A Two-Stage ADALINE for Harmonics and Interharmonics Measurement

The interharmonic group concept adopted by the IEC 61000-4-7 is very useful for addressing the need to monitor interharmonics in power systems. This paper shows that grouping spectral bins into interharmonics and harmonic components of 5Hz resolution could yield misleading information for cases where an interharmonic component's frequency is very close to a harmonic frequency. Since interharmonics in such cases can cause more severe waveform modulation, the interharmonic grouping scheme needs to be improved. A signal processing method that can separate interharmonic and harmonic components in close proximity is, therefore, proposed in this paper to address this need. Field data analysis showed that the proposed method was able to extract interharmonic and harmonic components correctly.

In this research work, a multiple synchronous reference frame (MSRF) based analysis method used together with exponential smoothing (ES) to accurately obtain the time-varying harmonics and interharmonics of electric arc furnace (EAF) currents, is proposed. The proposed method has been implemented on NVIDIA Geforce GTX 960 graphics card for the parallel processing of all harmonics and interharmonics so that real-time processing of the EAF currents obtained from a measurement point of the electricity transmission system is possible. To obtain the best possible accuracy for the EAF current harmonics and interharmonics estimation, the ES window size has been optimized specific to each harmonic and interharmonic frequency component. It has been shown on field data that the implemented system is capable of successfully estimating all harmonics up to the 50th and all interharmonics at 5Hz resolution in real-time. Moreover, active filtering of certain harmonics and interharmonics has been achieved in the simulation environment and it has been shown that successful real-time filtering of any harmonic and interharmonic component is possible with the proposed MSRF+ES method. Hence, it can be concluded that the proposed system can be used to generate reference signals for the controllers of the new technology compensation systems such as active power filters.

A PC-based instrument for harmonics and interharmonics measurement in power supply systems

Fast Fourier transform (FFT) has been widely used for the signal processing because of its computational efficiency. Most power quality meters and digital relays adopt FFT-based algorithm to characterize harmonics of the measured signals. A direct application of FFT-based algorithms may lead to inaccurate results, if the system fundamental frequency varies or interharmonics are present. This paper proposes a modified algorithm of FFT for harmonics and interharmonics measurements. The performance of the proposed algorithm is then validated by testing the simulated and actual measured signals. Results are compared with those obtained by the direct application of a conventional FFT algorithm without corrections. It shows that the solutions obtained by the proposed algorithm are more accurate with reasonable computational time.

In order to represent hierarchical information more efficiently and aesthetically on mobile devices, many researchers have adopted the space-filling method—Treemap. In this article, a novel dynamic hierarchical-layout algorithm is proposed to visualize hierarchical information on mobile devices. This layout algorithm tries to represent the hierarchical data set with more balanced aspect ratio for the rectangles which is closely related to the aesthetics of treemap. Furthermore, a focus+context fisheye distortion algorithm is introduced to help users understand details by increasing the size of the interested items while decreasing the others. Experimental results show that the proposed method can provide a suitable resolution for visualizing hierarchical information with high efficiency and give focus+context views on mobile devices in real time.

The methods of modelling of power system modes and of testing of relay protection devices with the aid the simulation complexes in real time and with the help of computer software systems that enables the simulation of virtual time scale are considered. Information input protection signals in the simulation of the virtual model time are being obtained in the computational experiment, whereas the tests of protective devices are carried out with the help of hardware and software test systems with the use of estimated input signals. Study of power system stability when modes of generating and consuming electrical equipment and conditions of devices of relay protection are being changed requires testing with the use of digital simulators in a mode of a closed loop. Herewith feedbacks between a model of the power system operating in a real time and external devices or their models must be determined (modelled). Modelling in real time and the analysis of international experience in the use of digital simulation power systems for real-time simulation (RTDS simulator) have been fulfilled. Examples are given of the use of RTDS systems by foreign energy companies to test relay protection systems and control, to test the equipment and devices of automatic control, analysis of cyber security and evaluation of the operation of energy systems under different scenarios of occurrence of emergency situations. Some quantitative data on the distribution of RTDS in different countries and Russia are presented. It is noted that the leading energy universities of Russia use the real-time simulation not only to solve scientific and technical problems, but also to conduct training and laboratory classes on modelling of electric networks and anti-emergency automatic equipment with the students. In order to check serviceability of devices of relay protection without taking into account the reaction of the power system tests can be performed in an open loop mode with the use of hardware and software test systems. Testing methods for relay protection and their models in open-loop mode have been proposed.

