Zero-crossing-point accurate detection method for AC power-grid voltage signals

A technology of zero-crossing detection and AC power grid, which is applied in the field of phase-locking

Inactive Publication Date: 2014-10-08
XI'AN POLYTECHNIC UNIVERSITY
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  • Abstract
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  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to provide an accurate detection method for the zero-crossing point of the AC voltage signal, which solves the problems of zero-point drift and phase delay caused by the hardware detection circuit and software algorithm when detecting the zero-crossing point of the AC voltage signal, and improves the accuracy of the actual signal. Accuracy and rapidity of frequency, phase and amplitude information detection

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  • Zero-crossing-point accurate detection method for AC power-grid voltage signals
  • Zero-crossing-point accurate detection method for AC power-grid voltage signals
  • Zero-crossing-point accurate detection method for AC power-grid voltage signals

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Embodiment

[0184] In order to effectively filter the harmonics and random noise at the zero-crossing point of the grid voltage, for example, take the filter time constant RC as 300μs, and according to step 1.1, the digital quantity corresponding to the delay caused by the voltage detection hardware circuit for zero-crossing detection is t 1 =300×10 -6 ×2 18 ≈79;

[0185] If the STM32F103VBT6 micro-control chip with a main frequency of 72MHz is used for ADC conversion, and the number of sampling points in one power frequency cycle of the rated 220V grid voltage is set to N=400; the 24 frequency division of the system clock frequency of the ARM chip is used as the general-purpose timer TIMx Clock frequency, set the counting mode to count up, and the period value of the auto-reload register is 65535; considering the accuracy of the program algorithm, set the peak value of 455V AC voltage to correspond to 12-bit ADC, then according to step 1.2, it can be obtained:

[0186]

[0187]

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Abstract

The invention discloses a zero-crossing-point accurate detection method for AC voltage signals. The method includes the following steps: firstly selecting a comparatively large hardware filtering time constant to ensure that harmonic waves and random noises which may be included in the AC voltage signals can be filtered comparatively well; using large-time-constant software PQ filtering to extract and eliminate DC drift generated by software and hardware; setting a software judgment advancing quantity so as to offset zero-crossing-point delay caused by hardware filtering; accurately calculating random errors t caused by sampling intervals; and at last, using capture and comparison functions of an embedded microcontroller to realize accurate information of an AC voltage frequency and phase so that accurate phase locking of the AC signals can be realized. The detection method solves a problem of zero drift and phase delay caused by a hardware detection circuit and a software algorithm when zero-crossing-point detection is carried out on the AC voltage signals.

Description

technical field [0001] The invention belongs to the technical field of phase-locking methods, and relates to a method for accurately detecting a zero-crossing point of an AC grid voltage signal. technical background [0002] Fast and accurate acquisition of grid voltage or current phase information is of great significance to the steady-state, dynamic performance and safe operation of various grid-connected converters. In the 1930s, the concept of phase-locking technology was jointly proposed by scholars Appleton and Bellesciz, and was first applied to the synchronous reception of radio signals. Subsequently, phase-locked technology is widely used in industrial fields, such as: motor control systems, power quality control systems, distributed power generation systems, active filters and static var compensators and other power electronic conversion systems. How to improve the speed and accuracy of PLL is an important research topic. [0003] At present, the widely researche...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R19/175G01R19/25
Inventor 陈增禄赵乾坤夏冠亚程新红
Owner XI'AN POLYTECHNIC UNIVERSITY
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