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Aims: To evaluate nutrient status in Koroneiki olive trees grown in sandy soils and calculate the amount of nutrients annually removed by the olive tree. Study Design: Costate Statistical package, in order to calculate means, maximum, minimum, standard deviations (SD), with 12 replicates Place and Duration of Study: El-FIFA farm which is located at km 48 of Cairo-Alexandria road in the north west of Egypt, between January 2011 and December 2012. Methodology: This experiment was carried out on 10 years-old olive trees cv. Koroneki grown on a loamy sand soil. The trees are cultivated at 6 x 6 meters distance (278 tree/ha-1) and grown using standard cultural practices and subjected to moderate pruning every year. Flesh and pit were separated, weighed and dried. Nutrient concentrations in the flesh and pit were determined and used to quantify the nutrients removed by fruit. The materials removed in pruning were separated to branches and leaves, weighed and dried. Based on the dry matter and nutrient concentration in the different tissues, the amounts of nutrients removed annually in pruning were calculated. Nutrient removals were calculated for every organ, by multiplying dry weight by nutrient concentration. These amounts were added together, to obtain the total nutrient removal/tree. Results: Leaves have sufficient contents of N, P, K, Ca, Na, Mn, Zn, Cu and B while the level of both Fe and Mg was high. Nutrients removed annually/tree were: 265.24 g N; 37.93 g P; 353.93 g K; 122.67 g Ca; 76.94 g Mg, 74.78 g Na; 7.288 g Fe; 0.773 g Mn;0.514 g Zn, 0.213 g Cu and 0.663 g B., when the yield was77.33 Kg/tree. Conclusion: It was found under moderate pruning, that fruit and pruned material removed large amounts of nutrients, which can become insufficient for high oil yields in sandy soils. The results obtained are helpful in calculation fertilizer recommendations.

The emerging interest in deployment of plug-in electric vehicles (PEVs) in distribution networks represents a great challenge to both system planners and owners of PEV-parking lots. The owners of PEV-parking lots might be interested in maximizing their profit via installing charging units to supply the PEV demand. However, with stringent rules of network upgrades, installing these charging units would be very challenging. Network constraints could be relaxed via controlling the net demand through integrating distributed generation (DG) and/or storage units. This paper presents an optimization model for determining the optimal mix of solar-based DG and storage units, as well as the optimal charging prices for PEVs. The main objective is to maximize the benefit of the PEV-parking lot's owner without violating system constraints. Two cases are considered in this paper: uncoordinated and coordinated PEV demand. A novel mathematical model is further developed whereby the behavior of vehicles' drivers, in response to different charging prices, is considered in generating the energy consumption of PEVs.

Smart grids have been emerging nowadays as an initiative to operate modern distribution systems in a more economic and efficient way. Energy storage systems (ESSs) are one of the promising technologies that can achieve the goals of smart grids via facilitating the connection of renewable sources, improving system reliability, and controlling the net demand through peak load shaving, etc. In this paper, a comprehensive planning framework is introduced for ascertaining the most cost effective siting and sizing of ESSs that maximize their benefits in distribution networks. A probabilistic approach is further adopted that includes the consideration of the stochastic nature of system components. Such approach allows determining the optimal operation of ESS at each load state. Moreover, contingency planning decisions, in the form of load points to be shed during contingencies, are identified through the approach proposed.

Wind energy has become one of the most cost-effective renewable sources nowadays. However, the stochastic nature associated with wind-energy production represents a great challenge for power-system operations. Therefore, probabilistic techniques are necessary to evaluate the performance of power systems with substantial amounts of wind generation. This paper presents a probabilistic based bi-level optimization approach for evaluating the impact of wind farm location and control strategy on the penetration level of wind farms and electricity market prices. The bi-level optimization model is formulated as mathematical program with equilibrium constraints (MPEC) and solved by means of the NLPEC solver in the General Algebraic Modeling System (GAMS) environment. Several cases studies are presented in this paper to determine to the optimal wind generation penetration and market prices with different locations and control strategies for wind farms. Moreover, some scenarios are discussed in regards to the practical allocation of wind farms.

