Publications

Export 127 results:
Sort by: Author Title [ Type  (Asc)] Year
Journal Article
El-Nagar, M. M. K., D. K. Ibrahim, and H. K. M. Youssef, "Optimal Harmonic Meter Placement Using Particle Swarm Optimization Technique", Online J. Power and Energy Engineering, vol. 2(2), pp. 204-209, 2011, 2011. Abstract
n/a
Alham, M. H., M. Elshahed, D. K. Ibrahim, and E. E. D. A. El Zahab, "Optimal operation of power system incorporating wind energy with demand side management", Ain Shams Engineering Journal, vol. 8, issue 1: Elsevier, pp. 1-7, 2017. AbstractWebsite

The high penetration of the wind energy in the power systems raises some issues such as ramping and mismatch between the wind power and power demand. One of the possible solutions to these issues is the demand side management (DSM). In this paper, dynamic economic dispatch (DED) incorporating different penetration levels of wind energy and utilizing the DSM is proposed to solve the issues related to high penetration of wind energy. The effect of utilizing the DSM on the operation cost with different test cases is discussed. The General Algebraic Modeling System (GAMS) using BARON as a solver and genetic algorithm (GA) with hybrid function are used to solve the proposed DED model and a comparison between them is assessed. The proposed model is applied to a six units’ generation system to test the effectiveness of the proposed model.

Zeineldin, H. H., H. M. Sharaf, D. K. Ibrahim, and E. E. - D. AbouEl-Zahab, "Optimal Protection Coordination for Meshed Distribution Systems With DG Using Dual Setting Directional Over-Current Relays", IEEE Transactions on Smart Grid, vol. 6, no. 1: IEEE, pp. 115–123, 2015. AbstractWebsite

In the presence of distributed generation (DG), it is important to assure a fast and reliable protection system for the distribution network to avoid unintentional DG disconnection during fault conditions. In this paper, dual setting directional over-current relays are proposed for protecting meshed distribution systems with DG. Dual setting relays are equipped with two inverse time-current characteristics whose settings will depend on the fault direction. The protection coordination problem for the dual setting directional relay is formulated as a nonlinear programming problem where the objective is to minimize the overall
time of operation of relays during primary and backup operation.
The proposed protection coordination scheme using dual setting relays is compared against the conventional approach, which relies on the conventional one setting directional relay. The proposed scheme is applied to the power distribution network of the IEEE 30-bus system equipped with synchronous and inverter-based DG. The results show that the proposed protection coordination scheme with dual setting relay can significantly reduce the overall relay operating time, making it an attractive option for distribution systems with DG.

Gamal Mohamed, R., D. K. Ibrahim, H. Kamal Youssef, and H. H. Rakha, "Optimal Sizing and Economic Analysis of Different Configurations of Photovoltaic systems", International Review of Electrical Engineering, vol. 9, issue 1: Praise Worthy Prize, pp. 146-156, 2014. Abstract

This paper presents a comparative study between different configurations of photovoltaic (PV) systems which are the stand-alone (PV) system, the PV-diesel- battery hybrid system and the grid connected PV system. The main objective is to select the optimal system configuration for supplying the electrical load of an Egyptian isolated village. Design calculations are carried out using three different techniques which are: Heuristic approach, loss of power supply probability indices, and HOMER software analysis. The life cycle cost (LCC) analysis is also conducted to assess the economic viability of designed system. As for determining the optimal PV panels tilt angle, three cases are studied. The paper also shows the effect of electricity price on PV standalone system, and grid extension.

Gamal Mohamed, R., D. K. Ibrahim, M. M. Abdel Aziz, and H. Rakha, "Optimal Sizing and Economic Analysis of Stand-Alone Photovoltaic System", International Journal on Power Engineering and Energy, IJPEE, vol. 4, issue 2, pp. 378-384, 2013. AbstractWebsite

For the development of energy sources in rural regions in Egypt at the brink of the 21st century, it may be necessary to use solar energy in all applications as one of the most promising new, clean and renewable energy sources. This paper presents a study for a stand-alone photovoltaic (PV) system design to provide the required electricity for an isolated village in Mersa Matrouh, Egypt. The complete design of the suggested system is achieved by optimization techniques using different software. In addition to taking into account site radiation data and electrical load data of this typical village, the life cycle cost (LCC) analysis is also conducted to assess the economic viability of the designed system.

