KR100996141B1 - Power quality measuring system and divider circuit used in there - Google Patents

Abstract

A power quality measurement system and a divider circuit used therein are disclosed. The power quality measurement system according to the present invention includes an input unit including an impulse divider for measuring an impulsive transient voltage, and an AC divider for measuring an AC voltage; And an A / D converter for measuring an impulse voltage for sampling the signal measured by the impulse divider, an A / D converter for measuring an AC power supply for sampling the signal measured by the AC divider, and an A / D for measuring the impulse voltage And a signal processing unit having a converter and a controller for processing a signal output from the AC power measurement A / D converter. As a result, the power quality measurement system and the divider circuit used therein can monitor the transient voltage for a long time and simultaneously monitor the commercial AC voltage.

Transient Voltage, Power Quality, Impulse Voltage, AC Power, Divider

Description

Power quality measuring system and divider circuit used in there

The present invention relates to a power quality measuring system and a divider circuit used therein. More particularly, the present invention can monitor a transient voltage that cannot be measured by a power quality analysis device for a long time, and at the same time, can monitor a commercial AC voltage. A measurement system and a divider circuit used therein.

Recently, the frequency of lightning strikes in Korea is increasing year by year along with the global weather. As a result, the number of accidents that cause damage to devices or interrupt services such as electricity and communication due to lightning and surges is increasing. This type of fault is not only extremely resistant to surges such as lightning strikes due to the miniaturization, integration, and digitalization of electronic and communication equipment used in the field, but also the occurrence of an accident in one place because the devices are connected to each other through a network. This is because the spread to other devices can be easily transferred.

Damage caused by transient voltages such as lightning and surge is not only a direct loss due to the burnout of the equipment in operation, but also an indirect loss due to interruption of the production process, data loss and network service interruption. In recent years, the defect rate of products and equipment failures are increasing due to electric environmental factors such as surge and noise in industrial sites, but it is difficult to identify the cause and design countermeasures.

As the breakdown of facilities due to transient voltages such as lightning strikes increases along with changes in the electrical environment, high-quality and stable power supply is required, and facilities for constant monitoring and monitoring have been applied to important facilities such as some substations. .

However, these general measuring equipment is a facility of fault recording function to monitor the fault of AC power at 60Hz frequency, which is not suitable for observing transient voltage such as lightning or surge with a very high rise time. There is this.

In addition, it is possible to measure transient voltage transients using equipment such as oscilloscopes. However, this requires a separate expensive voltage probe and has a problem that it is practically inadequate for long-term monitoring of instantaneous data.

In addition, the conventional impulse divider and measuring device has a problem that it is impossible to measure the transient voltage penetrating through the ground meter in the actual field in the common mode (common mode) in which one line is connected to the ground.

In addition, a high-precision measuring device is required for long-term monitoring of transient voltage transients that occur instantaneously with power quality.A power quality analysis device currently applied at home and abroad cannot rapidly measure transient voltage waveforms. In terms of economics, there is a problem that the utilization is very low.

The present invention was devised to solve the above problems, the power for measuring the transient voltage and AC power quality generated in the low-voltage consumer for the analysis of the cause of the failure due to the transient overvoltage, such as surge, noise in the industrial field It is an object to provide a quality measuring system and a divider circuit used therein.

In addition, an object of the present invention is to provide a power quality measuring system and a divider circuit used therein which can improve the economics and utilization by enabling the simultaneous measurement of the transient voltage and the AC voltage generated in the low-voltage consumer.

In addition, the present invention can monitor the transient voltage that can not be measured by the power quality analysis device for a long time, and at the same time to monitor the commercial AC voltage, thereby increasing the utilization and meet the demand of high quality power demand through this. It is an object of the present invention to provide a power quality measuring system and a divider circuit used therein that can improve the reliability of power quality.

According to an aspect of the present invention, there is provided a power quality measurement system comprising: an input unit including an impulse divider for measuring an impulsive transient voltage, and an alternating divider for measuring an AC voltage; And an A / D converter for measuring an impulse voltage for sampling the signal measured by the impulse divider, an A / D converter for measuring an AC power supply for sampling the signal measured by the AC divider, and an A / D for measuring the impulse voltage And a signal processing unit having a converter and a controller for processing a signal output from the AC power measurement A / D converter.

Here, the input unit preferably further includes a signal regulator for linearizing the signal measured by the impulse divider and the AC divider.

In addition, the impulse divider and the AC divider is preferably implemented to simultaneously measure the impulsive transient voltage and the AC voltage.

Preferably, the impulse divider and the AC divider are divided into a high voltage portion and a low voltage portion divided according to the voltage partial pressure ratio.

