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

Abstract

DC voltage (V line ) and the current (I p ) and the pantograph (11a) of the traction device (11) that collects the arc (A, V) arc ), a method for detecting The pantograph (11a) has an input low-pass filter, The input low-pass filter is A given natural frequency (f N ) and At the input of the input low-pass filter, the voltage between the pantograph (11a), in particular the pantograph shoe, and a reference node (V p ) and the current (I p ) and At the input of the input low-pass filter, the filtered voltage (V dsf ) to the rail traction device (11), The method further comprises: The voltage (V p ) and the current (Ip) absorbed or injected by the rail traction device (11), and measure the measured voltage (V p,out ) and the measured current (I p,out ) (110) From the measured voltage (Vp,out), a predetermined detection frequency (f det ) is an extracted voltage signal (V bp ;V filt VT) (120;220;320); The measured current (I p,out ) to find the natural frequency (f N ) is the extracted current signal (I bp ;I filt ;IT) (130;230;330); The extracted voltage signal (V bp ;V filt VT) and the extracted current signal (I bp ;I filt ;IT) and their respective thresholds (t hv , t hi ) and compare steps (140; 240v, 240i; 340v, 340i), The comparison operation (step 140) compares the extracted voltage signal (V bp ;V filt VT) and the extracted current signal (I bp ;I filt ;IT) amplitudes are measured at their respective thresholds (t hv , t hi ) or more (steps 150 and 250), and if the verification result is positive, a step (160) of issuing a signal indicating that an arc (A) has been detected.

Description

[Technical Field]

[0001] 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.

[0002] One or more embodiments may be applied to applications for collecting energy consumption-related data and transmitting it to a ground data collection system. [Background technology]

[0003] In most electric railway systems, power is transmitted from the power source to the traction device (locomotive or electric train) via a sliding contact between the overhead line (OHL) and the pantograph. The pantograph is a servo-operated current collector mounted on the roof of the train, which applies and controls the force of the contact strip to the contact line. Because a large amount of power (up to approximately 8 MW) is transmitted from the OHL to the carbon blades of the pantograph through a contact area of ​​a few millimeters square, the current collector is one of the most important components of a railway power system.

[0004] 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 an increase in arc events, which can result in a decrease in power quality and accidents.

[0005] Therefore, counting arc discharges is desirable to monitor the condition of the pantograph and overhead lines. By combining such tools with data collection systems and widely disseminating them to all vehicles, it is possible to contribute to predictive maintenance of equipment involved in slip contact.

[0006] In particular, in the future, if all locomotives are equipped with devices to detect arc events and transmit the number of arc events to a ground data collection system, 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).

[0007] In the current system, the condition of the pantograph shoe (the element that contacts the OHCL) is monitored by registering it with a video system, but this requires the installation of a video camera, and it has been difficult to identify arc events from the acquired images. [Overview of the Initiative]

[0008] Based on the above explanation, there is a need for solutions to overcome one or more of the shortcomings outlined earlier.

[0009] 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 the relevant detection arrangement.

[0010] The claims are an integral part of the technical teachings of the disclosure provided herein.

[0011] 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.

[0012] 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 spectral portions delimited around a predetermined natural frequency from the measured current absorbed or injected by the locomotive includes performing analog passband Butterworth filtering of the order of second order, particularly around 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.

[0013] 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.

[0014] In a modified embodiment, the natural frequency is in the range of 15 Hz to 30 Hz, and the bandwidth of the analog passband Butterworth filtering is, in particular, 11.2 Hz.

[0015] In a modified embodiment, the comparison operation includes delaying the comparison output of the extracted voltage portion.

[0016] 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.

[0017] This includes comparing the voltage tone and the current tone with their respective single threshold values.

[0018] In a modified embodiment, the detection frequency of the analog pre-filtering is in the range of 1 kHz to 2 kHz.

[0019] 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.

[0020] 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 includes 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.

[0021] The claims are an integral part of the technical teachings provided herein with reference to embodiments.