Soliman, A., D. K. Ibrahim, and O. E. Gouda, "Parameters affecting the arcing time of HVDC circuit breakers using black box arc model", IET Generation, Transmission & Distribution, vol. 13, issue 4, pp. 461 – 467, 2019. AbstractWebsite

Arc interruption of high voltage direct current (HVDC) circuit breakers (CBs) is one of the main challenging factors for using HVDC grids. To evaluate the arc interrupting capability in HVDC CBs, black box arc models are used to represent the nonlinear arc conductance depending on Cassie and Mayr dynamic arc equations. Extensive simulation studies are carried out to investigate the effect of controlled and uncontrolled parameters on the CB arcing time. A real line represents a part of 500 kV electrical connection systems between Egypt and the Kingdom of Saudi Arabia is simulated to be a faulty load. It is found that the arcing time of the HVDC CB can be reduced by increasing the value of cooling power coefficient (p) and decreasing the value of arc time constant (τ). It is also deduced that the arcing time is reduced by the increase of the commutation capacitance value (C) and decreasing the commutation inductance (L) value and vice versa. Moreover, it is concluded that the arcing time is greatly affected by the fault location and the fault arc resistance (Rf) according to fault conditions.

Boghdady, T. A., I. A. Sweed, and D. K. Ibrahim, "Performance Enhancement of Doubly-Fed Induction Generator-Based-Wind Energy System", International Journal of Renewable Energy Research, vol. 13, issue 1, pp. 311-325, 2023. AbstractWebsite

Nowadays, the challenging errand is enhancing the wind energy system (WES) performance to be more competitive and economically viable. One of the best ways to enhance the performance of the doubly-fed induction generator (DFIG)-based-WES is the optimization of the proportional-integral (PI) controllers for the variable frequency converter system. Many objectives with different optimization techniques have been used in literature to achieve optimal performance. Each choice has its advantages and disadvantages. This paper presents a new design approach for better performance of PI controllers and, hence DFIG over a wide range of operating conditions through two main themes. The first is by introducing a new multi-objective formulation, while the second is utilizing recent optimization techniques like Grey Wolf Optimizer and Whale Optimization Algorithm. Four PI controllers are optimized using a traditional objective function and the proposed multi-objective formulation. Two are related to the Rotor Side Converter (RSC), named power regulator, and the main rotor side converter current regulator. The other two PI controllers related to Grid Side Converter (GSC) are the DC-link voltage regulator and the main grid-side converter current regulator. A performance comparison is held through normal and abnormal operating conditions on a simulation model of a 6 MW wind farm located in Jabal Alzayt along the Red Sea Coast in Egypt and directly connected to the grid. The results confirmed the effectiveness of the proposed approach to help the DFIG-based-WES to agree with the Egyptian Grid Code during disturbances compared with the traditional objective formulation.

Abdel Aziz, M. M., E. S. T. E. Din, D. K. Ibrahim, and M. Gilany, "A phasor-based double ended fault location scheme for aged power cables", Electric Power Components and Systems, vol. 34, issue 4: Taylor & Francis, pp. 417-432, 2006. AbstractWebsite

This paper presents a fault location scheme for aged power cables using phasor measurements from both ends of the cable line. The proposed fault location scheme is derived using two-terminal measurements incorporated with a distributed line model, modal transformation theory, and discrete Fourier transforms. The proposed scheme can solve the problem of cable changing parameters, especially the change of the relative permittivity and thus for the operating positive, negative, and zero sequence capacitance changes. Extensive simulation studies are carried out using the alternative transients program ATP/EMTP. The simulation studies show that the proposed scheme provides a high accuracy in fault location calculations under various system and fault conditions. The results show that the proposed method responds very well, being insensitive to fault type, fault distance, fault resistance, and fault inception angle. The
proposed scheme solves the problem of aged cables with change of electric parameters. In addition, it gives an accurate estimation of the fault resistance in all fault types.