In addition, it is preferable that an inductor and a resistor are inserted in series between the high voltage portion and the low voltage portion.

Preferably, the high-pressure portion is a cylindrical carbon film-type resistor, an insulating film surrounded by the resistance to insulate, a conductive metal film surrounding the insulating film and electrically bonded to one side lead of the resistor, the resistance and the insulating film and And a cylindrical insulating tube into which the conductive metal film is inserted, and a second conductive film surrounding the outside of the insulating tube and bonded to the other lead wire of the resistor.

In addition, the low voltage unit preferably includes a low pass filter for removing the impulse voltage.

In addition, the control unit preferably includes a processor using a field programmable gate array (FPGA).

A divider circuit according to the present invention for achieving the above object, an impulse divider for measuring an impulsive transient voltage; And an AC divider for measuring an AC voltage, wherein the impulse divider and the AC divider are each characterized by simultaneously measuring an impulsive transient voltage and an AC voltage.

Here, the impulse divider and the AC divider may be divided into a high voltage portion and a low voltage portion divided by the voltage divider ratio.

In addition, it is preferable that an inductor and a resistor are inserted in series between the high voltage portion and the low voltage portion.

Preferably, the high-pressure portion is a cylindrical carbon film-type resistor, an insulating film surrounded by the resistance to insulate, a conductive metal film surrounding the insulating film and electrically bonded to one side lead of the resistor, the resistance and the insulating film and And a cylindrical insulating tube into which the conductive metal film is inserted, and a second conductive film surrounding the outside of the insulating tube and bonded to the other lead wire of the resistor.

In addition, the low voltage unit preferably includes a low pass filter for removing the impulse voltage.

As a result, the power quality measuring system and the divider circuit used in the present invention have a high-accuracy impulse voltage divider for measuring a transient voltage (minimum rise time 50ns, maximum voltage 20kV) having a very fast rise time without waveform distortion. The voltage divider can be implemented and used to monitor the power quality for a long time.

In addition, the power quality measuring system according to the present invention and the divider circuits used therein are used to measure the transient voltage and AC power quality generated in the low voltage consumer to analyze the cause of the failure due to the transient overvoltage such as surge and noise in the industrial field. It becomes possible to measure.

In addition, the power quality measurement system according to the present invention and the divider circuit used therein can improve the economics and utilization by enabling simultaneous measurement of the transient voltage and the alternating voltage generated at the low voltage consumer.

In addition, the power quality measurement system according to the present invention and the divider circuit used therein, can monitor the transient voltage that can not be measured by the power quality analysis device for a long time, and at the same time to monitor the commercial AC voltage, In this way, it is possible to improve the reliability of power quality for the times when high quality power demand is required.

Hereinafter, a power quality measurement system and a divider circuit used therein will be described in detail with reference to the accompanying drawings.

1 is a view schematically showing the configuration of a power quality measurement system according to the present invention. Referring to the drawings, the power quality measurement system includes an input unit 100 and a signal processor 200.

Here, the input unit 100 includes an impulse divider 110 for measuring an impulsive transient voltage, an AC divider 120 for measuring an alternating current (AC) voltage, and an impulse divider 110 and an AC divider 120. And a signal conditioner 130 to linearize the signal measured by < RTI ID = 0.0 > The signal conditioner 130 provides an impulse divider 110 to provide the required accuracy, resolution, and repeatability for the signals measured from the impulse divider 110 and the alternating divider 120. And linearize the signal measured from the AC divider 120.

In addition, the signal processing unit 200 is an AC power measurement for sampling the signal measured by the impulse voltage measurement A / D converter 210 for sampling the signal measured by the impulse divider 110, the AC divider 120 A / D converter 220, and an A / D converter 210 for measuring an impulse voltage, and a controller 230 for processing signals output from the A / D converter 220 for measuring AC power. In addition, the signal processor 200 may include a display 240 for displaying a result processed by the controller 230, a key switch 250 for receiving a command by an administrator, and an interface for transmitting and receiving data through a network ( 260 and the storage unit 270 for storing temporary data for signal processing by the controller 230 may be further provided.

 Surge voltage waveforms, including brain impulses, have very fast rise times and include high frequency components in the several MHz band, so the design of the voltage divider is important to accurately measure them. 2 is a divider circuit for simultaneously measuring an impulsive transient voltage and an AC voltage. An impulse voltage divider circuit is designed by combining a capacitor and a resistor to measure an impulse waveform having a very fast rise time of several tens of nsec. It is desirable to configure the differential input method to improve the characteristics and to measure the impulse invading through the ground system.

