltage of the terminal (bus) 2a. ) 5 is a surge countermeasure arrester connected between the secondary circuit of the voltage divider 4 and the ground, and C is connected between the secondary circuit of the voltage divider 4 and the ground, A capacitor for dividing the current, CT is a high frequency for detecting a high frequency current flowing in the capacitor C. A current sensor 11 is a current waveform recording unit that records a surge current that is a high-frequency current detected by the high-frequency current sensor CT and its arrival time, and 12 is a surge current that is recorded in the current waveform recording unit 11 and its arrival time. It is a current waveform analysis unit for locating the failure point based on. As an example of information indicating the section of the power transmission line in which the electrical accident has occurred among the plurality of power transmission lines in the current waveform recording unit 11 and the current waveform analysis unit 12, protective relays for the transmission lines 1 a and 1 b in which the electrical accident has occurred The operation signal (relay contact) is input. Here, the information indicating the section of the power transmission line in which the electric accident has occurred among the plurality of power transmission lines is not limited to the operation signal of the protection relay, and other circuits representing the information indicating the section of the power transmission line in which the electric accident has occurred These signals may be used.

  The current waveform recording unit 11 and the current waveform analysis unit 12 constitute a failure point locating device 10. The capacitor C, the high-frequency current sensor CT, and the failure point locating device 10 constitute a failure point locating system.

  Instead of the voltage divider 4, a surge shunt capacitor may be installed in the secondary side circuit of the measurement transformer (Potential Transformer). Further, a surge countermeasure capacitor may be used in place of the surge countermeasure arrester 5.

  In the current waveform recording unit 11, the capacitor of the secondary side circuit of the voltage divider 4 (or measurement transformer) normally installed in the power transmission equipment of the three-phase AC transmission line of commercial frequency or the power transmission equipment of the power receiving terminal. The surge current waveform flowing through C is sampled at a sampling frequency of about 10 MHz or more, and the current waveform data for a predetermined time is always held in the ring buffer, and the protection relay operation signal (relay contact) in the event of a system fault Is input, for example, 60 msec before the accident and 140 msec after the accident are recorded for a total of 200 msec waveform data.

  FIG. 1B shows a block diagram of the current waveform analyzer 12.

  As shown in FIG. 1B, the current waveform analysis unit 12 receives the surge current waveform data from the current waveform recording unit 11 and extracts a leading surge waveform from the leading surge extraction unit 12a and the leading surge extraction unit 12a. A correlation function calculation unit 12b that calculates a correlation function using a mother wavelet function Ψ (t) obtained based on the extracted leading surge waveform, and a reflected wave by the correlation function calculated by the correlation function calculation unit 12b A fault location unit 12c for detecting a surge waveform and locating the fault point of the transmission line based on the arrival time and absolute value of the leading surge waveform and the arrival time and absolute value of the reflected wave surge waveform, and a protection relay for the transmission line An operation contact (not shown) is input, and a signal input unit 12d for outputting a signal representing the operation contact input to the fault location unit 12c.

  Here, the signal input unit 12d receives an operation contact of a protection relay (not shown) for each power transmission line in a system having a configuration in which a plurality of power transmission lines are connected. You can see if it is an electrical accident.

  According to the fault location system of the above configuration, it occurs in the secondary circuit of the voltage divider 4 (or measurement transformer) connected to the terminal (bus) 2a of the transmission line 1a in the event of an electrical accident on the transmission line Accident surge waveform data (including the accident start point) is sampled by the current waveform recording unit 11.

  Next, in the current waveform analysis unit 12, the accident surge waveform data sampled by the current waveform recording unit 11 is converted into a dedicated wavelet transform using Equation 3 with the beginning of the accident as a mother wavelet and a scale factor of 1. By (correlation function calculation of the accident start partial waveform and the subsequent waveform), the waveform data of the conversion result is obtained and further converted into an absolute value to detect the peak point, and the reflected wave surge waveform and its arrival time are obtained.

  Next, the power transmission line where the electric accident has occurred is recognized based on the configuration of the system including the input of the operating contact of the protection relay and the power transmission line. Here, for example, if the transmission line where the accident occurred is a simple transmission line without branching, and it is known that the accident point is the closest end, the reflected wave surge is observed after the first surge is observed. The approximate distance to the accident point can be calculated by dividing the time difference until arriving by 2 and multiplying by the surge propagation speed (approximately 280 to 300 m / μsec).