Alham, M. H., M. F. Gad, and D. K. Ibrahim, "Potential of Wind Energy and Economic Assessment in Egypt Considering Optimal Hub Height by Equilibrium Optimizer", Ain Shams Engineering Journal, vol. 14, issue 1, pp. Article no.101816, 2023. Abstract

In Egypt, the wind market increases quickly to make it one of the top countries in the Middle East. This
study discusses the viability of wind resources and the economic assessment for four locations in Egypt:
Ras El-Hekma, Farafra, Nuweiba, and Aswan through two stages. In the first stage, the optimal hub height
for some wind turbines has been calculated by using Equilibrium Optimizer (EO) algorithm to achieve
maximum wind energy with overall minimum cost. The second stage, the economic assessment has been
evaluated by using such turbines to calculate the cost of energy (COE) compared to the global and
Egyptian production costs of wind energy. Developed MATLAB programs are applied for statistical analysis
of wind data. The results have shown that Ras El-Hekma’s average wind speed is higher than other
sites and its wind energy potential is the best. Moreover, the economic assessment for selected locations
turns out that Ras El-Hekma by using EWT-DW61/22 turbine has the lowest COE.

Younis, R. A., D. K. Ibrahim, E. M.Aboul-Zahab, and A. ’fotouh El'Gharably, "Power Management Regulation Control Integrated with Demand Side Management for Stand-alone Hybrid Microgrid Considering Battery Degradation", International Journal of Renewable Energy Research, vol. 9, issue 4, pp. 1912-1923, 2019. AbstractWebsite

A new Power Management Regulation Control (PMRC) integrated with Demand Side Management (DSM) strategies is proposed to enhance the Energy Management System (EMS) of a stand-alone hybrid microgrid. The microgrid combines Wind and PV systems as Renewable Energy Sources (RES) with a hybrid Energy Storage System (ESS) of Battery and Fuel Cell/Electrolyzer set. Towards achieving Net Zero Energy Supply, such microgrid is adequate in remote and isolated new communities with AC controllable critical and noncritical loads. The proposed PMRC implies two-levels of control based on Multi-Agent System (MAS). The first level keeps the output power of each source in its maximum available output power by applying maximum power point tracking (MPPT) techniques. The second level is based on making proper decisions for achieving the power balancing regulation and coordination between the available and the reserve power of the RES and ESS under different operating modes. Valley Filling, Energy Conservation and Load Shifting are applied as DSM strategies to improve loads sustainability during system contingencies. Considering the battery as the most expensive part in the microgrid, the effectiveness of the proposed strategy is further verified by determining the maximum permissible estimated battery lifetime during the operation in all possible scenarios. Extensive simulation studies for various scenarios of microgrid operation in a year were carried out using Matlab/ Simulink with realistic typical wind speed, solar irradiation data and restricted by the status of available ESS.

Dawoud, M. A., D. K. Ibrahim, M. I. gilany, and A. ’F. El’Gharably, "Proposed Application for Rate of Change of Phasor Voltage in Fault Detection and Coordination Studies in MV Distribution Networks", Iranian Journal of Science and Technology, Transactions of Electrical Engineering, vol. 45, issue 3, pp. 815–831, 2021. Abstract

Selectivity, reliability and security of electrical distribution systems are important issues in modern power systems. The protection coordination approach that depends on fault current only is no longer valid for medium voltage (MV) distribution systems; it has major limitations because of varying network conditions. In this paper, a new protective coordination technique is proposed in MV distribution networks. The proposed technique is based on calculating the rate of change of phasor voltage (ROCOV) in each feeder to discriminate and locate the faulty section. The measured ROCOV values and the required relay operating time take the shape of the standard inverse-time characteristics that are used for overcurrent relay. The system allows full coordination between the primary and backup relays. Without any need for communications, the proposed technique proved good robustness during different transient healthy conditions. The setting of the proposed relay does not need to be re-adjusted with the changes in network operating conditions since it depends on system voltage not the loading current. The proposed technique is tested using extensive MATLAB simulations under different faulty and healthy conditions in a MV distribution system. The results indicate that the proposed technique meets the fundamental protective requirements such as selectivity, reliability, sensitivity, and speed as well.

