Journal Volume 14 Issue 1

Harmonic Domain Modelling of Transformer Core Nonlinearities Using the DIgSILENT PowerFactory Software

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Wojciech Wiechowski, Birgitte Bak-Jensen, Claus Leth Bak, Jan Lykkegaard

This paper demonstrates the results of implementation and verification of an already existing algorithm that allows for calculating saturation characteristics of singlephase power transformers. The algorithm was described for the first time in 1993. Now this algorithm has been implemented using the DIgSILENT Programming Language (DPL) as an external script in the harmonic domain calculations of a power system analysis tool PowerFactory [10]. The algorithm is verified by harmonic measurements on a single-phase power transformer.

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Hybrid UPS Based on Supercapacitor Energy Storage and Adjustable Speed Generator

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Zdzislaw Chlodnicki, Wlodzimierz Koczara, Nazar Al-Khayat

This paper presents a hybrid on-line UPS system (H-UPS). The system is based on an on-line (double conversion) UPS, consisting of two controlled energy storage systems. The first one is a static energy storage system based on supercapacitor bank. The second energy source is adjustable speed generating system supplying DC link voltage. A control concept of the UPS operation, according short and long failure of the supply utility voltage is developed. The 5 kW H-UPS is designed, built and tested.

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Voltage Sag Source Location Based on Voltage Measurements Only

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Roberto Chouhy Leborgne, Daniel Karlsson

This paper introduces an alternative method for voltage sag source location based on voltage information only. The source is located considering the sag magnitude at the primary and secondary side of a transformer. A comprehensive review of previously proposed methods based on voltage and current measurements is presented. The performance of the proposed method is compared with the previous ones using PSCAD /EM TDC on a model of a regional network including transmission and sub-transmission levels.

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Computer-Based Voltage Dip Assessment in Transmission and Distribution Networks

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Juan A. Martinez-Velasco

Digital simulation is a powerful mean to predict the voltage dip performance of a power network. Voltage dip characteristics can be accurately reproduced using present simulation tools and a stochastic prediction procedure that could incorporate the random nature of the voltage dip causes and the behaviour of sensitive equipment during this type of events. This work is aimed at providing a review of techniques that can be applied to voltage dip prediction, assuming that voltage dips are caused by faults.

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Voltage quality improvement using DVR

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Chellali Benachaiba, Brahim Ferdi

The problem of voltage sags and Swells and its severe impact on sensitive loads is well known. To solve this problem, custom power devices are used. One of those devices is the Dynamic Voltage Restorer (DVR), which is the most efficient and effective modern custom power device used in power distribution networks. Its appeal includes lower cost, smaller size, and its fast dynamic response to the disturbance. This paper describes DVR principles and voltage restoration methods at the point of common coupling (PCC ).

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Transfiguration of supplied-by-HV/MV transformer network to the supply radius

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Stanisław Czepiel

A HV/MV transformer supplies a few power lines of known parameters and loads. These power lines can be substituted with the supply radius, at the end of which there is the equivalent load-receiver representing the entire load being transmitted by the transformer. The R and X parameters of this substitute supply radius are needed to calculate adjusting parameters of the voltage regulator which controls the HV/MV transformer. The presented method enables simple determining of the supply radius parameters R and X.

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Effects of Source Voltage Harmonics on Power Factor Compensation in AC Chopper Circuits

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M. Erhan Balci, M. Hakan Hocaoglu

In recent years, the detailed modelling of power electronic devices and their behaviours on various system conditions are a great concern of the power industries and customers. One of the widely proliferated such devices is the triac controlled ac choppers. Although these types of devices have important application areas, their poor power factor is the main obstacle for the large scale implementation in power systems.

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Fuzzy System for the Detection of Power Quality Performance on Induction Motor

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M.S. Ballal, D.M. Ballal, H.M. Suryawanshi

Sensitive equipment and non-linear loads are now more common in both the industrial/commercial sectors and the domestic environment. Because of this a heightened awareness of power quality is developing amongst electricity users. Therefore, power quality is an issue that is becoming increasingly important to electricity consumers at all levels of usage. This article presents the fuzzy system to determine the power quality. The performance of three-phase induction motor is observed for different power quality conditions in laboratory.

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A New Closed Loop Speed Control Strategy for a Vector Controlled Three- Phase Induction Motor Drive

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Anurag Tripathi, Arunima Dey, Bharti Dwivedi, Bhim Singh, Dinesh Chandra

This paper presents a completely mathematical equations based model on control of torque and speed of a three-phase indirect vector controlled VSI fed cage induction motor drive that is controlled through the space vector modulated method. This enables a wide range of acceptability of the model for various values of load and for various types and ratings of induction motors. The uniqueness of the model lies in the fact that the deviations in the torque and speed on sudden application of reference step change in speed values are minimum i.e.

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An Improved Model of a Three phase Induction Motor Incorporating the Parameter Variations

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Arunima Dey, Anurag Tripathi, Bhim Singh, Bharti Dwivedi, Dinesh Chandra

A great deal of work is being done on the betterment of control through simulation of the electric drives used for various high-power purposes. The authenticity of the simulated results is based on the accurate modeling of the various parts of the electric drive system. Three–phase Induction motors form an extremely important part of the modern day electric drive system and their usage is continuously on a rise owing to their inherent properties of ruggedness, minimum maintenance requirements and continually increasing efficiencies.

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