WO2007144789A2 - Instrument and method for measuring partial electrical discharges in an electrical system - Google Patents
Instrument and method for measuring partial electrical discharges in an electrical system Download PDFInfo
- Publication number
- WO2007144789A2 WO2007144789A2 PCT/IB2007/051293 IB2007051293W WO2007144789A2 WO 2007144789 A2 WO2007144789 A2 WO 2007144789A2 IB 2007051293 W IB2007051293 W IB 2007051293W WO 2007144789 A2 WO2007144789 A2 WO 2007144789A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- instrument
- pulses
- processing
- signal
- wave form
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
- G01R19/2513—Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
Definitions
- the present invention relates to an instrument and a method for measuring partial electrical discharges in an electrical system, the instrument comprising: - an input stage set up to receive an analogue signal representing one or more pulses of partial discharges to be measured and to generate at its output a digital representation of the entire wave form of said one or more pulses, - an output stage set up to transfer data in digital shape at the output from the instrument.
- the technical sector of the present invention is that of the diagnostics of electrical systems (in particular in high voltage), by the measurement / processing of partial electrical discharges and possibly other quantities.
- a partial discharge is an electrical discharge that involves a limited portion of an insulator of an electrical system, therefore it does not cause the immediate failure of the system, but its progressive degradation.
- partial discharges have, for their nature, a development that is substantially limited to a defect of the insulating system.
- diagnostic techniques based on the measurement and interpretation of partial discharges are among the most promising and they are widely studied in scientific research, because the study of partial discharges allows to investigate the nature of the defects of the insulating system in which the discharges themselves reside.
- the present invention relates, in particular but not exclusively, to electrical measuring techniques, which consist, as is well known, of measuring the current pulses that travel through a measuring circuit coupled with the electrical system in question.
- Said measured current pulses (hereafter called discharge pulses, for the sake of simplicity), have a time development, which depends on the dynamics with which the partial discharges occur (i.e. on the physics of the discharge phenomena) and on the nature of the means that the measured pulses traverse, in their path from the discharge site (in which the discharges originate) to the measurement site.
- the time development of the discharge pulses consisting of the wave form of the pulses themselves, comprises information that is precious from the diagnostic viewpoint, both with regard to the physical phenomena associated with the discharges (correlated to the nature of the defects of the insulating system), and the nature of the medium which the measured pulses traverse (correlated to the location of the defects within the insulating system).
- a loss of information that is essential for a subsequent evaluation of the signals for diagnostic purposes (a loss of information can be constituted, for example, by a failure to measure an impulse, or by a failure to measure the wave form of a pulse);
- noise may be superposed to the discharge signals, or signals due to different sources may be mutually superposed, with a consequent objective difficulty in interpreting the results, given the impossibility to perform significant statistical processing on heterogeneous data and/or on data that are not pertinent to the individual phenomena to be evaluated.
- the signals associated to the partial discharges are electrical impulses having a very high frequency content (they have up-ramps in the order of nanoseconds, or tens of nanoseconds) and, in certain cases, their repetition rate is quite high (e.g., hundreds of thousands of pulses per second).
- peak detectors typically, narrow / selective band instruments
- oscilloscopes typically, wide band instruments.
- peak detectors are not able to record the time dynamics of the detected pulse, because they do not perform an actual sampling of the signal, unlike oscilloscopes, which instead do perform said sampling.
- peak detectors are generally provided with a relatively narrow / selective band in order to be robust with respect to unwanted signals, in particular background noise.
- Peak detectors are instruments that provide indications solely about the phase of occurrence and the amplitude of PD
- the amplitude of a PD is generally obtained passing the analogue signal through an FQI (quasi-integrator filter) and, hence, measuring the peak value.
- FQI quadrati-integrator filter
- the FQ ⁇ is constituted by an analogue electrical grid.
- the output signal from the FQI is displayed on an oscilloscope.
- the available information is the known Lissajous figure, made available by the oscilloscope.
- the FQI is still obtained by means of an analogue electrical grid and sent to a peak detector, also analogue, which provides the amplitude of the PD.
- the electronics of the instrument converts the amplitude signal of the PD (output by the peak detector) from analogue to digital.
- the available information is the set of the possible representations that can be obtained knowing
- phase and amplitude of the PDs e.g., the known phase/amplitude pattern.
- the signal is filtered for the purpose of avoiding the known phenomenon of aliasing and, subsequently, it is sampled (analogue/digital transformation).
- the chain for calculating the amplitude of the PD (FQI filtering and detection of the peak of the signal output by the FQI) is obtained in this instruments it) by means of numeric algorithms.
- the available information is the set of the possible representations that can be obtained knowing phase and amplitude of the PDs.
- said quasi-integrator filter FQI returns a signal whose information content (useful for a subsequent diagnosis of the electrical system to be evaluated) consists solely of a peak value of the wave form of the input is signal, said value corresponding to the amplitude of the SP.
- Peak detectors entail a drastic loss of information in the detected signals, due to the strong compression of the information associated with the partial discharge signal, due to the fact that they do not sample the detected signal and to the presence of the quasi-integrator filter. In particular, they do not allow to acquire significant information about the wave form of the pulses of the detected partial discharges. Therefore, they do not allow to separate (especially in automatic, unsupervised fashion) the noise from the discharge signals and, to a greater extent, the discharge signals coming from different sources.
- peak detectors have a limitation in the phase of attributing the sign to the measured amplitude for a pulse, said sign having considerable importance, as is well known, in interpreting the results of the measurements (which are carried out, in most applications, subjecting the electrical components in question to alternating voltage).
- peak detectors do not allow to verify said attribution (possibly by performing the sign attribution step again, on the basis of a different criterion / calculation algorithm).
- an additional limitation is associated with the instruments that detect pulses using a narrow band; a limited bandwidth could alter the time dynamic of the pulse, especially when the pulse has very rapid changes over time.
