• Journal of international Conference on Electrical Machines and Systems
• /
• v.2 no.4
• /
• pp.491-497
• /
• 2013

This paper introduces the high efficiency operation of switched reluctance generator (SRG). The proposed SRG operates under the rated speed. The high efficiency can be obtained by the optimal current shape which can make the total losses minimum. For this purpose, theoretical analysis of the copper and core loss is done. In addition, a modified angle position control (MAPC) method which can get the optimal current shape over wide speed condition is presented. In order to verity the theory, the experimental platform is set up. The feasibility of the theory is verified by the simulation and experimental results. The proposed method is simple, reliable and easy to achieve.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.9
• /
• pp.461-466
• /
• 2005

This paper addresses the bidding strategies of a hydro generator in an electricity market, and their effect on the electricity market in accordance with some parameters: the water volume, the demand elasticity, and the hydro unit performance. The competition of a hydro generator is formulated as a hi-level optimization problem, and the solving scheme for the equilibrium condition is proposed as a set of nonlinear simultaneous equations. The equilibrium of the oligopolistic model is evaluated by comparison with that of a perfect competition model from the viewpoint of a market power. Simulation results show some parameters have an influence on the market power of an electricity market including a hydro generator.

• Journal of Power Electronics
• /
• v.8 no.1
• /
• pp.81-90
• /
• 2008

This paper presents an investigation of a voltage and frequency controller for an isolated asynchronous generator (IAG) driven. by a wind turbine and supplying 3-phase 4-wire loads to the isolated areas where a grid is not accessible. The control strategy is based on the indirect current control of the VSC (voltage source converter) using the frequency PI controller. The proposed controller consists of three single-phase IGBT (Insulated Gate Bipolar Junction Transistor) based VSC, which are connected to each phase of the IAG through three single phase transformers and a battery at their DC link. The controller has the capability of controlling reactive and active powers to regulate the magnitude and frequency of the generated voltage, harmonic elimination, load balancing and neutral current compensation. The proposed isolated system is modeled and simulated in MATLAB using Simulink and PSB (Power System Block-set) toolboxes to verify the performance of the controller.

• MALSORI
• /
• no.48
• /
• pp.57-67
• /
• 2003

This paper presents a systematic description of exceptional pronunciations for automatic Korean pronunciation generation. An automatic pronunciation generator in Korean is an essential part of a Korean speech recognition system and a TTS (Text-To-Speech) system. It is composed of a set of regular rules and an exceptional pronunciation dictionary. The exceptional pronunciation dictionary is created by extracting the words that have exceptional pronunciations, based on the characteristics of the words of exceptional pronunciation through phonological research and the systematic analysis of the entries of Korean dictionaries. Thus, the method contributes to improve performance of automatic pronunciation generator in Korean as well as the performance of speech recognition system and TTS system in Korean.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.2
• /
• pp.595-602
• /
• 2015

The rotor configuration of the brushless doubly fed induction generator (BDFIG) plays an important role in its performance. In order to make the magnetomotive force (MMF) space vector in one set rotor windings to couple both magnetic fields with different pole-pair and have low resistance and inductance, this paper presents a novel wound rotor type for BDFIG with low space harmonic contents. In accordance with the principles of slot MMF harmonics and unequal element coils, this novel rotor winding is designed to be composed of three-layer unequal-pitch unequal-turn coils. The optimal design process and rules are given in detail with an example. The performance of a 700kW 2/4 pole-pair prototype with the proposed wound rotor is analyzed by the finite element simulation and experimental test, which are also carried out to verify the effectiveness of the proposed wound rotor configuration.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.28 no.3
• /
• pp.263-272
• /
• 2008

Many technical methods are used for nondestructive testing field for solid materials. Among those, ultrasonic inspection methods are widely used and one of the popular methods involves the extraction of an appropriate set of features followed by the use of a neural network for the classification of the signals in the feature space. This paper describes an approach which uses LMS method to determine the coordinates of the ultrasonic probe followed by the use of SAFT with centroid technique to estimate the location of the ultrasonic reflector. The method is employed for classifying UT-NDE signals from the steam generator tubes in a nuclear power plant. The classification results are presented for the ultrasonic signals from cracks and deposits within steam generator tubes.

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.223-226
• /
• 1998

The control objective of steam generator water level in the secondary circuit of a nuclear power plant is to regulate the water level at the desired set point. The dynamics of steam generators is non-linear in nature. The task of modelling such plant is very difficult and especially so when plant operating conditions change frequently. In these reasons, conventional PI gains over all pover range will not work efficiently and a manual control is generally used in low power operation. Therefore the robust H$\infty$ controller design method should be required. In this paper, we design the robust H$\infty$ controller for water level control of steam generator using a mixed H$\infty$ optimization with model-matching method. Firstly we choose the desired model that has good disturbance rejection performance. Secondly we design a stabilizing controller to keep the model-matching error small and also provide sufficiently large stability margin against additive perturbations of the nominal plant.

• Proceedings of the KIEE Conference
• /
• 2001.05a
• /
• pp.166-168
• /
• 2001

Generation by the privately owned generators, which are normally operated has occupied about 10% of total generation. Recently the small co-generation employed gas engine has been introduced and attracted public interest. For privately owned generator to be paralleled Utilities, a customer complies with Generator Parallel Operation Guideline set by Utilities and installs related protective relays. But the guideline is not specified to small co-generation, only provides parallel operation of privately owned generator. So applying this guideline, initial investment can be too high comparing to total co-generation cost. Besides there is no specified guide about ALTS, which arises asynchronous problem. In this paper we analyzed guideline and technical problem when small co-generation is paralleled. And additionally needed researching area to improve distribution of small co-generation is discussed.

• Proceedings of the KIEE Conference
• /
• 2005.10b
• /
• pp.328-330
• /
• 2005

Most of the water level controllers of the actual plant are PID controllers. But they have limitations in appling for tracking the set point and getting rid of disturbances, so there are some defects to apply in the actual ground even though many research works represented the resolution to solve it. In this paper, we design a fuzzy logic system (FLS) for controlling the steam generator water level in nuclear power plants. Some computer simulations reveal similar performance with the conventional PID controller.

• Proceedings of the KWS Conference
• /
• 2004.05a
• /
• pp.305-307
• /
• 2004

One set of rotor coils is required per each large generator rotor assembly, Rotors consist of two directly opposing poles. Each pole requires from 5 to 9 coils. Each coil is made up of two halves identified on the connection end. These coil halves will be joined together by butt brazing process during subsequent rotor assembly. Each half coil is made up of typically 4 to 9 layers of copper conductors. Because of Generator rotor is rotated very high speed with 3,600RPM, the quality soundness of brazed joints is very important at each coil. But, it is very difficult to be optimized non-destructive evaluation, because c-coil has the long shape and evaluation is to be done assembled condition. In this paper introduce newly developed inspection process and acceptance standards for the ultrasonic inspection of " C" coil butt braze. This inspection system is a semi-automatic ultrasonic flaw detector with data acquisition and retention capable of assessing the relative lack of bond of brazed butt joints