• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.168-173
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• 2011

Recently, from a saving energy and environmental lighting sources point of view, using LED lighting have been increased rapidly. The colors of light was applied to the control of dimmers that is composed of red, green, blue, and white(RGBW) to improve the quality of visual environment. Moreover this study has been processed to develop adjustable dynamic LED lighting system on SPD and definitize the various spectral power distribution and color temperature of light through the control of the four dimmers. It is possible to combine up to $432^4$ kinds of light. Measurement of illuminance of range on working surface was as 7~l,831 lux. Application of visual environment for occupants can be expected according to control of lighting performance.

• Journal of Power Electronics
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• 제16권1호
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• pp.351-361
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• 2016

Power quality is a critical issue in distribution systems, where a dynamic voltage restorer (DVR) is commonly used to mitigate the voltage disturbances for loads. This paper deals with a nonlinear control for the three-phase four-wire (3P-4W) DVR under a grid voltage unbalance and nonlinear loads in the distribution system, where a novel control scheme based on the feedback linearization technique is proposed. Through feedback linearization, a nonlinear model of a DVR with a PWM voltage-source inverter (VSI) and LC filters is linearized. Then, the controller design of the linearized model is performed by applying the linear control theory, where the load voltages are kept constant by controlling the d-q-0 axis components of the DVR output voltages. To keep the load voltage unchanged, an in-phase compensation strategy is employed, where the load voltages are recovered to be the same as the previous voltage without a change in the magnitude. With this strategy, the performance of the DVR becomes faster and more stable even under unbalanced source voltages and nonlinear loads. The validity of the proposed control strategy has been verified by simulation and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.447-454
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• 1998

This paper describes a modeling and current control techniques of Distribution static condenser (D-STATCON) for power factor compensation. The current control is based on the predictive and the space vector PWM scheme. The predictive current controlled PWM D-STATCON can maintain its performance with power factor compensation and fixed switching frequency. By using the space vector control low ripple and offset in the current and the voltage as well as fast dynamic responses are achieved with a small DC link capacitance employed.

• Journal of Power Electronics
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• 제9권2호
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• pp.146-155
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• 2009

The static frequency converter (SFC) systems are used as a method of driving large synchronous machines in many power and industrial plants. In this paper, new control algorithms of SFC systems for starting gas turbo sets are proposed for a four quadrant operation: start-up at standstill; an acceleration up to the speed of the rated voltage; field weakening to reach the rated speed; synchronization to the main alternating current (AC) source; and dynamic braking to stop safely within the rating of the synchronous machine. Experimental results show that the proposed algorithms are proper and effective.

• 전기학회논문지
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• 제56권2호
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• pp.317-324
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• 2007

Most conventional hybrid systems using renewable energy sources have been applied for stand-alone operation, but Utility-interface may be an useful and viable option for hybrid systems. Grid-connected operation may have benefits such as reduced losses in power system distribution, utility support in demand side management, and peak load shaving. This paper addresses power control and dynamic performance of a grid-connected PV/wind/BESS hybrid system. At all times the PV way and the wind turbine are individually controlled to generate the maximum energy from given weather conditions. The battery energy storage system (BESS) charges or discharges the battery depending on energy gap between grid invertger generation and production from the PV and wind system. The BESS should be also controlled without too frequently repeated shifts in operation mode, charging or discharging. The grid inverter regulates the generated power injection into the grid. Different control schemes of the grid inverter are presented for different operation modes, which include normal operation, power dispatching, and power smoothing. Simulation results demonstrate that the effectiveness of the proposed power control schemes for the grid-interactive hybrid system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.251-255
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• 2003

This paper proposes a novel UPQC(unified power quality conditioner) based on H-bridge modules, isolated through single-phase multi-winding transformers. The dynamic performance of proposed system was analyzed by simulation with EMTDC/PSCAD, assuming that the UPQC is connected with the 22.9kV distribution line. The proposed system can be directly connected to the transmission line without series injection transformers. It has flexibility in expanding the operation voltage by increasing the number of H-bridge modules and can compensate reactive power, harmonics, voltage sag and swell, voltage unbalance. The control strategy for the proposing UPQC was derived using the instantaneous power method. The proposing UPQC has the ultimate capability of improving power quality at the point of installation on power distribution systems and can be utilized for the future distribution system.

