• Journal of Power Electronics
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• v.17 no.3
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• pp.798-810
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• 2017

This paper presents a combined system of a small-capacity inverter and multigroup delta-connected thyristor switched capacitors (TSCs). The system is referred to as a hybrid static compensator (HSC) and has the functions of dynamic reactive power compensation and harmonic suppression. In the proposed topology, the load reactive power is mainly compensated by the TSCs. Meanwhile the inverter is meant to cooperate with TSCs to achieve continuous reactive power compensation, and to filter the harmonics generated by nonlinear loads and the TSCs. First, the structure and mathematical model of the HSC are discussed Then the control method of the HSC is presented. An improved reduced order generalized integrator (ROGI)-based selective current control method is adopted in the inverter to achieve high-performance reactive and harmonic current compensation. Meanwhile, a switch control strategy is proposed to implement precise and fast switching of the TSCs and to avoid changing the time delay needed by the conventional switch strategy. Experiments are implemented on a 20 KVA HSC prototype and the obtained results verify the validity of the proposed HSC system.

• Korean Journal of Forensic Psychology
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• v.13 no.2
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• pp.99-119
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• 2022

Research on sex offense has shown that sex offenders are very heterogeneous. Sex offenders are heterogeneous in their probability of risk of recidivism. Some sex offenders are known to be much higher in their tendencies to reactivate than others. The study examined the predictive and explanatory power of static and dynamic risk factors in STATIC-99 and HAGSOR-Dynamic which have been used in Korean correctional facilities since 2014. STATIC-99 and HAGSOR-Dynamic showed moderate predictive accuracy for all crimes(AUC = .737, AUC = .597, respectively, ps < .001). However, when examining sex crime alone, only STATIC-99 predicted recidivism significantly(AUC = .743, p < .001). The incremental predictive power of HAGSOR-Dynamic was confirmed; the explanatory power of Model 2 comprising both static and dynamic risk factors were significant beyond Model 1 comprising only static factors(∆χ²= 12.721, p < .001), but this tendency was only applied to the model of all crimes. These findings were discussed with implications of practicing the sex offender assessment and treatment.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.89-92
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• 1996

This paper describes a detailed simulation model of the static condenser (STATCON) to analyze the dynamic interaction with the ac transmission line. The static condenser was represented by a 12-pulse voltage-source inverter sharing an energy storage dc capacitor. The voltage-source inverter consists of two 6-pulse bridges modeled with ideal gate-turn-off switches. The control system for the static condenser was designed through a mathematical model deduced from the equivalent circuit. Simulation results show that the conceived model is very effective to analyze the dynamic interaction between the static condenser and the ac transmission system.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.280-284
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• 1997

In this paper theoretical foundation of distribution STATCON, the operating characteristics of D-STATCON, the overview of control technologies for power factor correction of D-STATCON, and the PWM current control of D-STATCON and simulated results are given to shows the practical feasibility of a Flexible AC Transmission System and Distribution Static Condenser.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.468-469
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• 2010

DSTATCOM(Distribution STATic COMpensator) is one of the custom power devices, and protects a distribution line from unbalanced and harmonic current caused by non-linear and unbalanced loads. Conventional researches use a LPF(Low Pass Filter) to eliminate ripple component at the calculation of compensation current. This paper proposes a calculation of compensation current using phase shift that can be a counterproposal of conventional methods using LPF.

• Progress in Superconductivity
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• v.10 no.1
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• pp.55-59
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• 2008

A Superconductor Flywheel Energy Storage System(SFES) mainly consists of a pair of non-contacting High Temperature Superconductor(HTS) bearings that provide very low frictional losses, a composite flywheel with high energy storage density. The HTS bearings, which offer dynamic stability without active control, are the key technology that distinguishes the SFES from other flywheel energy storage devices, and great effort is being put into developing this technology. The Superconductor Journal Bearing(SJB) mainly consists of HTS bulks and a stator, which holds the HTS bulks and also acts as a cold head. Static properties of HTS bearings provide data to solve problems which may occur easily in a running system. Since stiffness to counter vibration is the main parameter in designing an HTS bearing system, we investigate SJB magnetic force through static properties between the Permanent Magnet(PM) and HTS. We measure stiffness in static condition and the results are used to determine the optimal number of HTS bulks for a 100kWh SFES.

• KIEE International Transactions on Power Engineering
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• v.3A no.3
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• pp.161-167
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• 2003

This paper presents a study performed to investigate the steady-state operational strategies of UPFCs in the Jeollanam-Do system in Korea. The objective of the study was to determine the UPFC operating points under normal and contingency conditions. The study consists of developing load flow models to simulate different load levels with and without UPFCs in the system, assessing the effectiveness of UPFCs by contingency analysis, and introducing optimal corrective actions for removing voltage problems caused by contingencies. The paper describes analytical tools, models and approach. It also includes analysis and discussion of the study results. The paper contributes to the area of transmission operational studies with FACTS applications.

• Journal of Power Electronics
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• v.14 no.4
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• pp.742-753
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• 2014

In this paper, a new continuously and linearly controlled capacitive static VAR compensator is proposed for the automatic power factor correction of inductive single phase loads in 220V 50Hz power system networks. The compensator is constructed of a harmonic-suppressed TCR equipped with a new adaptive current controller. The harmonic-suppressed TCR is a new configuration that includes a thyristor controlled reactor (TCR) shunted by a passive third harmonic filter. In addition, the parallel configuration is connected to an AC source via a series first harmonic filter. The harmonic-suppressed TCR is designed so that negligible harmonic current components are injected into the AC source. The compensator is equipped with a new adaptive closed loop current controller, which responds linearly to reactive current demands. The no load operating losses of this compensator are negligible when compared to its capacitive reactive current rating. The proposed system is validated on PSpice which is very close in terms of performance to real hardware.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.10
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• pp.58-67
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• 2006

In this paper, real-time reactive power/power factor compensating equipment is suggested for improving power quality at electrical railway's substation in marshalling yard and designing optimal capacity of compensating equipment for actual apply at current marshalling yard. For this purpose, several kind of real-time reactive power/power factor compensating equipments are introduced and SVG(Static Var Generator) as optimal compensating equipment that is suitable for load characteristics of substation in marshalling yard is suggested. This paper shows proper simulations by suggested equipment using PSIM software and describe basic compensating principle and simulation results. Optimal capacity design for applying current marshalling yard is based on real measured power quality data. Power quality improvement that is performed by SVG as real-time reactive power/power factor compensating equipment is estimated at electrical railway's substation in marshalling yard. As reference, real-time reactive power/power factor compensating equipment is composed by voltage source inverter and DC capacitors.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1206-1208
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• 2000

The Static var compensators(SVC) are intensively studied to realize high performance power equipment for electric power systems. Rapid and continuous reactive compensation by the SVC contributes to voltage stabilization, power oscillation damping, overvoltage suppression, minimization of transmission losses and so on. In this paper, instantaneous power vector theory which can expresses the instantaneous apparent power vector is proposed to control reactive power. The validity of the proposed method is confirmed by simulation studies.