Method for analyzing influence of multi-access electric vehicle charging pile on power grid harmonic waves

Abstract

The invention relates to the technical field of power grid influence analysis, and relates to a method for analyzing the influence of multi-access electric vehicle charging piles on power grid harmonic waves, which comprises the following steps: setting a monitoring time period, and simulating that the multi-access electric vehicle charging piles are accessed to a power grid under the set number; collecting power grid load data under each set number of electric vehicle charging piles in the current monitoring time period, and performing prediction analysis on the power grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period according to the power grid load data, the maximum number of the electric vehicle charging piles which can be accessed to the power grid in each future monitoring time period is determined according to the maximum number and the set power grid harmonic tolerance threshold value and is output to an external device, the number and distribution of the charging piles are reasonably controlled by scientifically analyzing the influence of the access of the charging piles on the harmonic pollution of the power grid, the load of the power grid can be effectively reduced, and the reliability of the power grid is improved. The stability and the power supply quality of the power grid are improved, and the configuration and the utilization of power resources are optimized.

Description

Technical Field

[0001] The invention belongs to the technical field of power grid influence analysis and relates to a method for analyzing the influence of multiple access electric vehicle charging piles on power grid harmonics. Background Art

[0002] With the proposal of the "dual carbon" goal, energy transformation and upgrading are accelerating, and the construction of a new power system is imminent. On the supply side, new energy represented by wind power and photovoltaics has developed rapidly, and the trend of clean and low-carbon energy production has become irreversible: on the demand side, electric energy substitution represented by electric vehicles has penetrated widely, and electrification and diversification of energy consumption have become popular. In recent years, as an important part of electric vehicles, the number of private passenger electric vehicles has grown rapidly, and the harmonic content of charging loads has increased sharply. Electric vehicle chargers are nonlinear electrical equipment and will generate large harmonic components when working.

[0003] The harmonic hazards of charging piles are mainly reflected in the damage to electronic equipment. This harmonic enters the electric vehicle charging facilities through the power lines of the charging station. Harmonics will increase the consumption of metal in the transformer, causing the transformer temperature to rise, thereby reducing the service life of the transformer. In addition, due to the influence of the harmonic magnetic field itself, the machine will vibrate inside, and even resonance will occur in severe cases, causing damage to the machine. When this harmonic component is finally injected into the public power grid, it will cause problems such as power grid loss and excessive equipment temperature, reduce the service life of communication equipment, and cause distortion. Not only that, harmonic pollution will also affect the accuracy of detection equipment and have a serious adverse impact on subsequent management. Most of the load power supply must be supplied to users after equipment conversion. With the continuous increase in users, the influx of such loads will greatly increase the probability of power accidents. The harmonics generated during the operation of power electronic devices will have a great impact on the safety of the power grid and the production level of users. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention provides a method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics, which is used to solve the above technical problems.

[0005] In order to achieve the above purpose and other purposes, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides a method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics, the method comprising the following steps: Step S1, setting a monitoring time period, simulating multiple electric vehicle charging piles to be connected to the power grid at a set number, and collecting power grid load data at each set number of electric vehicle charging piles in the current monitoring time period; Step S2: Based on the grid load data, predict and analyze the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period; Step S3: setting a grid harmonic tolerance threshold, and determining the maximum number of electric vehicle charging piles that can be connected to the grid in each future monitoring time period based on the grid harmonic tolerance threshold and the prediction analysis results of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period; Step S4: output the maximum number of electric vehicle charging piles that can be connected to the power grid in each future monitoring time period to an external device for further operation processing.

[0006] Exemplarily, in step S1, multiple electric vehicle charging piles are simulated to be connected to the power grid at a set number, and the specific simulation process is: The maximum carrying capacity of the power grid, the maximum charging power value of electric vehicles, and the total number of target electric vehicle charging piles in the current monitoring time period are obtained from the reference information library, and they are respectively imported into the simulation model of the power system analysis software. At the beginning of the simulation, the status of the charging piles is initialized to all idle, and the current load of the power grid is set to zero. The simulation is performed according to time steps: at each time point, the newly arrived electric vehicles are checked and the charging piles are assigned, the status of the charging electric vehicles is updated, the charging piles of the electric vehicles that have completed charging are released, and the status of the charging piles and the power grid load data are updated.

[0007] Exemplarily, the grid load data for each set number of electric vehicle charging piles in the current monitoring time period in step S1 includes harmonic distortion rate, K factor and harmonic power factor.

