AU2003229345B2 - Residual current circuit breaker - Google Patents
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- AU2003229345B2 AU2003229345B2 AU2003229345A AU2003229345A AU2003229345B2 AU 2003229345 B2 AU2003229345 B2 AU 2003229345B2 AU 2003229345 A AU2003229345 A AU 2003229345A AU 2003229345 A AU2003229345 A AU 2003229345A AU 2003229345 B2 AU2003229345 B2 AU 2003229345B2
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
- H02H3/33—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors using summation current transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0092—Details of emergency protective circuit arrangements concerning the data processing means, e.g. expert systems, neural networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/04—Arrangements for preventing response to transient abnormal conditions, e.g. to lightning or to short duration over voltage or oscillations; Damping the influence of DC component by short circuits in AC networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/006—Calibration or setting of parameters
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Emergency Protection Circuit Devices (AREA)
- Measurement Of Current Or Voltage (AREA)
- Keying Circuit Devices (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Breakers (AREA)
Description
WO 03/100938 PCT/AT03/00147 Residual current circuit breaker The present invention relates to a residual current circuit breaker having a unit for detecting a fault current within an electrical power supply network and a network disconnection unit, the unit for detecting a fault current comprising a device for correctly recording the signal of the fault current which may be coupled to the power supply network, and the unit for detecting a fault current comprising a fault current analysis unit for spectral characterization of the fault current which is connected to the network disconnection unit.
Due to the increasing use of converters, switched-mode power supplies, power electronics units, or the like in power supply networks, non-sinusoidal fault currents are to be expected to an increased extent. While purely sinusoidal signals do not cause false tripping in typical residual current detection systems, such as residual current operated devices, the signals subject to higherorder harmonics and non-harmonic superpositions of signals lead to undesired effects in the analog electronics currently used for fault current detection, such as rectification, demodulation, resonance and filter behavior, etc., which, beyond a specific complexity of the electronic circuit system provided for the fault detection, negatively influences the tripping behavior and therefore may lead to impairment of safety. Demodulation effects, coupling capacitances, and resonance effects or the like are thus the causes of unpredictable tripping behavior of conventional residual current circuit breakers.
0 WO 01 95451 A deals with a software-supported fault current determination for security and monitoring systems. In this case, the signal of the fault current is c imaged correctly and the frequency of an occurring fault current is determined 0 using a software routine and the fault current is classified and evaluated. The fault current is classified in one of three frequency classes and possibly divided further in regard to the type of the fault current, alternating fault current, pulsating fault current, direct current. Depending on the classification of the fault current, other stored triggering limit values are used for the level of the fault current. An embodiment according to WO 01 95451 A has the disadvantage that it is only described for one single fault current having a specific frequency. Using a method according to WO 01 95451 A, a complex fault current signal which is composed of various components having different frequencies cannot have its signal evaluated correctly.
The object of the present invention is therefore to specify a residual current circuit breaker which displays predictable tripping behavior even in the event of fault currents which are not purely sinusoidal.
It is a further object of the present invention to allow the detection of fault currents over a wide frequency range.
Furthermore, it is the object of the present invention to be able to call a running judgment of the fault currents arising in a network.
SUMMARY OF THE INVENTION In one aspect, the present invention provides a residual current circuit breaker having a unit for detecting a fault current within an electrical power supply network and a network disconnection unit, the unit for detecting a fault current including a device for correctly recording the signal of the fault current, which may be coupled to the power supply network, and the unit for detecting a fault current including a fault current analysis unit for spectral characterization of the fault current, which is connected to the network disconnection unit, characterized in that the fault current analysis unit includes at least one filter unit having a preferably low-frequency bandpass characteristic for filtering the fault current signal, and a transformation unit, for transforming the fault current signal produced in the device for correctly recording the signal of the fault current from the time range into an image range, preferably into the frequency range.
O In this way, the fault current is no longer judged according to its effective Svalue, but rather observed as a signal whose frequency components are fed to a c signal analysis with the aid of mathematical methods. On the basis of the results 0 thus achieved, precise monitoring of the permissible maximum value may be performed and predictable tripping of the residual current circuit breaker may thus be implemented. Through the filter unit, above all the component of the lowfrequency oscillations in the fault current may be taken into consideration in the measured value calculation.
This way of observing the fault current is made possible at a reasonable cost through digital signal processing. In a further embodiment of the present invention, the unit for detecting a fault current may also comprise a unit for scanning and quantifying the fault current, preferably an analog/digital converter.