- instruments which, in addition to the amplitude of the pulse, are able to measure the time width of the pulse itself; such instruments are substantially peak detectors provided with a plurality of comparators (with different thresholds). Therefore, said instruments carry out, in fact, a sort of sampling (in certain case, with variable frequency).
- said instruments do not allow to detect the wave form of the pulse, i.e. the profile of the pulse amplitude over time, said wave form instead having fundamental importance for the purposes of a subsequent diagnostic evaluation of the acquired data.
- oscilloscopes allow to measure discharge signals in wide band, and Io acquire the entire wave form of the detected pulses.
- the oscilloscope/computer system is penalising, not only from the cost viewpoint, but also from the performance viewpoint, because of the need to transfer enormous quantities of data from the oscilloscope to the computer.
- the problems deriving from the need to transfer data from the oscilloscope to the computer the following should also be noted.
- the oscilloscope / computer system does not allow to measure different signals having mutually different time dynamics in efficient, optimised fashion, for the purposes of a diagnostic evaluation of an electrical system by analysing partial discharge signals.
- An object of the present invention is to eliminate the aforesaid drawbacks and to make available an instrument for measuring pulses of partial electrical discharges that enables to maximise the information content of the measured signals, in a particularly rapid and effective manner (minimising dead time). Another object of the present invention is to minimise noise interference and to separate the effects due to different sources when the various measured pulses have mutually different shape. Another object of the present invention is to make available an instrument for measuring pulses of partial electrical discharges able to be used without any external intervention / supervision by an operator.
- Another object of the present invention is to make available an instrument for measuring pulses of partial electrical discharges thai is efficient and economical. Said objects are fully achieved by the instrument of the present invention, which is characterised by the content of the claims set out below and in particular in that it comprises data processing means operatively associated both to the input stage and to the output stage to receive said digital representation of the entire wave form of said one or more pulses, to extract the value of predetermined parameters relating to the wave form of said one or more pulses and to transfer to the output stage a processed digital signal comprising said values, the processing means being able to operate substantially in real time, i.e. with no need for an intermediate data storage memory.
- Another object of the present invention is to make available a method for measuring partial electrical discharges in an electrical system, which enables to maximise the information content of the measured signals and which, at the same lime, can be implemented in simple, effective fashion, also in a totally automatic manner. Said object is fully achieved by the method of the present invention, which is characterised by the content of the claims set out below and in particular in that it comprises the following steps:
- Storage memory means a memory able to (or, from the hardware viewpoint, a memory managed in such a way as to) contain a data item for a potentially unspecified time, to be able to retrieve it subsequently (at any time) and process it.
- a mass storage memory e.g.
- a RAM memory can, depending on how it is managed, constitute a storage memory (as clarified above), or, alternatively, it can constitute a buffer (temporary memory), i.e. a means that enables to slow down the data stream (at a certain point of the path travelled by the data from the input to the output), but without interrupting it. Therefore, real time processing means that the processing takes place during the passage of data from an input to an output in a substantially continuous stream, which may entail a slowing of the data stream, through a temporary accumulation of the data in a substantially volatile memory, but may not entail an interruption of the stream.
- FIG. 1 schematically shows an instrument according to the present invention
- - figure 2 shows the instrument of figure ⁇ according to an embodiment variant
- - figure 3 schematically shows a detail of the instrument of figure 1 ;
- T Equivalent duration
- Coupler a device able to draw a discharge signal from the examined system; e.g., a high voltage capacitor connected in series to a resistor: the capacitor blocks high voltage at 50/60 Hz and allows the passage of the discharge signal, the discharge signal is measured as the voltage drop over the resistor.
- Anti-aliasing filter a filter used in sampled data systems to convert the signal from analogue to digital in a correct manner. It is well known that if the analogue signal contains components whose frequency exceeds half the sampling frequency, a distortion known as aliasing can occur. Therefore, the anti-aliasing fiiter is a low- pass filter that removes the possible components of the analogue signal whose
- Segment sequence of samples representing the profile over time (wave form) of the individual event to be measured (discharge pulse). Each segment comprises the number of samples (time duration) that form the pulse and the number of pre-trigger samples (pre-trigger time).
- Minimum Peak Dead Time minimum time interval between the end of the acquisition of a segment and the moment when the subsequent segment can be acquired. It depends on the speed of the part of the system between an input stage and a first buffer available for the segments or other extracted predetermined parameters.
- Minimum Continuous Dead Time time interval between the end of the acquisition of a segment and the moment when the subsequent segment can be acquired, measured in the stationary condition of continuously acquired segments. It depends on the speed of the entire system and of the recipient of the segments or of the parameters extracted thereby.
- MSBL Maximum Segment Burst Length
- the numeral 1 designates an instrument for detecting partial electrical discharges in an electrical system.
- the instrument 1 is operatively connected to the electrical system under evaluation through a measurement circuit comprising at least a coupler, according to the prior art in the sector of partial electrical discharge measurements.
- the instrument 1 comprises an input stage 2, set up to receive an analogue discharge signal 3, i.e. an analogue signal representing one or more pulses of partial discharges to be measured, and (set up) to generate at its output a digital representation of the entire wave form of said one or more pulses. Moreover, the instrument 1 comprises an output stage 4, set up to transfer data in digital form at the output from the instrument.
- an analogue discharge signal i.e. an analogue signal representing one or more pulses of partial discharges to be measured
- an output stage 4 set up to transfer data in digital form at the output from the instrument.
- the instrument 1 also comprises, originally, data processing means 5 operatively associated both with the input stage 2 and with the output stage 4 to receive said digital representation of the entire wave form of said one or more pulses, extract the value of predetermined parameters relating to the wave form of said one or more pulses and transfer to the output stage 4 a processed digital signal comprising said values.
