KR101608964B1 - A distribution board, motor control panel and cabinet panel with a detecting system for condition using ultra-sonic and TEV probes - Google Patents

Abstract

The present invention relates to a high voltage panel, a low voltage panel, a panel board, and a motor control center with a condition monitoring diagnostic system based on ultrasonic waves and transient earth voltage (TEV), which can diagnose the arc or corona discharge state of a housing having an incoming panel, a switchboard, the motor control center, the high voltage panel, the low voltage panel, and the panel board inside, comprise: a sensor unit consisting of a plurality of ultrasonic sensors installed to be in contact with or near power equipment provided in the housing to detect ultrasonic waves generated by the arc or corona discharge and a TEV sensor provided outside the housing or the power equipment to detect TEV generated by the arc or corona discharge; and a monitoring device including an abnormality determination unit for detecting the arc or corona discharge generated outside the power equipment by using the ultrasonic signals detected by the sensor unit, detecting the arc or corona discharge generated outside the power equipment or partial discharge generated inside the power equipment by using the TEV detected by the sensor unit, and controlling the internal state of the housing according to the detected arc or corona discharge and partial discharge information. Therefore, the system of the present invention can detect the arc or corona discharge of 40 kHz band, which is generated outside the power equipment, by using the ultrasonic signals and can detect both the arc or corona discharge of 40 kHz or higher, which is generated outside the power equipment, and the partial discharge, which is generated inside the power equipment, by using the TEV detected by the TEV sensor.

Description

Technical Field [0001] The present invention relates to a high-voltage, low-voltage, distribution board, motor control panel, and a motor control panel and a diagnosing system using condition monitoring diagnosis system based on ultrasound and transient ground voltage,

The present invention relates to a water turbine, an electric distribution panel, an electric motor control panel, and a power control panel using an ultrasonic signal generated by an ultrasonic sensor installed in a housing of a switchgear and a transient earth voltage generated by a transient earth voltage (TEV) A high pressure chamber equipped with an arc or corona due to connection failure or disconnection in a housing including a high pressure chamber, a low pressure chamber and a distribution panel inside, and an ultrasonic wave and transient ground voltage based condition monitoring diagnosis system for detecting occurrence of a partial discharge , A low-pressure panel, a distribution panel, and a motor control panel.

In particular, the present invention uses an ultrasonic signal detected by an ultrasonic sensor to sense an arc or a corona discharge in a 40 kHz band generated outside the electric power facility, and detects an arc or corona discharge in the 40 kHz band by using a transient ground voltage detected by a TEV sensor. Pressure panel, a distribution panel, and a motor control panel equipped with a state monitoring diagnostic system based on an ultrasonic wave and an excessive ground voltage for detecting an arc or corona discharge of 40 kHz or more generated in the power plant and a partial discharge occurring in the electric power plant .

Electricity demand is continuously increasing due to the advancement of the industry, and accidents caused by electric power facilities in the switchboard are frequently occurring. Such accidents can cause technical losses as well as economic losses.

Generally, the surrounding insulating material is oxidized and pyrolyzed by the arc discharge of the internal line due to the contact point in the switchboard or the vibration and shock generated in the operation of the transformer, thereby forming the carbonized conductive path. As a result, electrons move around the carbonized conductive path to generate a short circuit, which causes a decrease in the dielectric strength, resulting in an accident such as electric fires or electric shocks.

In addition, various kinds of insulators are used in the installation devices inside the switchgear to prevent discharge phenomena such as corona, partial discharge, flashover, etc. occurring in a high voltage situation. However, such insulation may cause gaps such as voids or delaminations during cooling and heating during operation for some reason or during operation. However, such a gap generates a partial electric discharge every time a high electric field is applied, and if such a partial discharge is repeated, the insulation is gradually eroded and the dielectric strength is reduced, resulting in serious dielectric breakdown. In order to solve this problem, it is desirable to remove the gap in the insulating material in advance to reduce the occurrence of partial discharge, but it is difficult to completely remove the gap in consideration of various reasons. In addition, the insulation characteristics of the insulator must be sufficiently inspected from the time of manufacture. Such inspections are effective for inspection of initial manufacturing defects, but insulative deterioration over time occurs during the operation of the switchboard, so that substantial inspection is difficult. Therefore, in the past, the time interval between inspections increases, and it is impossible to accurately grasp the insulation characteristic at all times, resulting in an unexpected serious accident. In addition, the deterioration can be monitored by measuring the partial discharge.

Therefore, various inspection technologies have been developed to prevent accidents in the switchboard. For example, there has been proposed an electromagnetic wave detection method in which an electromagnetic wave radiated at the time of insulation deterioration is measured to check whether or not there is an abnormality in the switchboard. The conventional electromagnetic wave detection method detects electromagnetic waves in the VHF and UHF bands in the frequency range of 30 Hz to 300 MHz and 300 MHz to 3 GHz in most cases and exhibits high resonance and sensitivity. However, it is easily influenced by vibration and external disturbance, This is difficult. In addition, conventionally, it can not be confirmed whether the initial installation environment and setting of the electromagnetic wave receiving antenna have changed due to vibrations and dust generated in the switchgear, the motor control panel, and the panel board, and the change in the internal environment of the switchgear, Can not be confirmed.

Therefore, conventionally, it is impossible to prevent the occurrence of malfunction of the electromagnetic wave receiving antenna due to the change of the installation environment. To this end, technologies for monitoring and diagnosing arc and corona discharges through non-contact composite sensors, electromagnetic waves or ultraviolet ray detection have been proposed (Patent Documents 1 and 2).

On the other hand, when electricity flows around the high-voltage line or the defective portion of the electrical connection portion of the low-pressure portion, the surrounding air molecules are disturbed and the ultrasonic wave is generated by the collision of the air molecules due to the disturbance of the air. Often these sounds are often perceived as crackling or popping, and they sound like a buzzer.

Ultrasonic detection can identify various types of potential electrical failures, especially electrical failures such as arcing, corona, and tracking. In addition, electrical faults are not only costly for fire and power outage, but can also be extremely fatal to the human body. Therefore, there is a great need to accurately detect the occurrence of an accident. In addition, when a discharge phenomenon such as an arc or a corona occurs in a high-voltage electric power facility, it causes not only various troubles but also a fatal result to the human body. Therefore, in order to prevent accidents and failures, Needs to be.

The main reason that the ultrasonic measurement is noticed is that the measuring device is relatively simple, so it is easy to apply in the field, and it does not cause the electric measuring method and mutual interference. Also, the electrostatic capacity and the external noise As well.

It is well known that when an arc or a corona discharge occurs in a distribution line or an indoor or outdoor power device, acoustic energy is emitted by the discharge. Particularly, corona discharge is an unavoidable phenomenon in outdoor power equipment which uses air as insulation, though there is a difference in scale depending on the structure of the conductor, the magnitude of the applied voltage, and the weather condition. Particularly, it can be seen that the starting voltage of the corona is lowered when the conductor and the insulator supporting the conductor are dirty or rainy, and the discharge noise is large. When an arc or a corona discharge occurs in a high-voltage power facility, it causes not only various troubles but also rapid deterioration of the surrounding insulation, resulting in breakdown of the insulation. Therefore, it is necessary to continuously monitor the progress of such arc or corona discharge during operation in order to prevent the device from failing.

The ultrasonic diagnosis method can detect the arc or corona discharge phenomenon generated in the high-voltage and low-voltage equipment and can be applied to the prevention diagnosis of the insulation breakdown accident [Patent Literatures 3,4,5]. Ultrasonic diagnosis methods reported in domestic and foreign countries are mostly applied to electric power transformers or capacitors using dielectric oil or liquid dielectric as a transmission medium, but ultrasonic diagnosis methods are applied in air as well as deterioration diagnosis of solid insulators . Since about 99% of the acoustic energy generated by the arc or corona discharge in the air is emitted from the ultrasonic wave region, a method for prevention diagnosis of high voltage devices using air ultrasonic waves is highly expected.

Korean Patent No. 10-1232750 (Announcement of Mar. 23, 2013) Korean Registered Patent No. 10-1232739 (Announcement of Mar. 23, 2013) Korean Patent No. 10-0900245 (issued on May 29, 2009) Korean Patent No. 10-1077441 (issued October 26, 2011) Korean Patent Publication No. 10-2011-0070969 (published on June 27, 2011)

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an ultrasonic diagnostic apparatus and a method for detecting an ultrasonic signal by means of an ultrasonic sensor installed in a housing of a switchgear and a transient earth voltage (TEV) Based on the ultrasonic wave and the transient ground voltage based on detection of occurrence of an arc or corona due to poor connection or disconnection in a housing including a water tank, a distribution board, an electric motor control board, a high pressure tank, a low pressure tank, A high-pressure panel, a low-pressure panel, a distribution panel, and a motor control panel equipped with a monitoring diagnostic system.

