JP2006275845A - Lightning current measurement apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform digital processing on a lightning current to calculate a peak value and a charge amount, thereby allowing a lightning current measurement apparatus to be simplified, to be downsized, and to achieve lowered cost. <P>SOLUTION: The lightning current measurement apparatus comprises a sensor section B1 having a current sensor 201 for measuring a lightning current and a sensor I/F section 205, a peak-value calculation section B2 having a peak hold circuit 206 and an A/D conversion section 207, a charge-amount calculation section B3 having an absolute-value circuit 208 and an A/D conversion section 209, a time measurement section D having a GPS receiver 210, a data storage section C having a memory card 203, and an arithmetic processing section A which decides a trigger occurrence, acquires the peak value and the charge amount of the lightning current, and stores these data in the memory card 203 together with a time of the trigger occurrence measured by the time measurement section D. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lightning strike current measuring apparatus which is applied to, for example, wind power generation facilities and the like, measures the peak value and charge amount of a lightning strike current, and stores them together with the lightning occurrence time.

As a lightning current observation apparatus, a conventional technique described in Patent Document 1 described later by the present applicant is known.
This prior art is mounted so that the base of the tower of a workpiece such as a wind power generation facility penetrates, and an annular current sensor inscribed through the insulator with the outer peripheral surface of the base of the tower, An observation device for measuring the peak value that outputs the peak value data to the external monitoring device by calculating and processing the current output from the annular current sensor, and the waveform data by calculating and processing the current output from the annular current sensor And an observation device for waveform measurement output to a monitoring device.

  According to this conventional technology, an observation device can be easily installed using a large-diameter Rogowski coil that surrounds the tower of a wind power generation facility, etc., and the peak value of the lightning current that serves as a guideline for lightning resistance design and resistance design It is now possible to realize a lightning strike current observation device that can accurately measure the waveform.

As another conventional technique, Patent Document 2 discloses a current measuring device that ensures a wide dynamic range in order to measure a lightning strike current, a ground fault / short circuit current, and the like.
In this prior art, after adjusting the output signal of the Rogowski coil to an appropriate value, it is compressed to a certain range by the AGC amplifier, converted into a digital signal by the first A / D converter, and the gain of the AGC amplifier. Using an expensive A / D converter with a wide dynamic range by converting information into digital signals by a second A / D converter and performing a software operation on both of these digital signals with a microcomputer to obtain current measurement values Even if not, an inexpensive A / D converter can be used to realize a current measuring device having a wide dynamic range.

Japanese Patent Laying-Open No. 2005-62080 ([0023] to [0036], FIG. 1, FIG. 4 to FIG. 7 etc.) JP 2001-194390 A ([0011] to [0024], FIGS. 1 to 4 etc.)

On the other hand, with this type of lightning current observation device or measuring device, there is a need for further downsizing and cost reduction in order to further spread the device. Functions and circuit configurations can be reduced by narrowing down the types of measured and recorded data. There is also a strong demand to simplify costs and thereby reduce costs.
Here, the amount of charge due to lightning current has an important meaning in lightning protection design etc., but in the past, commercially available software etc. were used from lightning current waveforms obtained by expensive systems such as high-speed transient recorders and data recorders. The amount of charge is calculated by multiplying the integrated value of the instantaneous current value by the number of measurement samplings.

However, when the charge amount is calculated by the method as described above, the circuit configuration is complicated, the entire apparatus is easily increased in size, and cost reduction is difficult.
Further, in Patent Documents 1 and 2 described above, the calculation of the charge amount of the lightning current is not particularly disclosed.
Therefore, the problem to be solved by the present invention is not to collect the waveform data of the lightning strike current finally, but to directly calculate the peak value and the charge amount by digitally calculating and processing the lightning strike current. An object of the present invention is to provide a lightning strike current measuring device that enables simplification, downsizing, and cost reduction.