Referring to FIG. 2, the impulse voltage applied to the input terminal is divided in accordance with the partial pressure ratio into the high voltage unit 112 configured in parallel combination of R _H1 and C _H1 and the low pressure unit 114 composed of R _L1 and C _L1 . In addition, the recent high-speed sampling function A / D converter 210 is limited to very low voltage within a few V, so in order to measure the impulse voltage of several tens of kV, R _H2 , C _H2 and R _L2,. It is necessary to increase the partial pressure ratio by means of a secondary voltage divider composed of C _L2 . In the present invention, by separating the high pressure unit 112 composed of R _H1 , C _H1 to the outside of the measuring device, the measuring device can be compactly designed by considering only the low pressure unit 114 without considering insulation while measuring the high pressure impulse. .

In addition, the connection of the high voltage part 112 and the low pressure part 114 of the divider of the power quality measurement system according to the present invention is connected using a general cable rather than a coaxial cable, and the ground according to the length of the cable and the layout of the cable In order to compensate for the distortion of the measurement waveform caused by the change of capacitance with, it is preferable to insert the inductor Ldamp and the resistor Rdamp in series. In this case, the inductance is calculated to be sufficiently larger than the cable length in consideration of the length of the cable, and the influence of the measurement waveform due to the insertion of the cable can be eliminated. The resistance serves to suppress the over vibration of the waveform.

3 illustrates a schematic diagram of a resistor and a capacitor constituting the high voltage part 112. In the present invention, the capacitance of the geometric structure according to the arrangement of the conductors is used as the capacitor of the high voltage part 112. Referring to FIG. Unlike a coaxial cable, when measuring voltage using a normal cable, the capacitance with the earth changes according to the cable layout, which causes distortion in the rapidly changing transient voltage waveform. Therefore, in order to reduce the error due to the capacitance change, a capacitor having a capacity sufficiently larger than the capacitance of the cable and the ground is required in the high voltage unit 112 of the divider. When the capacitor is applied, the larger the capacitance, the smaller the measurable frequency band. Therefore, this should be taken into account to measure the high frequency signal.

이라 하면 커패시턴스는 일반 원통형 구조의 커패시턴스를 구하는 방법과 동일하게 다음 수학식 1과 같이 계산된다.The high pressure part 112 of the divider according to the present invention is composed of a high-pressure carbon film-type resistor 113, an insulating film 115, conductive films 117, 119, and a cylindrical insulating tube 118. First, the cylindrical resistor 113 is insulated with the insulating film 115, and then the conductive metal film 117 is surrounded by the upper resistor 113 and electrically bonded to one lead wire A of the resistor. The resistor 116 is inserted into the cylindrical insulating tube 118, and the conductive film 119 is enclosed again outside the insulating tube as shown in FIG. 3 and bonded to the other resistance lead wire B. FIG. In this configuration, as shown in FIG. 4, the capacitor is geometrically configured by an inner and outer conductive film with a cylindrical insulating tube interposed therebetween. The capacitor is also connected in parallel with the internal cylindrical resistor. The dielectric constant of the insulating tube in Figure 4

In this case, the capacitance is calculated as in Equation 1 in the same way as to obtain the capacitance of a general cylindrical structure.

In this way, high-precision high voltage capacitors can be manufactured and high-voltage dividers can be designed with uniform field distribution.

5 is a waveform measured when a square wave is applied to an impulse voltage divider, and shows a very fast response characteristic with a rise time of 30 ns or less.

On the other hand, since the AC voltage is relatively small compared to the impulse, the partial pressure ratio should be different for accurate measurement. In the present invention, the low voltage part is composed of R _L as shown in FIG. 2. In addition, the AC voltage measuring unit removes the impulse voltage by using a low pass filter composed of R _f and C _f to protect the device connected to the rear end from overvoltage and detect only stable AC signal.

In this manner, the divided impulse voltage and the AC voltage are input to the A / D converters 210 and 220 through the signal conditioning circuit 130 composed of Op-Amps, respectively. The A / D converter 210 for measuring the impulse voltage can measure a high impulse by sampling at a high speed, and the A / D converter 220 for measuring the AC power selects a sampling period suitable for measuring AC power at a commercial frequency of 60 Hz. do.

For high-speed processing of the converted digital signal, a high-speed signal processing processor is implemented using a field programmable gate array (FPGA) device.

6 is an internal configuration diagram of an FPGA and includes a clock generator using an internal phase locked loop (PLL) 231 to supply a clock frequency for signal conversion to an A / D converter. In addition, the bus controller 234 and 235 circuit is configured to transmit measured data to an external memory using a tri-state buffer bus and to be connected to a system controller 236 based on a digital signal processing (DSP).

