Method for measuring closing angle of main circuit breaker of motor train unit train

Abstract

The invention discloses a method for measuring a closing angle of a main circuit breaker of a motor train unit train, which belongs to the technical field of rail transit electrical, and comprises the following steps: S10, sampling waveforms of a voltage signal and a current signal of a pantograph of the motor train unit by adopting a preset sampling frequency, each sampling point is ensured to have a preset resolution; s20, positioning the maximum peak point of the impact current waveform in the sampled current data, and taking the peak point as an initial position; s30, starting from the impact current peak point, counting a preset number of data points backwards to reach a preset angle position; s40, in the data range after the preset angle position is reached, first current burr data are found through current value comparison; s50, calculating the actual closing angle of the main circuit breaker; the method has the advantages that the measurement precision and reliability are effectively improved, and important technical support is provided for safe operation and fault diagnosis of the motor train unit train.

Description

Technical Field

[0001] This invention relates to the field of rail transit electrical technology, and more specifically, to a method for measuring the closing angle of the main circuit breaker of a high-speed train. Background Technology

[0002] my country's electrified railways widely adopt single-phase AC power supply. To balance the three-phase power load, electrical phase separation facilities are installed in the overhead contact system. The existence of electrical phase separation is a necessary design feature of electrified railway power supply systems, used to isolate the power supply from adjacent substations or adjacent power supply sections. During high-speed train operation, trains frequently pass through different power supply sections, and the overhead contact system power supply switches from one substation to another approximately every 20 to 50 kilometers. Between the overhead contact system sections where power supplies from two substations intersect, a de-energized zone is set up to ensure electrical isolation between different power supply phases and system safety. This design avoids direct short circuits between adjacent power supply phases, ensuring the stable operation of the power supply system.

[0003] Before entering the electrical phase-separation zone, the main circuit breaker (VCB) of a high-speed train must be opened in advance to disconnect the power supply to the train and allow it to coast through the de-energized area. After passing through the electrical phase-separation zone, the main circuit breaker must be closed again to restore power and allow the train to operate normally. The opening and closing of the main circuit breaker are necessary and frequent operations performed by the high-speed train during operation, especially on trains running long-distance lines, where these operations may be repeated multiple times. When the main circuit breaker closes, a closing inrush current is generated, caused by the voltage waveform at the moment the contacts close and the inductive load. The magnitude of the closing inrush current is closely related to the closing angle, which refers to the angle of the voltage waveform at the moment the main circuit breaker contacts close. The closing inrush current reaches its maximum value when the closing angle is 0°, and its minimum value when the closing angle is 90°. Therefore, if the actual closing angle of the main circuit breaker can be accurately measured and the measurement results fed back to the EMU control system, thereby adjusting the closing action of the main circuit breaker, the closing inrush current can be effectively reduced. This not only protects the main circuit breaker and its related equipment from damage caused by high current surges, but also extends the service life of the equipment and improves the stability and safety of EMU operation.

[0004] However, in practical applications, measuring the closing angle of main circuit breakers faces significant technical challenges. Traditional methods generally rely on voltage waveform detection to determine the closing angle at the moment the contacts close. However, this method has several limitations. First, during the closing operation, the voltage waveform may be distorted, spiked, or interfered with due to interference from electrical equipment or the external electromagnetic environment, leading to a decrease in the accuracy of the voltage waveform signal. Second, because the change in the voltage waveform at the moment of closing may be small, it is difficult to effectively capture the accurate closing moment, resulting in significant errors in the detection results. Furthermore, in complex operating environments, the voltage waveform may be affected by noise interference, making it difficult for voltage waveform-based closing angle detection methods to meet the high-precision requirements of practical applications. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, a method for measuring the closing angle of the main circuit breaker of a high-speed train is proposed. This method effectively improves the measurement accuracy and reliability, and provides important technical support for the safe operation and fault diagnosis of high-speed trains.