In order to solve the above problems, the invention described in claim 1 includes a sensor unit including a current sensor that measures a lightning strike current, and a sensor interface unit that shapes and outputs an output signal waveform of the current sensor,
A first hold unit having a peak hold circuit to which an output waveform of the sensor interface unit is input, and a first A / D converter that converts an analog output signal of the peak hold circuit into a digital signal;
A second arithmetic unit having an absolute value circuit to which an output waveform of the sensor interface unit is input, and a second A / D converter that converts an analog output signal of the absolute value circuit into a digital signal;
A time measuring unit that measures the time with high accuracy using a GPS receiver;
A data storage unit having a removable storage medium;
When the output value of the first A / D converter exceeds a predetermined trigger level, the occurrence of a trigger is determined, and the output value of the first A / D converter is acquired as the peak value of the lightning strike current. An arithmetic processing unit that acquires the charge amount of the lightning current based on the output value of the A / D conversion unit and stores the peak value and the charge amount in the storage medium together with the trigger generation time measured by the time measurement unit; , With.

  According to a second aspect of the present invention, in the first aspect, the current sensor is a Rogowski coil installed so as to surround a lightning current path.

  According to a third aspect of the present invention, in the first or second aspect, a temperature control unit is provided for maintaining the storage medium at a predetermined operating temperature condition.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the storage medium is a memory card.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the measurement apparatus main body is configured by housing all the components except the current sensor in a single case.

  According to the present invention, it is possible to directly obtain a charge amount and a peak value, which are important as a lightning current waveform parameter when considering current withstand capability and insulation design of various devices, by a simple digital calculation and circuit configuration. The apparatus can be reduced in size, weight, and cost, and can greatly contribute to its popularization.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, FIG. 1 is an overall configuration diagram of this embodiment. In FIG. 1, reference numeral 100 denotes a wind power generation facility, and a lightning strike current measuring device according to the present embodiment is installed at the base of the steel tower 101.
This lightning strike current measuring device includes a current sensor 201 such as a Rogowski coil mounted so as to surround the steel tower root portion 101, and a measuring device main body 200A connected to the current sensor 201. A GPS antenna 202 connected to the apparatus main body 200A is provided. Reference numeral 203 denotes a memory card made of SRAM or the like that stores lightning strike data obtained by the measuring apparatus main body 200A, and 300 denotes a notebook PC that collects lightning strike data via the memory card 203.

  Next, FIG. 2 is a functional block diagram of the present embodiment. A is an arithmetic processing unit, B is a lightning current measuring unit, C is a data storage unit, D is a time measuring unit, E is a communication processing unit, and F is a display. Part, G is a temperature control part, H is a power supply part. 2 other than the current sensor 201 and the GPS antenna 202 are housed in a single case, and are installed inside the tower base 101 as the measurement apparatus main body 200A of FIG. ing.

  The arithmetic processing unit A includes a CPU or the like that determines the occurrence of a trigger (that is, the occurrence of a lightning strike) when the peak value of the lightning strike current exceeds a predetermined trigger level, and calculates the peak value of the lightning strike current and the charge amount. It has a function for overall control of the entire operation of the lightning current measurement unit B, data storage unit C, time measurement unit D, communication processing unit E, display unit F, temperature control unit G, and the like.

The lightning strike current measurement unit B includes a sensor unit B1, a peak value calculation unit B2 as a first calculation unit, and a charge amount calculation unit B3 as a second calculation unit. The sensor unit B1 includes the current sensor 201. And a sensor I / F (interface) unit 205. The peak value calculation unit B2 that is the first calculation unit includes the peak hold circuit 206 and the first A / D conversion unit 207, and the charge amount calculation unit B3 that is the second calculation unit includes the absolute value circuit 208 and the first calculation unit B2. The second A / D conversion unit 209 is included.
Here, the peak value calculation unit B2 and the charge amount calculation unit B3 together with the calculation processing unit A constitute a measurement processing unit I.
In addition, operation | movement of sensor part B1 and the measurement process part I is mentioned later.

  The data storage unit C stores data such as the positive / negative peak value of the lightning strike current, the amount of charge, the lightning strike time, and the like calculated and acquired by the arithmetic processing unit A in a memory card 203 as a storage medium. The data storage unit C can store data in a predetermined file format, for example, up to 100 events in the memory card 203, and has a data overwriting prohibiting function and a data saving function when the power is stopped.

The time measuring unit D includes a GPS receiver 210 to which the GPS antenna 202 is connected. The receiver 210 generates a highly accurate time based on the UTC time (Coordinated Universal Time) received via the antenna 202. And output to the arithmetic processing unit A via the clock control unit 211.
Further, the clock measurement unit D has a function of counting time in seconds or less by an external counter, a function of resetting the external counter, and a function of saving the time by the internal clock and the external counter when a trigger due to lightning strikes.