It is another object of the present invention to provide a power supply apparatus and a power supply apparatus capable of detecting an arc or a corona discharge in a 40 kHz band generated outside an electric power facility by using an ultrasonic signal detected by an ultrasonic sensor, A high-voltage panel, a low-voltage panel, a distribution panel, and a motor control panel equipped with an ultrasonic wave and a transient ground voltage based condition monitoring diagnosis system for detecting an arc or corona discharge of 40kHz or more generated in the outside of the power plant, .

It is another object of the present invention to provide an FIR filter that measures an ultrasonic signal when a discharge is not detected by an excessive ground voltage, extracts a cutoff frequency, constructs an FIR filter using the cutoff frequency, Pressure panel, a distribution board, and a motor control panel equipped with a state monitoring diagnostic system based on an ultrasonic wave and an excessive ground voltage for detecting whether an arc or a corona discharge is generated by removing noises through the noise.

In order to accomplish the above object, the present invention provides a method of diagnosing a state of discharge or partial discharge of an arc or a corona of a housing including a water turbine, an electric distribution board, a motor control panel, a high pressure disk, a low pressure disk, Pressure panel, a power distribution board, and a motor control panel, which are mounted in contact with or close to a power facility provided inside the housing, and which detect ultrasonic waves generated by arc or corona discharge, And a TEV sensor provided outside the housing or the electric power facility and configured to detect a transient earth voltage (TEV) generated by an arc, a corona discharge, and a partial discharge; And an ultrasonic sensor for sensing an arc or a corona discharge occurring outside the electric power facility using the ultrasonic signal detected by the sensor unit and detecting an arc or a corona generated outside the electric power facility using the transient ground voltage detected by the sensor unit, And a surveillance device for detecting an electric discharge and a partial discharge occurring in the electric power facility and controlling an internal state of the housing in accordance with the detected arc or corona discharge and partial discharge information .

Further, the present invention is characterized in that the ultrasonic wave generated from the ultrasonic sensor in the frequency range of 30 kHz to 48 kHz is measured in a high-pressure panel, a low-pressure panel, a distribution panel, and a motor control panel equipped with a state monitoring diagnostic system based on ultrasound and transient ground voltage do.

Further, the present invention provides a high-voltage switch, a low-voltage switch, a distribution board, and a motor control board mounted with a state monitoring diagnostic system based on ultrasonic and transient ground voltages, wherein the abnormality determination unit determines that the transient ground voltage Detecting a background noise ultrasound signal through the ultrasonic sensor to detect a frequency greater than a predetermined minimum noise level in the ultrasound signal of the background noise when the measured ultrasound signal is less than a predetermined minimum reference value, And an ultrasound signal of an arc or a corona discharge is detected through the ultrasonic sensor when the transient ground voltage is measured by the TEV sensor to be equal to or greater than a predetermined minimum reference value, The noise of the ultrasonic signal is suppressed through the FIR filter designed for the ultrasonic signal of the arc or corona discharge. And detecting whether an arc or a corona discharge from the detected transient voltage and ground, noise is removed, the ultrasonic signal, or characterized in that for determining the type of discharge.

Further, the present invention provides a high-voltage panel, a low-voltage panel, a distribution panel, and a motor control panel on which a state monitoring diagnostic system based on ultrasound and transient ground voltage is mounted, wherein the abnormality determination unit sets a range of cutoff frequencies in advance, Extracts a cutoff frequency within the range of the cutoff frequency, and when it is not possible to detect within the range of the cutoff frequency a frequency larger than a predetermined minimum noise size in the background noise ultrasonic signal, .

According to another aspect of the present invention, there is provided a high-voltage panel, a low-voltage panel, a distribution panel, and a motor control panel on which a state monitoring and diagnosis system based on ultrasonic waves and transient ground voltage is mounted, wherein the abnormality determination unit extracts a peak of discharge from the ultrasonic signal, At least two or more of the average size, the peak number of peaks per unit time, and the average interval of peaks are defined as characteristic values, and the type of discharge is classified using the characteristic values.

In addition, the present invention provides a high-voltage, low-voltage, distribution board, and motor control board on which a state monitoring and diagnosis system based on ultrasonic and transient ground voltages is mounted, wherein the abnormality determination unit calculates n-time ultrasonic signals e (n) is larger than a predetermined peak ratio in comparison with the size of the moving average filter F (n), the moving average filter F (n) for the n-time ultrasonic signal e (n) is determined as a peak.

[Equation 1]

Here, e (n) is an ultrasonic signal of n time, and L is a predetermined value as a length of a filter section of the moving average filter.

In addition, the present invention provides a high-voltage, low-voltage, distribution board, and motor control board having a state monitoring and diagnosing system based on ultrasonic waves and transient ground voltage, wherein the abnormality determination unit includes an LF-FIR The HF-FIR filter is obtained from the LF-FIR filter using the following equation (2), and the filter coefficient h (HF-FIR) of the LF- ₁ [n] is obtained by the following [Expression 3].

[Equation 2]

Where h _high [n] is the impulse response of the HF-FIR filter, h _low [n] is the impulse response of the LF-FIR filter, and n is an integer.

[Equation 2]

Where f _c is the cutoff frequency, and f _s is the sampling frequency.

According to another aspect of the present invention, there is provided a high-voltage panel, a low-voltage panel, a distribution panel, and a motor control board mounted with a state monitoring and diagnosis system based on ultrasonic waves and transient ground voltage, wherein the ultrasonic sensor comprises a frequency mixing circuit and a local oscillation circuit, A frequency converter for dropping the signal to an intermediate frequency; An amplifying unit for amplifying the intermediate frequency; And a demodulator for separating an original signal of an audible frequency from the amplified signal. The ultrasonic sensor uses a power supply line and a signal line together and forms an inverse coupling circuit for detecting only acoustic signals included in the power supply, The inverse coupling circuit comprises first and second capacitors connected in parallel between the power source and the ground and a first conductor connected in series between the first and second capacitors to remove high frequency noise included in the power source .

The TEV sensor has a resistance R _m , a capacitance C _d , and an inductance L _d in series. The resistance R _m , the capacitance C _d , and the inductance L _d are connected in series to each other. And a coupling network having a coupled detection impedance and an input impedance R _i of the amplifier connected in parallel with the inductance L _d .

As described above, according to the high-voltage, low-voltage, distribution board, and motor control boards equipped with the ultrasound and transient ground voltage based condition monitoring diagnosis system according to the present invention, The arc or corona discharge is detected, and an arc or corona discharge of 40 kHz or more band generated outside the electric power facility using the transient ground voltage detected by the TEV sensor and a partial discharge occurring in the electric power facility can be detected Effect is obtained.

In addition, according to the present invention, in the high-voltage, low-voltage, distribution board, and motor control boards equipped with the ultrasound and transient ground voltage based condition monitoring and diagnosis system, ultrasound signals of background noise are detected using the transient ground voltage, By removing the noise mixed with the ultrasonic signal by the FIR filter and classifying the discharge type by the discharge peak, it is possible to perform the discharge detection with more accurate and reliable not only the discharge but also the type of discharge.