[0022] One or more embodiments are described, only as non-limiting examples, with reference to the attached figures. [Brief explanation of the drawing]

[0023] [Figure 1] Figure 1 is a schematic diagram providing a circuit description for arc events. [Figure 2A] Figure 2A is a time-lapse diagram showing the voltage and current behavior in a pantograph when an arc event is present. [Figure 2B] Figure 2B is an enlarged time diagram of the figure in Figure 2A. [Figure 3] Figure 3 is a flowchart illustrating a general embodiment of the method described herein. [Figure 4] Figure 4 is a schematic diagram of an arrangement for implementing the first embodiment of the method described herein. [Figure 5] Figure 5 is a time diagram of the voltage quantity in the embodiment shown in Figure 4. [Figure 6] Figure 6 is a time diagram of the current flow in the embodiment shown in Figure 4. [Figure 7] Figure 7 is a time diagram of the voltage and current quantities in the embodiment shown in Figure 4. [Figure 8] Figure 8 is a schematic diagram of an arrangement that implements the second embodiment of the method described herein. [Figure 9] Figure 9 is a time diagram of the voltage quantity in the embodiment shown in Figure 8. [Figure 10] Figure 10 is a time diagram of the current flow in the embodiment shown in Figure 8. [Figure 11] Figure 11 is a time diagram of the voltage and current quantities in the embodiment shown in Figure 8. [Modes for carrying out the invention]

[0024] The following description illustrates one or more specific details for the purpose of providing a deeper understanding of the examples of the embodiments described herein. Embodiments can be obtained without one or more specific details, or by using other methods, components, materials, etc. Otherwise, known structures, materials, or operations are not illustrated or described in detail so as not to obscure certain aspects of the embodiments.

[0025] Any reference to “one embodiment” or “one embodiment” within the framework of this specification is intended to indicate that a particular configuration, structure, or characteristic described in relation to an embodiment is configured in at least one embodiment. Accordingly, 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.

[0026] Furthermore, specific conformations, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0027] The references used herein are provided solely for convenience and therefore do not define the scope of protection or the scope of the embodiments.

[0028] 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.

[0029] The drawings are simplified and not to an accurate scale.

[0030] 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. Although 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 "Pantograph-to-OHL Arc: Conducted Effects in DC Railway Supply System" by G. Crotti et al., IEEE Transactions on Instrumentation and Measurement, Vol. 68, No. 10, pp. 3861-3870, October 2019.

[0031] Figure 1 is a schematic diagram providing a simple circuit description of an arc event between absorption (positive) in a traction device or generation of current by the traction device (negative), the latter of which can occur during the braking phase.

[0032] Therefore, Figure 1 shows the DC supply voltage V supplied from the power supply system 13 by the pantograph 11a. line A traction device 11, such as a locomotive, is shown, coupled to an overhead wire 12 that carries the traction device.

[0033] Due to its nature, the pantograph 11a is normally supplied with a DC voltage V line The pantograph 14 is in contact with the overhead wire 12, but the voltage generator generates an arc voltage V between the overhead wire 12 and the pantograph 14 for one of the reasons mentioned above. arc This represents the formation of an arc A having I p This indicates the current flowing between the overhead wire 12 and the pantograph 11a.

[0034] In Figure 1, this is represented by the equivalent circuit of the coupling between the overhead wire 12 and the pantograph 11a, and the input filter 15 represents the input stage of the pantograph 14. As shown in the figure, the DC power supply voltage V line The arc voltage V arcIt is coupled to a terminal separated from the input terminal of the input filter 15 by an equivalent voltage generator representing. Thus, the pantograph voltage V, which is the input voltage of the input filter 15 p is V line - V arc and 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 with respect to the overhead line 12.

[0035] As shown in FIG. 1, the pantograph voltage V p is formed between the pantograph 11a and a reference node, for example, a ground reference. Usually, the reference node is at zero voltage or a lower potential with respect to the pantograph voltage V p or the DC supply voltage V line . In an embodiment, the reference node can be represented by a rail.

[0036] The input filter 15 is a traction device 11, that is, a low-pass input stage filter of a locomotive, and is generally present in a DC locomotive. This filter plays an important role in understanding the electrical conduction effect caused by an arc. This is schematized in FIG. 1 as an LC filter in which a series inductor Lif and an output capacitor C if are arranged in parallel. At the terminals of the series inductor L if and the output capacitor Cif which is the reference node, a filtered DC voltage V dsf for supplying the electric motor of the traction device 12 is formed. As shown in FIG. 1, thus also, the filtered DC voltage V dsf is referred to the reference node, for example, the ground reference as the pantograph voltage V p . More generally, all the potentials of the input filter 15 including the input node where the pantograph voltage V p is formed are referred to such a reference node which can be the ground reference as described above or is represented by a rail in an embodiment. The rail does not necessarily have to be at zero voltage, V line , Vp , V dsf A low potential is sufficient for the node.