This article presents a new approach to enhance the capabilities of flywheel energy storage systems to enable increasing the integration of small-scale photovoltaic distributed generation units in distribution systems. The storage capabilities of the flywheel energy storage systems are utilized to suppress the system voltage disturbances caused by the intermittent output power of the photovoltaic distributed generation sources in distribution systems. A dynamic model of the flywheel energy storage systems is presented. The flywheel energy storage systems model is simulated in a practical residential distribution network with small-scale photovoltaic distributed generation sources using PSCAD/EMTDC. The performance of the system is studied before and after installing the flywheel energy storage systems. The simulation results show that utilizing the flywheel energy storage systems technology in distribution systems with installed photovoltaic distributed generation sources can effectively reduce th...

An optimized communication and control infrastructure, based on the microgrid building block concept, for active distribution systems is essential to facilitate powerful control framework under the smart grid paradigm. In this paper, a novel methodology for designing a communication and control infrastructure is presented. The new design takes into account both communication system and distribution system-related aspects. The proposed design facilitates systematic and optimized clustering of the distribution system into a set of virtual microgrids with optimized communication requirements while considering the power quality aspects, characteristics of distributed generation units, distributed energy storage units, and distributed reactive sources. The new design facilitates robust infrastructure for smart distribution systems operation and control, e.g., self-healing control and optimized system-level operation, by using virtual microgrids as building blocks in future distribution systems. The motivations, conceptual design, problem formulation and solution algorithms are presented in this paper. The well-known PG&E 69-bus distribution system is selected as a test case and through several sensitivity studies, the effect of optimization coefficients on the design, and the robustness of the algorithm are investigated. Finally, the algorithm is tested on the IEEE 123-bus distribution system.

The recent deployment of distributed generation has led to a revolution in the use of distribution systems and the emergence of “smart grid” concepts. Smart grids are intended primarily as a means of facilitating the integration of renewable energy sources and of achieving greater system reliability and efficiency. Energy storage systems (ESSs) offer a number of benefits that can help utilities move toward those goals. One of those benefits is the capacity to improve the utilization of network infrastructure by means of proper load management. This paper proposes a methodology for allocating ESSs in distribution systems in order to defer system upgrades, minimize system losses, and take advantage of the arbitrage benefit. The cost and arbitrage benefit of energy storage installation are optimized with respect to system upgrade and energy losses costs. The primary goal of this research is to determine the optimal size and location of storage units to be installed, in addition to their optimal operation, so that total system costs are minimized, while system benefits are maximized. In this paper, a probabilistic load model is adopted instead of utilizing time-series based models, which provide an optimal solution that is valid only for the time-series pattern that is applied.

This paper aims to identify the impact of distributed generation (DG) on the operation of load tap changers used in typical distribution networks. Distribution networks are typically equipped with an under-load or off-load tap changer, referred to as ULTC or OLTC, respectively, to control the voltage of the secondary winding of the substation or regulating transformer. The impact of DG on the operation of OLTC and ULTC is studied in this paper. The work presented is part of an ongoing project that aims to investigate the impact of integrating high penetration levels of DG and establish the maximum penetration limits of DG that can be integrated into typical Canadian distribution networks. For the limited space available, only the Canadian suburban benchmark distribution network is considered in this paper.

The recent deployment of distributed generation has led to a revolution in the use of distribution systems and the emergence of smart-grid concepts. Smart grids are intended primarily as a means of facilitating the integration of renewable energy sources and of achieving greater system reliability and efficiency. Energy storage systems offer a number of benefits that can help utilities move toward those goals. One of those benefits is the capacity to improve system reliability through successful islanding operation. This paper proposes a methodology for the cost-effective improvement of system reliability through the allocation of distributed storage units in distribution systems. The costs of energy storage installation are optimized with respect to reliability value expressed as customers' willingness to pay in order to avoid power interruptions. The primary goal of this research was thus to determine the optimal combination of storage units to be installed and the loads to be shed so that all possible contingencies can be effectively addressed. A probabilistic approach is therefore adopted that includes consideration of the stochastic nature of system components.

Recent deployment of distributed generation has led to a revolution in distribution systems and the emergence of “smart grid” concepts. The smart grid mainly intends to facilitate integration of renewable energy sources and to achieve higher system reliability and efficiency. Different distributed generation types found in modern distribution systems can be classified into two main categories: intermittent- and dispatchable-based distributed generation; the latter has a unique capability of enabling successful islanding operation, thus improving system reliability. This article proposes a methodology for allocating dispatchable distributed generation units in distribution systems to economically improve system reliability. Distributed generation installation and operation costs are to be optimized against the reliability value, expressed as customers’ “willingness to pay” (WTP) to avoid power interruptions. Therefore, the main goal of this research work is to determine the optimal combination betw...

