Monitoring of transmission lines

Abstract

The invention relates to a system comprising a coupling device (210) and a data processing device (218), which data processing device (218) is designed to provide an excitation signal (SE) such that an internal signal (Φ) occurs in the coupling device (210), which internal signal (Φ) has a deformation caused by a current (I0) to be measured, to obtain a measurement signal (Sm) for a variable (Vm), which variable (Vm) is sensitive to the deformation, to provide a compensation signal (Sc) to counteract the deformation, and to evaluate the current (I0) to be measured in dependence on the compensation signal (Sc). The data processing device (218) is further designed to analyze the measurement signal (Sm) and to detect a fault on a transmission line (118) in dependence on the analysis.

Description

Technical Field

[0001] This invention relates to the monitoring of transmission lines. More specifically, this invention relates to a system for monitoring transmission lines, a power distribution system including such a monitoring system, an aircraft including such a power distribution system, a method for monitoring transmission lines, and a corresponding computer program thereof. Background Technology

[0002] Patent documents FR3083321A1 and FR3083365A1 respectively describe a system for monitoring transmission lines, the types of which include: - A coupling device, connected to a transmission line, to receive current from the transmission line; - A data processing device, connected to a coupling device, is designed as follows: • Provide an excitation signal to the coupling device, causing an internal signal to appear in the coupling device, which has a distortion caused by the current to be measured; • Obtain a signal for measuring a variable in the coupling device, the signal of which is sensitive to distortions in the internal signal; • Provide a compensation signal to the coupling device to compensate for the deformation based on the measurement signal; and • Evaluate the current to be measured based on the compensation signal.

[0003] More specifically, in these documents, the monitoring system includes a flux valve current sensor.

[0004] It may be desirable to provide a system for monitoring transmission lines that allows for better monitoring without adding measuring equipment. Summary of the Invention

[0005] Therefore, a system for monitoring transmission lines of the above type is proposed, characterized in that the measurement signal is also sensitive to faults present on the transmission line, and the data processing device is also designed to analyze the measurement signal and detect faults on the transmission line based on the analysis.

[0006] Therefore, in addition to enabling the measurement of current on transmission lines, the monitoring system according to the invention also enables the detection of faults on transmission lines using existing current measurement components.

[0007] Optionally, the coupling device includes a transformer with a ferromagnetic core, the internal signal being the total magnetic flux present in the core, and the internal signal combining the excitation magnetic flux caused by the excitation signal, the current magnetic flux caused by the current to be measured, and the compensation magnetic flux caused by the compensation signal to substantially cancel out the current magnetic flux.

[0008] Alternatively, the analysis of the measurement signal includes: comparing the measurement signal with at least one template, and wherein a fault on the transmission line is detected starting from the moment when the measurement signal is outside the at least one template.

[0009] Alternatively, the excitation signal may also include an oscillation signal.

[0010] Alternatively, the oscillation signal includes the sum of a sine wave at the fundamental frequency and a sine wave at the third harmonic, wherein the sine wave at the third harmonic is the sine wave at three times the fundamental frequency.

[0011] Alternatively, the excitation signal is generated via a coupling device to transmit a signal on the transmission line, and the data processing device is further designed to encode the data to be transmitted into an encoded signal, wherein the excitation signal includes the encoded signal, such that the transmitted signal includes the data to be transmitted.

[0012] Alternatively, the average value of the encoded signal is zero.

[0013] Alternatively, the fundamental frequency of the encoded signal may be higher than the fundamental frequency of the oscillation signal.

[0014] Alternatively, at least one template includes a global template that, on the one hand, tracks the change in the oscillation signal of the measurement signal caused by the oscillation signal of the excitation signal, and on the other hand, tracks the envelope of the encoded signal of the measurement signal caused by the encoded signal of the excitation signal.

[0015] Alternatively, at least one template includes a local template that tracks changes in the encoded signal of the measurement signal caused by the encoded signal of the excitation signal.

[0016] Alternatively, the oscillation signal may include a series of rising and falling points, wherein the encoded signal appears only on one of the rising and falling points.

[0017] Alternatively, the measurement signal includes a series of rises and falls, respectively corresponding to a series of rises and falls of the oscillation signal, and wherein the data processing device is further designed to decode the encoded signal appearing on another of the rises and falls of the measurement signal.

[0018] Alternatively, the transmission line is a coaxial cable.

[0019] A power distribution system is also proposed, including: -power supply; - Electrical load; - A transmission line that connects the electrical load to the power source, enabling the power source to supply power to the electrical load; -A system for monitoring transmission lines according to the present invention.

[0020] Alternatively, the power supply is a DC voltage source, preferably greater than 100V.

[0021] An aircraft including a power distribution system according to the invention is also proposed.