[0008] Exemplarily, the grid load data under each set number of electric vehicle charging piles in the current monitoring time period is collected, and the specific collection process is as follows: According to the simulation model of the power system analysis software, the current value corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period is obtained, and the collected time series data is converted using the FFT algorithm, thereby converting it from the time domain to the frequency domain, thereby converting each monitoring time point in the current monitoring time period into each frequency point in the current monitoring time period, and further calculating the current peak amplitude of each harmonic component corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period , j represents the number of each monitoring time point, j=1,2,...i, c represents the number of each set number of electric vehicle charging piles, c=1,2,...f, v represents the number of each harmonic component, v=1,2,...d, thus obtaining the current effective value of each harmonic component under each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period ; The current peak amplitude of each harmonic component at each monitoring time point corresponding to each set number of electric vehicle charging piles in the current monitoring time period , They respectively represent the real part and imaginary part of the complex number corresponding to the jth monitoring time point in the current monitoring time period corresponding to the vth harmonic component under the cth set number of electric vehicle charging piles in the FFT result; Finally, the harmonic distortion rate under each set number of electric vehicle charging piles in the current monitoring time period is calculated through the THD harmonic distortion rate calculation formula; It needs to be explained that the harmonic distortion rate under each set number of electric vehicle charging piles during the current monitoring period is , i is the total number of monitoring time points in the current monitoring time period; Comprehensive analysis obtains the K coefficient for each set number of electric vehicle charging piles during the current monitoring period , v represents the order of each harmonic component, The effective value of the fundamental current under the c-th set number of electric vehicle charging piles at the j-th monitoring time point in the current monitoring time period. The specific acquisition process is as follows: The first harmonic component corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period is designated as the fundamental current corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period.

[0009] Exemplarily, the grid load data under each set number of electric vehicle charging piles in the current monitoring time period is collected, and the specific collection process also includes the following steps: According to the simulation model of the power system analysis software, the current value corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring period is obtained and voltage value ; Calculate the active power corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring period ; Calculate the harmonic reactive power at each monitoring time point corresponding to each set number of electric vehicle charging piles during the current monitoring period ,in It represents the voltage effective value of the vth harmonic component at the jth monitoring time point corresponding to the cth set number of electric vehicle charging piles in the current monitoring period, Represents the phase difference between the voltage and current of the vth harmonic component; Calculate the distortion power at each monitoring time point corresponding to each set number of electric vehicle charging piles during the current monitoring period ,in They represent the apparent power and reactive power at the cth set number of electric vehicle charging piles corresponding to the jth monitoring time point in the current monitoring period respectively; Said The specific calculation process is as follows: ,in, is the power factor at each monitoring time point in the current monitoring time period, representing the cosine value of the phase difference between the voltage and current waveforms at each monitoring time point in the current monitoring time period; , It is the sine value of the power factor, representing the sine value of the phase difference between the voltage and current waveforms at each monitoring time point in the current monitoring time period.

[0010] Comprehensively calculate the harmonic power factor under each set number of electric vehicle charging piles in the current monitoring time period .

[0011] Exemplarily, in step S2, a prediction analysis is performed on the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period, and the specific analysis process is as follows: Extracting grid load data for each set number of electric vehicle charging piles in each historical monitoring period from a reference information database; According to the harmonic distortion rate of each set number of electric vehicle charging piles in the current monitoring time period And the harmonic distortion rate under each set number of electric vehicle charging piles in each historical monitoring period , m represents the number of each historical monitoring time period, m=1,2,...q; The harmonic distortion rates under each set number of electric vehicle charging piles in each historical monitoring period and the harmonic distortion rates under each set number of electric vehicle charging piles in the current monitoring period are arranged in sequence according to the time series, thereby obtaining the set of harmonic distortion rates under each set number of electric vehicle charging piles in the monitoring period. ; The harmonic distortion rate of each set number of electric vehicle charging piles in the first future monitoring period is calculated based on the ARIMA model. , where c represents the set constant term, is the coefficient of the autoregressive term, The harmonic distortion rate under the set number of electric vehicle charging piles in the qth historical monitoring period and the cth historical monitoring period, respectively, calculating a correction factor for a predetermined error; According to the calculation method of the harmonic distortion rate under each set number of electric vehicle charging piles in the first future monitoring time period, the harmonic distortion rate under each set number of electric vehicle charging piles in the second future monitoring time period, the third future monitoring time period to the nth future monitoring time period is calculated in the same way, and the harmonic distortion rate under each set number of electric vehicle charging piles in each future monitoring time period is obtained by integrating them. , n represents the number of each future monitoring time period, n=1,2,...p; Based on the harmonic distortion rate under the set number of electric vehicle charging piles in each future monitoring period, the K coefficient under the set number of electric vehicle charging piles in each future monitoring period is calculated in the same way. Harmonic Power Factor ; The harmonic distortion rate, K factor and harmonic power factor under each set number of electric vehicle charging piles in each future monitoring period are normalized, and a comprehensive analysis is performed to obtain a comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring period. , b1, b2 and b3 represent the weight factors of the harmonic level corresponding to the set harmonic distortion rate, K factor and harmonic power factor, respectively, and b1+b2+b3=1, They are respectively expressed as the harmonic distortion rate, K factor and harmonic power factor under the cth set number of electric vehicle charging piles in the nth future monitoring period after the standard.