  However, the reflected wave is not necessarily a reflected wave from the accident point, but may be a reflected wave from the power receiving end. In a two-line transmission line, a reflected wave propagating to the transmission end via a non-accident line is also included. Because there is a possibility, there are cases where the above method cannot be correctly positioned. Therefore, the arrival time and absolute value of the direct wave of the virtual accident waveform and the arrival time and absolute value of the reflected wave are predicted by simulation while moving the virtual failure point along the transmission line where the electric accident occurred. A virtual failure point corresponding to the predicted arrival time and absolute value of the direct wave and the arrival time and absolute value of the reflected wave that are most correlated with the arrival time and absolute value and the arrival time and absolute value of the reflected wave. The failure point of the transmission line.

  In addition, other methods may be used for fault location. For example, in the case of a transmission line without a branch, a voltage divider or meter installed on the transmission line or the substation bus at both ends of the transmission line. A surge current observation device synchronized in time by GPS or the like on the secondary side of the transformer for power supply, and observe the surge current on the secondary side of the voltage divider or instrument transformer to determine from the arrival time difference of the surge waveform Etc. may be used.

  Voltage dividers (Potential Dividers) and measurement transformers (Potential Transformers) installed in substations, etc. are not able to pass external surges, although they are considerably attenuated, as a result of their characteristic tests. I understand. Usually, secondary circuits of voltage dividers or measuring transformers are often equipped with surge suppression products such as arresters and capacitors, so generally it is not possible to observe surge waveforms in substation buildings. It was difficult.

  Therefore, the applicant of the present application observes the surge current waveform in the secondary side circuit, not the voltage waveform of the secondary side circuit of the voltage divider or measuring transformer, and converts it into a voltage by the high-frequency current sensor CT. When it was amplified with an amplifier (not shown), it was found that the surge waveform was observed with a sufficiently detectable amplitude. Furthermore, it was also found that this surge current waveform propagates through the transformer for transformer in the substation with little delay.

  FIG. 2 shows an example of the voltage waveform of the output of the measuring transformer, and shows the waveforms of the phase voltage Va, the phase voltage Vb, and the phase voltage Vc from the top. FIG. 3 shows the current waveform of the output of the high-frequency current sensor, and shows an example of the A-phase, B-phase, and C-phase surge current waveforms from the top.

  In the voltage waveform of the measuring transformer shown in FIG. 2, the surge waveform and its reflected wave are not obvious, but in the current waveform of the output of the high frequency current sensor shown in FIG. 3, the leading surge waveform and its reflected wave surge waveform are visually observed. Can be read.

  Although the distance to the failure point can be estimated from the time difference between the leading surge waveform and the reflected surge waveform in FIG. 3, it is necessary to visually check the surge waveform every time, and this is not efficient.

  Therefore, in the present invention, a relatively slow vibration component is eliminated by the high-pass filter, and a correlation function between the head surge waveform portion and other waveform portions is calculated and represented on the graph shown in FIG.

  FIG. 4 shows the filtered surge waveform and the conversion result based on the correlation function. From the top, the original waveform (surge waveform), the fluctuation component (the component removed by the high-pass filter), the surge component, the surge (noise cut), and the converted waveform ( Absolute value).

  The method of estimating the arrival time of the surge waveform using the correlation function is a conventional technique, but the waveform of the secondary circuit of the transformer for measurement at the substation is usually a vibration waveform due to complex factors for both voltage and current. The waveform of the surge on the primary side of the transformer for measurement is completely different from the surge waveform, and continues to vibrate while being attenuated over a considerable time determined by the time constant of the secondary side circuit. For this reason, it was thought that it was difficult to estimate the arrival time of the surge waveform generated on the transmission line from the waveform of the secondary circuit of the measuring transformer.

  Normally, voltage dividers and transformers for measurement cannot propagate surge waveform components of several MHz due to their frequency characteristics with sufficient gain for observation, and surge waveform components from the secondary side circuit cannot be transmitted. The general idea was that it was difficult to extract.

