Voltage constrained available transfer capability enhancement with FACTS devices

K. Narasimha Rao, J. Amarnath and K. Arun Kumar

The Available Transfer Capability (ATC) of a transmission system is a measure of unutilized capability of the system at a given time. The computation of ATC is very important to the transmission system security and market forecasting. While the power marketers are focusing on fully utilizing the transmission system, engineers are concern with the transmission system security as any power transfers over the limit might result in system instability. One of the most critical issues that any engineers would like to keep an eye on is the voltage collapse. Recent blackouts in major cities throughout the world have raised concerns about the voltage collapse phenomenon. FACTS devices such as thyristor controlled series compensators and thyristor controlled phase angle regulators, by controlling the power flows in the network, can help to reduce the flows in heavily loaded lines resulting in an increased loadability of the network and improves the voltage stability. This paper presents the aspects of enhancement of ATC limited by the voltage with and without contingency by simple and efficient models of FACTS devices. The effectiveness of the proposed methods is demonstrated on IEEE-14 bus and IEEE-30 bus system and the results are compared.

Simulation of D-Q control system for a unified power flow controller

S. Tara Kalyani and G. Tulasiram Das

The Unified Power Flow Controller (UPFC) is the most versatile and complex power electronic equipment that has emerged for the control and optimization of power flow in electrical power transmission system. This paper presents a control system which enables the UPFC to follow the changes in reference values like AC voltage and DC link voltage.  Operation of UPFC using a cross coupling control strategy which is based on d-q axis theory is presented by simulation. In this control system, the transformation of a three phase system to the d-q, 2-axis system is done through which real and reactive power can be controlled individually, while also regulating the local bus voltage. The performance of the proposed control system is checked by applying different faults across a transmission line to which UPFC is connected. A generalized pulse width modulation switching technique is used to generate firing pulses for both the converters of the UPFC. Simulations were carried out using PSCAD software to validate the performance of the UPFC connected to a transmission line with different faults. Simulation results show that the proposed control scheme is effective in damping the power swings in transient states.

Permutation and combinations approach to program evaluation and review technique

A. Prabhu Kumar, P. Ram Reddy and Ravindranath Tagore

The global market today is very competitive. Completion of projects on time and estimating the project completion time is still difficult in some areas like in the printing industry, where skill also plays a predominant role. The print production activities require human judgment and skill to accomplish the job. The raw materials properties used in the printing process influence runability of the printing machine. Controlling these factors in the production environment is very difficult. Estimating the stochastic job completion time by Program Evaluation and Review Technique (PERT) uses approximate calculation of standard deviation σ and the activity expected time Texp. The project scheduled time Tsch is greatly influenced by standard deviation. The most popular N-method of standard deviation adopted in calculating the Tsch in two conditions where Tmin and Tmax are closer to Tmaen and in extreme time estimate condition to Tmin and Tmax. Permutation and combinations of the Tmin, Tmean and Tmax are used to calculate Tsch of the project by a software developed for the purpose. The Tsch obtained in these three methods studied with the actual projects completion time over a period of time.

Statistical models for the errors in precipitation forecasts

Mario Lefebvre and Liliane Guilbault

We consider the problem of finding statistical models for the absolute value of the errors made by the Hydro-Québec company in their precipitation forecasts (based on the ones produced by Environment Canada) for the current day. We find that a generalised Pareto distribution provides a very good fit to the data. We also divide the data set into various cases, in particular the case when at least 10mm of rain (or water equivalent of snow) were forecasted.

On the steady state and dynamic characteristics of oil journal bearings with multiple axial grooves

L. Roy and P. L. Choudhury

The steady state and dynamic characteristics including whirl instability of journal bearings with three axial groove, one located at the top and another two 90 degrees clockwise and anticlockwise from the top, from which oil is supplied from one end of the bearing; a linear pressure drop is assumed in the groove and the steady state and dynamic characteristics are obtained theoretically. The Reynolds equation is solved numerically by finite difference method satisfying the appropriate boundary conditions. The dynamic behaviors in terms of stiffness and damping coefficients of fluid film and stability are found using a first-order perturbation method. It has been shown that both load capacity and stability improve for smaller groove angle is stability improved at higher eccentricity ratio.

Modeling of risk assessment for integrated project management system in construction

Amiruddin Ismail, Abbas M. Abd and Zamri Bin Chik

Abstract:

The experience and successful in the construction industry nowadays depends not only on the traditional civil engineering programs. Project management, over the last 25-30 years, has developed into a methodological and systematic way of dealing with all aspects of construction projects. The wide range of topics that are now representing the domain of construction management is more than emphasis on scheduling, cost control and resource management. They include, but are not limited to, engineering project management concepts, quality management system, environmental management system and techniques for analysis the potential success factors. This paper presents the results of a study carried out to identify some of the core issues in construction management which are mentioned above as a skeleton of integrated project management system for construction indus­try, and highlights the significance of studying several techniques to explain the strength and weakness for this knowledge area. It is planned that this study will continued to model the integrated project management system and develop an expert system  for purpose of education and training  to better equip middle and top level managers in the construction industry with the state-of-the-art tools, techniques and methodologies of project management.

Experimental investigation and modification in inking rollers of offset printing to achieve WCM approach in small and medium scale printing industries

Bhoomkar M. M., Likhite P. B. and Navale L. G.

Due to technology advancement and globalization policies technically perfect aesthetically attractive, quality products are available in the market. To meet expectations of quality the World Class Manufacturing (WCM) approach is need to be considered. In order to survive in the present global competition small and medium scale printing industries (SMPI) should also be world class, as it is directly related to advertising, packaging and newspaper industries. Printing is the process of uncertainty minute change in the process parameters like ink properties, paper quality, machine performance and operator skills may cause drastic variation in print quality. In this paper an attempt is made to experimentally investigate the trend of variation of print quality parameters to control the process variation and modification suggested in the machine to control the quality.

Optimized integral controller for economic load dispatch in a two area system based on Hooke-Jeeves algorithm

C. Srinivasa Rao, S. Siva Nagaraju, P. Sangameswara Raju and M. Rajender Reddy

Abstract:

The classical approach to the Economic Load Dispatch Problem (ELDP) seeks to minimize the cost of generation subject to the usual constraints. If the transmission losses are to be taken care of, a common method (λ-iteration procedure) involves adding the cost of transmission losses charged at incremental cost of received power to the cost of generation. Hooke-Jeeves method offers a suitable and robust approach to meet the objectives of optimizing the integral controller in order to obtain better response of the system. This paper presents an improved fast programming technique to optimize the value of integral controller in a two area reheat hydrothermal system and also implementing the concept of Economic load dispatch in a system consisting of ‘n’ generating units. Simulation results show that the generating units in each area take up the extra load as per their respective participation factors.

Optimal DG unit placement for loss reduction in radial distribution system-A case study

A. Lakshmi Devi and B. Subramanyam

Distributed generators are beneficial in reducing the losses effectively compared to other methods of loss reduction. In this paper optimal DG unit placement using fuzzy logic is discussed. The optimal size of the DG unit is calculated analytically using approximate reasoning suitable nodes are determined for DG unit placement. Voltage and power loss reduction indices of distribution system nodes are modeled by fuzzy membership functions. Fuzzy inference system containing a set of rules is used to determine the DG unit placement. DG units are placed with the highest suitability index. Simulation results show the advantage of optimal DG unit placement compared optimal capacitor unit placement. Compared to capacitor placement it is giving very good reduction not only in power loss but also it is improving voltage regulation.