Electric vehicle charging pile metering performance and output quality remote detection method

Abstract

The invention discloses an electric vehicle charging pile metering performance and output quality remote detection method. Aiming at the technical problems of low field manual verification efficiency, incapability of covering a high-power direct-current quick charging pile, lack of online electric energy quality and safety early warning and the like of an existing charging pile, multi-source data such as voltage and current of the charging pile and a vehicle BMS message are collected on line through a verification tester, and electric energy accumulation is realized through high-frequency sampling and integral operation; completing metering error evaluation by using a comparison algorithm; obtaining an electric energy quality index by means of discrete Fourier transform and ripple analysis; and various detection results are uploaded to a platform in real time through a wireless network for comprehensive analysis, health scoring and fault early warning. The device does not need to be shut down, is unattended, is suitable for various pile types of alternating current slow charging and direct current quick charging, is high in precision, is low in cost, is easy to popularize, is good in reusability, can remarkably improve the verification efficiency of the charging pile, and guarantees the metering accuracy and operation safety.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle charging facility testing technology, specifically a remote testing method for the metering performance and output quality of electric vehicle charging piles. Background Technology

[0002] With the large-scale promotion of new energy vehicles, public charging piles and dedicated charging facilities are rapidly being deployed in urban roads, highway service areas, and other scenarios, and are gradually being integrated into urban energy management and IoT platforms to achieve remote monitoring and intelligent scheduling of the charging process. This networked deployment not only meets the ever-increasing charging demand but also provides massive data support for energy load optimization and coordinated management of traffic and electricity. However, as a key node in metering and power quality, the long-term stable operation and measurement accuracy of charging piles place higher demands on fair pricing and electricity safety. If there are no effective means to ensure that the metering devices of charging piles continue to work accurately in a large-scale network, the settlement errors and trust risks between users and operators will increase accordingly.

[0003] Currently, mainstream methods for metering and quality inspection of charging piles have significant shortcomings. On the one hand, manual on-site verification relies on inspectors carrying heavy equipment such as standard energy meters and load boxes to conduct comparative tests on each AC ≤250A or DC charging pile. This process is not only time-consuming and labor-intensive, but also difficult to meet the on-site testing requirements of super-fast charging piles up to 600A. On the other hand, while pre-installing online monitoring modules inside the charging piles can acquire data such as voltage and current in real time, it significantly increases equipment costs, and the newly added modules themselves require regular on-site calibration, failing to fundamentally solve the problems of manpower and complexity in operation and maintenance. Meanwhile, although the operation platform can detect operational anomalies by remotely reading the metering and status data of the charging piles, the lack of independent reference makes it difficult to determine whether the equipment's metering device has drifted or whether the output quality meets the standards.

[0004] Regarding power quality, most charging stations currently do not integrate dedicated power quality monitoring modules, making it difficult to extend laboratory-scale ripple, harmonic, and frequency stability testing to online operations. Overshoot, voltage drops, or high-order harmonics in the charging current not only affect battery charging efficiency but can also damage battery life and onboard electronic devices, yet these issues are often only detected passively after user complaints or equipment malfunctions occur.

[0005] Furthermore, the typical early fault signal of overheating at the charging gun interface is not effectively captured by traditional protection mechanisms. Protection is only triggered when the temperature rises sharply and damages the components, posing a high safety hazard. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a remote detection method for the metering performance and output quality of electric vehicle charging piles, so as to realize multi-dimensional real-time evaluation and early warning of the metering performance, power quality and safety status of charging piles, without the need for shutdown or manual on-site verification, thereby greatly improving verification efficiency, reducing operation and maintenance costs, and ensuring metering accuracy and charging safety.

[0007] Therefore, the present invention adopts the following technical solution: a remote detection method for the metering performance and output quality of electric vehicle charging piles, comprising:

[0008] Step 1: Connect the verification tester used for remote measurement to the output circuit of the electric vehicle charging pile to be verified, and complete the connection between the charging pile and the electric vehicle; start the verification tester and establish a data communication link with the charging pile operation management platform through its built-in communication module (such as 4G / 5G wireless network) to ensure that the subsequent test data can be transmitted to the charging pile operation management platform in real time for monitoring and analysis;

[0009] This step ensures that the testing environment is ready and that the calibration tester and the charging pile operation management platform are simultaneously ready to go.

