OSCILLATION-BASED TESTING METHOD FOR DETECTING SWITCH FAULTS IN HIGH-Q SC BIQUAD FILTERS

Testing switched capacitor circuits is a challenge due to the diversity of the possible faults. A special problem encountered is the synthesis of the test signal that will control and will make the fault-effect observable at the test point. The oscillation based method which was adopted for testing in these proceedings resolves that important issue by his nature. Here we discuss the properties of the method and the conditions to be fulfilled in order to implement it in the right way. To achieve that we resolved the problem of synthesis of the positive feed-back circuit and the choice of a proper model of the operational amplifier. In that way a realistic foundation to the testing process was generated. A second order notch cell was chosen as a case-study. Fault dictionaries were developed related to the catastrophic faults of the switches used within the cell. The results reported here are a continuation of our previous work and are complimentary to some other already published

A NON-INTRUSIVE IDENTIFICATION OF HOME APPLIANCES USING ACTIVE POWER AND HARMONIC CURRENT

In recent years, research on non-intrusive load monitoring has become very popular since it allows customers to better manage their energy use and reduce electrical consumption. The traditional non-intrusive load monitoring method, which uses active and reactive power as signatures, has poor performance in detecting small non-linear loads. This drawback has become more prominent because the use of nonlinear appliances has increased continuously during the last decades. To address this problem, we propose a NILM method that utilizes harmonic current in combination with the changes of real power. The advantages of the proposed method with respect to the existing frequency analysis based NILM methods are lower computational complexity and the use of only one feature to characterize the harmonic content of the current

QRS COMPLEX DETECTION BASED ECG SIGNAL ARTEFACT DISCRIMINATION

Recent development in the area of wireless communications enabled advances in healthcare technology. Now, medical personnel are able to simultaneously observe electrocardiogram signals of large number of remote patients. The electrocardiogram signals are acquired by the patients themselves at their homes or other places far away from hospitals, and are transmitted almost instantly through modern communication systems. Unfortunately, the quality of the acquired signals is highly susceptible to artefacts. Here we outline a new algorithm dedicated to electrocardiograph telemetry systems which evaluates the quality of signals measured in unsupervised environments, rises the certainty of the produced diagnoses, and accelerates protective actions when necessary

Computer workstation vetting by supply current monitoring

It is our goal within this project to develop a powerful electronic system capable to claim, with high certainty, that a malicious software is running (or not) along with the workstations’ normal activity. The new product will be based on measurement of the supply current taken by a workstation from the grid. Unique technique is proposed within these proceedings that analyses the supply current to produce information about the state of the workstation and to generate information of the presence of malicious software running along with the rightful applications. The testing is based on comparison of the behavior of a fault-free workstation (established i advance) and the behavior of the potentially faulty device

DESIGN OF IIR DIGITAL FILTERS WITH CRITICAL MONOTONIC PASSBAND AMPLITUDE CHARACTERISTIC - A CASE STUDY

A case study is reported related to the design of IIR digital filters exhibiting critical monotonic amplitude characteristic (CMAC) in the pass band. This kind of amplitude characteristic offers several advantages as compared to its non-monotonic counterparts while it is not studied thoroughly, if at all. After giving a short overview of the way of generation CMACs, arguments will be listed in favor of the IIR version of the digital filter function realization. Next, the IIR implementation of the digital filters will be shortly considered. The main part of the paper will be devoted to the design sequence of this kind of filters which will be illustrated on the example of a band-pass filter obtained by a set of transformations from an all-pole low-pass analogue prototype. This will be for the first time a CMAC band pass IIR digital filters to be reported

IMPLEMENTATION OF ARTIFICIAL NEURAL NETWORKS BASED AI CONCEPTS TO THE SMART GRID

 ICT and energy are two economic domains that became among the most influential to the growth of modern society. These, in the same time, due to exploitation of natural resources and producing unwanted effects to the environment, represent a kind of menace to the eco system and the human future. Implementation of measures to mitigate these unwanted effects established a new paradigm of production and distribution of electrical energy named smart grid. It relies on many novelties that improve the production, distribution and consumption of electricity among which one of the most important is the ICT. Among the ICT concepts implemented in modern smart grid one recognizes the artificial intelligence and, specifically the artificial neural network. Here, after reviewing the subject and setting the case, we are reporting some of our newest results aiming at broadening the set of tools being offered by ICT to the smart grid. We will describe our result in prediction of electricity demand and characterization of new threats to the security of the ICT that may use the grid as a carrier of the attack. We will use artificial neural networks (ANNs) as a tool in both subjects

CHARACTERIZATION OF NONLINEAR LOADS IN POWER DISTRIBUTION GRID

Electronic devices are complex circuits, consisting of analog, switching, and digital subsystems that require direct current (DC) for polarization. Since they are connected to the mains delivering alternating current (AC), however, AC-to-DC converters are to be introduced between the mains and the electronics to be fed. A converter is an electric circuit containing several subsystems, the most important being the switch-mode power supply, drawing power from the mains in pulses hence it is highly nonlinear. That happens, in reduced amplitude, even when the electronics to be fed is switched off. The process of AC-to-DC conversion is not restricted to feeding electronic equipment only. It is more and more frequently encountered in modern smart-grid facilities giving rise to the importance of the studies referred hereafter. The converter can be studied (theoretically or by measurements) as two-port network with reactive and nonlinear port-impedances. Characterization is performed after determining the port electrical quantities which are voltages and currents. Based on these data power and power quality parameters – power factor and total harmonic distortion- may be extracted. When nonlinear loads are present, one should introduce new ways of thinking into the considerations due to the existence of harmonics and related power components. In that way the power factor can be generalized to total or true power factor where the apparent power, involved in its calculations, includes all harmonic components. After introducing a wide range of definitions used in contemporary literature, here we describe our measurement set-up both as hardware and a software solution. The results reported unequivocally confirm the importance of the subject of characterization of small nonlinear loads to the grid having in mind their number which is rising without saturation seen in the near and even far future