1 is a block diagram of a configuration of a high-voltage, low-voltage, distribution board, and motor control board equipped with a state monitoring and diagnosis system based on ultrasound and transient ground voltage according to an embodiment of the present invention.
2 is a structural view of an ultrasonic sensor according to an embodiment of the present invention.
3 is a configuration diagram of an ultrasonic transmission circuit according to an embodiment of the present invention;
4 is a configuration diagram of a power supply circuit according to an embodiment of the present invention;
5 is a configuration diagram of an oscillation circuit according to an embodiment of the present invention;
6 is a circuit configuration diagram of an inverting buffer according to an embodiment of the present invention;
7 is a circuit configuration diagram of a transducer driver according to an embodiment of the present invention;
8 is a circuit diagram of an inverse coupling circuit according to an embodiment of the present invention and a graph of the frequency response characteristic thereof.
9 is a circuit configuration diagram of an input unit according to an embodiment of the present invention;
10 is a circuit diagram of an amplifying circuit according to an embodiment of the present invention and a graph of a frequency response characteristic thereof.
11 is a circuit configuration diagram of a frequency conversion circuit according to an embodiment of the present invention.
12 is a circuit diagram of a band-pass filter according to an embodiment of the present invention;
FIG. 13 is a view showing a positional arrangement of an ultrasonic sensor according to an embodiment of the present invention; FIG.
FIG. 14 is an exemplary view for explaining the principle of detection of a transient ground voltage according to the present invention; FIG.
15 is a structural view of a transient ground voltage on the surface of a switchgear housing according to the present invention.
16 is an exemplary graph of a waveform of a transient ground voltage for an arc discharge according to the present invention.
17 is a graph showing the magnitude of transient ground voltage versus time delay according to the present invention.
18 is a circuit diagram of a probe of a TEV sensor according to the present invention.
19 is an exemplary diagram illustrating the configuration of a TEV measurement system according to the present invention.
20 is a structural view of a capacitive probe of a TEV sensor according to the present invention.
21 is an equivalent circuit diagram of a coupling circuit of a TEV sensor according to the present invention.
22 is a graph of a frequency response characteristic of a coupling circuit and an amplifier of a TEV sensor according to the present invention.
23 is a graph of a frequency response characteristic of a band pass filter according to the present invention.
24 is a block diagram of a configuration of a monitoring apparatus according to an embodiment of the present invention;
25 is a block diagram of a configuration of an abnormality determination unit according to an embodiment of the present invention;
26 is a graph showing a representative frequency spectrum distribution of a corona discharge according to an embodiment of the present invention.
27 is a representative frequency spectrum distribution graph of an arc discharge according to an embodiment of the present invention.
FIG. 28 is a graph of a corona discharge frequency band according to an embodiment of the present invention. FIG. 28 (a) is an ultrasonic signal [100 mV / div, 10 ms / ) [2.0 mV / div, 10 kHz / div].
FIG. 29 is a graph of a carbon-copper electrode arc discharge frequency band according to an embodiment of the present invention. FIG. 29 (a) shows an ultrasonic signal [100 mV / div, 10 ms / A graph for the spectrum (Frequency spectrum) [2.0 mV / div, 10 kHz / div].
30 is a diagram illustrating a data storage method for applying an FIR filter according to an embodiment of the present invention.
31 is a graph of a normal waveform ultrasonic signal according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

In the description of the present invention, the same parts are denoted by the same reference numerals, and repetitive description thereof will be omitted.

First, a configuration of a high-pressure panel, a low-voltage panel, a distribution panel, and a motor control panel mounted with an ultrasonic transient monitoring system and a transient grounding voltage based condition monitoring system according to an embodiment of the present invention will be described with reference to FIG.

1, a power control panel such as a high-pressure panel, a low-voltage panel, a distribution panel, a motor control panel, and the like mounted with the ultrasonic transducer and the transient ground voltage based condition monitoring and diagnosis system is installed in the switchgear housing 10 A sensor unit 20, a monitoring device 30, and a remote server 40. In addition, it may further comprise a load factor monitoring device 50 for monitoring the load factor of the monitoring device 30. [ The load factor is obtained as a percentage of the current load power versus the capacity of the transformer.

The sensor unit 20 includes a plurality of ultrasonic sensors 21 and a TEV (Transient Earth Voltage) sensor 22. The ultrasonic sensor 21 measures the ultrasonic waves generated by the arc or the corona discharge by contacting or in close proximity to the power equipment 11 provided inside the powerhouse 10. Further, the TEV sensor 22 is installed in the switchgear housing 10 to measure the surface current caused to the outside of the electric power facility 11 by discharge. At this time, the TEV sensor 22 can measure the surface current caused by the arc and corona discharge generated outside the electric power facility 11, and also can measure the electric current caused by the partial discharge generated inside the electric power facility 11 Can be measured. Therefore, the TEV sensor 22 can detect not only the arc / corona discharge but also the partial discharge.

The ultrasonic sensor 21 is a sensor that senses ultrasonic waves due to arc or corona discharge of a component or power facility 11 in a switchgear housing including a high voltage device such as a busbar, a breaker, MOF, CT, PT and a transformer . Particularly, the ultrasonic sensor 21 is installed at a facility site where insulation or discharge is expected in the interior of the switchgear housing 10 so that ultrasonic waves generated by arc or corona discharge of the electric power facility 11 provided in the interior of the switchgear housing 10 Measure the signal. Therefore, it is possible to grasp the position where the arc or corona discharge is generated by the plurality of ultrasonic sensors 21, and to analyze the waveform pattern of the ultrasonic waves, and to know the kind of arc or corona discharge. However, there are cases where the ultrasonic waves are mixed with a lot of noise depending on the condition of the surrounding environment or the inside of the housing, so that the accurate arc or corona discharge can not be detected.

On the other hand, when arc or corona discharge occurs inside the housing 10 of the switchgear, high-frequency electromagnetic waves due to the discharge occur on the surface of the metal wall, causing a surface current. The TEV sensor 22 is mounted on the outer surface of the power plant 11 or the power housing 11 to detect a pulse voltage (transient ground voltage signal). Therefore, the TEV sensor 22 can not determine the position where the arc or corona discharge is generated, but can accurately detect the occurrence of arc or corona discharge. Also, the TEV sensor 22 can measure the current caused by the partial discharge generated therein. Therefore, the TEV sensor 22 can detect not only the arc / corona discharge but also the partial discharge.

In addition, the power control panel, such as a power distribution panel, is installed in a building or a factory using a large amount of electric power. The power control panel is divided into a water main panel, an electric distribution panel, and a distribution panel according to its use. Various power facilities 11 for supplying power are installed. The equipment or the equipment 11 installed in the interior of the switchgear housing 10 can be installed in a variety of ways such as a bus bar, a vacuum breaker VCB, a power transformer PT, a power meter, a load break switch (LBS) Various mold-type insulation devices, component connecting parts, and components for which insulation deterioration prediction is required. For example, it is needless to say that the discharge diagnosis system of the present invention can be applied as a device for monitoring facilities such as a molded case circuit breaker (MCCB) and various distribution lines, which are low-voltage side constituent devices inside a switchgear.

The discharge diagnosis system for a switchgear according to the present invention is provided with a sensing means for sensing the state of each device in the housing 10 to detect a discharge or a deterioration state through the discharge of the switchgear.

Meanwhile, the sensor unit 20 and the monitoring device 30, the monitoring device 30, and the remote server 40 are connected by a network to perform data communication. Preferably, the sensor unit 20 and the monitoring device 30 are connected to the Internet by the UDP protocol, and the monitoring device 30 and the remote server 40 are connected to the Internet by the TCP protocol.

Next, the monitoring apparatus 30 receives the ultrasonic signal or the excessive ground voltage (or pulse voltage) signal sensed from the sensor unit 20, and analyzes the received ultrasonic wave and the pulse voltage to determine the abnormality of the switchboard. The monitoring apparatus 30 monitors the discharge state in the area inside the housing 10 or each facility 11 and compares the discharge state with the reference ultrasonic signal pattern (ultrasonic signal pattern at the time of the discharge phenomenon) It is judged whether there is abnormality. In addition, the monitoring device 30 displays the measured discharge state of the inside or the equipment on the display as an image, or notifies the manager of the detection of the abnormality when the abnormality is detected.

That is, the monitoring device 30 detects a discharge state, a partial discharge, or a deterioration state through the inside of the housing, based on an ultrasonic signal of an internal area detected by the sensor unit 20, an excessive ground voltage, And controls the internal state of the housing or generates an alarm signal according to the discharged or deteriorated state information in the diagnosed housing.

Preferably, the monitoring device 30 may be attached to the housing 10 of the switchgear. For example, the sensor unit 20 can be installed in the interior of the switchgear housing 10 or attached to each facility 11, and the monitoring device 30 can be installed outside the switchgear housing 10. At this time, an ultrasonic signal from the inside or the equipment is acquired from the ultrasonic sensor 21 installed inside, the transient ground voltage signal is obtained from the TEV sensor 22 installed outside the housing or the facility, and the monitoring device 30 measures the ultrasonic signal Signal and the TEV signal to determine whether there is an abnormality in the housing 10 of the switchgear.

The remote server 40 is a device having a computing processing function such as a personal computer (PC) or a server device and is connected to the monitoring device 30 via a network to detect an ultrasonic signal measured from the monitoring device 30, And judged data on the status.

