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A Reliable Method for the Solution
of the Load Flow Problem
-- R P Sharma and Satyavir Singh
This paper presents a reliable method for the solution of the load flow problem. This new method
includes simplicial subdivisional approximation for the solution of the nonlinear function. This method provides at
least one solution when the solution is unique. It is also capable of finding multiple solutions, if existing, with
the same arbitrarily chosen initial solution point even at far-off distance. The size of matrix in this method
is considerably less as compared to NR or NR-type methods. The special feature of this method is its
reliability. The experimental results are presented in a hybrid power system model for the period 2006-10, which
show the feasibility of the approach.
© 2011 IUP. All Rights Reserved.
Hybrid Speed Control of Sensorless Brushless
DC Motor with Fuzzy-Based Estimation
-- B Mahesh Kumar, G Ravi and R Chakrabarti
This paper describes a simple way to control the Brushless DC (BLDC) motor for electrical applications.
To control this machine, it is generally required to measure the speed and position of the rotor by using the
sensor, because the inverter phases acting at any time must be commutated depending on the rotor position.
Encoders and resolvers have been used for sensing the rotor position with respect to the stator. These sensors,
however, make the motor system more complicated and mechanically unreliable. A method for the estimation of
the speed and rotor position of a BLDC motor is presented in this paper. Fuzzy-based back-EMF observer
is employed to estimate the speed by using measurements of the stator line voltage and line current.
Most existing sensorless methods of the BLDC motor have low performance in a transient state or low-speed
range and occasionally require an additional circuit. To overcome this problem, the estimation of back-EMF
is carried out by fuzzy logic techniques to improve the performance of the system. This method proposes a
back-EMF observer based on fuzzy function approximation and the system state equation of the BLDC
motor and describes a fuzzy logic approach to design a Hybrid Controller (HC) for variable speeds of a BLDC
motor. Here, Proportional Integral (PI) controller is tuned by the fuzzy logic technique. The fuzzy logic tuner is
used to adjust the two gains of the PI controller. In this approach, the fuzzy tuning of the gains of a conventional
PI controller is achieved through fuzzy rules deduced from many simulation tests applied to BLDC motor, for
a variety of operating conditions. Experimental results show that the proposed fuzzy-tuning PI controller
is better than the controller with fixed gains in terms of robustness and speed rise time even under great
variations of operating conditions and load disturbance.
© 2011 IUP. All Rights Reserved.
Biometric Fingerprint Segmentation
Using Kernel Fuzzy C-Means Clustering
on Level Set Method
-- Tara Saikumar, P Srinivasa Murthy and B Premlatha
In this paper, Kernel Fuzzy C-Means (KFCM) algorithm was used to generate an initial contour curve
which overcomes leaking at the boundary during the curve propagation. First, the KFCM algorithm computes
the fuzzy membership values for each pixel. On the basis of the KFCM, the edge indicator function was
redefined. Using the edge indicator function, the biometric fingerprint segmentation of a medical image was performed
to extract the regions of interest for advanced processing. In this process, the complexity of time iteration
is reduced compared to the Fuzzy
C-Means (FCM) algorithm. The above process of segmentation showed a considerable improvement in
the evolution of the level set function.
© 2011 IUP. All Rights Reserved.
Reliability Evaluation of a Distribution System
-- G N Sreenivas, P Sangeetha, A Anil Kumar and E Vidyasagar
Distributed Generation (DG) technique has achieved prodigious progress recently. The distributed
generator, normally defined as a small generating unit (<10 MW) installed in the distributed system, is expected to play
an increasing role in the emerging power system and thus improve the reliability of the system and load
point indices. Normally, distributed generators are installed near the customer side so as to have a great impact
on the power system, especially on the distributed system. Reduction of system expansion costs, decreasing
loss of power and reliability enhancement are some of the benefits of DG application. In this paper, an
appropriate model is developed to assess the impact of DG on reliability indices. An analytical probability approach
is developed for this study. Reliability indices of distribution system are evaluated without DG, with DG,
and swapping two DGs using the model developed. The indices thus obtained are compared. The
analysis demonstrates that the DG has the ability of improving the reliability of system. It provides some
useful conclusions such as the impact of the site of the DG on the reliability of the distribution system. It can
be observed from a comparison of the results that when system obtains the large capacity DG is installed,
the higher reliability level.
© 2011 IUP. All Rights Reserved.
ANN Controller-Fed PMDC Drive
for Paper Mills
-- R Sankar and S Ramareddy
The aim of this work is to improve the tracking performance of separately excited DC motor by exploring
the features of Artificial Neural Network (ANN). The neural network controller enhances the performance
and dynamics of the DC motor in comparison to conventional Proportional Integral (PI) controller. The
simulations are carried out with MATLAB simulink. The ANN-based PMDC drive is suitable for a vast number of
industries like paper mills, textile mills, etc.
© 2011 IUP. All Rights Reserved.
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