• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.111-114
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• 2000

Harmonics and fundamental reactive power of nonlinear loads in serious unbalanced power condition are compensated by current synchronous detection(CSD) theory which is also acceptable for single phase power system, but the CSD theory is not suitable any more in case of controlled independently harmonics and reactive component. Therefore a new algorithm the extended current synchronous detection (ECSD)theory for a three phase active power filter based on decomposition of fundamental reactive distorted components is proposed in this paper. The proposed ECSD theory is simulated and tested comparison with a few power theories under asymmtrical condition in power system.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.1-7
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• 2008

Superconducting Magnetic Energy Storage (SMES) can inject or absorb real and reactive power to or from a power system at a very fast rate on a repetitive basis. These characteristics make the application of SMES ideal for transmission grid control and stability enhancement. The purpose of this paper is to introduce the SMES model and scheme to control the active and reactive power through the power electronic device. Furthermore, an optimal priority scheme is proposed for the combination of active and reactive power control to be able to stabilize power transient swings.

• Journal of Electrical Engineering and Technology
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• v.3 no.3
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• pp.373-378
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• 2008

In this paper, an Active Power Filter (APF) is implemented using a dSPACE DS1104 processor to compensate harmonics and reactive power produced by nonlinear load. The reference source current is computed based on the measurement of harmonics in the supply voltage and load current. A hysteresis based current controller has been implemented in a DSP processor for injecting the compensating current into the power system, so that APF allows suppression of the harmonics and reactive power component of load current, resulting in a supply current that is purely sinusoidal. Simulation and experimental results of the proposed APF to meet the IEEE-519 standards are presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.3
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• pp.96-101
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• 2015

Induction machine requires a rotating magnetic field for energy conversion. The current to generate a rotating magnetic field is the magnetization current. This magnetization current corresponds to the reactive power. Reactive power is higher than active power at start-up of induction motor. As the rotation speed is increased, their magnitudes are reversed each other. The active power is higher than the reactive power at near the synchronous speed. This paper is dealing with the analysis result for the changes of the magnetizing current and reactive power when the induction machine is operating as a motor or generator near synchronous speed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.22-27
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• 2012

Correct and fast detection of a micro-grid (MG) islanding is essential to the MG since operation, control and protection of the MG depend on an operating mode i.e., an interconnected mode or an islanding mode. When islanding occurs, the frequency of the point of common coupling (PCC) is not the nominal frequency during the transient state owing to the frequency rise or drop of generators in the MG. Thus, the active and reactive power calculated by the frequency domain based method such as Fourier Transform might contain some errors. This paper proposes an islanding detection algorithm for the MG based on the instantaneous active and reactive powers delivered to the dedicated line in the time domain. During the islanding mode, the instantaneous active and reactive powers delivered to the dedicated line are constants, which depend on the voltage of the PCC and the impedance of the dedicated line. In this paper, the instantaneous active and reactive powers are calculated in the time domain and used to detect islanding. The performance of the proposed algorithm is verified under various scenarios including islanding conditions, fault conditions and load variation using the PSCAD/EMTDC simulator. The results indicate that the algorithm successfully detects islanding for the MG.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.6
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• pp.1138-1145
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• 2009

This paper presents an active and reactive power compensator for the wind power system with squirrel-cage induction generator. The output power of a wind power system changes irregularly according to the variation of wind speed. The developed system is able to continuously compensate the active and reactive power. The 3-phase inverter operates for the compensation of reactive power, while the DC/DC converter with super-capacitors operates for the compensation of active power. The operational feasibility of the proposed model was verified by simulations with PSCAD/EMTDC and the feasibility of hardware implementation was confirmed by experimental works with a scaled hardware model. The proposed compensator can be expected that developed system may be used to compensated the abrupt power variation due to sudden change of wind speed or sudden power-drop by tower effect. It can be also applied for the distributed generation and the Micro-Grid.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.5
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• pp.221-229
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• 2003

This paper suggests a control algorithm of 3-phase 3-wire series active power filter. This suggested algorithm can compensate source harmonics and reactive power in 3-phase 3-wire power distribution systems. These harmonics are generated by nonlinear loads such as diode rectifiers and thyristor converters. This control algorithm extracts a compensation voltage reference from performance function without phase transformation. Therefore, this control algorithm is simpler than any other conventional control algorithms. 3-phase 3-wire series active power filters which have a harmonic voltage source and a harmonic current source are manufactured and experiments are carried out to verify the effectiveness of suggested control algorithm.

• Journal of Power Electronics
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• v.9 no.5
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• pp.691-699
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• 2009

This paper presents the analysis of series active power filter for reactive power compensation, load balancing, harmonic elimination, and neutral current eradication in three-phase four-wire power systems. Generally, the three-phase four-wire system is widely employed in distributing electric energy to several office building and manufacturing plants. In such systems, the third harmonic and its 3rd harmonics are termed as triple and zero sequence components that do not cancel each other in the system neutral. Consequently, the triple harmonics add together creating a primary source of excessive neutral current. Regarding this concern, this paper presents a new control algorithm for a series hybrid active system, whereas the control approach it adopts directly influence its compensation characteristics. Hence, the advantage of this control algorithm is the direct extraction of compensation voltage reference without phase transformations and multiplying harmonic current value by gain and the required rating of the series active filter is much smaller than that of a conventional shunt active power filter. In order to show the effectiveness of the proposed control algorithm, experiments have been carried out.

• Journal of Wind Energy
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• v.9 no.4
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• pp.47-56
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• 2018

This paper introduces an active power dependent standard characteristic curve, Q(P) to compensate for voltage variations due to the output of distributed generation. This paper presents an efficient control method of grid-connected inverters by comparing and analyzing voltage variation magnitude and line loss according to the compensation method. Voltage variations are caused not only by active power, but also by the change of reactive power flowing in the line. In particular, the system is in a relatively remote place in a coastal area compared with existing power plants, so it is relatively weak and may not be suitable for voltage control. So, since it is very important to keep the voltage below the normal voltage limit within the specified inverter capacity and to minimize line loss due to the reactive power. we describe the active power dependent standard characteristic curve, Q(P) method and verify the magnitude of voltage variation by simulation. Finally, the characteristics of each control method and line loss are compared and analyzed.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.66-68
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• 2004

The current source HVDC using thyristor valves requires the reactive power compensator, the increasement of short circuit ratio(SCR) by AC source, and the harmonic filter in power transmission. The voltage source HVDC that controls active power and reactive power independently can minimize the requirements and also can be used as a reactive power source without additional reactive power compensators. In this paper, the solution of supplying active power using direct current transmission and compensating additional reactive power at the heavy load zone in metropolitan area is proposed and verified by simulations.