The remote server 40 can share the role with the monitoring device 30 and can process it. For example, the monitoring device 30 monitors the ultrasound signal and the TEV signal measured in real time to perform only a simple pattern comparison to monitor an abnormality, and the remote server 40 learns past ultrasound pattern data and anomalous results Derives the rule of abnormality according to the temperature, and sets or manages the discharge state pattern and the like. In particular, the remote server 40 has excellent performance such as data storage capacity and computing ability, and the monitoring apparatus 30 may be inferior in performance to the remote server 40 as equipment installed in the field. In consideration of such a difference in performance, the functions between the remote server 40 and the monitoring apparatus 30 can be shared. Hereinafter, it will be described that the monitoring device 30 performs all the above functions.

Meanwhile, the remote server 40 is implemented as a computer system of a central control station equipped with a switchboard, but is not limited thereto, and may be a manager's portable communication device, for example, a smart phone, a PDA, or the like.

Further, the monitoring device 30 is connected to the load factor monitoring device 50 to monitor the load factor.

Next, the structure of the ultrasonic sensor 21 according to the present invention will be described with reference to Figs. 2 to 13. Fig.

The ultrasonic sensor 21 is a sensor for detecting an ultrasonic signal. The properties of ultrasonic waves with shorter wavelengths, the nonlinear nature of air, and the introduction of two signals into a nonlinear mixer result in two new additional signals. Sounds that can be heard by human ears can be controlled to spread out in a single direction like a laser beam, while sound waves spread in all directions because of their long wavelengths. Because ultrasound is a sound wave of about 20KHz or more and can not be perceived as sound by the human ear, it is dropped by the intermediate frequency of the constant frequency through the frequency converter to convert it into the audible frequency that a person can perceive as sound, Take the selectivity and detect again.

When two ultrasonic frequencies with sufficiently large amplitudes are in contact with the air, due to the nonlinear nature of the air, both the summed frequency and the subtracted difference frequency result in addition to the original two frequencies.

The high-frequency amplifier stage consists of an input circuit and an amplifier circuit for matching inputs, and the frequency converter is composed of a frequency mixing circuit and a local oscillator circuit. The intermediate frequency amplifier amplifies the input signal. The demodulator is a circuit that separates the original signal of the audible frequency from the signal input.

The following equation expresses an equation for obtaining a gain.

[Equation 1]

Ultrasound emitted from a high-voltage power plant has a characteristic sound that causes the emission of ultrasonic waves as a unique characteristic. Therefore, the ultrasonic waves are converted into audible frequencies, and the ultrasonic waves are analyzed by auditory sense.

The principle of the frequency conversion is as shown in Fig. 2. When two signals f ₁ f ₂ are applied to a diode, a transistor, and an FET having nonlinear characteristics, the sum f ₁ + f ₂ and the difference f ₂ - f ₁ (f ₂ > f ₁ ). The sum and difference signals can be selected by configuring a tuning circuit on the output side.

Such an ultrasonic detector circuit is constructed as shown in FIG. 2 is a diagram showing the principle of frequency conversion. The circuit has been used in the field of preventive diagnosis of electrical equipment since there is no interference with electrical signals. Generally, ultrasonic detectors measure 20 ~ 100kHz band. The frequency range of the arc / corona is spread over a broad band from 30kHz to 150kHz.

Preferably, the corona or arc of the electrical equipment is used to diagnose the deterioration by measuring ultrasonic waves occurring in the 30 kHz to 48 kHz band. At this time, the arc / corona discharge in the 40 kHz band is detected by the ultrasonic sensor 21, and the arc / corona discharge in the 40 kHz or more band besides the 40 kHz band is measured by the TEV sensor 22.

As shown in FIG. 3, the 40 kHz ultrasonic transmission circuit is a 40 kHz multivibrator circuit based on time by the LM555, and the oscillation frequency can be changed by varying the RP resistance. LM555 Ultrasonic signal is emitted from the ultrasonic transducer. The voltage of the circuit is 9V and the operating current is 40 ~ 50mA. The transmitted ultrasound signal should be greater than 8 m.

Preferably, a driver circuit of a stable ultrasonic transducer is constituted as follows by adding a test additional function in the ultrasonic transmission circuit.

First, as shown in Fig. 4, a power supply circuit is constructed. At this time, DC 9V is used to supply power. In particular, the drive power (DRIVE POWER) is DC 18V and the reference power (REFERENCE POWER) is DC 9V.

Next, a 40 KHz oscillation unit is constructed as shown in FIG. Use a negative feedback buffer (INVERTING U1A) to construct a 40KHz crystal oscillator.

As shown in FIG. 6, the inverting buffer amplifies the current for driving the transducer, inverts the phase, and inputs the amplified current to both drivers. In Fig. 6, the sine wave output is U1B and U1C, and the negative sine wave output is U1D, U1E and U1F.

A transducer driver (TRANSDUCER DRIVER) is constructed as shown in FIG. A waveform of 36 Vpp / MAX is generated by using a double voltage circuit having an inverted 9 Vpp / 40 KHz clock and an 18 V power supply. This signal is emitted through Y1 (TRANSDUCER). The operation state is such that GKDNLGHLFH (Q3) is turned off at the time of operation of the upper circuit (Q1) to output a voltage of 18 Vpp, thereby generating a voltage pulse of maximum 36 Vpp

Next, the inverse coupling circuit will be described.

Since the microphone uses a power line and a signal line together, an inverse coupling circuit is formed as shown in FIG. 8A in order to detect only acoustic signals included in the power source. The current is limited by the resistor R1 and a constant current is supplied, and the high frequency noise included in the power supply is cut off by L1, C1 and C2. The frequency response of the inverse coupling circuit is shown in Figure 8B. FIG. 8A is a configuration diagram of an inverse coupling circuit diagram, and FIG. 8B is a graph showing frequency response characteristics of an inverse coupling circuit.

The preamplifier (Pre Amp) detects a carrier wave of 40 KHz input through an ultrasonic oscillator and converts it into an audible band through a variable frequency oscillator (VFO), and determines whether an arc or a corona occurs. Circuit. 9 is a circuit block diagram of an input section (PREAMPLIFIER TRANSISTOR).

In order to improve the sensitivity of the measured minute signal, an amplifier circuit having a gain of 40 dB is constructed as shown in FIG. The -3 dB frequency band is 280 Hz to 320 kHz, and the 0.1 dB frequency band covers the frequency band of the microphone from 1 kHz to 100 kHz. The frequency response of the amplification circuit is shown in Fig. 10B.

Next, the frequency conversion circuit is constructed as shown in FIG. The 40 kHz band carrier signal input via the transducer receiver is amplified through a preamplifier composed of Q1 and Q2. 11 shows a circuit diagram of the audio band signal amplifying unit and the VFO.

The signal amplified by the input preamplifier is mixed with the signal of V1 of U1 through R11, C3. TP1 is the measurement point of the mixed frequency and determines the VFO frequency by the variable of J5 (50Kohm VR). The signal converted to the audible frequency by the preamplifier output and the output difference of U1 is amplified through the U2 (LM386) audio power amplifier after passing through the band pass filter as shown in FIG. 12, and the ultrasound signal is heard by J5 (SPEAKER or micro headphone) . The configuration of the band-pass filter will be specifically described below.

The carrier signal in the 40 kHz band induced by the transducer drives Q3 through 0.01 uF. The carrier signal through Q3 is input to the comparator (LM386) via the LPF.

The reference level of the comparator is fixed at 2.48V and the comparator output is output when the carrier signal is higher than this level. The + input swing level of the comparator was set to 2.51.

Busbars, transformers, switches, and the like are detected through the ultrasonic sensor 21 as described above.

On the other hand, the ultrasonic sensor 21 is preferably positioned and arranged as shown in FIG. 13 in order to obtain an ultrasonic signal. Preferably, the ultrasonic sensor 21 has a frequency range of 20 kHz to 100 kHz. More preferably, the center frequency used in the ultrasonic sensor 21 is 40 kHz.

The ultrasonic probes are installed between 50 cm and 100 cm in front of the measuring object to obtain a clear response of the ultrasonic signal. Ultrasonic sources are generated by various electrode arrangements. A circuit consisting of a transformer is connected to the discharge source via a coaxial cable. The maximum distance at which ultrasonic acoustic signals are clearly measured is 50 cm, and the corresponding measurement angles are located at 45 °, 0 ° and 135 °. That is, the ultrasonic probe of the ultrasonic sensor 21 is located within 10 cm to 50 cm from the measurement target facility.

