Indonesian Journal of Electrical Engineering and Informatics (IJEEI)
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Wind Power Ramps Analysis for High Shares of Variable Renewable Generation in Power Systems
Get PDFPower system operators should be provided with more information on the characteristics of variable generation power ramps because, although there has been an improvement in the forecasting of wind power, the percentage of error in forecasting is still high to some extent. As a result of the ongoing rise in the participation rate of variable generation, this error will have a significant impact on the balance of power generation and consumption. From the grid operators' viewpoint, in order to balance these ramp events, it is important to get the scale of ramp events in the system as well as the times during which collective events are most likely to arise in order to achieve flexibility and reliability in the power system. Digitization of power systems brings big data which opening opportunities for improving the efficiency of power system operation. This paper analyzes the historical data of power-time curve in two directions: vertical and horizontal, in order to gain details on the behavior of wind power ramps. The method of analysis will be demonstrated by an analysis of actual historical output power of aggregated Belgian wind farms every 15 minutes in 2017 and 2018. Comparing the results of the two years outlined that there are fixed percentages related to wind power ramping behavior and even if the wind capacity is increased, it is possible to determine the extent of these ramps
Circuit Modelling of Bandpass/Channel Filter with Microstrip Implementation
Get PDFThis paper presents a step-by-step approach to the design of bandpass/channel filters. A 3-pole Chebyshev bandpass filter (BPF) with centre frequency of 2.6 GHz, fractional bandwidth of 3%, passband ripple of 0.04321 dB and return loss of 20 dB has been designed, implemented, and simulated. The designed filter implementation is based on the Rogers RT/Duroid 6010LM substrate with a 10.7 dielectric constant and 1.27 mm thickness. The BPF was also fabricated using the same substrate material used for the design simulation. The circuit model and microstrip layout results of the BPF are presented and show good agreement. The microstrip layout simulation results show that a less than 1.8 dB minimum insertion loss and a greater than 25 dB in-band return loss were achieved. The overall device size of the BPF is 18.0 mm by 10.7 mm, which is equivalent to 0.16λg x 0.09λg, where λg is the guided wavelength of the 50 Ohm microstrip line at the filter centre frequency
Impact of Stray Voltage on Renewable Energy-based Farm in Pacific Island Country
Get PDFRecent advancements in solar technology offer an enormous opportunity for the people of Pacific Islands to use electricity from the off-grid solar system for both their energy needs and farming activities. However, a farm’s productivity and animal health might be seriously threatened if it experiences stray voltages caused by the improper grounding of its installed electrical systems. As a shift in the neutral point of an electrical system creates a current flow to the ground through conducting elements, the impacts of stray voltages need to be addressed from both technical and economic viewpoints. In this research, the effects of stray voltages passing through animals are explored using circuit designs for solar sources considering variable grounding resistances due to the different body resistances of various types of animals, and environmental and grounding design issues. A comparison of the stray voltages of two different sources (off-grid solar and traditional grid) with various configurations are conducted to determine their effects on a farm. Finally, their economic impacts together with possible techniques for mitigating them are explained
Analysis and Measurement of Scientific Collaboration Networks Performance
Get PDFCollaboration of scientific research among researchers or universities is very important especially to improve the quality and quantity of the research. It gives the positive impact and very beneficial for both parties so this scientific research network becomes an important component in measuring performance and ranking institutions for national and international levels. The interviews result show that the amount of collaboration alone cannot fair to be used as performance measurement, because in general the successful collaboration can be established to other institutions with higher ranks, which will give a good quality impact to the institution. The purpose of this paper is to propose a new performance measurement formula using case studies in Indonesia. Scientific collaboration networks are generated based on data from lecturers and institutions, especially research outputs indexed in the SINTA-Science and Technological Index. SINTA is the largest and most comprehensive portal for measuring research performance in Indonesia. The formula proposed in this research is to consider the number and weighting based on the score of the institution in the previous year to calculate a new score of the performance of the scientific collaboration network. Implementation results show that Riau Province has the highest collaboration score at the regional level, while the Bandung Institute of Technology as an institution with a score of 46.563 is the highest at the institutional leve
Lightning generated electric field over land and sea at Northern Region of Peninsular Malaysia: Measuring Setup
Get PDFLightning is the transfer of significant charge between two charged object, it can appear between cloud-to-cloud, cloud-to-air and cloud-to-ground. All lightning activities are correlated with charge movement and therefore, it can be studied using measurement of electrostatic field (slow field changes), radiation field (fast field changes) and magnetic field affiliated with charge movement. The measuring equipment was a parallel flat plate and vertical whip antenna with an analog filter buffer circuit, connected to a digital high speed oscilloscope. In principle, both antenna have a similar measuring operation, with the exclusion of the antennas dimension, mode of transient recoder and the association of circuitry characteristic (decay time constant). This measurement setup are commonly used to perform electric field characterization related to various lightning events such as as preliminary breakdown, stepped leader, return stroke, subsequent return stroke, dart leader, dart-stepped leader, narrow bipolar pulses and cloud activity between strokes, such as regular pulse trains, K and M changes and chaotic pulse trains. The measurement systems are located very close to the sea, with respect in obtaining a perspicuous explaination of lightning propagation effects on sea instead on land. Noise-distorted effects in data captured usually introduce in a noisy environment or when the lightning strike far from the measurement station, thus the data gathered from the measurement need to be filter using MATLAB computer simulation before conducting further analysis. A promising wavelet 1-D technique, then, were used in signal denoising process rather using conventional filtration. In this works, the state of art in measuring vertical component of electric field focalized sea area during the thunderstorm days been demonstrate and explained