Aims: to evaluate nutrient status in Koroneiki olive trees grown in sandy soils and calculate the amount of nutrients annually removed by the olive tree. Study Design: Costate Statistical package, in order to calculate means, maximum, minimum, standard deviations (SD), with 12 replicates Place and Duration of Study: El-FIFA farm which is located at km 48 of CairoAlexandria road in the north west of Egypt, between January 2011 and December 2012. Methodology: This experiment was carried out on 10 years-old olive trees cv. Koroneki grown on a loamy sand soil. The trees are cultivated at 6 x 6 meters distance (278 tree/ha -1 ) and grown using standard cultural practices and subjected to moderate pruning every year. Flesh and pit were separated, weighed and dried. Nutrient concentrations in the flesh and pit were determined and used to quantify the nutrients removed by fruit. The materials removed in pruning were separated to branches and leaves, weighed and dried. Based on the dry matter and nutrient concentration in the different tissues, the amounts of nutrients removed annually in pruning were calculated. Nutrient removals were calculated for every organ, by multiplying dry weight by nutrient concentration. These amounts were added together, to obtain the total nutrient removal/tree. Results: Leaves have sufficient contents of N, P, K, Ca, Na, Mn, Zn, Cu and B while the level of both Fe and Mg was high. Nutrients removed annually/tree were: 265.24g N

Recently, the concept of microgrids (clusters of distributed generation, energy storage units, and reactive power sources serving a cluster of distributed loads in grid-connected and isolated grid modes) has gained a lot of interest under the smart grid vision. However, there is a strong need to develop systematic procedure for optimal construction of microgrids. This paper presents systematic and optimized approaches for clustering of the distribution system into a set of virtual microgrids with optimized self-adequacy. The probabilistic characteristics of distributed generation (DG) units are also considered by defining two new probabilistic indices representing real and reactive power of the lines. Next, the advantages of installing both distributed energy storage resources (DESRs) and distributed reactive sources (DRSs) are investigated to improve the self-adequacy of the constructed micro-grids. The new strategy facilitates robust infrastructure for smart distribution systems operational control functions, such as self-healing, by using virtual microgrids as building blocks in future distribution systems. The problem formulation and solution algorithms are presented in this paper. The well-known PG&E 69-bus distribution system is selected as a test case and through several sensitivity studies, the effect of the total DESRs or DRSs capacities on the design and the robustness of the algorithm are investigated.

The objective of this paper is to provide an assessment on voltage profiles in residential neighborhoods in the presence of photovoltaic (PV) systems. The network was modeled in PSCAD using common feeder characteristics that Canadian system planners use in suburban residential regions. A simulation study was performed to investigate potential voltage rise issues in the network up to 11.25% total PV penetration in the feeder and LV transformer capacity penetration up to 75%. Results indicate that the PV penetration level should not adversely impact the voltage on the grid when the distributed PV resources do not exceed 2.5 kW per household on average on a typical distribution grid. Moreover, the role of feeder impedance, feeder length, and the transformer short circuit resistance in the determination of the voltage rise is quantified.

Overvoltages in low voltage (LV) feeders with high penetration of photovoltaics (PV) are usually prevented by limiting the feeder's PV capacity to very conservative values, even if the critical periods rarely occur. This paper discusses the use of droop-based active power curtailment techniques for overvoltage prevention in radial LV feeders as a means for increasing the installed PV capacity and energy yield. Two schemes are proposed and tested in a typical 240-V/75-kVA Canadian suburban distribution feeder with 12 houses with roof-top PV systems. In the first scheme, all PV inverters have the same droop coefficients. In the second, the droop coefficients are different so as to share the total active power curtailed among all PV inverters/houses. Simulation results demonstrate the effectiveness of the proposed schemes and that the option of sharing the power curtailment among all customers comes at the cost of an overall higher amount of power curtailed.

