JP7833190B2 - A method for detecting electric arcs generated between railway overhead lines and railway traction equipment, and a corresponding detection device. - Google Patents

Description

This specification relates to a method for detecting an arc occurring between a railway overhead line carrying a DC voltage and a pantograph of a railway traction device that collects current absorbed or injected by the railway traction device, and to a corresponding detection arrangement.

One or more embodiments may be applied to applications for collecting energy consumption-related data and transmitting it to a ground data collection system.

In most electric railway systems, power is transmitted from the power source to the traction device (locomotive or electric train) via sliding contacts between the overhead line (OHL) and the pantograph. The pantograph is a servo-operated current collector mounted on the roof of the train, controlling the force applied to the contact line by the contact strip. Because a large amount of power (up to approximately 8 MW) is transmitted from the OHL to the pantograph's carbon blades through a contact area of a few millimeters square, the current collector is one of the most important components of a railway power system.

By accurately analyzing the voltage and current detected by the pantograph, which collects the current absorbed by railway vehicles such as locomotives and electric locomotives, interesting information about the functional status of both the supply system and the vehicle can be obtained. Methods for detecting and reliably cataloging electrical events occurring in the pantograph can be used for predictive maintenance. One such event is the arc discharge phenomenon that occurs when the pantograph, which collects the current absorbed and injected by the locomotive, becomes detached from the overhead line (OHCL). The causes of separation between the two electrodes of the sliding contact can be summarized as track irregularities, catenary irregularities, high speeds, and weather conditions (snow, ice, frost). An increase in the number of arc events accelerates the deterioration of the current collector plate, leading to more arc events, potentially resulting in reduced power quality and accidents.

Therefore, counting arc discharges is desirable to monitor the condition of the pantograph and overhead lines. By combining such tools with data acquisition systems and widely disseminating them to all vehicles, it is possible to contribute to predictive maintenance of equipment involved in slip contact.

In particular, if all locomotives are equipped with devices to detect arc events and transmit the number of arc events to a ground data collection system in the future, predictive maintenance of contact quality between the pantograph and the overhead line (OHL) will be possible. Furthermore, in the future, all locomotives operating throughout Europe will be required to collect energy consumption data and transmit it to a ground data collection system. This obligation is imposed by the Technical Specification for Interoperability (TSI).

In the current system, the condition of the pantograph shoe (the element that contacts the OHCL) is monitored using a video system registration. However, this requires the installation of a video camera, and it is difficult to identify arc events from the acquired images.

Based on the above explanation, there is a perceived need for solutions to overcome one or more of the shortcomings outlined earlier.

According to one or more embodiments, such an objective is achieved through a method having features specifically defined in subsequent claims. The embodiments further relate to relevant detection arrangements.

The claims are an integral part of the technical teachings provided herein.

As stated above, this disclosure provides a solution for a method for detecting an arc occurring between a railway overhead line carrying a DC voltage and the pantograph of a railway traction device that collects current absorbed or injected by the railway traction device.
The aforementioned pantograph has an input low-pass filter,
The aforementioned input low-pass filter operates at a predetermined natural frequency,
At that input section,
The voltage between the pantograph, particularly the pantograph shoe and the reference node,
The current absorbed or injected by the aforementioned railway traction device is received,
The output section has a step of supplying the filtered voltage to the railway traction device,
The aforementioned method,
The steps include measuring the voltage between the pantograph and the reference node, and the current absorbed or injected by the railway traction device, and obtaining the measured voltage and measured current, respectively.
The steps include extracting an extracted voltage signal from the measured voltage, having a spectral portion divided around a predetermined detection frequency,
The steps include extracting an extracted current signal having a spectral portion delimited to the vicinity of a predetermined natural frequency from the measured current absorbed or injected into the locomotive,
A step of comparing the amplitude of the extracted voltage signal having a delimited spectral portion and the amplitude of the extracted current signal having a delimited spectral portion with their respective thresholds,
The comparison operation includes a step of checking whether the amplitude of the extracted voltage signal having a delimited spectral portion and the amplitude of the extracted current signal having a delimited spectral portion are both above their respective thresholds, and if the result of the check is positive, signaling for arc detection.

