Information supply of expert system for assessing operating modes and technical condition of electrical equipment

The article discusses the issues of information and algorithmic support of the expert system for assessing the operating modes and technical condition of electrical equipment. The peculiarities of the considered diagnostic method is the analysis of diagrams that are highly sensitive to insignificant deviations of the values of the signal parameters (current consumption) from the reference values, as well as stability during the analysis period. The results of computer modeling and experimental research of electrical equipment are described in order to obtain a set of reference diagrams. The possibility of using the method in intelligent systems of electrical equipment real-time monitoring is shown.

Influence of additional dielectric coatings on the electrode surfaces on selected parameters of acoustic emission signals in high-voltage gas insulation systems

The paper is devoted to the study of impact of additional dielectric coatings placed on the surface of the electrodes on the operation of a high-voltage insulation system with air as insulating medium. The study mainly focused on measurement of partial discharges (PDs) with the use of acoustic emission method. Tests were conducted in various levels of chamber pressure. Applicable parameters of recorded signals were analyzed with the use of applications developed in the environment of MATLAB software. The results of analyses clearly show that presence of additional coatings has impact on signal parameters and thus indirectly on PDs. The use of coatings reduces the duration of a single pulse (event) and increases its amplitude. Furthermore, the influence of degradation of the coating caused by individual discharges on the values of the analyzed parameters was analyzed. The study has shown, however, that this effect is negligible.

A Robust Algorithm for Real-Time Phasor and Frequency Estimation under Diverse System Conditions

This paper presents a comprehensive approach for performing phasor and frequency estimation from voltage and/or current signals of the modern power system. Undesirable components, such as decaying DC, if present in the input signal, are first attenuated using a complex-gain filter. The initial estimates of phasor and frequency are obtained next using the discrete Fourier transform and an improved estimation of signal parameters via rotational invariance technique, respectively. Finally, the accuracy of phasor and frequency estimates are increased based on the identified system condition. Simulations performed to evaluate the proposed approach confirm that it can do fast and accurate estimation of phasor and frequency under diverse operating conditions, making it ideal for wide-area monitoring, protection, and control applications in power systems.

Analysis of Errors in Active Power and Energy Measurements Under Random Harmonic Distortion Conditions

As harmonic distortion of voltage and current is reality in the power system, the need for accurate measurement of electrical power and energy goes beyond the instruments’ specifications and calibration procedures regarding pure sine wave signals. Several international standards and recommendations provide test signals for examination of electricity meters under non-sinusoidal conditions, however, not all of the test signal parameters’ possible states are faithfully represented in those documents. Because the high order harmonics may possess random amplitudes and phase shifts in relation to components at fundamental frequency, it is important that the meter’s performance is verified with random waveforms as well. The non-linear dependence between the measured power/energy and the phase shifts, both between fundamental and harmonic components, provides additional complexity of such an analysis. Simple test signals, which are in accordance with the standards’ demands and propositions, are used for determination of the measurement error in case of different harmonic distortion parameter change. In order for a general error function for any measurement device to be determined, mathematical modelling, regarding the results from multiple tests, is performed. The mathematical model presents a strong dependence between a single component’s phase shifts and a meter’s error and it provides a systematization of all signal parameters’ influence on the measurement accuracy.

Passive Localization of Moving Target with Channel State Information

With the popularity of wireless networks and smart devices, wireless signal-based passive target sensing and localization have become a hot research topic and attracted numerous researchers’ interests. The existing passive localization solutions require multiple receivers, which is not practical for real-world applications. In response to this compelling problem, in this paper, we propose a practical single access point-based passive moving target localization system. Concretely, it first utilizes multiple antennas of the access point to form an antenna array and extended antenna, to capture channel state information (CSI) at different spatial locations. Then, leveraging the obtained CSI, the signal parameters, including the angle of arrival (AoA) and time of flight (ToF), are estimated. Based on the estimated signal parameters and the locations of the antenna array and extended antenna, finally, the passive localization of the moving target is realized. Comprehensive experiments are conducted under the real-world scenario with two different test platforms, and the experimental results show the proposed algorithm’s median localization can reach 1.087 m when the number of antennas is 4 and the signal bandwidth is 80 MHz, demonstrating the effectiveness of the proposed algorithm.

Determination of tonal signal parameters based on zero crossing detection

This paper presents a method for identifying tonal signal parameters using zero crossing detection. The signal parameters: frequency, amplitude and phase can change slowly in time. The described method allows to obtain accurate detection using possibly small number of signal samples. The detection algorithm consists of the following steps: frequency filtering, zero crossing detection and parameter reading. Filtering of the input signal is aimed at obtaining a signal consisting of a single tonal component. Zero crossing detection allows the elimination of multiple random zero crossings, which do not occur in a pure sine wave signal. The frequency is based on the frequency of transitions through zero, the amplitude is the largest value of the signal in the analysed time interval, and the initial phase is derived from the moment at which the transition through zero occurs. The obtained parameters were used to synthesise a compensation signal in an active tonal component reduction algorithm. The results of the algorithm confirmed the high efficiency of the method.

DEVELOPMENT OF AN ALGORITHM FOR IDENTIFICATION OF TERRAIN IN A LOWER LIMB PROSTHESIS CONTROL SYSTEM

Статья посвящена разработке алгоритма определения типа местности, по которой перемещается пользователь протезом нижней конечности. Идентификация местности, по которой происходит движение, является важной задачей при управлении протезами нижних конечностей, так как на разных типах местности протез должен совершать разные модели движений. В данном исследовании высказано предположение о возможности определения типа местности с помощью электромиографических датчиков, которые записывают сигналы от определенных мышц пользователя протезом. Чтобы подтвердить это утверждение, было проведено исследование. Испытуемые выполняли несколько типов движений: движение прямо, подъем и спуск по лестнице, подъем и спуск по наклонной поверхности. Электромиографические сигналы регистрировались от разных мышц нижних конечностей испытуемых. После первичной обработки из сигналов были выделены параметры биоэлектрического сигнала, чаще всего используемые в управлении протезами. Результаты исследования показали, что существует статистическая разница в некоторых параметрах сигнала в зависимости от канала регистрации сигнала и типа местности, на которой происходит движение. Исследование доказало возможность определения типа местности по четырем комбинациям параметр сигнала - мышца. На основании полученных результатов предложен алгоритм идентификации местности The article is devoted to the development of an algorithm for determining the type of terrain along which the user moves with a lower limb prosthesis. Identification of the terrain along which the movement takes place is when controlling the prostheses of the lower extremities, since on different types of terrain the prosthesis must perform different models of movements. In this study, it is assumed that it is possible to determine the location using electromyographic sensors that record signals from the muscles of the wearer with a prosthesis. Research has been done to confirm this claim. The subjects performed several types of movements: straight movement, climbing and descending stairs, ascending and descending an inclined surface. Electromyographic signals were recorded from different muscles of the lower end objects. After primary processing, the parameters of the bioelectric signal were extracted from the signals. The research results show that there is a statistical difference in some signal parameters depending on the signal registration channel and the type of terrain on which the movement takes place. The study proved the possibility of determining the type of terrain by four combinations of signal parameter - muscle. Based on the results obtained, an algorithm for identifying the area is proposed