[0006] The technical solution adopted by the invention to solve its technical problem is: a method for measuring the closing angle of the main circuit breaker of a high-speed train, the improvement of which includes:

[0007] S10: The voltage and current signal waveforms of the pantograph of the EMU are sampled using a preset sampling frequency, with a preset number of points sampled per cycle to ensure that each sampling point has a preset resolution.

[0008] S20: Locate the maximum peak point of the impact current waveform in the sampled current data and use this peak point as the starting position;

[0009] S30: Starting from the peak point of the impact current, count a preset number of data points backward to reach a preset angular position;

[0010] S40: Within the data range after reaching the preset angle position, find the first current glitch data by comparing the current values;

[0011] S50: Calculate the actual closing angle of the main circuit breaker.

[0012] Furthermore, in step S10, the voltage signal is isolated and converted by a voltage transformer, and then amplified by an operational amplifier before being input to the A / D sampling chip.

[0013] Furthermore, in step S10, the current signal is isolated and converted by a current transformer, and then amplified by an operational amplifier before being input to the A / D sampling chip.

[0014] Furthermore, in step S10, the A / D sampling chip is set to sample the voltage signal and the current signal at a sampling frequency of 180kHz, with 3600 data points sampled per cycle, and each data point corresponding to a resolution of 0.1°.

[0015] Furthermore, in step S10, the peak point of the impact current reaches a preset angle of 180°.

[0016] Furthermore, in step S40, the current spike point is the first abnormal change point in the current waveform that appears in the impact current waveform.

[0017] Furthermore, in step S50, the closing angle is calculated using the following formula:

[0018] Closing angle = 180° - (A+1) / 10;

[0019] Where A is the number of sampling data points from the maximum peak point of the impact current waveform to the current spike point.

[0020] The beneficial effects of this invention are: the method effectively improves measurement accuracy and reliability, providing important technical support for the safe operation and fault diagnosis of high-speed trains. Attached Figure Description

[0021] Figure 1 This is a flowchart of a method for measuring the closing angle of the main circuit breaker of a high-speed train according to the present invention;

[0022] Figure 2 This is a voltage signal waveform diagram of a method for measuring the closing angle of the main circuit breaker of a high-speed train according to the present invention.

[0023] Figure 3 This is a current signal waveform diagram of a method for measuring the closing angle of the main circuit breaker of a high-speed train according to the present invention. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0026] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0027] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Secondly, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0028] This method involves high-resolution sampling of voltage and current signals at a preset sampling frequency, locating the peak point of the inrush current as the starting position, and identifying the first current spike data after a preset angle position, thereby accurately calculating the closing angle. This method effectively improves measurement accuracy and reliability, providing crucial technical support for the safe operation and fault diagnosis of high-speed trains.

[0029] See Figure 1 As shown, the present invention provides a method for measuring the closing angle of the main circuit breaker of a high-speed train, including:

[0030] S10: The voltage and current signal waveforms of the pantograph of the EMU are sampled using a preset sampling frequency, with a preset number of points sampled per cycle to ensure that each sampling point has a preset resolution.

[0031] S20: Locate the maximum peak point of the impact current waveform in the sampled current data and use this peak point as the starting position;

[0032] S30: Starting from the peak point of the impact current, count a preset number of data points backward to reach a preset angular position;

[0033] S40: Within the data range after reaching the preset angle position, find the first current glitch data by comparing the current values;

[0034] S50: Calculate the actual closing angle of the main circuit breaker.

[0035] Through high-resolution sampling and precise data processing, the peak value and current spike point of the inrush current can be accurately located, ensuring the accuracy of the actual closing angle calculation.

