Real-time Simulation Techniques Research Articles

Artificial neural network-polar coordinated fuzzy controller based maximum power point tracking control under partially shaded conditions

The one of main causes of reducing energy yield of photovoltaic systems is partially shaded conditions. Although the conventional maximum power point tracking (MPPT) control algorithms operate well under uniform insolation, they do not operate well in non-uniform insolation. The non-uniform conditions cause multiple local maximum power points on the power-voltage curve. The conventional MPPT methods cannot distinguish between the global and local peaks. Since the global maximum power point (MPP) may change within a large voltage window and also its position depends on shading patterns, it is very difficult to recognise the global operating point under partially shaded conditions. In this paper, a novel MPPT system is proposed for partially shaded PV array using artificial neural network (ANN) and fuzzy logic with polar information controller. The ANN with three layer feed-forward is trained once for several partially shaded conditions to determine the global MPP voltage. The fuzzy logic with polar information controller uses the global MPP voltage as a reference voltage to generate the required control signal for the power converter. Another objective of this study is to determine the estimated maximum power and energy generation of PV system through the same ANN structure. The effectiveness of the proposed method is demonstrated under the experimental real-time simulation technique based dSPACE real-time interface system for different interconnected PV arrays such as series-parallel, bridge link and total cross tied configurations.

A Comparison of Some Model Order Reduction Methods for Fast Simulation of Soft Tissue Response using the Point Collocation-based Method of Finite Spheres (PCMFS).

In this paper we develop the Point Collocation-based Method of Finite Spheres (PCMFS) to simulate the viscoelastic response of soft biological tissues and evaluate the effectiveness of model order reduction methods such as modal truncation, Hankel optimal model and truncated balanced realization techniques for PCMFS. The PCMFS was developed in [1] as a physics-based technique for real time simulation of surgical procedures. It is a meshfree numerical method in which discretization is performed using a set of nodal points with approximation functions compactly supported on spherical subdomains centered at the nodes. The point collocation method is used as the weighted residual technique where the governing differential equations are directly applied at the nodal points. Since computational speed has a significant role in simulation of surgical procedures, model order reduction methods have been compared for relative gains in efficiency and computational accuracy. Of these methods, truncated balanced realization results in the highest accuracy while modal truncation results in the highest efficiency.

Real-Time Shunt Active Power Filter Compensation

This letter presents the application of a real-time simulation technique to shunt active power filter compensation of the harmonic currents and reactive power in the power system. Available literature details several techniques developed and implemented to perform real-time simulations on the power system analysis. This paper will focus on the following technique: real-time windows target (RTWT) using Matlab/Simulink. Based on the obtained results of the RTWT application, it is possible to obtain simulation conditions that are close to the true real-time environment under study using only a single computer (e.g., the same computer is used as a host and as a target), giving accurate results with relatively low-cost hardware.

Foveated gaze-contingent displays for peripheral LOD management, 3D visualization, and stereo imaging

Advancements in graphics hardware have allowed development of hardware-accelerated imaging displays. This article reviews techniques for real-time simulation of arbitrary visual fields over still images and video. The goal is to provide the vision sciences and perceptual graphics communities techniques for the investigation of fundamental processes of visual perception. Classic gaze-contingent displays used for these purposes are reviewed and for the first time a pixel shader is introduced for display of a high-resolution window over peripherally degraded stimulus. The pixel shader advances current state-of-the-art by allowing real-time processing of still or streamed images, obviating the need for preprocessing or storage.

Real-Time Digital Time-Varying Harmonic Modeling and Simulation Techniques IEEE Task Force on Harmonics Modeling and Simulation

With the growing importance of power quality problems to electric utilities and customers, there is an increased focus on the search for new tools and techniques for accurate analysis and resolution of such problems. This paper reviews currently available techniques for the modeling and simulation of time-varying harmonics in real-time. Following a brief summary of the currently used off-line harmonics modeling and simulation methods, the principles and system element representations using wave digital filter (WDF) and discrete wavelet transform (DWT) methods are discussed. Hardware and software architectures of real-time network simulator (RTNS), HYPERSIM, and PC-cluster based real-time simulator are presented. Towards the end, two case studies are given to demonstrate the real-time analysis of time-varying harmonics generated by a three-phase arc furnace using the PC-cluster based real-time simulator, and a real-time hardware-in-the-loop (HIL) equipment testing using the real-time digital simulator (RTDS)

Real time simulation of nonlinear tissue response in virtual surgery using the point collocation-based method of finite spheres

The point collocation-based method of finite spheres (PCMFS) was introduced as a meshfree technique for real time simulation of surgical processes. While real time graphical rendering requires an update rate of about 30 Hz, a much higher update rate of 1 kHz is necessary for smooth haptic (touch) feedback. The requirement of real time performance is crucial to these simulations and is highly demanding in terms of computational efficiency. In this paper we extend the PCMFS technique to tissue deformations that are geometrically nonlinear. The technique is based on a novel combination of multiresolution approach coupled with a fast reanalysis scheme in which the response predicted by an underlying linear PCMFS model is enhanced in the local neighborhood of the surgical tool-tip by a nonlinear model. We present performance comparisons of PCMFS with traditional finite element models.