The point of the signal processing path at which a conversion from analog signal into digital signal occurs may be different depending on the design of the signal processor, digital signal processors being especially suitable for implementing this.
In order to avoid corruption of the signal scanned in the analog/digital converter, according to a further embodiment of the present invention, the unit for detecting a fault current may further comprise an anti-aliasing filter.
In a further embodiment of the present invention, the device for correctly recording the signal of the fault current may be formed by a Forster probe, whose output is connected to a regulator unit which compensates the output signal applied at the output of the F6rster probe to zero.
The output signal of the F6rster probe is used in this case as the regulated variable for the regulator unit, whose object is to compensate the output signal to zero. In this way, the signal of the fault current is imaged correctly.
In order to reciprocally bring the magnetic material of the F6rster probe into saturation, in a further implementation of the present invention, a modulator may be provided for pre-magnetization of the F6rster probe. A fault current signal may then be recognized in that it leads to a different saturation of the magnetic material than that predefined by the pre-magnetization.
Other types of probes which are capable of correctly representing the signal of a fault current may also be used as the probe. Without restricting generality, in a refinement of the present invention, the device for correctly recording the signal of the fault current may be formed by shunts, Hall-effect devices, or combinations of magnetic and Hall-effect devices.
According to a further implementation of the present invention, the at least one filter unit may be formed by a filter unit having low-pass characteristic, whose output is connected to a signal evaluation unit, preferably a unit for calculating the effective value of the filtered fault current signal, the transformation unit is connected to a spectral evaluation unit, preferably a unit for calculating the effective value of the frequency spectrum, and the output of the signal evaluation unit and the output of the spectral evaluation unit are connected to inputs of a summation unit and the output of the summation unit is connected to a maximum value monitoring device which is
I
connected to the network disconnection unit, this maximum value monitoring device actuating the network disconnection unit if a predefinable limiting value is exceeded.
Fourier transformation, particularly in the form of fast Fourier transformation, represents a transformation method which is already applicable in many ways with the support of integrated circuits. In a further embodiment of the present invention, the transformation unit may be formed by a Fourier transformation unit, particularly a discrete Fourier transformation unit.
However, other mathematical transformation methods may also be expediently applied in the framework of the present invention. In a preferred variation of the present invention, the transformation unit may be formed by a Gabor transformation unit or a wavelet transformation unit, which allows statements about the time behavior of the frequency spectrum of the fault current signal.
In a further embodiment of the present invention, a correlation unit, which is connected to a unit for storing at least one comparative spectrum, is connected between the output of the transformation unit and input of the spectral evaluation unit.
Through the comparison with a comparative spectrum which characterizes the normal state, the threshold for exceeding a maximum value may be related to a specific frequency range.
In a further embodiment of the present invention, the output of the transformation unit may be switched to the input of a signal configuration unit which is connected to a memory input of the unit for storing at least one comparative spectrum and to an input of the at least one filter unit for setting filter coefficients.
O The signal necessary for the comparison in the correlation unit is C processed and analyzed in the signal configuration unit. Furthermore, it allows the c filter coefficients of the filter unit to be influenced.
0 In another variation of the present invention, the at least one filter unit is formed by two or more filter units having a bandpass characteristic connected in parallel, which have inputs for setting filter coefficients and whose outputs are each connected via a signal evaluation unit to inputs of a summation unit and the output of the summation unit is connected to a maximum value monitoring unit Nwhich is connected to the network disconnection unit, this maximum value monitoring unit actuating the network disconnection unit if a predefinable limiting value is exceeded, and the transformation unit is connected to a signal configuration unit whose outputs are connectable to the inputs for setting filter coefficients.
With the aid of the two or more filter units having bandpass characteristic, the total frequency range of interest for the fault current signal is covered. The filter coefficients are determined with the aid of the transformation unit. After setting the coefficients, the fault current is monitored with the aid of the filter units in the time range.
In another aspect, the present invention provides a method for fault current monitoring of a power supply network, in which a network disconnection unit is activated as soon as it is determined a fault current measured value derived from a fault current measurement has exceeded a maximum value, characterized in that the correct signal of the fault current is transformed from the time range into the image range, preferably into the frequency range and, from the resulting spectrum, either a partial amount of the fault current measured value is calculated and/or the setting of the filter coefficients of at least one filter having bandpass characteristic for preferably low-frequency filtering of the correct signal of the fault current is determined, the fault current measured value or a partial amount thereof being calculated from the output signal of the at least one low-pass filter.
