POWER CONTROL AND OPTIMIZATION: Proceedings of the 3rd Global Conference on Power Control and Optimization
1239(2010); http://dx.doi.org/10.1063/1.3459784View Description Hide Description
The continued scaling of semiconductor devices and the difficulties associated with time and cost of manufacturing these novel device design has been the primary driving force for the significantly increased interest in Computational Electronics which now, in addition to theory and experiments, is being considered as a third important mode in the design and development of novel nanoscale devices. In addition to its significant role in industrial research, modeling and simulation also brings into the picture alternative education modes in which students, by running certain subset of tools that, for example, the nanoHUB offers, can get hands‐on experience on the operation of nanoscale devices and can also look into the variation of internal variables that can not be measured experimentally, like the spatial variation of the electron density in the channel in the pre‐ and post‐pichoff regime of operation, electric field profiles which can be used to tailor the electron density to avoid junction breakdown, etc. In summary, Computational Electronics is emerging as a very important field for future device design in both industry and academia.
1239(2010); http://dx.doi.org/10.1063/1.3459740View Description Hide Description
This paper discusses some important fundamental issues behind application of renewable energy (RE) to evaluate its impact as a climate change mitigation technology. The discussed issues are the following: definition of renewable energy, concentration of RE by weight and volume, generation of electrical energy and its power at unit area, electrical energy demand per unit area, life time approach vs. layman approach, energy return time, energy return ratio, return time, energy mix for RES production and use, geographical distribution of RES use, huge scale of energy shift from RES to non‐RES, increase in energy consumption, Thermodynamic equilibrium of earth, and probable solutions for energy future of our energy and environmental crisis of today.
The future solution (that would enable to human civilization further welfare, and good living, but with lower release of in atmosphere) may not be only RES. This will rather be an energy mix that may contain nuclear energy, non‐nuclear renewable energy, or fossil energy with sequestration, efficient energy technologies, energy saving, and energy consumption decrease.
1239(2010); http://dx.doi.org/10.1063/1.3459758View Description Hide Description
Faults always contribute significantly in disturbing the reliability and security of an integrated electrical power system. This requires the considerable attention of researchers and power industry stake holders to address these issues using latest instrumentation techniques. For this purpose a practical power system of 132 kV Grid has been selected for comprehensive analyses using Electrical Transient Analyzer Program (ETAP) software for Transient, Short circuit and Ground Grid analyses. In Transient analysis different waveforms like variation in bus frequency, bus real power loading, bus voltage angle and bus reactive power loading have been recorded for short interval of time. During Ground Grid modeling which is based upon practical data, step and touch potential have been calculated in comparison with set standards. While performing short circuit analysis all the possible short circuit faults like line to ground, double line to ground 3‐phase faults etc on cycle, 1.5 to 4 cycle and 30 cycle networks have been performed to record the short circuit currents. These real time data analyses provide opportunity to utilities about the remedial measures for the issues high‐lighted in them.
1239(2010); http://dx.doi.org/10.1063/1.3459766View Description Hide Description
This paper describes the optimization of conductor size and the voltage regulator location & magnitude of long rural distribution lines. The optimization minimizes the lifetime cost of the lines, including capital costs and losses while observing voltage drop and operational constraints using a Genetic Algorithm (GA). The GA optimization is applied to a real Single Wire Earth Return (SWER) network in regional Queensland and results are presented.
1239(2010); http://dx.doi.org/10.1063/1.3459783View Description Hide Description
Growing uncontrolled electrical demands have caused increased supply requirements. This causes volatile electrical markets and has detrimental unsustainable environmental impacts. The market is presently characterized by regular daily peak demand conditions associated with high electricity prices. A demand‐side response system can limit peak demands to an acceptable level. The proposed scheme is based on energy demand and price information which is available online. An online server is used to communicate the information of electricity suppliers to users, who are able to use the information to manage and control their own demand. A configurable, intelligent switching system is used to control local loads during peak events and mange the loads at other times as necessary. The aim is to shift end user loads towards periods where energy demand and therefore also prices are at the lowest. As a result, this will flatten the load profile and avoiding load peeks which are costly for suppliers. The scheme is an endeavour towards achieving a dynamic smart grid demand‐side‐response environment using information‐based communication and computer‐controlled switching. Diffusing the scheme shall lead to improved electrical supply services and controlled energy consumption and prices.