[0010] Step 2: Trigger an actual charging process and use a calibration tester to monitor the output of the charging pile throughout the process. Obtain the metering information of the charging pile under actual working conditions. The charging power accumulated by the calibration tester is used as the standard charging power.

[0011] Step 3: After charging is completed, the calibration and testing instrument uploads the standard charging amount obtained in Step 2 to the charging pile operation and management platform; the charging pile operation and management platform obtains the charging amount recorded by the corresponding charging pile billing system according to the charging start and end time, and calculates the measurement error of the charging pile's built-in metering device based on the charging amount and the standard charging amount.

[0012] The measurement error results obtained in this step will serve as the basis for remote verification of the metering performance of charging piles.

[0013] Step 4: During the charging process and under steady-state conditions, monitor and analyze the output voltage of the charging pile to obtain the deviation index of the output voltage and evaluate the fluctuation / stability of the output voltage.

[0014] This step yields the accuracy and stability indicators of the charging pile's output voltage, laying the foundation for evaluating the quality of the output power.

[0015] Step 5: Use a calibration tester to monitor the dynamic response characteristics of the charging pile's output current and obtain the dynamic response index of the charging pile's output current control.

[0016] Step 6: For AC charging piles, the calibration tester performs harmonic analysis on the output voltage and current waveforms, calculates the harmonic distortion (THD), and obtains the AC harmonic index of the charging pile's AC output.

[0017] This step obtains the harmonic distortion index of the AC output of the charging pile and evaluates its power quality compliance.

[0018] Step 7: For DC charging piles, the calibration tester detects and analyzes the ripple component in the output voltage to obtain the DC ripple index of the DC output voltage of the charging pile.

[0019] This step yields the ripple index of the charging pile's DC output voltage, which is used to measure the quality of DC power.

[0020] Step 8: After completing the above tests, the calibration instrument summarizes and organizes the data on metering performance, voltage quality, current dynamic response, and power quality during the charging process, and generates a complete test result for remote online testing.

[0021] Furthermore, in step two, by parsing the charging communication messages between the electric vehicle and the charging pile, the start and end times of charging are identified to determine the energy measurement cycle. During the charging process, the calibration tester collects the voltage and current signals output by the charging pile in real time, and accumulates and integrates the instantaneous power to obtain the total charging capacity of the entire charging process. At the same time, it records key parameters during the charging process (such as the maximum voltage, current value and their occurrence time) to provide basic data for subsequent analysis.

[0022] Furthermore, in step three, the measurement error δ Q Calculate using the following formula:

[0023]

[0024] Among them, Q m The charging capacity of the charging station, Q s Standard charging capacity;

[0025] The measurement error δ Q Compared with the specified error limit, if δ Q If the deviation is within the allowable range, it indicates that the metering performance of the charging pile is qualified; if it exceeds the allowable range, it is determined that the metering of the charging pile is inaccurate.

[0026] Furthermore, in step four, if it is an AC charging pile, the calibration tester measures the effective value and frequency of the output voltage and evaluates the voltage amplitude deviation and frequency deviation; if it is a DC charging pile, the average value of the output voltage is measured and compared with its set value or rated value to evaluate the voltage regulation accuracy.

[0027] Furthermore, in step four, the output voltage deviation is expressed as a relative error δ. V The calculation formula is as follows:

[0028]

[0029] Among them, V out This is the average value of the output voltage measured by the calibration tester; the effective value is given under AC conditions, and the steady-state voltage is given under DC conditions; V nom The rated output voltage or current setting value of the charging pile is determined by δ. V The output voltage deviation is obtained; if the output voltage deviation exceeds the preset threshold, it is considered that there is a problem with the quality of the charging pile's output voltage.

[0030] Furthermore, in step four, the testing instrument evaluates the voltage stability based on the collected data; if abnormal voltage fluctuations are detected (such as overshoot or drop exceeding standard requirements), it is considered that there is a problem with the quality of the charging pile's output voltage.

[0031] Furthermore, in step five, when the charging current changes abruptly (e.g., the vehicle BMS requests a rapid change in current or the charging process switches from constant voltage to constant current), the current change curve over time is recorded, and the response speed of the current rise or fall and whether there is an overshoot phenomenon are analyzed.