Next, the structure of the TEV sensor 22 according to the present invention will be described with reference to Figs. 14 to 22. Fig.

If transient ground voltage for an arc or corona discharge occurs between the object and ground, the ground voltage will change instantaneously and temporarily. Therefore, monitoring of Transient Earth Voltage (TEV) may be effective in detecting and evaluating the discharge and to prevent problems and hazards caused by discharging. Detection of TEV signal accompanying corona discharge is made by using grounded copper plate placed on polystyrene insulator and observing TEV signal on grounded copper plate with detector.

Specifically, the partial discharge generation of electrical equipment and the like in the switchboard generates electromagnetic waves having a spectrum distribution in a wide frequency range from the partial discharge source to all directions. The high frequency component of the radiated electromagnetic wave is more attenuated by the ambient air than the low frequency component. Electromagnetic waves of low frequency components hit the grounded metal clad part of the switchgear, and electromagnetic waves are extracted from the joint part, the air vent, and the gap part. This causes an excessive ground voltage rise in the grounded metal clad portion of the switchgear.

The transient earth voltage has a magnitude in the unit of mV and a rise time of several micro or tens of nanoseconds. It is possible to perform the monitoring diagnosis of the insulation deterioration by detecting the excessive ground voltage generated in the metal enclosure by the partial discharge in the closed switchboard.

The size of TEV is a function of the attenuation of the propagation path between the grounded metal clad and the air medium in the switchgear and the amplitude at the time of partial discharge. The measured value of TEV is calculated in dB as follows.

&Quot; (2) "

dB = 20 log (TEV amplitude / 1 mV)

In the switchgear, the discharge type is represented by surface discharge, internal discharge, and corona discharge. In this discharge, excessive ground voltage is inevitably generated in the metal housing and the enclosure. In particular, measurement of TEV by electromagnetic waves can reduce the size and weight of the sensor.

Discharge within the switchgear housing 10 includes internal discharge, corona discharge, and arc discharge. During the discharge process, the frequency of the electromagnetic wave stimulated by the arc or corona discharge pulse is in the range of tens MHz to several hundred MHz. The TEV can be detected by a sensing sensor, which is generated in the metal housing of the device and installed on the outer surface of the device. Therefore, it is possible to acquire the discharge situation inside the switchboard. The principle of TEV detection can be explained as shown in Fig.

The principle of TEV is illustrated in Fig. 15, which shows an electromagnetic wave caused by an arc or a corona discharge occurring at the junction of the metal wall and the air in the switchgear. It defines the plane between the air zone and the wall of the switchboard.

Assuming air permittivity and permeability respectively ε ₀ and μ ₀ , the electromagnetic wave propagates along the X direction in the air, and its electric field and magnetic field size are as follows.

 &Quot; (3) "

beta is the phase constant of the electromagnetic wave.

 The permittivity and magnetic permeability of the metallic wall of the switchboard are ε and μ, respectively, and the conductivity is σ. If the skin depth of the electromagnetic wave in the conductor is δ and the propagation constant is γ, the propagation coefficient of the electromagnetic wave is as follows.

&Quot; (4) "

The current density currently induced in the conductor can be expressed as:

&Quot; (5) "

Assuming that the electric field parallel to the surface of the conductor is E ₀ , the following equation can be obtained.

 &Quot; (6) "

As shown in FIG. 15, the total current per unit area of the total YOZ flat metal plate is as follows.

&Quot; (7) "

Therefore, the surface impedance per unit area on the metallic wall of the switchgear can be summarized as follows.

&Quot; (8) "

When arc or corona discharge occurs inside the switchboard, high-frequency electromagnetic waves due to the discharge occur on the surface of the metal wall, causing a surface current. The TEV sensor can be mounted on the outer surface of the switchgear so that a pulse voltage (transient earth pressure signal) can be detected. Therefore, the present invention detects the transient earth voltage generated by the surface current of the distribution board due to the corona and arc discharge occurring in the inside of the switchboard.

The time constant and the relationship curve of the TEV signal amplitude and the discharge power can be obtained as shown in FIG. 16 and FIG.

16, when the time constant sigma of the excitation source increases to 50 ns, the TEV signal amplitude sharply decreases from 175.1 mV to 4.9 mV. As the time constant of the source pulse here increases, the pulse width increases. However, the detected TEV signal amplitude decreases. The higher the frequency of the partial discharge source, the more the TEV signal on the surface of the switchboard becomes more dense.

Simulation shows that the TEV signal intensity at the detection points in Figs. 16 and 17 is proportional to the pulse current amplitude of the discharge power source. The higher the pulse amplitude of the excitation source, the stronger the TEV signal on the surface of the switchboard.

When the corona and arc occur in the switchboard, the generated electromagnetic waves are generated by stimulating the TEV signal to the outer surface of the metal enclosure from the open connector and the cover and clearance gap of the switchgear. TEV signal strength and pulse characteristics of corona and arc discharge. The amplitude of the TEV signal is proportional to the amplitude of the discharge pulse. The amplitude of the TEV signal increases as the excitation frequency of the discharge pulse increases. The TEV signal propagates along the surface of the switchboard, creating an apparent time delay. The room power can be detected by positioning according to the arrangement of several TEV sensors.

A TEV detection equivalent circuit using a TEV sensor probe can be represented as shown in Fig. 18, and the operation principle thereof is to detect an electric field formed in the normal direction of the surface of the object to be measured by the generation of arc and corona discharge using a capacitive probe will be. The magnitude of the pulse due to the discharge is proportional to the cross-sectional area of the probe and the incident displacement current density, and the frequency response is determined by the detection impedance Z and the input impedance Z 'of the amplifier circuit.

The TEV sensor 22 according to the present invention comprises a capacitive probe, a coupling network, and a low-noise amplifier circuit as shown in Fig. The planar capacitive probe of FIG. 20 is designed / fabricated in which the detection electrode can be installed parallel to the metal surface.

The TEV sensor 22 probe was made of a copper plate with a thickness of 0.07 mm and an area of 56.5 cm 2 and a flame-retardant epoxy resin having a dielectric constant of 0.2 [mm] and a relative dielectric constant of 4 and an area of 150 [cm 2]. A coaxial cable with excellent high frequency characteristics and a characteristic impedance of 50 [Ω] was used for transmission of the detection signal, and a BNC connector was attached to the ground electrode surface for connection.

(90 to 100 [pF / m]) due to the insulator of the coaxial cable and the external conductor causes distortion of the transmission signal. Therefore, in order to eliminate the influence thereof, a matching resistor which are configured as with R _m and the compensation resistor R _i to Figure 21.

TEV occurs in the form of a high frequency pulse with a rise time of 10 to 20 [ns] at the metal surface of the switchgear. Therefore, a coupling network A _v consisting of the detection impedance and the input impedance of the amplifier circuit is required. A stable device should be used that does not cause burnout or discharge in the voltage range.

The equivalent circuit of Fig. 21 shows the relationship between the output voltage V (t) of the coupling network and the intensity dE (t) / dt of the incident electric field varying with time.

The TEV sensor probe has the capacitance C _e [F], the effective detection area S [m2], the detection impedances R _m [Ω], C _d [F], L _d [H] and the input impedance R _i ] Is A _v , A _v can be obtained as follows.

&Quot; (9) "

In this case, Z _s is the combined impedance of L _d and R _i , which can be obtained as follows.

&Quot; (10) "

Therefore, the output voltage V (t) of the coupling network can be summarized as follows.

&Quot; (11) "

It can be seen that A _v expressed by the synthetic impedance in the above equation acts as a kind of high-pass filter for blocking a commercial frequency component and detecting only a partial discharge pulse of a high frequency component as a coupling network composed of a detection impedance and an input impedance of an amplification circuit , And its generalized frequency response is shown in Fig. 22 (a).

A coupling network _v was enough to detect the TEV voltage pulse in consideration of the components of the TEV voltage pulses occurring in a grounded metallic surface of the switchgear by designing a cut-off frequency that is -3 [dB] to 100 [kHz], The test voltage, 60 [Hz], is attenuated by 130 [dB] or more.

Preferably, the voltage pulse of TEV detected by the TEV sensor probe is very small, so it is fabricated with a low noise amplification circuit.

The frequency response was evaluated by the ratio of the output voltage to the sinusoidal input, which is shown in FIG. 22 (b). The gain ranges from 40 [dB] and -3 [dB] to 500 [Hz] to 45 [MHz].

Next, the configuration of the monitoring apparatus 30 will be described in more detail with reference to FIG.