In a modified embodiment, extracting an extracted voltage signal having a spectral portion delimited near a predetermined detection frequency from the measured voltage includes performing analog Butterworth filtering or special resonant filtering near the predetermined detection frequency, and extracting an extracted current signal having a spectral portion delimited near a predetermined natural frequency from the measured current absorbed or injected by the locomotive includes performing analog passband Butterworth filtering, particularly of the second order, centered on the natural frequency of the input low-pass filter.
The comparison operation includes comparing the extracted voltage and the extracted current using their respective threshold comparators.

In a modified embodiment, the detection frequency is in the range of 1 kHz to 3 kHz, and in particular, the bandwidth of the analog Butterworth filtering is 143 Hz.

In a modified embodiment, the natural frequency ranges from 15 Hz to 30 Hz, and the bandwidth of the analog passband Butterworth filtering is, in particular, 11.2 Hz.

In a modified embodiment, the comparison operation includes delaying the output of the comparison of the extracted voltage portion.

In the modified embodiment, measuring the voltage is
This includes analog pre-filtering the measured voltage using an analog filter having a resonant frequency at the detection frequency, and digitally acquiring the analog-filtered voltage.
Measuring the current includes digitally acquiring the measured current in synchronization with acquiring the analog-filtered voltage.
Extracting an extracted voltage signal having a segmented spectral portion near a predetermined detection frequency from the measured voltage includes performing a fast Fourier transform on the measured voltage, particularly the analog-filtered voltage, and extracting a tone corresponding to the detection frequency.
Extracting an extracted current signal having spectral portions delimited around a predetermined natural frequency from the measured current absorbed or injected by the locomotive includes performing a fast Fourier transform on the measured current and extracting a tone corresponding to the natural frequency.

This includes comparing the voltage tone and the current tone with their respective single thresholds.

In a modified embodiment, the detection frequency of the analog pre-filtering is in the range of 1 kHz to 2 kHz.

In a modified embodiment, the Fast Fourier Transform of the measured voltage is performed with an analysis time in the range of 4 ms to 10 ms, and the Fast Fourier Transform of the measured current is performed with an analysis time in the range of 100 ms to 300 ms.

This disclosure also provides a solution relating to an apparatus for detecting arcs occurring between a railway overhead line carrying a DC voltage and the pantograph of a railway traction device that collects current absorbed or injected by the railway traction device.
The pantograph is equipped with an input low-pass filter that operates at a predetermined natural frequency.
At its input, it receives the voltage between the pantograph, particularly the pantograph shoe, and the reference node, and the current absorbed or injected by the railway traction device.
At its output, the filtered voltage is supplied to the railway traction device.
The device comprises a sensor module configured to measure the voltage between the pantograph and the reference node, and the current absorbed or injected by the railway traction device, and to obtain a measured voltage and a measured current, respectively.
The apparatus is configured to perform the steps of the method according to any of the embodiments described above.

The claims are an integral part of the technical teachings provided herein with reference to embodiments.

One or more embodiments are described, only as non-limiting examples, with reference to the attached figures.

Figure 1 is a schematic diagram providing a circuit description for arc events. Figure 2A is a time-lapse diagram showing the voltage and current behavior in a pantograph when an arc event is present. Figure 2B is an enlarged time diagram of the figure in Figure 2A. Figure 3 is a flowchart illustrating a general embodiment of the method described herein. Figure 4 is a schematic diagram of an arrangement for implementing the first embodiment of the method described herein. Figure 5 is a time diagram of the voltage quantity in the embodiment shown in Figure 4. Figure 6 is a time diagram of the current flow in the embodiment shown in Figure 4. Figure 7 is a time diagram of the voltage and current quantities in the embodiment shown in Figure 4. Figure 8 is a schematic diagram of an arrangement that implements the second embodiment of the method described herein. Figure 9 is a time diagram of the voltage quantity in the embodiment shown in Figure 8. Figure 10 is a time diagram of the current flow in the embodiment shown in Figure 8. Figure 11 is a time diagram of the voltage and current quantities in the embodiment shown in Figure 8.

