Power Line Disturbances Research Articles

Signal quality evaluation of single-channel respiratory sEMG recordings

This work presents a learning-based approach to respiratory surface electromyography (sEMG) quality evaluation. For this purpose, we define the signal-to-disturbance ratio (SDR), which quantifies the relative impact of disturbances on affected signal components. The SDR values for different disturbance types are estimated based on signal and disturbance characteristics and serve as a measure of signal quality. For the multivariate regression task, a fully connected neural network with three layers is trained based on standard and handcrafted signal features. The features are extracted before and after removing cardiac artifacts. This integration of domain-specific knowledge enables us to leverage shallow neural networks, which contributes to the interpretability of the method. For training and testing, artificially disturbed signals are generated based on undisturbed clinical sEMG recordings of mechanically ventilated patients and different disturbance models. This includes single and combined disturbances with different SDRs. The results show that the root-mean-square error (RMSE) of the estimated to the applied SDR regarding powerline (2.3dB) and spike-like disturbances (2.1dB) is smaller than the RMSE referring to high-frequency disturbances (3.6dB) and motion artifacts (5.8dB). Our findings also indicate that the SDR is estimated similarly well regardless of whether one or more contaminants are present simultaneously. Overall, the SDR can be determined with an RMSE of 3.8dB and a correlation coefficient of 0.97. This work contributes to automatically quantifying the impact of disturbances and objectively assessing the quality of sEMG signals of the respiratory muscles.

The Influence of Filters on EEG-ERP Testing: Analysis of Motor Cortex in Healthy Subjects.

The raw EEG signal is always contaminated with many different artifacts, such as muscle movements (electromyographic artifacts), eye blinking (electrooculographic artifacts) or power line disturbances. All artifacts must be removed for correct data interpretation. However, various noise reduction methods significantly influence the final shape of the EEG signal and thus its characteristic values, latency and amplitude. There are several types of filters to eliminate noise early in the processing of EEG data. However, there is no gold standard for their use. This article aims to verify and compare the influence of four various filters (FIR, IIR, FFT, NOTCH) on the latency and amplitude of the EEG signal. By presenting a comparison of selected filters, the authors intend to raise awareness among researchers as regards the effects of known filters on latency and amplitude in a selected area—the sensorimotor area.

Modified Variational Mode Decomposition for Power Line Interference Removal in ECG Signals

Power line interferences (PLI) occurring at 50/60 Hz can corrupt the biomedical recordings like ECG signals and which leads to an improper diagnosis of disease conditions. Proper interference cancellation techniques are therefore required for the removal of these power line disturbances from biomedical recordings. The non-linear time varying characteristics of biomedical signals make the<strong> </strong>interference removal a difficult task without compromising the actual signal characteristics. In this paper, a modified variational mode decomposition based approach is proposed for PLI removal from the ECG signals. In this approach, the central frequency of an intrinsic mode function is fixed corresponding to the normalized power line disturbance frequency. The experimental results show that the PLI interference is exactly captured both in magnitude and phase and are removed. The proposed approach is experimented with ECG signal records from MIT-BIH Arrhythmia database and compared with traditional notch filtering.

Modified Variational Mode Decomposition for Power Line Interference Removal in ECG Signals

Power line interferences (PLI) occurring at 50/60 Hz can corrupt the biomedical recordings like ECG signals and which leads to an improper diagnosis of disease conditions. Proper interference cancellation techniques are therefore required for the removal of these power line disturbances from biomedical recordings. The non-linear time varying characteristics of biomedical signals make the<strong> </strong>interference removal a difficult task without compromising the actual signal characteristics. In this paper, a modified variational mode decomposition based approach is proposed for PLI removal from the ECG signals. In this approach, the central frequency of an intrinsic mode function is fixed corresponding to the normalized power line disturbance frequency. The experimental results show that the PLI interference is exactly captured both in magnitude and phase and are removed. The proposed approach is experimented with ECG signal records from MIT-BIH Arrhythmia database and compared with traditional notch filtering.

다중레이트 디지털 필터 설계 및 심전도 신호의 기저선 변동 및 전원 잡음 제거

Baseline drift reduction and removal of power line noises in electrocardiogram are often necessary to avoid the distortions in extracting the fiducial features. With this aim, the multirate digital filtering algorithm is suggested to design and implement Finite Impulse Response or Infinite Impulse Response Filter by changing the sampling rate with omitting or interpolating intermediate ECG data. After the experimental simulations performed, we can conclude the fact that we can suppress the baseline wander and power line disturbances in ECG signal with reducing the computational complexities in which we do not keep the original and high sampling frequency.