[0032] Define the current overshoot percentage σ I The formula used to quantify the degree of current overshoot is as follows:

[0033]

[0034] Among them, I max I represents the peak current that occurs during the current response process. steady The steady-state target current value (i.e., the current set and to be maintained by the charging pile); by calculating σ I The percentage overshoot of the current relative to the steady-state target current value is obtained, and the current response time t is measured simultaneously. r (defining t) r The time required for the current to reach 95% of its steady-state value from the start of a change is used to measure the response speed; the calibration tester obtains the waveform characteristics of the current response based on the collected data to judge the quality of the charging pile's current control: if σ I Too large or t r An excessively long current length indicates poor current control by the charging station under varying loads, potentially impacting battery charging safety. Ideally, σ... I It should be close to 0 and t r Short enough.

[0035] Furthermore, in step six, the total harmonic distortion (THD) quantitatively reflects the degree of waveform distortion, and its calculation formula is as follows:

[0036]

[0037] Where U1 is the effective value of the fundamental component, U n Let N be the effective value of the nth harmonic component, where n ≥ 2, and N is the highest harmonic order.

[0038] According to relevant standards, harmonics are typically calculated to N=40 or higher. The voltage harmonic distortion rate and current harmonic distortion rate of the charging pile output voltage are calculated using formula (4). The calibration tester compares the measured amplitude of each harmonic with the fundamental wave to obtain the THD value, and compares it with the relevant power quality standard limits (e.g., the THD of the public power grid voltage should be less than 5%). If the THD of the charging pile output voltage or current exceeds the standard requirements, it indicates that its output waveform is severely distorted, which may cause additional losses or interference to electrical equipment (such as electric vehicle on-board chargers).

[0039] Furthermore, in step seven, the ripple index is characterized by the ripple coefficient, which is defined as the percentage of the peak-to-peak output voltage relative to the average DC value. The calculation formula is as follows:

[0040]

[0041] Among them, V max V represents the maximum instantaneous value of the DC output voltage during the switching cycle. min V is the minimum instantaneous value within the switching cycle. dc This is the average value (or DC component) of the DC output voltage;

[0042] The RF calculated using the above formula reflects the magnitude of the ripple voltage in the DC output relative to the average value. The calibration tester can obtain V using a method combining time-domain sampling and frequency-domain analysis. max V min For example, a Discrete Fourier Transform (FFT) is performed on the acquired voltage waveform to extract the amplitude information of each frequency component, such as the power frequency and switching frequency. The high-frequency components correspond to the ripple voltage. The calculated RF value is compared with relevant standard limits (such as the ripple coefficient needing to be lower than a specified percentage) to evaluate the purity of the DC output voltage. A large RF value indicates excessive ripple (AC interference) components in the DC output, which may lead to reduced efficiency of the charging equipment or excessive heat generation; a smaller RF value indicates a more stable and pure output voltage.

[0043] Furthermore, in step eight, the charging pile operation management platform compares each measured indicator with a pre-set qualified threshold: if all power quality indicators (such as metering error, output voltage deviation, dynamic response indicators, harmonic distortion, ripple coefficient, etc.) are within the qualified threshold range, the charging pile is deemed to be operating normally, and its metering performance and output quality meet the requirements; if any indicator exceeds the qualified threshold range, the charging pile operation management platform will generate an alarm message indicating the relevant performance abnormality. For example, when a metering error exceeds the standard or voltage harmonic distortion is too high, the platform can mark the charging pile as needing maintenance and calibration, and notify maintenance personnel to handle it. The platform can also store all uploaded data in a database for long-term trend analysis and equipment health status assessment. Through big data analysis of historical data, the platform can statistically analyze charging pile failure rates, output efficiency trends, etc., assisting professionals in remotely diagnosing and locating problems and optimizing operation and maintenance strategies.

[0044] The beneficial effects of this invention are as follows: This invention realizes multi-dimensional real-time evaluation and early warning of the metering performance, power quality and safety status of charging piles, without the need for shutdown or manual on-site verification, which greatly improves verification efficiency, reduces operation and maintenance costs, and ensures metering accuracy and charging safety. Attached Figure Description

[0045] The present invention will now be further described with reference to the accompanying drawings.