The following description illustrates one or more specific details for the purpose of providing a deeper understanding of the embodiments described herein. Embodiments can be obtained without one or more specific details, or by using other methods, components, materials, etc. In other cases, known structures, materials, or operations are not illustrated or described in detail so as not to obscure specific aspects of the embodiments.

References to “one embodiment” or “one embodiment” within the framework of this specification are intended to indicate that a particular configuration, structure, or characteristic described in relation to an embodiment is configured in at least one embodiment. Therefore, expressions such as “in one embodiment” or “in one embodiment” that may appear in one or more places in this specification do not necessarily refer to the same single embodiment.

Furthermore, specific conformations, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

The references used herein are provided solely for convenience and therefore do not define the scope of protection or the scope of the embodiments.

Through the figures accompanying this specification, similar parts or elements are indicated by the same reference/number, and corresponding descriptions are not repeated for the sake of brevity.

The drawings are simplified and not to an accurate scale.

When separation occurs between the pantograph shoe and the overhead wire in the presence of a current flux, an electric arc is generated between the two electrodes of the sliding contact. While the physical description of an electric arc is complex, such an event can be easily described in a circuit model as an arbitrary voltage generator that provides an arbitrary pulse voltage waveform between the pantograph shoe and the overhead power line. A more detailed explanation can be found in the publication by G. Crotti et al., "Pantograph-to-OHL Arc: Conducted Effects in DC Railway Supply System," IEEE Transactions on Instrumentation and Measurement, Vol. 68, No. 10, pp. 3861-3870, October 2019.

Figure 1 is a schematic diagram providing a simple circuit description of an arc event occurring between absorption (positive) or current generation (negative) in a traction device, the latter of which can occur during the braking phase.

Therefore, Figure 1 shows a traction device 11, such as a locomotive, coupled to an overhead wire 12 that carries a DC supply voltage V _line supplied from an electrical supply system 13 by a pantograph 11a.

Due to its nature, the pantograph 11a is normally in contact with the overhead wire 12 which receives a DC supply voltage V _line . However, the voltage generator indicates the formation of an arc A between the overhead wire 12 and the pantograph 14, which has an arc voltage V _arc for one of the reasons mentioned above, and _Ip indicates the current flowing between the overhead wire 12 and the pantograph 11a.

In Figure 1, this is represented by an equivalent circuit of the coupling between the overhead wire 12 and the pantograph 11a, with the input filter 15 representing the input stage of the pantograph 14. As shown in the figure, the DC power supply voltage V _line is coupled to a terminal separated from the input terminal of the input filter 15 by an equivalent voltage generator representing the arc voltage V _arc . Therefore, the pantograph voltage V _p , which is the input voltage of the input filter 15, becomes V _line - V _arc , which corresponds to the DC power supply voltage V _line when there is no arc. The pantograph current I _p at the input node of the filter 15 is the current absorbed or injected into the overhead wire 12.

As shown in Figure 1, the pantograph voltage _Vp is formed between the pantograph 11a and a reference node, for example, an earth reference. Typically, the reference node is at zero voltage or a lower potential relative to the pantograph voltage _Vp or the DC supply voltage V _line . In embodiments, the reference node can be represented by a rail.

The input filter 15 is the low-pass input stage filter of the traction device 11, i.e., the locomotive, and is commonly found in DC locomotives. This filter plays an important role in understanding the electrical conduction effect caused by arcing. In Figure 1, it is diagrammed as an LC filter with a series inductor Lif and an output capacitor _Cif arranged in parallel. A filtered DC voltage V _dsf is formed at the terminals of the series inductor _Lif and the output capacitor Cif, which is the reference node, to supply to the electric motor of the traction device 12. As shown in Figure 1, the filtered DC voltage V _dsf is therefore also referred to as the pantograph voltage V _p , with respect to a reference node, for example, a ground reference. More generally, all potentials in the input filter 15, including the input node on which the pantograph voltage V _p is formed, are referred to as such a reference node, which may be a ground reference as described above, or represented by a rail in an embodiment. The rail does not necessarily have to be at zero voltage, but it does need to be at a low potential relative to the nodes of V _line , V _p , and V _dsf .