독립성분 분석기법에 의한 심전도 신호의 왜곡 보정

In this study, Independent Component Analysis (ICA) algorithms are suggested to extract the original ECG part from the mixed signal contaminated with the unwanted frequency components and especially 60㎐ power line disturbances. With this aim, we implement a novel method to suppress the baseline-wandering disturbances and power line artefacts contained in patch-electrodes sensory ECG data by separating the unmixed signal with finding the optimal weight W based on Kurtosis value. With applying brutal force and gradient ascent searching algorithm to find W, we can conclude that the unwanted frequency components especially in the ambulatory ECG data can be eliminated by Independent Component Analysis.

Elimination of noise on transcranial Doppler signal using IIR filters designed with artificial bee colony – ABC-algorithm

Biomedical signals are usually contaminated by noise generated from sources such as power line interference and disturbances produced by the movement of the recording electrodes. Also the signal-to-noise ratio of biomedical signals is usually quite low. In addition, biomedical signals often interfere with each other. Therefore, the filters employed for eliminating noise and interference are significant in the medical practice. Digital infinite impulse response (IIR) filters have shorter filter length than the finite impulse response (FIR) filters with the same frequency characteristic. Therefore, in this work, an approach based on digital IIR filters are described for the elimination of noise on transcranial Doppler by using artificial bee colony (ABC) which is a popular swarm based optimization algorithm introduced recently. Moreover, the performance of the proposed approach is compared to particle swarm optimization algorithm.

The Central Italy Electromagnetic Network and the 2009 L'Aquila Earthquake: Observed Electric Activity

A network of low frequency electromagnetic detectors has been operating in Central Italy for more than three years, consisting of identical instruments that continuously record the electrical components of the electromagnetic field, ranging from a few Hz to tens of kHz. These signals are analyzed in real time and their power spectrum contents and time/frequency data are available online. To date, specific interest has been devoted to searching for any possible electromagnetic features which correlate with seismic activity in the same region. In this study, spectral analysis has evidenced very distinct power spectrum signatures that increased in intensity when strong seismic activity occurred near the stations of the 2009 L'Aquila earthquake. These signatures have revealed horizontally oriented electric fields, between 20 Hz to 400 Hz, lasting from several minutes to up to two hours. Their power intensities have been found to be about 1 μV/m. Moreover, a large number of man-made signals and meteorologic electric perturbations were recorded. Anthropogenic signatures have come from power line disturbances at 50 Hz and higher harmonics up to several kHz, while radio transmissions have influenced the higher kHz spectrum. Reception from low frequency transmitters is also provided in relation to seismic activity. Meteorologic signatures cover the lower frequency band through phenomena such as spherics, Schumann resonances and rain electrical perturbations. All of these phenomena are useful teaching tools for introducing students to this invisible electromagnetic world.

A common‐mode replica compensated inductor–capacitor voltage‐controlled oscillator for mixed‐signal system‐on‐chip applications

SUMMARYA novel 1.57 GHz complementary metal–oxide semiconductor inductor–capacitor voltage‐controlled oscillator with the common‐mode replica compensation is introduced for mixed‐signal system‐on‐chip applications. In order to alleviate power line disturbances, the center tap node of differential symmetric inductor and the replica biasing circuit are adopted in the differential voltage regulating unit to reduce power supply sensitivity. In addition, this proposed design also leads to low tuning gain and low power dissipation. The post‐layout simulation results under the Taiwan Semiconductor Manufacturing Company's mixed‐signal 0.18 µm 1P6M process show that the proposed design achieves power supply rejection of −68.6 dB at low frequencies and 1.2 MHz/V pushing sensitivity. It exhibits phase noise of −130.6 dBc/Hz at a 1 MHz offset from a 1.57 GHz carrier yet dissipates only 5.58 mW under a 1.8 V power supply. Copyright © 2011 John Wiley & Sons, Ltd.

Development of elements of biomedical systems based on ultrasensitive biomagnetometry

Some improvements of biomagnetic apparatus and measuring procedures have been made such as 2-channel SQUID-magnetometer with changeable base, optimization of antenna, and minimization of power-line disturbances. The future of developed approaches for increasing noise-immunity of devices at unshielded environment have been demonstrated. Experiments in scheme of passive and active location for studying magnetic nanoparticles injected into lab animals have been provided.

A low-noise multi-channel device for the monitoring of systemic electrical signal propagation in plants

Long-distance electrical signals generated in locally stimulated plants are linked with systemic physiological responses. The propagation of electrical signal through a plant can be measured by multiple electrodes attached to different sites of a plant body. As this signal has to be measured with the sensitivity of tens of microvolts, it can be easily disturbed by power-line hums or external electromagnetic fields. These disturbances can mimic the action potentials generated by a plant. In this work, we present a brief summary of various experimental approaches to the measurement of surface electrical potential (SEP) on a plant and a description of our multi-channel device for the SEP measurement. The main advantages of our measuring system are galvanic separation of the measuring unit, resulting in the elimination of power-line disturbances, and simple and stable contact of Ag/AgCl-peletted electrodes with the plant surface, facilitated by an ordinary gel used in human electrocardiography. These improvements enabled us to detect unperturbed variation (slow) and action (fast) potentials on a plant, as demonstrated by the four-electrode measurement of the electrical signal propagation in a locally wounded tomato plant.

