Model-based Parameter Estimation Technique Research Articles

Compensating voltage waveform distortions using a practical topology of series active power filters

Addressing harmonics, voltage sags, voltage swells, and asymmetrical variations is essential to seamlessly integrate renewable energy sources, electric vehicle charging stations, and power electronics devices into electric power grids. These issues can significantly impact the sinusoidal symmetry of voltage waveforms. Series Active Power Filters (APFs) present a promising solution that can dramatically improve power quality (PQ) by effectively addressing voltage distortions. This paper first identifies several topology-related impracticalities in the existing literature on series APFs, such as using nonlinear loads or linear loads with a current source. Secondly, to understand the motivations behind these impracticalities, commonly used reference extraction methods, namely, Instantaneous Reactive Power Theory (IRPT) and Synchronous Reference Frame (SRF), are tested on a practical topology consisting of a distorted voltage source and a linear RL load. Results conducted in the MATLAB/Simulink environment show that IRPT fails to extract the reference signal under the practical topology, and SRF leads to unacceptable THDs surpassing the 5% threshold mandated by relevant standards set forth for such applications. Thirdly, the matrix pencil method (MPM), a model-based parameter estimation technique that exploits a voltage waveform's underlying exponential signal model to extract the series APF's reference voltage, is proposed. Extensive simulations showcase the superior performance of the MPM-based series APF. It successfully reduces voltage total harmonic distortion (THD) to below 1.13% across various scenarios, including situations involving harmonic-polluted voltage sources, incorporating nonlinear loads, sag and swell phenomenon, and capacitor utilization in DC link implementation.

A Filter-Less Time-Domain Method for Reference Signal Extraction in Shunt Active Power Filters

Current distortion degrades power quality and affects system performance, especially for sensitive loads that require pure sinusoidal waves. Owing to its excellent dynamic response, a well-designed active power filter (APF) can achieve a total harmonic distortion (THD) within the acceptable limits defined by IEEE 3002 standards through compensating harmonic distortions. The APF consists of two main modules: a reference signal extraction module and a modulation module. This paper adapts the matrix pencil method, a well-known model-based parameter estimation technique, to the problem of reference extraction. Contrary to conventional time-domain methods such as the synchronous reference frame (SRF) and the reactive power theory (PQ theory) that rely on low-pass filters in their implementations, the proposed method does not use a filter. However, it extracts the reference signal by first decomposing the load current into its constituent frequency components, and then subtracting the pure sine wave synthesized from the obtained fundamental component from the load current. Results on simulated data from MATLAB/Simulink confirm the higher accuracy and fast response time of the proposed method in extracting the reference signal.

Parameter estimation of a six-lump kinetic model of an industrial fluid catalytic cracking unit

In this work a simulation of detailed steady state model of an industrial fluid catalytic cracking (FCC) unit with a newly proposed six-lumped kinetic model which cracks gas oil into diesel, gasoline, liquefied petroleum gas (LPG), dry gas and coke. Frequency factors, activation energies and heats of reaction for the catalytic cracking kinetics and a number of model parameters were estimated using a model based parameter estimation technique along with data from an industrial FCC unit in Sudan. The estimated parameters were used to predict the major riser fractions; diesel as 0.1842 kg-lump/kg-feed with a 0.81% error while gasoline as 0.4863 kg-lump/kg-feed with a 2.71% error compared with the plant data. Thus, with good confidence, the developed kinetic model is able to simulate any type of FCC riser with six-lump model as catalyst-to-oil (C/O) ratios were varied and the results predicted the typical riser profiles.

Rotor fault diagnosis in induction motors by the matrix pencil method and support vector machine

This paper proposes a high-resolution motor-current-signature-analysis method and a supervised learning algorithm for the detection and classification of broken rotor bars and broken end-ring connectors in 3-phase induction motors. Signature analysis relies on the matrix pencil method (MPM), a well-known model-based parameter estimation technique, to extract representative features or signatures from stator current signals. Extracted feature vectors are subsequently used to train off-line a support vector machine classifier. Once trained, the classifier is tested on a benchmark dataset of simulated stator current signals representing healthy and faulty rotors with the aim of classifying the underlying motor condition. The obtained results validate the matrix pencil method as a feature extraction method and show that the trained classifier achieves a 100% success rate in identifying the number of broken bars and connectors. Moreover, the advantages of the matrix pencil method over fast Fourier transform are demonstrated using experimental data.