Figure 2A is a time diagram showing the behavior of voltage _Vp and current _Ip in the pantograph when arc event A is detected while locomotive 11 is absorbing current.

Figure 2B is a time-domain enlarged view of arc A in Figure 2A, showing the same electric quantity.

Electric arc A induces a voltage dip in the pantograph voltage _Vp when the traction device 11 is absorbing current, and an undulation when the traction device 11 is injecting current into the overhead line 12. Such rapid fluctuations induce oscillations in the secondary low-pass filter 15, which are reflected in the pantograph current _Ip .

Waveforms like the one shown in Figure 2A are described, for example, in Crotti, G.; Giordano, D.; Signorino, D.; Femine, A. Delle; Gallo, D.; Landi, C.; Luiso, M.; Biancucci, A.; Donadio, L.: "Monitoring Energy and Power Quality On Board Train." [Proceedings of 2019 IEEE 10th International Workshop on Applied Measurements for Power Systems (AMPS), Aachen (Germany), September 25-27, 2019.]

The solution described here utilizes the conduction effect caused by the arc, and generally, as shown in the flowchart of Figure 3 illustrating Embodiment 100 of the method, the pantograph voltage _Vp between the pantograph 11a and the reference node and the current _Ip absorbed or injected by the railway traction device 11 are measured, and the measured voltage _Vp,out and the measured current _Ip,out are obtained, respectively (step 110).
From the measured voltage V _{p, ou} t, an extracted voltage signal having a spectral portion V _bp delimited around a predetermined detection frequency f _det is extracted, i.e., a signal having a spectrum over a limited frequency range or band around a given detection frequency f _det , such as after bandpass filtering (step 120).
From the measured current I _{p, out} absorbed or injected by the locomotive, an extracted current signal having a delimited spectral portion I _bp around a predetermined natural frequency f _N of the input filter is extracted (step 130).
The amplitude of the extracted voltage signal having a delimited spectral portion V _bp and the amplitude of the extracted current signal having a delimited spectral portion I _bp are compared with their respective thresholds, the voltage threshold t _hv or the current threshold t _hv (step 140).
The comparison operation 140 verifies whether both the amplitude of the extracted voltage signal having a delimited spectral portion V _bp and the amplitude of the extracted current signal having a delimited spectral portion I _bp exceed their respective thresholds t _hv and t _hv (step 150).
If the threshold is exceeded, the detection AD of arc A is notified by a signal (step 160).

Referring to Figure 4, a detection configuration 200 is shown, representing a first embodiment of the method described here, which is more analog-oriented.

As schematically shown in Figure 4, step 110, which measures the pantograph voltage _Vp between the pantograph 11a and the reference node and the current _Ip absorbed or injected by the railway traction device 11 to obtain the measured voltage _Vp,out and the measured current _Ip,out respectively, is carried out by a composite current-voltage converter 11b. Preferably, such a composite current-voltage converter 11b operates over a wide bandwidth or equal frequency range, for example, to match the bandwidth of the downstream filters in the measurement chain shown below with reference to Figure 4, e.g., filters 220, 230. The sensor module corresponding to the converter 11b may also be embodied by separate voltage and current sensors.

Step 120, which extracts an extracted voltage signal V _bp having a spectral portion Vfilt delimited around a predetermined detection frequency f _det from such a measured voltage V _{p, out} , is embodied by filtering with an arbitrary, i.e., predetermined, passband second-order Butterworth filter 220 centered on the detection frequency f _det . The value of the detection frequency f _det in the embodiment can be selected in the range of 1 kHz to 3 kHz, and the bandwidth may be, for example, 143 Hz. This is an exemplary value, and different bandwidth values are possible, selected to balance the need for a sufficiently narrow bandwidth to enhance the peak with the increased cost of the circuit associated with such a narrow bandwidth.