This study was carried out in the nursery of the Ornamental Plant Research Department, Horticulture Research Institute, Giza, Egypt during the period from February to November of the two successive seasons of 2009 and 2010. A factorial experiment, in a randomized complete block design (RCBD), with three replicates, was conducted, to investigate the effects of different watering regimes (irrigation with 300, 450 and 600 cm3/pot/week) comprising the main plot and potting media (peat moss, water hyacinth compost, rice hulls compost, date palm leaf compost and a mixture of the four components at equal volume parts) representing the sub-plots on Ficus nitida “Hawaii” plants grown in 25 cm dia. plastic pots. Results show that performance of plants grown in the mixed compost and watered with 450 cm3/pot/week was the best in all characters studied, followed by plants grown in the same medium and watered with either 600 cm3/pot/week (in the second position) or with 300 cm3/pot/week (in the third one). Performance of plants grown in rice hulls compost and watered with 450 cm3/pot/week came in the fourth rank, followed by those grown in peat moss and watered either with 450 or 600 cm3/pot/week, occupying the fifth position in this concern. In contrast, plants grown in date palm leaf compost and watered with 300 cm3/pot/week scored the lowest records in almost all parameters studied, preceded by those grown in the same medium and watered either with 450 or 600 cm3/pot/week.

A study was conducted over 15 years in apple, peach, pear, citrus, grapevine and olive orchards in different locations in Syria. The study aimed at monitoring and evaluating the long-term nutrient behaviour in plants and soil in order to suggest measures for nutrient management improvement. Leaf and soil samples were collected in the years 1982, 1987, 1990 and 1997. The soils were characterized by high pH values, high CaCO 3 and low to medium organic matter contents. Due to the unfavourable soil conditions and ill-chosen fertilizer use, the nutrient balance in the plant tissues was disturbed. To correct the situation, the application of improved nutrient management practices was suggested.

This paper presents a new planning optimization model for distribution substation siting, sizing, and timing. The proposed model involves using linear functions to express the total cost function. The developed model includes different electrical constraints such as voltage drops, substation and transformer capacities, power flow, and radial flow constraints. The proposed planning problem is formulated as a Mixed Integer Linear Programming (MILP) problem to avoid the use of nonlinear programming and thus avoiding the possibility of getting trapped in local solutions. A numerical example is presented to validate the effectiveness of the developed model.

The electrification of vehicles is now considered an effective solution that will reduce fuel consumption and emissions as well as increase energy security through the diversification of available energy sources. The electric energy generated from low-emission renewable resources will play a vital role to meet the electricity needs of the transportation sector and will also address concerns about shifting emissions from the transportation sector to the electricity generation sector. This paper proposes a new approach to evaluate the power system reliability indices incorporating plug-in electric vehicles. The proposed method relies on developing virtual scenarios that cover all possible occurrences for normal demand, conventional generation, renewable resources, and plug-in electric vehicles demand. These scenarios are generated using Monte Carlo Simulation and Marcov Chains

Remote communities mainly rely on diesel for electricity generation. Costs of electricity generation could reach up to 10 times compared to the main electric grid because of the cost of fuel transportation and delivery. With the revolution of smart grid technology, it is possible to quantify the full potential of integrating renewables and smart grid applications to bring real cost savings to these communities. This paper presents details for the Microsoft Excel-based, optimal performance assessment tool for remote grids that has been developed by CanmetENERGY to assess the performance of the electricity grid for remote microgrids and provide a guide for remote microgrid planning.

This paper presents an overview of the minimal complexity level requirement for modeling generic grid-interactive inverter to conduct power flow, protection, stability and power quality studies. For each functional, control or protection block of the inverter system, it describes the appropriate level of complexity needed to perform each of the power system studies. This work serves as a foundation for the development of an inverter modeling toolbox to facilitate power system studies in renewable energy projects. It intends to address the need of utilities to have access to adequate inverter models to perform accurate integration impact studies of photovoltaic or inverter-based wind projects.

This paper investigates the application of dynamic voltage restorer (DVR) versus static compensator (STATCOM) to enhance low voltage ride through (LVRT) capability of wind farms. The research done in the area of LVRT focused on a single machine compensation analysis; however, no such analysis was done for entire wind farms generators. Therefore, the main contribution of this paper is to study LVRT compensation through STATCOM and/or DVR in order to provide guidelines for the implementation of each solution within large wind farms. In this paper, squirrel cage induction generators (SCIGs) are studied using a simplified approach based on torque-speed characteristics of induction machines. The transient stability margin is proposed as indicator of LVRT capability. Analytical calculations are verified against simulation results using PSCAD/EMTDC package.