24, the monitoring apparatus 30 includes a sensor receiving unit 31, a display unit 32, a setting unit 33, an abnormality determination unit 34, and a storage unit 36. Preferably, an alarm unit 35 may be added.

The sensor receiving unit 31 receives the data of the discharge signal measured by the sensor unit 20. [

The setting unit 33 is an input device that sets variables, constants, conditions, and the like for monitoring various monitoring apparatuses such as a reference pattern, an alarm reference, and an alarm type in advance.

Next, the abnormality determination unit 34 determines whether or not an abnormality exists by using the arc or corona discharge signal of each facility 11 of the housing 10, the frequency spectrum of the discharge signal, and the like. A concrete determination method will be described below.

The display unit 32 displays the data of the discharge state or the deteriorated state on the two-dimensional display. That is, the display unit 32 displays the position of the internal equipment of the housing 10 and the measured discharge state in the facility, or displays the deduced discharge state, deterioration state, or deterioration determination result on the screen. Particularly, it is possible to indicate the abnormality of each facility on the layout diagram of the switchboard.

The storage unit 36 stores necessary data such as the positions and positions of the facilities 11 of the housing 10 or the installed ultrasonic sensors 21, the characteristics and patterns extracted from the discharge signals and the discharge signals, and the calculation results of pattern matching . Also, a hysteresis signal pattern for comparing with a pattern of a signal collected in real time is stored.

When the determination unit 34 determines that there is an error, the alarm unit 35 notifies the abnormal state. Particularly, information on the abnormal state and the equipment of the facility or the abnormal state are informed together. When the transient ground voltage (TEV) is detected or the pattern of the real time measurement ultrasonic signal coincides with (similar to) the reference pattern, the alarm is activated. Alternatively, if it is determined that the abnormal state is caused by the discharge state or the deterioration state inference, an alarm corresponding to the abnormal state is generated.

The information collected through the TEV sensor or the ultrasonic sensor is stored in the database and the alarm is activated if the real-time measurement ultrasonic wave matches or is similar to the pattern of the boundary. At this time, sudden arc or corona discharge may be changed due to failure of the TEV sensor, ultrasonic sensor, peripheral equipment, or surrounding fire, so that quick action is required. Therefore, when an alarm occurs, the location of the alarm should be automatically displayed on the screen and the problem can be found.

Next, a rough configuration of the abnormality determination unit 34 according to an embodiment of the present invention will be described in detail with reference to FIG. 25 is a configuration diagram of the abnormality determination unit 34 according to the present invention.

25, the abnormality determination unit 34 determines whether or not an abnormality exists in the inside of the housing 10 based on the environmental information such as the internal ultrasonic signal of the switchboard detected from the sensor unit 20, the ultrasonic signal of each facility, A noise removing unit 132, a discharge detecting unit 133, and a control unit 135 so as to extract and diagnose the discharge state or deterioration state information of the discharge state or the deteriorated state of the battery.

The method of hearing and determining the sound measured by the ultrasonic sensor 21 depends on the subjective response of the individual, and it is very difficult to hear and discriminate the sound. It should also be noted that the generation of ultrasonic waves may be caused by an abnormality of the mechanical equipment (bearing, piping leakage, etc.). Nevertheless, when the ultrasonic sensor 21 is used to measure the sound, the corona is constantly buzzing because it discriminates the sound, and the arc generates abnormal explosive sound or plosive sound with sudden start and stop of energy.

Preferably, when ultrasonic waves are measured at 1,000 V or less and a buzzing sound is heard, it can be discriminated as an arc. This is because corona is unlikely to occur at 1,000 V or less.

Ultrasonic diagnosis is a diagnostic method using ultrasound signal characteristics by discharging. It receives ultrasound center frequency of 40 kHz generated by discharge by a ceramic phone, converts it into an electric signal, amplifies and detects it, and detects the source by displaying the level.

The detected ultrasonic noise can be heard by a speaker at the same time and receives 30kHz ~ 60kHz which is higher than the audible frequency in order to secure the detection distance of the ultrasonic wave generated at the discharge spot. The reason for choosing the reception frequency band from 30 kHz to 60 kHz is that it is difficult to distinguish it from the ambient noise at low frequencies and at the higher frequencies, the overall loss in the atmosphere increases.

The arc or corona discharge occurs when the surrounding air molecules are electrically discharged or ionized, and the chemical reaction that occurs when the electrical force ionizes the air molecules around the insulator causes corrosion of the metal part and failure of the insulation compound. The high energy at the corona discharge site can damage the mechanical components and cause failures.

Tracking during the discharge of ultrasonic waves is mainly caused by the electric current flowing through the contamination source on the surface of the insulator, and the current flowing at this time is not an energy source and no heat is generated. Therefore, it is very difficult to detect it except ultrasonic diagnosis.

Contamination is mainly caused by dust, moisture, etc., and flashing phenomenon occurs when a low sound with a sizzling sound is sustained. This flashover seems to be quiet, but gradually develops into an arc current and eventually develops into a destructive arc.

Corona discharges treated by ultrasonic waves are typical, and the phenomenon occurring between the grounded part of the electric field and the potential difference shows a very short cycle pattern. 26 shows a typical frequency spectrum distribution of a corona discharge.

It is a final phenomenon developed from the previous tracking. It is characterized in that the amplitude is extremely large and the discharge cycle is not constant. If an arc is generated, it is necessary to stop the apparatus in operation. 27 shows a representative frequency spectrum distribution of the arc discharge.

Fig. 28 shows an example of the ultrasonic signal and the current pulse waveform measured when the corona discharge is generated. Ultrasonic components of 20 kHz ~ 100 kHz band were present in the corona discharge, and especially, components of 30 kHz ~ 50 kHz were 8 mV ~ 10 mV.

FIG. 28 is a graph of the corona discharge frequency band. FIG. 28 (a) shows an ultrasonic signal [100 mV / div, 10 ms / kHz / div].

Fig. 29 shows the measured ultrasound signals and the frequency spectrum distribution at the time of series arc discharge in the carbon-copper electrode, the wire-wire and the terminal block. As a result of frequency spectrum analysis of ultrasound signals, 30 kHz ~ 50 kHz components were present in the carbon - copper electrode as well as corona discharge, and 30 kHz ~ 60 kHz components were large in the wire - conductor and terminal block.

FIG. 29 is a graph of a carbon-copper electrode arc discharge frequency band. FIG. 29 (a) shows an ultrasonic signal [100 mV / div, 10 ms / / div, 10 kHz / div].

First, the signal conversion unit 131 will be described.

The signal converting unit 131 converts the signal of the discharge source, that is, the received ultrasonic signal or the transient ground voltage (TEV) into a signal waveform. The ultrasonic signal is a signal measured by the ultrasonic sensor 21 located at 50 cm from the discharge source and the transient ground voltage TEV is a voltage pulse signal of TEV measured at the probe of the TEV sensor 22. [ The ultrasonic signal data or the voltage pulse data of TEV is converted into a signal waveform.

Next, the noise removing unit 132 applies a FIR filter (Finite Impulse Response filter) to the converted signal waveform to remove circuit noise and other impulses included in the ultrasonic signal. At this time, the background noise is analyzed for the cutoff frequency for the FIR filter, and the frequency is set based on the background noise. At this time, the ultrasound signal when the transient ground voltage of TEV sensor is below the reference value is analyzed as background noise.

The performance of ultrasound identification is related to the number of ultrasound signals needed to find the correct key. Therefore, in order to obtain high identification performance, it is necessary to acquire a pure ultrasound signal from which unwanted distortion is removed. However, distortion factors such as noise are inevitably included in the measured ultrasound signal.

The FIR filter is composed of left and right adjacent data centered on the data to be filtered, and performs a filtering operation with a product of a window composed of predefined weights (for example, coefficients) and the sum of the products.

In this case, the input data is repeatedly moved and operated on the window composed of weights. When the data to be filtered is weighted to the center of the filter, the filtered data is obtained as a result of applying the weight to the target data and the adjacent data. have.