With the development and introduction of intelligent electronic devices within the classical electrical grids and their transformation into smart grids, emerged the need for extracting and processing the data from those devices in real time or near real time. In addition to information extraction, it is necessary for field devices to be able to communicate with each other as well as with a central command point. By integrating internet of thing (IoT) within smart grids communication between devices that normally were not designed to exchange information becomes possible, information that can be accessed from anywhere with Internet access. This paper will explore the benefits brought by IoT application to the smart grid.

Introduction: The production of Waste Electrical and Electronic Equipment (WEEE) has grown rapidly in recent years. It is necessary to determine the amount of them for its effective management. The aim of this study was to determine the amount of WEEE stored in the houses of Yazd citizens and the level of Knowledge, Attitude and Practice (KAP) of citizens regarding WEEE management. Materials and Methods: This descriptive, cross-sectional study was carried out using random sampling on 300 Yazdian citizens. To determine the amount of WEEE stored in houses and the level of KAP of people regarding WEEE, was used a researcher-made questionnaire whose validity and reliability were confirmed and data analysis was performed using nonparametric tests in SPSS. Results: The amount of WEEE in the study population was 21.8 metric tons was obtained. Of these, the highest amount of waste was related to the refrigerator with 3.9 metric tons and the highest number of used equipment stored was related to cell phone, with 285 units. The levels of knowledge (with a mean score of 5.06 ± 2.5), attitude (with a mean score of 43.37 ± 5.21), and practice (with a mean score of 10.71 ± 2.95) were respectively in moderate, good and moderate conditions. Conclusion: Given planning by the Waste Organization leads to job creation, access to valuable raw materials, and environmental protection. With increasing knowledge about the proper use of electronic and electrical equipment, their useful life can be increased and the process of their conversion to waste can be extended.

Business process modeling is one of the most important steps in managing the lifecycle of a business process. A digital twin of a business process is a virtual model of a business process designed to replicate the behavior of a real business process. The difference between a digital twin and a business process simulation is that the simulation does not require real-time data, while a digital twin is created based on real-time data. A digital twin comprises a physical entity in the real world, a software-based digital counterpart, and the data that links them both. When a created process communicates in real time with IoT devices and adapts its execution based on the information received in real time, this is referred to as a process digital twin. As the field of digital twins becomes increasingly popular, the challenge is to investigate how the process digital twin communicates with IoT devices in real time and updates its execution state.

The Internet of Things (IoT) contains sets of hundreds of thousands of network-enabled devices communicating with central controlling nodes or information collectors. The correct behaviour of these devices can be monitored by inspecting the traffic that they create. This passive monitoring methodology allows the detection of device failures or security breaches. However, the creation of hundreds of thousands of traffic time series in real time is not achievable without highly optimised algorithms. We herein compare three algorithms for time-series extraction from traffic captured in real time. We demonstrate how a single-core central processing unit (CPU) can extract more than three bidirectional traffic time series for each one of more than 20,000 IoT devices in real time using the algorithm DStries with recursive search. This proposal also enables the fast reconfiguration of the analysis computer when new IoT devices are added to the network.

The measurement of Power Quality (PQ), generally performed at Low Voltage (LV) level, is gaining more and more importance also at the Medium Voltage (MV) level, due to the increasing presence of switching power converters (both loads or generators) directly connected to MV grids. In this case, the use of Voltage Transformers (VTs) is unavoidable to scale voltage down to amplitudes compatible with the input ranges of PQ instruments. However, the current absence of an international standard dealing with VTs used for PQ measurements leaves the manufacturers and the users in a situation of complete uncertainty, since different products can have performance specifications tested and stated in completely different ways. This paper aims at defining an integrated approach for the evaluation of VTs accuracy used for PQ measurements, focusing on harmonics and interharmonics. The paper provides experimental results of the tests performed on a MV inductive VT according to the proposed procedure. As a result, it is demonstrated that VT accuracy in the measurement of a specific phenomenon should be evaluated with complex waveforms including the contemporary presence of different PQ phenomena.