Mohamed, S. H., Z. H. H., I. D. Khalil, and A. E. L. - Z. E. EL-Din, "A Proposed Coordination Strategy for Meshed Distribution Systems with DG Considering User-defined Characteristics of Directional Inverse Time Overcurrent Relays", International Journal of Electrical Power & Energy systems, Elsevier, vol. 65: Elsevier, pp. 49-58, 2015. AbstractWebsite

In this paper, coordination strategy that considers using user defined characteristics for the inverse time overcurrent relays is proposed. Typically, the coordination between relays operating times within meshed systems are achieved by adjusting two relay settings; pick up current and time multiplier setting (TDS and Ip). The equation that models the digital inverse time overcurrent relay operation has two constants; one of them represents the constant for relay characteristics (A) and the other one represents the inverse time type (B). The proposed coordination strategy considers the two relay characteristics constants as continuous variable settings that can be adjusted. These (A and B) values are chosen optimally in addition to (TDS and Ip) to achieve coordination. The coordination problem is formulated as a nonlinear programming problem where the main objective is to minimize the overall time of operation of relays during primary and backup operation considering faults at different locations. The results are compared against the relay coordination using the conventional settings. The problem is applied to the meshed power distribution network of the IEEE 30 bus systems equipped with synchronous based DGs. The results show that the proposed strategy can significantly reduce the overall relay operating time and thus making it an attractive option for meshed distribution systems with DG.

Dawoud, M. A., D. K. Ibrahim, M. I. gilany, and A. F. Abdel-Rheem, "A Proposed Passive Islanding Detection Approach for Improving Protection Systems", International Journal of Renewable Energy Research, vol. 10, issue 4, pp. 1940-1950, 2020. Abstract

Integration of Distributed Generation (DG) on the power system networks causes several difficulties, especially for the system protection. One of the important problems associated with system protection is the islanding that takes place when a DG unit (or group of units) continues to energize a part of the load separated from the main utility. As a result, many obstacles occur such as voltage and frequency fluctuation, in addition to personnel safety problems during maintenance. In this paper, the islanding problem is discussed and also the previous islanding detection techniques are investigated to get an efficient technique for islanding detection. The proposed technique is based on estimating the Rate of Change of Zero Sequence of Second Harmonic Voltage at the Point of Common Coupling (PCC). The proposed technique is extensively tested for inverter-based DG includes wind turbines with double-fed induction generator (DFIG). The proposed technique could distinguish the islanding operation correctly within only one cycle without non-detection zone (NDZ). In addition, it could differentiate between the islanding operation at different values for active and reactive power mismatch. Several scenarios are tested such as normal load variation, capacitor switching and power quality disturbances like voltage sags and swells. Faults and outage of one of DGs are also tested.

Mokhtar, N. M., H. Mohamed Sharaf, D. K. Ibrahim, and A. ’F. El’Gharably, "Proposed Ranked Strategy for Technical and Economical Enhancement of EVs Charging with High Penetration Level", IEEE Access, vol. 10, pp. 44738-44755, 2022. Abstract

Car exhaust is one of the most common causes of ozone hole aggravation, electrical vehicles (EVs) represent a promising solution to avoid this problem. Despite the benefits of EVs, their random charging behavior causes some difficulties regarding the electric network performance, such as increased energy losses and voltage deviations. This paper aims to achieve the proper scheduling of the EVs charging process, avoid its negative impacts on the network, and satisfy the EVs users’ requirements. The EVs charging process is formulated as an optimization problem and solved using particle swarm optimization. The optimization problem formulation considers the EV arrival and departure times and the state of charge required by the user. Different strategies such as separated, accumulated, and ranked strategies with continuous or interrupted fixed charging have been applied to solve the uncoordinated EVs charging problem. These strategies are extensively tested on the modified IEEE 31 bus system (499-node network), using the combination of both Open DSS and MATLAB m-files. The simulation results confirm the effectiveness of the proposed accumulated ranked strategy with interrupted fixed charging in improving the overall power system performance. The achieved improvements include minimizing: the peak power consumed, the peak power losses, and the voltage drop. Moreover, the cost of the EVs charging in most of the feeders has been decreased to a satisfying value. A comparison between the proposed strategy and some previously reported strategies has been performed to ensure the technical and economic enhancement of the proposed strategy.

Ibrahim, D. K., E. S. T. E. Din, E. M. Aboul-Zahab, and S. M. Saleh, "Real time evaluation of DWT-based high impedance fault detection in EHV transmission", Electric Power Systems Research, vol. 80, issue 8: Elsevier, pp. 907-914, 2010. AbstractWebsite

It is possible to capture the required travelling wave information contained in fault transients using wavelet transform. This paper presents practical real time testing for the high impedance fault (HIF) detection algorithm based on real time accidents data. The proposed scheme is implemented for HIF detection in extra high voltage transmission lines. The classifier is based on an algorithm that uses recursive method to sum the absolute values of the high frequency signal generated over one cycle and shifting one sample. Characteristics of this scheme are analyzed by extensive real time studies that clearly reveal that this technique can accurately detect HIFs in the EHV transmission lines within only half a cycle from the instant of fault occurrence. The reliability of this scheme is not affected by different fault conditions such as fault distance and fault inception angle.