  The communication processing unit E performs serial communication between an external input / output device, a communication device, and the arithmetic processing unit A. The serial communication unit 212 reads and sets a trigger level for determining a lightning strike, It is possible to read and set the time, read and set the effective current value for charge amount calculation, and obtain the status of each part of the apparatus.

  The display unit F has an LED 213 to supply power, an operation state of the arithmetic processing unit A, a reception state of the GPS receiver 210, a lightning data processing state (trigger state), the presence / absence of a memory card 203, and a normal abnormality, It is possible to display the battery of the memory card 203, the state of write protection, the presence of lightning strike data in the memory card 203, and the like.

The temperature control unit G includes a temperature sensor 214 and a heater 215. By energizing the heater 215 according to a decrease in the ambient temperature, the ambient temperature of the memory card 203 is set to a lower limit value (for example, 0 ° C.). ) The above is controlled.
The power supply unit H includes an AC / DC converter 216 that converts commercial power into AC / DC to obtain DC power, and a backup UPS (uninterruptible power supply) 217 that enables power supply even in the event of a power failure. Can be added as an optional device.

Next, FIG. 3 is a circuit diagram showing a configuration of the sensor unit B1.
The sensor unit B 1 detects a current i (t) flowing through the tower base 101 to the ground side during a lightning strike as a differential voltage signal e (t) by the current sensor 201, and this signal e (t) is transmitted via the coaxial cable 204. Then, the waveform is shaped by the integration circuit 205a and the output adjustment circuit 205b by being input to the sensor I / F unit 205.

Here, the voltage signal e (t), the output voltage v (t) of the integrating circuit 205a, and the mutual inductance M between the current sensor 201 and the measurement current path are expressed by Expressions 1 to 3, respectively.
[Formula 1]
e (t) = M × (di (t) / dt)
[Formula 2]
v (t) = (M / RC) × i (t)
[Formula 3]
M = 2 × 10 ⁻⁷ × (NS / r)
In the above equations, R and C are the resistance value and capacitance value of the integrating circuit 205a, N is the number of turns of the current sensor (Rogowski coil), S is the same cross-sectional area, and r is the same radius.

Next, the operation of the present embodiment will be described focusing on the operation of the measurement processing unit I in FIG.
The analog current waveform after waveform shaping output from the sensor I / F unit 205 described above is input to the peak hold circuit 206 constituting the peak value calculation unit B2, and the positive and negative peak values of the current waveform are detected. Hold. This peak hold value is converted into a digital signal at a constant cycle by the A / D conversion unit 207 and input to the arithmetic processing unit A.
In the arithmetic processing unit A, when the digital value input from the A / D conversion unit 207 exceeds a preset trigger level, the occurrence of a trigger, that is, the occurrence of a lightning strike, is determined and acquired as the maximum value data within the calculation time. .

The analog current waveform output from the sensor unit B1 is also input to the absolute value circuit 208 constituting the charge amount calculation unit B3 and converted into an absolute value, and converted into a digital signal by the A / D conversion unit 209 at a constant cycle. The data is converted and input to the arithmetic processing unit A.
In the arithmetic processing unit A, the absolute value of the current within the calculation time is integrated as shown in Equation 4 using the output signal of the A / D conversion unit 209 according to the determination of the occurrence of the trigger by the peak value calculating unit B2. Thus, the charge amount Q due to the lightning strike current is calculated.
[Formula 4]
Q = ∫ | i (t) | dt

At the same time, the arithmetic processing unit A holds the highly accurate time input from the time measuring unit D, and can accurately specify the trigger occurrence time (lightning strike time).
Thereby, the arithmetic processing unit A sends the positive and negative peak values of the lightning strike current, the charge amount, and the trigger occurrence time to the data storage unit C as lightning strike data, and stores and stores them in the memory card 203. The data stored in the memory card 203 may include the address of the measurement device, position information, the number of lightning strikes, an abnormality history of the device state, and the like.
In addition, information such as the presence / absence and normal / abnormality of the memory card 203 can be confirmed by the display unit F as described above, and the operating temperature condition of the memory card 203 can be always properly maintained by the action of the temperature control unit G. Is possible.
The memory card 203 storing the lightning strike data is manually collected and attached to the notebook PC 300 or the like to collect the lightning strike data, which can be used for examining the current withstand capability and insulation design of various devices.