Dense frequency signal refers to the signal containing harmonic and interharmonic components that are very close to each other in frequency domain. Due to the limited frequency resolution and the existence of spectrum leakage and fence effects, it is difficult to accurately detect the harmonic and interharmonic components in dense frequency signals. The spectral interference under asynchronous sampling conditions can lead to the failure of measuring the multiple adjacent harmonics and interharmonics. Therefore, this article proposes a mixed dense signal harmonic and interharmonic analysis method. The dense frequency signal model is first established. Based on the model, the discrete Fourier transform results of the dense frequency signal are processed by local mean decomposition extension to construct that single multichannel signal as a virtual multichannel. Then, the parameters of each frequency component are obtained by means of principal component analysis and fast independent component analysis. Finally, the measurement of dense harmonic and interharmonic components is implemented. The simulation and experimental results show the high accuracy and the noise resistance ability of the proposed method in identifying and measuring the dense harmonic and interharmonic components.

This paper studies the effects of the most commonly used window functions, rectangular and Hanning windows, on the processing of harmonics and interharmonics in power system in the framework of the standards defined by the International Electrotechnical Commission. The effect of the two window functions on the processing of fluctuating harmonics and interharmonics is studied. The effect of spectral leakage due to synchronization errors with the window width in the determination of the harmonic and interharmonic groups and subgroups using both windows, is also considered in the paper. From the results obtained it can be concluded that in the new IEC standard framework, the rectangular window is the most appropriate window function for a harmonic and interharmonic measurement instrumentation any measurement conditions

Stereoelectroencephalography (SEEG) is becoming more prevalent as a planning tool for surgical treatment of intractable epilepsy. Stereoelectroencephalography uses long, thin, cylindrical "depth" electrodes containing multiple recording contacts along each electrode's length. Each lead is inserted into the brain percutaneously. The advantage of SEEG is that the electrodes can easily target deeper brain structures that are inaccessible with subdural grid electrodes, and SEEG does not require a craniotomy. Brain-machine interface (BMI) research is also becoming more common in the Epilepsy Monitoring Unit. A brain-machine interface decodes a person's desired movement or action from the recorded brain activity and then uses the decoded brain activity to control an assistive device in real time. Although BMIs are primarily being developed for use by severely paralyzed individuals, epilepsy patients undergoing invasive brain monitoring provide an opportunity to test the effectiveness of different invasive recording electrodes for use in BMI systems. This study investigated the ability to use SEEG electrodes for control of 2D cursor velocity in a BMI. Two patients who were undergoing SEEG for intractable epilepsy participated in this study. Participants were instructed to wiggle or rest the hand contralateral to their SEEG electrodes to control the horizontal velocity of a cursor on a screen. Simultaneously they were instructed to wiggle or rest their feet to control the vertical component of cursor velocity. The BMI system was designed to detect power spectral changes associated with hand and foot activity and translate those spectral changes into horizontal and vertical cursor movements in real time. During testing, participants used their decoded SEEG signals to move the brain-controlled cursor to radial targets that appeared on the screen. Although power spectral information from 28 to 32 electrode contacts were used for cursor control during the experiment, post hoc analysis indicated that better control may have been possible using only a single SEEG depth electrode containing multiple recording contacts in both hand and foot cortical areas. These results suggest that the advantages of using SEEG for epilepsy monitoring may also apply to using SEEG electrodes in BMI systems. Specifically, SEEG electrodes can target deeper brain structures, such as foot motor cortex, and both hand and foot areas can be targeted with a single SEEG electrode implanted percutaneously. Therefore, SEEG electrodes may be an attractive option for simple BMI systems that use power spectral modulation in hand and foot cortex for independent control of 2 degrees of freedom.

Previously, most mammalian auditory systems research has concentrated on human sensory perception whose frequencies are lower than 20 kHz. The implementations almost always used analog VLSI design. Due to the complexity of the model, it is difficult to implement these algorithms using current digital technology. This paper introduces a simplified model of biosonic reception system in bats and its implementation in the ‘‘Chiroptera Inspired Robotic CEphaloid’’ (CIRCE) project. This model consists of bandpass filters, a half-wave rectifier, low-pass filters, automatic gain control, and spike generation with thresholds. Due to the real-time requirements of the system, the system employs Butterworth filters and advanced field programmable gate array (FPGA) architectures to provide a viable solution. The ultrasonic signal processing is implemented on a Xilinx FPGA Virtex II device in real time. In the system, 12-bit input echo signals from receivers are sampled at 1 M samples per second for a signal frequency range from 20 to 200 kHz. The system performs a 704-channel per ear auditory pipeline operating in real time. The output of the system is a coded time series of threshold crossing points. Comparing hardware implementation with fixed-point software, the system shows significant performance gains with no loss of accuracy.