A digital control perspective for real-time modeling of electrical switching systems - a case study of linear circuits with diodes

The article describes a digital control technique for real-time modeling and simulation of hybrid systems. The performance of the closed-loop real-time model is close to that of the original continuous-time model. To illustrate the technique, linear circuits equipped with diodes were considered. A voltage source model of the diode is represented as an analog controller in feedback with a linear, time-invariant system and serves as a starting point to a global digital redesign strategy. The objective of digital redesign is to obtain a discrete-time control system that behaves as closely as possible to the LTI continuous-time closed-loop system. The procedure was validated through real-time and off-line simulations of a three-phase diode rectifier.

International cooperation on control for safe operation of nuclear research reactors

The purpose of this paper is to present some of the main reasons, objectives, planning, and recent advances of an SCK·CEN/ININ joint project, which deals with the design and application of modern/expert control and real-time simulation techniques for the safe operation of a TRIGA Mark III research nuclear reactor. This project has been proposed as the first of its kind under a general cooperation agreement between the Belgian Nuclear Research Centre (SCK·CEN) and the National Nuclear Research Institute (ININ) of Mexico.

Modal Warping: Real-Time Simulation of Large Rotational Deformation and Manipulation

This paper proposes a real-time simulation technique for large deformations. Green's nonlinear strain tensor accurately models large deformations; however, time stepping of the resulting nonlinear system can be computationally expensive. Modal analysis based on a linear strain tensor has been shown to be suitable for real-time simulation, but is accurate only for moderately small deformations. In the present work, we identify the rotational component of an infinitesimal deformation and extend traditional linear modal analysis to track that component. We then develop a procedure to integrate the small rotations occurring at the nodal points. An interesting feature of our formulation is that it can implement both position and orientation constraints in a straightforward manner. These constraints can be used to interactively manipulate the shape of a deformable solid by dragging/twisting a set of nodes. Experiments show that the proposed technique runs in real-time, even for a complex model, and that it can simulate large bending and/or twisting deformations with acceptable realism.

Digital simulators expedite relay performance evaluation

This article looks at the various applications of digital simulator technology that have been used to meet the testing requirements of today's more advanced power system protection relays. The authors describe how digital simulators present a new development tool for real-time simulation techniques and for the automation of protective relay testing.

109 人間の知覚特性を考慮した多感覚データ提示

In scientific visualization, it is necessary to take into consideration the characteristic of human perception. A multisensory data sensualization environment was developed in which visual, acoustic, and touch sensation could be used to display scientific data. This paper describes the calibration method of the sense displays based on psychological magnitude and the intuitive data sensualization methods, based on real world metaphor, augmented reality, and real time simulation techniques.

Low-temperature dynamical simulation of spin-boson systems.

The dynamics of spin-boson systems at very low temperatures has been studied using a real-time path-integral simulation technique, which combines a stochastic Monte Carlo sampling over the quantum fluctuations with an exact treatment of the quasiclassical degrees of freedom. To a large degree, this special technique circumvents the dynamical sign problem and allows the dynamics to be studied directly up to long real times in a numerically exact manner. This method has been applied to two important problems: (1) crossover from nonadiabatic to adiabatic behavior in electron-transfer reactions, (2) the zero-temperature dynamics in the antiferromagnetic Kondo region 1/2K1, where K is Kondo's parameter.

Real-Time Simulation of VLF Atmospheric Noise for Use in the Calibration and Characterization of LORAN-C Receivers for Aircraft Navigation

This paper describes a real-time simulation technique for generating realistic VLF band atmospheric noise. Noise in this band consists of a background Gaussian component plus a non-stationary impulsive component. The simulator implements as a real time simulation the theoretical model described in Feldman[1]. Stored channel simulation using a high performance personal computer (PC ) drives an off the shelf multi-channel signal generator, providing a high degree of sophistication at low cost. The simulator developed at the Volpe National Transportation Center has been used to characterize Loran-C receivers for use in aircraft navigation. Examples of use of the new simulator in the characteriza tion of Loran-C receivers are presented.

Applying simulation and expert systems to the control of advanced manufacturing facilities

A decision support environment which combines the concepts of visual interactive simulation and expert systems technologies is described. The resulting system, referred to as a Real Time Interactive Control System (RETICS), has evolved through a feasibility study aimed at applying real-time simulation techniques and expert systems to the control of manufacturing material logistics. Following a description of the principles behind the concept, the discussion considers the various implementation options offered by the system. This begins with an off-line advisory tool, and extends through to a fully integrated subsystem within the overall architecture of an automated manufacturing system.

Personal Computers as a tool for the Analysis, Design and Implementation of Control Systems

The role of IBM / compatible Personal Computers in all the stages of control systems developement and implementation is discussed in the present paper. The real time simulation technique is emphasized due to its advantages in comparison with the traditional simulation techniques and two examples of its application are given. It is concluded that advanced control techniques as identification methods, adaptive controllers, multivariable approaches, etc., can be used and implemented advantageously on the basis of IBM/compatible personal com — puters. Some experiences in this sense are discussed, in particular the main characteristics of the PC digital controllers developed for a multiple-effect evaporator and a paper machine.

A new generation of real-time simulation techniques

This work presents a novel methodology for the development of real-time simulation techniques. They are focused on the PGD method, which allows the solution of complex problems by pre-calculating all the possible results. Subsequently, applications efficiently process these data to show particular results on demand.

A technique for real time simulation of a rigid body problem

A technique for real time simulation of a rigid body problem