WO2023156019A1

WO2023156019A1 - Method and device for monitoring a high-energy network infrastructure

Info

Publication number: WO2023156019A1
Application number: PCT/EP2022/054268
Authority: WO
Inventors: Biagio ZOCCOLILLO; Olivier BARTHE; Martin Heuschkel
Original assignee: Energie Network Services Ag; Emhc Ag
Priority date: 2022-02-21
Filing date: 2022-02-21
Publication date: 2023-08-24

Abstract

The invention relates to a method and device for monitoring a network infrastructure having a plurality of system components, wherein the method comprises: measuring a three-dimensional magnetic field on a system component in phase synchronicity with a main magnetic field induced by a useful current and generating a time-dependent signal that is proportional to the current; dividing the time-dependent signal into time units along a period of the system frequency and system phase position; adjusting the time-dependent signal by eliminating signal portions; transforming the time-dependent and adjusted signal into a frequency-dependent spectrum; reducing the frequency-dependent spectrum to a definable number of harmonics; comparing the reduced frequency-dependent spectrum with data, stored in a database, of change patterns; and outputting a notification if there are deviations of the detected spectrum of the monitored system component from change patterns.

Description

METHOD AND DEVICE FOR MONITORING A HIGH ENERGY NETWORK INFRASTRUCTURE

Technical field of the invention

The invention relates to a method and a device for monitoring a high-energy network infrastructure. According to the invention, faults in dielectrics, for example in insulators, surge arresters, switches, transformers, reactive current compensators, capacitors and other system components of a network infrastructure can generally be detected by analyzing small magnetic fields in the network infrastructure. This provides an opportunity to proactively coordinate the maintenance of the network infrastructure.

State of the art

In order to ensure a high level of stability of an electricity transmission network and thus secure use of the electricity network or network infrastructure that can be tailored to needs, despite increasing size and complexity, timely information is required. This information, accessible through fast and direct measurement of network conditions, can be used for rapid adjustment of network infrastructure and for proactive maintenance planning. Accordingly, there is a great need to be able to reliably localize faults in a high-energy network infrastructure.

Methods and devices for detecting and localizing fault events within an electricity transmission network are known. In general, such a method relies on measurements of parameters of the electricity transmission network at different points and on a system configured to receive and analyze the ascertainable data. It is known to analyze the frequency changes caused by an interference event after eliminating high-frequency components with regard to their sequence and reception pattern and thus to triangulate the type and location of the event. However, there is one for this Measurement of a complete frequency cycle is required and information is lost by eliminating the high frequencies.

Furthermore, a method is known which uses the magnetic fields emanating from the monitored high-voltage lines and a signal synchronized with the mains frequency emanating from the high-voltage lines for monitoring.

WO 2009037163 discloses a method and a device for measuring and/or calculating the magnitude and direction of the power flow in a power transmission line almost in real time. This includes the calculation of an active and a reactive power to determine a different power factor. Measurable power grid parameters such as shape, behavior, period and nominal frequency of magnetic field signals and voltage signals and higher and lower harmonic frequencies and their deviation relative to the expected power grid parameters are used.

The known methods and devices have the weakness of placing a large number of means outside the field but in the vicinity of the power lines and achieving a sufficient speed in the analysis.

The object of the present invention is to propose a method and a device to enable faults in and maintenance planning of a high-energy network infrastructure with little effort and, if possible, in real time.

Summary of the Invention

The present invention provides a method and apparatus for monitoring a high-energy network infrastructure.

The grid infrastructure for the secure supply of consumers with electrical energy has to be, despite strong fluctuations in some cases are kept stable and secure over the course of the day and year as production and consumption change. The network infrastructure includes high-voltage lines such as overhead lines and/or underground cables, always designed as a three-wire system, and support masts. The relevant system components of the grid infrastructure also include transformers, switches and secondary systems. Although overhead lines are exposed to environmental influences, they are advantageous compared to underground cables in terms of the ability to localize and rectify faults. Overhead pylons for high-voltage lines, also known as high-voltage pylons, are equipped to accommodate three conductor cables or an integral multiple thereof. Corresponding insulators are often hanging insulators, which are provided on high-voltage pylons designed as steel framework pylons.

