S. M. Lutful Kabir

Design of an intelligent SMS based remote metering system

Automatic Meter Reading (AMR) is a state-of-the-art technology for reading electric, gas or water meter readings automatically from a remote place without any human intervention. Remote metering promises fast and accurate billing system. In this paper, a technique for remotely reading electricity meter readings using Short Message Service (SMS) has been illustrated. Existing Global System for Mobile communications (GSM) networks have been used for sending and receiving SMS. A prototype of the system has been designed and developed for system exploration and experiment.

Standard and interoperable database for pre-paid electricity metering systems in Bangladesh

A generalized database has been designed for the prepaid system to be used for the metering purpose in electrical utility organizations. The prepaid metering systems currently used under different utility organizations have been studied thoroughly. The variations of the databases and systems from one utility to other are pointed out and generalization is devised in the new design. Considering the existing prepaid systems the proposed system has been designed. In the proposed system, a new concept of vending has been devised. This is termed as “Disintegrated Vending System”. Based on the proposed vending system, the generalized database has been designed following the guideline depicted in HL7 Reference Information model. The design has been completed by drawing the E-R model for an application. The logical design is then extended to physical model which in turn is used to design the table structures for the proposed database.

Inclusion of slack bus in Newton Raphson load flow study

Load flow solution is an inevitable tool for power system planning and operation. Among various methods of load flow solution techniques Newton Raphson (N-R) and its derivatives are the most popular and widely used ones. In Newton Raphson method one of the generator buses is treated as slack bus which is kept out of calculation during iterations. This is because of the fact that the slack bus is to carry entire loss of the system and total loss cannot be calculated before the end of iterations. The exclusion of slack bus from the load flow iteration restricts many analyses to make. Consideration of distributed slack bus, load flow for Microgrids, study on minimization of system losses etc. cannot be performed when the slack bus is excluded from the iterations. This paper reports the development of a method of including slack bus into the Jacobians for N-R load flow study. The method involves formulating the loss equation and then devising the formula for the terms to be included with the elements of the Jacobian matrix. The modified N-R method is applied to all of the buses and the losses are calculated in each iteration and included with the slack bus. The results obtained using the modified method are compared with those using conventional method. The agreement of the results confirms the accuracy of the developments.

Compensation for neglecting stator transients in power system models

ABSTRACT An accurate simple model of alternators for power system stability studies has been developed. The model is based on a detailed model [1] the validity of which has been verified earlier. The simplification is achieved by omitting stator and transmission line transients from the detailed model and introducing a compensation for the omission. It has been shown that the compensation has to be included at every time step. Since the order of the model is lower than the detailed one its computational speed is faster and memory requirement is less. The accuracy of the simple model including the compensation has been proved to be outstanding by comparing the results of the model with those obtained from the detailed model

Solar powered ferry boat for the rural area of Bangladesh

Bangladesh is a riverine country. Ferry boats are the major means of communication in the rural area. Diesel is used as the fuel in the engine boats used for transporting people from one side of a river bank to the other. To avoid environmental pollution solar powered boat is proposed. A conventional ferry boat is converted into solar powered ferry boat. A complete design process is described in this paper. Following the design process, the boat has been retrofitted with 48V, 500W BLDC motor, 1kW Solar panel with 9600 VAh Battery. The boat is 6.5 meter long and 2 meter beam, capable of carrying 1200kg load for 8 hours. The approximate speed of the boat is measured as 3knots, which is capable of covering 60 km distance in one full charge.

A localization algorithm for capsule endoscopy based on feature point tracking

Wireless Capsule Endoscopy (WCE) has emerged as a popular non-invasive imaging tool for inspection of human Gastrointestinal (GI) tract. In order to identify the location of an anomaly or intestinal disease, the physicians need to know the exact location of the endoscopic capsule which influences the treatment plan. In this paper, we present a displacement estimation technique based on feature point tracking which utilizes the images captured by a commercial capsule, named PillCam. The proposed displacement calculation approach is tested using a virtual testbed. Results show that, with assistance of ASIFT-RANSAC algorithms, the proposed algorithm is able to estimate the linear displacement of the endoscopic capsule with an accuracy of 93.7% on average.

Range adaptation of Wireless Power Transfer systems for biomedical applications

The circuit components of a Wireless Power Transfer (WPT) system are designed considering a fixed separation distance and fixed alignment between the transmitting and receiving sides of the WPT system. But, in practice, the separation distance and the alignment do not remain constant. This is especially true for a biomedical application where a moving instrumental part requires electric power. This change causes a variation in mutual coupling and consequently in the efficiency of the system. This paper describes how to maintain the efficiency more or less constant even if the separation distance and the alignment vary. First of all, the circuit elements for maximum efficiency are worked out, then simulation for various separation distances and misalignment are calculated. A means of controlling a particular parameter is worked out in order to maintain efficiency of the system more or less constant.

Effect of generator saturation on shaft torques during faulty synchronization

Torque developed during a short circuit of an alternator is considered as the most severe case for the design of the shaft by engineers. But studies show that shaft torque during a faulty synchronization may exceed the torque developed during a short circuit at certain conditions. Accurate prediction of the shaft torque in faulty synchronization process is therefore important in the design stage to ensure the safe operation of ac generators. In the reported simulations the effects of saturation is either neglected or taken into consideration in the form of mutual path saturation only. The procedure may provide underestimated values of shaft torque because the current involved in such a situation may become significantly high at certain synchronizing angle. Hence, simulations should consider leakage path saturation during shaft torque evaluation particularly during short circuits and faulty synchronization. This paper describes a method of simulating faulty synchronization of a generator to a power system considering a detail generator model in mathematical and state space form. A method of incorporating saturation effects both in the mutual and leakage path is proposed. Simulations have been carried out for different synchronizing angles to evaluate the instantaneous and the peak shaft torques with and without saturation effects. Finally, a typical comparative study between faulty synchronization and short circuit faults of ac generators is provided in this paper, where, the results of faulty synchronization conditions were evaluated by proposed simulation method presented in this paper.

Estimating the fall in generator voltage following an impact load

Abstract Equations have been derived for calculating the changes in voltage that occur at the terminals of an alternator following the sudden application of a load. The influence of saturation within the machine, at the instant of application and during the subsequent transient, on the performance of the machine is defined. Rules are outlined to accommodate saturation when applying the equations so that voltage changes can be calculated accurately whatever the initial and shock load conditions. The effectiveness of the equations and techniques outlined are demonstrated in tests on a micromachine model and on a practical alternator.