• 한국정밀공학회지
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• 제28권4호
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• pp.455-462
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• 2011

This paper is about the design of a new gravity compensator for the lower body exo-skeleton device. The exo-skeleton devices is for increasing the torque of the human body joint for the purpose of helping the disabled, workers in the industry, and military soldiers. So far, most of studied exo-skeleton devices are actuated by the motors, but motors are limited in energy such that a short durability is always a big problem. In this paper, a new gravity compensator is proposed to reduce the torque load applied to human body joints due to gravity. The gravity compensator is designed using a tortional bar spring, and its structure and characteristics are studied through the test and computer simulation. A design concept on the exo-skeleton device using the gravity compensator is presented. An analysis and computer simulation on the torque reduction of the proposed exo-skeleton device that applies and non-applies the gravity compensator are performed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.780-784
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• 1998

A novel active input unbalance voltage compensator with harmonic current compensating capability is proposed and the operating principle of the proposed system is presented in the 3-phase power system. The proposed system performs both the voltage regulation of the load and the compensation of the harmonic currents generated due to nonlinear load such as diode rectifier. The system to compensate unbalanced voltage and hramonic currents is composed of a 3-phase voltage source inverter, LC filter, series transformer and passive devices at the load side of the line. The compensating voltage to regulate the load voltage and to remove the harmonic current components is transmitted to the line by the series transformer. The validity of the line by the series transformer. The validity of the proposed system is proved by the results of computer simulation.

• 전기전자학회논문지
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• 제23권1호
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• pp.99-106
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• 2019

본 논문에서는 UPQC 시스템과 SVC를 결합한 새로운 형태의 보상장치를 제안하고자 한다. 기존의 UPQC는 직렬형 인버터, 병렬형 인버터, DC 링크로 구성되어 있어있으며 우수한 전력품질 보상 성능을 보이지만 높은 인버터 정격을 요구한다. 제안된 방식은 직렬형 인버터, 병렬형 인버터와 DC 링크 그리고 병렬형 인버터의 출력단에 결합된 SVC로 구성되어 있으며, 기존 UPQC에 비해 넓은 무효전력 보상 범위와 낮은 DC 링크 전압의 장점을 가지고 있다. 또한, SVC가 결합된 새로운 UPQC의 구성은 Matlab 시뮬레이션을 통해 성능을 검증하였다.

• 조명전기설비학회논문지
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• 제21권5호
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• pp.82-89
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• 2007

여자제어 시스템의 AVR(Automatic Voltage Regulator) 장치는 발전기의 출력 전압을 일정하게 유지시키기 위하여, 여자기의 전압 또는 전류를 발전기 부하 전류 및 전압 변동에 따라 제어하는 역할을 수행한다. 이러한 AVR 장치의 응답성과 제어 특성은 발전기의 부하 변동 또는 과도 응답 상태에서의 출력 특성을 결정하게 된다. 본 논문에서는 고성능 전동기 제어 시스템에 널리 사용되고 있는 PWM 제어 시스템과 부하 변동에 강인하게 동작할 수 있는 과도 응답 보상기를 적용한 고성능 여자 시스템을 제안한다. 과도 응답 보상기는 발전기의 부하 전류 변동에 따라, 여자기의 제어신호를 PID 제어기의 출력에 더하여 빠른 속응성과 안정성을 가지도록 함으로써, 발전기의 출력 전압을 안정적으로 공급할 수 있도록 제어한다. 제안된 고성능 여자 시스템은 컴퓨터 시뮬레이션과 소형 발전기 시스템에 적용된 실험을 통하여 그 성능을 검증하였다.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권4호
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• pp.447-453
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• 2013

Compensating characteristics of a voltage sag/swell compensator utilizing single-phase matrix converter is examined. First, system configuration and operation for both voltage sag and swell are described. Next, in order to suppress pulsations of the source voltage, a countermeasure using low pass filter and all pass filter is introduced. Then, compensating characteristics of the compensator are investigated for R-L load by simulation. Finally, the validity of the simulated results is confirmed by the experimental results.

• 대한전기학회논문지:전력기술부문A
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• 제49권10호
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• pp.509-515
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• 2000

This paper addresses a damping control strategy of Static Synchronous Series Compensator(SSSC) and analysis model for stability study. The effect of injected voltage source generated by SSSC is modelled as equivalent load. This model is thought to be reasonable for the stability study because the dynamics of SSSC is very fast compared with that of power system. Damping controller of SSSC is based on Transient Energy Function method. The proposed control strategy is insensitive to the operating conditions like power flow level because control law depends on the phase angles. The proposed analysis model and control strategy was confirmed by WSCC 9 bus system and two area system. Especially, the robustness of proposed control strategy is demonstrated with respect to multiple operating conditions in two area system.

• Journal of Power Electronics
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• 제14권4호
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• pp.742-753
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• 2014

In this paper, a new continuously and linearly controlled capacitive static VAR compensator is proposed for the automatic power factor correction of inductive single phase loads in 220V 50Hz power system networks. The compensator is constructed of a harmonic-suppressed TCR equipped with a new adaptive current controller. The harmonic-suppressed TCR is a new configuration that includes a thyristor controlled reactor (TCR) shunted by a passive third harmonic filter. In addition, the parallel configuration is connected to an AC source via a series first harmonic filter. The harmonic-suppressed TCR is designed so that negligible harmonic current components are injected into the AC source. The compensator is equipped with a new adaptive closed loop current controller, which responds linearly to reactive current demands. The no load operating losses of this compensator are negligible when compared to its capacitive reactive current rating. The proposed system is validated on PSpice which is very close in terms of performance to real hardware.

• 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.

• Journal of Power Electronics
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• 제3권3호
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• pp.185-196
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• 2003

In this paper, the single-phase static VAR compensator (SVC) is applied to regulate and stabilize the generated terminal voltage of the single-phase self-excited induction generator (single-phase SEIG) driven by a variable-speed prime mover (VSPM) under the conditions of the independent inductive load variations and the prime mover speed changes The conventional fixed gain PI controller-based feedback control scheme is employed to adjust the equivalent capacitance of the single-phase SVC composed of the fixed excitation capacitor FC in parallel with the thyristor switched capacitor TSC and the thyristor controlled reactor TCR The feedback closed-loop terminal voltage responses in the single-phase SEIG coupled by a VSPM with different inductive passive load disturbances using the single-phase SVC with the PI controller are considered and discussed herem. A VSPM coupled the single-phase SEIG prototype setup is established. Its experimental results are illustrated as compared with its simulation ones and give good agreements with the digital simulation results for the single-phase SEIG driven by a VSPM, which is based on the SVC voltage regulation feedback control scheme.

• 전력전자학회논문지
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• 제15권3호
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• pp.199-206
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• 2010

매트릭스 컨버터는 3상의 입력 전원이 전력용 반도체 스위치의 제어를 통해 3상의 부하에 직접 연결되는 에너지 변환 장치이다. 에너지 저장을 위한 직류단이 없어 매트릭스 컨버터의 입력 전류는 부하 전류와 스위치 상태에 직접 의존한다. 그러므로 불평형 또는 왜곡된 입력 전압은 원치 않은 출력 고조파 전류의 원인이 된다. 본 논문에서는 매트릭스 컨버터의 입력 전원 외란 상황에서 출력 전류를 개선하는 신경회로망 기반 전류 보상기를 제안한다. 제안된 기법 타당성과 유효성을 시뮬레이션과 실험을 통해 증명한다.