Hybrid Petri Nets are presented here to model a certain type of production systems called Hybrid systems and to study their behaviour and properties and after that to control these systems. These systems are characterised by having two parts within them the first is a continuous part and the second is a discrete part. By using the Hybrid Petri nets we could use the discrete part to control the continuous part or vice versa. We introduce here a software tool for modelling and simulation of these systems and then to control them. The paper presents an overview of this tool and its working environment and at the end an example is introduced

The I-35 Bridge over the Mississippi River in Minneapolis, Minnesota catastrophically failed during the evening rush hour on August 1, 2007, collapsing into the river. In the years prior to the collapse, several reports cited problems with the bridge structure. This research analytically investigated the cause of the collapse using the Applied Element Method. The bridge was modeled using construction drawings, with relevant structural details and loadings. Structural details included the steel truss, gusset plates, concrete slabs, concrete piers, while structural loading included traffic and construction. AEM provided the cause of collapse of the I35-W Bridge. The cause of collapse was found to be the failure of the gusset plates at connections L11 and U10, which well agreed with the field investigations of the collapsed bridge. The under-designed thickness of the plates, their corrosion, and over loading due to traffic and construction loads at time of collapse were the reasons for the bridge collapse.

This paper proposes a coordinated control method, for static series compensator (SSC) equipped with shunt passive filters, to compensate grid voltage disturbance (sag, swell, voltage interruption and flicker) and load current harmonics. To effectively extract the positive-sequence component of the grid voltage, digital all-pass filters are implemented. These filters can deliver a preferred phase shift and no magnitude drop, unlike conventional low or high-pass filters. According to the extracted positive-sequence component, the angle of the grid phase and the reference voltage for compensation are obtained. This technique can improve the grid voltage stability and mitigate the load current harmonics as well. PSCAD/EMTDC simulations show the usefulness of the proposed technique.

Driven by technical and environmental reasons, it is expected that future increases in electrical demand will be met through the integration of high penetration levels of Distributed Resources (DR) (or distributed generation) into distribution networks. Such integration will introduce new benefits to utilities and their customers; however, it will also bring new challenges to distribution systems planning and operation such as the perturbation of the utility protection system. A working group, including Canadian and US members representing utilities, manufacturers and private consultants, was established to develop protection scheme options for DR interconnection to utility grids. This paper presents the identified best practice protection schemes for both three wire and four wire distribution systems with DRs. One traditional scheme, currently adopted by utilities, and four new proposed schemes are presented.

This paper evaluates the performance of a demand response (DR) system, installed in the remote community of Hartley Bay, British Columbia, which is used to reduce fuel consumption during periods of peak loads and poor fuel efficiency. The DR system, installed to shed load during these periods, is capable of shedding up to 15 per cent of maximum demand by adjusting wireless variable thermostats and load controllers on hot water heaters and ventilation systems in commercial buildings. The system was found to be successful in reducing demand by up to 35 kW during the DR event period, but caused a new, time-shifted “rebound” peak of 30 to 50 per cent following each event. A DR “staggering” method is introduced as a tool for reducing and delaying rebound without affecting occupant comfort and safety. In this work, load prediction models based on linear regression and averaging of historical data were also developed for measuring DR shed and rebound, with models based on averaging found to produce more accurate baselines.

This paper presents and demonstrates a method to quickly identify when regular periodic activities, such as a daily night setback on a thermostat, are inappropriately configured or accidentally reset. Anomalies in periodic building operations are identified by analyzing smart meter electrical demand data in the frequency domain with a weekly travelling time window instead of using time domain functions such as load factor. Initial experiments on a real site found that spectral energy signals for periodic (frequency) hours of 4, 6, 8, 12 and days 1, 3.5 and 7 to be greatly reduced when a device is not functioning appropriately. In addition, the ratio of the DC offset (0 Hz) energy with the other higher periodic energies can normalize the periodic energies to a relative index that can then be used for comparing other seasons and other buildings for periodical performance.