Since it is difficult to predict when an impulse transient voltage resulting from lightning, etc., will occur, the measurement device should always be in standby state and data should be acquired when a trigger event occurs. As a trigger algorithm for this, a method of comparing the average of sampled data is applied to detect only a surge signal excluding a noise component from a signal flowing into a measuring instrument. As shown in FIG. 7, N is sampled from a period of T ₀ to T _n , averaged, and then compared with an average value of T ₁ to T _{n + 1} to detect whether a transient voltage is generated as a difference in change rate. That's the way. In particular, the transient voltage generated on the power line is always superimposed on the voltage of the commercial frequency, so when applying this algorithm, it is possible to reduce the influence on noise and improve the accuracy of the measurement, compared to the trigger method based on the conventional simple magnitude comparison. Can be. To this end, it consists of a Trigger Detector circuit using a high-speed Shift computation processor with a pipeline structure in the FPGA.

In addition, in the present invention, as shown in FIG. 8, the dividers 110 and 120, the A / D converters 210 and 220, and the FPGA-based signal processor 230 are configured on the input boards for each channel. Use the main control board. The main control board performs FPGA control and memory management, measurement data storage (SD card control), and user interface (Display, Input-Keypad) control when a trigger event occurs.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention without departing from the spirit of the present invention as claimed in the claims. Anyone skilled in the art can make various modifications, as well as such modifications are within the scope of the claims.

1 is a view schematically showing the configuration of a power quality measurement system according to the present invention.

FIG. 2 is a diagram schematically illustrating a configuration of a divider circuit used in the power quality measurement system of FIG. 1.

3 is a view for explaining the configuration of the high-pressure section of the divider.

4 is a cross-sectional view illustrating the divider high voltage part of FIG. 3.

5 is a diagram illustrating a response waveform of an impulse divider with respect to a square wave input.

6 is a diagram schematically illustrating a configuration of an FPGA-based signal processor.

7 is a diagram illustrating a trigger algorithm.

8 is a diagram schematically showing the configuration of a DSP controller and a multichannel measurement system.

Description of the Related Art

100: input unit 110: impulse divider

120: AC divider 200: signal processing unit

210: A / D converter for measuring impulse power

220: A / D converter for measuring AC power

230: control unit

Claims (13)

An input unit having an impulse divider for measuring an impulsive transient voltage, and an AC divider for measuring an AC voltage; And An impulse voltage measurement A / D converter for sampling the signal measured by the impulse divider, an AC power measurement A / D converter for sampling the signal measured by the AC divider, and the A / D converter for measuring the impulse voltage And a signal processing unit including a control unit for processing a signal output from the AC power measurement A / D converter. The method of claim 1, wherein the input unit, And a signal conditioner for linearizing the signals measured by the impulse divider and the alternating divider. The method according to claim 1 or 2, And the impulse divider and the AC divider measure an impulsive transient voltage and an AC voltage simultaneously. The method according to claim 1 or 2, The impulse divider and the AC divider is a power quality measurement system, characterized in that divided into a high voltage portion and a low voltage portion divided by the voltage divider ratio. The method of claim 4, wherein An inductor and a resistor are inserted in series between the high voltage section and the low voltage section. The method of claim 4, wherein the high pressure portion, Cylindrical carbon film-type resistor, an insulating film surrounded by the resistance to insulate, a conductive metal film surrounding the insulating film and electrically bonded to one side lead of the resistor, the cylindrical with the resistor and the insulating film and the conductive metal film is inserted And a second conductive film surrounding the outside of the insulating tube and bonded to the other lead of the resistor. The method of claim 4, wherein The low voltage unit is a power quality measurement system, characterized in that it comprises a low pass filter for removing the impulse voltage. The method according to claim 1 or 2, The control unit includes a processor using a field programmable gate array (FPGA). An impulse divider for measuring impulsive transient voltages; And AC divider for measuring AC voltage, And said impulse divider and said alternator divider simultaneously measure an impulsive transient voltage and an alternating voltage, respectively. The method of claim 9, The impulse divider and the AC divider circuit is divided into a high voltage portion and a low voltage portion divided by the voltage divider ratio. The method of claim 10, A divider circuit, wherein an inductor and a resistor are inserted in series between the high voltage section and the low voltage section. The method of claim 10, wherein the high pressure portion, Cylindrical carbon film-type resistor, an insulating film surrounded by the resistance to insulate, a conductive metal film surrounding the insulating film and electrically bonded to one side lead of the resistor, the cylindrical with the resistor and the insulating film and the conductive metal film is inserted And a second conductive film surrounding the outside of the insulating tube and bonded to the other lead wire of the resistor. The method of claim 10, The low voltage unit includes a low pass filter for removing an impulse voltage.

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