The objects of the present invention cited at the beginning are achieved according to the present invention in that the signal of the fault current is imaged correctly, the correct fault current signal is transformed from the time range into the image range, preferably into the frequency range and, from the resulting spectrum, either a partial amount of the fault current measured value is calculated and/or the setting of the filter coefficients of at least one low-pass filter for filtering the correct signal of the fault current is determined, the fault current measured value or a partial amount thereof being calculated from the output signal of the at least one filter having bandpass characteristic.
In a refinement of the method according to the present invention, the spectrum of the fault current signal may be compared to at least one stored frequency spectrum. The fault current signal may thus be compared to the spectral fault current components typically arising in the system to be protected and newly arising spectral fault current components may be recognized.
In this context, the fault current measured value may be produced from the partial amount of the fault current measured value calculated from the spectrum and the partial amount of the fault current measured value calculated from the at least one filter having bandpass characteristic.
All partial amounts determined are thus evaluated.
Through the evaluation of the fault current as a signal having a frequency spectrum, false tripping of the residual current circuit breaker is avoided.
In the following, the present invention will be explained in greater detail on the basis of the exemplary embodiments illustrated in the drawing.
Figure 1 shows a block diagram of an embodiment of the residual current circuit breaker according to the present invention; Figure 2 shows a simplified block diagram of the residual current circuit breaker shown in Figure 1; Figure 3 shows a simplified block diagram of a further variation of the present invention; Figure 4 shows a schematic illustration of the configuration operation of the residual current circuit breaker shown in Figure 1; Figure 5 shows a schematic illustration of the normal operation of the residual current circuit breaker shown in Figure 1, and Figure 6 shows a part of a block diagram of a further embodiment of the residual current circuit breaker according to the present invention.
Figure 1 schematically shows a general electrical power supply network 40, whose access for a consumer (not shown) may be interrupted by a network disconnection unit 20. As soon as a fault current, which exceeds a predefinable fault current measured value, begins to flow in the power supply network 40, the network disconnection unit 20 is actuated and danger to people is thus prevented. The occurrence of such a fault current is monitored by a unit for detecting a fault current 42.
According to the present invention, the unit for detecting a fault current 42 comprises a device for correctly recording the signal of the fault current 1, 41, which may be coupled to the power supply network 40 and may be implemented in different ways in the framework of the present invention.
9 O In the exemplary embodiment according to Figure 1, the device for correctly recording the signal of the fault current is formed by a Forster probe 41, c whose output is connected to a regulating unit 1, which compensates the output signal applied to the output of the Forster probe 41 to zero. The regulator unit 1 comprises a PID regulator 43, whose regulated variable is formed by the output signal of the Forster probe 41. Through the compensation of the output signal of the Forster probe 41, a correct image of the signal of the fault current is generated at the output of the PID regulator 43.
However, other devices may also be used as the device for correctly recording the signal of the fault current, such as shunts, Hall-effect devices, or combinations of magnetic and Hall-effect devices. The types of regulators used in this case are also not subjected to any restrictions, like the Forster probe 41 in the above-mentioned case. The correct image of the signal of the fault current implemented in this way allows the detection of fault currents within a very broad frequency range, from 0 Hz, direct current, to approximately 20 kHz.
A modulator 44 is provided for pre-magnetization of the Forster probe 41, whose object is to bring the magnetic material of the Forster probe 41 reciprocally into saturation. This may be performed by a suitable signal generator which is connected to a coil of the Forster probe 41. A spectrum arises which contains only odd higher-order harmonics, since it is derived from a rectangular signal, for example. A fault current signal thus leads to a different saturation of the magnetic material, which would then lead to the occurrence of even higher-order harmonics.
In the Forster probe 41, the second harmonic (even higher-order harmonic) is used to judge the fault signal, for example. In this case, the second higher-order harmonic is compensated to zero with the aid of the PID regulator 43, in order to thus obtain a correct image of the fault current signal.
A correction unit 45 connected to the PID regulator 43 is connected to a temperature measurement probe 46 positioned in the region of the Forster probe 41 and measures its temperature. In this way, a compensation of the temperature response of the Forster probe 41 may be performed.
For judging the fault current signal, according to the present invention, the unit for detecting a fault current 42 also contains a fault current analysis unit 100 for spectral characterization of the fault current, which is connected to the network c disconnection unit o In order to avoid the difficulties which arise in the previously known residual current circuit breakers, the fault current is not determined solely by simply exceeding a threshold value, but rather is treated as a signal which is a function of time, taking the different frequency components which compose this signal into consideration.
After mathematical analysis of the fault current signal has been performed, N a suitable reaction may be performed as a result of the analysis.
