A number of impedance-based fault location algorithms have been developed for estimating the distance to faults in a transmission network. Each algorithm has specific input data requirements and makes certain assumptions that may or may not hold true in a particular fault location scenario. Without a detailed understanding of the principle of each fault-locating method, choosing the most suitable fault location algorithm can be a challenging task. This paper, therefore, presents the theory of one-ended (simple reactance, Takagi, modified Takagi, Eriksson, and Novosel et al.) and two-ended (synchronized, unsynchronized, and current-only) impedance-based fault location algorithms and demonstrates their application in locating realworld faults. The theory details the formulation and input data requirement of each fault-locating algorithm and evaluates the sensitivity of each to the following error sources: 1) load; 2) remote infeed; 3) fault resistance; 4) mutual coupling; 5) inaccurate line impedances; 6) DC offset and CT saturation; 7) threeterminal lines; and 8) tapped radial lines. From the theoretical analysis and field data testing, the following criteria are recommended for choosing the most suitable fault-locating algorithm: 1) data availability and 2) fault location application scenario. Another objective of this paper is to assess what additional information can be gleaned from waveforms recorded by intelligent electronic devices (IEDs) during a fault. Actual fault event data captured in utility networks is exploited to gain valuable feedback about the transmission network upstream from the IED device, and estimate the value of fault resistance.INDEX TERMS Fault location, impedance-measurement, intelligent electronic devices (IED), power system faults, power system reliability, transmission line measurements. NOMENCLATURE

Background:Vitiligo is an idiopathic acquired progressive de/hypopigmentary disorder of skin and mucosae. In Indian skin depigmentaion is very much obvious and can cause psychological distress, low self esteem and social stigmatization.Aims:The primary objective of this study was to evaluate the psychiatric morbidity in vitiligo patients and secondary objective was to assess the morbidity in all eight dimensions of psychosocial and physical aspects, i.e. cognitive, social, discomfort, limitations, depression, fear, embarrassment and anger.Materials and Methods:An institution based case-control study with sixty-one patients of vitiligo and equal number of healthy age and sex matched controls was undertaken. The self-reporting questionnaire-24 (SRQ-24) and skindex (A 61-item survey questionnaire) were used to assess the psychiatric morbidity in both the groups.Results:The SRQ-assessed psychiatric morbidity in the study group was 63.93%, compared with 24.59% in the control group (P<0.0001). Acral vitiligo had maximum association with psychiatric morbidity (86.67%) followed by vitiligo vulgaris (68%), mucosal vitiligo (62.5%) and others. According to the skindex, the most common psychiatric morbidity in vitiligo patients was depression (62.29%) followed by embarrassment (55.73%), social problem (54.09%), cognitive impairment (50.81%), physical limitation (47.54%), discomfort (40.98%), anger (36.06%) and fear (24.59%). The difference in Skindex scoring that marked the psychiatric morbidity among the case and control groups was statistically significant for depression, discomfort, social problem, cognitive impairment, embarrassment (P<0.0001) and physical limitation (P=0.0044).Conclusion:Vitiligo has a high degree of psychiatric morbidity.

Tower shadow and wind shear contribute to periodic fluctuations in electrical power output of a wind turbine generator. The frequency of the periodic fluctuations is n times the blade rotational frequency p, where n is the number of blades. For three-bladed wind turbines, this inherent characteristic is known as the 3p effect. In a weak-power system, it results in voltage fluctuation or flicker at the point of common coupling of the wind turbine to the grid. The phenomenon is important to model so as to evaluate the flicker magnitude at the design level. Hence, the paper aims to develop a detailed time-domain upwind fixed speed wind turbine model which includes the turbine's aerodynamic, mechanical, electrical, as well as tower shadow and wind shear components. The model allows users to input factors such as terrain, tower height, and tower diameter to calculate the 3p oscillations. The model can be expanded to suit studies involving variable speed wind turbines. Six case studies demonstrate how the model can be used for studying wind turbine interconnection and voltage flicker analysis. Results indicate that the model performs as expected.

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Traditional impedance-based fault-locating methods implemented in modern overcurrent protection relays require voltage and current measurements to provide reasonable fault-location estimates. Although they capture voltage and current, depending on field condition or due to equipment failure, relays may record current measurements only. Voltage measurements are thus missing or unavailable. The objective of this paper is to develop practical impedance-based fault-locating algorithms with current data (magnitude or phasors) as the only input and demonstrate the efficacy of the algorithms with simulated and actual field data. These algorithms use the circuit model of the distribution feeder and Kirchhoff's circuit laws in estimating the fault voltage at the relay location and then use impedance-based methods for fault location. Based on the analysis conducted on actual fault data, error in estimation is generally less than 0.5 mi from the actual location of the fault.Index Terms-Fault current, fault location, power distribution faults, power system faults, power system reliability.