  For this reason, surge type failure point locating devices generally use a method in which a dedicated sensor is placed near the transmission line to detect surges, but equipment installed outdoors requires environmental resistance and is very expensive. It is not realistic to install it for each track.

  In the fault location method of the present invention, a surge waveform component is extracted from the secondary circuit of a measurement transformer, which is an existing facility, and it is verified whether it can be used for fault location.

  As a result, it has been found that a surge waveform component that can be sufficiently used for fault location can be detected.

  Fig. 5 shows an example of reflected wave surge detection. From the top, the original waveform (surge waveform), fluctuation component (component removed by high-pass filter), surge component, surge (noise cut), and converted waveform (absolute value) are shown. ing.

  Next, FIG. 6A and FIG. 6B show an example of the results of investigation of surge propagation in the substation. FIG. 6A shows an example of a surge waveform at the time of an electrical accident in a 154 kV transmission line, and FIG. The enlarged view of the area | region S of FIG. 6A is shown. According to this, it can be understood that the 77 kV system has a steeper change in the waveform, the change point is easy to understand, and is suitable for fault location, despite the electric accident of the 154 kV system.

  Further, although a transformer is installed between the 154 kV system and the 77 kV system, it can be seen that it takes almost no time for the propagation of the surge through the transformer.

  By applying such a surge propagation phenomenon, it has been found that if there is information on which transmission line is the fault line, fault location can be performed even in the case of an electrical accident of a transmission line of a different voltage class. Actually, FIG. 5 is calculated by using the surge waveform of the secondary side circuit of the measuring transformer of the 77 kV system in spite of the electrical accident of the transmission line of the 154 kV system.

  Next, differences (a) to (d) between the prior art and the present invention will be described.

(a) Necessary number of devices Conventionally, a sensor is required for each track to be standardized, but in the present invention, if one is installed in the secondary voltage circuit of the voltage divider or measuring transformer of the bus, Well, it may be possible to localize even in the case of electrical accidents on transmission lines of different voltage classes.

(b) Installation cable Conventionally, a dedicated cable from the vicinity of the transmission line to the waveform recording device is required, but in the present invention, the cable of the existing measurement transformer line can be used as it is to the switchboard room.

(c) Environmental resistance performance Conventionally, since an outdoor installation part occurs, the environmental resistance performance and specifications based on the outdoor installation standard are required for that part, whereas in the present invention, the fault location device is installed indoors. Specifications are good.

(d) Accident line information Conventionally, as many sensors as the number of target lines are installed, so no information on the accident line is required. In the present invention, however, information regarding the accident line is input separately. Although it is necessary, the cost required to input the contact information is relatively low compared to the case where sensors corresponding to the number of lines are installed.

  Thus, it can be seen that the failure point locating method of the present invention has a great cost merit compared with the conventional surge detection type failure point locating method.

  Next, “correlation between the waveform of only the head portion of the surge waveform and the subsequent waveform” will be described.

The defining formula of the autocorrelation function G (τ) is expressed by the following formula 1.

Here, f (t) is the original function, T is the integration interval, and τ is the time factor.

On the other hand, the wavelet transform is defined as the following equation 2.

Here, f (t) is an original function, Ψ (t) is a mother wavelet function, τ is a time factor, and a is a scale factor.

  This mother wavelet function Ψ (t) has only the constraint that the integral exists in the interval [−∞, + ∞] (does not become ∞), and the interval [−∞, + ∞ as in the case of the autocorrelation function. ], It does not mean that the product must be an integral of the same functions with a time difference τ. Therefore, in the calculation method used in the present invention, the absolute value is obtained by performing wavelet transformation when the head surge portion is the mother wavelet function Ψ (t) and the scale factor a is 1.

The conversion formula for obtaining the correlation function G (τ) in the fault location method of the present invention is expressed by the following formula 3.

  Next, a method for recognizing the surge arrival time will be described.

  1) First, wavelet conversion is performed using the head surge waveform as a mother wavelet function.

