An Analysis of Electromagnetic Disturbances from an Electric Vehicle Charging Station

The electric vehicles (EVs) could potentially have a significant impact on power quality parameters and distribution networks as they are non-linear loads and their charging might result in tremendous power demand. When connected to the utility grid, a large number of EV charging stations from different manufacturers might create significant harmonic current emissions, impact the voltage profile, and eventually affect the power quality. Nevertheless, practical examples of disturbances from charging stations have not been made public. This paper aims to clarify the characteristics of conductive disturbances and levels of current harmonics generated by charging station and their severity on the quality of electric energy. The analysis was based on tests of a prototype station of an EV charging station integrated with a LED street light. The tests concern the determination of current harmonics and the values of conductive electromagnetic disturbances in the 150 kHz–30 MHz range. The test results of the prototype charger with observed exceedances of current harmonics (25th–39th range) and conducted interference exceedances are comprehensively described. After applying filtering circuits to the final version of the station, retesting in an accredited laboratory showed qualitative compliance.

Analysis of Compromising Video Disturbances through Power Line

In this article, we present results on research performed in the TEMPEST domain, which studies the electromagnetic disturbances generated unintentionally by electronic equipment as well as the methods to protect the information processed by this equipment against these electromagnetic phenomena. The highest vulnerability of information leakage is attributed to the display video signal from the TEMPEST domain perspective. Examples of far-range propagation on a power line of this type of disturbance will be illustrated for the first time. Thus, the examples will highlight the possibility of recovering processed information at distances of 1, 10 and 50 m. There are published articles studying electromagnetic disturbances generated by electronic equipment propagating on power cables of such equipment but no studies on their long-distance propagation. Our research aims to raise awareness in the scientific community and the general public of the existence of such vulnerabilities that can compromise confidential or sensitive information that can make the difference between success or failure in the business sector, for example, or can harm personal privacy, which is also important for us all. Countermeasures to reduce or even eliminate these threats will also be presented based on the analysis of the signal-to noise-ratio recorded during our research.

METHOD OF MEASUREMENT AND REDUCTION OF THE ELECTROMAGNETIC DISTURBANCES INDUCTED BY SWITCHING SURGES IN LV CIRCUITS

This paper presents a fast, reliable and portable method for measuring electromagnetic disturbances in LV circuits (overcurrent circuit breakers). The experiment was carried out under conditions reflecting the real measurement environment. The method was verified and confirmed by a series of measurements with passive components reducing the disturbance. The results of the measurements made it possible to obtain suitable EMI reduction solutions, which can be used to protect commutators or end consumers. The results obtained make it possible to apply the method to measurements of multichannel circuit breakers, in which measuring the turn-on time of individual channels is important for the correct operation of the devices.

Numerical modeling of strong effects on ionospheric plasma

В работе представлены постановка задачи начальной стадии мощного антропогенного возмущения ионосферы для последующего вычисления высотно-временного распределения ионосферно-магнитосферных параметров. Данная задача имеет огромное значение в плане теоретического исследования таких возмущений на математических моделях изучаемой среды. Такие возмущения сопровождаются различными физико-химическими процессами, которые к настоящему времени плохо изучены. Основным источником сильных возмущений ионосферы являются мощные электромагнитные излучения (сильная солнечная вспышка, мощный ядерный взрыв). Такие электромагнитные возмущения могут вызывать сильнейшие глобальные перераспределение всей атмосферы Земли, которые к настоящему времени недостаточно надежно изучены, и одним из способов их изучения, является математическое моделирование. Приводится результаты вычислительного эксперимента начальной стадии ионизации нейтрального газа, которые могут помочь в дальнейшем исследовании такого процесса. The paper presents the formulation of the problem of the initial stage of a powerful anthropogenic disturbance of the ionosphere for the subsequent calculation of the altitude-time distribution of the ionosphere-magnetospheric parameters. This problem is of great importance in terms of the theoretical study of such perturbations on mathematical models of the studied environment. Such disturbances are accompanied by various physicochemical processes, which are poorly understood by now. The main source of strong disturbances in the ionosphere are powerful electromagnetic radiation (strong solar flare, powerful nuclear explosion). Such electromagnetic disturbances can cause the strongest global redistribution of the entire atmosphere of the Earth, which by now have not been sufficiently studied reliably, and one of the ways to study them is mathematical modeling. The results of a computational experiment of the initial stage of ionization of a neutral gas are presented, which can help in further investigation of such a process.

