Real-time determination of power system frequency

Abstract

Abstract-The main frequency is an important parameter of an electrical power system. The frequency can change over a small range due to generation-load mismatches. Some power system protection and control applications, e.g., frequency relay for load shedding, load-frequency controller, require accurate and fast estimation of the frequency. Most digital algorithms for measuring frequency have acceptable accuracy if voltage waveforms are not distorted. However, due to nonlinear devices, e.g., semiconductor rectifiers, electric arc furnaces, the voltage waveforms can include higher harmonics. The paper presents a new method of measurement of power system frequency, based on digital filtering and Prony's estimation method. Simulation results confirm, that the proposed method is more accurate than others, e.g., than the method based on the measurement of angular velocity of the rotating voltage phasor.Index Terms-Discrete Fourier transforms, FIR digital filters, frequency measurement, power system parameter estimation, protective relaying.

An Iterative Least Squares Error Method with Resampling for Frequency Tracking in Power System

“…Suppose the input signal contains a 3 rd order harmonic and a decaying DC offset lasting in several cycles at the beginning of simulation as shown in Equation (8). Parameters used in simulation are listed in At first, we choose the best sampling rate and data window for LSE algorithms, since the performance of these algorithms are highly connected with them.…”

“…In the past several decades researchers have paid much attention to frequency measurement and analysis in power engineering. Types of frequency estimation methods have been reported, such as zero crossing [2,3], demodulation technique [2],Newton algorithm [4], Kalman filter [5~7], prony approach [8], artificial neural network [9], etc. in time-domain.…”

Initial-phase Sensitivity Analysis of Harmonic Measurements via Windowed DFT

“…The Discrete Fourier Transform (DFT) method is widely used in harmonic measurements of industrial power systems [1][2][3], which are steady and dependable, and can be easily implemented in embedded systems. In addition, the DFT based method has been adopted by the IEC61000-4-7 standard [4].…”

Separation and analyzing of harmonics and inter-harmonics based on single channel independent component analysis

“…And artificial neural networks need a large number of training samples. High-resolution parametric techniques such as Prony's method [7] and estimation of signal parameters via rotational invariance technique (ESPRIT) [8,9] provide better accuracy of frequency estimation. However, some other techniques like least squares method are needed in order to estimate the amplitude and phase.…”