[0022] A method for monitoring transmission lines is also proposed, which uses a coupling device connected to the transmission line to receive current from the transmission line, the method comprising: - Provide an excitation signal to the coupling device so that an internal signal appears in the coupling device, which has a distortion caused by the current to be measured; - Obtain a signal for measuring a variable of the coupled device, the signal of which is sensitive to distortions in the internal signal; - Based on the measured signal, a compensation signal is provided to the coupling device to counteract the deformation; and - Evaluate the current to be measured based on the compensation signal; The method is characterized in that the measurement signal is also sensitive to faults present on the transmission line, and the method further includes: analyzing the measurement signal and detecting faults on the transmission line based on the analysis.

[0023] A computer program that can be downloaded from a communication network and / or stored on a computer-readable medium is also proposed, characterized in that, when executed on a computer, the computer program includes instructions for performing steps of the method according to the invention. Attached Figure Description

[0024] The invention will be better understood in conjunction with the following description, which is given by way of example only and with reference to the accompanying drawings.

[0025] Figure 1 This is a schematic diagram of a power distribution system implementing the present invention, which includes transmission lines.

[0026] Figure 2 It is used for monitoring Figure 1 A schematic diagram of the transmission line system.

[0027] Figure 3 It is a graph showing the magnetic flux saturation in a ferromagnetic core.

[0028] Figure 4 The sum of signals that form the excitation signal is shown.

[0029] Figure 5 The signal measured by the monitoring system is shown.

[0030] Figure 6 The first template surrounding the signal measured by the monitoring system is shown.

[0031] Figure 7A second template surrounding the signal measured by the monitoring system is shown.

[0032] Figure 8 The distortion in the measured signal caused by the first fault in the transmission line is shown.

[0033] Figure 9 The distortion in the measurement signal caused by a second fault in the transmission line is shown.

[0034] Figure 10 It is for monitoring according to another embodiment Figure 1 A schematic diagram of the transmission line system: Detailed Implementation

[0035] Reference Figure 1 An example of a power distribution system 100 that implements the present invention will now be described.

[0036] In the described example, the power distribution system 100 is used for implementation in the aircraft.

[0037] The system 100 first includes a power source 102 designed to provide a direct current (DC) voltage V. Preferably, the DC voltage V is a high voltage, for example, at least 100V, and even more preferably at least 1000V. Therefore, the power source 102 includes a positive terminal "+" and a negative terminal "-", and a DC voltage V is provided between the positive terminal "+" and the negative terminal "-". The power source 102 is designed to provide, for example, at least 100kW of power. The power source 102 includes, for example, one or more of the following: a battery, an alternator driven by a turbine (engine or auxiliary generator), a fuel cell, and a supercapacitor.

[0038] The system 100 also includes a first positive terminal connection 104 and a first negative terminal connection 106, which are respectively connected to the positive terminal and the negative terminal of the voltage source 102.

[0039] System 100 also includes an electrical load 110, which is powered by power supply 102. The aircraft 100 includes a second positive connection 112 and a second negative connection 114, respectively connected to the two terminals of the electrical load 110. The electrical load 110 includes one or more of, for example, an electric propulsion motor, an electric landing gear or flight control motor, and a de-icing heating resistor.

[0040] In order to transfer electrical energy from power source 102 to electrical load 110, aircraft 100 also includes a transmission line that connects two positive terminals 104 and 112 to each other, and also connects two negative terminals 106 and 114 to each other.

[0041] Preferably, the transmission line is a coaxial cable 118. The coaxial cable 118 firstly includes a conductive central core 120 and a first dielectric sheath 122 (referred to as the inner sheath) surrounding the central core 120. The coaxial cable 118 also includes a shield 124 surrounding the first dielectric sheath 122. The shield 124 is, for example, in the form of a cylindrical mesh. The coaxial cable 118 also includes a second dielectric sheath 126 (referred to as the outer sheath) surrounding the shield 124.

[0042] Therefore, positive connections 104 and 112 are connected to each other via the central core 120, while negative connections 106 and 114 are connected to each other via the shield 124. In this way, the central core 120 transmits the power supply current I from the power supply 102 to the electrical load 110, while the conductive shield 124 serves as a current return line from the electrical load 110 to the power supply 102.

[0043] Coaxial cable 118 possesses the unique advantage of iterative impedance, meaning its electrical characteristics remain substantially constant along its entire length. Other types of transmission lines may also exhibit this characteristic. Another advantage of coaxial cable 118 is that the low-potential shield 124 surrounds the high-potential central core 120. This means that if coaxial cable 118 is damaged, the shield 124 is the first thing to be visible. However, due to the low potential of shield 124, the danger of contact with it is minimal. More specifically, this low potential can be very close to the potential of the aircraft structure (e.g., less than 10V). In this case, the risk of electric shock is virtually zero.

[0044] Therefore, this type of transmission line can be easily used in aircraft with structures made of composite materials. However, since composite materials are electrically insulating, they cannot be used as electrical quality to form current return lines.