[0037] Figure 2A shows the voltage V at the pantograph when arc event A is detected while locomotive 11 is absorbing current. p and current I p This is a time diagram showing the behavior.

[0038] Figure 2B is a time-domain enlarged view of arc A in Figure 2A, showing the same electric quantity.

[0039] Electric arc A occurs when the traction device 11 is absorbing the current, at pantograph voltage V p The voltage dip induces undulation when the traction device 11 is injecting current into the overhead line 12. Such rapid fluctuations induce vibrations in the secondary low-pass filter 15, causing the pantograph current I p This will be reflected.

[0040] 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.]

[0041] The solution described here utilizes the conduction effect generated by the arc, and generally involves the pantograph voltage V between the pantograph 11a and the reference node, as shown in the flowchart of Figure 3 illustrating Embodiment 100 of the method. pAnd the current I absorbed or injected by the railway traction device 11 p The measured voltage V was then measured. p,out and the measured current I p,out Obtain each of them (step 110), Measured voltage V p,ou From t, a predetermined detection frequency f det Spectral portion V delimited around it bp An extracted voltage signal having a given detection frequency f, i.e., after, for example, bandpass filtering. det Extract a signal having a spectrum spanning a limited frequency range or band around (step 120), The measurement current I absorbed or injected by the locomotive p,out From there, the predetermined natural frequency f of the input filter N Peripheral delimited spectral portion I bp Extract the current signal having (step 130), Delimited spectral portion V bp The amplitude of the extracted voltage signal and the separated spectral portion I bp The amplitude of the extracted current signal having the respective threshold and voltage threshold t hv or current threshold t hv Compared to (step 140), The comparison operation 140 determines the separated spectral portion V bp The amplitude of the extracted voltage signal and the delimited spectral portion I bp Both the amplitudes of the extracted current signals having the respective threshold t hv , t hv Verify whether it exceeds (step 150), If it exceeds the limit, the detection AD of arc A is notified by a signal (step 160).

[0042] Referring to Figure 4, a detection setup 200 is shown, which represents a first embodiment of the method described here that is more analog-oriented.

[0043] As schematically shown in Figure 4, the pantograph voltage V between the pantograph 11a and the reference node p and the current I absorbed or injected by the railway traction device 11 p Measure the measured voltage V p,out and the measured current I p,out Step 110, which yields each of these, 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.

[0044] Such a measured voltage V p,out From there, a predetermined detection frequency f det Extracted voltage signal V with spectral portion Vfilt delimited around it bp Step 120, which extracts the detection frequency f, is to use any, i.e., a predetermined, detection frequency f det This is realized by filtering by a passband second-order Butterworth filter 220 centered on the frequency f. det The value can be selected within the range of 1kHz to 3kHz, and the bandwidth may be, for example, 143Hz. This is an exemplary value, and different bandwidth values ​​are possible, chosen 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.

[0045] Spectral portion V in this embodiment bp The separated extracted voltage signal is the filtered analog voltage V filt It is represented by [this].

[0046] The measured current I absorbed or injected by the locomotive p,out From there, the predetermined natural frequency f of the input filter N Nearby delimiter spectral portion I bpStep 130, which extracts an extracted current signal having the natural frequency f of the low-pass filter 15 in the input stage of the locomotive 11, N This is achieved through filtering by a second-order Butterworth filter 230 with a passband centered on the natural frequency f. N The value of depends on the resonant frequency of the locomotive's input filter stage 15, for example, the resonant frequency of the LC resonant circuit that forms the passband second-order Butterworth filter 230. Natural frequency f in the embodiment N The value can be selected within the range of 15Hz to 30Hz, and the bandwidth may be, for example, 11.2Hz. The same considerations regarding the bandwidth value of filter 220 also apply here. Delimited spectral portion I bp The extracted current signal having the filtered current I filt It is manifested by [this].

