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Power quality monitoring method

A power quality monitoring and voltage technology, applied in the direction of measuring electrical variables, measuring electricity, measuring devices, etc., can solve the problems of power quality problems, hazards, and insufficient comprehensiveness of power quality problems, achieve good real-time performance and follow-up, and improve cost performance. The effect of reducing the amount of calculation

Active Publication Date: 2013-10-16
SHENZHEN KANGBIDA CONTROL TECH
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In daily work, the grasp of power quality problems is not comprehensive enough, mainly focusing on voltage qualification rate and harmonics, and insufficient awareness of power quality problems and hazards caused by voltage sags and instantaneous power supply interruptions

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Embodiment 1, according to GB / T12325-2008 and IEC_61000-4-30_2003, the basic measurement time window for obtaining the effective value of the voltage is 10 cycles, and the average value of the effective value of the voltage is calculated without overlapping consecutive measurements, and finally the voltage deviation is calculated. Monitoring range: 10~150% Udin (declared input voltage,) Monitoring accuracy: ±0.1% Output: actual voltage value, voltage deviation, voltage qualified rate Voltage effective value calculation, because the effective value of half cycle is calculated in real time. Or calculate according to the requirements of GB / T12325-2008, using the method of calculating the RMS of the effective value of the 20 half-cycle sliding windows within the 10circle. Calculation cycle: 10circle 3s

Embodiment 2

[0041] Embodiment 2, monitoring range: 42.5-57.5Hz (the actual range of the device is 42-58Hz, leaving a certain margin); monitoring accuracy: ±0.01Hz (0.005Hz); output: actual frequency, frequency deviation, frequency pass rate; algorithm : GB / T_15945-2008 recommended method: take the ratio of the integer cycles counted in 1s, 3s or 10s intervals to the accumulated time of integer cycles. IEC_61000-4-30_2003: A system frequency value is given at intervals of 10s (±20ms), and the time intervals are not allowed to overlap; the number of full cycles and their time within 10s are accumulated, and the system frequency is calculated using the number of full cycles / time. Measurement method: introduce a square wave signal synchronized with the voltage signal into GPIO, its rising edge or falling edge triggers an interrupt, and at the same time counts through the counter, calculates the frequency at the corresponding time interval, and calculates the frequency Among them: f is the ca...

Embodiment 3

[0042] Embodiment 3, the standard definitions of harmonics and inter-harmonics are as follows, harmonics and inter-harmonics are monitored, 512 / 1024 points are sampled per cycle, and 5120-point FFT based on prime factor algorithm is performed with 10 cycles as a time window, and the frequency resolution is Frequency rate is 5Hz (fundamental wave 50Hz), accurate measurement of harmonic components, phase angle, total harmonic distortion rate, even harmonic distortion rate, odd harmonic distortion rate from 1 to 63 order (inter) harmonic components; resolution from 5Hz The calculation from rate harmonic components to harmonics and inter-harmonics uses a subgroup algorithm to reduce aliasing errors and spectrum leakage. For example, the second inter-harmonic is obtained by calculating the square sum of the 95Hz / 100Hz / 105Hz components. . Input volume: 512 sampling points of 10 / 20 cycles Output volume: within 0~639 / 1279 times, the minimum frequency resolution corresponding to 5120 / 1...

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Abstract

The invention discloses a power quality monitoring method. A FPGA is employed in the method to realize zero-crossing detection function and compared with traditional voltage-controlled oscillators, the method exhibits better real-time performance and following performance. On frequency measurement and sampling control, three-phase voltage signal is introduced as a standard of the frequency measurement and the sampling control so that, compared with one-phase voltage signal introduced as the standard, the method is more reliable and flexible; that software controls sample interval is as a supplement of hardware sampling control, so that sampling accuracy is improved; on algorithm input points, accuracy requirement of the algorithm and the calculated quantity are balanced; and under the condition that accuracy is guaranteed, calculated quantity is lessened, so that cost performance of the actual device is improved.

Description

technical field [0001] The invention relates to the field of smart grids, in particular to a method for monitoring power quality in the grid. Background technique [0002] With the economic development and the wide application of high-tech equipment, users have higher requirements on the quality of power supply, making the problem of power quality increasingly prominent, which has attracted the attention of the majority of electric power workers. [0003] The primary problem of power quality is voltage sag, which should be the focus of research and solution. More than 90% of user complaints about power quality problems are caused by voltage dips. [0004] Power quality issues have been mentioned in the agenda of power companies in some economically developed countries (or regions). In comparison, in my country, there is a gap in the understanding of power quality problems and the practice of measures, and there is no time to carry out detailed power quality management. In...

Claims

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Application Information

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IPC IPC(8): G01R31/00G05B19/042
Inventor 丁建义林峰平陈宜彬张孝山梁启权李秀芳杨德勇晏文龙
Owner SHENZHEN KANGBIDA CONTROL TECH
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