Applied Mechanics and Materials Vols. 752-753

Abstract: To solve the reliability assessment challenge of protection channels caused by elements multiplexing. The paper build a weighted-undirected graph of optical fiber protection channels, whose nodes measurement is SDH reliability and reliability of optical fiber as edge weights. Start from the information provided by the actual grid, encode the data according to the most close to the actual data format, developed an algorithm for channels and services reliability assessment based on logical "or" and "exclusive or". The result is verified in a 9-node and 19-channel network in central China Grid, showing that the proposed encoding method and model have good practicability and operability, which can offer grid reference to network optimization, scientific channels arrangement and the maintenance of the protection channels.

Abstract: Problematic issues insulation of power cable systems (PCS) based on the design and development of non-destructive methods are considered in the paper. The basic components of the PCS, destroying the insulation, are determined. The analytical method for assessing the oxidation processes of cellulose with the definition of the most probable is proposed. The approach for identifying the main processes of destruction of the insulation allows more detail to present background to the development of partial discharges (PD) in insulation and to identify measures for minimizing processes that lead to the destruction of the insulation PCS.

Abstract: Power quality has become a greater concern nowadays. The increasing number of power electronics equipment contributes to the poor quality of electrical power supply. The power quality signals will affect manufacturing process, malfunction of equipment and economic losses. This paper presents the verification analysis of power quality signals classification system. The developed system is based on linear time-frequency distribution (TFD) which is spectrogram that represents the signals jointly in time-frequency representation (TFR). The TFD is very appropriate to analyze power quality signals that have magnitude and frequency variations. Parameters of the signal such as root mean square (RMS) and fundamental RMS, total waveform distortion (TWD), total harmonic distortion (THD) and total non-harmonic distortion (TnHD) of voltage signal are estimated from the TFR to identify the characteristics of the signal. Then, the signal characteristics are used as input for signal classifier to classify power quality signals. In addition, standard power line measurements are also calculated from voltage and current such as RMS and fundamental RMS voltage and current, real power, apparent power, reactive power, frequency and power factor. The power quality signals focused are swell, sag, interruption, harmonic, interharmonic, and transient based on IEEE Std. 1159-2009. The power quality analysis has been tested using a set of data and the results show that, the spectrogram gives high accuracy measurement of signal characteristics. However, the system offers lower accuracy compare to simulation due to the limitation of the system.

Abstract: Voltage source inverter (VSI) plays an important roles in electrical drive systems. Consistently, expose to hash environmental condition, the lifespan of the electronic component such as insulated-gate bipolar transistor (IGBT) may shorten and many faults related to the inverter especially switches can be occur. The present of VSI switches faults causing equipment failure and increased the cost of manufacturing process. Therefore, faults detection analysis is mandatory to identify the VSI switches faults. This paper presents the analysis of VSI switches faults using time-frequency distributions (TFDs) which are short times Fourier transform (STFT) and spectrogram. From time-frequency representation (TFR) obtained by using the TFDs, parameters of the faults signal are estimated such as instantaneous of average, root mean square (RMS), fundamental, Total Waveform Distortion (TWD), Total Harmonics Distortion (THD) and Total non-Harmonic Distortion (TnHD) of current signals. Then, based on the characteristics of the faults calculated from the signal parameters, VSI switches faults can be detected and identified. The performance of TFD for the faults analysis is also demonstrated to obtain the best TFD for switches faults detection and identification system. The results show that, STFT is the best technique to classify and identify VSI switches faults and can be implemented for automated system.

Abstract: This paper presents the transient instantaneous voltage sag analysis of distributed generation (DG) in distribution system. The behavior of voltage sag is analyzed by using DigSILENT power factory software (DPFS). As affected by unsymmetrical fault of feeder 2, the calculation of initial condition carries out through instantaneous values (electromagnetic transients). The simulation results show that instantaneous voltage sag affects the DG and operation of electrical equipment. The phase short circuit affects the voltage waveform, varies from the original waveform and caused the flicker transient problem.

Abstract: The objective of this study was to investigate the efficiency of the CO₂ control ventilation to enhance energy saving compared with constant air ventilation (CAV) approach of air conditioner. To this end, a small air-conditioner room of 20 square meters was used as the testing room. A carbon dioxide (CO₂) sensor was installed inside to measure indoor air quality while two enthalpy sensors were installed both inside and outside for indoor and outdoor air enthalpies online monitoring. The algorithm of CO₂ control ventilation used is to compare the CO₂ difference between inside and setpoint; when the inside CO₂ concentration is lower than the setpoint, the controller will sent a signal to stop the fresh air intake and exhaust air fans. Measurement were conducted for three indoor temperature set points namely 24, 25 and 26 ^oC. The indoor CO₂ level was set at 900 ppm, 800 ppm, 700 ppm and 600 ppm The results of measured electrical power consumption showed that CO₂ approach when compared to the CAV approach could save 21.82%, 18.28%, 2.26% and 0.45% and ventilator save 64.19%, 53.4%, 16.8% and 1.26%, for the four CO₂ concentration indoor setpoints considered respectively. Simple mathematical relationships were also derived to estimate the energy saving using the CO₂ control ventilation. This CO₂ control ventilation could be mainly applied for the air condition room of Thailand.

Abstract: Long-term heat accumulation is one of the possibilities to reduce the energy consumption of buildings. It can also be categorized as renewable energy because of the accumulation should be generated from solar transformation through solar collectors. There are many ways to conserve energy and each of them has a lot of advantages and disadvantages. The article focuses primarily on dry, sprinkled underground storages called STES especially in terms of design.

Abstract: High concentrations of CO₂ are one of the causes of imperfect oxygenation of the blood circulation in humans. An experimental measurement of a passive home during a simulated power outage was carried out from July 7-15^th 2014. In the measured rooms (one with plants with leaves the size of one of the bigger participants in this project, the second room without any plants at all), the levels of CO₂ were observed, as well as the levels of relative air humidity of the interior, and the interior temperature. The measurement was carried out at night, when sleeping time was simulated, i.e. the resting period. The impact of plants did not significantly influence the CO₂ reduction in the interior of the building. Regular airing is necessary for maintaining the hygienic limit of the concentration of CO_2. It is thus necessary to ensure this with the windows open during an unexpected power outage.

Abstract: Since automatic control is used in every field, there is almost no industrial application system which doesn’t employ the sensors. It makes correctly reading the data obtained from sensors in the system with sensors and transmitting this data into the computer more important. In this executed study, a design for an interface which can be easily used with a low cost data processing card and with flexible structure was performed. In the executed system, the PIC18F4550 microcontroller was used and data can be accurately read from 10 different channels. The data read from the designed data acquisition card was transferred into a computer interface program prepared in C# program using a USB and recorded into the database in the Microsoft Access program. The designed interface, the values of read signals and their graphs may be displayed on the screen. Thus, the interface screen may be used as both an indicator and oscilloscope screen.

Abstract: Soil represents a decisive natural resource and economic and eco-social potential of the every country. Soil pollution is one of the biggest environmental problems. Contamination in the soil environment has a significant impact on the use of land resources and can cause high levels of exposure for people living near the site of contamination. Therefore, the risk elements soil pollution assessment is one of the most important resources for comprehensive evaluation of contaminated areas.The paper investigates the degree of heavy metal contamination of agricultural soil in selected Slovakian districts over a monitored period of time. Selected multidimensional statistical methods were applied to analyse and evaluate the degree of soil contamination.