[0012] Exemplarily, the power grid harmonic tolerance threshold is set, and the specific process is as follows: Filter out the power grid harmonic level values ​​in each historical monitoring period from the reference information database, arrange them in descending order, and obtain the maximum value of the power grid harmonic level; The power grid harmonic level value in each historical monitoring period is calculated to obtain the power grid harmonic standard deviation value in the historical monitoring period; Grid harmonic tolerance threshold = maximum grid harmonic level + a*grid harmonic standard deviation value in the historical monitoring period; Where a represents a predefined safety factor.

[0013] Exemplarily, before determining the maximum number of electric vehicle charging piles that can be connected to the power grid in each future monitoring time period, the following steps are also included: The grid harmonic tolerance threshold is compared with the comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring period. If the comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in a future monitoring period is greater than the grid harmonic tolerance threshold, it indicates that the current state of the grid is not suitable for connecting more electric vehicle charging piles; If the comprehensive evaluation values ​​of the grid harmonic levels under the set number of electric vehicle charging piles in a future monitoring period are all less than or equal to the grid harmonic tolerance threshold, the next step is executed; If in a future monitoring time period, there is both a comprehensive evaluation value of the grid harmonic level under a certain set number of electric vehicle charging piles that is greater than or equal to the grid harmonic tolerance threshold and a comprehensive evaluation value of the grid harmonic level under a certain set number of electric vehicle charging piles that is less than the grid harmonic tolerance threshold, then the maximum set number of electric vehicle charging piles with a comprehensive evaluation value of the grid harmonic level less than the grid harmonic tolerance threshold is selected as the maximum number of electric vehicle charging piles that can be connected to the grid in each future monitoring time period.

[0014] Exemplarily, the maximum number of electric vehicle charging piles that can be connected to the power grid in each future monitoring time period is determined by: The possible harmonic generation value of a single charging pile is extracted from the reference information database, and the comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period is subtracted from the set grid harmonic tolerance threshold. The subtraction result is then divided by the possible harmonic generation value of a single charging pile, and the maximum number of electric vehicle charging piles that can be connected to the grid in each future monitoring time period is obtained.

[0015] Another aspect of the present invention provides a device for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics, including an electronic device and a computer-readable storage medium; The electronic device comprises a processor, a memory and a communication bus, wherein the memory stores a computer-readable program executable by the processor; The communication bus realizes the connection and communication between the processor and the memory; When the processor executes the computer-readable program, the steps in the above-mentioned method for analyzing the impact of multiple electric vehicle charging piles on power grid harmonics are implemented; The computer-readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in the above-mentioned method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics.

[0016] As described above, the method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics provided by the present invention has at least the following beneficial effects: (1) The present invention provides a method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics. By setting a monitoring time period, simulating multiple access electric vehicle charging piles to access the power grid at a set number, collecting power grid load data at each set number of electric vehicle charging piles in the current monitoring time period, and predicting and analyzing the power grid harmonic level at each set number of electric vehicle charging piles in each future monitoring time period based on the power grid load data, and determining the maximum number of electric vehicle charging piles that can be accessed to the power grid in each future monitoring time period by comparing the data with the set power grid harmonic tolerance threshold, and outputting the data to an external device for operation and processing. By scientifically analyzing the impact of charging pile access on power grid harmonic pollution and reasonably controlling the number and distribution of charging piles, the power grid burden can be effectively reduced and the stability and power supply quality of the power grid can be improved. Secondly, reasonably controlling the number of access charging piles can also help optimize the configuration and utilization of power resources. With the popularization of electric vehicles, the charging demand has increased dramatically. If it is not controlled, it may cause excessive load on the power grid and affect the normal operation of the power grid. By scientifically managing the access of charging piles, the power grid load can be better balanced and power grid overload can be avoided, thereby improving the utilization efficiency of electric energy and reducing energy waste.