The moving average filter provided with the circuit noise and the impulse removed ultrasonic signal from the FIR filter linearizes the moving average value having a stable and appropriate response speed by varying the number of buffers according to the variation of the measured values of the ultrasonic waves. Where the moving average filter is a filter that takes an average over a constant sample interval for all samples in the guard interval, among the sinusoidal samples obtained by the FIR filter. The moving average filter has the same structure as the FIR filter because it is composed of N-1 delay taps. The content of each delay tap is multiplied by the corresponding weight and output as a single value through the adder (?). If all the weights are set to 1 / N _T , the averaging effect reduces ICI and noise components, and at the output of the filter, a sample component with improved signal-to-noise ratio appears. The number of delay taps N _T has a high correlation with the complexity and performance of the filter. The larger the N _T , the higher the complexity, the smaller the ICI and the noise reduction due to the averaging, while the smaller the N _T , the smaller the complexity and the smaller the noise reduction. Therefore, it is necessary to select an appropriate N _T value in consideration of complexity and performance.

In addition, since the FIR filter performs filtering with only certain values of the input signal, when the same characteristic is implemented, the FIR filter has a disadvantage in that it has a higher degree of computation compared to an IIR (Infinite Impulse Response) filter, but is stable at all times.

In order to design the HF-FIR filter, the LF-FIR filter must be designed first.

When the arc or corona discharge is simulated, it can be seen that the ultrasound signals from these discharges mainly detect signals in the 30 kHz to 60 kHz band. Therefore, a band-pass filter having the same frequency response as shown in FIG. 23 can be constructed. The -3 dB frequency band is 30 kHz to 60 kHz and the -0.1 dB frequency band is 38 kHz to 48 kHz.

Since there is a high possibility that a lot of noise is mixed in the low frequency band, the ultrasonic signal in the low frequency band is excessively blocked. However, in order to more accurately analyze the arc or corona discharge, it is advantageous to analyze an ultrasonic signal including a low frequency band. Therefore, the lower the cut-off frequency of low frequency is, the easier it is to analyze the accurate ultrasonic signal.

Therefore, frequency analysis is performed on the background noise in a state in which no discharge occurs, and a frequency having a predetermined magnitude (or decibel) or more is set as the cutoff frequency. For this purpose, when the transient ground voltage (TEV) measured by the TEV sensor 22 is equal to or smaller than a predetermined size, an ultrasonic signal is detected from the ultrasonic sensor 21. At this time, the frequency of the detected ultrasonic signal is analyzed, and a frequency of a predetermined size (or decibel) or more is sought. And sets the detected frequency to the cutoff frequency.

It is assumed that the frequency range of the discharge due to simulation in the absence of noise is set to 30 kHz to 60 kHz, which is determined to be appropriate, and a predetermined frequency range (referred to as a standard frequency range). By analyzing ultrasonic signals below 30kHz, the ultrasonic signals can be analyzed more accurately. For example, if the background noise is not substantially in the range of 10 kHz to 30 kHz, a more accurate analysis is possible if the bandwidth of the ultrasonic signal is broadened to 10 kHz to 60 kHz.

In addition, if there is a lot of background noise between 30 kHz and 40 kHz, this frequency band can be excluded and the ultrasound signal for the remaining 40 kHz to 60 kHz can be analyzed.

That is, when the transient ground voltage TEV measured by the TEV sensor 22 is lower than the predetermined reference voltage, the ultrasonic sensor 21 detects the ultrasonic signal. At this time, the predetermined reference voltage is a predetermined value and defines the voltage magnitude when the discharge state does not occur. The reference voltage is obtained in advance through simulation.

At this time, a frequency having a size larger than the minimum noise size is extracted with respect to the detected ultrasonic signal. The extracted frequency is set as the cutoff frequency.

Preferably, the cutoff frequency range is set in advance, and the cutoff frequency is extracted within the frequency range. For example, if the cutoff frequency range is set to 10 kHz to 40 kHz, and if the cutoff frequency is not found, the cutoff frequency is set to 10 kHz, which is the minimum value of the cutoff frequency range.

The cut-off frequency f _c obtained as described above is set.

The digital frequency (Ω ₁ ) is calculated as follows.

&Quot; (13) "

Where f _s is the sampling frequency.

The LF-FIR filter coefficient h ₁ [n] is obtained using the following equation.

&Quot; (14) "

Select window w [n] to determine the order of the LF-FIR filter (N, limited by an odd number) and reduce frequency spectrum leakage. The following equation (15) represents a Hamming window function used in the FIR filter designing process.

&Quot; (15) "

As a result, the impulse response h [n] of the LF-FIR filter is expressed by the following equation.

&Quot; (16) "

The relationship between the HF-FIR filter impulse response (h _high [n]) and the LF-FIR filter impulse response (h _low [n]) is determined by the following equation to eliminate signal noise.

&Quot; (17) "

Therefore, noise reduction of the ultrasonic signal, implements a _high h [n] using the following equation input signal x [n] and the convolution (convolution) operation.

&Quot; (18) "

On the other hand, the impulse response must be calculated in real time with the ultrasonic signal. However, in order to analyze the ultrasonic signal on the screen, the ultrasonic wave length (or the number of ultrasonic waves) and the number of data of the order N must exist in order to analyze the ultrasonic signal on the screen because the data can not be used by the degree N in the characteristics of the FIR filter operation. Therefore, the amount of ultrasound signal computation for outputting to the screen every time becomes the number of ultrasonic waves × N.

To this end, the present invention uses a data movement method to reduce the amount of data operation. That is, after obtaining the N pieces of the ultrasonic data [X ₁ , X ₂ , ..., X _N ] in the work thread, the LF-FIR filter operation is applied to only the newly received ultrasonic data X _new and the ultrasonic signal is analyzed. The stored data is moved and stored one by one for the next calculation, and a storage space for newly received ultrasonic signal data is prepared. 30 shows a proposed data movement method for applying FIR filtering to ultrasound signal data in real time.

In FIG. 30, only the X _new data is additionally included and interpreted as the ultrasonic signal data to be subjected to the FIR filtering. Therefore, the FIR filtering operation amount is reduced from the original number of ultrasonic waves × N to the operation amount of N.

Therefore, when FIR filtering is performed as in the calculation method shown in FIG. 30, except for the process of acquiring data for the first 5 minutes, data reception and necessary processes are performed in real time, and required digital signal processing processes are performed.

The following method was applied to detect the discharge peak position of the ultrasonic signal. First, the differential value d (n) of the ultrasonic signal is obtained as shown in Equation (19).

&Quot; (19) "

Where e (n) is the ultrasound signal. After expressing the value of d (n) as a positive number, the value of the peak value of discharge is emphasized by using a moving average filter as shown in Equation (20). Here, the length of the filter is 5.

(20)

As a result, the data maximum value is interpreted as a peak due to discharge within a certain range based on the value of the expression (20). Preferably, if the n-th ultrasonic signal is larger than the predetermined peak ratio in comparison with the size of the moving average filter F (n), the n-th ultrasonic signal is determined as a peak. For example, if the peak ratio is set to 20%, if it is 20% larger than the size of the moving average filter, it is determined as a peak. Preferably, the peak ratio is set at 10% to 50%.

Also, in order to find the interval between discharge peaks, the peak time values detected by the method shown in Equation (20) should be composed of R _N. (21) is data consisting of N R ₁ , R ₂ , ..., R _N.

&Quot; (21) "

That is, to obtain the peak interval value of the discharge, it is possible to obtain the difference of the nth time from the (n + 1) th time. The obtained peak interval value is used as basic data for identifying the discharge.

Preferably, the characteristic values using the peak of the discharge are the size of the peak (or the average size of the peak), the number of peaks (or the number of peaks per unit time), the interval of peaks (or the average interval of peaks), and the like. The characteristic values are characteristic values for classifying the discharge. These characteristic values are used to classify the types of discharges.

The detected data of the previously obtained peak interval is non-equilibrium data. Basically, to calculate the spectrum of an ultrasonic signal, cubic spline interpolation is used to convert boiling interval data into equidistant data. Preferably, the cubic spline interpolation method is expressed by a curve connecting two points by a third degree polynomial.

If the data of the peak interval after the third spline interpolation process is changed to the frequency domain, the DC component is expressed too large compared to other frequencies, so that the spectrum information of the other frequency domain is distorted. Accordingly, the LF-FIR filter parameters are designed.

Then, the impulse response of the HF-FIR filter is obtained by applying equations (15) to (17).

FFT is used to estimate the frequency domain of the ultrasonic signal due to discharge. FFT is an algorithm that can reduce the number of calculation operations of Fourier transform. In order to calculate FFT, the number of data must be a multiplier of 2. As described above, the data of the discharge peak interval is subjected to the cubic spline interpolation method and the FIR filter process, and then the FFT is calculated. The zero-padding scheme is used to fill a zero value because the number of FIR-filtered data is not represented by a multiplier of 2.