1239(2010); http://dx.doi.org/10.1063/1.3459785View Description Hide Description
The main emphasis of this paper is on the engineering economics and design developments in the field of thermal power generation in Pakistan.
Pakistan is rich with coal fields but is making no use of this available natural resource to fulfil its energy demands. The shortage of power is getting worst day by day and to align with the power requirements, Pakistan needs to add 2000 MW each year to national grid.
With the increasing prices of natural gas and oil , Pakistan should consider coal , the abundantly available natural resource, as an alternate fuel for its new power plants to overcome the power crises.
1239(2010); http://dx.doi.org/10.1063/1.3459786View Description Hide Description
This paper presents Genetic Algorithm (GA) based approach for the allocation of FACTS devices for the improvement of Power transfer capacity in an interconnected Power System. Simulations are done on IEEE 30 BUS System. The result obtained by the GA (Genetic Algorithm) approach is compared with that of obtained by PSO (Particle Swarm Optimization) method. The comparison shows how the system performance can be greatly improved with the GA based proposed approach.
OPTIMAL ALLOCATION AND SIZING OF CAPACITORS TO MINIMIZE THE TRANSMISSION LINE LOSS AND TO IMPROVE THE VOLTAGE PROFILE1239(2010); http://dx.doi.org/10.1063/1.3459787View Description Hide Description
To allocate and size capacitors in a distribution system, an optimization algorithm, called Discrete Particle Swarm Optimization (DPSO), is employed in this paper. The objective is to minimize the transmission line loss cost plus capacitors cost. During the optimization procedure, the bus voltage, the feeder current and the reactive power flowing back to the source side should be maintained within standard levels. To validate the proposed method, the semi‐urban distribution system that is connected to bus 2 of the Roy Billinton Test System (RBTS) is used. This 37‐bus distribution system has 22 loads being located in the secondary side of a distribution substation (33/11 kV). Reducing the transmission line loss in a standard system, in which the transmission line loss consists of only about 6.6 percent of total power, the capabilities of the proposed technique are seen to be validated.
PRACTICAL GENETIC ALGORITHM BASED OPTIMAL CAPACITOR PLACEMENT FOR LOSS REDUCTION AND VOLTAGE REQULATION IN DISTRIBUTION SYSTEMS1239(2010); http://dx.doi.org/10.1063/1.3459788View Description Hide Description
Optimal capacitor placement is a procedure to find optimal location and size of capacitors in distribution systems in order to follow some specific proposes. With this explanation, a proper capacitor placement can be considered as an effective scenario to improve system reliability and reduce energy losses.
In this paper, a new practical method is presented to find optimal place and size of capacitors such that it minimizes the power losses and reduces the overall cost of the distribution system.
Due to the non‐linear objective functions and constraints equations, Genetic Algorithm is used which will be an ideal candidate to well solve this type of optimization problem where the new heuristic techniques applied in this paper cause a significant improvement in voltage profile with fast computation time.
The effectiveness of the proposed method is demonstrated through several examples and the results are compared with some other methods.
1239(2010); http://dx.doi.org/10.1063/1.3459789View Description Hide Description
Presently along with traditional insulators i.e. glass and porcelain, etc., the polymeric insulators are also used world widely. These polymeric insulators are very sensitive to various environmental parameters e.g. UV radiations, heat, etc. The UV radiation level in the central region of Saudi Arabia is high as compared to the recommended IEC‐61109 standard for the accelerated aging of the composite insulators. In this study, thermoplastic elastomer (TPE) and Ethylene Propylene Diene Monomer (EPDM) insulators were subjected to accelerated aging stress as per IEC standard as well as modified IEC standard simulating the inland arid desert’s atmospheric conditions. The hydrophobic characteristics were studied by measuring the contact angle along the insulator surface before and after the accelerated aging of the samples. It was found that TPE loses its hydrophobic properties more as compared to EPDM insulator. This loss was proportional to the intensity of UV irradiation. The rate of recovery is also low for both the tested materials as compared to Silicone Rubber insulators.
