Rail transit power supply cable high-low traveling wave measurement system
By combining a dual Rogowski coil electronic current transformer and a DSP control module, the problem that existing traveling wave monitoring devices cannot completely capture data in the initial stage of a fault is solved, achieving high-precision fault current signal acquisition and recovery, and improving the accuracy of fault location.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CHENGDU DINGHAN RAIL EQUIPMENT TECHNOLOGY CO LTD
- Filing Date
- 2025-04-18
- Publication Date
- 2026-05-12
AI Technical Summary
Existing traveling wave monitoring devices cannot fully capture transient information below the threshold during the initial stage of a fault in the acquisition of current signals from rail transit power supply cables, resulting in missing waveform data and affecting fault location accuracy and wave velocity calculation.
It employs dual Rogowski coil electronic current transformers and DSP control modules, combined with multiplexers, integrating circuits, A/D converters, and FIFO storage modules, to achieve accurate acquisition of current signals and complete recovery of fault current signals. Through channel switching and data splicing technology, complete fault current data is generated.
It improves measurement accuracy and anti-saturation capability, can fully acquire fault current information, provides more comprehensive and accurate data support, and has a measurement error of less than 5%.
Smart Images
Figure CN224231847U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of traveling wave measurement, specifically to a high and low traveling wave measurement system for rail transit power supply cables. Background Technology
[0002] The statements in this section are provided only as background information in connection with this disclosure and may not constitute prior art.
[0003] Existing traveling wave monitoring devices typically employ a threshold-triggered data acquisition mechanism for acquiring current signals from power supply cables in rail transit. When a fault occurs in the transmission line, the traveling wave current amplitude must reach a preset trigger threshold before the device will initiate high-speed sampling and store the fault data.
[0004] However, this triggering mechanism has inherent flaws:
[0005] In the initial stage of a fault, the amplitude of the traveling wave current increases exponentially from zero. When the trigger threshold is reached, the device can only record the current waveform above the threshold. The transient process information below the threshold in the initial stage of the fault is completely lost because it does not enter the sampling and storage stage. This data truncation phenomenon results in the missing key characteristic parameters of the initial traveling wave head in the recorded fault waveform, especially the inability to fully capture transient characteristics that reflect the fault type, such as the traveling wave front steepness and initial phase.
[0006] Therefore, under the requirement of high-precision fault location in rail transit power supply systems, the lack of waveform data generated by existing technologies will directly affect the accuracy of traveling wave velocity calculation, resulting in increased fault ranging error. Furthermore, it is difficult to reconstruct the complete fault transient process waveform through existing sampling mechanisms, which has become the main bottleneck restricting the improvement of traveling wave ranging technology. Utility Model Content
[0007] The purpose of this invention is to provide a high and low traveling wave measurement system for rail transit power supply cables, which addresses the problems existing in the prior art.
[0008] The technical solution of this utility model is as follows:
[0009] A system for measuring the high and low traveling waves of rail transit power supply cables includes:
[0010] The signal sampling module includes a first Rogowski coil electronic current transformer and a second Rogowski coil electronic current transformer. The measurement accuracy of the first Rogowski coil electronic current transformer is higher than that of the second Rogowski coil electronic current transformer, and the anti-saturation capability of the second Rogowski coil electronic current transformer is stronger than that of the first Rogowski coil electronic current transformer.
[0011] The multiplexer module connects to the output terminals of the first and second Rogowski coil electronic current transformers and receives the channel selection signal from the DSP control module to achieve channel switching.
[0012] The integrating circuit module performs integration and conversion on the voltage signal output by the multiplexer module;
[0013] The A / D conversion module converts the integrated analog signal into a digital signal, and its output is connected to the FIFO storage module and the current comparison module, respectively.
[0014] The current comparison module compares the data converted by the A / D conversion module with a preset threshold.
[0015] The DSP control module can set preset thresholds, send corresponding channel selection signals based on the comparison results of the current comparison module, and read, store, and splice data in the FIFO storage module to restore complete fault current information.
[0016] Furthermore, the first Rogowski coil electronic current transformer is used to acquire the current signal for measurement.