[0045] System 100 also includes a first system 128 and a second system 130 for monitoring transmission lines 118 respectively arranged on the first positive connection 104 and the second positive connection 112.

[0046] Reference Figure 2 An embodiment of monitoring system 128 will now be described, and monitoring system 130 is similar to monitoring system 128, for example.

[0047] The monitoring system 128 first includes a current sensor 202 with a flux valve.

[0048] The current sensor 202 is designed to measure the power supply current I. Since the measured power supply current I can be very high, in the described example, the current sensor 202 first includes a shunt 204, which on one hand includes a main branch 206 through which the majority portion I1 of the power supply current I passes; on the other hand, the shunt 204 also includes an auxiliary branch 208 through which a small portion I0 of the power supply current I (referred to as the auxiliary current I0) passes. The main branch 206 has a resistance S, while the resistance S of the auxiliary branch is much smaller than that of the main branch 206. An inductor L is also provided on the main branch 206.

[0049] The auxiliary current I0 and the power supply current I usually have a known fixed ratio. By measuring the auxiliary current I0, the power supply current I can be derived.

[0050] The current sensor 202 also includes a coupling device 210 connected to the transmission line 118 to receive an auxiliary current I0 from the transmission line 118.

[0051] In the described example, the coupling device 210 first includes a transformer 212 having a closed-loop ferromagnetic core 214 through which an auxiliary branch 208 passes to form the primary of the transformer 212.

[0052] The transformer 212 also includes a coil 216 wound on the magnetic core 214 and forming the secondary winding of the transformer 212. The coil 216 has two ends, one of which is connected to an electrical quality.

[0053] The coupling device 210 also includes an impedance Z, such as a resistor, in Figure 2 In the example shown, the impedance Z is connected to the second end of coil 216.

[0054] Figure 3 The diagram illustrates the variation of the total magnetic flux Φ in the magnetic core 214 as a function of the excitation H. It can be seen that this variation reveals two saturation regions for the total magnetic flux Φ: one saturation region, called Z+, occurs when the total magnetic flux Φ becomes very large in a positive direction; the other saturation region, called Z-, occurs when the total magnetic flux Φ becomes very large in a negative direction. In each saturation region, Z+ and Z-, although the excitation H becomes increasingly stronger, the total magnetic flux Φ increases less and less (whether the increase is positive or negative depends on the area); conversely, between the saturation regions Z+ and Z-, the total magnetic flux Φ as a function of the excitation H changes essentially linearly (ignoring hysteresis).

[0055] Back Figure 2When the auxiliary current I0 is not zero, the magnetic flux Φ0 of the current will appear in the magnetic core 214. Normally, the power supply current I is relatively constant, and so is the auxiliary current I0. Therefore, the magnetic flux Φ0 of the current is also relatively constant.

[0056] The current sensor 202 also includes a data processing device 218, which is designed to measure the auxiliary current I0 using the coupling device 210, and thus measure the power supply current I.

[0057] For example, data processing device 218 is a computer system including a data processing unit (e.g., a microprocessor) and main memory (e.g., random access memory, RAM) accessible by the processing unit. The computer system also preferably includes non-volatile memory, such as electrically erasable programmable read-only memory (EEPROM), programmable read-only memory flash (PROM-Flash), magnetoresistive random-access memory (M-RAM), or any other power-off functional memory technology for storing data. For example, a computer program containing instructions for the processing unit is loaded into the main memory such that the processing unit can execute the instructions to implement the functions and modules of the data processing device 218 to be described.

[0058] Alternatively, these functions and all or part of the modules can be implemented as hardware modules, that is, as electronic circuits, such as via microwires, without involving computer programs. For example, these functions and modules can be programmable logic circuits, such as field-programmable gate arrays (FPGAs).

[0059] First, the data processing device 218 is designed to provide an excitation signal SE to the coupling device 210 to generate a total magnetic flux Φ together with the auxiliary current I0. In the absence of the compensation described later, the total magnetic flux Φ will have a distortion caused by the current magnetic flux Φ0 from the current to be measured I0.

[0060] More specifically, the excitation signal SE causes an excitation flux ΦE, and adds a current flux Φ0 to the excitation flux ΦE. The excitation flux ΦE is designed to oscillate between its maximum and minimum values ​​in the saturation regions Z+ and Z-, respectively. However, due to the current flux Φ0, the total flux Φ(ΦE+Φ0) will shift towards one of the two saturation regions Z+ and Z- (depending on the sign of the auxiliary current I0); thus, the total flux Φ is distorted compared to the case where the auxiliary current I0 (and its current flux Φ0) is zero. In the latter case, the saturation at the maximum and minimum values ​​is approximately the same; however, with the auxiliary current I0 present, one of the maximum and minimum values ​​will be more saturated than the other.

[0061] The data processing device 218 is also designed to provide a compensation signal Sc to the coupling device 210, so that the resulting compensation magnetic flux Φc is essentially canceled out by the current magnetic flux Φ0.