A change in harmonic characteristics of dielectrics, such as insulators, of a transmission line can be measured using a parameter value detected by an electromagnetic sensor. In this context, it is of particular interest to filter out the portion of the harmonics which, according to one aspect of the invention, is possible in a narrow-band manner from an otherwise high-energy interference spectrum. Thus, a magnetic field that can be measured on a monitored system component can be set in phase relationship with another signal that is synchronized with the mains frequency. The signal values can be processed by transduction, for example filtered or cleaned up. The amounts and relative phase angles of the signals can be converted into digital signals, evaluated and stored. The digital signals can be analyzed and recorded, for example by means of a central processing unit. In addition to communication means for transmitting data, storage means for storing data can also be included. The superposition of a harmonic wave and the fundamental frequency shows a non-sinusoidal waveform. With the help of a Fourier transformation or other mathematical methods, a measured signal form can be broken down into a signal form of the fundamental wave and that of the harmonic wave. To determine harmonics or for signal analysis, a fast Fourier transformation is often used, among other things, in order to obtain a spectrogram as a representation of the composition of the signal from individual frequencies over time. In this case, FFT (Fast Fourier Transformation) is preferably used, or alternatively, for example, a PLL (Phase Locked Loop) method can be used. A spectrum can be calculated by means of a fast Fourier transformation, it being possible by means of PLL, for example, to track the starting point of the period in the time range under consideration. In addition, other suitable calculation methods such as digitally realized lock-in amplifiers and digital detectors as well as narrow-band filters can be used.

In reality, there are usually several overhead lines, so that a principle of superposition applies to the size of detectable magnetic field vectors. According to the invention it is possible to measure very weak currents in an environment of very strong current flows. Of particular interest is the measurement of leakage currents in a component structure of the network infrastructure, for example on the high-voltage pylon, in particular on arms of the high-voltage pylon. In principle, measurements at the base would also be conceivable, although these are less suitable due to the significantly more complex post-processing due to many more interference and external influences than at the mast arm. In this case, currents are assigned to their induced magnetic fields by spatial assignment or isolation, and this assignment preferably takes place in a narrow band. This is possible through a phase-synchronous measurement of the fundamental and harmonics of the system frequency.

To allocate power in power transmission lines of a high-energy network infrastructure to the induced magnetic fields, spatially and temporally defined measuring points are defined, at which magnetic field sensors are arranged. The values that can be recorded at the defined measuring point represent a superimposition of a large number of magnetic fields with different orientations and from different locations. The parameters that can be assigned to the magnetic fields, which can be recorded and measured at the defined measuring point, must therefore be evaluated in such a way that that these can be assigned to the original current flows of the individual components of the high-energy network infrastructure.

The parameters of a magnetic field generated by the electric currents transported in the transmission lines that can be detected at the defined measuring point can be a spatial orientation, a geometric position in the network infrastructure relative to the position of the measuring point, a time profile, a phase position relative to a reference frequency, an intensity and/or be a spectral composition.

In order to enable an exact and improved spatial assignment of the magnetic fields to their currents, a definable spatial orientation of electromagnetic sensors, for example magnetic field sensors, can be used.

In a further embodiment of the invention, at least one acceleration sensor is used to determine the position of the magnetic field sensors in space, in order to detect unwanted accelerations which can be caused, for example, by earthquakes, storms, sabotage and the like.