  FIG. 7 is a diagram for explaining the wavelet transform to which Expression 3 is applied. As shown in FIG. 7, the section from the time T1 to T1 + τ in the original waveform f (t) is the head. As the surge waveform, this leading surge waveform is a mother wavelet function Ψ (t). Then, the mother wavelet function Ψ (t) becomes Ψ (t−τ) as the time factor τ increases and moves in the time axis direction.

  Then, the product of the mother wavelet function Ψ (t−τ) and the original waveform f (t) is integrated.

  2) Convert the wavelet transform integration result to an absolute value.

  FIG. 8A shows the integration result of Equation 3, and FIG. 8B shows a waveform obtained by converting the integration result into an absolute value. In FIG. 8B, the peak point is determined by determining the peak of the two previous peaks and the peak of the subsequent two peaks. This peak point represents the position of the reflected wave surge waveform.

  FIG. 9 shows an example in which the fault location method of the present invention is applied. As shown in FIG. 9, the mother wavelet function Ψ (t−τ) is calculated while moving the section of the head surge waveform surrounded by a circle in the time axis direction, and the mother wavelet function Ψ (t−τ) and A result obtained by integrating the product of the original waveform f (t) to obtain an absolute value is a converted total waveform shown on the lower side.

  In calculating the correlation function, “the waveform at the head of the surge waveform” is extracted as follows.

  In conventional fault location devices, only the surge component must be detected from the surge waveform superimposed on the commercial voltage or current waveform, so various detection methods have been considered (Patent No. 1). 3767528 et al.). However, in the fault location method of the present invention, the surge current component in the secondary circuit of the transformer for measurement at the substation is observed, so the amplitude when there is no electrical accident is close to zero. In the actual fault location device, the time point after detecting the amplitude of about 10% or more of the maximum amplitude portion based on the previous waveform from about 20 msec before the accident detection portion is used as a reference, and thereafter The data for 50 μsec (500 samples) is defined as “the waveform at the head of the surge waveform”.

  The integral value of the product of the two functions of the mother wavelet function Ψ (t) and the original function f (t) has the maximum absolute value at the part where the two functions have similar waveforms (peak point ).

  FIG. 10 shows a simulated surge waveform for explaining the converted waveform and its conversion result. In FIG. 10, the horizontal axis represents time [number of samples] and the vertical axis represents current level [arbitrary scale].

  As shown in FIG. 10, 250 samples are used as the mother wavelet function Ψ (t) from the peak point of the leading surge waveform in the original waveform indicated by the thick line, and the mother wavelet function Ψ (t) and the original The thin line represents the result of integrating the product of the waveform of で in the interval [−∞, + ∞] into an absolute value. In this conversion result, there are two peak points of the reflected wave surge waveform in addition to the peak point of the leading surge waveform.

  The conversion results when the time width of the mother wavelet function Ψ (t) in FIG. 10 is varied are shown in FIGS.

  FIG. 11 shows a simulated surge waveform for explaining the converted waveform when 100 samples are used as the mother wavelet function Ψ (t) from the peak point of the leading surge waveform in the original waveform indicated by a thick line, and the conversion result. Is shown.

  FIG. 12 shows a simulated surge waveform for explaining a converted waveform when 50 samples are used as the mother wavelet function Ψ (t) from the peak point of the leading surge waveform in the original waveform indicated by a thick line, and its waveform. The conversion result is shown.

  FIG. 13 shows a simulated surge waveform for explaining the converted waveform when 25 samples are used as the mother wavelet function Ψ (t) from the peak point of the leading surge waveform in the original waveform indicated by a thick line and its waveform. The conversion result is shown.

  As shown in FIGS. 11, 12, and 13, it can be seen that the position of the peak point of the conversion result does not change even if the time width of the mother wavelet function Ψ (t) is considerably varied.

  According to the fault location method and the fault location system using the fault location method of the above embodiment, the secondary side circuit of the voltage divider (or measurement transformer) connected to the terminal of the commercial frequency AC transmission line and the ground When a surge current generated during an electrical accident on the transmission line flows through a voltage divider (or a measurement transformer), the capacitor connected between and flows into the capacitor detected by a high-frequency current sensor. Based on the surge current waveform and the arrival time of the surge current, the failure point of the transmission line is located by the failure point locating device, so that the voltage divider (or measuring transformer) connected to the terminal on the transmission line One set of the capacitor C, the high-frequency current sensor CT, and the failure point locating device 10 may be installed in the secondary side circuit, and the cost can be greatly reduced. In addition, the cables of existing measuring transformer lines can be used as they are until the installation location of the fault location device such as the switchboard room. Furthermore, the failure point locating device may have a specification for indoor installation, and does not need to satisfy the environmental resistance performance based on the outdoor installation standard. Therefore, it is possible to realize a failure point locating system that can determine a failure point of a transmission line with a simple configuration and at a low cost.