[0017] Furthermore, a second Rogowski coil electronic current transformer is used to acquire fault current signals.
[0018] Furthermore, the multiplexer module uses a multiplexer analog switch CD4067 to determine which current transformer output is activated based on the channel selection signal from the DSP control module.
[0019] Furthermore, the A / D conversion module is clocked by the DSP control module to control the sampling frequency.
[0020] Furthermore, once the FIFO storage module is fully loaded, it sends an interrupt signal to the DSP control module.
[0021] Furthermore, the current comparison module is a 16-bit comparator composed of five 74HC85 four-bit numerical comparators connected in parallel. It receives the data converted by the A / D conversion module and compares it with the threshold set by the DSP control module.
[0022] Furthermore, the workflow of the DSP control module includes:
[0023] Step S1: Initialize the measurement channel to the first Rogowski coil electronic current transformer;
[0024] Step S2: Real-time monitoring of the current comparison module output;
[0025] Step S3: When the detected current value exceeds the threshold, a channel switching command is issued;
[0026] Step S4: Control the multiplexer to switch to the second Rogowski coil electronic current transformer;
[0027] Step S5: Read the measurement data stored before the switch from the FIFO storage module;
[0028] Step S6: Combine the measurement data before and after the switch.
[0029] Furthermore, the splicing in step S6 is based on timestamps.
[0030] Furthermore, the splicing includes:
[0031] An interpolation algorithm is used to fit the data at the switching time point to form complete fault current data.
[0032] Compared with existing technologies, the beneficial effects of this utility model are:
[0033] This invention achieves precise acquisition of measurement current signals and fault current signals. Utilizing dual current transformer switching and a FIFO storage module, it improves measurement accuracy and anti-saturation capability, enabling complete acquisition of fault current information and providing more comprehensive and accurate data support for subsequent traveling wave analysis. Testing showed that the errors in all indicators for measuring 8 / 20μs impulse current and 30 / 60μs operating impulse current were less than 5%. Attached Figure Description
[0034] Figure 1 This is a block diagram illustrating the principle of a high and low traveling wave measurement system for rail transit power supply cables. Detailed Implementation
[0035] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.
[0036] Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0037] The features and performance of this utility model will be further described in detail below with reference to the embodiments.
[0038] Example 1
[0039] Please see Figure 1 A system for measuring the high and low traveling waves of rail transit power supply cables, comprising:
[0040] The signal sampling module includes:
[0041] The first Rogowski coil electronic current transformer and the second Rogowski coil electronic current transformer have higher measurement accuracy than the second Rogowski coil electronic current transformer, and the second Rogowski coil electronic current transformer has stronger anti-saturation capability than the first Rogowski coil electronic current transformer.
[0042] The multiplexer module connects to the output terminals of the first and second Rogowski coil electronic current transformers and receives the channel selection signal from the DSP control module to achieve channel switching.
[0043] The integrating circuit module performs integration and conversion on the voltage signal output by the multiplexer module;
[0044] The A / D conversion module converts the integrated analog signal into a digital signal, and its output is connected to the FIFO storage module and the current comparison module respectively; that is, on the one hand, the signal is sent to the FIFO storage module for buffering and temporary storage, and on the other hand, it is sent to the current comparison module for comparison.
[0045] The current comparison module compares the data converted by the A / D conversion module with a preset threshold. When the measured current signal is greater than the threshold, the current comparator output interrupts the DSP control module, which then controls the multiplexer to switch channels.
[0046] The DSP control module can set preset thresholds, send corresponding channel selection signals based on the comparison results of the current comparison module, and read, store, and splice data in the FIFO storage module to restore complete fault current information.
[0047] In this embodiment, specifically, the first Rogowski coil electronic current transformer is used to acquire the current signal for measurement;
[0048] The second Rogowski coil electronic current transformer is used to collect fault current signals;
[0049] One device has high measurement accuracy but weak anti-saturation capability and is used to acquire current signals for measurement; the other device has poor accuracy but strong anti-saturation capability and is used to acquire fault current signals.