[0036] In this method, the signal waveform data is first accurately acquired, with a preset number of sampling points per cycle to ensure sufficient resolution and accuracy. High-resolution sampling allows for the reconstruction of detailed features of voltage and current signals, providing high-quality data for subsequent analysis. The maximum peak point of the inrush current is identified to determine the starting position of the current waveform. The peak value of the inrush current is a key physical phenomenon during the closing of the main circuit breaker, reflecting its triggering behavior. Based on the peak value of the inrush current, the target angle position is precisely located by shifting the time sequence forward using a preset number of data points. Combining the relationship between sampling frequency and the number of points, the phase angle of the waveform can be calculated, thereby determining the specific angle range corresponding to the closing position. "Current spikes" are searched within a preset range. These current spikes are brief high-frequency current fluctuations generated after the main circuit breaker is triggered, a key characteristic point in the closing process. Based on the current peak point, current spike point, and signal time sequence from the previous steps, the actual closing angle of the circuit breaker is calculated. The closing angle is an important indicator of the main circuit breaker's performance, reflecting its operational behavior in the power grid phase.

[0037] Furthermore, the voltage and current signals of the pantograph of the EMU are sampled at a preset sampling frequency. A fixed number of points are sampled per cycle to ensure that the sampled data has a certain resolution and accuracy. This ensures the integrity of the signal sampling and the time-domain accuracy of the data, providing data for subsequent signal analysis and feature extraction. The voltage transformer is a device used in power systems to measure high voltage. It converts high voltage into a standard low voltage so that measuring instruments and protection devices can measure and use it safely and accurately. The voltage transformer isolates the high-voltage system from measuring instruments and protection devices, ensuring the safety of personnel and equipment. The current transformer is a device used to measure high current. It converts high current into a standard low current so that measuring instruments and protection devices can measure and use it safely and accurately. The working principle of the current transformer is based on electromagnetic induction, similar to a transformer, but its main purpose is current conversion rather than voltage conversion.

[0038] In step S10, the voltage signal is isolated and converted by a voltage transformer, amplified by an operational amplifier, and then input to the A / D sampling chip. The voltage transformer isolates the high-voltage signal from the low-voltage sampling circuit, effectively preventing high voltage from damaging the operational amplifier and A / D sampling chip, ensuring the safety of equipment and personnel. While converting the signal, the voltage transformer preserves the frequency characteristics of the voltage signal, ensuring the accuracy of the waveform features and aiding subsequent analysis and calculation. The operational amplifier has strong anti-interference capabilities, suppressing electromagnetic noise and other interference signals mixed into the voltage signal, improving signal quality. The operational amplifier amplifies the low-amplitude signal output from the voltage transformer, making its amplitude more suitable for the input range of the A / D sampling chip, thereby improving the resolution and accuracy of A / D sampling. The operational amplifier maintains linear signal amplification, without changing the waveform, frequency, or phase of the voltage waveform, providing an accurate original signal for subsequent A / D sampling and calculation. Similarly, in step S10, the current signal is isolated and converted by a current transformer, amplified by an operational amplifier, and then input to the A / D sampling chip. An A / D sampling chip, or analog-to-digital converter (ADC), is an electronic component that converts continuously changing analog signals into discrete digital signals. It plays a crucial role in electronic devices, especially in applications requiring the conversion of physical quantities into digital signals for processing by digital systems.

[0039] In this embodiment, 4. Each cycle is 20ms, and the 180K / S conversion calculation is 3600 / 20ms, meaning there are 3600 sampled data points per cycle. This translates to 3600 waveform data points for a complete sine wave (positive and negative 360°), with each data sampling time interval being exactly 0.1°. The A / D sampling chip is configured to sample the voltage and current signals at a sampling frequency of 180kHz, sampling 3600 data points per cycle, with each data point corresponding to a resolution of 0.1°. The 180kHz sampling frequency can capture signal frequencies up to 90kHz, meeting the sampling requirements for high-order harmonics in power frequency systems. For high-order harmonics of a standard 50Hz power frequency signal, this sampling setting can easily capture higher harmonic components. With 3600 data points per cycle and a sampling period of 5.56μs (1 / 180kHz), it can reflect the dynamic changes of voltage and current waveforms in real time. It can accurately capture transient waveforms under conditions of signal fluctuations, short-term abrupt changes, and frequency shifts. With 3600 data points per cycle, the waveform can be subdivided, resulting in a better reproduction of the actual waveform compared to systems with lower sampling rates. Synchronous sampling of voltage and current signals can be used to analyze the phase relationship between them. The high sampling resolution of 0.1° angular resolution enables precise measurement of phase difference, ensuring more accurate synchronous detection in power systems.