[0062] In the described example, when using a single coil 216, the two signals SE and Sc are added together to form a single total signal, denoted as St.

[0063] In order for the total signal St to generate the excitation flux ΦE and the compensation flux Φc, in the described example, the data processing device 218 includes a digital-to-analog converter 220 for converting the total signal St into a voltage Vt applied to the impedance Z and the terminals of the coil 216. In this way, the voltage Vt will generate a current i flowing through the impedance Z and the coil 216, thereby generating excitation in the magnetic core 214.

[0064] To generate the excitation signal SE, in the described example, the data processing device 218 includes a module 222 for generating an initial oscillation signal Se′. For example, the initial oscillation signal Se′ is preferably formed by a sine wave at at least one fundamental frequency and a sine wave at a third harmonic (i.e., three times the fundamental frequency). For example, the initial oscillation signal may consist only of these two sine waves. Alternatively, the initial oscillation signal Se′ may be a triangular signal comprising a sine wave at the fundamental frequency and sine waves at odd harmonics of that fundamental frequency, particularly including a sine wave at the third harmonic.

[0065] To ensure that the saturation regions Z+ and Z- can be reached, in the described example, the data processing device 218 is further designed to multiply the initial oscillation signal Se′ by a saturation servo coefficient K to obtain the oscillation signal Se. Therefore, similar to the oscillation signal Se′, the oscillation signal Se comprises a sine wave at the fundamental frequency and a sine wave at the third harmonic. The method for calculating this servo coefficient K will be explained below.

[0066] The data processing device 218 also includes an encoding module 224 and an integrator 225. The encoding module 224 is designed to encode the data Tx to be transmitted into an initial encoded signal Sd′, and the integrator 225 is designed to integrate the initial encoded signal Sd′ into an encoded signal Sd. Then, the data processing device 218 is designed to add the encoded signal Sd to the oscillation signal Se to form the excitation signal SE.

[0067] Figure 4 An example is shown, consisting of the oscillation signal Se, the initial encoded signal Sd′, the encoded signal Sd, and the sum of these signals SE.

[0068] Preferably, the initial encoded signal Sd′ includes a clock signal. This makes it easier to recover the rhythm of the message, and therefore easier to recover the data.

[0069] Even more preferably, the average value of the initial encoded signal Sd′ is zero, and therefore, the average value of the encoded signal Sd is also zero. In this way, the average value of the partial excitation flux ΦE derived from the encoded signal is also zero, to avoid distortion of current measurement, which will be explained later.

[0070] Even more preferably, the initial encoded signal Sd′ is a square wave signal. Using a square wave is a simple way to represent binary data. The integrator 225 converts these square waves into a sawtooth pattern (i.e., a triangular signal).

[0071] For example, Manchester biphase coding can be used, which combines all three features mentioned above.

[0072] Preferably, the initial encoded signal Sd′ has a higher fundamental frequency than the oscillation signal Se.

[0073] Preferably, the initial encoded signal Sd′ exists only in the outer portion P of the oscillation signal Se of a predetermined length, and is centered at the maximum and minimum values ​​of the oscillation signal Se, respectively. In this way, the initial encoded signal Sd′ is almost free from the risk of deformation due to the saturation regions Z+ and Z-.

[0074] It will also be understood that if the oscillation signal Se comprises a series of rising and falling points. Preferably, the initial encoded signal Sd′ appears on only one of the rising and falling points (shown in the example as appearing on the rising point). Therefore, as will be explained later, the other of the rising and falling points can be used to receive data.

[0075] Back Figure 2 In the example described, the total signal St is therefore the sum of the encoded signal Sd, the excitation signal Se, and the compensation signal Sc: St = Se + Sd + Sc = SE + Sc = Sd + K * Se' + Sc.

[0076] In order to determine the compensation signal Sc and the servo coefficient K, the device 118 is also designed to obtain a signal for measuring the variable of the coupled device, which is sensitive to the deformation of the internal signal.

[0077] In the described example, the variable being measured is the voltage Vm at the terminals of coil 216. In fact, this voltage Vm is proportional to the derivative of the total magnetic flux Φ forming the internal signal, which is essentially equivalent to a high-pass filter. To measure the voltage Vm, in the described example, the data processing device 218 includes an analog-to-digital converter 226 to receive the voltage Vm as input, thereby converting the voltage Vm into a measurement signal Sm. Therefore, the fundamental frequency of the latter is equal to the fundamental frequency of the oscillation signal Se.

[0078] Under the deformation caused by the auxiliary current I0, a second harmonic appeared in the Sm signal.

[0079] Therefore, the data processing device 218 also includes an extraction module 228 for extracting the amplitude of the second harmonic of the measurement signal Sm. The extraction module 228 includes, for example, a multiplier designed to multiply the measurement signal Sm by a clock H2 synchronized with the second harmonic, and is followed by a low-pass filter.

