• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1371-1379
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• 2013

Application of induction machines in wind turbine driven generators is a good alternative due to their good characteristics such as efficiency, reliability and low cost. Nevertheless, when isolated operation is required, the application of external capacitive bank, connected to the stator windings, to provide self-excitation results in a rather complex analysis. This paper presents an analysis of self-excited induction generator connected to a load either directly or by an intermediate of a power converter. At first a dynamic model of the induction generator accounting for magnetic saturation is developed. Then a number of balanced and unbalanced capacitors, passive and active loads are verified. Experimental results obtained from laboratory tests are compared to those simulated; the two are shown to be in good agreement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1174-1176
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• 2000

This paper presents a new control strategy of the active power filter to compensate the fundamental and high order reactive power. Using the proposed control strategy, the calculation of active and reactive power of the load is not required. So the system configurations and the controller can be constructed very simply. To decrease the load of active power filter, the LC passive filter bank can be used without any additional strategy. In this paper, the algorithm of the proposed new control strategy is discussed and the experimental results are shown.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 추계학술대회 논문집
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• pp.54-56
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• 2008

본 논문은 연료전지 발전출력을 이용해서 정전 시에도 연속적으로 부하에 전력을 공급하기 위한 백업 시스템을 구성하는데 있어 필요한 보상장치를 제안한다. 보상장치는 삼상 PWM 정류기와 Load Bank로 구성되어 있으며 다음과 같은 기능을 수행한다. 첫째, 보상전력에 해당하는 유효전력을 소비하는 역할을 한다. 둘째, 부하에서 발생하는 무효전력을 보상해서 역률을 개선하는 기능을 수행한다. 셋째, 삼상부하에서 언밸런스가 발생할 때 역상분 유효 또는 무효전력에 해당하는 성분을 보상하는 역할을 수행한다. 넷째, 비선형 부하에서 발생하는 고조파를 보상하는 역할을 수행한다. 상기 기능을 수행하기 위한 제어알고리즘을 제안한다. 본 논문에서 제안한 보상장치의 우수성을 시뮬레이션을 통해 검증하였다.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1511-1518
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• 2017

Renewable energy hybrid systems look into the process of choosing the finest arrangement of components and their sizing with suitable operation approach to deliver effective, consistent and cost effective energy source. This paper presents hybrid renewable energy system (HRES) solar photovoltaic, downdraft biomass gasifier, and fuel cell based generation system. HRES electrical power to supply the electrical load demand of academic research building sited in $23^{\circ}12^{\prime}N$ latitude and $77^{\circ}24^{\prime}E$ longitude, India. Fuzzy logic programming discover the most effective capital and replacement value on components of HRES. The cause regarding fuzzy logic rule usage on HOMER pro (Hybrid optimization model for multiple energy resources) software program finds the optimum performance of HRES. HRES is designed as well as simulated to average energy demand 56.52 kWh/day with a peak energy demand 4.4 kW. The results shows the fuel cell and battery bank are the most significant modules of the HRES to meet load demand at late night and early morning hours. The total power generation of HRES is 23,794 kWh/year to the supply of the load demand is 20,631 kWh/year with 0% capacity shortage.

• 한국환경과학회지
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• 제9권1호
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• pp.35-42
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• 2000

In this study, the movable bed model testing was carried out so as to analyze bed profile changes including predicting scouring and deposition of bed profile and to solve hydraulic problems affecting with bed and both-bank between upstream and downstream of intake weir in the Nakdong river channel. The movable bed model testing consists of fundamental test, movable model test and numerical analysis method respectively. The fundamental test was enforced to analyze relationship of discharge and sediment load in the tilting flume. When the movable model test was worked, it was shown that sediment budget between input sediment load and output sediment load was balanced exactly. As a result of movable model test, it was presented that scouring and deposition changes in quantities between the upstream and downstream of modification weir were less than those of nature and planning weir. Finally, numerical analysis method was operated by 1-dimensional bed profile changes model ; HEC-6 model so as to complement unsolving hard problems during movable model test. So, modification weir will sustained the stable bed profile changes than any other weirs in the study channel.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1454-1470
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• 2014