- the processing means 5, originally, are able to operate substantially in real time, i.e. with no need for a memory for the intermediate storage of the data.
- the numeral 6 designates an analogue synchronism signal, representing a voltage applied to the electrical system.
- said synchronism signal 6 is not essential for measuring partial discharge (PD) signals, but it is useful in a subsequent step of evaluating the measured data for diagnostic purposes, in the case of electrical systems operating in alternating current.
- ⁇ combined measurement of the PD signals and of the synchronism signal enables to obtain a correlation between each partial discharge event with the value that the voltage applied to the electrical system had in the instant when the event took place (it should be noted that to said correlation are associated parameters called "phase parameters").
- the instrument 1 is provided with a stage for measuring said analogue synchronism signal 6, originally comprising, in a preferred embodiment (the one illustrated), a block 7 for digitising said analogue signal, connected to a block 8 for generating a base of synchronism times.
- said block 8 for generating a base of synchronism times derives from the samples coming from the digitising block 7 the time elapsed since the last passage of the synchronisation signal through zero. This time is saved together with every segment to obtain, relating it to the period of the synchronism signal, the phase parameters.
- Said block 8 is implemented, in the preferred embodiment, in hardware mode, in programmable logic, but it can also be implemented via software. It is specified that, with regard specifically to the present invention, every reference made to "software” means a set of programming instructions residing in a storage memory within the apparatus, otherwise known as firmware.
- stage of measuring the synchronism signal 6 is a part, from the logical-functional viewpoint, of the input stage 2.
- the block 7 for digitising the analogue synchronism signal 6 is shown in detail (in schematic form) in figure 4.
- the block 7 comprises:
- an overvoltage (ESD) protection element 9 of a substantially known kind, able to prevent overvoltages or electrical discharges from damaging the subsequent stages of the instrument;
- the synchronisation logic can be varied at will to accommodate particular signals (e.g. OWTS, or cases in which the applied voltage has damped oscillations) without changing the hardware.
- the instrument 1 also comprises a block 12 for digitising the discharge signal 3, i.e. the analogue signa! correlated to the partial discharges taking place in the electrical system.
- an overvoltage protection element 13 of a substantially known kind, able to prevent overvoltages or electrical discharges from damaging the subsequent stages of the instrument;
- an analogue gain control stage 14 (of a substantially known kind);
- an analogue/digital converter 16 (of a known kind).
- the gain control stage 14 is able to adapt the amplitude of the input signal 3 to the interval of voltages allowed by the analogue/digital converter 16, in such a way as to maximise its dynamics and to prevent saturation phenomena (saturation takes place when the input signal to said converter exceeds the maximum or minimum level of voltage it is able to sample).
- the digitisation block 12 is able to operate, in wide band, to receive at its input the analogue discharge signal 3, outputting a digital signal constituted by a continuous sequence of samples 17. It should be noted that the digitisation block 12 preferably operates at a constant sampling rate (e.g. 100 MS/s).
- the instrument 1 is also provided with a plurality of acquisition parameters 18, configurable from the outside, necessary for processing the samples 17.
- Said acquisition parameters 18 are stored in the instrument 1 .
- Said acquisition parameters comprise, in particular:
- - acquisition time defined by the number of samples constituting a segment, i.e. a digital signal representing the profile over time (wave form) of a single partial electrical discharge
- - pre-trigger time defined by the number of samples preceding a trigger event
- the digitisation block 12 is connected both to a pre-trigger deposit 19 and to a trigger generator 20.
- the pre-trigger 19 deposit is constituted by a circular buffer, that maintains a number samples equal to the pre-trigger time for the formation of a subsequent segment; it is preferably implemented via hardware in programmable logic.
- the trigger generator 20 originally comprises a double threshold comparator (unlike known trigger generators that comprise a single threshold comparator), receiving as an input a predetermined reference value for a trigger threshold 21.
- the pre-trigger 19 and the trigger generator 20 receive as an input the signal comprising the samplers 17, output by the digitisation block 12,
- the trigger generator 20 is connected to a trigger selector 22 (of a substantially known type), which in turn is connected to a block 23 for managing the input stage 2.
- the management block 23 receives at its input: - the digital signal output by the trigger selector 22;
- the management block 23 is connected in output to the pre-trigger deposit 19, to operate a managemenl thereof; in practice, the management block 23 recognises and selects, within the uninterrupted stream of the samples 17, segments 25 representing the profile over time (wave form) of the partial discharge signals. Therefore, the segments 25 are selected by the management block 23, at the output from the pre-trigger deposit 19.
- the processing means 5 originally comprise a block 26 for processing / extracting predetermined parameters, relating to the wave form of said one or more PD pulses.
- the block 26 is preferably implemented in logic programmable via hardware (but it can also be implemented via software) and receives the segments 25 at its input.
- the block 26 operates in real time and it has the function of extracting from the samples of a segment 25 the predetermined parameter values.
- said predetermined parameters comprise, for each partial discharge pulse: equivalent duration (T), equivalent bandwidth (W), polarity (i.e. the sign of a first peak of the pulse exceeding, in absolute value, a reference value), amplitude of the pulse, energy of the pulse, together with other quantities obtained by applying various signal processing techniques, such as wavelets.
- said parameters equivalent duration (T) and equivalent bandwidth (W) can be replaced with other parameters similar to them, or they can be calculated in alternative manners with respect to the definitions provided above (which anyway constitute a preferred way to calculate said parameters).
- the extracted parameters contain all the information about the measured PD pulses, linked particularly (but not exclusively) to the wave form of the pulses, useful for a subsequent use of the measured data for diagnostic purposes.
- the instrument 1 acquires and makes available at its output data pertaining to the partial discharge pulses taking place in ihe electrical system in question; said data will then be used to conduct a diagnostic evaluation of the electrical system and/or to be stored, to constitute a knowledge base for the development of diagnostic strategies.