Shafei, M. A. R., M. S. Mohamed, A. A. Mansour, and D. K. Ibrahim, "Recharging Portable Devices by Photovoltaic Modules Using Inductive Power Transfer", International Journal on Energy Conversion (IRECON), vol. 9, issue 5, pp. 230-238, 2021. Abstract

Portable devices are part of people’s daily lives, since they provide the capabilities that make life easier. However, they consume much energy that requires continuous charging. Integrating renewable energy sources, especially photovoltaic (PV) modules into wireless charging, has been widely adopted in order to increase availability, flexibility, safety, and robustness. In this paper, a new variable frequency control technique for inductive power transfer (IPT) is proposed in order to overcome the switching frequency limitation and increase the transfer efficiency without increasing the switching frequency. At first, charging power (PV power) is stored in a battery. Then, it is transferred based on inductive coupling when needed. The hardware of the proposed wireless charging system has been carried out for two different configurations. The first one is the single switch using a variable frequency control algorithm, which has achieved 40% efficiency. The other one uses half-wave inverter applying no resonance for two types of core: Nano-crystalline and ferrite. For that configuration, the maximum achieved efficiency has been 80% at zero air gap and 36.91% at the 5 mm air gap by the Nano-crystalline core.

Elhabashy, M. M., H. M. Sharaf, and D. K. Ibrahim, "Reliable protection for static synchronous series compensated double-circuit transmission lines based on positive sequence active power calculations using PMUs", Electric Power Systems Research, vol. 223, issue October 2023, pp. Article no.109695, 2023. AbstractWebsite

Static Synchronous Series Compensator (SSSC) allows dynamic control capabilities of transmitted power. Unfortunately, inserting SSSC in transmission lines (TLs) disturbs impedance-based distance relays as their directionality and reachability are affected by overreaching or underreaching. This paper proposes an approach for protecting double-circuit TLs compensated with SSSC. It relies on the centralized wide-area protection architecture to calculate a proposed driven index: the rate of change of positive sequence active power difference. Phasor measurement units (PMUs) at TL ends estimate voltage and current phasors to calculate the positive sequence active power at TL ends and send them to the system protection center that evaluates the index and gives the trip decision or not. Ensuring the sensitivity, dependability, and security of the approach is essential. So, the overall scheme integrates two other algorithms. One is based on the polarities of the incremental power at both ends to determine whether the fault is internal or external. The other evaluates the phase angle of the integrated impedance to deactivate the power swing-blocking function for fault detection. The scheme's effectiveness is validated comprehensively through extensive simulation tests for fault and system conditions. The results show that the proposed approach is fast, secure, selective, and reliable.

Dawoud, M. A., D. K. Ibrahim, M. I. gilany, and A. ’F. El’Gharably, "Robust Coordination Scheme for Microgrids Protection Based on the Rate of Change of Voltage", IEEE Access, vol. 9, pp. 156283-156296, 2021. Abstract

The wide application of microgrid concept leads to challenges for the traditional protection
of distribution networks because of the changes in short circuit level and network topology during the two
modes of microgrid operation. This paper proposes a promising solution for these problems by offering
a new protection coordination scheme not affected by the variation of short circuit level or the changes
in network topology. The proposed protection scheme is based on local measurements at relay location
with low sampling frequency by computing the rate of change of fundamental voltage (ROCOV) to detect
different fault types, identify the faulty zone accurately and guarantee robust coordination between primary
and backup relays. The proposed coordination scheme can be achieved by optimizing either two settings for
relay characteristic (time dial setting and pickup value) or four settings (time dial setting, pickup and the
parameters that control the characteristic shape (A & B)). The proposed scheme is extensively tested using
MATLAB simulations on the modied IEEE 14 bus meshed network embedded with synchronous/inverter-
based distributed generation units under wide variations in operating conditions and short circuit levels
for both grid-connected and islanded modes of operation. The achieved results conrm that the proposed
coordination scheme can maintain the coordination between primary and backup relays for different fault
locations, types and different topologies. It provides selective, reliable, and secured microgrid operation
compared with conventional schemes, using fault current limiters and some other techniques discussed in
the literature.

