Fault Discrimination Algorithm for Busbar Differential Protection Relaying Using Partial Operating Current Characteristics

Differential protection is the unit protection system which is applied to protect a particular unit of power systems. Unit is known as zone in protection terminology which is equivalent to simple electrical node. In recent time, low impedance current differential protection schemes based on percentage restrained characteristics are widely used in power systems to protect busbar systems. The main application issue of these schemes is mis-operation due to current transformer (CT) saturation during close-in external faults. Researchers have suggested various solution of this problem; however, individually they are not sufficient to puzzle out all mis-operational scenarios. This thesis presents a new bus differential algorithm by defining alternative partial operating current characteristics of a differential protection zone and investigating its performance for all practical bus faults. Mathematical model of partial operating current and operating principle of the proposed bus differential relay are described in details. A CT saturation detection algorithm which includes fast and late CT saturation detection techniques is incorporated in relay design to increase the sensitivity of partial operating current based internal-external fault discriminator for high impedance internal faults. Performance of the proposed relay is validated by an extensive test considering all possible fault scenarios

Fault Discrimination Algorithm for Busbar Differential Protection Relaying Using Partial Operating Current Characteristics

Differential protection is the unit protection system which is applied to protect a particular unit of power systems. Unit is known as zone in protection terminology which is equivalent to simple electrical node. In recent time, low impedance current differential protection schemes based on percentage restrained characteristics are widely used in power systems to protect busbar systems. The main application issue of these schemes is mis-operation due to current transformer (CT) saturation during close-in external faults. Researchers have suggested various solution of this problem; however, individually they are not sufficient to puzzle out all mis-operational scenarios. This thesis presents a new bus differential algorithm by defining alternative partial operating current characteristics of a differential protection zone and investigating its performance for all practical bus faults. Mathematical model of partial operating current and operating principle of the proposed bus differential relay are described in details. A CT saturation detection algorithm which includes fast and late CT saturation detection techniques is incorporated in relay design to increase the sensitivity of partial operating current based internal-external fault discriminator for high impedance internal faults. Performance of the proposed relay is validated by an extensive test considering all possible fault scenarios

Book Review- Is the American Century Over?

Review of: Joseph S. Nye, Jr., Is the American Century Over? (Global Futures Series), Cambridge and Massachusetts: Polity Press, 2015, 146 pp. + vi

Experimental Study On Thermal Performance And Visualization Of Loop Heat Pipe

Thermal management is an important issue for applications that generate high heat flux. Choosing an efficient cooling technique depends on thermal performance, reliability, manufacturing cost, and prospects for minimization. Based on these grounds, loop heat pipe (LHP) is a highly efficient two-phase passive cooling system used for cooling of electronics and many critical components of spacecraft and satellite. Loop Heat Pipe (LHP) uses capillary action to circulate cooling fluid inside the loop. Pressure developed in the pores of a wick provides the driving force to circulate the fluid. LHP has superior heat transport capability and can operate at any orientation. In the present study, a loop heat pipe with flat evaporator has been designed and manufactured and an experimental study was performed to investigate the effects of various parameters on loop performance. LHP was instrumented with thermocouples to measure the loop temperature at various positions. Temperature oscillations have been observed at the startup of LHP. Performance of LHP has been evaluated at a wide range of evaporator heat loads. In order to comprehend the complex phenomenon inside LHP, the main structure of LHP has been made from transparent acrylic plastic to visualize the evaporation and the condensation process. A high-speed video camera has been utilized to visualize the operational process. Data collected from the experiment provides a significant insight into the physics of LHP operation. An analysis is presented to explain the startup process. Understanding of startup process is necessary for predicting the performance of LHP

Multivariate Outlier Mining Using Cluster Analysis: Case Study - National Health Interview Survey

Outlier mining is a fundamental issue in many statistical analyses, especially in multivariate cases. Outliers may exert undue influence on outcomes of the analysis. In most cases, it is a big challenge to reveal the pattern of the outliers and the outlyingness . There are several approaches and methods to detect anomalous data points in data. But no single method is perfect for every data set especially when the data dimension and volume is high. In this thesis, I review distance-based clustering methods for multivariate outlier mining and demonstrate the usefulness of it in a medical setting. Specifically, I discuss Hierarchical clustering and the multivariate methods of determining appropriate cluster(s). After mining the multivariate outliers, I examine and describe the characteristics of the variables for those outliers. Finally, I demonstrate the application of these methods using the National Health Interview Survey (NHIS) 2008 database for the purposes of studying adolescent obesity

Japanese foreign direct investment (FDI) in South Asia : necessity and rationale for an evolving new role shouldered by multinational corporations (MNCs) in the challenging epoch of globalization

制度:新 ; 文部省報告番号:甲2303号 ; 学位の種類:博士(学術) ; 授与年月日:2007-03-15 ; 早大学位記番号:新4363早稲田大

Cross-Correlation-Based Fisheries Stock Assessment Technique: Utilization of Standard Deviation of Cross-Correlation Function as Estimation Parameter with Four Acoustic Sensors

In the past, cross-correlation-based fisheries stock assessment technique utilized the mean and the ratio of standard deviation to the mean of cross-correlation function (CCF) as estimation parameter. However, in this paper, we have utilized only standard deviation of CCF as estimation parameter to estimate the population size. We utilized four acoustic sensors and considered chirp sound which is commonly generated by damselfish (Dascyllus aruanus), humpback whales (Megaptera novaeangliae), dugongs (Dugong dugon), etc., species to accomplish the simulations. We found that a robust estimation can be obtained using standard deviation of CCF as estimation parameter even when the distances between acoustic sensors are small