• Journal of Power Electronics
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• 제12권5호
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• pp.821-829
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• 2012

This research article presents a novel approach based on an instantaneous active and reactive power component (p-q) theory for generating reference currents for shunt active filter (SHAF). Three-phase reference current waveforms generated by proposed scheme are tracked by the three-phase voltage source converter in a hysteresis band control scheme. The performance of the SHAF using the p-q control strategy has been evaluated under various source conditions. The performance of the proposed control strategy has been evaluated in terms of harmonic mitigation and DC link voltage regulation. In order to maintain DC link voltage constant and to generate the compensating reference currents, we have developed Fuzzy logic controller with different (Trapezoidal, Triangular and Gaussian) fuzzy M.F.s. The proposed SHAF with different fuzzy M.F.s is able to eliminate the uncertainty in the system and SHAF gains outstanding compensation abilities. The detailed simulation results using MATLAB/SIMULINK software are presented to support the feasibility of proposed control strategy. To validate the proposed approach, the system is also implemented on a real time digital simulator and adequate results are reported for its verifications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.156-158
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• 1998

This paper presents parallel operation of two 3-phase PWM converters whose Power and control schemes can be directly applied to a large capacity system. This paper describes power circuit, dc voltage regulation, input power factor correction and balancing load control of two converters. Switching device Is IGBT and CPU of control is 32-bit floating point DSP for real time instantaneous control. Simulations and experimental results for 20kw model conform the validity of proposed schemes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.374-376
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• 2001

FACTS technology is developed into the sophisticated system technology which combines conventional power system technology with power electronics, micro-process control, and information technology. Its objectives are achieving enhancement of the power system flexibility and maximum utilization of the power transfer capability through improvements of the system reliability, controllability, and efficiency[1]. As a series and shunt compensator, UPFC consists of two inverters with common dc link capacitor bank. It controls the magnitude of shunt bus voltage and real and reactive power flow of transmission line[2]. In this paper, we present the design and control algorithm of UPFC simulator for KERI simulator. As a control algorithm is implemented by digital controller, we consider sample-and-hold of signals In this simulation, we use EMTDC/PSCAD V3.0 software which can simulate instantaneous voltage and current.

• 한국통신학회논문지
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• 제34권8C호
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• pp.756-763
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• 2009

LMS알고리즘은 잡음이 섞인 신호로부터 원 신호를 복원하는데 자주 사용된다. 이 LMS알고리즘의 주된 결점은 음성 신호 파워에 따라 선형적으로 EMSE(Excess Mean Square Error)가 증가한다. 그 결과 최적의 값에서 큰 EMSE 때문에 성능의 효율성이 떨어진다. 이러한 결점은 적은 스텝사이즈를 선택함으로서 해결 할 수 있지만, 수렴율이 늦어지는 단점이 있어, 빠른 수렴율과 낮은 EMSE를 동시에 만족할 수 있는 값이 필요하다. 본 논문에서는 IGC(lnstantaneous Gain Control) 알고리즘을 음성신호가 존재하는 경우에서 제안한다. 시뮬레이션은 음성신호와 가우시안 잡음을 이용하여 수행하였고, 수렴율, 잡음제거, 그리고 EMSE에서 LMS알고리즘보다 IGC알고리즘이 우수하다는 것을 보인다.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1156-1165
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• 2018

This paper presents a detailed realization of direct torque controlled induction motor drive for elevator applications. The drive is controlled according to the well-known space vector modulated direct control scheme (SVM-DTC). As the elevator drives are usually equipped with speed sensors, flux estimation is carried out using a current model where two stator currents are measured and accurate instantaneous rotor speed measurement is used to overcome the need for measuring stator voltages. Speed profiling for a comfortable elevator ride and other supervisory control activities to provide smooth operation are also explained. The drive performance is examined and controllers' parameters are fine-tuned using MATLAB/SIMULINK. The blocks used for flux and torque estimation and control in the offline simulation are compiled for real-time using dSPACE Microlabox. The performance of the drive has been verified experimentally. The results show good performance under transient and steady state conditions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 학술대회 논문집 전문대학교육위원
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• pp.162-166
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• 2000

