Doaa Khalil Ibrahim

This paper introduces a protection scheme for interconnected networks based on proposed Directional Overcurrent Relays (DOCRs) with user-defined two-level characteristics. By getting usage of the capabilities available in modern digital DOCRs, the proposed relay will have two user-defined characteristics; one for its primary operation and another for its backup operation (two-level characteristics) to fit a specific application or system. The coordination between the proposed relays is formulated and solved as a non-linear optimization problem to minimize their operating time and reduce the thermal impact caused by short circuit currents through electrical equipment while maintaining the technical constraints.
Extensive comparative studies have been performed to ensure the effectiveness of the proposed protection
scheme. Firstly, the performance of the traditional one-level characteristic relay (COLC) with two settings is
compared to the conventional two-level characteristic relay (CTLC) with three settings. Then a further investigation is carried out by suggesting increasing the number of settings to seven, named as the user-defined two-level characteristic relay (UDTLC), and then to nine settings, named as the shifted-user-defined two-level characteristic relay (SUDTLC). Finally, different multi-objective functions with proper weighting factors are investigated to determine the most effective one with the best performance for the proposed idea.
The distribution portion of the IEEE 30-bus system has been used to test and verify the proposed characteristics extensively. The optimal coordination problem is solved using the fmincon function in MATLAB. Based on the achieved results, the proposed characteristics of UDTLC and SUDTLC guaranteed a considerable reduction in operating times. In addition, the achieved results deduced that using a different multi-objective formulation has little impact on reducing operating time due to using the proposed characteristics UDTLC and SUDTLC, which means solving the coordination problem is mainly dependent on the applied characteristics.

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.

With increasing global great concern over greenhouse gas emissions and their harmful effects on environment, huge number of wind turbines are recently connected to electrical grids. Nowadays, Egypt has continuous development of wind energy projects; it makes a great effort at Gulf of Suez area especially in Al Zafarana district. This paper focuses on studying the dynamic performance of the 5th phase of Al-Zafarana wind farm, which is made of 100 Gamesa G52/ 850kW Doubly Fed Induction Generator (DFIG) machines, using Digsilent /PowerFactory simulation tool as an advanced simulation package. As DFIG is currently one of the most common types employed for Wind Energy Conversion System (WECS), the paper also implements a dynamic model for 850 kW DFIG machine based WECS in Matlab / Simulink environment. A dual reference frame control strategy is applied here to improve the dynamic system performance during balanced and unbalanced grid voltage conditions.

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.

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.

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.

This paper addresses the optimal allocation of Flexible AC Transmission Systems (FACTS) devices in a power system in order to improve voltage stability. With the continuous increase of power demand, FACTS provide a suitable solution by maximizing the usage of existing utilities rather than increasing power generation and building new lines. Due to high cost of such devices their optimal allocation must be ascertained. Particle swarm optimization (PSO) is used in this paper to determine the best location and size of Static VAR Compensator (SVC) where the objective function is to achieve the accepted voltage profile taking into consideration the SVC cost. Simulations are performed on IEEE-14 test system. Results prove the effectiveness of PSO in solving such allocation problem.

The aim of this paper is to determine the possibility of using a stand-alone hybrid energy system to meet the electric load demand of an isolated area using HOMER Software. The combination of using remote area-diesel generators and renewable energy source such as photovoltaic system (PV) with a battery storage can greatly overcome some of diesel generators problems. In this paper, a PV/Diesel generator hybrid energy system is sized to meet the load with about 100 % availability. HOMER is used to optimize the operation of the diesel generator and to calculate the optimum number of the PV modules and batteries that would achieve the minimum initial cost and a desired depth of discharge for battery storage. As the economic issue is greatly concerned, it is necessary to identify the system life cycle cost or the Total Net Present Cost, TNPC, of the optimal hybrid energy system which can also be achieved by HOMER optimization. For observing the economic and technical feasibility of the designed power system and its economics, it is important to assess the effect of uncertainty or the change of several variables such as solar radiation, interest rate and fuel price which can be carried out by performing several sensitivity analyses.