In general, magnetic field sensors are used to determine the strength and/or direction of an electromagnetic field, ie a magnetic field, at a location. A magnetic field sensor can be set up to measure changes in the flow of the magnetic field at defined time intervals or continuously. Magnetic field measurements may include peak, integral, shape, and/or frequency. In addition, an exact, known position in space can be assigned to each of the magnetic field sensors that can be arranged. In particular, the measurement data recorded and measured by the magnetic field sensors can be marked with a defined time code and/or a defined position information at the location of the measuring point and as an orientation in space. Based on this data, it is possible to create a model of the magnetic field in which the defined magnetic field sensor is placed. According to one embodiment of the invention, the measuring arrangement for measuring the magnetic field comprises at least one three-dimensional ultra-sensitive magnetic field sensor. For example, these are magneto-resistive sensors, flux gate sensors and/or Hall sensors and/or combinations of these magnetic field sensor technologies in order to use the measurable magnetic field with a resolution of a few picotesla and/or a sensitivity in the nanotesla range to detect the leakage current or leakage currents in a dielectric component, such as an insulator, of the network infrastructure. The magnetic field sensors mentioned are generally characterized by a strong dependency on the orientation of the magnetic field relative to the sensor and a strong dependency on the magnitude of the magnetic field. Accordingly, magnetic fields can be detected in all three spatial directions with one sensor unit. In this case, the 3D magnetic field sensor can comprise individual sensor elements arranged directly adjacent to one another, of which one sensor element each is used for detecting a magnetic field in one spatial direction, with this having its defined sensitivity direction. Accordingly, specific and possibly different 3D magnetic field sensors can be combined in one assembly depending on the sensitivity range. The existing magnetic field is thus recorded using its vectorial individual components. The magnetic field vector at the location of the sensor element can be reconstructed in an evaluation unit by vectorial addition. Corresponding sensor elements are characterized by a high sensitivity, which is specified differently in the three spatial axes, as well as the possibility of compensating for offsets and temperature by means of integrated electronics.

A magnetic field sensor designed as a three-dimensional magnetoresistive sensor and a magnetic field sensor designed as a fluxgate sensor is preferably used, which has a corresponding number of sensitive measuring surfaces. The sensitive measuring surfaces can be arranged approximately in the shape of a cross and form a kind of sensor array, so that a measurement of the three-dimensional magnetic field can be determined at the same location or at a common point. Measures such as shielding on the one hand and iron cores on the other, as well as a defined design of the magnetic field sensors and their technology, can make one of the axes more sensitive than the others Axles. Accordingly, magnetic sensitivities that are several powers of 10 higher can be achieved for one and/or two of the three measuring field components.

In a further embodiment of the invention, the at least one electromagnetic sensor is a coil probe and is set up for the high-resolution measurement of magnetic fields. Such a measuring arrangement for measuring a magnetic field or a magnetic field change uses planar or toroidal coils for detecting magnetic fields in a detection plane whose surface normal is aligned perpendicular or transverse to the magnetic field component to be determined. Magnetic field sensors designed as toroidal coils use the flux-conducting toroidal core to significantly increase the sensitivity in the detection plane compared to a planar coil. Depending on the signal frequency and whether an additional ferromagnetic core is used in the coil, magnetic field amplitudes can be determined over a wide range. Likewise, three mutually orthogonal elements, preferably with different measurement sensitivities, can be combined with one another in order to determine the magnetic field vector. For example, such an arrangement can additionally include magnetic field sensors of the type magnetoresistive sensor, fluxgate sensor and/or Hall sensor in each of the three spatial axes.

According to one embodiment of the invention, the analysis includes a correlation of the harmonic components filtered out with the state of dielectrics. This is based on the changing dielectric properties of the material, for example insulators, preferably silicone and its composite materials. Silicone-coated dielectrics are subject to a typical aging process. One of the consequences of this is that they have a spectrum that is characteristic of the aging condition when leakage current is flowing through them. Accordingly, the condition and/or an expected remaining service life of the dielectric can be inferred from the spectrum that can be determined, taking into account the conditions of use and taking into account parameters such as temperature, humidity, degree of contamination and other influencing factors. The method according to the invention comprises the following steps:

- Measuring a three-dimensional magnetic field on a system component in phase synchronism with a main magnetic field induced by a useful current and generating a time-dependent signal proportional to the current;

- Subdividing the time-dependent signal into time units along a period of the system frequency and system phase. Time units can be defined and can be 20 ms or 1/50 s, for example.

- Clean up the time-dependent signal by eliminating signal components. In the process, system parts are eliminated which are induced by the useful current and/or non-system components. These are induced, for example, by rail traffic, lightning, radio, WLAN and/or mobile phones. The non-system frequency components have no correlation to the system frequency of the components monitored using the method according to the invention and can simply be ignored.

- Transforming the time-dependent and adjusted signal into a frequency-dependent spectrum. The transformation can preferably take place by means of a Fourier transformation.