Tremor suppression in ECG.

BackgroundElectrocardiogram recordings are very often contaminated by high-frequency noise usually power-line interference and EMG disturbances (tremor). Specific method for interference cancellation without affecting the proper ECG components, called subtraction procedure, was developed some two decades ago. Filtering out the tremor remains a priori partially successful since it has a relatively wide spectrum, which overlaps the useful ECG frequency band.MethodThe proposed method for tremor suppression implements the following three procedures. Contaminated ECG signals are subjected to moving averaging (comb filter with linear phase characteristic) with first zero set at 50 Hz to suppress tremor and PL interference simultaneously. The reduced peaks of QRS complexes and other relatively high and steep ECG waves are then restored by an introduced by us procedure called linearly-angular, so that the useful high frequency components are preserved in the range specified by the embedded in the ECG instrument filter, usually up to 125 Hz. Finally, a Savitzky-Golay smoothing filter is applied for supplementary tremor suppression outside the QRS complexes.ResultsThe results obtained show a low level of the residual EMG disturbances together with negligible distortion of the wave shapes regardless of rhythm and morphology changes.

POWER QUALITY DISTURBANCE MAGNITUDE CHARACTERIZATION USING WAVELET TRANSFORMATION ANALYSIS PART 2 – APPLICATION

Power quality disturbances (PQD) are normally monitored by dedicated power quality devices. The devices capture disturbances waveform in real-time. Magnitude is accepted as a significant index for detection, general classification and later assessment analysis. To choose suitable way of magnitude characterization is a fundamental work of PQD measuring and monitoring. This study presents three different ways, RMS voltage, peak voltage and fundamental voltage component, to determine magnitude. The algorithms of the three approaches implemented are wavelet transformation (WT) based. In this paper, several approaches to detect, localize, and investigate the feasibility of classifying various types of PQD are presented. The approaches are based on wavelet transform analysis, particularly the Paul, Gaussian and Daubechies wavelet transform. The key idea underlying the approaches is to decompose a given disturbance signal into time-frequency phase, which represent a smoothed version and a detailed version of the original signal. The decomposition is performed using signal decomposition techniques. The proposed technique to detect and localize disturbances with actual power line disturbances is demonstrated and tested. To enhance the detection outcomes, the squared wavelet transform coefficients of the analyzed power line signal are utilized. Based on the results of the detection and localization, an initial investigation of the ability to uniquely characterize various types of PQD is carried on. This investigation is based on characterizing the uniqueness of the squared wavelet transform coefficients for each PQD.

POWER QUALITY DISTURBANCE MAGNITUDE CHARACTERIZATION USING WAVELET TRANSFORMATION ANALYSIS PART 1 – THEORY

In this paper, a few approaches to detect, localize, and investigate the feasibility of classifying various types of power quality disturbances are presented. The approaches are based on wavelet transform analysis, particularly the Paul, Gaussian, and Daubechies wavelet transform. The key idea underlying the approaches are to decompose a given disturbance signal into other signals which represents transforming a one-dimensional time series into two-dimensional time–frequency space. The decomposition is performed using the Paul, Gaussian, and Daubechies wavelet transform techniques. The techniques to detect and localize disturbances with actual power line disturbances are proposed, and then demonstrated and tested. In order to enhance the detection outcomes, the squared wavelet transform coefficients of the analyzed power line signal are utilized. Based on the results of the detection and localization, an initial investigation of the ability to uniquely characterize various types of power quality disturbances is carried out. This investigation is based on characterizing the uniqueness of the squared wavelet transform coefficients for each power quality disturbance.

Some results of investigations on the space weather influence on functioning of several engineering–technical and communication systems and human health

Some results of a complex study on the influence of such space weather factors as the effects of scintillation, solar and geomagnetic storms on human health and some engineering–technical systems both space borne and of ground-based origin are briefly described. The morphology and main characteristics of ionospheric scintillation, together with its impacts on navigation and communication systems, are developed to help space system designers who are involved in activities related to the development of systems in middle latitudes for microwave radio signals for the satellite-receiver path. A study of the effects of geomagnetic storms on electrical power generation and transmission network and equipment, that is the influence of the geomagnetically induced currents of selected magnetic storms and relevant power cuts has revealed that power line disturbances mainly occur when the geomagnetic field displays sharp changes. For the purposes of studying the possible influence of the solar and geomagnetic activity...