SIn principle, the further processing of the fault current signal derived from the unit for detecting a fault current 42 may be either analog or digital. In practice, the initially analog fault current signal is preferably converted into a digital fault current signal in order to keep the complexity for evaluating the fault current signal as low as possible, through which miniaturization of the residual current circuit breaker according to the present invention is possible.
The correct fault current signal obtained from the PID regulator 43 is fed in Figure 1 to an amplifier 2, connected to the output of the PID regulator 43, having a variable application factor, which may be influenced via the correction unit 45, for example, in order to allow temperature compensation of the F6rster probe 41 via the amplification factor.
A unit for scanning and quantifying the fault current is connected to the output of the amplifier 2 in the form of an analog/digital converter 3, which converts the analog fault current signal into digital information. This conversion may also be performed at a different point of the signal path depending on the construction of the residual current circuit breaker according to the present invention.
To avoid scanning errors, an anti-aliasing filter known from the related art is also provided in the analog/digital converter 3.
The amplifier 2 may be provided as an analog signal application unit at the location shown in Figure 1, but it may also be implemented using software by multiplying the fault current signal digitized in the analog/digital converter 3 with coefficients, the temperature response of the F6rster probe 41 being taken into consideration in these coefficients, for example.
After the analog/digital converter 3, the digitized fault current signal is fed to a filter path 50 and, in addition, to a transformation path 51, with, roughly speaking, the low-frequency component of the fault current signal, e.g., in the range less than 400 Hz, being processed in the filter path 50 and the high-frequency component of the fault current signal, in the range greater than 400 Hz, being processed in the transformation path 51. For this purpose, the fault current analysis unit comprises at least one filter unit 15 and one transformation unit 5, in which the fault current signal produced in the device for correctly recording the signal of the fault current may be transformed from the time range into an image range, preferably into the frequency range.
Figure 2 shows a simplified block diagram of the residual current circuit breaker shown in Figure 1. The filter(s) used in the filter path 50 may be tailored to the properties of the measured fault current signal through determination in a configuration operation described in the following. In the transformation path 51, the higher signal frequencies of the measured fault current signal are processed through mathematical transformation.
Alternatively, multiple parallel filter paths 151, 152, 15n, which together cover a specific frequency range, may be used, as shown in Figure 3.
In the exemplary embodiment shown in Figure 1, the filter unit is formed by a filter unit having low-pass characteristic 15, whose output is connected to a signal evaluation unit, which is implemented in Figure 1 as a unit for calculating the effective value 16 of the filtered fault current signal. For example, 0 Hz to 400 Hz may be implemented as the passband, the input of the filter unit having low-pass characteristic 15 being connected to the output of the analog converter 3. The filter unit 15 is preferably implemented as a digital filter, the scanning and quantification of the fault current signal may also alternately be performed therein and the analog converter 3 may thus be dispensed with. An analog design of the filter unit 15 is also possible, but automatic tuning thereof, as is described in the following, is then connected with difficulties. In Figure 1, this automatic tuning of the filter unit 15 is performed via a tuning input which is connected to a signal configuration unit 7.
The unit for calculating the effective value 16, which is connected to the output of the filter unit 15, calculates the effective value of the digitized and filtered fault current signal and outputs it at its output which is connected to an input of a summation unit 14. The filter path ends at this point and discharges into the summation unit 14, whose output is connected to a maximum value monitoring device 17, which is connected via a logical OR element 18 to the network disconnection unit 20, this maximum value monitoring device 17 actuating the network disconnection unit 20 if a predefinable limiting value is exceeded. In this way, the consumer is disconnected from the power supply network In another variation according to the present invention, the signal evaluation unit 16 may be implemented as a unit for calculating the peak value or as a unit for calculating the average value or the like. However, since it is currently typical to fix fault current limiting values as effective values, in the exemplary embodiment shown in Figure 1, the signal evaluation unit is implemented as a unit for calculating the effective value.
In the transformation path 51, an amplifier 4 is positioned first, whose input is connected to the output of the analog/digital converter 3 and whose output is connected to the input of the transformation unit 5, which transforms the fault current signal from the time range into the frequency range.
The amplifier 4 has a control input in Figure 1, via which its amplification factor as with amplifier 2 may be adjusted by the correction unit 45. This influencing ability may be left out or provided at another point.
In the exemplary embodiment shown Figure 1, the transformation unit is formed by a Fourier transformation unit 5, particularly a discrete Fourier transformation unit, which may preferably be implemented with the aid of fast Fourier transformation (FFT). The time signal is transformed in this case into a frequency spectrum.