[0040] In step S10, the peak value of the inrush current reaches a preset angle of 180°. In the power frequency waveform, the voltage corresponding to 180° is near the zero intersection point, at which time the instantaneous voltage value of the power grid is close to zero. Setting the peak value of the inrush current at this moment can significantly reduce the voltage fluctuations of the power grid and the impact of the inrush on the system.

[0041] Furthermore, refer to Figures 2-3 As shown, through analysis of numerous closing waveforms, the peak inrush current when the main circuit breaker on the EMU closes will inevitably correspond to the 180° position of the voltage. At the moment of closing, a current change (current spike) will appear on the current waveform. Therefore, the voltage angle at closing can be calculated by measuring the current waveform. In step S50, the closing angle is calculated using the following formula:

[0042] Closing angle = 180° - (A+1) / 10;

[0043] Where A is the number of sampling data points from the maximum peak point of the impact current waveform to the current spike point.

[0044] The (A+1) in the above formula takes into account the starting position of the sampling point (peak point). The +1 here is to make the calculation result accurate to the position of the glitch point. The actual closing angle of the main circuit breaker of the EMU can be calculated quickly and accurately through the formula.

[0045] In this invention, high-resolution sampling of voltage and current signals is performed using a preset sampling frequency. The peak point of the inrush current is located as the starting position, and the first current spike data is identified after a preset angle position, thereby accurately calculating the closing angle. This method effectively improves measurement accuracy and reliability, providing important technical support for the safe operation and fault diagnosis of high-speed trains.

[0046] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

[0047] Finally, it should be noted that the above is a detailed description of the preferred embodiments of the present invention, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for measuring the closing angle of a main circuit breaker of an EMU train, characterized in that: include: S10: sampling the voltage signal and current signal waveform of the pantograph of the EMU using a preset sampling frequency, wherein a preset number of points are sampled per cycle to ensure that each sampling point has a preset resolution; S20: locating the maximum peak point of the impulse current waveform in the sampled current data, and taking the peak point as the starting position; S30: starting from the peak point of the impulse current, counting a preset number of data points backward to reach a preset angle position; S40: Finding the first current burr data by comparing the current values ​​within the data range after reaching the preset angle position; S50: Calculate the actual closing angle of the main circuit breaker.

2. A method for measuring the closing angle of a main circuit breaker of an EMU train according to claim 1, characterized in that: In step S10, the voltage signal is isolated and converted by a voltage transformer, amplified by an operational amplifier, and then input into an A / D sampling chip.

3. The method for measuring the closing angle of the main circuit breaker of an EMU train according to claim 1, characterized in that: In step S10, the current signal is isolated and converted by a current transformer, amplified by an operational amplifier, and then input into an A / D sampling chip.

4. The method for measuring the closing angle of the main circuit breaker of an EMU train according to claim 1, characterized in that: In step S10, the A / D sampling chip is set to sample the voltage signal and the current signal at a sampling frequency of 180 kHz, 3600 data points are sampled per cycle, and each data point corresponds to a resolution of 0.1°.

5. The method for measuring the closing angle of the main circuit breaker of an EMU train according to claim 1, characterized in that: In step S10, the peak point of the impact current reaches a preset angle of 180°.

6. The method for measuring the closing angle of the main circuit breaker of an EMU train according to claim 1, characterized in that: In the step S40, the current burr point is the current abnormal change point that first appears in the impulse current waveform.

7. The method for measuring the closing angle of the main circuit breaker of an EMU train according to claim 1, characterized in that: In step S50, the closing angle is calculated by the following formula: Closing angle = 180°-(A+1) / 10; Wherein, A is the number of sampling data points from the maximum peak point of the impulse current waveform to the current burr point.

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