- Reduction of the determined spectrum to a determinable number of harmonics, for example 10 harmonics.

- Comparing the reduced frequency-dependent spectrum with data of change patterns stored in a database. Detectable changes can be based on aging or damage. The quality of the analysis increases with the available amount of data and/or by using artificial intelligence for a self-learning adaptation of the change patterns. Changes can be traced back to abruptly occurring or gradual changed states of a monitored system component, which can be displayed to the system operator. Events such as an unexpected change, as well as information relevant in this context, can be displayed to the operator of the network infrastructure as acoustic and/or visual warnings on suitable devices.

In a further embodiment, a galvanic measurement can also be used as a measurement method, in particular where the measurement of a magnetic field is not possible and at the same time a corresponding physical intervention in the system is not disruptive. A galvanic measurement involves de-energizing the system and arranging a measurement arrangement that measures the leakage current directly or via a current divider, e.g. a shunt. Leakage current is measured grounded to earth or zero potential.

In another aspect of the invention, this relates to a device for monitoring a network infrastructure with a large number of system components, which device comprises at least one electromagnetic sensor for measuring a three-dimensional magnetic field in at least one of the system components and for generating a time-dependent signal. Furthermore, means are provided for receiving the time-dependent signal and for analyzing this transformed and cleaned up. Changes can be determined from a comparison with stored data in connection with known change patterns.

For example, a 3D fluxgate sensor, a magnetoresistive sensor and/or a Hall sensor can be provided as an electromagnetic sensor in the vicinity of the system component to be monitored. Alternatively, the at least one electromagnetic sensor can also be electrically connected to the system component to be monitored if this is possible in the position.

According to one exemplary embodiment, the means include an algorithm, by means of which the signal values can be processed. For example, the signal values can be cleaned of interference components, converted into a Frequency-dependent spectrum transformed and / or reduced in terms of the frequency range under consideration. The data processed in this way can be compared with stored data, which can be known change patterns and/or data that can be adapted on the basis of a self-learning system.

Adjustments to the device and/or the method can be made based on practical experience.

Further details of the invention emerge from the following description of preferred embodiments, which are illustrated by way of example in the accompanying drawings. The further advantages of the present invention can be gathered from the description, as well as suggestions and suggestions as to how the subject of the invention can be modified or further developed within the scope of what is claimed.

Brief description of the drawings

Show it:

FIG. 1 shows a schematic representation of a measuring arrangement for measuring magnetic fields on a mast arm according to an embodiment of the invention;

FIG. 2 shows a schematic representation of a measuring arrangement for measuring magnetic fields on a mast arm according to a further embodiment of the invention;

FIG. 3 shows a schematic representation of a signal recorded by the measuring arrangement and a representation of the transformed signals. Preferred embodiments of the invention

FIG. 1 shows a schematic representation of a measuring arrangement 10 for measuring a magnetic field in a component of a network infrastructure 1 . In the embodiment shown, the network infrastructure 1 comprises at least one overhead line 2 which is arranged on one of the plurality of mast brackets 3 . According to the illustrated embodiment, a measuring arrangement 10, for example a 3D magnetic field sensor 12, is arranged close to the mast arm 3 for measuring the magnetic field. The 3D magnetic field sensor 12 is arranged in such a way that it is aligned orthogonally to a main magnetic field induced by the useful current. In particular, the 3D magnetic field sensor 12 is arranged close to the mast arm 3 .

An arrangement of the measuring arrangement 10 on the pylon arm 3 is advantageous compared to an arrangement at the base of an electricity pylon. Measurements at the base generally contain significantly more interference and extraneous influences, which have to be eliminated using complex methods in order to actually be able to serve as the basis for an interference analysis. Accordingly, despite a more complex arrangement of the measuring arrangement 10 on the mast arm 3, this is advantageous in order to enable a more precise localization of leakage currents that occur.

Measuring arrangement 10 comprising at least one 3D magnetic field sensor 12 is set up to measure leakage currents on dielectrics. The temporal signals that can be detected in this way, which are correspondingly cleaned and subjected to a transformation, serve as the basis for an analysis or a comparison with known change patterns in order to detect both spontaneously occurring and gradually changing states of the monitored dielectric component.

