• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.19-25
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• 2012

About supply and demand to see that you need to match, the limitations of wind power capacity is low demand and the commitment of the general generator will exist between the minimum generation. if the turbine's output can be controlled, The limitation of wind power capacity will be adopted based on instant power generation. Namely, The minimum limits of wind power generation based load operation by calculating the amount that is higher than if the output should be restricted to highest operation. in this paper, we committed to the demand for low enough that the combination of the general generator of wind power capacity to accommodate the operation of determining whether the limit is intended to. For this, power system analysis program PSS/E was used, Jeju system by implementing the model simulations were performed.

• Progress in Medical Physics
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• v.11 no.2
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• pp.141-146
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• 2000

Power spectrum analysis is a powerful noninvasive tool for quantifying autonomic nervous system activity. In this paper, We developed a measuring system for Autonomic Nervous Activity by using power spectrum analysis method to obtain the activities of autonomic nervous system. This system adopt a isolated power for patient's safety. In this system, Two output signal is obtained - R-R interval time variability and Respiration time variability. Time variability is use to find out some disease related to Autonomic Nervous System. Experimental tested range is 30 ～ 240 BPM for ECG and 15～80 BPM for Respiration.

• Journal of Power Electronics
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• v.13 no.2
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• pp.313-321
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• 2013

This paper describes the operation analysis results of a communication-based DC micro-grid using a hardware simulator developed in the lab. The developed hardware simulator is composed of distributed generation devices such as wind power, photovoltaic power and fuel cells, and energy storage devices such as super-capacitors and batteries. Whole system monitoring and control was implemented using a personal computer. The power management scheme was implemented in a main controller based on a TMS320F28335 chip. The main controller is connected with the local controller in each of the distributed generator and energy storage devices through the communication link based on a CAN or an IEC61850. The operation analysis results using the developed hardware simulator confirm the ability of the DC micro-grid to supply the electric power to end users.

• Journal of Power Electronics
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• v.12 no.1
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• pp.164-171
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• 2012

Variable step size maximum power point trackers (MPPTs) are widely used in photovoltaic (PV) systems to extract the peak array power which depends on solar irradiation and array temperature. One essential factor which judges system dynamics and steady state performances is the scaling factor (N), which is used to update the controlling equation in the tracking algorithm to determine a new duty cycle. This paper proposes a novel stability study of variable step size incremental resistance maximum power point tracking (INR MPPT). The main contribution of this analysis appears when developing the overall small signal model of the PV system. Therefore, by using linear control theory, the boundary value of the scaling factor can be determined. The theoretical analysis and the design principle of the proposed stability analysis have been validated using MATLAB simulations, and experimentally using a fixed point digital signal processor (TMS320F2808).

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.4
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• pp.711-716
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• 2011

This paper defines a generator reactive reserve considering power system network. Conventional generator reserve is calculated by the difference between the maximum reactive power output of generator and the current reactive power of generator. However, all generators could not affect on the whole power system. Thus, the effective generators should be selected by sensitivity analysis. The sensitivity depends on network configuration is the relation between generator reactive power outputs and reactive power loads. Using the sensitivity, the effective generator reactive reserve can be calculated.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2176_2177
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• 2009

This paper describe the power quality measuring result of the inter-connected residental PV system. The power quality measuring for inter-connected residental PV system are important to verify their performance and effect of power distribution system with inter-connected residental PV system. Also, these power quality measuring and analysis are essential to improve electrical safety. In order to evaluate influence of power distribution system with inter-connected residental PV system, we measure and analyze power quality index such as power, voltage, current, harmonic, THD, flicker index, power factor and frequency using DEWE5000.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.224-228
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• 2012

According to the results of Probabilistic Safety Assessment(PSA) for a Nuclear Power Plant(NPP), an Emergency Power Supply(EPS) system has been considered as one of the most important safety system. Especially, the interests in the reliability of the EPS system have been increased after the severe accidents of Fukushima Daiichi. Firstly, we performed the risk assessment and the importance analysis of the EPS system based on the PSA models of the reference plant, which is the Korean standard NPP type. Considering a portable Diesel Generator(DG) system as the reliability reinforcement of the EPS system, we modified the PSA models and performed the risk impact assessment and the importance analysis. Although the reliability of the potable DG could be about 20% of the reliability of the alternative AC DG, we identified that Core Damage Frequency(CDF) was decreased by at least 4.6%. In addition, the risk impacts due to the unavailability of the EPS system on CDF were decreased.

• Nuclear Engineering and Technology
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• v.41 no.1
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• pp.91-98
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• 2009

The "3+3 Process" for safety critical software for nuclear power plants' I&C (Instrumentation and Control system) has been developed in this work. The main idea of the "3+3 Process" is both to simplify the software development and safety analysis in three steps to fulfill the requirements of a software safety plan [1]. The "3-Step" software development process consists of formal modeling and simulation, automated code generation and coverage analysis between the model and the generated source codes. The "3-Step" safety analysis consists of HAZOP (hazard and operability analysis), FTA (fault tree analysis), and DV (design validation). Put together, these steps are called the "3+3 Process". This scheme of development and safety analysis minimizes the V&V work while increasing the safety and reliability of the software product. For assessment of this process, validation has been done through prototyping of the SDS (safety shut-down system) #1 for PHWR (Pressurized Heavy Water Reactor).

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.25-31
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• 2011

The purpose of power system maintenance is to prevent equipment failure. The maintenance strategy should be designed to balance costs and benefits because frequent maintenance increases cost while infrequent maintenance can also be costly due to electricity outages. This paper proposes maintenance modeling of a power distribution system using reliability centered maintenance (RCM). The proposed method includes comprehensive equipment modeling and impact analysis to evaluate the effect of equipment faults. The problem of finding the optimum maintenance strategy is formulated in terms of dynamic programming. The applied power system is based on the RBTS Bus 2 model, and the results demonstrate the potential for designing a maintenance strategy using the proposed model.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.108-117
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• 2010

The main contents of this paper are the PQM system construction case and distribution system harmonic voltage analysis. The PQM system has constructed by KEPCO in order to investigate power quality of distribution power system for new power quality standard of KEPCO. In result, we have confirmed that voltage harmonic measurement value of the high voltage contract customer 8 households is suitable the KEPCO harmonic standard tentative plan. And the voltage harmonic value of distribution line end side is not always more high than source side by harmonic current offset effect. In the future, acquired data by season, region, load from the PQMS will be used on the resonable harmonic standard enactment in KEPCO.