[0080] Furthermore, the data processing device 218 is designed to set a compensation signal Sc based on the amplitude of the second harmonic of the measured signal Sm to compensate for the distortion, i.e., to make the compensation flux Φc compensate for the current flux Φ0. Therefore, this compensation allows for the cancellation of distortion in the total magnetic flux Φ. In the described example, this means that the second harmonic of the measured signal Sm will return to zero. To this end, in the described example, the data processing device 218 includes a setting module 230 for setting the compensation signal Sc based on the amplitude of the second harmonic of the measured signal Sm. This setting module 230 includes, for example, a proportional-integral regulator.

[0081] The data processing device 218 also includes a current evaluation module 232, which is designed to evaluate the auxiliary current I0 and therefore also evaluate the power supply current I from the compensation signal Sc.

[0082] To determine the coefficient K that allows the excitation flux ΦE to reach the two saturation regions Z+ and Z-, the data processing device 218 utilizes the characteristic that, by appropriately selecting the ratio between the amplitude of the sine wave at the fundamental frequency and the amplitude of the sine wave at the third harmonic of the oscillating signal Se, the third harmonic of the measured signal Sm will be canceled when reaching the saturation regions Z+ and Z-. Therefore, the data processing device 218 first includes a module 234 for extracting the third harmonic from the measured signal Sm. This extraction module 234 includes, for example, a multiplier designed to multiply the measured signal Sm by a clock H3 synchronized with the third harmonic, followed by a low-pass filter. Then, the data processing device 218 includes a module 236 for setting the coefficient K according to the amplitude of the third harmonic of the measured signal Sm. This setting module 236 includes, for example, a proportional-integral regulator.

[0083] It should also be understood that the excitation signal SE generates a voltage Vpe at the primary side of the transformer 212 (i.e., on the auxiliary branch 208) via the coupling device 210, and transmits the voltage Vpe on the transmission line 118.

[0084] As described above, monitoring device 130 is similar to monitoring device 128 and transmits voltage Vpr to the primary side of transformer 212. Preferably, monitoring devices 128 and 130 are synchronized with each other, for example, by a clock signal transmitted along with the coded signal Sd emitted by each of monitoring devices 128 and 130. This synchronization allows monitoring devices 128 and 130 to generate standing waves in transmission line 118 so that voltages Vpe and Vpr are superimposed on each other in a smooth manner.

[0085] Therefore, the measured voltage Vm represents this smooth superposition, and so does the measured signal Sm.

[0086] Therefore, refer to Figure 5 The measurement signal Sm includes the sum of the periodic signal Se*, the transmitted encoded signal Sde*, and the received encoded signal Sdr*.

[0087] A periodic signal Se* is generated based on the excitation signal Se from two monitoring devices 128 and 130. In the described example, this periodic signal Se* is essentially triangular with circular peaks because, on the one hand, transformer 212 acts as a shunt for converting the excitation signal Se, and on the other hand, the circular peaks are generated by the saturation effect of transformer 212 as detailed above.

[0088] The transmitted coded signal Sde* is generated based on the coded signal Sd sent by monitoring device 128, and the received coded signal Sdr* is generated based on the coded signal Sd sent by monitoring device 130. In the described example, due to the shunting function of transformer 212, the sawtooth wave of the coded signal Sd is converted into a square wave, so these coded signals (the transmitted coded signal Sde* and the received coded signal Sdr*) exist in the form of square waves.

[0089] Back Figure 2 It is understandable that the measured signal Sm is sensitive to faults present on transmission line 118. When current sensor 202 is operating, compensation for the current flux is effective, making everything that happens in coupling device 210 essentially as if the auxiliary current I0 and the compensation signal were both zero. The magnetic core 214 is traversed only by the excitation flux, which extends essentially in a linear region between the two saturation regions Z+ and Z-. Therefore, the secondary voltage Vm and current i are located at the primary (within a ratio), thereby generating a signal on the auxiliary branch 208 that is transmitted on transmission line 118. Since the excitation signal SE includes the encoded signal Sd, the transmitted signal includes the data Tx to be transmitted, allowing this data Tx to reach another monitoring system 130. Furthermore, all components connected to the primary of transformer 212 (especially transmission line 118) define the input impedance of transformer 212. When a fault occurs on transmission line 118, the input impedance of the transformer can be changed to cause a change in the primary voltage, thereby causing a change in the secondary voltage Vm.

[0090] This feature can be used to detect faults on transmission line 118. The data processing device 218 can also be designed to analyze the measurement signal Sm corresponding to the secondary voltage Vm, and based on this analysis, detect faults on transmission line 118.

[0091] For this purpose, the analysis of the measurement signal Sm specifically includes comparing the measurement signal Sm with at least one template, and performing fault detection on the transmission line 118 based on the portion of the measurement signal Sm located outside the at least one template.

[0092] In the example described, two templates were used.

