Physical Sciences and Engineering

A novel, line flow based state estimation (LFBSE) technique for power systems is presented in this paper. State variables are estimated through the constant, line flow based jacobian matrix constructed from the network equations. Unlike the conventional techniques where the outputs are the vectors of bus voltage magnitudes and angles, the results of the proposed method are in the terms of the quantities that indicate the line loadings and bus voltage magnitudes which can be used to identify the overloaded lines and limit violated buses instantaneously.

Reverse logistics has become a major component of extended producer’s responsibility. The dynamic nature of reverse logistics and the uncertainties within it demands more investigations on its variables. This paper elaborates the findings of a survey using factor analysis in investigations of factors influencing return handling of products in the form of parts and subassemblies. The Statistical Package for Social Sciences version 17 was used to analyze the effect of independent variables on key dependent variables.

Watershed management has increasingly been realized to be an essential component of rural development in many developing countries including India. However, studies related to the socio-economic implication of Watershed Management Programme (WMP) are often ambiguous. The present study assesses the impacts of WMP on livelihoods of the watershed community in an experimental watershed in the state of Karnataka, India, using Sustainable Livelihood Approach (SLA). This was accomplished with the help of Livelihood Assets Tracking (LAST) method which is based on SLA.

Over the last century numerous changes were brought to the internal combustion engines. Numerous researches are carried out in hopes of improving the engine characteristics. Increasing the efficiency and reducing the exhaust gases have been the dominant in the fields of research. The volume and number of applications of engines have grown steadily, penetrating and conquering new markets relentlessly. The exhaust gases contain numerous pollutants that are extremely harmful though in chronic conditions.

The electricity market has since 1980’s been gradually evolving from a monopoly market into a liberalized one for encouraging competition and improving efficiency. This introduces the opportunity for market participants (Power suppliers and consumers) to make more profit and benefits in the trading process of electrical energy. Therefore, it has become a core interest for the market participants to develop optimal bidding strategies to maximize the profit and benefits while participating in a competitive energy market.

In this paper, Gravitational Search Algorithm based optimal pitch controller design is proposed for an isolated wind-diesel hybrid power system. The Gravitational search algorithm (GSA) is one of the newest meta-heuristic searching algorithms, which is motivated by the Newton’s law of gravity and law of motion. The optimal controller parameters are obtained using Integral Square Error (ISE) criterion.  Simulation results show that the proposed Controller gives a superior dynamic performance and damps out the frequency deviation and attains the steady state value with less settling time.

This study aims to minimize the power loss in radial distribution networks which is realized by injecting reactive power with the aid of shunt capacitors installation at appropriate locations with optimal sizing.   A population based meta-heuristic search algorithm namely Harmony search optimization algorithm is utilized for finding out the optimal rating of shunt capacitors to be placed in the radial distribution networks. A Backward / Forward sweep based iterative power flow technique is adopted to compute the load flow solution.

This paper proposes an application of redox flow battery (RFB) for the improvement of Load Frequency Control (LFC) of a two-area interconnected hydro-nuclear power system using Artificial Bee Colony (ABC) optimization algorithm. The Redox Flow Battery, which is not aged due to the frequent charging and discharging, has a quick response and outstanding function during overload conditions. In addition to leveling load, the battery is advantageous for secondary control in the power system and maintenance of power quality of distributed power resources.

This paper presents an arbitrary switching hybrid pulse width modulation (ASHPWM) strategy for three level inverters. This hybrid-modulation strategy represents an amalgamation of fundamental-frequency modulation and sinusoidal pulse width modulation (SPWM) strategy and is designed for performance of the well-known carrier based modulation strategies. The main characteristic of this modulation is the reduction of switching losses with good harmonic performance, balanced power loss dissipation among the devices in the H- bridge inverter.

New recommendations and present standards have increased the interest in power factor correction circuits. Solid-state switch-mode converters have reached a matured level for improving power quality in terms of Power Factor Correction (PFC), reduced total harmonic distortion at input ac mains and precisely regulated dc output in buck, boost, buck–boost and multilevel modes with unidirectional and bidirectional power flow. In this paper, an improved power quality converter employing Zeta converter topology with conventional PI  is used to feed a Induction Motor (IM) drive.