Extraction Of Fundamental Component Research Articles

A novel adaptive-fuzzy hysteresis current controller-based active power line conditioners for power quality enhancement

This paper presents a three-phase shunt active power line conditioner (APLC) for harmonics and reactive power compensation to enhance the power quality. The compensation process is based on sinusoidal extraction control method, which consists of positive-sequence voltage detector to regulate the distorted supply voltage and instantaneous real-power for fundamental component extraction from the distorted line current. The voltage source inverter (VSI)-based active filter switching pulses is generated through adaptive fuzzy hysteresis current controller (HCC). For the adaptive-fuzzy-HCC, bandwidth is calculated without precise knowledge of the APLC parameters (interface inductor and DC-link voltage), the hysteresis band value can be implemented with a fuzzy logic. A comparative assessment of fixed-HCC, adaptive-HCC and adaptive-fuzzy-HCC is carried out. The shunt APLC system is validated through extensive simulation under distorted supply voltage and non-linear load conditions.

ANN based Hybrid Active Power Filter for Harmonics Elimination with Distorted Mains

The present paper describes dynamic neural network controlled Hybrid Active Power Filter (HAPF) designed for harmonic compensation under variable source/load conditions. A neural network based controller is employed to extract fundamental component of current from non-sinusoidal and unbalanced source currents of the considered supply system. Hybrid filter utilizing the merits of both shunt passive filter and shunt active filter for better compensation performance is applied in this work. Simulation and analysis of three phase hybrid active power filter under balanced and unbalanced load conditions, unbalanced & distorted source conditions have been incorporated using MATLAB/ SIMULINK. The detailed simulation level results have been presented to validate the proposed methodology. Keywords: Hybrid active power filter, THD, Artificial Neural Network Controller, PI controller. DOI: http://dx.doi.org/10.11591/ijpeds.v2i3.276

Power Components Estimation According to IEEE Standard 1459–2010 Under Wide-Range Frequency Deviations

This paper proposes an accurate and computationally efficient time-domain implementation of the IEEE Standard 1459-2010 for power measurements. The most important parts are adaptive low- and bandpass finite-impulse-response (FIR) filters that extract dc and fundamental components, respectively. In addition, coefficient sensitivity problems of the large-order FIR comb cascade structure are overridden by using a multirate (decimation) digital signal processing technique. Even more, by using decimation antialiasing filters, the parameter estimation accuracy is improved. The symmetrical components are estimated through adaptive transformation matrix of phase shifters. The algorithm convergence provided a fast response and adaptability. The effectiveness of the proposed technique is demonstrated by simulation results. The algorithm shows a very high level of robustness and high measurement accuracy over a wide range of frequency changes.

Microcontroller-Based Numerical Quadrilateral Relay for the Transmission Line Protection

This article presents an Intel 8097 microcontroller-based numerical quadrilateral distance relay for transmission line protection. The numerical filtering algorithm used for the extraction of fundamental frequency components from the corrupted post fault relaying signals is based on Block pulse functions. The microcontroller computes the real and reactive components (R and X) of the apparent impedance of the line as seen by the relay by using the real and imaginary components of the fundamental frequency voltage and current phasors. Using the computed values of R and X, the microcontroller examines whether the fault point lies within the quadrilateral relay's protective zone or not. If the fault point lies in the protective zone of the relay, the microcontroller issues a trip signal to the circuit breaker. The relay is successfully tested for a number of different three step quadrilateral characteristics and the results are obtained. The proposed relay is reliable, flexible, accurate and fast.

DSP Based Neural Network Controlled Parallel Hybrid Active Power Filter

In this paper, a novel neural network controlled Hybrid Parallel Active Power Filter has been presented. The neural network controller comprises two similar adaptive linear neurons (ADALINE), and it has been designed to extract fundamental frequency components from non-sinusoidal and unbalanced currents. It has been shown that the proposed neural controller is simple, fast and accurate. The proposed system is implemented using Digital Signal Processor (DSP). Experimental results with different nonlinear loads are presented to confirm the validity of the proposed technique.

Finding pathogenicity islands and gene transfer events in genome data.

There is a growing literature on wavelet theory and wavelet methods showing improvements on more classical techniques, especially in the contexts of smoothing and extraction of fundamental components of signals. G+C patterns occur at different lengths (scales) and, for this reason, G+C plots are usually difficult to interpret. Current methods for genome analysis choose a window size and compute a chi(2) statistics of the average value for each window with respect to the whole genome. Firstly, wavelets are used to smooth G+C profiles to locate characteristic patterns in genome sequences. The method we use is based on performing a chi(2) statistics on the wavelet coefficients of a profile; thus we do not need to choose a fixed window size, in that the smoothing occurs at a set of different scales. Secondly, a wavelet scalogram is used as a measure for sequence profile comparison; this tool is very general and can be applied to other sequence profiles commonly used in genome analysis. We show applications to the analysis of Deinococcus radiodurans chromosome I, of two strains of Helicobacter pylori (26695, J99) and two of Neisseria meningitidis (serogroup B strain MC58 and serogroup A strain Z2491). We report a list of loci that have different G+C content with respect to the nearby regions; the analysis of N. meningitidis serogroup B shows two new large regions with low G+C content that are putative pathogenicity islands. Software and numerical results (profiles, scalograms, high and low frequency components) for all the genome sequences analyzed are available upon request from the authors.

Microcomputer based digital differential relaying for generator protection: Real time test results

The paper presents the development of a digital differential relaying scheme around a 16-bit microprocessor for generator winding protection. It uses a simple filter algorithm which is based on cross-correlation with a heptagonal wave for the extraction of fundamental frequency components of differential and sum currents. Application of this filter and use of the real parts alone, instead of both the real and imaginary parts, of the fundamental frequency components for the relaying reduces the computation requirement drastically, thus enabling implementation of a complete three-phase differential relay on a single microprocessor without requiring a coprocessor or multiplier. The relay has been tested in real time on simulated generator currents representing internal-, external- and no-fault conditions separately. The test results agree well with the results of off-line evaluation reported earlier and point to a successful implementation of the differential relaying algorithm on a microprocessor in real time.

Application of block pulse functions for digital protection of power transformers

The author describes an application of block pulse functions for digital protection of power transformers. Digital relay algorithms are developed to extract fundamental and second-harmonic components. These components are then used for harmonic restraint differential protection of transformers. In comparison with the algorithms based on the Walsh and Haar functions, the proposed method is computationally simple and can be used with any sampling frequency. It is concluded that offline testing of the method with simulated inrush and internal fault current data clearly indicate that the method can provide fast and reliable trip decision. The method is suitable for microprocessor-based protective relays. >

New algorithms for microprocessor-based distance relaying

System impedance calculation for distance relaying requires extraction of fundamental frequency components from highly distorted post-fault relaying signals. Many algorithms are available for extracting the fundamental frequency component, but most of them involve a large amount of computation, whilst others have low accuracy, or poor convergence, or both. This paper describes two algorithms based on the Hartley transform. They are computationally simple, have good frequency response and give fast convergence in the calculation of resistance and reactance. Their efficacy has been examined using representative voltage and current relaying signals. The results obtained and presented here are gratifying.

Digital protection of transmission lines using block pulse functions

An application of block pulse functions for digital protection of transmission lines is presented. A digital relay algorithm is developed to extract fundamental frequency components. These components are then used to calculate the impedance as seen from the relay location of a transmission line. The method is offline tested using realistic relaying signals of a 230 kV three-phase transmission line, and the results are compared with those of an algorithm based on Haar functions. The proposed algorithm is computationally simple and flexible to use with any sampling frequency.