[0047] Delimited spectral portion V filt The amplitude of the extracted voltage signal and the separated spectral portion I filt The amplitude of the extracted current signal having the respective threshold t hv ,t hi To perform a comparison 140, then, each filtered signal V filt ,I filt In particular, the positive and negative thresholds, +t, respectively. hv ,-t hv and +t hi ,-t hi It operates between and is processed by threshold comparators 240v and 240i, respectively. The filtered signal V filt , I filt If the voltage is higher than the threshold, then for the voltage, t hv Regarding the current, thi, the output signals of the respective threshold comparators 240V and 240I t hv_out , t hi_out If it is logically 1, it is logically 0 otherwise. Threshold t hv ,t hi The range of variation is summarized in Table 1 below.

[0048]

Table 1

[0049] The output signal t of the voltage comparator 240v hv_out is delayed by a delay D in the delay block of the time delay device 245. In the illustrated example, the delay D is 5 ms, and the delayed output signal t hv_out_D is supplied. The value of the delay D is selected to compensate for the different time delays introduced by the filters 220 and 230.

[0050] The output signals t hv_out_D , t hi_out from the comparators 240v and 240i are sent to the AND logic gate 250 that implements the verification 150 when the comparison operation 140 indicates that both the amplitude of the extracted voltage signal having the segmented spectrum portion V filt and the amplitude of the extracted current signal having the segmented spectrum portion V filt exceed their respective threshold values t hv , t hi .

[0051] The output signal of the AND logic gate is equal to the flag AD equal to 1 only when both of the output signals t hv_out , t hi_out are 1, that is, when they exceed their respective threshold values t hv , t hi . This represents an affirmative or positive response to the verification step 150, and thus, the detection of the arc is signaled at step 160. Otherwise, the flag AD is zero, meaning that no arc occurs if either one of the output signals t hv_out , t hi_out is zero, that is, less than their respective threshold values t hv , t hi .

[0052] In FIG. 5, the measured voltage V p,out , the filtered voltage V filt , and the delayed output signal t hv_out_D are shown as functions of time t. Also, the delayed output signal t hv_out_DThe delay D is also shown relative to the oscillation that occurred before the threshold was exceeded. Such a delay D is, of course, also present in the next oscillation determined by arc A.

[0053] Figure 6 shows the measured current I p,out , filtering current I filt and current output signal t hi_out However, it is shown as a function of time t.

[0054] Figure 7 shows the measured voltage V p,out and the measured current I p,ou This shows the result of overlaying t as a function of time t onto the same graph, with the resulting flag AD displayed. When flag AD becomes 1, an arc has been detected.

[0055] Referring to Figure 8, a second embodiment of the method described here is shown, which is more digitally oriented.

[0056] As schematically shown in Figure 8, the pantograph voltage Vp between the pantograph 11a and the reference node and the current I absorbed or injected by the railway traction device 11 are shown. p Measure the measured voltage V p,out and the measured current I p,out Step 110, which yields each of these, is performed by the composite current-voltage converter 11b.

[0057] Measured voltage V p,out However, before step 120, a pre-filter is also performed by analog filter 312, which is essentially a low-pass band filter. This frequency response is flat at low frequencies and has a predetermined detection frequency f det (In this embodiment, it resonates preferably within the range of [1÷2] kHz), so only fast transients are utilized by the filter. The filter response of filter 312 to voltage for an actual arc event is reported in Figure 9, which is the output t of comparator 340v, which will be described better below. hv_out In addition, the analog-filtered voltage V output by the analog filter 312 pfDetection frequency f det Measured voltage V p,out , and amplitude V pf @f det The time diagram is shown. Thus, the voltage measurement step 110 is substantially followed by such analog pre-filtering of the measured voltage by the analog filter 312 having a resonant frequency at the detection frequency, and then the analog filtered voltage V by the analog-to-digital voltage conversion module 314v. pf Digital acquisition is performed, and the digitally measured voltage V p,d This is generated.

[0058] Furthermore, each analog-to-digital current conversion module 314i measures the current I in synchronization with the voltage measurement signal. p,out Obtain the digital measurement current I p,d Generates.

[0059] Next, consider this digitally measured voltage V p,d Therefore, the resonant frequency f of the upstream special filter 312 det In the FFT block 320 for detection, a Fast Fourier Transform (FFT) is applied to a predetermined detection frequency f det The spectral portion V is divided around the boundary. bp (In this case, the extracted voltage signal having tone VT) is subjected to the step of extracting the extracted voltage signal.