- the data about the partial discharge pulses are to be manipulated, processed, displayed, etc. according to requirements and procedures that, in principle, may not be known or foreseeable ahead of time. Therefore, it is important that the data measured by the instrument 1 be as significant and complete as possible.
- the block 26 receives at its input the segments 25 (i.e. a digital representation of the entire profile over time of the PD pulses), processes them in real time and outputs a compacted digital signal 27, constituted by a representation that is synthetic (hence manageable with particularly short calculation time) but is equally representative of the entire profile over time of the PD pulses.
- the action of the block 26 entails that the segments 25 in themselves are not maintained, with consequent advantage in terms of the quantity of data processed / outputted by the instrument.
- the instrument 1 also provides the possibility of bypassing the block 26, by means of an inhibiting signal sent by the management block 23, so that the segments 25 are outputted by the block 26 without any processing / extraction.
- the processing / extraction block 26 is connected to a buffer 28, i.e. a circular memory, able to store in real time (at the same rate whereat it receives the input data) the compacted digital signal 27 (or the segments 25, if the extraction block 26 is inhibited) to make them available to subsequent stages, which may be operating at different rates.
- the buffer 28 is preferably implemented with logic programmable via hardware (but it can also be implemented via software).
- the buffer 28 interacts with the control element 24, whose function is to determine whether or not to allow the acquisition of a new segment according to the amount of free space in the buffer 28.
- the control element 24 is preferably implemented with logic programmable via hardware (but it can also be implemented via software).
- the buffer 28 is connected with a second processing / extraction block 29, preferably implemented via software (e.g. comprising a DSP, or a microprocessor or a microcontroller or a combination thereof), but also programmable via hardware with programmable logic.
- the function of the second processing / extraction block 29 is similar to that of the processing / extraction block 26; the processing / extraction block 29, operating downstream of the buffer 28, can perform calculations that require more time, without slowing the operation of the instrument 1.
- the processing means 5 originally comprise two distinct processing / extraction blocks 26 and 29 and a buffer 28 interposed between the blocks themselves allows to optimise calculation times and to minimise the Dead Time, while operating in real time, i.e. with no need for a memory in which to store a certain quantity of data, to extract it subsequently. Moreover, in the combined action of the two blocks 26 and 29, the processing / extraction block 26 reduce the quantity of work of the second processing / extraction block 29 and hence reduces Continuous Minimum Dead Time. It should be noted the processing means 5 may also comprise a single processing / extraction block 26, operating in real time, with no need to interpose the buffer 28. It should be noted that the processing means 5 may also comprise further architectures. Two aspects should be specified, with regard to the operation of the processing block and to the management of the data stream.
- the pre-trigger deposit 19 and the buffer 28 constitute memories (whose presence is not indispensable for the purposes of the present invention) that are preferably organised as circular, managed according to a FIFO logic; i.e., said memories input and output data in the same order in which they are received, continuously, without interruptions to the data stream. Therefore, the function of the memory is to operate a temporary slow-down of the data stream.
- the buffer 28 constitutes means for (temporarily) slowing the data stream from said input stage to said output stage.
- the processing blocks 26 and 29 are able to derive parameters on the basis of the entire wave form of the partial discharge pulse.
- the processing block 26 does not operate simultaneously on all samples corresponding to a pulse, but on one sample at a time (sequentially), performing a sequence of passages (in the calculation of said predetermined parameters) and retaining at each passage a partial result in its own register, said partial result being updated from time to time, until it assumes the definitive value for said predetermined parameter, after the last sample relating to the pulse has been processed.
- This implementation aspect contributes to the possibility of deriving in real time (with particularly reduced dead time values) parameters based on the entire wave form of the measured partial discharge pulses.
- the output stage 4 of the instrument 1 comprises a communication interface 30, able to encapsulate the data from and to the instrument 1 on a two-directional communication bus 31 , preferably stream-oriented.
- two-directional communication oriented to the stream between A and B means any system that allows to transfer two data streams, one from A to B, the other one from B to A, such that the data reach the recipient in the same order with which they were sent and that the two streams are substantially simultaneous and continuous.
- the physical implementation can bear on non continuous (packet) systems and/or non simultaneous systems (half-duplex) and/or non ordered systems, but in this case too it is possible to continue to speak of data streams, because appropriate protocols and/or buffers can return the communication to conditions of continuity, simultaneity and order.
- Minimum Continuous Dead Time can depend on the transfer capacity of the bus 31 if it is lower than that of the processing / extraction block 29.
- Said bus 31 can comprise, for example, known technical solutions such as RS232, USB, firewire, or Ethernet.
- the communication interface 30 can be implemented both via hardware and via software.
- the preferred embodiment of the invention provides for a TCP/IP socket implementation on Ethernet through a hardware device.
- the instrument 1 also comprises a control logic 32, overseeing all control and synchronisation functions of the software components of the instrument 1 , implemented via software.
- the processing means 5 preferably comprise, originally, a conditioning element 33, inserted between the second processing / extraction block 29 (or the processing / extraction block 26) and the output stage 4, to operate a digital filtering of the processed signal, as a function of the derived values.
- Said conditioning element 33 operating a real time filtering of the measured signal according to said predetermined parameters (correlated to diagnostic evaluations of the electrical system based on the evaluation of the activity of the partial discharges), allows an important advantage, i.e. that of being able to observe a slow phenomenon (characterised by few discharge pulses in the unit of time) for a long time without saturating a memory (possibly connected to the output stage 4, downstream of the instrument 1) with the data relating to another, very intense, concomitant phenomenon (characterised by a relatively high number of discharge pulses or of unwanted signals in the unit of time).