In this embodiment, the extracted voltage signal, from which the spectral portion V _bp has been separated, is represented by the filtered analog voltage V _filt .

Step 130, which extracts an extracted current signal having a delimited spectral portion I _bp near a predetermined natural frequency f _N of the input filter from the measured current I _{p, out} absorbed or injected by the locomotive, is embodied by filtering with a passband second-order Butterworth filter 230 centered on the natural frequency f _N of the low-pass filter 15 of the input stage of the locomotive 11. The value of the natural frequency f _N depends on the resonant frequency of the input filter stage 15 of the locomotive, for example, the resonant frequency of the LC resonant circuit forming the passband second-order Butterworth filter 230. In this embodiment, the value of the natural frequency f _N can be selected in the range of 15 Hz to 30 Hz, and the bandwidth may be, for example, 11.2 Hz. The same considerations regarding the bandwidth value of the filter 220 also apply here. The extracted current signal having a delimited spectral portion I _bp is in this case embodied by the filtered current I _filt .

To compare the amplitude of the extracted voltage signal having a delimited spectral portion V _filt with the amplitude of the extracted current signal having a delimited spectral portion I _filt , respectively, at thresholds t _hv and t _hi , the filtered signals V _filt and I _filt are then processed by threshold comparators 240v and 240i, respectively, operating between positive and negative thresholds, +t _hv and -t _hv and +t _hi and -t _hi , respectively. If the filtered signals V _filt and I _filt are higher than the thresholds, the output signals t _{hv_out} and t _{hi_out} of the threshold comparators 240v and _240i are logical 1 for voltage and thi for current, respectively; otherwise, they are logical 0. The range of variation of the thresholds t _hv and t _hi is summarized in Table 1 below.

The output signal t _{hv_out} of the voltage comparator 240V is delayed in the delay block of the time delay unit 245, with delay D being 5ms in the illustrated example, and this delay provides the delayed output signal t _{hv_out_D} . The value of delay D is selected to compensate for the different time delays introduced by filters 220 and 230.

The output signals t _{hv_out_D} and t _{hi_out} from comparators 240v and 240i are sent to the AND logic gate 250 which implements verification 150 if the comparison operation 140 indicates that the amplitude of the extracted voltage signal with a delimited spectral portion V _filt and the amplitude of the extracted current signal with a delimited spectral portion V _filt both exceed their respective thresholds t _hv and t _hi .

The output signal of the AND logic gate 250 is flag AD, which is equal to 1, only if both output signals t _{hv_out} and t _{hi_out} are 1, i.e., they are above their respective thresholds t _hv and t _hi . This represents a positive or affirmative answer to verification step 150, and therefore arc detection is signaled in step 160. Otherwise, flag AD is zero, meaning no arc occurs if either output signal t _{hv_out} or t _{hi_out} is zero, i.e., below their respective thresholds t _hv and t _hi .

Figure 5 shows the measured voltage V _p,out , the filtering voltage V _filt , and the delayed output signal t _{hv_out_D} as functions of time t. The delay D of the delayed output signal t _{hv_out_D} is also shown relative to the oscillation before the threshold was exceeded. Such a delay D, of course, also exists for the next oscillation determined by arc A.

Figure 6 shows the measured current I _p,out , the filtering current I _filt , and the current output signal t _{hi_out} as functions of time t.

Figure 7 shows the measured voltage V _p,out and measured current I _p,out t superimposed on the same graph as functions of time t, with the resulting flag AD displayed. When flag AD becomes 1, an arc is detected.

Referring to Figure 8, a second embodiment of the method described here is shown, which is more digitally oriented.

As schematically shown in Figure 8, step 110, which involves measuring the pantograph voltage Vp between the pantograph 11a and the reference node and the current _Ip absorbed or injected by the railway traction device 11, and obtaining the measured voltage _Vp,out and the measured current _Ip,out respectively, is performed by a composite current-voltage converter 11b.