[0093] Reference Figure 6 First, a global template GB is used, for example, to detect partial discharge and arcing (arc tracking) in transmission line 118. This global template GB will track changes in the envelope of the oscillation signal Se* and the encoded signals Sde*, Sdr*, above and / or below.

[0094] return Figure 2The data processing device 218 includes a module 238 for comparing the measurement signal Sm with a global template GB. Each moment when the measurement signal Sm leaves the global template GB is stored in the accumulator 240. These moments are sample moments whose values ​​are outside the global GB template, within the scope of the digital processing of sampling the measurement signal Sm.

[0095] Then, the data processing device 218 includes a statistical analysis module 242, which is designed to perform statistical analysis on the accumulated output times of the global template GB to detect faults on the transmission line 118. Figure 2 The parameter D1 in the diagram represents this detection. Therefore, when there are too many output moments of the global template GB, the statistical analysis module 242 will infer that there is a problem on the line, particularly partial discharge and / or arcing. For example, the global template GB is considered to be over-output when the ratio between the cumulative duration of the global template GB output within a predefined interval and the total duration of that interval is greater than a predefined threshold. This threshold is between 2% and 10%, for example, 5%. In the described example, the processing is digital; the statistical analysis module 242 counts, for example, the number of samples of the measurement signal Sm located outside the global template GB within a predefined interval, calculates the ratio of the counted sample count to the total number of samples in that interval, and compares this ratio to a predefined threshold.

[0096] The statistical analysis module 242 can also be designed to analyze the change of the spectrum of the measured signal Sm over time. More specifically, the statistical analysis module 242 is designed to search for high-frequency peaks and determine their amplitude and duration. An electric arc will generate a high-amplitude high-frequency peak that lasts for a period of time. Conversely, a partial discharge will generate a short, low-amplitude high-frequency peak. Therefore, when a high-frequency peak is detected, a problem on the line can be detected. Furthermore, based on the amplitude and duration of the high-voltage peak, the statistical analysis module 242 can distinguish between partial discharge and electric arc. For example, when the amplitude and duration of the high-frequency peak are respectively below predefined thresholds, partial discharge can be detected, while when the amplitude and duration of the high-frequency peak are respectively above these thresholds, electric arc can be detected. The frequency at which the peak is searched depends on the inherent characteristics of the line and the terminal components. Typically, peaks will be searched at frequencies above 10 MHz. Preferably, the search frequency should be limited to frequencies below 100 MHz, because attenuation above 100 MHz is generally large, and thus its effect is negligible. For example, perform a peak search in the 10MHz to 100MHz range, or perform a peak search in one or more intervals within the 10MHz to 100MHz range.

[0097] Preferably, the statistical analysis module 242 is designed to analyze a loop of one or more abnormal high-frequency peaks detected. When these high-frequency peaks first appear, these phenomena are usually very brief and have the characteristics of temporary interference, which have no impact on operation. On the other hand, if the loop meets the condition, it indicates that the changes are too frequent (e.g., when the loop is below a predefined threshold), and connection problems or even connection failures may occur in the near future. Therefore, in this case, it is preferable that the statistical analysis module 242 generates an alarm. For example, the alarm will be displayed on the screen or indicated by an indicator light. For example, the predetermined loop threshold is between 2 and 10 peak detections per hour on the transmission line.

[0098] refer to Figure 7 Furthermore, a precise template GP is used. This precise template GP tracks changes in the Sde* and Sdr* data signals above and / or below them. Therefore, preferably, it is possible to establish in real time as a function of the transmitted data Tx and the received data Rx.

[0099] return Figure 2 The data processing device 218 includes a module 244 for comparing the measurement signal Sm with a precise template GP. Each moment when the measurement signal Sm leaves the precise template GP is stored in an accumulator 246. In this way, the output time can represent the amplitude distribution of the measurement signal Sm. Within the scope of the digital processing that samples the measurement signal Sm, these moments are sample moments of the measurement signal Sm, whose values ​​lie outside the precise template GP.

[0100] Then, the data processing device 218 includes a statistical analysis module 248, which is designed to perform statistical analysis on the accumulated output moments of the precise template GP to detect faults on the transmission line 118. Figure 2 The parameter D2 in the table represents the detection.

[0101] Reference Figure 8 For example, the statistical analysis module 248 is designed to detect the degradation of the shield 124 of the coaxial cable.

[0102] If shielding 124 experiences partial damage, the transmitted signal will exhibit an impedance at the point of damage that differs from the normal characteristic impedance of the coaxial cable. Depending on whether the resulting impedance is higher or lower than the normal characteristic impedance, the signal can be amplified or attenuated on a portion of the level of the coded signal Sde* or Sdr*. Therefore, this portion will be transferred from the rest of the level. Thus, module 248 can be designed to determine the presence of this transferred portion and the length of this transferred portion (i.e., duration t). If module 248 detects the presence of the transferred portion, it can be designed to locate the fault along transmission line 118 based on time t and the known characteristics of transmission line 118.