[0060] Similarly, the digitally measured current I p,d As shown in Figure 11, the natural frequency f of the low-pass filter 15 in the input stage of the locomotive 11 is N In the FFT block 330 for detection, an FFT is performed, and the extracted portion is current tone IT t This is extracted.

[0061] Then, tone VT and IT are measured in their respective threshold comparators 340v and 340i, respectively, and their respective threshold t hv ,t hi It is compared to the following. When the amplitude of tone VT and IT is higher than the threshold, for the voltage signal t hv Regarding the current signal,hi The output signals of the respective comparators 340V and 340i are t hv_out , t hi_out If it is 1, it is 0 otherwise. Figure 10 shows the output t of the current comparator 340i. hi_out The measured current at 15Hz and the tone IT are shown as time functions.

[0062] In this case, the output signals t from comparators 340v and 340i are also considered. hv_out , t hi_out The comparison operation 140 determines whether the amplitudes of both the extracted voltage spectrum portion, in this case the voltage tone VT, and the extracted current spectrum portion, in this case the current tone IT, are equal to their respective thresholds t. hv , t hi If it indicates that it exceeds the threshold, it is sent to the AND logic gate 250 which specifically indicates verification 150.

[0063] The output signal of the AND logic gate 250 is output signal t hv_out ,t hi_out Both are 1, i.e., each threshold t hv ,t hi Flag AD is equal to 1 only if it exceeds . This represents a positive or positive answer to verification step 150, and therefore arc detection is signaled in step 160. Otherwise, flag AD is equal to the output signal t hv_out ,t hi_out If either of the thresholds t is zero, that is, if either threshold t is zero, hv ,t hi If the following conditions are met, the measured voltage V is superimposed on the same graph as a function of time t, as shown in Figure 11. p,out and the measured current I p,out The result shows flag AD, which is zero, meaning no arc occurred. When flag AD becomes 1, an arc has been detected.

[0064] 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 to be as small as possible in order to have a good approximation of the steady state. In addition to this, good spectral resolution is also required, and therefore sufficient analysis time is necessary to detect the tone. For this reason, it is preferable that the detection of the resonant frequency of the upstream special filter has an analysis time in the range of [4~10] ms, and the detection of the natural frequency of the low-pass filter in the locomotive input stage has an analysis time in the range of [100~300] ms.

[0065] The selection of thresholds applied to the 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.

[0066] [Table 2]

[0067] This solution allows for counting arc events to monitor the condition of both the pantograph and the overhead connecting wires without installing any other devices on the locomotive roof, in addition to the already installed voltage / current converter.

[0068] This will enable widespread implementation of this solution in all locomotives involved in data collection systems, and as a result, it will make a valuable contribution to predictive maintenance of devices related to sliding contact, particularly predictive maintenance of the quality of contact between the pantograph and the OHL.

[0069] 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 means the problem is related to the pantograph.

[0070] 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.

[0071] 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

1. DC voltage (V line A railway overhead line (12) that carries the current (I) absorbed or injected by the railway traction device (11). p Arcs (A, V) generated between the pantograph (11a) of the railway traction device (11) and the railway traction device (11) that collect the arcs (A, V) arc A method for detecting ) The pantograph (11a) has an input low-pass filter, The aforementioned input low-pass filter is A predetermined natural frequency (f N ) operates with, At the input section of the input low-pass filter, the voltage (V) between the pantograph shoe of the pantograph (11a) and the reference node is... p ) and the current (I) absorbed or injected by the railway traction device (11) p ) and At the input section of the aforementioned input low-pass filter, the filtered voltage (V dsf ) is supplied to the railway traction device (11), The above method further, the voltage (V p between the pantograph shoe and the reference node), and the current (Ip) absorbed or injected by the railway traction device (11), measure the measured voltage (V p，out ), and the measured current (I p，out ), respectively, and obtain steps (110); From the measured voltage (Vp, out), a predetermined detection frequency (f det Extracted voltage signal (V) having a spectral portion delimited around ) bp ;V filt The steps include extracting VT (120; 220; 320) and The measurement current (I) absorbed or injected by the aforementioned railway traction device p，out From ), the given natural frequency (f N Extracted current signal (I) having a spectral portion delimited around ) bp ;I filt The steps to extract IT (130; 230; 330), The extracted voltage signal (V) having a delimited spectral portion bp ;V filt ; The extracted current signal (I) has the amplitude of VT) and a separated spectral portion. bp ;I filt The amplitude of IT and the respective thresholds (t hv , t hi The steps to compare (140; 240v, 240i; 340v, 340i), The comparison step (140) is the extracted voltage signal (V) having the separated spectral portion. bp ;V filt ; The extracted current signal (I) having the amplitude of VT) and the separated spectral portion bp ;I filt Both amplitudes of ;IT) are equal to their respective thresholds (t hv , t hi A method comprising the step of verifying whether or not it indicates that the value is greater than or equal to (step 150; 250), and if the verification result is positive, emitting a signal that an arc (A) has been detected (step 160).