[0046] Figure 1 This is a schematic diagram of the principle topology of the AC / DC charging pile metering performance and power quality tester of the present invention;

[0047] Figure 2 This is a diagram of the internal structure of the DC calibration and testing instrument of the present invention;

[0048] Figure 3 This is a diagram of the internal structure of the AC calibration tester of the present invention;

[0049] Figure 4 This is a schematic diagram of the DC calibration tester of the present invention;

[0050] Figure 5 This is a schematic diagram of the AC calibration tester of the present invention;

[0051] Figure 6 This is a flowchart of the testing process for this invention;

[0052] Figure 7 This is a voltage sampling diagram of the present invention;

[0053] Figure 8 This is a current sampling diagram of the present invention. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] like Figure 1 As shown in the figure, this embodiment is a remote detection method for the metering performance and output quality of electric vehicle charging piles, and its steps are as follows:

[0056] Step one: Connect the 0.1-level precision adapter-type metrological verification tester in series to the output circuit of the electric vehicle charging pile to be tested, positioning it between the charging pile and the electric vehicle. This allows for online monitoring of the charging process without affecting normal charging. After connection, perform range selection and status checks on each voltage and current measurement channel to confirm that the initial voltage and current readings are zero and the connections are reliable, with no looseness or poor contact. The internal structure of the DC verification tester is as follows: Figure 2 As shown, the internal structure of the AC calibration tester is as follows: Figure 3 As shown, both integrate metering, sampling, communication and timing modules to adapt to the output circuit detection requirements of different types of charging piles.

[0057] The testing instrument activates its built-in wireless communication module to establish a data communication link with the charging pile operation and management platform via a 4G or 5G wireless network. Simultaneously, the instrument's built-in GPS / BeiDou time synchronization module activates, acquiring a standard time signal and synchronizing with the instrument's internal clock. This ensures that the time base of the testing instrument, the charging pile control system, and the charging pile operation and management platform are consistent, with the time synchronization error preferably controlled within 1ms. The testing instrument then sends its own equipment identification information and the corresponding charging pile number to the charging pile operation and management platform to complete identity registration and access confirmation. This ensures that subsequent test data can be uploaded to the charging pile operation and management platform in real time and accurately for monitoring and analysis.

[0058] The above steps complete the physical access, communication link establishment, and clock synchronization of the calibration tester, laying the foundation for online testing of the subsequent charging process.

[0059] Step two: After completing the connection and communication configuration of the calibration tester as described in step one, an actual charging process is triggered, allowing the electric vehicle to charge under normal operating conditions. The calibration tester identifies the start and end of the charging process by monitoring the charging interface status signal or communication messages, thereby determining the energy measurement cycle.

[0060] For DC charging piles, such as Figure 4As shown, the testing instrument monitors the communication messages between the charging station and the vehicle's battery management system (BMS). When it receives the first frame message indicating that charging has begun, it determines that the charging process has started. For AC charging stations, such as... Figure 5 As shown, the calibration tester identifies the charging handshake completion status and determines the charging start time by detecting the voltage level and PWM duty cycle changes of the control pilot (CP) signal. After detecting the charging start signal, the calibration tester clears the internal energy accumulation counter and records the charging start time t0.

[0061] like Figure 6 As shown, throughout the charging process, the calibration and testing instrument acquires the voltage and current signals output by the charging pile in real time using a high-frequency sampling method. For AC charging piles, the AC voltage U of each phase is acquired separately. A U B U C and the corresponding phase current I A I B I C The instantaneous value is obtained, and the instantaneous power of each phase is calculated and then summed to obtain the total instantaneous power; for DC charging piles, the DC output voltage U is collected. DC and current I DC The instrument collects instantaneous data and calculates the corresponding instantaneous output power. Simultaneously, it periodically calculates and records the average voltage, current, and power values ​​to reflect the stability of the charging process.

[0062] The calibration and testing instrument performs numerical integration on the real-time power value, accumulating the electrical energy value throughout the entire charging process from the start time t0 to the end time t1. The integration process can be implemented using a high-frequency discrete accumulation method to improve the accuracy of the electrical energy calculation. When a charging termination condition is detected (such as the AC charging CP signal being disconnected, or the DC charging termination message arriving), the calibration and testing instrument stops sampling and integration, recording the charging termination time t1 and the final accumulated electrical energy value.

[0063] In this embodiment, the accumulated charging capacity obtained by the calibration tester under actual charging conditions is used as the standard charging capacity, denoted as Q. s This is used for subsequent comparison and analysis with the metering results of charging piles.