- the extraction element 33 advantageously allows to reject noise or to select pulses belonging to a given discharge phenomenon with respect to other superposed pulses, in real time, on the basis of the wave form of the signals. This enables the instrument 1 to output complete, significant data, with no risk of information loss. Otherwise, if the coarse input analogue signal were measured and digitised (without processing or filtering) and stored in a memory, to carry out all processing operations at subsequent times (e.g. through a computer), there would be the risk of not being able to measure all pulses of interest, given the quantity of information that would have to be managed via software.
- the digitisation block 12, the pre-trigger deposit 19, the trigger generator 20, the trigger selector 22, the management block 23, the processing / extraction block 26 (and possibly the buffer 28 and the second processing / extraction block 29) define a unit, from the logic-functional viewpoint, whereto reference shall be made below as acquisition channel 34
- the instrument 1 comprises a first acquisition channel 34 ⁇ and a second acquisition channel 34B. in the presence of two or more acquisition channels 34, each trigger selector 22 receives and sends control signals 35, interacting with other trigger selectors 22 included in corresponding acquisition channels 34. It should be noted that it is provided for the instrument 1 to be have a plurality of acquisition channels 34.
- Said acquisition channels 34 can be dedicated, for example, to the measurement of partial discharges taking place on different phases of a multiphase electrical system.
- the use is also provided of one or more acquisition channels 34 to measure quantities other than partial discharges, e.g. quantities correlated to environmental factors (e.g. temperature and humidity); in this case, the instrument 1 originally comprises channels dedicated to the detection of PD and slow channels, substantially active in parallel. Note that said channels do not necessarily require the presence of trigger means.
- the present invention also makes available a method for measuring partial electrical discharges in an electrical system. Said method comprises the following steps:
- Said method also comprises a step of measuring an analogue synchronism signal, representing a voltage applied to the electrical system, made available for the processing step.
- a step of digitising said analogue synchronism signal is originally provided.
- the processing step preferably comprises, in turn, the following sub-steps: - first processing of said digital representation of the entire wave form of said one or more pulses,
- the method according to the present invention comprises the following In an input stage 2, an analogue signal 3 representing one or more PD pulses is translated, through a sampling step, into a continuous stream of samples representing the wide band signal to be analysed; the samples are transferred to a trigger generator 20, which observes the signal searching for samples that exceed the set threshold (trigger threshold 21) and generates the trigger event, and a pre-trigger deposit 19, a circular buffer that stores a number of samples equal to the pre-trigger time.
- the pre-trigger deposit 19 presents at the input of a processing / extraction block 26, or directly to a buffer 28, a flow of samples identical to the one it receives, but delayed by a time equal to the pre-trigger time.
- a management block 23 if there is space in the buffer 28, activates the processing / extraction block 26 and, after a time set according to the acquisition parameters 18, it determines the end of a segment 25; the processing / extraction block 26 analyses said flow and extracts predetermined parameters from the segment, which are saved on the buffer 28. If the processing / extraction block 26 is inhibited (by the management block 23), the management block 23 orders the storage on the buffer 28 of the entire segment 25 together with its time co-ordinates (absolute time and time relative to the synchronism signal). It should be noted that said time co-ordinates arc saved (by the processing / extraction block 26 itself) also if the block 26 is not inhibited.
- the present invention makes available an apparatus and a method that allow the following advantages.
- the present invention enables to measure partial discharge pulses with a particularly short Dead Time.
- a Dead Time which is substantially the time in which the system is blind after acquiring a segment, before being able to acquire another one
- a Dead Time allows in the first place to acquire a higher number of PD phenomena at the same time.
- noise e.g. non continuous noise, such as interference between electrical apparatuses
- an acquisition system known in the art does not allow to separate the PD phenomena from each other and/or from noise.
- the possibility of acquiring a great number of data, with no need to store said data in a memory enables to measure and separate the PD phenomena from each other and from noise in real time or also at a subsequent time, by analysing predetermined parameters extracted in real time. Note that said separation can be accomplished within the instrument 1 before the data are outputted, saving on the bandwidth of the communication bus.
- Separating the processing / extraction block in two blocks, 26 and 29, enables to limit dead time to very small values (at least for a certain number of discharges), e.g. below 1 ⁇ s.
- the sense of having a particularly short Dead Time for a certain number of discharges derives from the fact that PD phenomena are typically not distributed uniformly over time, but concentrate in determined time intervals.
- the present invention enables to absorb discharge concentrations without losing them, and then process them when the discharge rate is more limited.
- the instrument 1 integrates in programmable logic everything that works in real time, including the buffer 28, while a remaining part of the calculations is performed by elements implemented via software, or by a DSP, so that the instrument 1 is able to perform substantially any type of calculation, whilst limiting the costs.
- the programmable logic can quickly perform relatively simple operations, whilst the software in DSP can perform any kind of calculation, but typically in a longer time, depending on its cost and on its complexity.
- the division of tasks between the two components enables to obtain excellent performance levels whilst limiting costs and complexity.
- the components implemented in programmable logic and those implemented via software (DSP) always operate simultaneously, because the buffer 28 can be written by the programmable logic (e.g. the processing / extraction block 26) and, simultaneously, read by DSP (e.g. the second processing / extraction block 29); the programmable logic has to stop only when the buffer 28 is full.
- an advantage of the present invention is constituted by the possibility of performing highly complex processing operations on the measured data, in particularly quick and efficient fashion, thanks to the fact that said advanced processing operations (i.e. processing operations that, in themselves, require great expenditure of calculation resources) are performed downstream of the intervention o of the processing / extraction block 26, i.e. on the compacted digital signal 27 in real time. Therefore, the present invention allows to provide a diagnostic evaluation of the evaluated electrical system (e.g. by applying artificial intelligence techniques or any other processing technique applicable substantially in real time to the measured data) substantially in real time.
