CN-115639400-B - High-precision alternating-current electric energy metering method

Abstract

The invention discloses a high-precision alternating current electric energy metering method, which is characterized in that under higher sampling frequency, original data of a voltage signal and a current signal are obtained in a fixed frequency sampling mode, under a harmonic environment, a phase difference between the voltage signal and the current signal is obtained in a digital filtering and software zero crossing judging mode, and in a specific test time period, instantaneous power in a single sampling process is calculated through dot product and method, and the instantaneous power is accumulated periodically to be used as an active electric energy value. Under the condition of introducing a filtering link, the accuracy of zero crossing judgment can be improved, and the metering accuracy of active electric energy is further improved.

Inventors

• ZHANG JIE
• GAO RONGZHI
• LI SHENGPING
• BAI LIBING
• ZHOU QUAN
• CHEN CONG

Assignees

• 电子科技大学

Dates

Publication Date

20260505

Application Date

20220727

Claims (5)

1. 1. The high-precision alternating current energy metering method is characterized by comprising the following steps of: (1) Providing a sampling clock and a measuring range of a sampling channel by a control unit, setting the measuring range of the sampling channel to be 1.5 to 3 times of the current signal amplitude by a real-time feedback mode to ensure higher resolution, and then collecting voltage data and current data at a high sampling rate; (2) The collected voltage data and the collected current data are subjected to filtering treatment in a cascade connection mode of the low-pass filter and the high-pass filter; (3) Calculating a phase difference and a frequency value of the voltage data and the current data after the filtering processing by a zero crossing point comparator; (4) Calculating a phase difference by using the zero crossing point comparator for correcting instantaneous power, and using a frequency value for dynamically setting the sampling frequency of the system; (5) And calculating the active power value of the single sampling process through a dot-product accumulation formula.
2. 2. The high-precision alternating-current power metering method according to claim 1, wherein the sampling frequency of the high sampling rate is set to 200 times or more of the fundamental wave signal and is an integer multiple of the fundamental wave signal.
3. 3. The high-precision ac power metering method of claim 1, wherein the cut-off frequency of the low pass filter is lower than 49.75Hz and the cut-off frequency of the high pass filter is higher than 50.25Hz.
4. 4. The high-precision alternating-current power metering method according to claim 1, wherein the zero crossing point comparator is implemented by a software method and is calculated by averaging a plurality of test points.
5. 5. The method for measuring high-precision alternating-current electric energy according to claim 1, wherein the measuring method of the active electric energy value is that Wherein N is the total number of points recorded in a single sampling process, delta t is the sampling time interval, u (t i )、i(t i ) is an original voltage data point and an original current data point respectively, and K is an error correction coefficient.

Description

High-precision alternating-current electric energy metering method Technical Field The invention belongs to the technical field of power systems, and particularly relates to a high-precision alternating-current electric energy metering method. Background The accurate metering of the electric energy is an important guarantee of an electric power system and is a necessary technology for promoting the popularization of new energy markets. For AC power utilization, a typical electric energy metering method is an instantaneous power integration method, namely, firstly calculating the product of an instantaneous current value and an instantaneous voltage value, then combining the phase difference of the two values to correct, and finally accumulating and calculating the electric energy value. The accuracy of current signal and voltage signal measurement depends on the accuracy of the acquisition channel, the accuracy of phase difference measurement depends on the accuracy of a system timer, and when a zero crossing point detection method is adopted, signal noise fluctuation also affects phase judgment. The electronic electric energy metering device designed based on the principle has poor immunity to dynamic distortion, and the metering precision needs to be further improved. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a high-precision alternating current electric energy metering method, wherein in a specified test time period, the instantaneous power in a single sampling process is calculated through a dot product sum method, and the periodic accumulation is used as an active electric energy value. In order to achieve the above object, the invention provides a high-precision alternating current energy metering method, which is characterized by comprising the following steps: (1) Providing a sampling clock and a measuring range of a sampling channel by a control unit, setting the measuring range of the sampling channel to be 1.5 to 3 times of the current signal amplitude by a real-time feedback mode to ensure higher resolution, and then collecting voltage data and current data at a high sampling rate; (2) The collected voltage data and the collected current data are subjected to filtering treatment in a cascade connection mode of the low-pass filter and the high-pass filter; (3) Calculating a phase difference and a frequency value of the voltage data and the current data after the filtering processing by a zero crossing point comparator; (4) Calculating a phase difference by using the zero crossing point comparator for correcting instantaneous power, and using a frequency value for dynamically setting the sampling frequency of the system; (5) And calculating the active power value of the single sampling process through a dot-product accumulation formula. The invention aims at realizing the following steps: The invention relates to a high-precision alternating current electric energy metering method, which is characterized in that under higher sampling frequency, original data of a voltage signal and a current signal are obtained in a fixed frequency sampling mode, under a harmonic environment, a phase difference between the voltage signal and the current signal is obtained in a digital filtering and software zero crossing judgment mode, and in a specific test time period, the instantaneous power in a single sampling process is calculated through dot product and method, and the instantaneous power is accumulated periodically to be used as an active electric energy value. Under the condition of introducing a filtering link, the accuracy of zero crossing judgment can be improved, and the metering accuracy of active electric energy is further improved. Drawings FIG. 1 is a flow chart of a method for high precision AC power metering in accordance with the present invention; FIG. 2 is a schematic diagram of the system architecture of the present invention for a specific embodiment; fig. 3 shows the waveform effects before and after the digital filter bank operation. Detailed Description The following description of the embodiments of the invention is presented in conjunction with the accompanying drawings to provide a better understanding of the invention to those skilled in the art. It is to be expressly noted that in the description below, detailed descriptions of known functions and designs are omitted here as perhaps obscuring the present invention. Examples FIG. 1 is a flow chart of a method for measuring high-precision alternating current electric energy according to the invention. In this embodiment, referring to fig. 2, a high-precision ac power metering method is used for metering test cases of a three-phase four-wire system high-power loop, in which a voltage conditioning channel, an ADC sampling circuit and a current conditioning channel are used to implement a sampling process, a DSP unit is used to implement a digital filtering link and zero crossing poi