[0064] Step 3: After the charging process is complete, the calibration tester will measure the standard charging capacity Q obtained in Step 2. s The corresponding charging start and end time information is uploaded to the charging pile operation and management platform. Based on the charging start and end times, the platform retrieves the charging volume Q recorded for that charging order from the charging pile billing system. m It is the value of electricity measured by the built-in metering device of the charging pile and used for settlement.

[0065] The charging pile operation and management platform sets the standard charging capacity Q. s Charging capacity Q of charging station m Compare and calculate the metering error δ of the built-in metering device in the charging pile. Q The calculation formula is as follows:

[0066]

[0067] The charging pile operation and management platform will calculate δ Q Compare with the permissible error limits specified in the metrological verification procedures or relevant technical specifications. When δ Q When the value is within the allowable deviation range, the metering performance of the charging pile is deemed to meet the requirements; when δ Q If the readings exceed the permissible range, the charging station is deemed to have inaccurate metering, and a corresponding metering anomaly record is generated.

[0068] The measurement error results obtained in step three serve as an important basis for the remote verification of the metering performance of charging piles and will also be used as one of the input data for subsequent comprehensive performance evaluation and alarm determination.

[0069] Step four: During the charging process and under steady-state operating conditions, the calibration and testing instrument continuously monitors and analyzes the output voltage of the charging pile to obtain the accuracy and stability indicators of the charging pile's output voltage, thereby evaluating the accuracy and stability of the charging pile's output voltage. The sampling method for the output voltage can be found in [reference needed]. Figure 7 .

[0070] For AC charging piles, the calibration tester measures the effective value and frequency parameters of the output voltage to evaluate voltage amplitude and frequency deviations. For DC charging piles, the calibration tester measures the average value of the output voltage and compares it with the charging pile's rated output voltage or current setting to evaluate voltage regulation accuracy. Output voltage deviation can be expressed as a relative error, calculated using the following formula:

[0071]

[0072] Among them, V out The measured output voltage value of the calibration tester is shown in V. Under AC conditions, it is the effective voltage value; under DC conditions, it is the steady-state average voltage. nom The rated output voltage or set output voltage of the charging station.

[0073] Based on voltage deviation calculations, the calibration tester analyzes voltage fluctuations during charging by combining real-time sampling data. For example, when the charging current changes, it monitors whether there is a significant voltage drop, overshoot, or recovery delay, and records the transient voltage fluctuation amplitude and recovery time. When the voltage deviation exceeds a preset threshold, or the voltage fluctuation characteristics do not meet the relevant technical standards, it is determined that the output voltage quality of the charging pile is abnormal.

[0074] This step of the test obtains the accuracy and stability indicators of the charging pile's output voltage under actual operating conditions, providing basic data support for subsequent power quality analysis and comprehensive performance evaluation.

[0075] Step five: During the charging process, the calibration and testing instrument monitors and analyzes the dynamic response characteristics of the charging pile's output current to obtain the dynamic response index of the charging pile's output current control, thereby evaluating the charging pile's current control performance under load variation conditions. The sampling method for the output current can be found in [reference needed]. Figure 8 .

[0076] For DC electric vehicle charging stations, the calibration tester monitors the communication messages between the charging station and the vehicle's battery management system (BMS) to obtain the target charging current demand value I of the vehicle during the charging process in real time. req When the vehicle's BMS requests a sudden change in charging current (e.g., a switch from constant current to constant voltage during charging, or the vehicle adjusting its charging strategy based on battery status), the calibration tester simultaneously records the actual output current I of the charging pile. out The response process that changes over time.

[0077] The calibration tester identifies the peak current I that occurs during the current response process based on the acquired current waveform. max And the final stable steady-state current value I steady And based on this, the current overshoot percentage σ is calculated. I It is used to quantify the degree of current overshoot, and its calculation formula is:

[0078]

[0079] Among them, I max I represents the peak current that occurs during the current response process. steady The steady-state target current value; calculated by σ I The overshoot percentage of the current relative to the steady-state target current value is obtained; at the same time, the calibration instrument measures the time required for the current to reach a certain proportion (e.g., 95%) of the steady-state target value from the start of the change, in order to reflect the current response speed.

[0080] If a large current overshoot or excessively long response time is detected, it indicates poor current control performance of the charging pile under varying load conditions, which may adversely affect battery charging safety or charging efficiency. The tester will mark the corresponding current waveform and the time point of the anomaly, and upload it to the platform as a dynamic performance anomaly record.