1239(2010); http://dx.doi.org/10.1063/1.3459790View Description Hide Description
The South African electrical supply utility (Eskom) has been experiencing problems in the field of protection, maintenance and in‐service breakdowns which influence the quality of electrical supply to the consumer, an important and integral component of the utility business. As a result, further development of the generic relay, implemented as a strategic spare relay for the replacement of several schemes operating within Eskom’s southern region has been initiated. These include the electromechanical, solid state and numerical distance protection relays and scheme failures on the 132/66 kV feeder network . The research considers the development, testing and configuration of the strategic spare relay in terms of software and peripheral hardware for the input and output terminal connections, generic equations and settings, for the purpose of scheme replacements. The various schemes are assessed for stepped distance and permissive intertripping for three and single pole operation. This is done in conjunction with the internal and external circuit diagrams to understand the detailed operation of the scheme and to ensure the effective implementation of the strategic spare relay . The generic relay is configured for the emergency replacement of the various schemes during in‐service breakdowns . This constitutes a temporary installation and therefore the downtime of all the distance protection schemes that require replacement, is limited to a minimum.
1239(2010); http://dx.doi.org/10.1063/1.3459791View Description Hide Description
This article is intended to guide industry to effective implementation of Reliability Centered Maintenance (RCM) by identifying the pitfalls to avoid, by introducing new concepts that make RCM simple, by discussing the uncomplicated tools needed to commence the RCM analysis, by explaining the step‐by‐step RCM implementation logic process with actual real life examples, and the step‐by‐step explanation of the preventive maintenance (PM) strategies, by explaining how to establish an RCM living program, by explaining how to monitor and trend performance of the RCM program. Finally by knowing when the optimum balance point of the RCM efforts have been a chieved.
POWER SYSTEM RELIABILITY ASSESSMENT BY ANALYSING VOLTAGE DIPS ON THE BLUE HORIZON BAY 22KV OVERHEAD LINE IN THE NELSON MANDELA BAY MUNICIPALITY1239(2010); http://dx.doi.org/10.1063/1.3459792View Description Hide Description
Power system reliability problems are very difficult to solve because the power systems are complex and geographically widely distributed and influenced by numerous unexpected events. It is therefore imperative to employ the most efficient optimization methods in solving the problems relating to reliability of the power system . This paper presents a reliability analysis and study of the power interruptions resulting from severe power outages in the Nelson Mandela Bay Municipality (NMBM), South Africa and includes an overview of the important factors influencing reliability, and methods to improve the reliability. The Blue Horizon Bay 22 kV overhead line, supplying a 6.6 kV residential sector has been selected. It has been established that 70% of the outages, recorded at the source, originate on this feeder.
1239(2010); http://dx.doi.org/10.1063/1.3459737View Description Hide Description
In this paper, a circuit model is devised to analyze nonlinear behaviour of quantum cascade lasers . Such nonlinear behavior influences the light output when the laser is driven by currents comparable to the average (DC) current. The simplified 2‐level rate equations are first improved. Next, the circuit model is obtained following the approach for interband lasers. The difference between the circuit models of quantum cascade lasers and interband lasers is pointed out. The circuit model is simpler compared to that obtained from a 3‐level model. Unlike a circuit model derived earlier from the 2‐level model, the present model can handle both small and large current drives .
1239(2010); http://dx.doi.org/10.1063/1.3459738View Description Hide Description
A simple model of a DC motor driving an inertial load has the angular rate of the load, ω, as the output and applied voltage, as the input. The ultimate goal of this paper is to control the angular rate by varying the applied voltage using different control strategies for comparison purpose. The comparision is made between the proptional controller, integral controller, propotional and integral controller, phase lag compensator, derivitive controller, lead integral compensator, lead lag compensator, PID controller and the the linear quadratic tracker design based on the optimal control theory.
