Real Time PC Implementation of Power Quality Monitoring System Based on Multiharmonic Least-Squares Fitting

To reduce the influence of the static unbalance on an infrared missile guidance system, a new static unbalance measure system for the gimbals axes has been developed. Considering the coupling effects caused by a mass eccentricity, the static balance condition and measure sequence for each gimbal axis are obtained. A novel static unbalance test approach is proposed after analyzing the dynamic model of the measured gimbal axis. This approach is to drive the measured gimbal axis to do sinusoidal reciprocating motion in a small angle and collect its drive currents in real time. Then the static unbalance of the measured gimbal axis can be obtained by the current multi-cycle integration. Also a measuring system using the proposed approach has been developed. A balanced simulator is used to verify the proposed approach by the load and repeatability tests. The results show the proposed approach enhances the efficiency of the static unbalance measurement, and the developed measuring system is able to achieve a high precision with a greater stability.

Section: The Repeatability Testmentioning

confidence: 97%

The Static Unbalance Analysis and Its Measurement System For Gimbals Axes of an Inertial Stabilization Platform

Yang¹,

Zhao²,

Li³

et al. 2015

“…The 2H+1 estimated parameters are   has N rows and 2H+1 columns. The elements of x can be used to estimate the THD using (2) and (3). If the DC component is not required, the algorithm can also be adapted by removing the first element of x and the first column of D without changing the THD estimation results.…”

Section: Non-iterative Multi-harmonic Fittingmentioning

confidence: 99%

“…However, regulatory bodies are usually not concerned with transients, as Quality of Service (QoS) is mainly associated with RMS variations (e.g., sags, swells, interruptions), frequency shifts, flicker, voltage unbalance and harmonic distortion. Therefore, a measurement device used for the assessment of quality of service must measure these parameters in real-time [3] and generate aggregate values according to the regulatory norms in effect in each country [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

On the Use of Multi-Harmonic Least-Squares Fitting for THD Estimation in Power Quality Analysis

Ramos¹,

Janeiro²,

Radil³

2012

Self Cite

The quality of the supplied power by electricity utilities is regulated and of concern to the end user. Power quality disturbances include interruptions, sags, swells, transients and harmonic distortion. The instruments used to measure these disturbances have to satisfy minimum requirements set by international standards. In this paper, an analysis of multi-harmonic least-squares fitting algorithms applied to total harmonic distortion (THD) estimation is presented. The results from the different least-squares algorithms are compared with the results from the discrete Fourier transform (DFT) algorithm. The algorithms are assessed in the different testing states required by the standards.

“…The inter-harmonic component near the fundamental frequency, however, is still difficult to be filtered out. Other algorithms, such as the modified LMS algorithm [23], the least mean phase (LMP) algorithm [24] and the multi-harmonic least-squares fitting algorithm [25] are also reported. Reference [26] presents reviews of the existing several methods, outlining strengths and weaknesses of each one.…”

Section: Introductionmentioning

confidence: 99%

“…In the past several decades, a variety of algorithms [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] for frequency estimation have been reported. Generally, the performance of a frequency estimation algorithm can be evaluated through static and dynamic tests.…”

Section: Introductionmentioning

confidence: 99%

Power System Frequency Estimation Algorithm for Electric Energy Metering of Nonlinear Loads

Zhang¹,

Li²

2012

In this paper, a discrete wavelet transform (DWT) based approach is proposed for power system frequency estimation. Unlike the existing frequency estimators mainly used for power system monitoring and control, the proposed approach is developed for fundamental frequency estimation in the field of energy metering of nonlinear loads. The characteristics of a nonlinear load is that the power signal is heavily distorted, composed of harmonics, inter-harmonics and corrupted by noise. The main idea is to predetermine a series of frequency points, and the mean value of two frequency points nearest to the power system frequency is accepted as the approximate solution. Firstly the input signal is modulated with a series of modulating signals, whose frequencies are those frequency points. Then the modulated signals are decomposed into individual frequency bands using DWT, and differences between the maximum and minimum wavelet coefficients in the lowest frequency band are calculated. Similarities among power system frequency and those frequency points are judged by the differences. Simulation results have proven high immunity to noise, harmonic and inter-harmonic interferences. The proposed method is applicable for real-time power system frequency estimation for electric energy measurement of nonlinear loads.