2. The method according to claim 1, The measured voltage (V p，out From ) a predetermined detection frequency (f det Extracted voltage signal (V) having a spectral portion delimited around ) bp ;V filt The step of extracting (120; 220; 320) the predetermined detection frequency (f det The step (220) includes performing analog Butterworth filtering or resonant filtering around ) From the measurement current (Ip, out) absorbed or injected by the aforementioned railway traction device, the given natural frequency (f N Extracted current signal (I) having a spectral portion delimited around ) bp ;I filt The step of extracting the (130; 230; 330) of the input low-pass filter (15) is the natural frequency (f N This includes a step (320) of performing analog passband Butterworth filtering centered on ), The comparison step (140; 240V, 240i; 340V, 340i) is performed by extracting the voltage (V filt ) and the extracted current (I filt A method comprising the step of comparing (240v, 240i) using respective threshold comparators.

3. The method according to claim 2, The predetermined detection frequency (f det The method is such that the frequency range is from 1 kHz to 3 kHz, and the bandwidth of the analog Butterworth filtering (220) is 143 Hz.

4. The method according to claim 2, The aforementioned natural frequency (f N ) is in the range of 15Hz to 30HzKHz, The bandwidth of the aforementioned analog bandpass Butterworth filtering is 11.2 Hz, according to the method.

5. 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).

6. The method according to claim 1, The step (110) of measuring the voltage involves the predetermined detection frequency (f det The voltage (V) measured by an analog filter having a resonant frequency in ) p，out ) is pre-filtered with an analog filter (312) to obtain an analog filtering voltage (V pf After obtaining the analog filtering voltage (V pf This includes digitally acquiring (314V), The step (110) of measuring the current is the analog filtered voltage (V pf Synchronized with the acquisition of the measured current (I p，out This includes digitally acquiring (314i) The measured voltage (V p,out From the predetermined detection frequency (f det The extracted voltage signal (V) has a spectral portion delimited around it. bp ;V filt The step of extracting the analog filtering voltage (V) (120; 220; 320) is performed by the analog filtering voltage (V) pf The Fast Fourier Transform (320) is performed on the predetermined detection frequency (f det The process involves extracting a voltage spectral portion (VT) corresponding to the given value, wherein the voltage spectral portion (VT) corresponds to an extracted voltage signal having a delimited spectral portion near the predetermined detection frequency (f det), The measured current (I) absorbed or injected by the aforementioned railway traction device p，out From the predetermined natural frequency (f N The extracted current signal (I bp ;I filt The step of extracting IT (130; 230; 330) involves performing a fast Fourier transform on the measured current (Ip, out) and the natural frequency (f N (330) extracting a current spectral portion (IT) corresponding to the above, wherein the current spectral portion (IT) corresponds to an extracted current signal having a delimited spectral portion near the natural frequency (f N), The method further comprises setting the extracted voltage spectral portion (VT) and the extracted current spectral portion (IT) to a single threshold (t hv , t hi Methods including comparing (340V, 340i) with other methods.

7. The predetermined detection frequency (f) of the analog pre-filtering. det The method according to 6, characterized in that the frequency is in the range of 1 kHz to 2 kHz.

8. 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.

9. The method according to claim 2, wherein the analog passband Butterworth filtering is a second-order analog passband Butterworth filtering.

10. A structure (200, 300) 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) includes an input low-pass filter that operates at a predetermined natural frequency (f N), The input low-pass filter receives, at its input, the voltage (V p) between the pantograph shoe of the pantograph (11a) and the reference node, and the current (I p) absorbed or injected by the railway traction device (11), and at its output, supplies the filtered voltage (V dsf) to the railway traction device (11). The structures (200, 300) further include a sensor module (11b) configured to measure (110) 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 to obtain the measured 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.

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