1239(2010); http://dx.doi.org/10.1063/1.3459739View Description Hide Description
Matlab SimPowerSystems is a modern design tool that allows scientists and engineers to rapidly and easily build models that simulate power systems. Not only can you draw the circuit topology rapidly, but your analysis of the circuit can include its interactions with mechanical, thermal, control, and other disciplines. The paper covers some case studies that provide detailed, realistic examples of how to use SimPowerSystems in power system analysis. The following types of studies is coverted on the paper:
1. Thyristor‐Based Static Var Compensator: Study the steady‐state and dynamic performance of a static var compensator (SVC) on a transmission system.
2. Transient Stability of a Power System with SVC and PSS: Study of the application of static var compensator (SVC) and power system stabilizers (PSS) to improve transient stability and power oscillation damping of the system.
3. GTO‐Based STATCOM: Study the steady‐state and dynamic performance of a static synchronous compensator (STATCOM) on a transmission system.
4. Control of load flow using UPFC: Study the steady‐state and dynamic performance of a unified power flow controller (UPFC).
5. Chopper‐Fed DC Motor Drive: Study of a DC motor drive with armature voltage controlled by a GTO thyristor chopper.
6. VSC‐Based HVDC Link: Modeling of a forced‐commutated Voltage‐Sourced Converter high‐voltage direct current (VSC‐HVDC) transmission link.
7. Three‐Phase Network with Electrical Machines: Simulation of a three‐phase power system containing electrical machines and other three‐phase models.
8. Variable‐Frequency Induction Motor Drive: Study of a PWM inverter‐driven variable‐frequency AC induction motor in variable‐voltage, variable‐speed operation.
1239(2010); http://dx.doi.org/10.1063/1.3459741View Description Hide Description
This paper presents a method of how to design a centrally coordinated controller for several HVDC links. The controller increases the damping of the power oscillations by modulating the current through the HVDC links coordinately. To design a centrally coordinated controller a reduced order open system model is estimated. The open system model of the power system is developed by using black‐box system identifications techniques. The current setpoint change through the HVDC links is the set of input signals and, the speeds of the generators are the set of outputs. Numerical Algorithms for Subspace State‐Space System Identification (N4SID) is used to identify a model. This controller design method increases the damping significantly which is shown for a small power system.
HYBRID PWM SWITCHING STRATEGY FOR A THREE‐LEVEL INVERTER FED INDUCTION MOTOR DRIVE WITH OPEN‐END WINDINGS1239(2010); http://dx.doi.org/10.1063/1.3459742View Description Hide Description
A dual two‐level inverter fed induction motor with open‐end windings is capable of generating a three‐level output voltage. Several, sine‐triangle and space vector pulse width modulation (PWM) switching strategies are presented for the dual‐inverter scheme either using space‐vector or carrier‐based implementation. In this paper, a hybrid PWM switching strategy for the dual‐inverter scheme is proposed employing sine‐triangle PWM (SPWM) and space vector PWM (SVPWM) for the individual inverters. SPWM is theoretically analyzed and space vector based implementation of SPWM is presented using a simple offset‐time concept. This is exploited to implement the hybrid PWM switching strategy for the dual two‐level inverter. The implementation of the hybrid PWM switching strategy proposed in this paper do not require any look‐up tables, the switching is totally automatic obviating the time‐consuming task of sector identification. The implementation of the hybrid PWM scheme requires only the three instantaneous phase reference voltages corresponding to the reference space vector. The third harmonic component in the voltage appearing across the motor phase windings in the induction motor is significantly reduced (by 50%) with the use of the proposed hybrid PWM scheme as compared to the use of the PWM scheme presented earlier. Also, the percentage weighted total harmonic distortion (%WTHD) of the output voltage is significantly reduced in the entire range of speed of the induction motor driven by the dual‐inverter scheme.
1239(2010); http://dx.doi.org/10.1063/1.3459743View Description Hide Description
Solar energy is rapidly advancing as an important means of renewable energy resource. More energy is produced by tracking the solar panel to remain aligned to the sun at a right angle to the rays of light. This paper describes in detail the design and construction of a prototype for solar tracking system with two degrees of freedom, which detects the sunlight using photocells. The control circuit for the solar tracker is based on a PIC16F84A microcontroller (MCU). This is programmed to detect the sunlight through the photocells and then actuate the motor to position the solar panel where it can receive maximum sunlight.