FIG. 4 is a characteristic diagram confirming the crest value measurement function when a lightning impulse current of a predetermined frequency is passed in the above embodiment, where the horizontal axis is the frequency of the lightning impulse current, and the vertical axis is the input / output ratio ( (Measurement current value / applied current value).
As is apparent from FIG. 4, in this embodiment, the input / output ratio is nearly 1 for currents of either positive or negative polarity in a wide frequency band, and has a peak value substantially equal to the applied current value. Current is being measured. Although not shown, it has been confirmed that the input / output ratio is substantially 1 even when the frequency of the applied current is constant and the magnitude thereof is changed.

Further, FIG. 5 is a waveform diagram of a lightning impulse current flowed to confirm the charge amount measurement function in this embodiment, and FIG. 6 is a measured value (crest value and charge) with respect to this lightning impulse current (applied waveform). Amount).
As is clear from FIG. 6, the charge amount of the applied waveform and the measured charge amount are in good agreement, and it was confirmed that this embodiment has a good charge amount measurement function.

  The present invention can be applied not only to wind power generation facilities but also to various facilities and buildings that should measure the peak value and charge amount of lightning current, including power transmission towers that can be equipped with current sensors such as Rogowski coils. Needless to say.

1 is an overall configuration diagram of an embodiment of the present invention. It is a functional block diagram of an embodiment. It is a block diagram of the sensor part in FIG. In an embodiment, it is a characteristic figure (figure showing a relation of frequency-input / output ratio of lightning impulse current) which checked a crest value measurement function at the time of flowing a lightning impulse current of a predetermined frequency. In embodiment, it is a wave form diagram of the lightning impulse current sent in order to confirm an electric charge amount measurement function. It is explanatory drawing of the measured value (crest value and electric charge amount) at the time of flowing the lightning impulse current of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100: Wind power generation equipment 101: Steel tower base part 200A: Measuring apparatus main body 201: Current sensor 202: GPS antenna 203: Memory card 204: Coaxial cable 205: Sensor I / F part 205a: Integration circuit 205b: Output adjustment circuit 206: Peak Hold circuit 207: A / D conversion unit 208: Absolute value circuit 209: A / D conversion unit 210: GPS receiver 211: Clock control unit 212: Serial communication unit 213: LED
214: Temperature sensor 215: Heater 216: AC / DC converter 217: UPS (uninterruptible power supply)
300: Notebook PC
A: Arithmetic processing part B: Lightning strike current measuring part B1: Sensor part B2: Crest value calculating part (first calculating part)
B3: Charge amount calculation unit (second calculation unit)
C: Data storage unit D: Time measurement unit E: Communication processing unit F: Display unit G: Temperature control unit H: Power supply unit I: Measurement processing unit

Claims (5)

A sensor unit having a current sensor that measures a lightning strike current, and a sensor interface unit that shapes and outputs an output signal waveform of the current sensor;
A first hold unit having a peak hold circuit to which an output waveform of the sensor interface unit is input, and a first A / D converter that converts an analog output signal of the peak hold circuit into a digital signal;
A second arithmetic unit having an absolute value circuit to which an output waveform of the sensor interface unit is input, and a second A / D converter that converts an analog output signal of the absolute value circuit into a digital signal;
A time measuring unit that measures the time with high accuracy using a GPS receiver;
A data storage unit having a removable storage medium;
When the output value of the first A / D converter exceeds a predetermined trigger level, the occurrence of a trigger is determined, and the output value of the first A / D converter is acquired as the peak value of the lightning strike current. An arithmetic processing unit that acquires the charge amount of the lightning current based on the output value of the A / D conversion unit and stores the peak value and the charge amount in the storage medium together with the trigger generation time measured by the time measurement unit; ,
A lightning current measuring device comprising: In the lightning strike current measuring device according to claim 1,
A lightning current measuring apparatus, wherein the current sensor is a Rogowski coil installed so as to surround a lightning current path. In the lightning strike current measuring device according to claim 1 or 2,
A lightning strike current measuring device comprising a temperature control unit for maintaining the storage medium at a predetermined operating temperature condition. In the lightning strike current measuring device according to any one of claims 1 to 3,
The lightning strike current measuring device, wherein the storage medium is a memory card. In the lightning strike current measuring device according to any one of claims 1 to 4,
A lightning strike current measuring device characterized in that a measuring device main body is configured by housing all components except the current sensor in a single case.

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