[0017] (2) The embodiments of the present invention analyze the harmonic pollution caused by charging piles to the power grid and control the number of charging piles connected to the power grid accordingly, which not only helps to ensure the stable operation of the power grid and optimize energy utilization, but also provides a more stable and efficient charging environment for electric vehicles, promotes the healthy development of the electric vehicle industry, and can effectively improve the stability and power supply quality of the power grid, optimize energy utilization, and provide good infrastructure support for the healthy development of electric vehicles, which has far-reaching significance for promoting the sustainable development of society. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of the connection of each step of the method of the present invention.

[0020] Figure 2 It is a schematic diagram of the structure of the device shown in the present invention. DETAILED DESCRIPTION

[0021] The above contents in combination with the implementation of the present invention are merely examples and explanations of the concept of the present invention. The technical personnel in the relevant technical field may make various modifications or supplements to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

[0022] Example 1 See also Figure 1 As shown, a method for analyzing the impact of multiple electric vehicle charging piles on power grid harmonics includes the following steps: Step S1, setting a monitoring time period, simulating multiple electric vehicle charging piles to be connected to the power grid at a set number, and collecting power grid load data at each set number of electric vehicle charging piles in the current monitoring time period; It should be added that in step S1, multiple electric vehicle charging piles are simulated to be connected to the power grid at a set number, and the specific simulation process is as follows: The maximum carrying capacity of the power grid, the maximum charging power value of electric vehicles, and the total number of target electric vehicle charging piles in the current monitoring time period are obtained from the reference information library, and they are respectively imported into the simulation model of the power system analysis software. At the beginning of the simulation, the status of the charging piles is initialized to all idle, and the current load of the power grid is set to zero. The simulation is performed according to time steps: at each time point, the newly arrived electric vehicles are checked and the charging piles are assigned, the status of the charging electric vehicles is updated, the charging piles of the electric vehicles that have completed charging are released, and the status of the charging piles and the power grid load data are updated.

[0023] It should be added that the grid load data for each set number of electric vehicle charging piles in the current monitoring time period in step S1 includes harmonic distortion rate, K factor and harmonic power factor.

[0024] It should be added that the grid load data under each set number of electric vehicle charging piles in the current monitoring period is collected. The specific collection process is as follows: According to the simulation model of the power system analysis software, the current value corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period is obtained, and the collected time series data is converted using the FFT algorithm, thereby converting it from the time domain to the frequency domain, thereby converting each monitoring time point in the current monitoring time period into each frequency point in the current monitoring time period, and further calculating the current peak amplitude of each harmonic component corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period , j represents the number of each monitoring time point, j=1,2,...i, c represents the number of each set number of electric vehicle charging piles, c=1,2,...f, v represents the number of each harmonic component, v=1,2,...d, thus obtaining the current effective value of each harmonic component under each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period ; It needs to be explained that .

[0025] The current peak amplitude of each harmonic component at each monitoring time point corresponding to each set number of electric vehicle charging piles in the current monitoring time period , They respectively represent the real part and imaginary part of the complex number corresponding to the jth monitoring time point in the current monitoring time period corresponding to the vth harmonic component under the cth set number of electric vehicle charging piles in the FFT result; It should be supplemented that the real part and imaginary part of the complex number corresponding to each harmonic component at each frequency point corresponding to each set number of electric vehicle charging piles in the current monitoring time period are obtained and recorded as the real part and imaginary part of the complex number corresponding to each harmonic component at each monitoring time point corresponding to each set number of electric vehicle charging piles in the current monitoring time period.

[0026] Finally, the harmonic distortion rate under each set number of electric vehicle charging piles in the current monitoring time period is calculated through the THD harmonic distortion rate calculation formula; It needs to be explained that the harmonic distortion rate under each set number of electric vehicle charging piles during the current monitoring period is , i is the total number of monitoring time points in the current monitoring time period; Comprehensive analysis obtains the K coefficient for each set number of electric vehicle charging piles during the current monitoring period , v represents the order of each harmonic component, The effective value of the fundamental current under the c-th set number of electric vehicle charging piles at the j-th monitoring time point in the current monitoring time period. The specific acquisition process is as follows: The first harmonic component corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period is designated as the fundamental current corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period.