[0081] In addition, the calibration tester can also analyze the changes in current dynamic response performance at different charging stages by combining the vehicle battery status information (such as SOC range) during the charging process, providing a basis for subsequent performance degradation analysis.

[0082] For AC electric vehicle charging stations, since the charging current is mainly determined by the vehicle's on-board charger, the tester focuses on monitoring the relationship between current changes and grid voltage under varying charging load conditions. The tester records the changes in AC output current and, combined with the voltage fluctuation data obtained in step four, comprehensively assesses the dynamic stability of the AC power supply system under varying load conditions.

[0083] When an abnormal phenomenon such as a significant voltage drop or slow recovery is detected during a current change, the tester records the event as an abnormality in the dynamic performance of the AC output.

[0084] Step six: For AC electric vehicle charging piles, the calibration tester performs harmonic analysis on the output voltage and current waveforms of the charging pile, calculates the harmonic distortion, and obtains the AC harmonic index of the AC output of the charging pile to evaluate the AC output power quality.

[0085] During charging, the calibration instrument uses high-frequency sampling data to perform Discrete Fourier Transform (DFT or FFT) on the output voltage and current waveforms to extract the effective values ​​and phase information of the fundamental component and each harmonic component. The instrument calculates the harmonic distortion (THD) of the output voltage and output current, and can further analyze the proportion of each harmonic (such as the 3rd, 5th, and 7th harmonics).

[0086] Harmonic distortion quantitatively reflects the degree of waveform distortion. The formula for calculating the harmonic distortion of the output voltage is as follows:

[0087]

[0088] Where U1 is the effective value of the fundamental component, U n Let N be the effective value of the nth harmonic component, where n ≥ 2, and N is the highest harmonic order.

[0089] The calibration tester compares the calculated THD value with the limits specified in power quality standards or relevant technical specifications. For example, if the THD of the output voltage exceeds 5%, the harmonic content of the AC output voltage is determined to be too high. For cases exceeding the limit, the tester further analyzes whether there are specific harmonic anomalies to help determine possible rectification, inversion, or control abnormalities.

[0090] During harmonic analysis, the calibration tester can also simultaneously record power quality-related parameters such as power factor and three-phase voltage imbalance, which are used to comprehensively evaluate the power supply quality of AC charging piles. If any power quality indicator fails to meet the requirements, the calibration tester will mark the test result as unqualified and record the corresponding abnormal parameters and time information.

[0091] Step 7: For DC electric vehicle charging piles, the calibration tester detects and analyzes the ripple component in the DC output voltage to obtain the DC ripple index of the charging pile's DC output voltage, in order to evaluate the purity and stability of the DC output voltage.

[0092] The calibration tester performs high-frequency sampling of the DC output voltage during charging and extracts the maximum, minimum, and average instantaneous values ​​of the voltage waveform over one or more switching cycles through time-domain analysis. Based on this, the tester calculates the ripple coefficient of the DC output voltage to quantify the magnitude of the AC interference component in the DC output.

[0093] Ripple is characterized by the ripple coefficient, which is defined as the percentage of the peak-to-peak output voltage relative to the average DC value. The calculation formula is as follows:

[0094]

[0095] Among them, V max V represents the maximum instantaneous value of the DC output voltage during the switching cycle. min V is the minimum instantaneous value within the switching cycle. dc This represents the average value of the DC output voltage.

[0096] Meanwhile, the calibration and testing instrument can combine frequency domain analysis methods to perform Fourier transform on the acquired voltage waveform, identify the power frequency component or switching frequency component superimposed in the DC output, and thus distinguish ripple interference from different sources.

[0097] The calibration tester compares the calculated ripple coefficient with relevant technical standards or preset thresholds. When the ripple coefficient exceeds the allowable range, the DC output power quality is deemed unqualified. The calibration tester records the abnormal ripple data, corresponding time points, and relevant spectral characteristics for subsequent analysis and fault location.

[0098] Step 8: After completing the above tests, the calibration instrument summarizes and organizes the data on metering performance, voltage quality, current dynamic response, power quality, and safety-related data during the charging process, and generates the complete test results for this remote online test.

[0099] The testing instrument uploads the test results to the charging pile operation management platform via the wireless communication link established in step one. The uploaded data includes, but is not limited to: charging pile identification information, test start and end times, and standard charging capacity Q. s Measurement error δ Q Voltage deviation index, current dynamic response index, AC harmonic index, DC ripple index, and abnormal event records, etc.