This paper propose a new power conditioner topology with intelligent power management controller that integrates multiple renewable energy sources such as solar energy, wind energy and fuel cell energy with battery backup to make best use of their operating characteristics and obtain better reliability than that could be obtained by single renewable energy based power supply. The proposed embedded controller is programmed for maintaining a constant voltage at PCC, maximum power point tracking for solar PV panel and WTG and power flow control by regulating the reference currents of the controller on instantaneous basis based on the power delivered by the sources and load demand. Instantaneous variation in reference currents of the controller enhances the controller response as it accommodates the effect of continuously varying solar insolation and wind speed in the power management. The power conditioner uses a battery bank with embedded controller based online SOC estimation and battery charging system to suitably sink or source the input power based on the load demand. The simulation results of the proposed power management system for a standalone solar/WTG/fuel cell fed hybrid power supply with real time solar radiation and wind velocity data collected from solar centre, KEC for a sporadically varying load demand is presented in this paper and the results are encouraging in reliability and stability perspective.

• 조명전기설비학회논문지
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• 제19권5호
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• pp.23-29
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• 2005

비선형 부하의 증가는 변압기에 고조파 전류를 증가시키는 요인이 되고 있다. 변압기에 고조파 전류가 유입되면 손실이 증가되고, 변압기 출력이 감소되어야 한다. 본 논문에서는 고조파를 고려한 부하의 변압기 용량 산정법을 제시하고, 직렬리액터가 연결된 커패시터 뱅크와 고조파 필터의 적용으로 변압기 출력을 증가시킬 수 있음을 검증하였다. 사례연구의 시뮬레이션은 EDSA 프로그램을 사용하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.414-418
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• 2005

A finite element model is developed for the numerical simulation of bed elevation change in a curved channel. The SU/PG (Streamline-Upwind/Petrov-Galerkin) method is used to solve 2D shallow water equations and the BG (Bubnov-Galerkin) method is used for the Exner equation. For the time derivative terms, the Crank-Nicolson scheme is used. The developed model is a decoupled model in a sense that the bed elevation does not change simultaneously with the flow during the computational time step. The total load formula with is used for the sediment transport model. The slip conditions are described along the lateral boundaries. The effects of gravity force due to geometry change and the secondary flows in a curved channel are considered in the model. For the verification, the model is applied to two laboratory experiments. The first is $140^{\circ}$ bended channel data at Delft Hydraulics Laboratory and the second is $140^{\circ}$ bended channel data at Laboratory of Fluid Mechanics of the Delft University of Technology. The finite element grid is constructed with linear quadrilateral elements. It is found that the computed results are in good agreement with measured data, showing a point bar at the inner bank and a pool at the outer bank.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.399-402
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• 2003

In this paper, the on line volt/var control algorithms of the food Load Tap Changer (LTC) transformer and Shunt Capacitor(SC) are proposed for distribution volt/var regulation. In the existing volt/var control of the distribution substation, the voltage of feeders and var of distribution systems is mainly controlled by the LTC transformer tap position and on/off status of the shunt capacitor. The LTC and shunt capacitor bank has discrete operation characteristics and therefore it is very difficult to control volt/var at the distribution networks within the satisfactory levels. Also there is limitation of the operation times of the LTC and shunt capacitor bank because it is affects on their functional lifetime. The proposed volt/var control algorithm determine an optimal tap position of LTC and on/off status of shunt capacitors at a distribution network with the multiple feeders. The mathematical equations of the proposed method are introduced. Simple case study was performed to verify the effectiveness of the proposed method.

• Journal of Power Electronics
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• 제5권4호
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• pp.289-304
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• 2005

This paper describes a simple control structure and power conditioning system for an indirect vector controlled stand-alone induction generator (IG) used to operate under variable speed. The required reactive power for the IG system is supplied by means of a capacitor bank and a voltage-source PWM converter. Using a capacitor bank to transfer the reactive power to the IG under the rated speed and no-load conditions starts the IG operation and reduces the PWM converter size. The vector control structure for the variable speed IG power conditioning system compensates for changes in the electrical three-phase and DC loads while considering the magnetizing curve of the IG. The vector control structure is developed to regulate the DC link voltage of the PWM converter and the IG output voltage. The experimental and simulated performance results of the IG power conditioning system at various speeds and loads are given and show that this proposed scheme can be used efficiently for a variable speed, wind energy conversion system.