This paper outlines the main accomplishments towards realizing a Smart Microgrid Testbed at the British Columbia Institute of Technology (BCIT), Burnaby, BC, Canada. The paper describes a methodology to optimally select, site, size, control, and integrate distributed generation and storage units with the existing Campus power system. The proposed approach enables optimal operation of the Campus power system in both grid-tied and autonomous modes of operation. Two control strategies are selected, implemented, and tested to permit the safe and efficient integration and operation of the on-site DER units into the Campus power system during the grid-tied and islanded modes of operation. Moreover, a smart and accurate fault detection, isolation, and service restoration (FDISR) algorithm is proposed and implemented, based on a bidirectional communication infrastructure, to support the Campus power system operation in the presence and absence of the utility bus. Finally, the results of one the conducted case studies are reported and analyzed to evaluate the impacts of the proposed power management and control strategies on the performance of the BCIT Microgrid as well as the interaction between different on-site DER units and the utility.

A demand response system has been installed in the Village of Hartley Bay, a remote community in BC, Canada, with the intent improving overall general dispatch efficiency. This community of 170 people is supplied by a small electrical network that is powered by three diesel generators. The demand response system is being developed to shed or add demand when a predictive algorithm, “the typical curve,” estimates an inefficient peak is to occur. Variable thermostats and 30 amp load controllers were installed in the commercial facilities to shed loads in, e.g., the school, health center, and community center. The total shed capacity is 20 percent of the typical maximum winter demand. Initial results indicate an unnoticed change in level of service to the community and an unexpected benefit of energy conservation with limited rebound and an anticipated energy reduction of up to 3 per cent.

Photovoltaics (PV) is considered a non-controllable power source which can create overvoltages in distribution feeders during periods of high generation and low load. This is usually prevented by limiting the penetration level of PV to very conservative values, even if the critical periods rarely occur. This paper discusses the use of droop based active power curtailment (APC) techniques for overvoltage prevention in radial low voltage (LV) feeders as a means for increasing the installed PV capacity and energy yield. Two schemes are considered and tested in a typical 240V/75kVA Canadian suburban distribution feeder with 12 houses equipped with roof-top PV systems. In the first scheme, all PV inverters have the same droop coefficients. In the second, the droop coefficients are proposed to be different so as to share the total active power curtailed, and consequent loss of revenue, among all PV inverters/houses. Simulation results demonstrate the effectiveness of the droop based APC schemes and that the option of sharing the power curtailment among all customers comes at the cost of an overall higher amount of power curtailed.

Soil testing and leaf analysis have been used as one of the measures for indicating fertilizer needs on country level, and thus fertilizer allocation. In 1976, a project was initiated to introduce soil testing and leaf analysis as a base for working out specific fertilizer recommendations on farmer's level and as monitoring system for crop nutritional status. Three well equipped laboratories were established and surveys were carried out. In 1981, services were made available to farmers, co‐operatives, farmers organizations, etc. Highly qualified field personnel is advising farmers, interpreting analytical results and working out fertilizer recommendations. Services are partially paid by the beneficiaries. During 1985–1988 service was rendered to about 22,000 farmers. In the meantime, a program was set up to establish service laboratories throughout the country. Eleven were initiated, but still not established to serve the farmers directly. However, they help in indicating fertilizer needs of the ...

This paper presents a new technique for regulating grid-connected wind farms terminal voltage. The wind farm under investigation is assumed equipped with doubly-fed induction generators (DFIGs). The proposed technique is based on using the grid-side converter to regulate the farm's terminal voltage rather than using the rotor-side converter to achieve this task. Description for the studied system with the used dynamic modeling equations and detailed illustrations for the control loops block diagrams are presented. Simulation results for different operating conditions are also presented to reveal the accuracy of the proposed technique. Finally, Corresponding simulation results under unity power factor operation conditions are presented to demonstrate the effectiveness of the control technique.

This paper surveys the state of arts of microsensors and microactuators. The first part of this survey introduces microsensors from the points of view of their classification principles of operation performance parameters and applications in robotic mechanisms. The second part concentrates on microactuators from the points of view of their classification principles of operation and of application in robotics

The growing revolution in wind energy encourages for more accurate models for wind speed forecasting and wind power generation prediction. This paper presents a new technique for wind speed forecasting based on using a time series model relating the predicted interval to its corresponding one and two year old data. A set of data that extends to 72 hours is used in investigating the accuracy of the model for predicting wind speeds up 24 hours ahead. Obtained results, form the proposed model, are compared with their corresponding values generated when using the persistence model. The presented results validate the effectiveness of the new prediction models for wind speed.