With respect to the measured voltage V _p,out , however, pre-filtering is also performed by analog filter 312, which is essentially a low-pass band filter, before step 120. Since the frequency response of this filter is flat at low frequencies and resonates at a predetermined detection frequency f _det (preferably in the range of [1 ÷ 2] kHz in this embodiment), only fast transients utilize the filter. The filter response of filter 312 to voltage for an actual arc event is reported in Figure 9, which shows a time diagram of the measured voltage V _p,out and amplitude V _pf @ f _det at the detection frequency f _det , in addition to the output t _{hv_out} of comparator _340v , which will be described better below. Thus, the voltage measurement step 110 is substantially analog pre-filtering of the measured voltage by analog filter 312 having a resonant frequency at the detection frequency, followed by digital acquisition of the analog filtered voltage V _pf by analog-to-digital voltage conversion module 314v, which generates a digital measured voltage V _p,d .

Furthermore, each analog-to-digital current conversion module 314i acquires the measured current I _p,out in synchronization with the voltage measurement signal and generates a digital measured current I _p,d .

Next, the digitally measured voltages V _p,d are subjected to a step in which a Fast Fourier Transform (FFT) is applied in an FFT block 320 for detecting the resonant frequency f _det of the upstream special filter 312 to extract an extracted voltage signal having a segmented spectral portion V _bp (in this case, tone VT) around a predetermined detection frequency f _det .

Similarly, the digitally measured currents I _p,d are subjected to an FFT in the FFT block 330 to detect the natural frequency f _N of the low-pass filter 15 in the input stage of the locomotive 11, as shown in Figure 11, and the current tone IT _t is extracted as the extracted portion.

The tone signals VT and IT are then compared to their respective thresholds t _hv and t _hi in the respective threshold comparators 340v and 340i. If the amplitude of tone signals VT and IT is higher than the threshold, t _{hv is 1} for the voltage signal and t _hi is 1 for the current signal. The output signals t _{hv_out} and t _{hi_out} of the respective comparators 340v and 340i are 1, otherwise they are 0. Figure 10 shows the time function of the measured current and tone signal IT at 15 Hz, along with the output t _{hi_out} of the current comparator 340i.

In this case, the output signals t _{hv_out} and t _{hi_out} from comparators 340v and 340i are sent to an AND logic gate 250 that specifically indicates verification 150 if the comparison operation 140 shows that the amplitudes of both the extracted voltage spectrum portion, in this case voltage tone VT, and the extracted current spectrum portion, in this case current tone IT, are above their respective thresholds t _hv and t _hi .

The output signal of the AND logic gate 250 is flag AD, which is equal to 1, only if both output signals t _{hv_out} and t _{hi_out} are 1, i.e., above their respective thresholds t _hv and t _hi . This represents a positive or affirmative answer to verification step 150, and therefore, arc detection is signaled in step 160. Otherwise, flag _AD is zero, meaning no arc occurs, as shown in Figure 11, where the measured voltage V _{p ,out} and _measured current I _p,out are superimposed on the same graph as a function of time t, and _the resulting flag AD is zero. When flag AD becomes 1, an arc is detected.

In this digital approach, the selected time interval for calculating the FFT transform in blocks 340v and 340i may be relevant to the detection of the studied tone. Since the operating conditions are usually far from a steady state, the time interval for the FFT calculation should be selected as small as possible to achieve a good approximation of the steady state. In addition, good spectral resolution is required, and therefore, sufficient analysis time is necessary to detect the tone. For this reason, an analysis time of [4–10] ms is preferred for detecting the resonant frequency of the upstream special filter, and [100–300] ms is preferred for detecting the natural frequency of the locomotive input stage low-pass filter.

The selection of thresholds applied to filtered voltage and current signals is clearly related to the type of railway system in which the electric arc detection device operates. These values are summarized in Table 2 below.

This solution allows for counting arc events to monitor the status of both the pantograph and the overhead connecting wires, without requiring any additional equipment to be installed on the locomotive roof beyond the already installed voltage/current converter.

This will enable widespread implementation of this solution in all locomotives involved in data collection systems, resulting in a valuable contribution to predictive maintenance of devices related to sliding contact, particularly the predictive maintenance of the quality of contact between the pantograph and the OHL.