- the present invention enables to measure and process, in simultaneous and synergetic fashion, signals pertaining to partial discharge pulses and signals pertaining to any other quantity, thanks to the possibility of using a plurality of mutually interacting acquisition channels 34.
- the present invention requires no supervision on an operator's part; 0 therefore, it can be used under any condition, also for monitoring purposes (i.e. for the continuous measurement, extending over an indefinite time, of the discharge signals taking place in the electrical system in question).
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Relating To Insulation (AREA)
- Protection Of Static Devices (AREA)
Abstract
Description
Claims
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
BRPI0712828-2A BRPI0712828A2 (en) | 2006-06-13 | 2007-04-11 | instrument and method for measuring partial discharges in an electrical system |
KR1020097000719A KR101321561B1 (en) | 2006-06-13 | 2007-04-11 | Instrument and method for measuring partial electrical discharges in an electrical system |
ES07735458T ES2391582T3 (en) | 2006-06-13 | 2007-04-11 | Instrument and method to measure partial electrical discharges in an electrical system |
EP07735458A EP2027478B1 (en) | 2006-06-13 | 2007-04-11 | Instrument and method for measuring partial electrical discharges in an electrical system |
KR1020137018182A KR101423753B1 (en) | 2006-06-13 | 2007-04-11 | Instrument and method for measuring partial electrical discharges in an electrical system |
US12/304,410 US8055459B2 (en) | 2006-06-13 | 2007-04-11 | Instrument and method for measuring partial electrical discharges in an electrical system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ITPR2006A000054 | 2006-06-13 | ||
IT000054A ITPR20060054A1 (en) | 2006-06-13 | 2006-06-13 | INSTRUMENT AND PROCEDURE FOR DETECTION OF PARTIAL ELECTRIC DISCHARGES IN AN ELECTRIC SYSTEM |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2007144789A2 true WO2007144789A2 (en) | 2007-12-21 |
WO2007144789A3 WO2007144789A3 (en) | 2008-02-21 |
Family
ID=38669170
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IB2007/051293 WO2007144789A2 (en) | 2006-06-13 | 2007-04-11 | Instrument and method for measuring partial electrical discharges in an electrical system |
Country Status (8)
Country | Link |
---|---|
US (1) | US8055459B2 (en) |
EP (1) | EP2027478B1 (en) |
KR (2) | KR101321561B1 (en) |
CN (2) | CN103809088A (en) |
BR (1) | BRPI0712828A2 (en) |
ES (1) | ES2391582T3 (en) |
IT (1) | ITPR20060054A1 (en) |
WO (1) | WO2007144789A2 (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2010136999A1 (en) | 2009-05-29 | 2010-12-02 | Techimp Technologies S.R.L. | Instrument and method for detecting partial electric discharges in an electric apparatus |
WO2011051910A1 (en) | 2009-10-30 | 2011-05-05 | Techimp Technologies S.R.L. | Device and method for detecting and processing signals relating to partial electrical discharges |
WO2011110986A1 (en) | 2010-03-10 | 2011-09-15 | Techimp Technologies S.R.L. | Instrument and method for detecting partial electrical discharges |
WO2011110984A1 (en) | 2010-03-10 | 2011-09-15 | Techimp Technologies S.R.L. | Instrument and method for detecting partial electrical discharges |
US8055459B2 (en) * | 2006-06-13 | 2011-11-08 | Techimp Technologies S.R.L. | Instrument and method for measuring partial electrical discharges in an electrical system |
WO2014024060A1 (en) | 2012-08-06 | 2014-02-13 | Techimp Technologies S.R.L. | Device for monitoring an activity of partial discharges which occurs in an electrical apparatus |
US8760171B2 (en) | 2008-12-30 | 2014-06-24 | Omicron Electronics Gmbh | Device and method for determining partial discharges at an electrical component |
WO2015177419A1 (en) | 2014-05-20 | 2015-11-26 | Nexans | High-voltage dry apparatus provided with a continuous monitoring device |
Families Citing this family (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES2379831A1 (en) * | 2010-05-26 | 2012-05-04 | Universidad Politécnica de Madrid | METHOD FOR THE CONTINUOUS MONITORING AND DIAGNOSIS OF SOURCES OF PARTIAL DISCHARGES (PDs) IN HIGH-VOLTAGE CABLES DURING CONNECTION TO, AND OPERATION IN THE POWER GRID, AND PHYSICAL SYSTEM FOR CARRYING OUT SAME |
CN102508135A (en) * | 2011-11-23 | 2012-06-20 | 华南理工大学 | Cable oscillation wave local discharge measuring and positioning system based on cloud computing |
US9001941B2 (en) * | 2012-01-31 | 2015-04-07 | Analog Devices, Inc. | Method and apparatus to independently control front end gain and baseband gain |
CN102590619B (en) * | 2012-03-14 | 2014-01-08 | 国家电网公司 | Method for detecting time synchronization capacity of real-time measurement equipment based on timing variable |
DK2904413T3 (en) * | 2012-10-05 | 2017-04-10 | Prysmian Spa | Partial discharge detection and synchronization detection system |
CN103078402B (en) * | 2012-12-28 | 2015-01-07 | 中国电力科学研究院 | High-voltage cable partial-discharge quantity-of-state networking measurement time precise synchronizing method |
CN104849686B (en) * | 2015-04-27 | 2017-10-31 | 上海交通大学 | Partial discharge detector's performance evaluation system |
CN104932325B (en) * | 2015-04-30 | 2017-04-12 | 广东电网有限责任公司佛山供电局 | Synchronous voltage signal phase frequency check instrument based on cable partial discharge test |
