CN-121978389-A - Sampling method, system and device

CN121978389ACN 121978389 ACN121978389 ACN 121978389ACN-121978389-A

Abstract

The invention discloses a sampling method, a system and a device, wherein the method comprises the steps of converting an alternating voltage/current signal of an active power distribution network in a current period into a square wave signal in the same frequency in the current period, generating sampling pulses in the same phase interval as the square wave signal in the current period according to the square wave signal in the current period, a high-frequency stable pulse of a local clock and the frequency of the square wave signal in the previous period, sampling the square wave signal in the current period at the same phase interval according to the sampling pulses, obtaining the sampling signals in the current period, and correcting phase angles of the sampling signals according to the time information of the time mark pulses in the current period and the time information of the sampling pulses in the current period. The invention not only can track the frequency of the sampled signal and correct the phase angle of the sampled signal, but also can realize high-precision synchronous sampling on the premise of not adding a large amount of extra calculated quantity, and can improve the monitoring and control performance of the feeder terminal of the active power distribution network.

Inventors

LIU SHEN
WANG YANPENG
YAN QI
LIANG WEICHEN
ZHAO LIPING
LI RUIRUI
JI YINGDONG
CHANG XIAOXU
QI XIAOXIA
WANG YUMENG
WU SIXUE

Assignees

国网冀北电力有限公司张家口供电公司

Dates

Publication Date: 20260505
Application Date: 20251127

Claims (8)

1. A method of sampling comprising: converting the alternating-current voltage/current signal of the active power distribution network of the period into a square wave signal of the period with the same frequency; Generating sampling pulses with equal phase intervals at the same frequency as the periodic square wave signal according to the periodic square wave signal, the high-frequency stable pulse of the local clock and the frequency of the last periodic square wave signal; Sampling the square wave signal in the current period at equal phase intervals according to the sampling pulse to obtain an alternating voltage/current sampling signal; And carrying out phase angle correction on the sampling signal according to the time information of the time mark pulse and the sampling pulse of the local clock at equal time intervals.
2. The method of claim 1, wherein converting the periodic ac voltage/current signal of the active power distribution network to a same frequency periodic square wave signal comprises: Carrying out band-pass filtering on the alternating-current voltage/current signals of the active power distribution network in the period to obtain fundamental wave signals; and the fundamental wave signal is converted into a same-frequency periodic square wave signal by adopting a zero-crossing triggering mode.
3. The method of claim 1, wherein generating equally phase-spaced sampling pulses of the same frequency as the current periodic square wave signal based on the current periodic square wave signal, the high frequency stabilization pulse of the local clock, and the frequency of the previous periodic square wave signal, comprises: counting the number of pulses between adjacent rising edges of the square wave signal in the current period by taking the high-frequency stable pulse as a reference, and calculating the period of the square wave signal in the current period according to the number of pulses and the period of the high-frequency stable pulse; Determining the total number of high-frequency stable pulses in the previous cycle square wave signal according to the frequency of the previous cycle square wave signal, and calculating the sampling pulse generation count value of the current cycle according to the total number of the high-frequency stable pulses in the previous cycle square wave signal and the preset number of sampling points of each cycle, wherein the sampling pulse generation count value of the current cycle is the count value of the high-frequency stable pulse corresponding to each equal division interval after the equal division of the number of sampling points of each cycle between the adjacent rising edges of the current cycle square wave signal according to the preset number of sampling points of each cycle; And generating a count value and a high-frequency stable pulse according to the sampling pulse of the period, and generating sampling pulses with equal phase intervals in the same frequency as the square wave signal of the period, wherein in the process of generating the sampling pulses, the high-frequency stable pulse is used as a reference to accumulate and count, and one sampling pulse is generated when the count value is generated every time the sampling pulse is full.
4. The method of claim 1, wherein phase angle correction of the sampled signal based on the time information of the time-stamped pulses and the sampling pulses at the time interval of the local clock comprises: Calculating the time difference between the sampling time in the sampling pulse and the nearest time mark in the time mark pulse, wherein the nearest time mark is the time mark nearest to the sampling time; performing linear interpolation on the sampling signal according to the time difference to obtain a new sampling signal, wherein in the new sampling signal, the sampling value is aligned with the time of the corresponding time mark pulse; and according to the time difference, adopting a Taylor series expansion method to correct the phase angle of the new sampling signal.
5. The method of claim 4, wherein the phase angle correction formula is: ; In the formula, In order to correct the phase angle after the correction, For the phase angle before correction, j is the imaginary unit, f is the nominal frequency, Δt is the time difference, N is the data window length, T_s is the sampling period, For the phase angle of the kth sample point, Is the phase angle of the kth-N sampling point.
6. A sampling system, comprising: the conditioning module converts the alternating voltage/current signal of the active power distribution network in the period into a square wave signal in the period of the same frequency; The sampling pulse generation module generates sampling pulses with equal phase intervals in the same frequency as the periodic square wave signal according to the periodic square wave signal, the high-frequency stable pulse of the local clock and the frequency of the last periodic square wave signal; The sampling module is used for sampling the periodic square wave signal at equal phase intervals according to the sampling pulse to obtain a sampling signal; and the correction module is used for carrying out phase angle correction on the sampling signal according to the time information of the time mark pulse and the sampling pulse of the local clock at the equal time interval.
7. The sampling device is characterized by comprising a conditioning circuit, a first processor, a second processor and a sampling circuit; The conditioning circuit converts the alternating voltage/current signal of the active power distribution network in the period into a square wave signal in the period with the same frequency, and transmits the square wave signal to the first processor and the sampling circuit; the first processor realizes a local clock according to clock source time information, generates sampling pulses with equal phase intervals and same frequency as the periodic square wave signal according to the periodic square wave signal, high-frequency stable pulse of the local clock and the frequency of the last periodic square wave signal, acquires time information of the sampling pulses according to the sampling pulses, sends the sampling pulses to the sampling circuit, and sends time mark pulses with equal time intervals and time information of the sampling pulses of the local clock to the second processor; The sampling circuit samples the periodic square wave signal at equal phase intervals according to the sampling pulse, and sends the obtained sampling signal to the second processor; The second processor phase angle corrects the sampled signal based on the time information of the time stamp pulses and the sampled pulses at the time interval of the local clock.
8. The device according to claim 7, wherein the conditioning circuit comprises a band-pass filter and a shaping circuit which are sequentially connected in series, the band-pass filter carries out band-pass filtering on alternating voltage/current signals of the active power distribution network in the current period to obtain fundamental wave signals, and the shaping circuit converts the fundamental wave signals into current period square wave signals in the same frequency in a zero-crossing triggering mode.