[0103] Back Figure 2 It will also be understood that the measurement signal Sm comprises a series of rises and falls, which correspond respectively to a series of rises and falls in the oscillation signal Se. Therefore, in the described example, the data processing device 218 further includes a module 250 for decoding an encoded signal Sdr* present in another of these rises and falls of the measurement signal Sm. This encoded signal Sdr* includes data Rx from the same monitoring system 130 as the monitoring system 128.

[0104] In this way, monitoring systems 128 and 130 can exchange data.

[0105] Preferably, monitoring systems 128 and 130 will perform the same measurements (measuring current and / or measuring transmission line faults) equally and simultaneously at each end of the transmission line. Monitoring systems 128 and 130 can then communicate with each other, thereby transmitting the global redundancy status of the transmission line to the core members of the aircraft. If a difference exists between the two measurements, a system fault may be declared, and the system may be taken out of service and isolated from the rest of the power distribution system.

[0106] Still referencing Figure 2 The data processing device 218 includes a module 252 for analyzing the measurement signal Sm to detect degradation of the insulation 122 of the coaxial cable. This detection... Figure 2 The value is marked as parameter D3.

[0107] refer to Figure 8The portion of the measurement signal Sm, including the encoded signal Sdr*, typically has rising and falling edges generated from a square wave of the encoded signal Sdr*. Therefore, the rise time tm and fall time td of these rising and falling edges are very short. As the insulation 122 deteriorates, the rise time tm and fall time td will increase. For example, the statistical analysis module 248 can be designed to determine and track changes in the rise time tm and fall time td to infer the deterioration of the insulation 122 over time, in other words, cable aging, which affects the dielectric properties of the cable. In particular, it may increase high-frequency losses.

[0108] The accumulation of determined values ​​of rise time tm and fall time td during the lifespan of a coaxial cable will make it possible to track the aging of the cable and measure its aging rate.

[0109] The analysis module 252 can be designed to compare these rise times tm and fall times td with predefined thresholds, so that it would be reasonable to determine when to replace the transmission line 118 if the predefined thresholds are exceeded.

[0110] There are many reasons why cable insulation deteriorates, including high operating temperature.

[0111] Reference Figure 10 Another example of the implementation of monitoring system 128 will now be described. Monitoring system 130 can also adopt this design.

[0112] Figure 10 The monitoring system 128 in the middle is similar to Figure 2 The monitoring system in this embodiment connects the impedance Z between the first terminal of coil 216 and the electrical quality. Furthermore, in this embodiment, a voltage Vm is measured at the terminal of impedance Z. Therefore, the voltage Vm is proportional to the integral of the total magnetic flux Φ forming the internal signal, which essentially corresponds to a low-pass filter. This facilitates analog-to-digital conversion for converter 226, as the associated spectrum is naturally limited to low frequencies.

[0113] Obviously, the monitoring system according to the invention enables the measurement of the current in the transmission line and the detection of faults in the transmission line.

[0114] It should also be noted that the present invention is not limited to the exemplary embodiments described above. Various modifications, alternatives, or other variations that may be conceived by those skilled in the art are also included within the scope of the present invention.

[0115] For example, analysis modules 242 and 248 can use self-learning and artificial intelligence methods based on the acquired intrinsic data.

[0116] These modules can also be designed to receive and use other data, such as ambient temperature, pressure (or altitude) parameters, vibration levels, and any other parameters that may affect the normal operation of the monitored transmission line.

[0117] In the detailed description of the invention given above, the terminology used should not be construed as limiting the invention to the embodiments listed in this specification, but should be construed as including all equivalents that can be contemplated by those skilled in the art by applying their general knowledge to the implementation of the invention.

Claims

1. A system (128) for monitoring a transmission line (118) connected to the positive terminal (+) of a DC voltage source (102) via a positive connection (104) and connected to the negative terminal (-) of the DC voltage source (102) via a negative connection (106); the system comprising: A coupling device (210), connected to the positive terminal connection (104) but not to the negative terminal connection (106), is used to receive the current (I0) to be measured from the positive terminal (+) of the DC voltage source (102) transmitted by the transmission line (118); and —A data processing device (218), connected to the coupling device (210), and designed to: ● Provide an excitation signal (SE) to the coupling device (210) such that an internal signal (Φ) appears in the coupling device (210), the internal signal (Φ) having a deformation caused by the current to be measured (I0); ● Obtain a measurement signal (Sm) for measuring a variable (Vm) in the coupling device (210), wherein the signal (Sm) of the variable (Vm) is sensitive to the deformation of the internal signal (Φ); ●Based on the measured signal (Sm), a compensation signal (Sc) is provided to the coupling device (210) to counteract the deformation; and ●Evaluate the current to be measured (I0) based on the compensation signal (Sc); The feature is that the measurement signal (Sm) is also sensitive to faults present on the transmission line (118), and the data processing device (218) is also designed to analyze the measurement signal (Sm) and detect faults on the transmission line (118) based on the analysis.