The generation of electrical power in isolated remote areas depends on the utilization of renewable energy resources such as wind, solar and geothermal energies. Self-excited induction generators (SEIG) have been widely used in electric power plants utilizing wind energy. This paper introduces a digital simulation and a control technique of a stand-alone SEIG scheme driven by a wind turbine as an external mechanical prime mover. The SEIG scheme will be simulated under the PSCAD/EMTDC environment. The proposed control scheme consists of two parts. The first part controls the turbine blades pitch angle (/spl beta/) to compensate the variations in the rotor speed due to the variations in the wind velocity. The second part regulates the load voltage waveform in magnitude and frequency within the acceptable limits using a PWM inverter. Two Pl controllers will be used to provide the control signal for each of the two parts. Results are presented in the paper to demonstrate the effectiveness of the proposed control scheme.

This paper introduces a digital simulation using PSCAD/EMTDC environment for sensors to be used in measuring the wind speed, turbine rotational speed and wind flow direction. The paper also, simulate the actuators actions in order to adjust the blade pitch angle to maintain the desired speed of rotation as the wind speed changes and/or to rotate the Nacelle of the turbine to keep the rotor facing into the wind as the wind direction changes. Finally, the paper presents an introduction to the present work in the field of introducing MEMs based sensors and comb drive actuators to replace the traditional ones in wind turbines. As well as, illustrating the expected improvements in the performance of the wind turbine while using the MEMs devices.

The wind energy is used widely in the modern electrical systems. This paper proposes a novel functionality of the interface, between the self excited induction generator (SEIG) coupled with a wind turbine and the utility network, not only to control the active power flow, but also to mitigate the voltage flicker and regulate the voltage at the point of common coupling (PCC). In order to achieve this and to ensure constant DC supply for the STATCOM, the generated voltage of the SEIG is rectified and the DC-side voltage is controlled using a DC-chopper. The SEIG will be modeled under the EMTDC environment using the FORTRAN compiler. Simulations of the suggested scheme are conducted to evaluate the performance of the novel system.

Nitrogen use per unit area in Egyptian agriculture is over 300 kg ha-1. An annual average increase of about 2% till year 2000 was estimated. Fertilizers use is characterised by excessive N application, moderate P use and neglection of K and micronutrients. Consequently, nutrient imbalance occurs in crop plants. Subsidising N fertilizers resulted in their misuse and increasing losses. Efficiency of N use in different areas and crops is low. High nitrate concentrations were detected in drainage as well as ground water. Subsidy was removed and fertilizers handling was left to the free market in 1992/93, which resulted in drastic price increases. It could be demonstrated for many years and in farmers fields that yields can be considerably increased (20%) through balanced fertilizers use based on soil testing and plant analysis and adjusted according to the prevailing farming system, leading to more return and less N-use. Use of micronutrients foliar fertilizers leads to increase in root growth and higher uptake of macronutrients. Use of relatively high rates of fertilizers is still a must, however it should be optimised to obtain the highest possible efficiency. Making crop and location specific fertilizer recommendations available to farmers helps in increasing high quality yields, which results in high economic benefits, keeping agricultural production sustainable and decreasing pollution.

The content of exchangeable pottasium (K) in soil is a widespread international parameter of the K-status of a soil. The use of this parameter in Egypt suggests that alluvial soils are extremely rich in K, and that sandy and calcareous soils are low in this nutrient. However, the content of total K in citrus leaves was found to be unsatisfactory in orchards on alluvial soils. The reason is that K uptake by citrus is hindered by K fixation in clay and is antagonized by other cations. Annual applications of fertilizer K, combined with a balanced nutrition regarding other nutrients was found to increase fruit yield in citrus orchards. It was concluded that for higher and better citrus orchards, not only those on poor sandy and calcareous soils, but also those on Nile-alluvial soils are in need of annual K-fertilizer applications. It could further be concluded that the use of exchangeable soil K as index of K availability should be reconsidered under Egyptian conditions.