Fast Wideband Solutions Obtained Using Model Based Parameter Estimation with Method of Moments

Integration of the Model Based Parameter Estimation (MBPE) technique into Method of Moments (MOM) provides fast solutions over a wide frequency band to solve radiation and scattering problems. The MBPE technique uses the Padé rational function to approximate solutions over a wide frequency band from a solution at a fixed frequency. In this paper, the MBPE technique with MOM is applied to a thin-wire antenna. The solutions obtained by repeated simulations of MOM agree very well with the solutions obtained by MBPE technique in a single simulation. Therefore, MBPE technique according to MOM provides a remarkable saving in the computation time. Computed results show that solutions at a wider frequency band of interest are achieved in a single simulation.

Accelerating the frequency-domain response calculation of complex grounding system using wavelet based MBPE technique

The transient response of grounding systems is essential for their designs and related electromagnetic compatibility problems in power systems. Although the method of moments (MoM) is a popular way to analyze the responses of grounding systems, it is prohibitively slow. In this paper, the model-based parameter estimation (MBPE) technique and wavelet matrix transform (WMT) are combined and applied to the method of moments (MOM). It is expanded on two-steps technique to accelerate solution of electric field integral equations (EFIE). In a first step, the WMT is used to get a sparse matrix equation in wavelet-domain. Then in a second step, the adaptive model-based parameter estimation is used to reduce the number of frequency-domain calculation points required for the evaluation of space–time current distribution along a grounding grid. The accuracy of the proposed model is confirmed by comparing the simulation results of several case studies with those obtained using the direct MoM method combined with inverse fast Fourier transform (IFFT). It is shown that considerable computation efficiency is achieved in terms of CPU time without losing accuracy.

Application of AIM and MBPE Techniques to Accelerate Modeling of 3-D Doubly Periodic Structures with Nonorthogonal Lattices Composed of Bianisotropic Media

An efficient methodology is introduced for rapid analysis and design of three-dimensional (3-D) doubly periodic structures over a wide frequency range based on hybrid finite element boundary integral (FEBI) methods. The 3-D doubly periodic structures can be represented as nonorthogonal lattices composed of general inhomogeneous bianisotropic media with arbitrarily-shaped metallic patches. Based on Floquet theory and periodic boundary conditions, the original stated problem that involves infinite periodic structures can be converted into a single unit cell. Using the equivalence principle, the derived BI equation formulation is applied to the top and bottom surfaces of the unit cell, which results in a perfectly reflectionless boundary condition for the FE-based approach. Then, the unit cell was meshed using triangular prismatic volume elements, which provide a great deal of flexibility in modeling complex planar geometries with arbitrary shapes in the transverse direction. The adaptive integral method (AIM) was employed to accelerate the calculation of the matrix-vector product for the BI portion within the iterative solver. Furthermore, a model-based parameter estimation (MBPE) technique was proposed for the wide-band interpolation of the required impedance matrix elements in the BI part for near field components that were used in the AIM procedure. The accuracy and efficiency of the proposed hybrid algorithms are demonstrated by the presented numerical results (e.g., in comparison with analytical solutions). Several simulation results are presented to illustrate the flexibility of the proposed methods for analysis of frequency selective surfaces with arbitrarily-shaped metallic patches, bianisotropic materials, and nonorthogonal lattice configurations.

Wavelet Based MBPE Technique for Fast RCS Computation of DNG Metamaterials

Described by the drude model, the DNG metamaterials is essentially a dispersive media, the scattering analysis of it over broad band by asymptotic waveform evaluation (AWE) technique is difficult since the computation of high order differential coefficients for the impedance matrix elements, to reduce the differential order, the model-based parameter estimation (MBPE) technique based on two expanded points is applied to analysis the scattering characters of double-negative (DNG) metamaterials. A wavelet matrix transform (WMT) is used to get a sparse matrix equation in wavelet-domain, which is solved over a broad frequency band by the MBPE. As compared with AWE, the MBPE technique obtained more accurate results over a broader frequency band.

