Power quality issues have been a source of major concern in recent years due to extensive use of power electronic devices and non-linear loads in electrical power system. In power systems the common disturbances are voltage sags and swells, usually associated with power system faults. Therefore the effective detection of voltage sags and swells event is an important issue for both voltage sag a...

This study presents optimal placement of voltage sag monitors based on new Sag Occurrence Index (SOI) which ensures observability even in case of monitor failure or line outages. Multiple solutions for optimal placement of voltage sag monitors for voltage sag detection have been obtained by genetic algorithm approach such that observability of the whole system is guaranteed. A new Sag Occurrenc...

Voltage sag is the major power quality problem and receives wide attention. Although wavelet analysis works well for detecting voltage sag features, the existence of noise can reduce the advantages of wavelet method or even make it ineffective. To solve the problem, the paper uses multi-scale wavelet information by multiplying the results of several scales, and then searches the local maxima fr...

Abstract: Voltage sag is considered to be the most serious problem of power quality. It is caused by faults in the power system or by the starting of large induction motors. Voltage sag causes about 80% of the power quality problems in power systems. One of the main reasons for voltage sag is short circuit fault, which can be compensated for by a distribution static compensator (DSTATCOM) as an...

Author Affiliation: Department of Electrical Engineering, Indian Institute of Technology, Kanpur, India. Abstract: This letter presents a new method for the generation of reference voltage for a dynamic voltage restorer (DVR). These voltages, when injected in series with a distribution feeder by a voltage source inverter, can tightly regulate the voltage at the load terminal against imbalance o...

This paper reports concerns of capacitor placement in power distribution systems in the locality of a dynamic voltage restorer (DVR). A feedback controlled simulation model of an actual DVR is developed to perform case studies. Cogency of this model is established by associat ing the waveforms from the model with field measurements. Issues relating to expansion of a DVR in the locality of power...

We tested the hypothesis that constriction of descending vasa recta (DVR) is mediated by voltage-gated calcium entry. K(+) channel blockade with BaCl(2) (1 mM) or TEACl (30 mM) depolarized DVR smooth muscle/pericytes and constricted in vitro-perfused vessels. Pericyte depolarization by 100 mM extracellular KCl constricted DVR and increased pericyte intracellular Ca(2+) ([Ca(2+)](i)). The K(ATP)...

Power quality monitors (PQM) are required to be installed in a power supply network in order to assess power quality (PQ) disturbances such as voltage sags. However, with few PQMs installation, it is difficult to pinpoint the exact location of voltage sag. This paper proposes a new method for identifying the voltage sag source location by using the artificial neural network (ANN). Radial basis ...

Suitable voltage sag objectives are not yet found in any standard document. One of the reasons for the lack of objectives is the difficulty of defining suitable site sag indices. In this paper present sag characterisation methods are reviewed and discussed. The University of Wollongong sag index is summarized which shows a better way of characterizing voltage sags. A new method is then given fo...

This paper concentrates on the control of hybrid fuelcell (FC)/energystorage distributed generation (DG) systems under voltage sag in distribution systems. The proposed control strategy makes hybrid DG system work properly when a voltage disturbance occurs in distribution system, and it stays connected to the main grid. This controller determines the supercapacitor power that should be generate...