2. The system of claim 1, wherein, The coupling device includes a transformer (212) having a ferromagnetic core (214), the internal signal being the total magnetic flux (Φ) present in the core (214), and the internal signal combining the excitation magnetic flux (ΦE) caused by the excitation signal (SE), the current magnetic flux (Φ0) caused by the current to be measured (I0), and the compensation magnetic flux (Φc) caused by the compensation signal (Sc) to substantially cancel out the current magnetic flux (Φ0).

3. The system of claim 1 or 2, wherein, The analysis of the measurement signal (Sm) includes: comparing the measurement signal (Sm) with at least one template (GB, GP), and wherein the fault on the transmission line (118) is detected starting from the moment when the measurement signal (Sm) is outside the at least one template (GB, GP).

4. The system of claim 1 or 2, wherein, The excitation signal (SE) includes an oscillation signal (Se).

5. The system of claim 4, wherein, The oscillation signal (Se) includes the sum of a sine wave at the fundamental frequency and a sine wave at the third harmonic, wherein the sine wave at the third harmonic is the sine wave at three times the fundamental frequency.

6. The system of claim 3, wherein, The excitation signal (SE) is generated by the coupling device (210) and transmitted on the transmission line (118). The data processing device (218) is also designed to encode the data to be transmitted (Tx) into an encoded signal (Sd), wherein the excitation signal (SE) includes the encoded signal (Sd) such that the transmitted signal includes the data to be transmitted (Tx).

7. The system of claim 6, wherein, The average value of the encoded signal (Sd) is zero.

8. The system according to claim 6, wherein, The fundamental frequency of the encoded signal (Sd) is higher than the fundamental frequency of the oscillation signal (Se).

9. The system according to claim 8, wherein, The at least one template includes a global template (GB), which, on the one hand, tracks the oscillation signal (Se) of the measurement signal (Sm) caused by the oscillation signal (Se) of the excitation signal (SE). On the other hand, it tracks the change of the measured signal (Sm) caused by the encoded signal (Sd) of the excitation signal (SE), and the encoded signal (Sde) of the measured signal (Sm). The envelope of ).

10. The system according to claim 8, wherein, The at least one template includes a local template (GP) that tracks the encoded signal (Sde) of the measurement signal (Sm) caused by the encoded signal (Sd) of the excitation signal (SE). (Changes).

11. The system according to claim 6, wherein, The oscillation signal (Se) comprises a series of rises and falls, wherein the encoded signal (Sd) appears only on one of the rises and falls.

12. The system according to claim 11, wherein, The measurement signal (Sm) includes a series of rises and falls, respectively corresponding to the series of rises and falls of the oscillation signal (Se), and wherein the data processing device (218) is also designed to decode the encoded signal appearing on another of the rises and falls of the measurement signal (Sm).

13. The system according to claim 1 or 2, wherein, The transmission line (118) is a coaxial cable.

14. A power distribution system (100), comprising: -power supply; —Electrical load; — A transmission line that connects the electrical load to the power source, so that the power source provides power to the electrical load; —A system for monitoring transmission lines according to any one of claims 1 to 13.

15. The power distribution system according to claim 14, wherein, The power source is a DC voltage source.

16. The power distribution system according to claim 15, wherein, The DC voltage source is greater than 100V.

17. An aircraft comprising a power distribution system according to any one of claims 14 to 16.

18. A method for monitoring a transmission line (118) connected to the positive terminal (+) of a DC voltage source (102) via a positive connection (104) and to the negative terminal (-) of the DC voltage source (102) via a negative connection (106), comprising a current sensor (202) including a coupling device (210) connected to the positive connection (104) but not to the negative connection (106) to receive a measured current (I0) transmitted by the transmission line (118) and originating from the positive terminal (+) of the DC voltage source (102), the method comprising: — Provide an excitation signal (SE) to the coupling device (210) such that an internal signal (Φ) appears in the coupling device (210), the internal signal (Φ) having a deformation caused by the current to be measured (I0); — Obtain a measurement signal (Sm) for measuring a variable (Vm) in the coupling device (210), wherein the signal (Sm) of the variable (Vm) is sensitive to the deformation of the internal signal (Φ); —Based on the measured signal (Sm), a compensation signal (Sc) is provided to the coupling device (210) to counteract the deformation; and —Evaluate the current to be measured (I0) based on the compensation signal (Sc); The method is characterized in that the measurement signal (Sm) is also sensitive to faults present on the transmission line (118), and the method further includes: analyzing the measurement signal (Sm) and detecting faults on the transmission line (118) based on the analysis.

19. A computer program that can be downloaded from a communication network and / or stored on a computer-readable medium, characterized in that, When the computer program is executed on a computer, the computer program includes instructions for performing the steps of the method according to claim 18.

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