[0100] The platform parses and stores the received data, and compares each detection indicator with the preset pass threshold. When all detection indicators are within the pass range, the platform determines that the charging pile is operating normally; when any indicator exceeds the allowable range, the platform generates corresponding alarm information and adds the charging pile to the key monitoring or maintenance list.

[0101] In a preferred embodiment, the platform can also combine historical test data uploaded by the testing instrument to conduct long-term trend analysis of the charging pile's operating status, such as statistical metering error trends, power quality degradation trends, and the frequency of anomalies, thereby assisting maintenance personnel in remote diagnosis and predictive maintenance decisions. Through the above comprehensive judgment and data analysis, unattended remote monitoring of the charging pile's metering performance, power quality, and operational safety status can be achieved.

[0102] Furthermore, the testing instrument simultaneously monitors the safety status of the charging interface online during the charging process to further ensure the safety of the charging process.

[0103] Specifically, temperature sensors are arranged at the metal contact points on both the charging gun head and the charging pile base. These sensors are installed close to key locations prone to increased contact resistance and are used to collect real-time temperature data at the charging interface. The optimal sampling frequency for the temperature data is 1Hz to balance real-time performance and data stability.

[0104] The tester is pre-set with safety threshold parameters for interface temperature, including a warning temperature threshold T1 (e.g., 70℃) and an alarm shutdown temperature threshold T2 (e.g., 80℃), and sets duration criteria, such as determining a valid temperature abnormality event when the monitored temperature continuously exceeds the threshold for no less than 5 seconds.

[0105] When the temperature at any monitoring point exceeds the warning temperature threshold T1 and the duration meets the criteria, the tester sends an over-temperature warning to the charging pile operation management platform via the wireless communication module to indicate that there is an abnormal temperature rise trend in the charging interface. When the monitored temperature rises further and reaches the alarm shutdown temperature threshold T2, the tester triggers the safety protection mechanism and sends an emergency shutdown command to the charging pile control system to terminate the charging process, thereby preventing safety accidents caused by overheating.

[0106] During temperature monitoring, the testing instrument also associates and annotates the time points of temperature anomalies with corresponding voltage, current, and energy measurement data to analyze the potential impact of temperature rise on metering accuracy and power quality measurement results. After receiving temperature-related detection data, the platform incorporates it into a comprehensive evaluation along with metering performance and power quality test results. Multiple test results can be stored in a historical database for subsequent safety status trend analysis and predictive maintenance decisions.

[0107] It should be understood that any parts not described in detail in this specification belong to the prior art. Those skilled in the art should understand that the above embodiments are merely to help readers understand the principles and implementation methods of the present invention, and the scope of protection of the present invention is not limited to such embodiments. All equivalent substitutions made based on the present invention are within the scope of protection of the present invention.

Claims

1. A remote detection method for the metering performance and output quality of electric vehicle charging piles, characterized in that, include: Step 1: Connect the calibration tester used for remote measurement to the output circuit of the electric vehicle charging pile to be calibrated, and complete the connection between the charging pile and the electric vehicle; start the calibration tester and establish a data communication link with the charging pile operation management platform through its built-in communication module; Step 2: Trigger an actual charging process and use a calibration tester to monitor the output of the charging pile throughout the process. Obtain the metering information of the charging pile under actual working conditions. The charging power accumulated by the calibration tester is used as the standard charging power. Step 3: After charging is completed, the calibration and testing instrument uploads the standard charging amount obtained in Step 2 to the charging pile operation and management platform; the charging pile operation and management platform obtains the charging amount recorded by the corresponding charging pile billing system according to the charging start and end time, and calculates the measurement error of the charging pile's built-in metering device based on the charging amount and the standard charging amount. Step 4: During the charging process and under steady-state conditions, monitor and analyze the output voltage of the charging pile to obtain the deviation index of the output voltage and evaluate the fluctuation / stability of the output voltage. Step 5: Use a calibration tester to monitor the dynamic response characteristics of the charging pile's output current and obtain the dynamic response index of the charging pile's output current control. Step 6: For AC charging piles, the calibration tester performs harmonic analysis on the output voltage and current waveforms, calculates the harmonic distortion, and obtains the AC harmonic index of the charging pile's AC output. Step 7: For DC charging piles, the calibration tester detects and analyzes the ripple component in the output voltage to obtain the DC ripple index of the DC output voltage of the charging pile. Step 8: After completing the above tests, the calibration instrument summarizes and organizes the data on metering performance, voltage quality, current dynamic response, and power quality during the charging process, and generates a complete test result for remote online testing.