  In general, it is very costly to install waveform detection means directly on high-voltage transmission lines, and the substations of electric power companies are usually built on very large sites. Since several hundred meters must be transmitted, the existing voltage divider (or measuring transformer) and the existing cable of the secondary side circuit are used as they are, so that the cost becomes much lower.

  Usually, the frequency characteristic of the voltage converter is up to several tens of kHz, and it has been considered that waveforms of several hundreds of kHz to several MHz cannot be observed. However, instead of observing the voltage waveform on the secondary side of the voltage divider (or measurement transformer), as a result of observing the surge current in the secondary circuit of the voltage divider (or measurement transformer), It was found that the surge current waveform at the time of the accident can be easily detected. The failure point locating method and the failure point locating system using the failure point locating method of the present invention are obtained by locating a failure point using this surge current waveform.

  In addition, the waveform of the leading surge portion of the surge current waveform detected by the high-frequency current sensor CT is extracted by the leading surge extraction unit 12a, and the correlation between the extracted waveform of the leading portion and the subsequent waveform portion is extracted. The function is calculated by the correlation function calculation unit 12b, and the point on the time axis at which the absolute value of the correlation function peaks is defined as the arrival time of the reflected wave of the surge current, and the arrival time of the surge current and the surge current By locating the failure point of the transmission line by the failure point locating unit 12c based on the arrival time of the reflected wave, the failure point locating can be performed with high accuracy and at high speed.

  Further, in the system having a configuration in which a plurality of the transmission lines are connected, the fault location device 10 transmits the transmission in which the electrical accident has occurred based on the information indicating the section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines. By locating the failure point of the transmission line with respect to the section of the electric wire, the failure point can be determined by identifying the transmission line in which the electric accident has occurred without using sensors for the number of transmission lines.

  In addition, as the information indicating the section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines, sensors for the number of lines are installed by using the operation signal of the protection relay of the transmission line in which the electrical accident has occurred. Cost can be reduced compared to the case.

  In ordinary substations, the timing and period for stopping power transmission are limited, and the timing and period for installing the fault location device in the substation is also limited. In such a situation, according to the fault location method and fault location system using the fault location method of the present invention, the secondary side of the transformer for measuring the bus voltage of the lower voltage class in the substation can cause the surge surge of the high voltage system. Observed by the circuit, for example, as shown in FIGS. 6A and 6B, the accident surge waveform of the 154 kV system can be detected as a surge current component in the secondary circuit of the measuring transformer for the bus of the 77 kV system.

  Although specific embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention.

FIG. 1A is a schematic diagram of a fault location apparatus and a power system using the fault location method according to an embodiment of the present invention. FIG. 1B is a block diagram of a current waveform analysis unit of the fault location apparatus. FIG. 2 is a diagram showing a voltage waveform of the output of the measuring transformer. FIG. 3 is a diagram showing a current waveform of the output of the high-frequency current sensor. FIG. 4 is a diagram showing a conversion result by the filtered surge waveform and the correlation function. FIG. 5 is a diagram illustrating an example of detection of a reflected wave surge. FIG. 6A is a diagram illustrating an example of a surge waveform at the time of an electrical accident in a 154 kV transmission line. FIG. 6B is an enlarged view of the region S shown in FIG. 6A. FIG. 7 is a diagram for explaining wavelet transformation. FIG. 8A is a diagram showing the integration result of the wavelet transform, and FIG. 8B is a diagram showing a waveform obtained by converting the integration result into an absolute value. FIG. 9 is a diagram showing an example in which the fault location method of the present invention is applied. FIG. 10 is a diagram showing a simulated surge waveform for explaining the converted waveform and its conversion result. FIG. 11 is a diagram showing a simulated surge waveform for explaining a converted waveform and a result of the conversion when the head surge waveform of 100 samples is used as the mother wavelet function Ψ (t). FIG. 12 is a diagram showing a simulated surge waveform for explaining a converted waveform and a result of the conversion when the first sample surge waveform of 50 samples is used as the mother wavelet function Ψ (t). FIG. 13 is a diagram showing a simulated surge waveform for explaining a converted waveform and a result of the conversion when the first surge waveform of 25 samples is used as the mother wavelet function Ψ (t).

