• Journal of Electrical Engineering and Technology
• /
• v.8 no.6
• /
• pp.1389-1399
• /
• 2013

A discrete controller is designed for low power dc-dc switched mode power supplies. The approach is based on time domain and the control loop continuously and concurrently tunes the compensator parameters to meet the converter specifications. A digital state feedback control combined with the load estimator provides a complete compensation, which further improves the dynamic performance of the closed loop system. Simulation of digitally controlled Buck converter is performed with MATLAB/Simulink. Experimental results are given to demonstrate the effectiveness of the controller using LabVIEW with a data acquisition card (model DAQ Pad - 6009).

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.4
• /
• pp.404-409
• /
• 2009

A DC power system has many loads with various functions. In particular, these sizable loads take the form of power electronic converters. When they are tightly regulated, the loads appear as constant power loads and result in negative incremental input impedance. Under certain conditions the effect of such loads on the power system is causes instability. In this paper, converter with a large storage capacitor and a lag compensator is proposed as a DC bus conditioner to mitigate the voltage transients on the bus. In addition, the proposed control approach has the advantage of performing both the functions of mitigating the voltage bus transients and maintaining the level of energy stored. Simulation and experimental results showed that the proposed control method was operated well in a small-scale DC power system that contained subsystems with constant power characteristics, such as DC/DC converters and electrical drives.

• Proceedings of the KIPE Conference
• /
• 2004.07b
• /
• pp.760-763
• /
• 2004

The recent growth in the use of impactive and nonlinear loads, electronic, and medical devices sensitive to power quality has caused many power quality problems and power supply-and-demand problem. Recently, in power system not only the reliability of the power supply but also the DVR(Dynamic Voltage Restorer), UPS, and APF are being studied more and more. Hence, in this paper, Voltage sag detection algorithm for voltage sag corrector is proposed. Also, simple circuit for the experimental voltage sag is Introduced.

• Proceedings of the KIPE Conference
• /
• 2004.07b
• /
• pp.566-569
• /
• 2004

The recent growth in the use of impactive and nonlinear loads, electronic devices sensitive to power quality has caused many power quality problems. Recently, in power system, not only the reliability of the power supply but also the DVR(Dynamic Voltage Restorer) are being studied more and more. The DVR is a series compensator which can instantaneously compensate a voltage variation in supply side, and is a more effective than a existing UPS(Uninterruptible Power Supply) which can be only used in limited range of loads such as single load. Hence, in this paper, a study of inverter side L-C filter output Voltage for DVR is discussed.

• Proceedings of the KIEE Conference
• /
• 1988.11a
• /
• pp.269-272
• /
• 1988

This paper introduces a method to reduce the reactive power required by electronic converters. The instantaeous reactive power is calculated and compensated by the current controlled PWH voltage source converter connected parallel between the power lines and the converter. A high performance current control technique which is based on the current deviation vector is used for the PWM converter as compensator of reactive power. Accurate compensation of the reactive power and t control system ensuring fast response to the sudden change of loaf are attained. The converter structure and control scheme are discussed. Simulation of the system is performed.

• Journal of information and communication convergence engineering
• /
• v.16 no.1
• /
• pp.1-5
• /
• 2018

In radio-over-fiber (RoF) systems, nonlinear compensation is very important to meet the error vector magnitude (EVM) requirement of the mobile network standards. In this study, a nonlinear compensation technique based on an artificial neural network (ANN) is proposed for RoF systems. This technique is based on a backpropagation neural network (BPNN) with one hidden layer and three neuron units in this study. The BPNN obtains the inverse response of the system to compensate for nonlinearities. The EVM of the signal is measured by changing the number of neurons and the hidden layers in a RoF system modeled by a measured data. Based on our simulation results, it is concluded that one hidden layer and three neuron units are adequate for the RoF system. Our results showed that the EVMs were improved from 4.027% to 2.605% by using the proposed ANN compensator.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.6
• /
• pp.692-698
• /
• 1999

This paper analyzes the effect of DGS(Dispersed Generation System) on the voltage regulation of the traditional distribution system of which the voltage is controlled by the bank LDC(Line Drop Compensator). Through the simulation results for 22.9kV class distribution system with DGSs, some general relationships among the operating power factor and introduction limit of DGS, and the sending-end reference voltage determined by internal setting coefficients of the LDC are derived. Those relationships are that the introduction limit of DGS increases as the power factor of DGS goes from lagging to leading and also as the allowance of the sending-end reference voltage increases. From the relationships, a operation method of the power distribution system integrated with DGSs is proposed from the view point of the operating power factor of DGS and new voltage regulation method.

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2006.08a
• /
• pp.106-106
• /
• 2006

• Journal of Power Electronics
• /
• v.9 no.2
• /
• pp.267-274
• /
• 2009

This paper deals with a voltage and frequency (VF) controller for an isolated power generation system based on an asynchronous generator (AG) driven by a pico hydro turbine. The proposed controller is a combination of a static compensator (STATCOM) and an electronic load controller (ELC) for decoupled control of the reactive and active powers of the AG system to control the voltage and frequency respectively. The proposed generating system along with its VF controller is modeled in MATLAB using SIMULINK and PSB (Power System Block Sets) toolboxes. The performance of the controller is verified for the proposed system and feeding various types of consumer load such as linear/non-linear, balanced/unbalanced and dynamic loads.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.15 no.2
• /
• pp.54-60
• /
• 2007

In this paper, we suggest the high efficient control method based on general PI control law for a variable speed refrigeration system. In the variable speed refrigeration system, the capacity and the superheat are mainly controlled by an inverter and an electronic expansion valve, respectively, for saving energy and improving coefficient of performance. Thus, we proposed a decoupling model to eliminate the interfering loop between the capacity and superheat at first. Next, we designed PI controller to control the capacity and superheat independently and simultaneously. Finally, the control performance was investigated through some experiments. The experimental results showed that the proposed PI controller based on the decoupling model can obtain good control performance under the various control references and thermal load.