2. The remote detection method for metering performance and output quality of electric vehicle charging piles according to claim 1, characterized in that, In step two, the charging communication messages between the electric vehicle and the charging pile are analyzed to identify the start and end times of charging, thereby determining the energy measurement cycle. During the charging process, the calibration tester collects the voltage and current signals output by the charging pile in real time, and accumulates and integrates the instantaneous power to obtain the total charging capacity of the entire charging process, while recording key parameters during the charging process.

3. The remote detection method for metering performance and output quality of electric vehicle charging piles according to claim 1, characterized in that, In step three, the measurement error δ Q Calculate using the following formula: Among them, Q m The charging capacity of the charging station, Q s Standard charging capacity; The measurement error δ Q Compared with the specified error limit, if δ Q If the deviation is within the allowable range, it indicates that the metering performance of the charging pile is qualified; if it exceeds the allowable range, it is determined that the metering of the charging pile is inaccurate.

4. The remote detection method for metering performance and output quality of electric vehicle charging piles according to claim 1, characterized in that, In step four, if it is an AC charging pile, the calibration tester measures the effective value and frequency of the output voltage and evaluates the voltage amplitude deviation and frequency deviation; if it is a DC charging pile, the average value of the output voltage is measured and compared with its set value or rated value to evaluate the voltage regulation accuracy.

5. The remote detection method for metering performance and output quality of electric vehicle charging piles according to claim 4, characterized in that, In step four, the output voltage deviation is expressed as the relative error δ. V The calculation formula is as follows: Among them, V out This is the average value of the output voltage measured by the calibration tester; the effective value is given under AC conditions, and the steady-state voltage is given under DC conditions; V nom The rated output voltage or current setting value of the charging pile is determined by δ. V The output voltage deviation is obtained; if the output voltage deviation exceeds the preset threshold, it is considered that there is a problem with the quality of the charging pile's output voltage.

6. The remote detection method for metering performance and output quality of electric vehicle charging piles according to claim 1, characterized in that, In step four, the calibration instrument evaluates voltage stability based on the collected data; If abnormal voltage fluctuations are detected, it is considered that there is a problem with the quality of the charging pile's output voltage.

7. The remote detection method for metering performance and output quality of electric vehicle charging piles according to claim 1, characterized in that, In step five, when the charging current changes abruptly, record the current change curve over time, analyze the response speed of current rise or fall, and whether overshoot occurs; define the current overshoot percentage σ. I The formula used to quantify the degree of current overshoot is as follows: Among them, I max I represents the peak current that occurs during the current response process. steady The steady-state target current value; calculated by σ I The percentage overshoot of the current relative to the steady-state target current value is obtained, and the current response time t is measured simultaneously. r The current response is measured by the current control system. The calibration instrument obtains the waveform characteristics of the current response based on the collected data to determine the quality of the charging pile's current control.

8. The remote detection method for metering performance and output quality of electric vehicle charging piles according to claim 1, characterized in that, In step six, harmonic distortion quantitatively reflects the degree of waveform distortion. The formula for calculating the harmonic distortion of the output voltage is as follows: Where U1 is the effective value of the fundamental component, U n Let N be the effective value of the nth harmonic component, where n ≥ 2, and N is the highest harmonic order.

9. The remote detection method for metering performance and output quality of electric vehicle charging piles according to claim 1, characterized in that, In step seven, the ripple index is characterized by the ripple coefficient, which is defined as the percentage of the peak-to-peak output voltage relative to the average DC value. The calculation formula is as follows: Among them, V max V represents the maximum instantaneous value of the DC output voltage during the switching cycle. min V is the minimum instantaneous value within the switching cycle. dc This represents the average value of the DC output voltage.

10. The remote detection method for metering performance and output quality of electric vehicle charging piles according to claim 1, characterized in that, In step eight, the charging pile operation management platform compares each measured indicator with the pre-set qualified threshold one by one: if all measured indicators are within the qualified threshold range, the charging pile is determined to be in normal operation and the metering performance and output quality meet the requirements; if any indicator exceeds the qualified threshold range, the charging pile operation management platform will generate an alarm message to indicate the relevant performance abnormality.

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