• 전력전자학회논문지
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• 제27권3호
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• pp.192-199
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• 2022

In DC distribution systems, a TAB converter employing multiple transformers is one of the most widely used topologies due to its high power density, modularizability, and cost-effectiveness. However, the conventional control technique for a grid-connected mode in the TAB converter cannot maintain its reliability for an islanding mode under a blackout situation. In this paper, the islanding mode control technique is proposed to solve this issue. To verify the relative stability and dynamic characteristics of the control technique, small-signal models of both the grid connected and the islanding mode are derived. Based on the small-signal models, PI controllers are designed to provide suitable power control. The proposed control technique, the accuracy of small-signal models, and the performance of the controllers are verified by simulations and experiments with a 1-kW prototype TAB converter.

• Steel and Composite Structures
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• 제45권5호
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• pp.697-713
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• 2022

In the context of the finite elements method, the dynamic behavior of porous functionally graded double wishbone vehicle suspension structural system incorporating joints flexibility constraints under road bump excitation is studied and analyzed. The functionally graded material properties distribution through the thickness direction is simulated by the power law including the porosity effect. To explore the porosity effects, both classical and adopted porosity models are considered based on even porosity distribution pattern. The dynamic equations of motion are derived based on the Hamiltonian principle. Closed forms of the inertia and material stiffness components are derived. Based on the plane frame isoparametric Timoshenko beam element, the dynamic finite elements equations are developed incorporating joint flexibilities constraints. The Newmark's implicit direct integration methodology is utilized to obtain the transient vibration time response under road bump excitation. The presented procedure is validated by comparing the computational model results with the available numerical solutions and an excellent agreement is observed. Obtained results show that the decrease of porosity percentage and material graduation tends to decrease the deflection as well as the resulting stresses of the control arms thus improving the dynamic performance and increasing the service lifetime of the control arms.

• International Journal of Automotive Technology
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• 제8권6호
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• pp.791-798
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• 2007

The hydraulic hybrid vehicle(HHV) is an application of hydrostatic transmission technology to improve vehicle fuel economy and emissions. A relatively lower energy density of hydraulic accumulator and complicated coordinating operations between two power sources require a special energy management strategy to maximize the fuel saving potential. This paper presents a new type of configuration for parallel HHV to minimize the disadvantages of the hydraulic accumulator, as well as a methodology for developing an energy management strategy tailored specially for PHHV. Based on an analysis of the optimal energy distribution between two power sources over a representative urban driving cycle with a Dynamic Programming(DP) algorithm, a fuzzy-based optimal torque management strategy is designed and developed to control the torque distribution. Simulation results demonstrates that the optimal torque management strategy maximizes the advantages of this hybrid type of configuration, and the high power density characteristics of hydraulic technology effectively improve the robustness of the energy management strategy and fuel economy of the PHHV.

• Journal of Electrical Engineering and Technology
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• 제6권6호
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• pp.769-775
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• 2011

Custom power devices such as dynamic voltage restorer (DVR) and DSTATCOM are used to improve the power quality in distribution systems. These devices require real power to compensate the deep voltage sag during sufficient time. An interline DVR (IDVR) consists of several DVRs in different feeders. In this paper, a neural network is proposed to control the IDVR performance to achieve optimal mitigation of voltage sags, swell, and unbalance, as well as improvement of dynamic performance. Three multilayer perceptron neural networks are used to identify and regulate the dynamics of the voltage on sensitive load. A backpropagation algorithm trains this type of network. The proposed controller provides optimal mitigation of voltage dynamic. Simulation is carried out by MATLAB/Simulink, demonstrating that the proposed controller has fast response with lower total harmonic distortion.