Faisal A. Mohamed

Wind energy conversion systems: Classifications and trends in application

In recent years, wind turbines have become an acceptable alternative for electrical energy generation by fossil or nuclear power plants, because of the environmental and economic benefits. Wind energy conversion systems are becoming a reliable competitor of classical power generation systems, which are facing to constantly changing operating parameters, such as fuel cost, multiple fuel tradeoffs. This study is based on exhaustive review of the state of art in order to comparison the performances of electrical generators. The different wind energy conversion systems are compared based on topology, cost, efficiency, power consumption and control complexity. In addition, a Matlab/Simulink simulation, for wind energy induction generator in isolated network, will be exposed.

Modeling approach to evaluate wind turbine performance: Case study for a single wind turbine of 1.65 MW in Dernah Libya

Various techniques can be used to investigate the performance of mechanical-to-electrical energy conversion. These techniques vary from one to another, owing to their characteristics, complexity, performance, cost, etc. Besides, they are suitable for a wide range of energy sources and applications from very low to very high power levels. In this paper a mathematical model for a 1.65MW Squirrel Cage Induction Generator (SCIG) wind turbine installed in Derna, Libya is tested in Matlab/Simulink and was validated using Alternative Transient Program-Electromagnetic Transient Program ATP-EMTP software through which its dynamic behavior can be accurately predicted. Power coefficient, active power, reactive power, and electromagnetic torque under two proposals are investigated, variable speed and fixed speed. It is noticed that there is a good agreement between the values predicted by the ATP-EMTP and the ones obtained from the Matlab/Simulink simulation. The model is useful for analyzing the behavior and performance of wind turbine in medium voltage power network.

Minimizing the impact of distributed generation of a weak distribution network with an artificial intelligence technique

Integration of renewable energy sources directly into the distribution network become a common practice nowadays, the contribution of renewable energy sources to the distribution network predominate by weather conditions which change short circuit level capability for the electric network. This change in the network configuration could influence the operation of the protective devices in the distribution network. In this study, an online adaptive protection scheme base on adaptive fuzzy algorithm proposed to update and optimize the protection coordination when network topology has been changed. The online algorithm depends on different parameters such as the status of main feeder circuit breaker and the prefault power flow in the network. The simplified network represents a portion of the Eastern Libyan Electric Network implemented in ETAP package.

Mitigating the impact of Distributed Generator on medium Distribution Network by adaptive protection scheme

Nowadays integration of Distributed Generation (DG) into the Distribution Network (DN) become a common practice for its advantages over the conventional sources in the environmental and economical influence. Despite DGs benefits, up growth in DG numbers and the diversity in the technology used, arise problems including power quality, voltage profile, network stability, and protection coordination, which lead to a change in the network configuration and topology to mitigate the effects emerging from penetrating DG in the network. In this study the impact of DG on the protection setup of an Existing Distribution network has been investigated, the main protection problems consist of protection blinding, false tripping, and unintentional islanding. The approach presented in this study uses the adaptive scheme to alter the protection system coordination according to the change in the network configuration. The simplified system simulated with Electric Transient Analyzer program (ETAP) and ATP/EMTP software. Validation of the results in different scenarios has been studied to evaluate the efficiency of the proposed adaptive scheme, also suggestions to integrate DG in the DN are presented.

Applying adaptive protection scheme to mitigate the impact of distributed generator on existing distribution network

Many studies indicate the importance of distributed generation (DG) as one of the best alternatives to conventional energy sources. The growth in population is causing a significant increase in electricity demand all over the world, which creating a considerable need for further investment in the electric network infrastructure. However, integration of new renewable energy source in the distribution network (DN) could impact the stability and the reliability of the distribution network if successful integration of renewable and distributed generation into the distribution network not achieved. Successful integration of distributed energy resources requires optimized control and planning for the network configuration which relies basically on the decentralized energy source management and protection system coordination. The aim of this study is to investigate the impact of utilizing DG on the performance of DN, especially on the over-current protective devices. Also, introducing a proposed adaptive protection scheme to mitigate the influence of DG penetration on the protection coordination by adding group setting, which exists in nowadays numerical protective relays, for different operating conditions such as islanding mode, and full MVA capacity of a DG. The simplified power system simulated in NEPLAN and ETAP packages represents Benghazi medium voltage distribution network. The simulation and results show the effectiveness of the proposed approach on the reliability and stability of the distribution network.

Genetic algorithm–based calculation of the excitation capacitance of a self-excited induction generator for stable voltage operation over load and speed variations

In order to provide the reactive power demand of a self-excited induction generator which is required to achieve a voltage build-up, a three-phase capacitor bank is connected between the generator terminals. As loading increases, the operating point on the magnetizing curve moves toward the linear region which may lead to the collapse of the generated voltage. In this article, genetic algorithms are used to evaluate the value of the excitation capacitance that makes the machine operate in the saturation region which ensures a stable generated voltage. To verify the effectiveness of this method, a laboratory machine which has a relatively high stator and rotor resistances and leakage reactance is considered. The values of the excitation capacitances predicted by the genetic algorithms are applied to the machine Simulink-based model. The results obtained by the simulation are compared with experimental results which show a good agreement.

An intelligent protection scheme to mitigate the impact of integrating large share wind energy resources in a weak distribution network

Although integration of wind distributed generation directly into the distribution level has considerable advantages, increased penetration of wind distributed generation (renewable distributed generation) alters the network configuration and jeopardizes the protection system operation and system stability; for this reason, necessary changes in power system protection philosophy must be achieved. Modern numerical relays offer extraordinary features and fast and accurate methods for spotting and detecting different unbalanced operating conditions and can be used to mitigate the influence of integrating wind distributed generation into distribution network. In this study, an adaptive directional negative protective scheme was implemented in the medium-level distribution network to investigate and evaluate the performance of protection system and introduce new adaptive protective scheme based on negative overcurrent protection to increase the selectivity and sensitivity of the protection system in case of unbalanced faulty conditions. The medium-level distribution network of Libya Eastern electric network had been implemented in ETAP software to address and evaluate the efficiency of the proposed approach.

Modeling and simulation for powertrain design and control of unconventional vehicles

The aim of this paper is to propose a methodology of modeling and simulation of electrical vehicles (EV) for design and control of their powertrain. On the base of this method, new software tool which is called ELEctric VEhicle Simulator (ELEVES) has been developed in Delphi environment with a Pascal code. It provides the vehicle engineering community with an easy-to-use, flexible, yet robust and supported analysis package for electric vehicles modeling. It uses the Component Hybrid Dynamic Nets (CHDN) to graphically present and extract the equations of studied system. CHDN allow every component of electric vehicle architecture to be individually modeled and then represented in software library. Finally, an example of application is treated in order to highlight ELEVESs ability to design and control electrical components of EV. This study concerns the two in-wheel drives EV with speed control of vehicle. The obtained results have been compared with those of Matlab/Simulink in order to validate our software.