Hamdy, M., M. Elshahed, D. Khalil, and E. E. - D. A. El-Zahab, "Stochastic Unit Commitment Incorporating Demand Side Management and Optimal Storage Capacity", Iranian Journal of Science and Technology, Transactions of Electrical Engineering, vol. 43, issue 1, pp. 559–571, 2019. AbstractWebsite

High penetration of wind energy imposes several operational challenges due to its uncertainty and intermittent nature. Flexible energy resources represent key solutions to compensate for power mismatch associated with wind power (WP) uncertainty and intermittency. This paper proposes a new stochastic unit commitment (SUC) problem formulation including high penetration of wind energy, energy storage system (ESS), and demand side management. Firstly, the Latin hypercube sampling is combined with Cholesky decomposition method to generate different WP scenarios. The simulated scenarios are then reduced using the fast forward selection algorithm. Finally, a novel SUC formulation implements these reduced scenarios to size the ESS optimally, considering its cost and benefit maximization of wind energy. To validate the proposed approach, a nine-unit test system is used to demonstrate the reduction in the operational cost and the increase in the utilized wind energy under different operational conditions.

Younis, R. A., D. K. Ibrahim, E. M.Aboul-Zahab, and A. ’fotouh El'Gharably, "Techno-economic investigation using several metaheuristic algorithms for optimal sizing of stand-alone microgrid incorporating hybrid renewable energy sources and hybrid energy storage system", International Journal on Energy Conversion (I.R.E.CON.), vol. 8, issue 4, pp. 141- 152, 2020. Abstract

Increasing energy demand worldwide has resulted in more penetration of renewable sources for developing non-polluted electric energy despite their prices are not economically competitive to traditional generation systems due to intermittent nature of renewable resources. Energy storage systems are used to counteract the intermittent nature of renewable sources. Therefore, the optimal sizing and design of stand-alone renewable generating systems is a significant concern to get a more cost-effective system. This paper focuses on achieving the optimum design and size of a microgrid to meet the load requirements and reducing the total cost including capital, investment, operational and maintenance costs. For this aim, the sizing problem is formulated to be solved using three well-known metaheuristic algorithms, namely, Particle Swarm Optimization (PSO), Grey Wolf Optimization (GWO) and Cuckoo Search Optimization (CSO). The employed microgrid comprises hybrid renewable energy sources of PV/Wind systems integrated with a hybrid energy storage system of Battery and FC/Electrolyzer set for supplying AC loads located in Zafarana, Egypt. On the basis of real meteorological data of the studied location, the produced energies from the renewable sources are estimated using MATLAB developed algorithms. The simulation results showed that the optimized design using CSO can robustly and efficiently yield the optimal design of a microgrid.

Shazly, J. H., M. A. Mostafa, D. K. Ibrahim, and E. A. E. E. Zahab, "Thermal Analysis of HV Cables with Several Types of Insulation for Different Configurations in The Presence of Harmonics", IET Generation, Transmission & Distribution, vol. 11, issue 14, pp. 3439 –3448, 2017. AbstractWebsite

In this contribution, the three-phase underground cable is modelled using COMSOL Multiphysics software to evaluate the steady state and transient thermal performances. Finite element technique is applied using the heat conduction equation to study the temperature distributions in power cables components and the surrounding environment for both linear and non-linear loads. A real case study of 220 kV, 340 MVA three phase single core copper cables insulated by XLPE is studied. Other types of insulation such as oil, and SF6 gas and their contributions of convection and radiation are investigated at trefoil and flat configurations. The loading capability under different ambient conditions for average moisture soil and dry soil with low moisture content are also evaluated taking into account the unfavourable effect of dry zones formation. Moreover, the challenge of predicting the accurate thermal performance and estimating the required derating factor in the presence of odd harmonics is considered. The effect of the change of the frequency spectrum of the non-linear load current by involving different simultaneous harmonic orders for the same total harmonic distortion is extensively investigated for both flat and trefoil configurations. It is concluded that all harmonics contributions should be considered, to accurately calculate the required cable derating.