[0027] It should be noted that the K factor is a parameter used to evaluate the impact of harmonic components on the distribution system, which takes into account the frequency and amplitude of the harmonic components.

[0028] It should be added that the grid load data under each set number of electric vehicle charging piles in the current monitoring period is collected, and the specific collection process also includes the following steps: According to the simulation model of the power system analysis software, the current value corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring period is obtained and voltage value ; Calculate the active power corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring period ; Calculate the harmonic reactive power at each monitoring time point corresponding to each set number of electric vehicle charging piles during the current monitoring period ,in It represents the voltage effective value of the vth harmonic component at the jth monitoring time point corresponding to the cth set number of electric vehicle charging piles in the current monitoring period, Represents the phase difference between the voltage and current of the vth harmonic component; Calculate the distortion power at each monitoring time point corresponding to each set number of electric vehicle charging piles during the current monitoring period ,in They represent the apparent power and reactive power at the cth set number of electric vehicle charging piles corresponding to the jth monitoring time point in the current monitoring period respectively; Said The specific calculation process is as follows: ,in, is the power factor at each monitoring time point in the current monitoring time period, representing the cosine value of the phase difference between the voltage and current waveforms at each monitoring time point in the current monitoring time period; , It is the sine value of the power factor, representing the sine value of the phase difference between the voltage and current waveforms at each monitoring time point in the current monitoring time period.

[0029] Comprehensively calculate the harmonic power factor under each set number of electric vehicle charging piles in the current monitoring time period .

[0030] Step S2: Based on the grid load data, predict and analyze the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period; It should be added that in step S2, the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period is predicted and analyzed, and the specific analysis process is as follows: Extracting grid load data for each set number of electric vehicle charging piles in each historical monitoring period from a reference information database; According to the harmonic distortion rate of each set number of electric vehicle charging piles in the current monitoring time period And the harmonic distortion rate under each set number of electric vehicle charging piles in each historical monitoring period , m represents the number of each historical monitoring time period, m=1,2,...q; The harmonic distortion rates under each set number of electric vehicle charging piles in each historical monitoring period and the harmonic distortion rates under each set number of electric vehicle charging piles in the current monitoring period are arranged in sequence according to the time series, thereby obtaining the set of harmonic distortion rates under each set number of electric vehicle charging piles in the monitoring period. ; The harmonic distortion rate of each set number of electric vehicle charging piles in the first future monitoring period is calculated based on the ARIMA model. , where c represents the set constant term, is the coefficient of the autoregressive term, The harmonic distortion rate under the set number of electric vehicle charging piles in the qth historical monitoring period and the cth historical monitoring period, respectively, calculating a correction factor for a predetermined error; According to the calculation method of the harmonic distortion rate under each set number of electric vehicle charging piles in the first future monitoring time period, the harmonic distortion rate under each set number of electric vehicle charging piles in the second future monitoring time period, the third future monitoring time period to the nth future monitoring time period is calculated in the same way, and the harmonic distortion rate under each set number of electric vehicle charging piles in each future monitoring time period is obtained by integrating them. , n represents the number of each future monitoring time period, n=1,2,...p; Based on the harmonic distortion rate under the set number of electric vehicle charging piles in each future monitoring period, the K coefficient under the set number of electric vehicle charging piles in each future monitoring period is calculated in the same way. Harmonic Power Factor ; The harmonic distortion rate, K factor and harmonic power factor under each set number of electric vehicle charging piles in each future monitoring period are normalized, and a comprehensive analysis is performed to obtain a comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring period. , b1, b2 and b3 represent the weight factors of the harmonic level corresponding to the set harmonic distortion rate, K factor and harmonic power factor, respectively, and b1+b2+b3=1, They are respectively expressed as the harmonic distortion rate, K factor and harmonic power factor under the cth set number of electric vehicle charging piles in the nth future monitoring period after the standard.

[0031] It should be added that the maximum and minimum values ​​are used to normalize the harmonic distortion rate, K factor and harmonic power factor at each set number of electric vehicle charging piles in each future monitoring time period.