In this paper, a maximum efficiency control technique of real-time processing in which parameter variation is compensated in vector control of an induction motors(I.M.) is proposed. Based on equivalent model of I.M., a loss minimization factor(LMF) with the variations of speed is derived. To solve problem of inaccuracy of LMF curves due to machine parameter variation, rotor resistance estimation is performed by using instantaneous reactive power. The estimated rotor resistance values are applied to the maximum efficiency control with a LMF.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2016년도 전력전자학술대회 논문집
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• pp.99-100
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• 2016

In a AC motor used by three phase inverter, the phase current must be measured to control instantaneous torque. It is expensive to use current sensor for measuring current in low cost motor. So, shunt resistor is used to measure current. But, the method sensing the phase current using shunt resistor cannot perform the vector control in high speed because of the area that impossible to restore three phase current. In this paper, predictive current is proposed for reconstructing the current in the impossible current sensing area that reduce the current ripple in TSSI(Three shunt sensing inverter) for PMSM.

• Journal of Electrical Engineering and Technology
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• 제5권1호
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• pp.116-128
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• 2010

Modeling of the three phase electric arc furnace and its voltage flicker mitigation are the purposes of this paper. For modeling of the electric arc furnace, at first, the arc is modeled by using current-voltage characteristic of a real arc. Then, the arc random characteristic has been taken into account by modulating the ac voltage via a band limited white noise. The electric arc furnace compensation with static VAr compensator, Thyristor Controlled Reactor combined with a Fixed Capacitor bank (TCR/FC), is discussed for closed loop control of the compensator. Instantaneous flicker sensation curves, before and after accomplishing compensation, are measured based on IEC standard. A new method for controlling TCR/FC compensator is proposed. This method is based on applying a predictive approach with closed loop control of the TCR/FC. In this method, by using the previous samples of the load reactive power, the future values of the load reactive power are predicted in order to consider the time delay in the compensator control. Also, in closed loop control, two different approaches are considered. The former is based on voltage regulation at the point of common coupling (PCC) and the later is based on enhancement of power factor at PCC. Finally, in order to show the effectiveness of the proposed methodology, the simulation results are provided.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.505-508
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• 1994

This paper describes an implementation of a single phase PWM ac/dc converter whose control scheme can be directly applied to the rectification of ac traction system. Power circuit using self-commutated switching devices(GTO) provides input power factor correction with dc voltage regulation. Effective compensation of load variations and line disturbance can be accomplished by real time instantaneous control of ac input current and dc link voltage using 32 bit floating point DSP. Parallel operation of two converters reduces the input line current ripple. Experimental results of the two parallel converter system are shown in the 20KW range for the verification of the system.

• 한국통신학회논문지
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• 제40권10호
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• pp.2006-2013
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• 2015

본 논문에서는 저전력 무선통신 기반 다중 프로토콜 게이트웨이 시스템 설계를 제안한다. 제안 된 멀티 프로토콜 게이트웨이 시스템은 가로등 전력 제어 및 환경 모니터링을 위한 정보를 수집하여 무선 네트워크와 유선 네트워크를 통해 현장 상황을 실시간으로 모니터링 및 제어 할 수 있도록 설계하였다. 코드분할 다중접속 및 이더넷, 위성 항법장치, 저전력 무선통신 등의 유선 또는 무선통신을 선택적으로 사용한 복합처리와 함께 다중 센서를 이용하여 수집 된 데이터를 저전력 무선통신을 통해 서버로 전송하는 중개 역할을 하도록 설계하였다. 그리고 유지보수 비용 및 하드웨어 교체 용이성을 위해 CPU 및 베이스 보드로 분리하여 설계하였다. 본 논문에서 제안된 다중 프로토콜 게이트웨이 시스템의 전원, 충격, 연속동작 신뢰성 검증결과, 95% 이상의 정상동작 성공률 및 정상적인 연속동작 결과를 얻을 수 있었다. 그리고 전압 강하 및 순간 내성시험, 전도성 RF 전자기장 내성시험에서 평균 A등급의 평가결과를 얻을 수 있었다.