FIG. 2 shows a further embodiment in detail, with the measuring arrangement 10 being designed as a coil probe 14 for measuring the induced magnetic field. The coil probe 14 comprises an excitation coil, an induction coil and a magnetic core, the measured external magnetic field, the basic magnetization of the magnetic core varies, with an induction current depending on the varying basic magnetization at the induction coil can be tapped as a measurement signal. Compensation for undesired magnetic field entries at the measuring point(s) can be achieved with a further 3D magnetic field sensor 12 in which these further sensors can be positioned in the vicinity of the known source of interference and thus also referenced in a signal evaluation.

In FIG. 3, the data originating from the measuring arrangement 10 over time is shown schematically in a graph. Here, the first curve 20 traces the course of the useful current, which can be seen as a fundamental wave with a frequency of 50 Hz. The leakage current is represented by the second curve 22 and a third curve 24 represents the superimposition of the useful current and the leakage current. The curves shown are idealized and simplified for better understanding. The profile of the leakage current, i.e. the profile of the second curve 22, is relevant for analyzing the status of the monitored system component. Of particular importance here are the first harmonics, i.e. integer multiples of the fundamental frequency. In the example shown, this is three times the fundamental frequency. By means of a Fourier transformation, for example, a frequency-dependent representation of the useful current 20 and the leakage current 22 can also be generated from the course of the third curve 24 or the current course over time and knowledge of the fundamental wave, as shown in FIG.

Claims

patent claims

1 . Method for monitoring a network infrastructure with a large number of system components, comprising

- dividing the time-dependent signal into time units along a period of the system frequency and system phase;

- Clean up the time-dependent signal by eliminating signal components;

- Transforming the time-dependent and adjusted signal into a frequency-dependent spectrum;

- Reduction of the frequency dependent spectrum to a definable number of harmonics;

- comparing the reduced frequency dependent spectrum with change pattern data stored in a database; and

- Outputting a message in the event of deviations in the determined spectrum of the monitored system component from change patterns.

2. The method as claimed in claim 1, characterized in that the system parts induced by the useful current and/or non-system components are eliminated during the cleaning of the time-dependent signal.

3. The method according to claim 1 or 2, characterized in that the measurement of the three-dimensional magnetic field is carried out continuously by means of at least one measuring arrangement.

4. The method according to claim 3, characterized in that the measuring arrangement is arranged in the area of a mast arm of the network infrastructure.

5. The method according to any one of the preceding claims, characterized in that the time-dependent signal is divided into time units of approximately 20 ms.

6. The method according to any one of the preceding claims, characterized in that the definable number of harmonics is 10.

7. The method according to any one of the preceding claims, characterized in that identifiable data is transmitted to a storage unit and stored.

8. The method as claimed in claim 7, characterized in that the data which can be determined are transmitted in encrypted form to an external storage unit and stored.

9. The method according to any one of the preceding claims, characterized in that artificial intelligence is used for the analysis.

10. Device for monitoring a network infrastructure with a large number of system components according to a method according to any one of claims 1 to 9, comprising

- at least one electromagnetic sensor for measuring the three-dimensional magnetic field in at least one of the system components and generating a time-dependent signal,

- means for receiving the time-dependent signal and analyzing a transformed and cleaned time-dependent signal in order to determine changes in change patterns by comparison with data stored in a memory unit.

11 . Device according to Claim 10, characterized in that the electromagnetic sensor is a 3D Hall sensor.

12. The device according to claim 11, characterized in that the electromagnetic sensor comprises a coil probe.

13. Device according to one of the preceding claims 10 to

12, characterized in that the electromagnetic sensor, as a three-dimensional magnetic field sensor, has different sensitivities in the x, y, z spatial directions.

14. Device according to one of claims 10 to 13, characterized in that the electromagnetic sensor is galvanically connected to the system component to be monitored.

15. Device according to one of claims 10 to 14, characterized in that the means comprise an algorithm.

16. Device according to one of claims 10 to 15, characterized in that an acceleration sensor is provided for determining the position of the electromagnetic sensor.