Abdel Aziz, M. M., A. F. Zobaa, D. K. Ibrahim, and M. M. Awad, "Transmission lines differential protection based on the energy conservation law", Electric Power Systems Research, vol. 78, issue 11: Elsevier, pp. 1865-1872, 2008. AbstractWebsite

This paper proposes a differential protection scheme for transmission lines using the energy conservation law. The real power signals at both ends (sending and receiving) of the line are compared with a prespecified value, if the resultant is more than this value, an internal fault is indicated in the transmission line zone. The proposed technique is evaluated using PSCAD/EMTDC program configurated to model the effect of faults on typical 500 kV transmission line. Extensive simulation studies show that this protection scheme has the ability to discriminate internal faults fast and accurately, and is more reliable than conventional biased differential protection scheme, and suitable for all types of lines. Details of the proposed relay design are given in the paper; also results of some performance studies are given.

Gilany, M. I., E. M. T. Eldin, M. M. Abdel Aziz, and D. K. Ibrahim, "Traveling wave-based fault location scheme for aged underground cable combined with overhead line", International Journal of Emerging Electric Power Systems, vol. 2, pp. 1032, 2005. AbstractWebsite

This paper presents a novel wavelet-based travelling wave fault location algorithm for aged underground cables in transmission systems. Such transmission systems consist of overhead lines combined with underground power cables. Applying the singularity detection feature of wavelets as a powerful signal processing tool, the first and second initial arrival of the voltage travelling waves at the first end of the overhead as well as at the terminal end of the aged cable line can be identified reliably without the need for detection the sign of these waves. In this paper modal signals, rather than the phase signals, are
the inputs to the relay. The proposed algorithm is capable of eliminating the effect of the change in the propagation velocity of the travelling waves over the age of the cable. It can be used on-line
following the operation of digital relays or off-line using the data stored in the digital transient recording apparatus. Extensive simulation studies carried out using ATP/EMTP show that the proposed algorithm provides an accepted degree of accuracy in fault location under different fault conditions.

Gilany, M., D. K. Ibrahim, and E. S. T. E. Din, "Traveling-wave-based fault-location scheme for multiend-aged underground cable system", Power Delivery, IEEE Transactions on, vol. 22, issue 1, pp. 82-89, 2007. Abstract

This paper presents a novel wavelet-based fault-location scheme for aged cable systems when synchronized digital fault recorded data are available at the two terminals of each cable. The proposed scheme estimates the fault location in multiend-aged cable systems using the theory of wavelet singularity detection as a powerful signal processing tool. The arrival of the first and second voltage traveling waves at both ends of the power cables can be identified reliably. The developed wavelet processing scheme is applied on the modal coordinates instead of the phase coordinates. The proposed scheme has the ability to eliminate the impact of the change in the propagation velocity of the traveling waves on the fault-location calculations. This will help solve the problem of cable changing parameters, especially the change of the relative permittivity of the cable with age. The method is valid even with faults that are very close to busbars. Characteristics of the proposed fault-location scheme are analyzed by extensive simulation studies using Alternative Transients Program/Electromagnetic Transients Program. The results indicate an accepted degree of accuracy for the suggested fault locator.

Gilany, M., E. S. T. El Din, and D. K. Ibrahim, "Travelling Wave-based Fault Location Scheme for Multi-End Aged Underground Cable System", International Journal of Power and Energy Systems, vol. 28, issue 2: IASTED ANAHEIM, pp. 160, 2008. AbstractWebsite

Abstract—This paper presents a novel wavelet-based fault-location scheme for aged cable systems when synchronized digital fault recorded data are available at the two terminals of each cable. The proposed scheme estimates the fault location in multiend-aged cable systems using the theory of wavelet singularity detection as a powerful signal processing tool. The arrival of the first and second voltage traveling waves at both ends of the power cables can be identified reliably. The developed wavelet processing scheme is applied on the modal coordinates instead of the phase coordinates. The proposed scheme has the ability to eliminate the impact of the change in the propagation velocity of the traveling waves on the fault-location calculations. This will help solve the problem of cable changing parameters, especially the change of the relative permittivity of the cable with age. The method is valid even with faults that are very close to busbars. Characteristics of the proposed fault-location scheme are analyzed by extensive simulation studies using Alternative Transients Program/Electromagnetic Transients Program. The results indicate an accepted degree of accuracy for the suggested fault locator.

Tourism