• 한국전자파학회논문지
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• 제12권6호
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• pp.994-1001
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• 2001

본 논문에서는 이동 통신 시스템에서의 PIC기법으로 간섭을 제거하여 개선된 SIR을 기반으로 하는 전력 제어 방식을 제안한다. 일반적으로 전력 제어는 SIR을 기반으로 하는 방식이 사용되고 있다. 그러나 이 방식은 시스템의 안정성을 떨어뜨리는 Positive Feedback 현상을 발생시킨다. 따라서 제안된 전력 제어 기법은 SIR의 변수인 간섭신호를 감소시켜 개선된 SIR을 기반으로 하는 전력제어를 수행하여 시스템의 안정화를 도모하였다. 또한 이동국에서 기존의 Up-Down전력 명령대신 Up-Maintain-Down기법을 이용하여 성능을 향상시켰다. 새로운 전력 제어 기법인 개선된 SIR방식과 기존의 방식을 모의 실험을 통하여 비교, 제안된 시스템의 성능 개선을 확인했다.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1357-1368
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• 2017

The lack of controllability over the wind causes fluctuations in the output power of the wind generators (WGs) located at the wind farms. Distribution Static Compensator (DSTATCOM) equipped with Battery Energy Storage System (BESS) can significantly smooth these fluctuations by injecting or absorbing appropriate amount of active power, thus, controlling the power flow of WGs. But because of the component aging and thermal drift, its harmonic filter parameters vary, resulting in performance degradation. In this paper, Quantitative Feedback Theory (QFT) is used as a robust control scheme in order to deactivate the effects of filter parameters variations on the wind power generation power smoothing performance. The proposed robust control strategy of the DSTATCOM is successfully applied to a microgrid, including WGs. The simulation results obviously show that the proposed control technique can effectively smooth the fluctuations in the wind turbines' (WT) output power caused by wind speed variations; taking into account the filter parameters variations (structural parameter uncertainties).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.669-671
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• 2004

This paper presents a MIMO nonlinear controller for the power system consisting of a turbine and a synchronous generator connected to an infinite bus. The controller proposed is based on feedback input-output linearization; its main goal is to regulate the terminal voltage and frequency, and is to improve the transient stability under large disturbances and unexpected faults. It is guaranteed that the voltage converges to its reference value exponentially, and that the frequency and the mechanical/electrical power are bounded. The design procedure is tested on a single machine infinite bus power system through simulations, and is seen to be effective.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.348-350
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• 1996

A new reset winding clamped forward converter with transformer voltage feedback technique for power factor correction with a single-switch/single-stage is proposed. The proposed converter gives the good power factor correction, low current harmonic distortions, and tight output voltage regulation. The prototype shows the IEC555-2 requirements are met satisfactorily with nearly unity power factor.

• 한국초전도ㆍ저온공학회논문지
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• 제15권1호
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• pp.19-24
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• 2013

In this paper, the Superconductor flywheel energy storage system (SFESS) was used for the load frequency control (LFC) of an interconnected 2 area power system. The robust SFESS controller using quantitative feedback theory (QFT) was designed to improve control performance in spite of parameter uncertainty and unexpected disturbances. An overlapping decomposition method was applied to simplify SFESS controller design for the interconnected 2 area power system. The model for simulation of the interconnected 2 area power system included the reheat steam turbine, governor, boiler dynamics and nonlinearity such as governor deadband and generation rate constraint (GRC). To verify robust performance of proposed SFESS controller, dynamic simulation was performed under various disturbances and parameters variation of power system. The results showed that the proposed SFESS controller was more robust than the conventional method.

• Journal of electromagnetic engineering and science
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• 제2권2호
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• pp.93-99
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• 2002

The Cartesian loop chip which is one of key devices in narrow-band Walky-Talky transmitter using RZ-SSB modulation method was designed and implemented with 0.35 Um CMOS technology. The reduced size and low cost of transmitter were available by the use of direct-conversion and Cartesian loop chip, which improved the power efficiency and linearity of transmitting path. In addition, low power operation was possible through CMOS technology. The performance test results of transmitter showed -23 dBc improvement of IMD level and -30 dEc below suppression of SSB characteristic in the operation of Cartesian loop chip (closed-loop). At that time, the transmitting power was about 37 dBm (5 W). The main parameters to improve the transmitting characteristic and to compensate the distortion in feed back loop such as DC-offset, loop gain and phase value are interfaced with notebook PC to be controlled with S/W.

• 대한전기학회논문지:전력기술부문A
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• 제50권4호
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• pp.197-207
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• 2001

In this paper, design problem of QFT-PSS using Genetic Algorithm(GA) is investigated for power systems with parameter variation and disturbance uncertainties. A robust controller for uncertain power systems can be designed automatically such that the cost of feedback is minimized and all robust stability and performance specifications are satisfied. It is shown that the proposed design method not only automates loop shaping but also improves design quality and improves the quality with a reduced order controller. The robustness of the proposed controller has been investigated on a single machine infinite bus model. The results are shown that the proposed QFT-PSS using GA is more robust tan conventional PSS.

• 전기학회논문지
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• 제65권8호
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• pp.1400-1406
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• 2016

This paper presents a new adaptive converter control approach for electric motor systems whose voltage source is excited from photovoltaic (PV) power generators. First, an electric model is represented with dynamic states and output velocity of such DC motor systems. We propose a hybrid converter control law in which a state feedback control is applied as an auxiliary control framework. Moreover, control parameter estimation is derived to realize adaptive converter systems for effective control performance against stochastic PV power excitation in practice. We carry out stability analysis for such converter system by using a well-known eigenvalue theory. Lastly, numerical simulation is conducted to test reliability of the proposed converter control approach and prove its superiority in the control point of view.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 추계학술대회 논문집
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• pp.115-118
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• 2001

This paper presents a new sensorless control scheme using simple duty signal feedback technique in DC-DC converters. The proposed sensorless control scheme (DFC) has the characteristics that they show the same as operation performance of current mode control by using duty feedback technique without current sensor as well as present better dynamic response performance than conventional sensorless current mode control (SCM) in case that input source is perturbed by step change or DC input source includes the . harmonics. Also, the proposed control scheme has good noise immunity and simple control circuits since they have one feedback loop, and can be applied to all DC-DC converters. The concept and control principles of the proposed control scheme are explained in detail and the validity of the proposed control scheme is verified through several interesting simulated results.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권6호
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• pp.754-759
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• 2016

A transformer feedback low-noise amplifier (LNA) is implemented in a standard $0.18{\mu}m$ CMOS process, which exploits drain-to-gate transformer feedback technique for wideband input matching and operates across entire 3~5 GHz ultra-wideband (UWB). The proposed LNA achieves power gain above 9.5 dB, input return loss less than 15.0 dB, and noise figure below 4.8 dB, while consuming 8.1 mW from a 1.8-V supply. To the authors' knowledge, drain-to-gate transformer feedback for wideband input matching cascode LNA is the first adopted technique for UWB application.