US10254330B2 (en) * | 2015-08-26 | 2019-04-09 | Avo Multi-Amp Corporation | Partial discharge detection bandwidth expansion through input signal aliasing |
KR101787901B1 (en) * | 2016-06-14 | 2017-11-15 | 엘에스산전 주식회사 | Power equipment diagnostic apparatus |
CN106501695B (en) * | 2017-01-06 | 2019-10-08 | 云南电网有限责任公司电力科学研究院 | A kind of high-tension cable local discharge signal acquisition processing system and method |
CA3033769A1 (en) * | 2019-02-14 | 2020-08-14 | Daniel Pineau | Partial discharge detector and associated method |
KR102393662B1 (en) * | 2019-07-18 | 2022-05-02 | 한국전기연구원 | System and method for diagnosing partial discharge of electric power equipment, and a recording medium having computer readable program for executing the method |
CN112257640A (en) * | 2020-10-30 | 2021-01-22 | 国网上海市电力公司 | Pulse characteristic parameter extraction method based on Hibert transformation and information entropy |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5107447A (en) * | 1988-05-16 | 1992-04-21 | Hitachi, Ltd. | Abnormality diagnosing system and method for a high voltage power apparatus |
US6313640B1 (en) * | 1998-02-03 | 2001-11-06 | Abb Power T & D Company, Inc. | System and method for diagnosing and measuring partial discharge |
US20010040459A1 (en) * | 1999-01-28 | 2001-11-15 | Hitachi, Ltd. | Method of diagnosing partial discharge in gas-insulated apparatus and partial discharge diagnosing syatem for carrying out the same |
WO2005038475A1 (en) * | 2003-10-22 | 2005-04-28 | Fujikura Ltd. | Insulation degradation diagnosis apparatus |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3403227A (en) * | 1965-10-22 | 1968-09-24 | Page Comm Engineers Inc | Adaptive digital vocoder |
US3538505A (en) * | 1968-05-01 | 1970-11-03 | Fabritek Instr Inc | Waveform measuring system and method |
US4020286A (en) * | 1975-05-19 | 1977-04-26 | Metrosonics, Inc. | Signal analysis apparatus for amplitude statistics |
US5136652A (en) * | 1985-11-14 | 1992-08-04 | Ncr Corporation | Amplitude enhanced sampled clipped speech encoder and decoder |
JPH04204270A (en) * | 1990-11-30 | 1992-07-24 | Toshiba Corp | Partial-discharge detecting device for gas insulation switching device |
JP3187642B2 (en) * | 1994-02-25 | 2001-07-11 | 関西電力株式会社 | Electrical device abnormality detection method and rotating electrical machine abnormality detection device |
US6242922B1 (en) * | 1998-11-06 | 2001-06-05 | General Electric Company | Arc detection architecture based on correlation for circuit breakers |
KR100529377B1 (en) * | 2004-03-15 | 2005-11-17 | 한국전력공사 | Partial discharge monitoring system of high voltage rotating machine |
ITPR20060054A1 (en) * | 2006-06-13 | 2007-12-14 | Techimp S R L | INSTRUMENT AND PROCEDURE FOR DETECTION OF PARTIAL ELECTRIC DISCHARGES IN AN ELECTRIC SYSTEM |
ITPR20070061A1 (en) * | 2007-07-26 | 2009-01-27 | Techimp S P A | INSTRUMENT AND PROCEDURE FOR DETECTING PARTIAL ELECTRICAL DISCHARGES WHICH HAVE SITE IN AN ELECTRICAL EQUIPMENT |
ITPR20070058A1 (en) * | 2007-07-26 | 2009-01-27 | Techimp S P A | PROCEDURE AND APPARATUS FOR MONITORING AN ACTIVITY OF PARTIAL ELECTRIC DISCHARGES IN AN ELECTRICALLY POWERED EQUIPMENT WITH CONTINUOUS VOLTAGE |
-
2006
- 2006-06-13 IT IT000054A patent/ITPR20060054A1/en unknown
-
2007
- 2007-04-11 CN CN201410001520.4A patent/CN103809088A/en active Pending
- 2007-04-11 CN CNA2007800220989A patent/CN101467055A/en active Pending
- 2007-04-11 KR KR1020097000719A patent/KR101321561B1/en active IP Right Grant
- 2007-04-11 EP EP07735458A patent/EP2027478B1/en not_active Revoked
- 2007-04-11 ES ES07735458T patent/ES2391582T3/en active Active
- 2007-04-11 BR BRPI0712828-2A patent/BRPI0712828A2/en not_active Application Discontinuation
- 2007-04-11 WO PCT/IB2007/051293 patent/WO2007144789A2/en active Application Filing
- 2007-04-11 US US12/304,410 patent/US8055459B2/en active Active
- 2007-04-11 KR KR1020137018182A patent/KR101423753B1/en active IP Right Grant
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5107447A (en) * | 1988-05-16 | 1992-04-21 | Hitachi, Ltd. | Abnormality diagnosing system and method for a high voltage power apparatus |
US6313640B1 (en) * | 1998-02-03 | 2001-11-06 | Abb Power T & D Company, Inc. | System and method for diagnosing and measuring partial discharge |
US20010040459A1 (en) * | 1999-01-28 | 2001-11-15 | Hitachi, Ltd. | Method of diagnosing partial discharge in gas-insulated apparatus and partial discharge diagnosing syatem for carrying out the same |
WO2005038475A1 (en) * | 2003-10-22 | 2005-04-28 | Fujikura Ltd. | Insulation degradation diagnosis apparatus |
Non-Patent Citations (1)
Title |
---|
HOSHINO T ET AL: "Real-time PD identification in diagnosis of GIS using symmetric and asymmetric UHF sensors" IEEE/PES TRANSMISSION AND DISTRIBUTION CONFERENCE AND EXHIBITION 2002 : ASIA PACIFIC. YOKOHAMA, JAPAN, OCT. 6 - 10, 2002, IEEE/PES TRANSMISSION AND DISTRIBUTION CONFERENCE AND EXPOSITION, NEW YORK, NY : IEEE, US, vol. VOL. 1 F 3, 6 October 2002 (2002-10-06), pages 798-801, XP010630413 ISBN: 0-7803-7525-4 * |
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8055459B2 (en) * | 2006-06-13 | 2011-11-08 | Techimp Technologies S.R.L. | Instrument and method for measuring partial electrical discharges in an electrical system |
US8760171B2 (en) | 2008-12-30 | 2014-06-24 | Omicron Electronics Gmbh | Device and method for determining partial discharges at an electrical component |