Description

Sampling method, system and device Technical Field The invention relates to a sampling method, a sampling system and a sampling device, and belongs to the technical field of power system automation. Background In the operation of an active power distribution network, a novel feeder terminal needs to carry out synchronous phasor measurement, in the phasor calculation of the synchronous phasor measurement, a discrete Fourier transform method is widely applied, and a corresponding sampling mode comprises equal time interval sampling and equal phase interval sampling, but the former needs to prolong sampling time, increase sampling points and iterative operation to correct errors, the calculation is complex, the method is not suitable for dynamic signals, singlechips and digital signal processors, and the latter can track the frequency of a measured signal, but has the problem that the uniform time scale of the whole network does not correspond to the sampling moment of the phasor calculation, so that the phasor calculation errors are caused. Therefore, a new sampling method suitable for the novel feeder terminal of the active power distribution network is needed. Disclosure of Invention The invention provides a sampling method, a sampling system and a sampling device, which solve the problems disclosed in the background technology. According to one aspect of the present application, there is provided a sampling method comprising: converting the alternating-current voltage/current signal of the active power distribution network of the period into a square wave signal of the period with the same frequency; Generating sampling pulses with equal phase intervals at the same frequency as the periodic square wave signal according to the periodic square wave signal, the high-frequency stable pulse of the local clock and the frequency of the last periodic square wave signal; Sampling the square wave signal in the current period at equal phase intervals according to the sampling pulse to obtain a sampling signal; And carrying out phase angle correction on the sampling signal according to the time information of the time mark pulse and the sampling pulse of the local clock at equal time intervals. Further, converting the ac voltage/current signal of the active power distribution network of the present period into a square wave signal of the present period with the same frequency, including: Carrying out band-pass filtering on the alternating-current voltage/current signals of the active power distribution network in the period to obtain fundamental wave signals; and the fundamental wave signal is converted into a same-frequency periodic square wave signal by adopting a zero-crossing triggering mode. Further, according to the square wave signal of the present period, the high-frequency stable pulse of the local clock and the frequency of the square wave signal of the previous period, the sampling pulse with equal phase interval and same frequency as the square wave signal of the present period is generated, which comprises: counting the number of pulses between adjacent rising edges of the square wave signal in the current period by taking the high-frequency stable pulse as a reference, and calculating the period of the square wave signal in the current period according to the number of pulses and the period of the high-frequency stable pulse; Determining the total number of high-frequency stable pulses in the previous cycle square wave signal according to the frequency of the previous cycle square wave signal, and calculating the sampling pulse generation count value of the current cycle according to the total number of the high-frequency stable pulses in the previous cycle square wave signal and the preset number of sampling points of each cycle, wherein the sampling pulse generation count value of the current cycle is the count value of the high-frequency stable pulse corresponding to each equal division interval after the equal division of the number of sampling points of each cycle between the adjacent rising edges of the current cycle square wave signal according to the preset number of sampling points of each cycle; And generating a count value and a high-frequency stable pulse according to the sampling pulse of the period, and generating sampling pulses with equal phase intervals in the same frequency as the square wave signal of the period, wherein in the process of generating the sampling pulses, the high-frequency stable pulse is used as a reference to accumulate and count, and one sampling pulse is generated when the count value is generated every time the sampling pulse is full. Further, performing phase angle correction on the sampled signal according to the time information of the time scale pulse and the sampling pulse of the local clock, including: Calculating the time difference between the sampling time in the sampling pulse and the nearest time mark in the time mark pulse, wherein the nearest time mark