Next, the discharge detector 133 detects whether an arc or a corona discharge is generated and the type of a discharge using the ultrasonic signal from which the noise has been removed. Since the noise was removed by FIR filtering, the noise-canceled ultrasonic signal is actually a signal due to arc or corona discharge.

Preferably, the discharge detector 133 determines that a discharge is generated when the transient ground voltage is measured by the TEV sensor 22 to be equal to or higher than a predetermined minimum reference value, and at this time, Or the ultrasonic signal of the corona discharge.

Also, preferably, the discharge detector 133 previously stores and holds feature value data for each type of discharge, and compares the feature values extracted from the ultrasound signals with the stored feature value data to search for the most similar one. The kind of the detected discharge is judged as the detected kind. The characteristic value of the ultrasonic signal is obtained by the peak of the ultrasonic signal as described above. That is, the characteristic value is the size of the peak (or the average size of the peak), the number of peaks (or the number of peaks per unit time), the interval of peaks (or the average interval of peaks), and the like.

An ultrasonic signal from which noise has been removed can be detected by an arc or a corona discharge according to a time series. Figs. 31, 28, and 29 show the waveforms of the analyzed ultrasonic signals. Fig. 31 shows a normal waveform, that is, a normal waveform in which no arc or corona discharge is generated, and Figs. 28 (a) and 19 (a) show waveforms at arc and corona discharge, respectively.

First, in the case of the normal waveform in Fig. 31, a certain type of waveform is detected over time, and there is almost no change in amplitude. In the case of the waveform of the arc discharge shown in Fig. 28 (a), it can be seen that the amplitude of the waveform becomes larger each time an arc is generated as compared with the normal waveform of Fig. It can be seen that the corona discharge of FIG. 29 (a) continuously exhibits a waveform of a large amplitude.

Therefore, if the waveform of the amplitude of the ultrasound signal from which the noise has been removed continues to increase beyond a predetermined size, the discharge detector 133 determines that an arc or a corona discharge has occurred.

Also, the discharge detector 133 compares the size of the peak extracted from the ultrasonic signal, the number of peaks, and the peak interval with a predetermined pattern to determine the type of arc or corona discharge. That is, the characteristic values for determining the type of discharge are the size of the peak of the ultrasonic signal, the number of peaks, and the peak interval.

Next, the control unit 135 causes the display unit 140 to display the detected result of the arc or the corona discharge by the ultrasonic wave classification from the discharge detection unit 133, 50 to notify the discharge or deterioration state of the switchboard.

Or the display unit 140, or outputs an ultrasonic signal through a speaker or the like. The manager can listen to the ultrasonic signal to determine the type of arc discharge or corona discharge, or determine the degree of defect.

Further, the control unit 134 transmits the discharge information in the housing 10 diagnosed by the remote server 50 so as to control the degree of discharge of the power-saving half-live portion based on the calculated discharge information.

Although the present invention has been described in detail with reference to the above embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention.

10: Switchgear housing 11: Power equipment
20: sensor part 21: ultrasonic sensor
30: Monitoring device 31: Sensor receiving part
32: display section 33: setting section
34: abnormality determination unit 35: alarm unit
36: Storage unit 40: Remote server
131: Signal conversion unit 132: Noise removal unit
133: discharge detector 135:

Claims (9)

A state monitoring and diagnosing system based on an ultrasonic wave and an excessive ground voltage for diagnosing a state of discharge or partial discharge of an arc or a corona of a housing including a power control panel of any one of a high pressure chamber, a low pressure chamber, a distribution panel and a motor control panel In a power control panel of any one of a high-pressure chamber, a low-pressure chamber, a distribution chamber, and a motor control chamber,
A plurality of ultrasonic sensors for detecting ultrasonic waves generated by an arc or a corona discharge in contact with or proximate to a power facility provided in the housing, and a plurality of ultrasonic sensors provided outside the housing or the electric power facility, A TEV sensor configured to detect a transient earth voltage (TEV) generated; And
A controller for detecting an arc or a corona discharge occurring outside the electric power facility using the ultrasonic signal detected by the sensor unit and detecting an arc or a corona discharge generated outside the electric power facility by using the transient ground voltage detected by the sensor unit, And an abnormality determining unit configured to detect a partial discharge occurring in the electric power facility and to control an internal state of the housing in accordance with the detected arc or corona discharge and partial discharge information,
The abnormal presence /
A TEV sensor detects an ultrasound signal of background noise through the ultrasonic sensor when the transient ground voltage is measured to be less than a predetermined minimum reference value by the TEV sensor and outputs a signal having a frequency larger than a predetermined minimum noise size And designing a finite impulse response (FIR) filter by setting a cutoff frequency at a detected frequency. When the transient ground voltage is measured by the TEV sensor to be equal to or higher than a predetermined minimum reference value, The ultrasonic signal of the arc or corona discharge is detected and the noise of the ultrasonic signal is removed through the FIR filter designed for the ultrasonic signal of the detected arc or corona discharge,
Detects the arc or corona discharge from the detected excessive ground voltage and the ultrasonic signal from which the noise is removed, determines the type of discharge,
Wherein the abnormality detection unit extracts a peak of a discharge from the ultrasonic signal and determines at least two or more of the average size of the peak, the number of peaks per unit time of the peak and the average interval of the peak as a characteristic value, Classify the type of discharge,
The abnormality determination unit obtains the moving average filter F (n) for the n-times ultrasonic signal e (n) according to the following equation 1 and calculates the moving average filter F (n) (N) is determined as a peak when the peak value of the ultrasonic signal is larger than a predetermined peak ratio in comparison with the size of the ultrasonic signal and the amplitude of the ultrasound signal. A power control panel of any one of a distribution board, a motor control board.
[Equation 1]

Here, e (n) is an ultrasonic signal of n time, and L is a predetermined value as a length of a filter section of the moving average filter.
The method according to claim 1,
Wherein the ultrasonic wave generated from the ultrasonic wave sensor is measured in the frequency range of 30 kHz to 48 kHz from the ultrasonic sensor, and the ultrasonic wave is measured from the ultrasonic wave sensor in the range of 30 kHz to 48 kHz.
delete The method according to claim 1,
Wherein the abnormality determination unit sets the range of the cut-off frequency in advance, extracts the cut-off frequency within the frequency range, and sets a frequency larger than a predetermined minimum noise size in the range of the cut-off frequency in the ultrasonic signal of the background noise And the control unit extracts the lowest frequency in the range of the cut-off frequency as the cut-off frequency when it is impossible to detect the cut-off frequency of the high voltage, low voltage, distribution board and motor control board mounted on the ultrasonic and transient ground voltage based condition monitoring diagnostic system Any one power control board.
delete delete The method according to claim 1,
The abnormality detection unit uses an LF-FIR (Low Frequency FIR) filter and an HF-FIR (High Frequency FIR) filter to remove noise from the ultrasonic signal, and the HF-FIR filter removes noise from the LF- 2], and then,
Wherein the filter coefficient h ₁ [n] of the LF-FIR filter is obtained by the following equation [3]: [Equation 3] Lt; / RTI >
[Equation 2]

Where h _high [n] is the impulse response of the HF-FIR filter, h _low [n] is the impulse response of the LF-FIR filter, and n is an integer.
[Equation 3]

Where f _c is the cutoff frequency, and f _s is the sampling frequency.
The method according to claim 1,
The ultrasonic sensor includes:
A frequency converter including a frequency mixing circuit and a local oscillation circuit for dropping the ultrasonic signal to an intermediate frequency;
An amplifying unit for amplifying the intermediate frequency; And
And a demodulator for separating the original signal of the audible frequency from the amplified signal,
The ultrasonic sensor uses a power supply line and a signal line together and forms an inverse coupling circuit to detect only an acoustic signal included in the power supply,
Wherein the inverse coupling circuit comprises first and second capacitors connected in parallel between the power supply and the ground and a first conductor connected in series between the first and second capacitors to generate a high frequency noise included in the power supply Voltage control panel, a power distribution board, and a motor control panel mounted with an ultrasound and transient ground voltage based condition monitoring diagnostic system.
The method according to claim 1,
The TEV sensor ultrasonic comprises a coupling network which consists of resistance R _m, capacitance C _d, the detection impedance inductance L _d are connected in series, an input impedance R _i of the inductance L _d and the amplifiers coupled in parallel, And a power control board of any one of a high-pressure panel, a low-pressure panel, a distribution panel, and a motor control panel equipped with a transient ground voltage based condition monitoring diagnosis system.

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