A new technique for one step ahead average hourly wind speed forecasting and wind turbines' output power prediction based on using the Grey predictor models is presented. The required mathematical formulation for developing the Grey predictor models is also presented. The obtained results from the proposed models are compared with the corresponding results obtained when using the persistent model. Utilising the traditional Grey model, GM(1,1) was first investigated and showed good improvement over the persistent model. However, the generated results demonstrate the presence of intervals with overshoots in the predicted values. To reduce such overshoots, a modified version for the Grey predictor model referred to as the adaptive alpha GM(1,1) model is investigated and two new models are proposed, hereafter, referred to as the improved Grey model and the averaged Grey model. The presented results demonstrate the effectiveness, the accuracy and the superiority of the proposed averaged Grey model for wind speed and wind power prediction.

This paper introduces a computer-based model and dynamic simulation of a combined electro-mechanical control technique for a stand-alone wind turbine generator system. The presented combined control technique consists of three closed loops for speed regulation, nacelle alignment and dynamic load voltage regulation. Speed regulation is achieved by adjusting the pitch angle of the turbine blades. This pitch angle control has been widely investigated for wind turbines equipped with synchronous generators and grid-connected wind turbines equipped with induction generators, but not for stand-alone turbines equipped with induction generators as presented in this paper. A new dynamic model for the wind turbine is presented by adopting the aerodynamic equations that represent the differential power generated by each element (segment) of the turbine blade; then, the trapezoid rule (TRAP (n)) is applied to calculate the total generated power. The results are presented to prove the effectiveness of the presented electro-mechanical control technique.

A field survey has been conducted in Salalah region, Sultanate of Oman to evaluate the nutrient status of some horticultural crops and the respective soils. Soil and leaf samples were collected and analyzed. Soils were found to be characterized by high pH, high CaCO3 content, low or very low micronutrient contents. The unfavorable conditions caused nutrient deficiencies within the plant tissues. To correct the situation, fertilizer use should be based on soil testing and plant analysis, as well as information on farming system and farm management. Use of micronutrient fertilizers should be considered as a part of the fertilizer regime.

Egypt faces the prospect of rapid growth of populatlon which is a vital problem since agricultural land is not available at the same rate. More land should be reclaimed through development of water resources. The Nile river constitutes an immense water supply but one third of its water is lost through pumping low salinity drainage water to the Mediterranean Sea utilizing costly electric power. Therefore, feasibility studies on recycling this water must be carried out. Along the banks of the Nile, drinking water could be obtained supplied through either small water purification plants or electrodialysis desalination plants, and the economics of the two methods should be compared before deciding on either method. Another source is underground water with a salinity varying between 2000 and 11,000 ppm. For such brackish water, either the electrodialysis or reverse osmosis process can be used. Then there is the Egyptian sea shore which extends over 3000 km. and where the salinity of the sea varies between 33,000 and 45,000 ppm. Here flash distillation processes are suitable. The present paper briefly describes available water resources in Egypt and discusses possible solutions to supplying the fresh water required in different areas. The present investigation concentrates on the feasibility and economics of utilizing the electric supply from the grid at periods other than the peak loads for operating electrodialysis plants. It is estimated that a series of electrodialysis plantsrunning for lOh/day would provide 2.6 million m 3 /day at an operating cost of 10¢/m 3 in addition to capital costs.

Reclamation of sandy and calcareous desert lands in. Egypt for intensive cropping has considerable effect on the fertilizer requirement for most crops. The yield records, together with frequent visual appearances of micronutrient deficiency symptoms on economically important crops were the main reasons for investigating the status of micronutrients in these areas by means of leaf and soil analyses. Sites were selected to represent sandy and calcareous soils in newly reclaimed areas as well as loamy alluvial ones in the Nile‐Valley and Delta. Over 10000 soil and leaf samples were collectes in the last 5 years to evaluate the soil/plant fertility status within the area. The major deficiencies were found to be of Fe Mn and Zn revealed in both soil and plant analyses. Regarding soil type effects, Fe‐deficiency dominated on calcareous soil, Zn‐deficit on the sandy soils and Mn‐deficiency mostly on alluvial soils. Leguminous crops were most sensitive to Fe‐deflciency whereas cereals; especially maize a...