Explanation of symbols

1a: Parallel 2-line 3-phase transmission line 1b: Parallel 2-line 3-phase transmission line 2a: Terminal (bus)
2b ... Terminal (bus)
DESCRIPTION OF SYMBOLS 3 ... Transformer 4 ... Voltage voltage divider 5 ... Arrestor for surge countermeasures 10 ... Fault location device 11 ... Current waveform recording part 12 ... Current waveform analysis part 12a ... Lead surge extraction part 12b ... Correlation function calculation part 12c ... Fault location Part 12d ... Signal input part C ... Capacitor CT ... High frequency current sensor

Claims (8)

The surge current generated at the time of an electrical accident in the transmission line is applied to the capacitor connected between the voltage divider or the secondary circuit of the measuring transformer connected to the terminal of the commercial frequency AC transmission line and the ground. When flowing through the voltage divider or the measuring transformer, the surge current flowing through the capacitor is detected by a current sensor,
A failure point locating method, wherein a failure point locating device locates a failure point of the transmission line based on a waveform of the surge current detected by the current sensor and an arrival time of the surge current. In the fault location method according to claim 1,
The fault locator calculates a correlation function between the waveform of the leading surge portion and the waveform portion after the surge current waveform detected by the current sensor, and the absolute value of the correlation function is peaked. The point on the time axis becomes the arrival time of the reflected wave of the surge current, and the failure point of the transmission line is determined based on the arrival time of the leading portion of the surge current and the arrival time of the reflected wave of the surge current A fault location method characterized by: The failure point locating method according to claim 1 or 2,
A system having a configuration in which a plurality of the transmission lines are connected,
Based on the information indicating the section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines, the failure point locating device causes the failure of the transmission line to the section of the transmission line in which the electrical accident has occurred. A fault location method characterized by location of points. In the failure point locating method according to claim 3,
The fault location method, wherein the information indicating the section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines is an operation signal of a protection relay of the transmission line in which the electrical accident has occurred. A voltage divider connected to a terminal of a commercial frequency AC power transmission line or a secondary side circuit of a measurement transformer and a ground, and a surge current generated at the time of an electrical accident of the power transmission line is a voltage divider. Or a capacitor flowing through the measuring transformer,
A current sensor for detecting the surge current flowing in the capacitor;
A failure point locating system comprising: a failure point locating device for locating a failure point of the transmission line based on a waveform of the surge current detected by the current sensor and an arrival time of the surge current. In the fault location system according to claim 5,
The above fault location device is
A leading surge extraction unit that extracts a waveform of a leading surge portion of the surge current waveform detected by the current sensor;
A correlation function calculating unit that calculates a correlation function between the waveform of the first surge portion of the surge current waveform extracted by the first surge extraction unit and the waveform portion thereafter;
The point on the time axis at which the absolute value of the correlation function calculated by the correlation function calculation unit peaks is the arrival time of the reflected wave of the surge current, and the arrival time of the leading portion of the surge current and the reflection of the surge current A failure point locating system comprising: a failure point locating unit for locating a failure point of the transmission line based on a wave arrival time. In the fault location system according to claim 5 or 6,
A system having a configuration in which a plurality of the transmission lines are connected,
The failure point locating device is configured to detect a failure of the transmission line with respect to a section of the transmission line in which the electrical accident has occurred based on information indicating a section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines. A fault location system characterized by locating points. In the fault location system according to claim 7,
Information indicating the section of the transmission line in which the electrical accident has occurred among the plurality of transmission lines is an operation signal of a protection relay of the transmission line in which the electrical accident has occurred,
The fault location system has a signal input unit to which an operation signal of a protection relay of the power transmission line is input.