• 제어로봇시스템학회논문지
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• 제6권3호
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• pp.235-240
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• 2000

In this paper a digital-control algorithm of a power system suing a high-speed PWM for a MRI system is proposed. The MRI system requires an elaborate ladder-shaped current source. And the load of current source is the inductance with resistance. For the inductive load a voltage output of the power system has hi호 frequency components. Therefore this system requires high-speed PWM above 80KHz, A high speed PWM control algorithm which satisfies those conditions is designed. Finally the performance of proposed control algorithm is shown by simulation.

• 전기학회논문지
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• 제64권1호
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• pp.16-22
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• 2015

As the development of Battery Energy Storage System(BESS) and the increasing of intermittent energy sources like wind power and photovoltaic, the application of BESS in load frequency control is considered as an effective method. To evaluate the effectiveness of BESS application in frequency control, we defined a governor free model of BESS to conduct dynamic simulation. Using the BESS dynamic model, we implemented the power system dynamic model including steam, gas and hydro turbine generators. In this paper we study the control performance of BESS in primary frequency control. The effect of BESS speed regulation rate and response time on governor free operation is investigated. In addition, we compared BESS from steam turbine generator in view point of frequency regulation.

• 수산해양기술연구
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• 제26권3호
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• pp.275-281
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• 1990

This study suggests a new type shaft generator driven by hydraulic power suitable for small size vessels. Since the shaft generator system is very easy to be affected by disturbances such as speed variation of the main engine and the load variation of the generator, a robust servo control must be performed to obtain stable electric power with constant frequency. So, in this study the robust servo control method is adopted to the controller design. Dynamic characteristics on the frequency variations of the electric power output according to the disturbances are investigated by computer simulations. From the considerations of the computer simulation results, it is ascertained that the shaft generator system proposed in this study had good control performances.

• 전자공학회논문지SC
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• 제38권1호
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• pp.53-60
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• 2001

전력전자의 많은 응용분야에서 고주파 공진형 인버터가 이용되며, 이들 공진형 인버터의 출력 전력을 제어하기 위하여는 PAM(Pulse Amplitude Modulation), PFM(Pulse Frequency Modulation) 혹은 PWM(Pulse Width Modulation) 기법들이 이용된다. 그리고 이들 공진형 인버터는 변화하는 부하 상태에서도 신뢰성 있게 동작하기 위하여 출력추파수를 제어하여야 한다. 본 논문에서는 공진형 인버터의 PWM 제어의 일환으로써 새로운 스위칭 방법을 제안하였다. 제안한 방법에 의하면, 변화하는 공진 주파수하에서도 최적의 공진 주파수와 출력 기본파 역률 1을 달성할 수 있다. 제안한 PWM 스위칭 방법의 상세한 알고리즘 및 출력특성을 기술하였다. 그리고 실험 결과를 통하여 제안한 방법의 타당성을 확인하였다.

• Wind and Structures
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• 제36권4호
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• pp.221-236
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• 2023

The lateral component of turbulence and the vortices shed in the wake of a structure result in introducing dynamic wind load in the acrosswind direction and the resulting level of motion is typically larger than the corresponding alongwind motion for a dynamically sensitive structure. The underlying source mechanisms of the acrosswind load may be classified into motion-induced, buffeting, and Strouhal components. This study proposes a frequency domain framework to decompose the overall load into these components based on output-only measurements from wind tunnel experiments or full-scale measurements. First, the total acrosswind load is identified based on measured acceleration response by solving the inverse problem using the Kalman filter technique. The decomposition of the combined load is then performed by modeling each load component in terms of a Bayesian filtering scheme. More specifically, the decomposition and the estimation of the model parameters are accomplished using the unscented Kalman filter in the frequency domain. An aeroelastic wind tunnel experiment involving a tall circular cylinder was carried out for the validation of the proposed framework. The contribution of each load component to the acrosswind response is assessed by re-analyzing the system with the decomposed components. Through comparison of the measured and the re-analyzed response, it is demonstrated that the proposed framework effectively decomposes the total acrosswind load into components and sheds light on the overall underlying mechanism of the acrosswind load and attendant structural response. The delineation of these load components and their subsequent modeling and control may become increasingly important as tall slender buildings of the prismatic cross-section that are highly sensitive to the acrosswind load effects are increasingly being built in major metropolises.

• 대한전기학회논문지
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• 제33권2호
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• pp.76-82
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• 1984

This paper presents the design and the optimal control method of current-fed half-brige switching regulator. To achieve fast response load current variation is fed to control input, and simple optimal control model has been derived with provision of current control loop in the control circuit. Test results show that the control system model is correct and 5ms response time has been obtained at 25 KHz switching frequency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.362-366
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• 1987

The amount of inflowing Air into the boiler has controlled by manipulating the opening of valve, damper and vane, as fan operated by induction motor operats at constant speed, but these control methods are not efficient. Thus VVVf(Variable Voltage Variable Frequency) control of fan has selected to improve efficiency and to acquire power savings. Control system of Air Flow is affected by nonlinearity caused by load variation, vane opening, etc. The analysis of control parameter causing nonlinearity is needed to acquire optimal control and excellent transient response. This paper provides modeling of boiler with various load conditions and vane opening, and analysis of this system.

• Journal of Power Electronics
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• 제13권1호
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• pp.161-169
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• 2013

This paper proposes a novel control strategy for a unified power quality conditioner (UPQC) including a series and a shunt active power filter (APF) to compensate the harmonics in both the distorted supply voltage and the nonlinear load current. In the series APF control scheme, a proportional-integral (PI) controller and a resonant controller tuned at six multiples of the fundamental frequency of the network ($6{\omega}_s$) are performed to compensate the harmonics in the distorted source. Meanwhile, a PI controller and three resonant controllers tuned at $6n{\omega}_s$(n=1, 2, 3) are designed in the shunt APF control scheme to mitigate the harmonic currents produced by nonlinear loads. The performance of the proposed UPQC is significantly improved when compared to that of the conventional control strategy thanks to the effective design of the resonant controllers. The feasibility of the proposed UPQC control scheme is validated through simulation and experimental results.

• 대한전기학회논문지
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• 제45권4호
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• pp.474-483
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• 1996

In this paper, as a part of the method improving stability, the load-flow calculation in D.C. power system and the models for stability analysis are studied with A.C-D.C. interconnected power systems transmission performed. Moreover, the theory is established in relation to each control method of D.C. power systems. Then the stability of A.C-D.C.interconnected power systems is compared and considered by the way of dividing the operating control method of the rectifier inverter converter into ACR-AVR, APR-A.gamma.R, A.alpha.R-ACR. The dynamics characteristic of terminal voltage, frequency, active-reactive power and rotor angle of the generator with disturbances and load fluctuations is considered. In addition, the characteristic of direct voltage, direct current, power and control systems. From this the comparative analysis of the direct current control method, the possibility of the stability analysis of A.C.-D.C. interconnected power system is considered. (author). refs., figs., tabs.

• 전력전자학회논문지
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• 제27권1호
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• pp.18-25
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• 2022

The cold staring issue of permanent magnet synchronous motors (PMSM) is a chronic problem in the field of PMSM sensorless drives. A traditional starting method, called the I-F method, is widely adopted because of its simple structure. However, when using this method, the pre-defined magnitude and frequency of the starting current should be changed according to the condition of the load and machine inertia. In this paper, a smart and simple algorithm for the cold starting of PMSM is proposed. In the proposed method, an integrated control angle from the estimated electrical rotor speed is used for vector control such as the indirect vector control of the induction machine. Thus, very stable cold starting is performed regardless of the machine load condition or inertia changing.