Using MBPE technique to accelerate solving the thin-wire EFIE used in numerical simulation of lightning

The antenna theory (AT) model is widely used to numerically simulate the propagation of current wave along lightning return-stroke channels and compute the radiated electromagnetic fields. In this model, the return stroke channel is considered as a vertical monopole antenna above perfectly conducting ground for which the numerical solution of the governing electric field integral equation (EFIE) in the frequency domain by the conventional method of moment (MoM) is prohibitively slow. In this paper, a model-based parameter estimation (MBPE) technique is proposed to reduce the number of frequency-domain calculation points required for the evaluation of space-time current distribution along a lightning return stroke channel. In applying this technique to a rational function model for the channel current distribution, a uniform-like sampling strategy is investigated. In order to accelerate the building of the moment impedance matrix, the reciprocal closed-form mutual impedance of sinusoidal electric dipoles and the symmetry of the model are used. The proposed technique is validated against the conventional inverse fast Fourier transform algorithm which uses a MoM solution for all frequencies within the channel base current spectrum. It is shown that considerable computation efficiency is achieved in terms of CPU time without losing accuracy.

Metallic and dielectric photonic crystal filter design using multiple multipole program and model-based parameter estimation methods

Ultra compact photonic crystal filters with and without metallic parts operating at telecommunication wavelengths are designed using the multiple multipole program combined with the model-based parameter estimation technique. Material loss is taken into account and measured material properties are employed for practical design considerations. Stochastic and deterministic optimization techniques are applied to obtain optimum filter characteristics.

Design of ultra-compact metallo-dielectric photonic crystal filters

Filter characteristics of metallo-dielectric photonic crystal slabs are analyzed using the Multiple Multipole Program combined with the Model-Based Parameter Estimation technique. This approach takes losses and material dispersion into account and provides highly accurate results at short computation time. Starting from this analysis, different ultra-compact band pass filters for telecommunication wavelengths are designed. The filters consist of five silver wires embedded in a waveguide structure. By applying stochastic and deterministic techniques the filter structures are optimized to obtain the desired characteristics.

Generalized System Function Analysis of Exterior and Interior Resonances of Antenna and Scattering Problems

The generalized system function H(s), directly associated with radiated and scattered fields, is presented to effectively analyze the exterior and interior resonances of antenna and scattering systems in this paper. H(s) is constructed by using the model-based parameter estimation technique combined with the complex frequency theory. The behaviors of the exterior and interior resonances can be distinguished by analyzing the characteristics of pole-zero of H(s) in a finite operational frequency band. The intensity of the exterior resonance can be effectively estimated in terms of Q values and residues at the complex resonant frequencies. The truly scattered fields from a closed conducting region can be obtained by eliminating the poles corresponding to the interior resonances from H(s). Some examples of the practical antenna arrays and scattering systems are given to illustrate the application and validity of the proposed approach in this paper.

Self-tuning and Self-adaptive Control of a Heating Process by Distributed Microprocessors

This paper investigates and evaluates two different control approaches, namely: (i) Self-adaptive discrete control and identification techniques based on Z-transformation, and (ii) Self-tuning continuous control and parameter estimation techniques, both implemented by microprocessor based distributed control system, The process is a heating equipment designed to deliver the heated medium (water) at a specified temperature from a tank under load (flow) variations. The heating of the water is done in an enclosure before entering the tank whose temperature is controlled. Flow fluctuations through the tank and level fluctuations within the tank are imposed and the algorithms are evaluated for comparison. Recursive least square methodology with a variable “forgetting factor” is used for identification. Model-based parameter estimation techniques and measurements are utilized to design the self-tuning controls based on continuous system approaches. A self-tuned Smith predictor along with a self-tuning PID control were used. The effect of sampling time in both algorithms is discussed. The chosen implementation is with a distributed microprocessor system. The system used has both discrete, and continuous algorithm forms available as configurable “function blocks” (functional programming).

KIRON: A computer system and a methodology applicable to the study of erythroid disorders

A methodology for the study of erythroid disorders by means of mathematical models and classification techniques is proposed, and KIRON, a comprehensive computer system for patient data entry, management, and analysis is described. KIRON is used in a hematologic laboratory for accurate collection of patient data and for conversational access to the data for processing with model-based parameter estimation techniques, statistical descriptive, multivariate, and pattern-recognition techniques. The user-interface software is designed for convenience of a noncomputer-expert user throughout the whole range of functions performed by the system. System application (a) in the data collection routine, (b) for improving the diagnostic process in clinical routine, (c) for developing a data bank oriented to the study of erythroid disorders, and (d) for analyzing the data bank through the exploratory research strategy are discussed. The system software is entirely written in Fortran and operates under the time-sharing system of a Honeywell 6040 computer.