[0050] In this embodiment, specifically, the multiplexer module uses a multiplexer analog switch CD4067, which determines which current transformer output to connect based on the channel selection signal of the DSP control module.
[0051] In this embodiment, the A / D conversion module is specifically provided with a clock signal by the DSP control module to control the sampling frequency.
[0052] In this embodiment, specifically, the FIFO storage module sends an interrupt signal to the DSP control module after it is fully loaded.
[0053] In this embodiment, specifically, the current comparison module is a 16-bit comparator composed of five 74HC85 four-bit numerical comparators connected in parallel. It receives the data converted by the A / D conversion module and compares it with the threshold set by the DSP control module.
[0054] In this embodiment, the specific workflow of the DSP control module includes:
[0055] Step S1: Initialize the measurement channel to the first Rogowski coil electronic current transformer;
[0056] Step S2: Real-time monitoring of the current comparison module output;
[0057] Step S3: When the detected current value exceeds the threshold, a channel switching command is issued;
[0058] Step S4: Control the multiplexer to switch to the second Rogowski coil electronic current transformer;
[0059] Step S5: Read the measurement data stored before the switch from the FIFO storage module;
[0060] Step S6: Combine the measurement data before and after the switch.
[0061] In this embodiment, specifically, the splicing in step S6 is based on timestamps.
[0062] In this embodiment, specifically, the splicing includes:
[0063] An interpolation algorithm is used to fit the data at the switching time point to form complete fault current data.
[0064] In this embodiment, it should be noted that the specific operations of splicing the parts are things that can be done by those skilled in the art without any innovation. The above is only one implementation form, including but not limited to this form.
[0065] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.
[0066] The background section is provided to generally present the context of this utility model. The work of the currently named inventors, the work to the extent described in this background section, and aspects described in this section that did not constitute prior art at the time of filing are neither expressly nor impliedly acknowledged as prior art to this utility model.
Claims
1. A system for measuring the high and low traveling waves of rail transit power supply cables, characterized in that, include: The signal sampling module includes a first Rogowski coil electronic current transformer and a second Rogowski coil electronic current transformer. The measurement accuracy of the first Rogowski coil electronic current transformer is higher than that of the second Rogowski coil electronic current transformer, and the anti-saturation capability of the second Rogowski coil electronic current transformer is stronger than that of the first Rogowski coil electronic current transformer. The multiplexer module connects to the output terminals of the first and second Rogowski coil electronic current transformers and receives the channel selection signal from the DSP control module to achieve channel switching. The integrating circuit module performs integration and conversion on the voltage signal output by the multiplexer module; The A / D conversion module converts the integrated analog signal into a digital signal, and its output is connected to the FIFO storage module and the current comparison module, respectively. The current comparison module compares the data converted by the A / D conversion module with a preset threshold. The DSP control module can set preset thresholds, send corresponding channel selection signals based on the comparison results of the current comparison module, and read, store, and splice data in the FIFO storage module to restore complete fault current information.
2. The high and low traveling wave measurement system for rail transit power supply cables according to claim 1, characterized in that, The first Rogowski coil electronic current transformer is used to acquire current signals for measurement.
3. The high and low traveling wave measurement system for rail transit power supply cables according to claim 2, characterized in that, The second Rogowski coil electronic current transformer is used to collect fault current signals.
4. The high and low traveling wave measurement system for rail transit power supply cables according to claim 1, characterized in that, The multiplexer module uses a CD4067 multiplexer analog switch, which determines which current transformer output to connect based on the channel selection signal from the DSP control module.
5. A high / low traveling wave measurement system for rail transit power supply cables according to claim 1, characterized in that, The A / D conversion module is powered by a clock signal provided by the DSP control module, which controls the sampling frequency.
6. A high / low traveling wave measurement system for rail transit power supply cables according to claim 1, characterized in that, When the FIFO storage module is full, it sends an interrupt signal to the DSP control module.
7. A high / low traveling wave measurement system for rail transit power supply cables according to claim 1, characterized in that, The current comparison module is a 16-bit comparator composed of five 74HC85 four-bit numerical comparators connected in parallel. It receives the data converted by the A / D conversion module and compares it with the threshold set by the DSP control module.