Power Quality Solutions to Mitigate the Impact of Voltage Sags in Manufacturing Facilities

ABSTRACT The dominant power quality problems in industrial manufacturing applications are short duration voltage sags and momentary interruptions. For ‘normal’ grid customers, the EPRI Distribution Power Quality study clearly demonstrated that the vast majority of power line disturbances are of short duration. For customers connected to ‘premium’ grids, realized with dual independent distribution feeds with high-speed make-before-break ATS systems, connection to transmission grids, or use of highly meshed grids, short duration voltage sags represent essentially 100 percent of the power disturbances they experience. Power quality solutions, which protect against all short duration power line disturbances, provide protection against virtually 100 percent of all the events experienced by those customers who have the highest cost of downtime, the ‘premium’ grid customers. With the increasing demands for minimizing downtime in manufacturing operations, facilities managers have been challenged to identify cost-effective solutions to address power quality related problems. This article will provide an overview of the power protection issues faced by industrial facilities, based on a review of utility PQ problems, typical plant power distribution systems, and sensitivity of various equipment and processes. Select applications' experience of power electronics-based PQ solutions, such as the Dynamic Sag Corrector® (DySC®—pronounced ‘disk’), in critical manufacturing operations will be presented. The selection criteria will be highlighted to demonstrate how the solution configuration, rating and placement within a facility impacts its economic viability. The pros and cons of ‘facility wide’ versus ‘point of use protection’ will be discussed. Finally, the issues related to ROI for manufacturing processes will be discussed.

Interference characterisation of a commercial Joule–Thomson cooler to be used in a SQUID-based foetal heart monitor

At the University of Twente, a foetal heart monitor based on a high- T C SQUID magnetometer system is under development. The purpose of this system is to measure a foetal heart signal in a clinical environment. For cooling a first demonstrator version, a closed-cycle Joule–Thomson cooler from APD Cryogenics – the Cryotiger ® – was selected. In this work, the Cryotiger is characterised with respect to three noise generating mechanisms: electromagnetic interference, mechanical vibrations and temperature fluctuations. The electromagnetic interference of the cold tip was below the resolution of our 3-axis fluxgate magnetometer ( 7 pT/ Hz ). The interference from the compressor, however, requires it to be placed 2 m or more from the sensor head in order to remain below the environmental power line disturbances. As mechanical vibrations of a magnetometer in a background field – the earth magnetic field – will result in an apparent field at the frequency of vibration, we require the rotation of the cold tip to remain below 200 μrad in the frequency band of interest (0.5–100 Hz). This was checked by applying a magnetic field to a SQUID magnetometer mounted on the cooler's cold tip. In this way, rotations of 3 μrad and translations of 40 nm of the Cryotiger were measured; both at a frequency of 49 Hz. A further issue with respect to our application is the fluctuation in operating temperature. Under no-load operation, the temperature occasionally increased from around 70 K to about 82 K. With a load of roughly 2 W, a temperature of about 74 K was obtained, which increased about 2 K over a 20 day period.

Voltage regulator for contactor ridethrough

This paper describes a simple voltage regulator that allows contactors to ride through power line disturbances such as sags and dropouts. The voltage regulator protects critical equipment in continuous process industries and prevents loss caused by downtime. The voltage regulator is inexpensive and easily retrofitted into existing installations. A field trial of the voltage regulator has been successfully completed.

Analysis of Rectifier Failure to Power Line Transients

The current trend of electronic industry is towards the manufacture of high power factor equipments. which increases the power quality of a.c. utility. These equipments have to be connected directly to a.c. utility, hence they should be immune to power line disturbances. especially the transient disturbances. The high-energy transients can cause component destruction or overheating and deterioration. Front-end rectifiers may be completely destroyed by such transients during their normal working. This paper presents one such voltage transient, which destroys a diode in the front-end rectifier and gives a procedure to select protective component to prevent such destruction that can be adopted in common designs. A curve for selecting the protective component against such transients is also presented.

A virtual digital signal-processing instrument for measuring superimposed power line disturbances

A virtual digital signal-processing instrument capable of automatically extracting and measuring disturbances superimposed on power line voltages in electrical power systems is presented here. A suitable high performance data-acquisition card is mandated to acquire and digitise the input line signal. Digital processing tasks are carried out by exploiting the properties of the wavelet transform. In particular, the continuous wavelet transform and the discrete time wavelet transform are combined in order to set up a reliable measurement method. The user interface is developed in a common iconic programming language. After some theoretical remarks about the wavelet transform and the proposed measurement method, hardware and software solutions adopted for setting up the instrument are presented. The results of the performance verification of the instrument along with those obtained from the analysis of actual superimposed power line disturbances are also given.