However, other transformation methods may also be applied, so that the transformation unit may just as well be formed by a Laplace transformation unit, particularly a discrete Laplace transformation unit. The Laplace transformation represents a generalization of the Fourier transformation, whose discrete version represents the z transformation.
The Gabor transformation and the wavelet transformation offer further possibilities which allow statements to be made about the time behavior of the frequency spectrum of the fault current signal. With Fourier transformation, no statement may be made about the temporal behavior of the signal spectrum.
In the exemplary embodiment shown in Figure 1, a changeover switch 60 is provided at the output of the Fourier transformation unit 5, which is shown in its normal setting, corresponding to the normal operation of the residual current circuit breaker according to the present invention. A correlation unit 8, which is connected to a unit for storing at least one comparative spectrum 12, is connected between the output of the transformation unit and the input of a spectral evaluation unit 11.
The signal produced in the Fourier transformation unit 5 is fed to the correlation unit 8 connected thereto, in which a comparison of the frequency spectrum of the current fault current signal to one or more stored frequency spectra is performed.
The transformation unit 5 is connected via the correlation unit 8 to the spectral evaluation unit, which is implemented in Figure 1 as a unit for calculating the effective value of the frequency spectrum 11, whose output is connected to a further input of the summation unit 14.
The second setting of the changeover switch 60 corresponds to the configuration operation of the residual current circuit breaker according to the present invention. During configuration operation, the output of the transformation unit 5 is switched to the input of a signal configuration unit 7, which is connected to a memory input of the unit for storing at least one comparative spectrum 12.
Configuration operation setting (not shown in Figure 1) of the changeover switch Configuration operation (Figure 4) is used for calibrating the residual current circuit breaker according to the present invention and for detecting the signal spectra possible in operation. For this purpose, load oscillations are produced in the power supply network 40, in that, for example, different consumers connected to the power supply network are activated and deactivated. During the configuration operation, the spectrum of the fault current arising during normal operation is measured and stored, taking the applicable norms into consideration, in an actual signal memory 9, which is connected between the signal configuration unit 7 and the unit for storing the comparative spectrum 12.
Since errors may occur while measuring the comparative spectrum, which may result in the permissible maximum values, which may be fixed in a norm, for example, being exceeded, the maximum tolerable norm values are stored in the maximum value table 10, which are used to determine the actual comparative values which serve as the basis for the comparison in the comparative memory unit 12. The actual signal memory 9 and the maximum value table 10 may be contained in the comparative memory unit 12.
The valid comparative values which are used for the comparison are also stored in the comparative memory unit 12, however. These are formed by delimiting the spectrum stored in the actual signal memory 9 through the normdependent values from the maximum value table The values stored in the comparative memory unit 12 are used in normal operation for comparison with the spectrum determined from the transformation path 51 and, in addition, for setting the digital filter 15 having low-pass characteristic in the filter path 50, which may generally also be composed from multiple filters having bandpass behavior connected in parallel (Figure The setting is performed via the signal configuration unit 7, in which the signal transformed in the Fourier transformation unit 5 is processed and analyzed and the parameters for modifying the filter coefficients of the digital filter 15 having the low-pass characteristic are fixed.
If the maximum permissible values of the signal spectrum are exceeded in configuration operation, the comparative memory unit 12 performs an emergency triggering of the network disconnection unit 20. For this purpose, an emergency triggering output of the comparative memory unit 12 is connected to the logical OR element 18. This prevents values contrary to the norms from being used for comparison and, in addition, a defective system from remaining in operation. A message is output to a control unit 19, which then interrupts the configuration operation.
The control unit 19 also outputs correction factors and control commands from the values of the PID regulator 43, the signal configuration unit 7, external operating elements 26, and an external PC 25, which accesses the system via a graphic user interface (GUI). The user also has the capability of manually modifying the comparative values in the framework of the permissible limiting values from the corresponding norms and the filter parameters of the low-pass filter A further function of the control unit 19 is activating the changeover switch 60, via which one may change over between configuration operation and normal operation. Because of the frequency resolution and the achievable bandwidth, the sampler rates and measurement duration of the different modes of operation are also adjusted by changing over the changeover switch Normal operation setting (shown in Figure 1) of the changeover switch In normal operation (Figure the fault current signal is measured continuously and fed to the filter path 50 and the transformation path 51. Signal components having low frequencies are transmitted and/or damped by the filter in accordance with the set filter coefficients. Signal components having high frequencies are converted in the transformation path 51 via the Fourier transformation unit into a frequency spectrum which is compared in the correlation unit 8 to the values measured in configuration operation and stored in the comparative memory unit 12.
