A Fourier transform-based ATSE power supply harmonic analysis method

Abstract

The present application relates to a kind of Fourier transform-based ATSE power harmonic analysis method, comprising the following steps: collecting each AD data, each AD value is processed by central axis zeroing;After each AD value processed by central axis zeroing, Fourier transform calculation is carried out, and the harmonic content of each waveform is obtained;According to each harmonic content, total harmonic content is obtained;According to total wave effective value and total harmonic content, further obtain fundamental effective value;Through the fundamental effective value and each harmonic content, control logic analysis power state is assisted.The present application is based on Fourier transform harmonic analysis method, helps automatic transfer switch to analyze the harmonic content of current power, so that controller more comprehensive analysis power state, more suitable switching mode is selected according to load condition, further improve the safety and reliability of dual power automatic transfer switch, maintain the normal operation of entire power system, protect electrical equipment and reduce power loss.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of three-phase power supply harmonic analysis monitoring, and particularly relates to an ATSE power supply harmonic analysis method based on Fourier transform. BACKGROUND

[0002] With the increasing demand for power supply continuity and reliability, important places such as general hospitals, banks, airports, wharfs, fire departments and military departments that do not allow power failure all require at least two power supplies to ensure power supply continuity, that is, a dual power supply system is used, so it is crucial for the dual power supply controller to detect whether the two power supplies of the power supply system are stable and continuous. The dual power supply automatic transfer switch products widely used in the market do not have a power supply harmonic analysis function, resulting in a significant deviation in the calculation results of the sampling loop of the controller, affecting the accuracy of the analysis of the controller, and further causing great harm to the safe and reliable operation of the power equipment. SUMMARY

[0003] The present application solves the technical problems in the prior art and provides an ATSE power supply harmonic analysis method based on Fourier transform, which helps the automatic transfer switch to analyze the harmonic content of the current power supply and further improves the accuracy and reliability of the power supply fault analysis of the automatic transfer switch.

[0004] The present application is implemented by the following technical solutions:

[0005] An ATSE power supply harmonic analysis method based on Fourier transform comprises the following steps: S1. Collecting AD data of each channel and performing central axis zero processing on the AD values of each channel; S2. Performing Fourier transform calculation on the AD values of each channel after the central axis zero processing to obtain the harmonic content of each channel; S3. Obtaining the total harmonic content according to the harmonic content; S4. Further obtaining the fundamental wave effective value according to the total wave effective value and the total harmonic content; and S5. Assisting the control logic to analyze the power supply state through the fundamental wave effective value and the harmonic content.

[0006] According to the above technical solution, preferably, the AD data of each channel in step S1 comprises three-phase voltage AD data of the main power supply, three-phase voltage AD data of the backup power supply and three-phase current AD data of the load.

[0007] According to the above technical solution, preferably, the central axis zero processing in step S1 comprises: calculating the mean value of the AD data of each channel; and subtracting the mean value from each AD value to make the central axis of the AD value return to the 0 coordinate axis.

[0008] According to the above technical solution, preferably, between step S2 and step S3, there is further: correcting the harmonic content.

[0009] According to the technical scheme, preferably, the controller comprises a sampling circuit for collecting the AD data.

[0010] According to the technical scheme, preferably, the relationship between the sampling point of each AD data and the highest order measurable harmonic is 2:1.

[0011] The present application has the following advantages:

[0012] The harmonic analysis method based on Fourier transform of the present application only needs to collect three-phase power supply three-phase voltage to be implemented, which greatly saves the cost and complexity of the hardware circuit, helps the automatic transfer switch to analyze the harmonic content of the current power supply, so that the controller can comprehensively analyze the power supply state, select a more appropriate switching mode according to the load condition, further improve the safety and reliability of the dual power automatic transfer switch, maintain the normal operation of the entire power system, protect the power equipment and reduce the power loss. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a schematic diagram of the circuit connection of the present application.

[0014] Figure 2 is a schematic diagram of the method flow of the present application.

[0015] Figure 3 is a phase voltage waveform diagram under the condition of no harmonic.

[0016] Figure 4 is a phase voltage waveform diagram under the condition of 30% third harmonic content.

[0017] Figure 5 is a phase voltage waveform diagram under the condition of 30% fifth harmonic content. DETAILED DESCRIPTION

[0018] In order to make the person skilled in the art better understand the technical scheme of the present application, the present application will be further described in detail below in combination with the drawings and the best embodiment. All other embodiments obtained by the person skilled in the art without creative labor on the basis of the embodiments in the application belong to the protection scope of the application.

[0019] In the description of the application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation of the application.

