Zakariya Rajab

The benefits of the transition from fossil fuel to solar energy in Libya: A street lighting system case study

The Libyan economy is dominated by the oil and the gas industry which are considered as the primary energy sources for the generating power plants. With the increased energy demands in the near future, Libya will be forced to burn more oil and gas. This, in turn will result in reducing the country revenue, threatening the economy and increasing the CO2 emission. This triggers the alarm for Libya to an urgent plan to diversify the energy sources through using sustainable energy. The sun showers Libya every day by a huge amount of sunshine, especially during the peaks in the summer days. Recently, the country has been struggling to satisfy its escalating energy demands. The residential and street lighting loads constitute more than 50% of the electricity demands in Libya. Street lighting consumes more than 3.996 TW h, which is around one fifth of the energy demands in Libya. Energy conservation and transition from fossil fuel to renewable energy could have significant profit on the energy sector in Libya. For example, Libya is still relying on the old-fashioned, inefficient and unsustainable street lighting systems. Replacing the old technology lighting systems with up-to-date solar powered lighting system can achieve energy saving and sustainability. In this paper, improving the energy situation in Libya through replacing the high pressure sodium street lighting systems with solar powered LED street lighting systems is investigated. A four km road is chosen as a case study. Four alternatives are analyzed; grid-powered high pressure sodium lamp street lighting system, grid-powered LED lamp street lighting system, stand-alone solar powered LED street lighting system and grid-connected solar powered LED street lighting system. The four options are compared in terms of the capital cost, maintenance cost, total cost, fuel cost and the CO2 emission. Replacing the high pressure sodium lamp system with LED lamp system saves 75% of energy and reduces the CO2 emission by 75%. The stand-alone solar powered LED lighting system cuts the CO2 emission, saves the fuel and is economically feasible. Furthermore, improvement is attained if the solar powered lighting system is connected to the grid where the excess energy is fed to the grid. The two solar powered options are economically feasible and sustainable.

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.

Evaluating the value of the excitation capacitance of a wind turbine/induction generator system using genetic algorithms

Due to their robustness, low cost, and low maintenance, induction generators are good candidates for wind energy systems. In addition, when the wind turbine is isolated from the grid, the induction generator can operate within a wide speed range which utilize maximum power extraction. To ensure that voltage buildup will take place between the machine terminals, the reactive power required by the machine must be supplied. To achieve that, a three phase capacitor bank is connected to the generator terminals. Evaluating the adequate value of the capacitance is very crucial since it affects the value of the generated voltage. In this paper, the desired operating voltage and the corresponding value of the magnetizing inductance are defined from the magnetizing curve. By using genetic algorithms (GAs), the corresponding values of the excitation capacitance and the rotor slip are evaluated. Matlab/Simulink model is then used for validation. It is noticed that there is a good agreement between the values predicted by the GAs and the ones obtained from the simulation.

Load frequency control system with smart meter and controllable loads

The advances in the network technology and the emergence of the renewable energy as primary sources have changed the current view of the power system control. Smart meters will become a very important component in future power systems. In the event of an emergency the demand will play vital role in the stability of the power system. Conventionally, when a sudden generation loss occurs the generators have the responsibility to restore the system frequency. This process is expensive, comparably lengthy and increases the CO2 emissions. The smart meters can control the loads and hence secure the system stability, faster than the conventional generators. One of the important issues is to understand the operation of these emerging devices. In this paper, we present a Matlab/Simulink model for load frequency control system with demand-side control through the smart meter. From the simulation the demand-side control can improve the performance of the load frequency control system.

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.

Techno-economic feasibility study of Solar Water Heating system in Libya

Most of the generated electricity in Libya is produced from fossil fuel. As the energy demand will escalate dramatically in the near future, more oil and gas are consumed and hence more CO2 emissions. Therefore for a sustained development, the renewable energy must share in the electricity market. Because of the location of Libya in the highest sunny belt, the solar energy is capable of providing some or all the energy required. The residential loads constitute around thirty percent of the total load demands and the electrical water heaters forms 10% of the total energy consumption. As the country is struggling to satisfy its energy demands the domestic solar water heaters can play a great role in reducing the energy consumption. In this paper, a proposal for replacing the conventional water heaters with the domestic solar water heaters (DSWH). The technical and economic feasibility of DSWHs are investigated using RETScreen software. The conventional electrical water heater and the solar water heater are compared in terms of electricity saving, capital cost, maintenance cost, and CO2 emissions. A case study for 5000 houses in Benghazi has been selected. Over 20 years the cost of the solar water heaters is 49,875,000 LD while the cost of the conventional electrical water heaters is 214,050,000 LD which is four times higher. The results from the paper show that the DSWH is economical feasible in Libya and can result in fuel saving and CO2 emission reduction.

Economic feasibility of solar powered street lighting system in Libya

Libya is one of the countries blessed with high potential of renewable energy. Currently, the electricity in Libya is produced from fossil fuel to meet the demand on the local electricity market. In the near future, the demand on the energy will increase significantly. The growth in energy demand will lead to more oil and gas consumption in Libya. Additionally, the CO2 emissions will increase substantially. Therefore, Libya should make an urgent plan to use its alternative energy supplies to cover some of its load requirements. For example street lighting forms around 20% of the electricity consumption. The street lighting system in Libya is based on the high pressure sodium lamps which are powered from the electricity grid. The lamp rating ranges from 250 to 400 watts. As the country struggles to satisfy its electricity demands we propose replacing the conventional street lighting system with solar powered LED (Light emitting Diode) lighting system. The paper presents a case study for 4 km solar street lighting system in Almarj city. Two proposals are investigated, the conventional lighting system and the solar powered LED lighting system. A feasibility study of the street lighting system is carried out. The cost, energy savings and the CO2 emission of the two proposed systems are compared. The cost of the solar powered LED street lighting system is 1,250,200 LD, while the cost of the high pressure Sodium lamp street lighting system is 2,117,255 LD. Additionally, the solar powered LED street lighting system has no CO2 emissions.

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.