[0032] Step S3: setting a grid harmonic tolerance threshold, and determining the maximum number of electric vehicle charging piles that can be connected to the grid in each future monitoring time period based on the grid harmonic tolerance threshold and the prediction analysis results of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period; It should be added that the specific process of setting the grid harmonic tolerance threshold is as follows: Filter out the power grid harmonic level values ​​in each historical monitoring period from the reference information database, arrange them in descending order, and obtain the maximum value of the power grid harmonic level; The power grid harmonic level value in each historical monitoring period is calculated to obtain the power grid harmonic standard deviation value in the historical monitoring period; Grid harmonic tolerance threshold = maximum grid harmonic level + a*grid harmonic standard deviation value in the historical monitoring period; Where a represents a predefined safety factor.

[0033] It should be added that the following steps are also included before determining the maximum number of electric vehicle charging piles that can be connected to the power grid in each future monitoring time period: The grid harmonic tolerance threshold is compared with the comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring period. If the comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in a future monitoring period is greater than the grid harmonic tolerance threshold, it indicates that the current state of the grid is not suitable for connecting more electric vehicle charging piles; If the comprehensive evaluation values ​​of the grid harmonic levels under the set number of electric vehicle charging piles in a future monitoring period are all less than or equal to the grid harmonic tolerance threshold, the next step is executed; If in a future monitoring time period, there is both a comprehensive evaluation value of the grid harmonic level under a certain set number of electric vehicle charging piles that is greater than or equal to the grid harmonic tolerance threshold and a comprehensive evaluation value of the grid harmonic level under a certain set number of electric vehicle charging piles that is less than the grid harmonic tolerance threshold, then the maximum set number of electric vehicle charging piles with a comprehensive evaluation value of the grid harmonic level less than the grid harmonic tolerance threshold is selected as the maximum number of electric vehicle charging piles that can be connected to the grid in each future monitoring time period.

[0034] It should be added that the maximum number of electric vehicle charging piles that can be connected to the power grid in each future monitoring period is determined by the following process: The possible harmonic generation value of a single charging pile is extracted from the reference information database, and the comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period is subtracted from the set grid harmonic tolerance threshold. The subtraction result is then divided by the possible harmonic generation value of a single charging pile, and the maximum number of electric vehicle charging piles that can be connected to the grid in each future monitoring time period is obtained.

[0035] Step S4: output the maximum number of electric vehicle charging piles that can be connected to the power grid in each future monitoring time period to an external device for further operation processing.

[0036] Example 2 According to an exemplary embodiment, a device for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics includes: an electronic device and a computer-readable storage medium; Figure 2 It is a structural schematic diagram of a device for analyzing the impact of multi-access electric vehicle charging piles on power grid harmonics provided in an embodiment of the present application. The device may have relatively large differences due to different configurations or performances, and can include one or more processors (Central Processing Units, CPU) and one or more memories, wherein at least one computer program is stored in the memory, and the at least one computer program is loaded and executed by the processor to implement the above-mentioned method for analyzing the impact of multi-access electric vehicle charging piles on power grid harmonics.

[0037] The electronic device comprises a processor, a memory and a communication bus, wherein the memory stores a computer-readable program executable by the processor; The communication bus realizes the connection and communication between the processor and the memory; The processor implements the above-mentioned method for analyzing the influence of multiple access electric vehicle charging piles on power grid harmonics by calling the computer program stored in the memory and executing the computer readable program; The computer-readable storage medium stores one or more programs. When executed on an electronic device, the one or more programs can be executed by one or more processors, providing a user input interface to implement the above-mentioned method for analyzing the impact of multi-access electric vehicle charging piles on power grid harmonics.

[0038] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0039] It should be understood that determining B based on A does not mean determining B only based on A. B can also be determined based on A and / or other information.

[0040] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0041] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for analyzing the impact of multiple electric vehicle charging piles on power grid harmonics, characterized in that: The following steps are involved: Step S1, setting a monitoring time period, simulating multiple electric vehicle charging piles to be connected to the power grid at a set number, and collecting power grid load data at each set number of electric vehicle charging piles in the current monitoring time period; Step S2: Based on the grid load data, predict and analyze the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period; Step S3: setting a grid harmonic tolerance threshold, and determining the maximum number of electric vehicle charging piles that can be connected to the grid in each future monitoring time period based on the grid harmonic tolerance threshold and the prediction analysis results of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period; Step S4: output the maximum number of electric vehicle charging piles that can be connected to the power grid in each future monitoring time period to an external device for further operation processing.