[0020] The three-phase voltage waveform when the power supply is normal is as follows Figure 3As shown, the power supply is normal, and the waveform is a harmonic-free waveform, and the waveform presents a regular sine waveform, and the phase angle is balanced at about 120°, and the effective value of the power supply voltage and current obtained by using the traditional root mean square algorithm is very accurate, and the reliability of the automatic transfer switch function can be ensured. Figure 4 As shown, the power supply contains 30% of the third harmonic, and the phase voltage waveform of the fault phase power supply is obviously distorted, and the effective value changes obviously, and this condition can cause the calculation result of the controller sampling loop to deviate obviously, and affect the accuracy of the controller analysis. Figure 5 As shown, the power supply contains 30% of the fifth harmonic, and the phase voltage waveform is more seriously distorted, and the effective value deviation is larger. Therefore, the power supply is analyzed for harmonics, the fundamental content and the content of each harmonic are determined, the controller can analyze the power supply state more comprehensively, and a more suitable switching mode can be selected according to the load condition.

[0021] The circuit connection diagram of the application is shown in the figure. Figure 1 The controller collects AD data of each phase of the three-phase power supply, and the lower end of the power supply is connected with a load, as shown in the figure. Figure 2 The ATSE power supply harmonic analysis method based on Fourier transform includes the following steps:

[0022] S11. Collect each AD data, and each AD data includes three-phase voltage AD data of the main power supply, three-phase voltage AD data of the standby power supply and three-phase current AD data of the load, and 64 sampling points per cycle are collected, so that the highest 31 harmonics can be analyzed, and if higher harmonic content is to be analyzed, the number of sampling points can be increased, and the relationship between the sampling points and the highest measurable harmonic is 2:1. In addition, in this example, data collection is realized by the sampling circuit of the controller, and no additional hardware circuit needs to be added to meet the reliable monitoring of the power supply harmonic content, so that the method can be used for product upgrading at no cost, and only the software method needs to be updated, and the product development cycle can be effectively shortened.

[0023] S12. Calculate the average of each AD data, and subtract the average from each AD value, so that the AD value is returned to the 0 coordinate axis, and the central axis zero processing of each AD value is completed.

[0024] S21. Fourier transform is performed on each AD value after the central axis zero processing. The content of each harmonic of each waveform is calculated and obtained.

[0025] S22. Correct the content of each harmonic, and the corrected harmonic content is H n = h n *K n , wherein h n is the current content, K n is the correction coefficient of the corresponding harmonic, and H nTo correct the harmonic content.

[0026] S3. Obtain the total harmonic content according to the corrected harmonic content

[0027] S4. Obtain the total wave effective value through root mean square calculation According to the total wave effective value V rms And the total harmonic content H total , further obtain the fundamental wave effective value

[0028] S5. Through the fundamental wave effective value and each harmonic content, assist the control logic analysis, so that the controller more comprehensive analysis of power supply state, select more appropriate switching mode for load conditions.

[0029] The present application is based on the Fourier transform harmonic analysis method, only need to collect three-phase power three-way phase voltage can be implemented, greatly saves the cost and complexity of hardware circuit, help automatic transfer switch analysis of the current power harmonic content, so that the controller more comprehensive analysis of power supply state, select more appropriate switching mode for load conditions, further improve the safety and reliability of double power automatic transfer switch, maintain the normal operation of the entire power system, protect the electrical equipment and reduce power loss.

[0030] The above only is the preferred embodiment of the present application, it should be pointed out that, for those skilled in the technical field, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. An ATSE power supply harmonic analysis method based on Fourier transform, characterized in that, Includes the following steps: S1. The controller includes a sampling circuit for acquiring AD data from each channel and performing center axis zeroing processing on the AD values ​​of each channel; S2. Perform Fourier transform calculations on the AD values ​​of each channel after the central axis zeroing process to obtain the harmonic content of each waveform, specifically including: S21. Perform Fourier transform on each AD value after the central axis zeroing process. Calculate and obtain the harmonic content of each waveform; S22. Correct the harmonic content of each order, i.e., the corrected harmonic content is H. n =h n *K n , where h n For the current content, K n H is the correction factor for the corresponding harmonic order. n The corrected harmonic content; S3. Obtain the total harmonic content based on the content of each harmonic; S4. Based on the total effective value of the wave and the total harmonic content, further obtain the fundamental effective value; S5. The fundamental effective value and the content of each harmonic are used to assist the control logic in analyzing the power supply status.

2. The ATSE power supply harmonic analysis method based on Fourier transform according to claim 1, characterized in that, In step S1, the AD data for each channel includes the three-phase voltage AD data of the main power supply, the three-phase voltage AD data of the backup power supply, and the three-current AD data of the load.

3. The ATSE power supply harmonic analysis method based on Fourier transform according to claim 1 or 2, characterized in that, Step S1, "center axis zeroing process", includes: calculating the mean of each AD data; subtracting the mean from each AD value to bring the center axis of the AD value back to the 0 coordinate axis.

4. The ATSE power supply harmonic analysis method based on Fourier transform according to claim 1, characterized in that, Between step S2 and step S3, the method further includes: correcting the content of each harmonic.

5. The ATSE power supply harmonic analysis method based on Fourier transform according to claim 1, characterized in that, The ratio of the sampling points of each AD data stream to the highest measurable harmonic is 2:1.

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