• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.1
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• pp.18-24
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• 2005

Various problems such as the increase of the power loss and the voltage instability may often occur in the case of low load power factor. The demand of reactive power increases continuously with the growth of active power and the restructuring of electric power companies makes the comprehensive management of reactive power a troublesome problem, so that the systematic control of load power factor is required. In this paper, the load power factor sensitivity of the generation cost is derived and it is used for determining the locations of reactive power compensation devices effectively and for enhancing the load power factor appropriately. In addition, the voltage variation penalty cost is introduced and the integrated costs including the voltage variation penalty cost are used for determining the value of the load power factor from the point of view of the economic investment and voltage regulation. It is shown through the application to a large-scale power system that the load power factor can be enhanced effectively and appropriately using the load power factor sensitivity and integrated costs.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.813-817
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• 1998

This paper proposes a new control strategy of bidirectional uninterruptible power supply(UPS) with the performance of active power filter which compensate the harmonics and reactive power. To improve the transient response for the effective compensation in active power filter mode. It is considered that a simple and precise calculation method of the compensation reference current for the harmonics and reactive power compensation. So a novel closed-loop control strategy is used to calculate the reference current. The system model and control algorithm are described and the system performance is verified by the simulation and experimental results.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.770-772
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• 1993

This paper is a study of a reactive-power compensator. It make using Power-MOSFET that be little quantity driving-power, easy to control, and be passible to highspeed wich be capable to achieve a reactive power compensator, to get rid of harmonics. On account of having no particular control circuit, composing not need to energy storage element and feedback control compered the previous power transformer in the system organization. It efficiqntly ueed to be in power factor compensation variable load.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1174-1176
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• 2000

This paper presents a new control strategy of the active power filter to compensate the fundamental and high order reactive power. Using the proposed control strategy, the calculation of active and reactive power of the load is not required. So the system configurations and the controller can be constructed very simply. To decrease the load of active power filter, the LC passive filter bank can be used without any additional strategy. In this paper, the algorithm of the proposed new control strategy is discussed and the experimental results are shown.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.254-262
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• 2008

This paper presents an active use of doubly-fed induction-generator(DFIG)-based variable-speed wind-turbine for voltage control in power system operation. For reasonable simulation studies, a detail dynamic model of a DFIG-based wind-turbine grid-connected system is presented. For the research objective, an innovative reactive power control scheme is proposed that manipulates dynamically the reactive power from the voltage source converter(VSC) with taking into account its operating state and limits.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.4
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• pp.566-574
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• 2013

In this paper, direct power control system for three-phase PFC AC/DC converter without the source voltage sensors is proposed. The sinusoidal input current and unity effective power factor are realised based on the estimated flux in the observer. Both active and reactive power calculated using estimated flux. The estimation of flux is performed based on the reduced-order virtual flux observer using the actual currents and the command control voltage. Moreover, source voltage sensors are replaced by a estimated flux. DC output voltage has been compensated by DC output ripple voltage estimation algorithm. The active and reactive powers estimation are performed based on the estimated flux and Phase angle. The proposed algorithm is verified through simulation and experiment.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1363-1371
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• 2017

In this paper, an improved Direct Power Control (DPC) algorithm is presented for grid connected three phase PWM rectifiers. The new DPC approach is based on two main tasks. First the optimization of the look-up table, which is well-known in conventional DPC, is outlined for selecting the optimum converter output voltage vectors. Secondly a very simple and effective method is used to directly calculate their duty cycles from the power errors. Therefore, the measured active and reactive powers are made to track their references using hysteresis controllers. Then two vectors are selected and applied during one control cycle to minimize both the active and reactive power ripples. The main advantages of this method are that there is no need of linear current controllers, coordinates transformations or modulators. In addition, the control strategy is able to operate at constant switching frequencies to ease the design of the power converter and the AC harmonic filter. The control exhibits a good steady state performance and improves the dynamic response without any overshoot in the line current. Theoretical principles of the proposed method are discussed. Both simulation and experimental results are presented to verify the performance and effectiveness of this control scheme.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.9
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• pp.100-107
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• 2013

Since the West Sea experiences a big difference in tides, the output power of the small marine hydroelectric power plant varies with the tide. When an induction generator is used here for small hydroelectric power, the reactive power capacitor should be installed at the generator main bus to compensate for the changes in power. As such, the sizing method for the power compensation of the induction generator is reviewed and an optimal method for compensation is suggested. The self-excitation minimum capacitor capacity method, which prevents high voltages, and the power factor automatic control method, which retains a power factor of greater than 90% are reviewed. The compensation effect of reactive power is confirmed through a case study.

• Journal of Power Electronics
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• v.14 no.2
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• pp.369-382
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• 2014

A growing dynamic electrical demand has created an increasing interest in utilizing nonconventional energy sources like Photovoltaic (PV), wind power, etc. In this context, this paper focuses on the design and development of a composite power controller (CPC) in the decoupled double synchronous reference frame (DDSRF) combining the advantages of direct power control (DPC) and voltage oriented control (VOC) for a PV sourced grid connected inverter. In addition, a controller with the inherent active filter configuration is tested with nonlinear and unbalanced loads at the point of common coupling in both grid connected and autonomous modes of operation. Furthermore, the loss and reactive power compensation due to a non-fundamental component is also incorporated in the design, and the developed DDSRF model subsequently allows independent active and reactive power control. The proposed developed model of the controller is also implemented using MATLAB-Simulink-ISE and a Xilinx system generator which evaluate both the simulated and experimental setups. The simulation and experimental results confirm the validity of the developed model. Further, simulation results for the DPC are also presented and compared with the proposed CPC to further bring out the salient features of the proposed work.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.6
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• pp.330-335
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• 1999

This paper proposed the p-q-r coordinate system where the instantaneous active power p, and the two instantaneous reactive powers qq, qr were defined. The three power components are linearly independent, so the compensation for the two instantaneous reactive powers leads to control the two components of the current space vector. With the theory, the neutral current of a three-phase four-wire system can be eliminated by only compensating the instantaneous reactive power using no energy storge element.