Furthermore, the solution described here can collect energy consumption data and transmit it to a ground data collection system, such as those defined in the Interoperability Technical Specification (TSI). A communication system between the locomotive and the ground, positioned for energy billing, can be used to collect arc events from each locomotive. A suitable algorithm for managing such bug data can be used to identify potential problems with the pantograph or overhead contact loop (OHCL). In fact, if all locomotives running on a certain section detect an unusually high number of arc events, the problem is most likely due to the OHCL. Conversely, if a locomotive records an unusually high number of events on several sections, it suggests the problem is related to the pantograph.

It will be understood that the various individual implementation options illustrated through the figures attached to this specification are not necessarily intended to be adopted in the same combinations illustrated in the figures. Therefore, one or more embodiments may employ these (or otherwise optional) options individually and/or in different combinations with respect to the combinations illustrated in the attached figures.

Without impairing the underlying principles, details and embodiments may change significantly with respect to those described only as examples, without departing from the scope of protection. The scope of protection is defined by the appended claims.

Claims (10)

A method for detecting an arc (A, V arc) occurring between a railway overhead line (12) carrying a DC voltage (V _line ) and a pantograph (11a) of a railway traction device (11) that collects a current (I _p ) absorbed or injected by the railway _traction device (11),
The pantograph (11a) has an input low-pass filter,
The aforementioned input low-pass filter is
It operates at a predetermined natural frequency (f _N ),
At the input section of the input low-pass filter, the voltage ( _Vp ) between the pantograph shoe of the pantograph (11a) and the reference node and the current ( _Ip ) absorbed or injected by the railway traction device (11) are received, and
At the input section of the aforementioned low-pass filter, the filtered voltage (V _dsf ) is supplied to the railway traction device (11).
The above method further,
Step (110) of measuring the voltage ( _Vp ) between the pantograph shoe and the reference node and the current (Ip) absorbed or injected by the railway traction device (11), and obtaining the measured voltage ( _{Vp, out} ) and the measured current ( _{Ip, out} ), respectively.
Steps (120; 220; 320) include extracting an extracted voltage signal (V _bp ; V _filt ; VT) having a spectral portion delimited around a predetermined detection frequency (f _det ) from the measured voltage (Vp, out),
Steps (130; 230; 330) include extracting an extracted current signal (I _bp ; I _filt; IT) having a spectral portion delimited around a given natural frequency (f _N ) from the measured current (I _{p, out} ) absorbed or injected by the railway traction device,
A step (140; 240v, 240i; 340v, 340i) of comparing the amplitude of the extracted voltage signal (V _bp ; V _filt ; VT) having a delimited spectral portion with the amplitude of the extracted current signal (I _bp ; I _filt ; IT) having a delimited spectral portion with their respective thresholds ( _thv , _thi ),
A method comprising the steps of verifying whether the comparison step (140) indicates that both the amplitude of the extracted voltage signal (V _bp ; V _filt ; VT) having the delimited spectral portion and the amplitude of the extracted current signal (I _bp ; I _filt ; IT) having the delimited spectral portion are greater than or equal to their respective thresholds (th _hv , th _hi ) (steps 150; 250), and if the verification result is positive, emitting a signal indicating the detection of an arc (A) (step 160). The method according to claim 1,
Steps (120; 220; 320) of extracting an extracted voltage signal (V _bp ; V _filt ; VT) having a spectral portion delimited around a predetermined detection frequency (f _det ) from the measured voltage (V _{p, out} ) include steps (220) of performing analog Butterworth filtering or resonant filtering around the predetermined detection frequency (f _det ),
Steps (130; 230; 330) of extracting an extracted current signal (I _bp ; I _filt ; IT) having a spectral portion delimited around a given natural frequency (f _N ) from the measured current (Ip, out) absorbed or injected by the railway traction device include a step (320) of performing analog passband Butterworth filtering centered on the natural frequency (f _N ) of the input low-pass filter (15),