The difference between the frequency spectrum of the current measured fault current signal and the comparative spectrum is output at the output of the correlation unit 8, the effective value of this output signal is calculated in the spectral evaluation unit 11 and added in the summation unit 14 to the low-pass signal evaluated by the unit for calculating the effective value 16. The maximum value monitoring device 17 connected to the output of the summation unit 14 makes a decision about a triggering and, if necessary, actuates the network disconnection unit All filtering tasks except for the anti-aliasing function calculations of the effective value (RMS), mathematical transformations, spectral comparison, and maximum value monitoring, as are implemented in the function block 100, may be performed in an integrated digital signal processor (DSP), ASIC, or microcontroller (pC).
A communication unit 13 connected to the maximum value monitoring device 17 allows monitoring of the configuration in normal operation and the values determined in normal operation and general system parameters, for example, via a modem and further interfaces, ethernet connection, radio modules, or the like.
If the maximum value is exceeded, for example, the consumer is disconnected from the power supply network 40 by actuating switch 20 and a corresponding message is relayed to the communication unit 13, which in the simplest case may be an LED or a buzzer.
Furthermore, the value which led to exceeding the maximum value may be output continuously to the communication unit 13, in order to be able to continuously monitor the system externally.
In Figure 1, an optional correction function unit 6 is positioned between the output of the Fourier transformation unit 5 and the input of the correlation unit 8, which may perform operations via a system function such as forming an absolute value, squaring a spectrum, or splitting off the imaginary part.
In the correlation unit 8, the current measured spectrum is compared to the values measured in configuration operation and stored in the comparative memory unit 12. In the exemplary embodiment shown in Figure 1, the comparison comprises a simple subtraction, but it may also be performed through a different correlation function. A measure of the dissimilarity of the two signals compared in the correlation unit is determined.
In a further variation of the present invention, which is shown in Figure 6, the entire frequency range is covered by filter units 101, 102, 10n having bandpass characteristic connected in parallel, so that the fault current information may be obtained from the sum of the outputs of the filter units 101, 102, The transformation part is now only used for determining filter coefficients. The inputs for setting these filter coefficients of the filter units 101, 102, 10n are connected to corresponding outputs of the signal configuration unit 7, which is connected to the transformation unit 5. The outputs of the filter units 101, 102, 10n are each connected via a signal evaluation unit 116 to inputs of a summation unit 114 and the output of the summation unit 114 is connected to the maximum value monitoring device 17, which is connected to the network disconnection unit 20. In normal operation, the embodiment shown in Figure 6 thus operates only in the time range.
The object of the present invention is also a method for fault current monitoring of a power supply network 40, in which a network disconnection unit 20 is actuated as soon as it is determined a fault current measured value derived from a fault current measurement has exceeded a maximum value.
First, the signal of the fault current is imaged correctly, the correct signal of the fault current is transformed from the time range into the frequency range, and, from the resulting spectrum, either a partial amount of the fault current measured value is calculated and/or the setting of the filter coefficients of at least one low-pass filter for filtering the correct signal of the fault current is determined, the fault current measured value or a partial amount thereof being calculated from the output signal of the at least one low-pass filter.
Claims (18)
1. A residual current circuit breaker having a unit for detecting a fault current within an electrical power supply network and a network disconnection unit, the unit for detecting a fault current including a device for correctly recording the signal of the fault current, which may be coupled to the power supply network, and the unit for detecting a fault current including a fault current analysis unit for spectral characterization of the fault current, which is connected to the network disconnection unit, characterized in that the fault current analysis unit includes at least one filter unit having a preferably low-frequency bandpass characteristic for filtering the fault current signal, and a transformation unit, for transforming the fault current signal produced in the device for correctly recording the signal of the fault current from the time range into an image range, preferably into the frequency range.
2. The residual current circuit breaker according to Claim 1, characterized in that the unit for detecting a fault current also includes a unit for scanning and quantifying the fault current, preferably an analog/digital converter.
3. The residual current circuit breaker according to Claim 2, characterized in that the unit for detecting a fault current also includes an anti-aliasing filter.
4. The residual current circuit breaker according to one of Claims 1 through 3, characterized in that the device for correctly recording the signal of the fault current is formed by a Forster probe, whose output is connected to a regulator unit, which compensates the output signal applied at the output of the Forster probe to zero.
The residual current circuit breaker according to Claim 4, characterized in that a modulator is provided for pre-magnetization of the Forster probe.
6. The residual current circuit breaker according to Claim 1 through 3, characterized in that the device for correctly recording the signal of the fault O current is formed by shunts, Hall-effect devices, or combinations of magnetic and N Hall-effect devices.
