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Method for measuring fundamental frequency

A technology of fundamental frequency and measurement method, which is applied in the direction of frequency measurement device, frequency to phase shift conversion, etc., which can solve the problems of sensitivity to harmonics and noise, inability to obtain accurate frequency measurement results, etc.

Active Publication Date: 2010-04-21
HANGZHOU VANGO TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the algorithm is sensitive to harmonics and noise, and cannot obtain high-precision frequency measurement results under harsh conditions

Method used

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Embodiment Construction

[0032] The specific implementation manner of the method of the present invention will be described in detail below in conjunction with the application of the method of the present invention in the measurement of the fundamental frequency in the power system.

[0033] Embodiments of the method include the following steps:

[0034] 1): In the power system, China's national standard is f 0 =50Hz, it can be set as the initial value of the fundamental frequency of the actual grid, and the sampling frequency f of the analog-to-digital converter (hereinafter referred to as ADC) at the initial moment is set s =64×50Hz, and the expression of the input power grid signal in the discrete domain is:

[0035] v ( k ) = Σ n = 1 + ∞ A n cos ( 2 × ...

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Abstract

The invention relates to a measurement method of fundamental frequency and belongs to the field of composite signal processing, and the method comprises the following steps: the method acquires digital signals v(k) by implementing the input signal sampling with sampling frequency fs, which is N times an initial setting value f0 of the fundamental frequency f1, and constructs two orthogonal signalswith the frequency equal to an ideal value of the fundamental frequency of the input signal; the invention acquires a signal for low-pass filter processing by implementing multiplication between thetwo orthogonal signals and the input signal v(k), filters the high-frequency part of the signal and acquires the orthogonal signals which are related to the input signal, and then the method acquiresthephase position information in a time k which is related to the input signal through the arctangent computation, acquires the signal fundamental frequency by computing and transforming the differenceof the phase position information, and leads the system to be a closed loop feedback system by adjusting the sampling frequency fs according to the measurement result of the fundamental frequency,and consequently the fundamental frequency measured of a stable system is the final output result. The measurement method of fundamental frequency is characterized by good stability and high frequencymeasurement precision.

Description

technical field [0001] The invention belongs to the field of mixed signal processing, in particular to a fundamental wave frequency measurement method. Background technique [0002] In the power system, the measurement of the fundamental frequency of the power grid is one of the most basic measurement quantities. At present, the frequency measurement method with equal precision (multi-period synchronous measurement method) is widely used. This method has the characteristics of high measurement accuracy and the measurement accuracy does not change with the change of the measured signal. However, this method requires a large hardware overhead, and the synchronous circuit structure is complex, which is easy to cause false triggering and has low reliability. [0003] In the field of frequency measurement, the phase information method is also adopted by many people because it can better track the frequency of dynamic changes and accurately reflect the law of frequency changes. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R23/12
Inventor 王荣华门长有杨昆谭年熊
Owner HANGZHOU VANGO TECH