2. The method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics according to claim 1 is characterized in that: Simulate multiple electric vehicle charging piles connected to the grid at a set number. The specific simulation process is as follows: The maximum carrying capacity of the power grid, the maximum charging power value of electric vehicles, and the total number of target electric vehicle charging piles in the current monitoring time period are obtained from the reference information library, and they are respectively imported into the simulation model of the power system analysis software. At the beginning of the simulation, the status of the charging piles is initialized to all idle, and the current load of the power grid is set to zero. The simulation is performed according to time steps: at each time point, the newly arrived electric vehicles are checked and the charging piles are assigned, the status of the charging electric vehicles is updated, the charging piles of the electric vehicles that have completed charging are released, and the status of the charging piles and the power grid load data are updated.

3. The method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics according to claim 1 is characterized in that: In step S1, the grid load data under each set number of electric vehicle charging piles in the current monitoring time period includes harmonic distortion rate, K factor and harmonic power factor.

4. The method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics according to claim 3 is characterized in that: Collect the grid load data under each set number of electric vehicle charging piles in the current monitoring time period. The specific collection process is as follows: According to the simulation model of the power system analysis software, the current value corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period is obtained, and the collected time series data is converted using the FFT algorithm, thereby converting it from the time domain to the frequency domain, thereby converting each monitoring time point in the current monitoring time period into each frequency point in the current monitoring time period, and further calculating the current peak amplitude of each harmonic component corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period , j represents the number of each monitoring time point, j=1,2,...i, c represents the number of each set number of electric vehicle charging piles, c=1,2,...f, v represents the number of each harmonic component, v=1,2,...d, thus obtaining the current effective value of each harmonic component under each set number of electric vehicle charging piles at each monitoring time point in the current monitoring time period ; The current peak amplitude of each harmonic component at each monitoring time point corresponding to each set number of electric vehicle charging piles in the current monitoring time period , They respectively represent the real part and imaginary part of the complex number corresponding to the jth monitoring time point in the current monitoring time period corresponding to the vth harmonic component under the cth set number of electric vehicle charging piles in the FFT result; Finally, the harmonic distortion rate under each set number of electric vehicle charging piles in the current monitoring time period is calculated through the THD harmonic distortion rate calculation formula; Comprehensive analysis obtains the K coefficient for each set number of electric vehicle charging piles during the current monitoring period , v represents the order of each harmonic component, It is the effective value of the fundamental current under the c-th set number of electric vehicle charging piles at the j-th monitoring time point in the current monitoring time period.

5. The method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics according to claim 4 is characterized in that: Collect the grid load data under each set number of electric vehicle charging piles in the current monitoring time period. The specific collection process also includes the following steps: According to the simulation model of the power system analysis software, the current value corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring period is obtained and voltage value ; Calculate the active power corresponding to each set number of electric vehicle charging piles at each monitoring time point in the current monitoring period ; Calculate the harmonic reactive power at each monitoring time point corresponding to each set number of electric vehicle charging piles during the current monitoring period ,in It represents the voltage effective value of the vth harmonic component at the jth monitoring time point corresponding to the cth set number of electric vehicle charging piles in the current monitoring period, Represents the phase difference between the voltage and current of the vth harmonic component; Calculate the distortion power at each monitoring time point corresponding to each set number of electric vehicle charging piles during the current monitoring period ,in They represent the apparent power and reactive power at the cth set number of electric vehicle charging piles corresponding to the jth monitoring time point in the current monitoring period respectively; Comprehensively calculate the harmonic power factor under each set number of electric vehicle charging piles in the current monitoring time period .