7. The residual current circuit breaker according to one of Claims 1 through 6, characterized in that the at least one filter unit is formed by a filter unit having low- pass characteristic, whose output is connected to a signal evaluation unit, preferably a unit for calculating the effective value of the filtered fault current O signal, the transformation unit is connected to a spectral evaluation unit, N preferably a unit for calculating the effective value of the frequency spectrum, and 0 the output of the signal evaluation unit and the output of the spectral evaluation unit are connected to inputs of a summation unit and the output of the summation unit is connected to a maximum value monitoring device, which is connected to the network disconnection unit, this maximum value monitoring device actuating the network disconnection unit if a predefinable limiting value is exceeded.
8. The residual current circuit breaker according to one of Claims 1 through 7, characterized in that the transformation unit is formed by a Fourier transformation unit, particularly a discrete Fourier transformation unit.
9. The residual current circuit breaker according to one of Claims 1 through 7, characterized in that the transformation unit is formed by a Laplace transformation unit, particularly a discrete Laplace transformation unit.
The residual current circuit breaker according to one of Claims 1 through 7, characterized in that the transformation unit is formed by a Gabor transformation unit or a wavelet transformation unit, which allows statements about the time behavior of the frequency spectrum of the fault current signal.
11. The residual current circuit breaker according to one of Claims 7 through characterized in that a correlation unit is connected between the output of the transformation unit and the input of the spectral evaluation unit, which is connected to a unit for storing at least one comparative spectrum. O
12. The residual current circuit breaker according to one of Claims 1 through N 11, characterized in that the output of the transformation unit may be switched to c the input of the signal configuration unit, which is connected to a memory input of 0 the unit for storing at least one comparative spectrum and to an input of the at least one filter unit for setting filter coefficients.
S13. The residual current circuit breaker according to one of Claims 1 through O 12, characterized in that the at least one filter unit is formed by two or more filter 1 units having bandpass characteristic connected in parallel, which have inputs for Ssetting filter coefficients and whose outputs are each connected via a signal Sevaluation unit to inputs of a summation unit and the output of the summation unit is connected to a maximum value monitoring device, which is connected to the network disconnection unit, this maximum value monitoring device actuating the network disconnection unit if predefinable limiting value is exceeded, and the transformation unit is connected to a signal configuration unit, whose outputs are connectable to the inputs for setting filter coefficients.
14. A method for fault current monitoring of a power supply network, in which a network disconnection unit is activated as soon as it is determined a fault current measured value derived from a fault current measurement has exceeded a maximum value, characterized in that the correct signal of the fault current is transformed from the time range into the image range, preferably into the frequency range and, from the resulting spectrum, either a partial amount of the fault current measured value is calculated and/or the setting of the filter coefficients of at least one filter having bandpass characteristic for preferably low- frequency filtering of the correct signal of the fault current is determined, the fault current measured value or a partial amount thereof being calculated from the output signal of the at least one low-pass filter.
The method according to Claim 14, characterized in that the spectrum of the fault current signal is compared to at least one stored comparative spectrum.
16. The method according Claim 14 or 15, characterized in that the fault current measured value is produced from the partial amount of the fault current measured value calculated from the spectrum and the partial amount of the fault Scurrent measured value calculated from the at least one filter having bandpass o characteristic. 0
17. A residual current circuit breaker substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings. C
18. A method for fault current monitoring of a power supply network Csubstantially as herein described with reference to any one of the embodiments of c the invention illustrated in the accompanying drawings. WATERMARK PATENT TRADE MARK ATTORNEYS P24909AU00
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ATA801/2002 | 2002-05-27 | ||