Classification of Premature Ventricular Contraction (PVC) based on ECG Signal using Convolutional Neural Network
Get PDFThis study observes one of the ECG signal abnormalities, which is the Premature Ventricular Contraction (PVC). Many studies applied a machine learning technique to develop a computer-aided diagnosis to classify normal and PVC conditions of ECG signals. The common process to obtain information from the ECG signal is by performing a feature extraction process. Since the ECG signal is a complex signal, there is a need to reduce the signal dimension to produce an optimal feature set. However, these processes can remove the information contained in the signal. Therefore, this study process the original ECG signal using a Convolutional Neural Network to avoid losing information. The input data were in the form of both one beat of normal ECG signal or PVC with size 1x200. The classification used four layers of convolutional neural network (CNN). There were eight 1x1 filters used in the input. Simultaneously, 16 and 32 of 1x1 filters were used in the second and the fourth convolutional layers, respectively. Thus the system produced a fully connected layer consisted of 512 neurons, while the output layer consisted of 2 neurons. The system is tested using 11361 beats of ECG data and achieved the highest accuracy of 99.59%, with the 10-fold cross-validation. This study emphasizes an opportunity to develop a wearable device to detect PVC since CNN can be implemented into an embedded system or an IoT based system
Truncated Microstrip Patch Antenna with DGS Based on Double Looped CSRR Arrays for Enhancement of Bandwidth
Get PDFThis paper presents a novel method for the design of truncated microstrip patch antenna with DGS based on Double Looped CSRR arrays for enhancement of bandwidth. The proposed antenna is suitable for WLAN/Wi-Fi, RFID applications. A truncated microstrip patch antenna without DGS was initially designed for a resonant frequency of 2.86GHz having a bandwidth of 95.6MHz. By integrating a new Double Looped CSRR array (DLCSRR) structure on the ground plane, resonant frequency of the antenna is shifted to 2.47GHz and also the bandwidth is enhanced to 202.5MHz. By implementing DLCSRR array structure on the ground plane size reduction and bandwidth enhancement of 52.79% is achieved. The performance of truncated microstrip patch antenna with DGS based on Double Looped CSRR array structure was also compared by replacing conventional proximity fed microstrip patch antenna with the same physical size. The conventional proximity coupled microstrip patch antenna is designed for a resonant frequency of 2.26GHz with a lower bandwidth of 23.3MHz.The antennas were designed using CST simulation software. The measurement result shows a good agreement with simulated results
Improvement of alzheimer disease diagnosis accuracy using ensemble methods
Get PDFNowadays, there is a significant increase in the medical data that we should take advantage of that. The application of the machine learning via the data mining processes, such as data classification depends on using a single classification algorithm or those complained as ensemble models. The objective of this work is to improve the classification accuracy of previous results for Alzheimer disease diagnosing. The Decision Tree algorithm with three types of ensemble methods combined, which are Boosting, Bagging and Stacking. The clinical dataset from the Open Access Series of Imaging Studies (OASIS) was used in the experiments. The experimental results of the proposed approach were better than the previous work results. Where the Random Forest (Bagging) achieved the highest accuracy among all algorithms with 90.69%, while the lowest one was Stacking with 79.07%. All these results generated in this paper are higher in accuracy than that done before
Web Application Reinforcement via Efficient Systematic Analysis and Runtime Validation (ESARV)
Get PDFSecuring the data, a fundamental asset in an organization, against SQL Injection (SQLI), the most frequent attack in web applications, is vital. In SQLI, an attacker alters the structure of the actual query by injecting code via the input, and gaining access to the database. This paper proposes a new method for securing web applications against SQLI Attacks (SQLIAs). It contains two phases based on systematic analysis and runtime validation and uses our new technique for detection and prevention. At the static phase, our method removes user inputs from SQL queries and gathers as much information as possible, from static and dynamic queries in order to minimize the overhead at runtime. On the other hand, at the dynamic phase, the prepared information alongside our technique are used to check the validity of the runtime query. To facilitate the usage of our method and show our expectations in practice, ESARV was implemented. The empirical evaluations demonstrated in this paper, indicate that ESARV is efficient, accurate, effective, and also has no deployment requirements
Integral Backstepping Based Nonlinear Control for Maximum Power Point Tracking and Unity Power Factor of a Grid Connected Hybrid Wind-Photovoltaic System
Get PDFThis paper proposes a novel integral backstepping-based nonlinear control strategy for a grid-connected wind-photovoltaic hybrid system. Firstly, detailed three-phase models of the hybrid system elements are presented, and then an overall state-space model is derived. Secondly, nonlinear control laws for the hybrid system’s converters are developed with the aim of ensuring maximum extraction of the available renewable energy, stabilizing the DC bus voltage and guaranteeing the operation of the hybrid system at unity power factor. The overall stability of the closed-loop system is demonstrated on the basis of Lyapunov’s stability theory. Comprehensive simulations, using the MATLAB/Simulink software environment, are carried out to assess the effectiveness of the proposed control methodology. The simulation results obtained confirm that the proposed control strategy offers high efficiency in various operating modes of the hybrid generation system