US9400305B2 (en) | 2009-05-29 | 2016-07-26 | Techimp Hq S.R.L. | Instrument and method for detecting partial electric discharges in an electric apparatus |
WO2010136999A1 (en) | 2009-05-29 | 2010-12-02 | Techimp Technologies S.R.L. | Instrument and method for detecting partial electric discharges in an electric apparatus |
US20120095710A1 (en) * | 2009-05-29 | 2012-04-19 | Techimp Technologies S.R.L. | Instrument and method for detecting partial electric discharges in an electric apparatus |
CN102449492A (en) * | 2009-05-29 | 2012-05-09 | 特英普科技有限公司 | Instrument and method for detecting partial electric discharges in an electric apparatus |
WO2011051910A1 (en) | 2009-10-30 | 2011-05-05 | Techimp Technologies S.R.L. | Device and method for detecting and processing signals relating to partial electrical discharges |
US9037438B2 (en) | 2009-10-30 | 2015-05-19 | Techimp Hq S.R.L. | Device and method for detecting and processing signals relating to partial electrical discharges |
WO2011110984A1 (en) | 2010-03-10 | 2011-09-15 | Techimp Technologies S.R.L. | Instrument and method for detecting partial electrical discharges |
US8901941B2 (en) | 2010-03-10 | 2014-12-02 | Techimp Technologies S.R.L. | Instrument and method for detecting partial electrical discharges |
US8990035B2 (en) | 2010-03-10 | 2015-03-24 | Techimp Hq S.R.L. | Instrument and method for detecting partial electrical discharges |
WO2011110986A1 (en) | 2010-03-10 | 2011-09-15 | Techimp Technologies S.R.L. | Instrument and method for detecting partial electrical discharges |
EP2545388B2 (en) † | 2010-03-10 | 2022-11-16 | Techimp HQ S.R.L. | Instrument and method for detecting partial electrical discharges |
WO2014024060A1 (en) | 2012-08-06 | 2014-02-13 | Techimp Technologies S.R.L. | Device for monitoring an activity of partial discharges which occurs in an electrical apparatus |
WO2015177419A1 (en) | 2014-05-20 | 2015-11-26 | Nexans | High-voltage dry apparatus provided with a continuous monitoring device |
Also Published As
Publication number | Publication date |
---|---|
BRPI0712828A2 (en) | 2012-07-24 |
KR101321561B1 (en) | 2013-10-25 |
WO2007144789A3 (en) | 2008-02-21 |
EP2027478A2 (en) | 2009-02-25 |
CN101467055A (en) | 2009-06-24 |
KR20130087619A (en) | 2013-08-06 |
EP2027478B1 (en) | 2012-08-01 |
KR20090031727A (en) | 2009-03-27 |
CN103809088A (en) | 2014-05-21 |
ES2391582T3 (en) | 2012-11-28 |
KR101423753B1 (en) | 2014-08-13 |
US20090248327A1 (en) | 2009-10-01 |
US8055459B2 (en) | 2011-11-08 |
ITPR20060054A1 (en) | 2007-12-14 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US8055459B2 (en) | Instrument and method for measuring partial electrical discharges in an electrical system | |
CN100529766C (en) | Equivalent sampling device | |
US6374388B1 (en) | Equivalent time capture scheme for bit patterns within high data rate signals | |
EP2545388B1 (en) | Instrument and method for detecting partial electrical discharges | |
WO2015087284A1 (en) | Analyzing partial discharge in an electric power distribution system | |
JP2006329979A (en) | Measuring equipment, autocorrelation trigger generation method and generator | |
US20120271574A1 (en) | Real-Time and Off-Line Tools for Monitoring and Analysis of Power System Components | |
JP2020502522A (en) | Line fault signature analysis | |
EP2545389B1 (en) | Instrument and method for detecting partial electrical discharges | |
CN110988624B (en) | Detection method and system for intermittent partial discharge signal | |
US9400305B2 (en) | Instrument and method for detecting partial electric discharges in an electric apparatus | |
CN107037338A (en) | A kind of GIS oscillatory surges pressure test default kind identification method | |
US8792542B2 (en) | Method and device for improved detection and analysis of partial discharge activity in and around high voltage electrical equipment | |
US8818745B2 (en) | Monitoring and analysis of power system components | |
CN106019042A (en) | Method of identifying high voltage cable inner insulation defect type based on specific chromatograms | |
CN112285508B (en) | Positioning method for partial discharge of high-voltage power cable | |
CN118302679A (en) | Method and apparatus for signal pattern recognition | |
Moreno et al. | Test and Analysis of a Novel Segmentation Method Using Measurement Data |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 200780022098.9 Country of ref document: CN |
|
DPE1 | Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101) | ||
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 07735458 Country of ref document: EP Kind code of ref document: A2 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 12304410 Country of ref document: US |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2007735458 Country of ref document: EP |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 5135/KOLNP/2008 Country of ref document: IN |
|
NENP | Non-entry into the national phase |
Ref country code: RU |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1020097000719 Country of ref document: KR |
|
ENP | Entry into the national phase |
Ref document number: PI0712828 Country of ref document: BR Kind code of ref document: A2 Effective date: 20081212 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1020137018182 Country of ref document: KR |