Doaa Khalil Ibrahim

As the building sector has the largest share of energy consumption in most countries of the world, this paper focused on the study of one of the most important of the buildings which are the airports. Airports can play a major role in reducing the burden on the electrical grid as they have several factors that make them optimum models for applying energy efficiency strategies. Accordingly, the contribution in this paper is achieved by applying a Fuzzy Logic Control (FLC) scheme to improve the energy efficiency of the Egyptian airports without compromising the comfort level of the occupants and validating the obtained results by the aid of ―DesignBuilder‖ software conducted with the ―EnergyPlus‖ simulator, which is a state-of-the-art 3D simulator tool for checking building energy, carbon, lighting, and comfort performance. The applied 3D simulator evaluates the impacts of implementing the proposed fuzzy control system instead of ON/OFF control schemes or Building Management System (BMS). In this context, case studies were conducted at three different Egyptian airports as a high, medium, and low occupancy level airports respectively to discuss the opportunities and challenges of applying the fuzzy logic scheme in airports according to the occupancy level.

Sympathetic tripping is a common challenge that affects the proper operation of the earth fault relays in distribution networks. It likely occurs when healthy feeders are exposed to an unnecessary trip operation in response to an actual fault occurring on an adjacent feeder. The sympathetic tripping phenomena of overcurrent and earth fault (EF) relays in the distribution networks and their causes are studied in this paper. Real recorded data of affected healthy feeder(s) for different sympathetic trip scenarios reported from an Egyptian distribution network are extensively analysed. A custom logic protection scheme is proposed to detect the sympathetic tripping phenomena using the existing features of IED relays without any additional cost. In addition to the captured real disturbance records, simulated scenarios of sympathetic tripping are modelled using MODELS language in ATP/EMTP program to evaluate the proposed schemes. The achieved results ensure the suitability of the proposed protection program in order to avoid the unnecessary false sympathetic tripping for both incoming and outgoing feeders.

High impedance faults (HIFs) are difficult to detect by conventional protection devices such as distance and
overcurrent relays. This paper presents a scheme for high impedance fault detection in extra high voltage transmission line by recognizing the distortion of the voltage waveforms caused by the arcs usually associated with HIFs. The proposed scheme is based on combined wavelet transform and Prony’s method. The discrete wavelet transform (DWT) based analysis, yields three phase voltages in the high
frequency range which are fed to a classifier for pattern recognition and also fed to the Prony’s method for correct discriminating of switching with and without fault cases. The classifier is based on an algorithm that uses a recursive method to sum the absolute values of the high frequency signal generated over one cycle by shifting one sample, while switching cases discrimination is based on Prony’s amplitude changing
with time. Characteristics of the proposed fault detection scheme are analysed by extensive simulation studies that clearly reveal that the proposed scheme can accurately detect HIFs in the EHV transmission lines. Results of extensive simulations using ATP/EMTP on 500 kV Egyptian transmission line clearly reveal that the proposed scheme can accurately detect HIFs in the EHV transmission lines systems as well as its ability to discriminate clearly between HIFs and various switching conditions.

This paper presents a fault location scheme for transmission systems consisting of an overhead line combined with an underground power cable. The algorithm requires phasor measurements data from one end of the transmission line and the synchronized measurements at the most far end of the power cable. Fault location is derived using distributed line model, modal transformation theory and Discrete Fourier Transform. The technique can be used on-line or off-line using the data stored in the digital fault recording apparatuses. The proposed scheme has the ability to locate the fault whether it is in the overhead line or in the underground power cable. In addition to, the proposed scheme gives an accurate estimation of the fault resistance at fault location. Extensive simulation studies carried out using MATLAB show that the proposed scheme provides a high accuracy in fault location under various fault conditions.