A method wherein the comparison step (140; 240V, 240I; 340V, 340I) includes a step (240V, 240I) of comparing the extracted voltage (V _filt ) and the extracted current (I _filt ) using their respective threshold comparators. The method according to claim 2,
The predetermined detection frequency (f _det ) is in the range of 1 kHz to 3 kHz, and the bandwidth of the analog Butterworth filtering (220) is 143 Hz, in a method. The method according to claim 2,
The aforementioned natural frequency (f _N ) is in the range of 15 Hz to 30 Hz kHz.
The bandwidth of the aforementioned analog bandpass Butterworth filtering is 11.2 Hz , according to the method. The method according to claim 2,
The method comprising the comparison step (140) including delaying the output of the comparison of the extracted voltage portions (245). The method according to claim 1,
The step of measuring the voltage (110) includes pre-filtering the measured voltage (V _{p, out} ) with an analog filter having a resonant frequency at a predetermined detection frequency (f _det ) to obtain an analog filtered voltage (V _pf ), and then digitally acquiring the analog filtered voltage (V _pf ) (314v).
The step of measuring the current (110) includes digitally acquiring the measured current (I _{p, out} ) in synchronization with the acquisition of the analog filtered voltage (V _pf ) (314i),
Steps (120; 220; 320) of extracting an extracted voltage signal (V _bp ; V _filt ; VT) having a spectral portion delimited around a predetermined detection frequency (f _det ) from the measured voltage (V _{p, out} ) include performing a fast Fourier transform (320) of the analog filtering voltage (V _pf ) to extract a voltage spectral portion (VT) corresponding to the predetermined detection frequency (f _det ) , wherein the voltage spectral portion (VT) corresponds to an extracted voltage signal having a delimited spectral portion near the predetermined detection frequency (f _det ).
Steps (130; 230; 330) of extracting an extracted current signal (I bp; I _filt ; IT) having a spectral portion delimited around a predetermined natural frequency (f _N ) from the measured current (I _{p , out} ) absorbed or injected by the railway traction device include performing a fast Fourier transform of the measured current (I p, out) and extracting a current spectral portion (IT) corresponding to the natural frequency (f _N ) (330), wherein the current spectral portion (IT) corresponds to the extracted current signal having a delimited spectral portion near the natural frequency (f _N ),
The method further comprises comparing the extracted voltage spectral portion (VT) and the extracted current spectral portion (IT) with their respective single thresholds (t _hv , t _hi ) (340v, 340i). The method according to 6, characterized in that the predetermined detection frequency (f _det ) of the analog pre-filtering is in the range of 1 kHz to 2 kHz. The Fast Fourier Transform (314V) of the measured voltage is performed with an analysis time in the range of 4ms to 10ms.
The method according to claim 6, wherein the fast Fourier transform (324i) of the measured current is performed with an analysis time in the range of 100 ms to 300 ms. The method according to claim 2, wherein the analog passband Butterworth filtering is a second-order analog passband Butterworth filtering. DC voltage (V _line A railway overhead line (12) carrying ) and a railway traction device (11) that absorbs or injects current (I _p Arcs (A, V) generated between the pantograph (11a) of the railway traction device (11) and the rail traction device (11) that collect the air. _arc A structure (200, 300) that detects ),
The pantograph (11a) has a predetermined natural frequency (f _N Includes an input low-pass filter that operates in )
The input low-pass filter has a voltage (V) between the pantograph shoe of the pantograph (11a) and the reference node at the input of the input low-pass filter. _p ) and the current (I) absorbed or injected by the railway traction device (11). _p ) receives the and at the output section of the input low-pass filter, the filtered voltage (V) is sent to the railway traction device (11). _dsf ) to supply,
The aforementioned structure (200, 300) further comprises the voltage (V) between the pantograph shoe and the reference node. _p ) and the current (I) absorbed or injected by the railway traction device (11) _p The sensor module (11b) is configured to measure (110) the voltage (Vp, out) and the current (Ip, out), respectively,
The structure (200, 300) is configured to perform a step of the method according to any one of claims 1 to 9.