Five-State Extended Kalman Filter for Estimation of Speed over Ground (SOG), Course over Ground (COG) and Course Rate of Unmanned Surface Vehicles (USVs): Experimental Results

Small USVs are usually equipped with a low-cost navigation sensor suite consisting of a global navigation satellite system (GNSS) receiver and a magnetic compass. Unfortunately, the magnetic compass is highly susceptible to electromagnetic disturbances. Hence, it should not be used in safety-critical autopilot systems. A gyrocompass, however, is highly reliable, but it is too expensive for most USV systems. It is tempting to compute the heading angle by using two GNSS antennas on the same receiver. Unfortunately, for small USV systems, the distance between the antennas is very small, requiring that an RTK GNSS receiver is used. The drawback of the RTK solution is that it suffers from dropouts due to ionospheric disturbances, multipath, interference, etc. For safety-critical applications, a more robust approach is to estimate the course angle to avoid using the heading angle during path following. The main result of this article is a five-state extended Kalman filter (EKF) aided by GNSS latitude-longitude measurements for estimation of the course over ground (COG), speed over ground (SOG), and course rate. These are the primary signals needed to implement a course autopilot system onboard a USV. The proposed algorithm is computationally efficient and easy to implement since only four EKF covariance parameters must be specified. The parameters need to be calibrated for different GNSS receivers and vehicle types, but they are not sensitive to the working conditions. Another advantage of the EKF is that the autopilot does not need to use the COG and SOG measurements from the GNSS receiver, which have varying quality and reliability. It is also straightforward to add complementary sensors such as a Doppler Velocity Log (DVL) to the EKF to improve the performance further. Finally, the performance of the five-state EKF is demonstrated by experimental testing of two commercial USV systems.

Non-Radial Pulsations of Distorted Stellar Structures: Effect of Mass Variation

Eigen-frequencies (EF) of non–radial modes (NRM) of pulsations of differentially rotating (D R) and tidally distorted (T D) stellar models by considering the effect of mass variation (MV) on its equi-potentials surfaces inside a star. The method utilizes an averaging proposal of Kippenhahn and Thomas (K and T) with conjunction of the concept of Roche-equipotential. The study accolades and corrects earlier studies of non-radial (NR) pulsations of DR and TD stellar structures of different natures such as radial and non-radial oscillations, X-ray, gamma ray and other electromagnetic disturbances. The reflection of the work comes from the requirements of the inclusion of non-uniform densities that yield Lane-Emden equation to have reliable results up to second order disturbances.

Improved Noise Cancelling Algorithm for Electrocardiogram Based on Moving Average Adaptive Filter

The electrocardiogram (ECG) is basic equipment used in the diagnosis of cardiac illness. However, in non-developed countries, most of the population does not have access to medical tests, and many hospitals do not even have these ECGs. On the other hand, the electrical signals generated by the heart and acquired by the ECG have low power and are affected by electromagnetic interference (EMI), mainly produced by the electrical system. Filtering EMI when frequency varies is a challenging task. Within this context, this work aims to produce an easy-to-use low-cost ECG with good electromagnetic disturbances rejection. The proposed noise rejection system is composed of two moving average filters and a phase-locked-loop, namely 2MAV-PLL. The system operates with a low sampling frequency and attenuates the EMI noise present in the ECG signal regardless of the amplitude, obtaining a filtered signal with a 44-dB signal–noise ratio (SNR) between the frequencies of± 10 Hz of the fundamental frequency. Simulation and experimental results prove that the ECG system can attenuate the EMI using relatively low sampling frequency, giving adequate information for health professionals to properly evaluate an electrocardiogram.

Non-Contact High Voltage Measurement in the Online Partial Discharge Monitoring System

The article presents an innovative system for non-contact high voltage (HV) measurement, which extends the measurement capabilities of a portable partial discharges (PD) monitoring system intended for diagnostics of power transformers. The proposed method and the developed measuring system are based on the use of a capacitive probe, thanks to which the high voltage measurement is safe (galvanic separation from the objects at ahigh potential). It is also flexible because the voltage ratio of this system can be configured in a wide range by changing the probe’s position. The proposed solution makes the portable PD monitoring system fully autonomous and independent of the substation systems and devices. The article presents both the concept of the non-contact HV measurement system and its practical implementation. The procedure for determining the voltage ratio and measurement uncertainty, which is at an acceptable level of 1–5% in laboratory conditions, was discussed in detail. In addition, the article discusses the digital filtering and wavelet de-noising methods implemented in the software of the monitoring system, which makes it possible to measure the voltage in the presence of strong electromagnetic disturbances occurring at the substation. Finally, the results of field tests carried out on a 250 MVA power transformer are presented, which confirmed the high accuracy of the HV measurement using a capacitive probe and the advantages of this technique.

Assessment of Conducted Emission for Multiple Compact Fluorescent Lamps in Various Grid Topology

This paper presents the measurement of aggregated conducted emission in the frequency range of 9 kHz to 150 kHz produced by multiple compact fluorescent lamps (CFL) and how it equates to a multiple power converter system. Discrepancies in peak emission measurement results related to this application are illustrated to understand the underlying issue related to volatility of frequency components. Furthermore, this knowledge analyzes the relation of electromagnetic disturbances with respect to different topological network connections. The final presented results constitute theoretical description and statistical information about the characteristics of conducted emission measured in this multi-converter system.