Abstract

Simple power electronic drive circuit and fault tolerance of converter are specific advantages of SRM drives, but excessive torque ripple has limited its use to special applications. Due to the nature of the torque production in SRM, the torque generated in any individual phase is discontinuous. To generate a ripple free output torque, there must be a overlapping between phases. To obtain a constant torque, the summation of the torque generated by the phase currents must be the same. In this work, a torque factor is defined to determine the torque required in each phase during overlapping to make a ripple free resultant torque according to the rotor position and the specified turn-on/turn-off angles. Then the torque command is converted into current command according to the inductance based SRM model. Finally voltage-chopping technique is used to generate voltage pulses for each phase to maintain the phase current around the desired value. Simulations show satisfactory results of the proposed method.

Abstract

A Space Vector Pulse Width Modulation (SVPWM) scheme for cascaded multilevel inverters is proposed in this paper. The proposed PWM scheme generates the inverter leg switching times, from the sampled reference phase voltage amplitudes and centres the switching times for the middle vectors, in a sampling interval, as in the case of conventional space vector PWM (SVPWM). The SVPWM scheme, presented for diode clamped multilevel inverters, can also work in the over modulation range, using only the sampled amplitudes of reference phase voltages. The present PWM technique does not involve any sector identification and considerably reduces the computation time when compared to the conventional space vector PWM technique. The present PWM signal generation scheme can be used for any multilevel inverter configuration.

Abstract

In this paper a pulse width modulated series parallel resonant converter is presented. The performance of the converter for constant output voltage with variable input and variable load is analyzed. This configuration is well suited for many applications where output is fairly constant but the input is required to vary widely without serious switching losses and with significant reduction in ripple content. Experimental results obtained from a laboratory prototype are presented.

Abstract

An embedded controlled single-switch parallel resonant converter is introduced for induction heating applications. The circuit comprises of an input LC-filter, a bridge rectifier and a controlled power switch. The switch operates in the soft commutation mode and serves as a high frequency generator. This scheme overcomes the shortcomings of the previous schemes i.e. the presence of the DC component in the load current. The steady-state analysis of the converter is given. The theoretical analysis and computer simulation satisfy the experimental results.

Abstract

Research into renewable energy sources has previously lacked sufficient investment. However, emphasis has now shifted and funding is being made available in a proactive manner by various governments eager to encourage renewable energy technology and reduce carbon taxes. Fuel Cells offer a realistic, sustainable and clean alternative energy option for stationary and mobile applications. Hydrogen and fuel cell technologies are recognised by many as possible long term energy solutions, but to-date, have failed to make an impact on the energy market. This is due to a number of key reasons, some of which include efficiency, scale, accessories and power output. For example, applying fuel cells to small telecommunication components requires the applications of Micro and Nanotechnology, which have yet to be perfected to make them long lasting and cost effective. This paper focuses on the design, engineering and development of a new Alkaline Fuel Cell outlining its capabilities and limitations for satisfying future energy needs in terms of its long term operation in air.

Abstract

Puerto Rico is a Caribbean island with an area of about 3,500 square miles. The Island is 99% dependent on fossil fuels for transportation and electricity, but there are no fossil fuels in PR. The Island’s has an inefficient and irresponsible energy use, and the demand increased dramatically in the 90s. The social, environmental and economic costs of current energy sources and practices are too high.

There is an urgent need for a social and technological transition to a new culture of social and environmental justice, based on sustainable practices and technologies. Solutions being sought and implemented are mostly economic, and in many times short term in nature.

In 1980 the U.S. National Academy of Sciences concluded that “Puerto Rico, in dealing with its own energy problems, should grasp its opportunity to become an international energy laboratory, seeking and testing solutions especially appropriate to the oil-dependent tropical and sub-tropical regions of the world.

Puerto Rico did not become the international energy laboratory it could have been. And after the initial uproar created by high oil-prices and short-term strategies vanish, we fall again in the complacency of “acceptable” oil prices. We remain waiting, as if the answer to our oil dependency problem could be imported.

This paper will discuss the Puerto Rican context as an example of Un-Sustainable practices, and present the results of a recent study that establishes that the Island has enough renewable energy resources to supply most of its energy needs. The challenges for a sustainable energy future are not only technical, or created by resource availability, the challenges are also, and mainly, social and environmental in nature.

Abstract

This paper deals with digital simulation of power system using UPFC to improve the power quality. The UPFC is also capable of improving transient stability in a power system. It is the most complex power electronic system for controlling the power flow in an electrical power system. The real and reactive powers can be easily controlled in a power system with a UPFC. The circuit model is developed for UPFC using rectifier and inverter models. The control angle is varied to vary the real and reactive powers at the receiving end. The Matlab simulation results are presented to validate the model.

Abstract

This paper presents a novel, completely decentralized Multi Agent System based reconfiguration methodology for Shipboard Power Systems. The objectives of the approach considered are: to design an Multi Agent System based reconfiguration structure, an algorithm that can break an arbitrary mesh structured Multi Agent System into tree structure to avoid redundant information accumulation problem and to develop a completely decentralized reconfiguration methodology. Software has been developed using C for the above work.

Abstract

In this paper a composite reliability evaluation of a practical distribution system is developed. The reliability of a substation is calculated using minimal cut-set technique. The interaction between distribution substation and primary distribution system is modeled according to the tripping behavior of feeder circuit breakers. Then, the contribution of reliability indices evaluated from the primary distribution system is added to the previous two effects. The primary indices (ë, r, U) and the secondary reliability indices such as customer oriented and load-energy oriented indices are calculated for four types of distribution configurations. The developed models reflect the effect of distribution substations, primary distribution systems, and the interaction between them. Comparisons of reliability indices are made.

Abstract

One of the requirements for the operation and planning activities of an electrical utility is the prediction of load for the next hour to several days out, known as Short Term Load Forecasting (STLF). Artificial neural network (ANN) techniques have been applied to various subjects in the electrical power system area including electric load forecasting. This paper presents an application of (ANN) to the weekly load forecast problem of Jordan National Power System (JNPS). The ANN is trained with the load patterns corresponding to the forecasting hours and the forecasted load is obtained. Time Series Regression (TSR) modifies the initial forecasted load. A Neural Network (NN) model for the prediction of the seven-day ahead peak load of Jordan power system is developed. For the purpose, Nonlinear Auto Regressive (AR) modeling, using simple Back-propagation NNs architecture, is used. This model was trained using two weeks data window for the most recent daily peak loads. The model treated the peak load at weekdays and weekends altogether. The results showed that the model has satisfactory results for one hour up to a week prediction of JNPS load. The average absolute  percent error for the generated forecasts using this model was 0.5%.