6. The method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics according to claim 3 is characterized in that: In step S2, the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period is predicted and analyzed. The specific analysis process is as follows: Extracting grid load data for each set number of electric vehicle charging piles in each historical monitoring period from a reference information database; According to the harmonic distortion rate of each set number of electric vehicle charging piles in the current monitoring time period And the harmonic distortion rate under each set number of electric vehicle charging piles in each historical monitoring period , m represents the number of each historical monitoring time period, m=1,2,...q; The harmonic distortion rates under each set number of electric vehicle charging piles in each historical monitoring period and the harmonic distortion rates under each set number of electric vehicle charging piles in the current monitoring period are arranged in sequence according to the time series, thereby obtaining the set of harmonic distortion rates under each set number of electric vehicle charging piles in the monitoring period. ; The harmonic distortion rate of each set number of electric vehicle charging piles in the first future monitoring period is calculated based on the ARIMA model. , where c represents the set constant term, is the coefficient of the autoregressive term, The harmonic distortion rate under the set number of electric vehicle charging piles in the qth historical monitoring period and the cth historical monitoring period, respectively, calculating a correction factor for a predetermined error; According to the calculation method of the harmonic distortion rate under each set number of electric vehicle charging piles in the first future monitoring time period, the harmonic distortion rate under each set number of electric vehicle charging piles in the second future monitoring time period, the third future monitoring time period to the nth future monitoring time period is calculated in the same way, and the harmonic distortion rate under each set number of electric vehicle charging piles in each future monitoring time period is obtained by integrating them. , n represents the number of each future monitoring time period, n=1,2,...p; Based on the harmonic distortion rate under the set number of electric vehicle charging piles in each future monitoring period, the K coefficient under the set number of electric vehicle charging piles in each future monitoring period is calculated in the same way. Harmonic Power Factor ; The harmonic distortion rate, K factor and harmonic power factor under each set number of electric vehicle charging piles in each future monitoring period are normalized, and a comprehensive analysis is performed to obtain a comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring period. , b1, b2 and b3 represent the weight factors of the harmonic level corresponding to the set harmonic distortion rate, K factor and harmonic power factor, respectively, and b1+b2+b3=1, They are respectively expressed as the harmonic distortion rate, K factor and harmonic power factor under the cth set number of electric vehicle charging piles in the nth future monitoring period after the standard.

7. The method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics according to claim 1, characterized in that: To set the grid harmonic tolerance threshold, the specific process is as follows: Filter out the power grid harmonic level values ​​in each historical monitoring period from the reference information database, arrange them in descending order, and obtain the maximum value of the power grid harmonic level; The power grid harmonic level value in each historical monitoring period is calculated to obtain the power grid harmonic standard deviation value in the historical monitoring period; Grid harmonic tolerance threshold = maximum grid harmonic level + a* grid harmonic standard deviation value in the historical monitoring period; Where a represents a predefined safety factor.

8. The method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics according to claim 1, characterized in that: The following steps are also included before determining the maximum number of electric vehicle charging piles that can be connected to the power grid in each future monitoring time period: The grid harmonic tolerance threshold is compared with the comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring period. If the comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in a future monitoring period is greater than the grid harmonic tolerance threshold, it indicates that the current state of the grid is not suitable for connecting more electric vehicle charging piles; If the comprehensive evaluation values ​​of the grid harmonic levels under the set number of electric vehicle charging piles in a future monitoring period are all less than or equal to the grid harmonic tolerance threshold, the next step is executed; If in a future monitoring time period, there is both a comprehensive evaluation value of the grid harmonic level under a certain set number of electric vehicle charging piles that is greater than or equal to the grid harmonic tolerance threshold and a comprehensive evaluation value of the grid harmonic level under a certain set number of electric vehicle charging piles that is less than the grid harmonic tolerance threshold, then the maximum set number of electric vehicle charging piles with a comprehensive evaluation value of the grid harmonic level less than the grid harmonic tolerance threshold is selected as the maximum number of electric vehicle charging piles that can be connected to the grid in each future monitoring time period.

9. The method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics according to claim 8, characterized in that: Determine the maximum number of electric vehicle charging piles that can be connected to the grid in each future monitoring period. The determination process is as follows: The possible harmonic generation value of a single charging pile is extracted from the reference information database, and the comprehensive evaluation value of the grid harmonic level under each set number of electric vehicle charging piles in each future monitoring time period is subtracted from the set grid harmonic tolerance threshold. The subtraction result is then divided by the possible harmonic generation value of a single charging pile, and the maximum number of electric vehicle charging piles that can be connected to the grid in each future monitoring time period is obtained.

10. An analysis device for the impact of multiple electric vehicle charging piles on power grid harmonics, characterized in that: It is implemented based on a method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics as described in any one of claims 1 to 9, and includes an electronic device and a computer-readable storage medium; The electronic device comprises a processor, a memory and a communication bus, wherein the memory stores a computer-readable program executable by the processor; The communication bus realizes the connection and communication between the processor and the memory; When the processor executes the computer-readable program, the processor implements the steps in the method for analyzing the impact of multiple access electric vehicle charging piles on power grid harmonics as described in any one of claims 1 to 9; The computer-readable storage medium stores one or more programs, and the one or more programs can be executed by one or more processors to implement the steps in the method for analyzing the impact of multi-access electric vehicle charging piles on power grid harmonics as described in any one of claims 1-9.

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