| AT8012002A AT412047B (en) | 2002-05-27 | 2002-05-27 | FAULT CIRCUIT BREAKER |
| PCT/AT2003/000147 WO2003100938A1 (en) | 2002-05-27 | 2003-05-20 | Residual current circuit breaker |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU2003229345A1 AU2003229345A1 (en) | 2003-12-12 |
| AU2003229345B2 true AU2003229345B2 (en) | 2007-11-01 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2003229345A Ceased AU2003229345B2 (en) | 2002-05-27 | 2003-05-20 | Residual current circuit breaker |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP1512207B1 (en) |
| JP (1) | JP2005536008A (en) |
| CN (1) | CN1656659B (en) |
| AT (1) | AT412047B (en) |
| AU (1) | AU2003229345B2 (en) |
| DE (1) | DE50301511D1 (en) |
| NO (1) | NO334263B1 (en) |
| TN (1) | TNSN04231A1 (en) |
| WO (1) | WO2003100938A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8023236B2 (en) | 2009-03-18 | 2011-09-20 | Hamilton Sundstrand Corporation | Precision ground fault detection for aircraft human body protection |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10237342B4 (en) * | 2002-08-14 | 2004-07-29 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method and device for monitoring residual current in an electrical AC network |
| EP2568557B1 (en) | 2011-09-07 | 2014-02-26 | Siemens Aktiengesellschaft | Method of operating a residual current circuit breaker and residual current circuit breaker for a frequency converter |
| CN103219703B (en) * | 2013-04-07 | 2015-08-26 | 国家电网公司 | Anti-low voltage inverse power transmission earth leakage protective device |
| DE102014100068B4 (en) * | 2013-10-06 | 2020-06-18 | Bajog Electronic Gmbh | Method and device, namely handheld network analysis device, for the rapid and simple detection of line-based interference in the lower frequency range on power supply network lines |
| DE102014221042A1 (en) * | 2014-07-04 | 2016-01-07 | Siemens Aktiengesellschaft | Residual current device for leakage current detection |
| DE102015218914A1 (en) * | 2015-06-30 | 2017-01-05 | Siemens Aktiengesellschaft | Fire protection switch |
| DE102016202021B3 (en) * | 2016-02-10 | 2017-03-23 | Bender Gmbh & Co. Kg | Method and devices for detecting a break in a protective conductor connection |
| CN113363951B (en) * | 2021-05-21 | 2023-10-31 | 珠海格力电器股份有限公司 | Direct current residual current protector, protection method and direct current power supply system |
| DE102023207065B3 (en) * | 2023-07-25 | 2024-10-02 | Siemens Aktiengesellschaft | Switch with residual current monitoring as well as control cabinet and residual current monitoring system with such a switch |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001095451A2 (en) * | 2000-06-09 | 2001-12-13 | Siemens Aktiengesellschaft | Software-controlled evaluation of fault currents for protection and monitoring systems |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5512832A (en) * | 1993-10-15 | 1996-04-30 | The Texas A & M University System | Energy analysis fault detection system |
| DE4430246C2 (en) * | 1994-08-25 | 1997-08-28 | Siemens Ag | Method and arrangement for monitoring power supply networks |
| US6088205A (en) * | 1997-12-19 | 2000-07-11 | Leviton Manufacturing Co., Inc. | Arc fault detector with circuit interrupter |
-
2002
- 2002-05-27 AT AT8012002A patent/AT412047B/en not_active IP Right Cessation
-
2003
- 2003-05-20 WO PCT/AT2003/000147 patent/WO2003100938A1/en active IP Right Grant
- 2003-05-20 AU AU2003229345A patent/AU2003229345B2/en not_active Ceased
- 2003-05-20 JP JP2004508477A patent/JP2005536008A/en active Pending
- 2003-05-20 DE DE50301511T patent/DE50301511D1/en not_active Expired - Lifetime
- 2003-05-20 CN CN03812407.6A patent/CN1656659B/en not_active Expired - Fee Related
- 2003-05-20 EP EP03722040A patent/EP1512207B1/en not_active Expired - Lifetime
-
2004
- 2004-11-23 TN TNP2004000231A patent/TNSN04231A1/en unknown
- 2004-12-23 NO NO20045626A patent/NO334263B1/en not_active IP Right Cessation
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001095451A2 (en) * | 2000-06-09 | 2001-12-13 | Siemens Aktiengesellschaft | Software-controlled evaluation of fault currents for protection and monitoring systems |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8023236B2 (en) | 2009-03-18 | 2011-09-20 | Hamilton Sundstrand Corporation | Precision ground fault detection for aircraft human body protection |
Also Published As
| Publication number | Publication date |
|---|---|
| NO20045626L (en) | 2004-12-23 |
| HK1075751A1 (en) | 2005-12-23 |
| CN1656659B (en) | 2011-10-05 |
| NO334263B1 (en) | 2014-01-20 |
| CN1656659A (en) | 2005-08-17 |
| TNSN04231A1 (en) | 2007-03-12 |
| EP1512207A1 (en) | 2005-03-09 |
| ATA8012002A (en) | 2004-01-15 |
| EP1512207B1 (en) | 2005-10-26 |
| AT412047B (en) | 2004-08-26 |
| DE50301511D1 (en) | 2005-12-01 |
| AU2003229345A1 (en) | 2003-12-12 |
| WO2003100938A1 (en) | 2003-12-04 |
| JP2005536008A (en) | 2005-11-24 |
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