• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.1
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• pp.1-10
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• 2015

This paper proposes a control algorithm for permanent magnet synchronous generators with a back-to-back three-level neutral-point clamped voltage source converter in a medium-voltage off-shore wind power system under unbalanced grid conditions. Specifically, the proposed control algorithm compensates for unbalanced grid voltage at the PCC (Point of Common Coupling) in a collector bus of an off-shore wind power system. This control algorithm has been formulated based on symmetrical components in positive and negative synchronous rotating reference frames under generalized unbalanced operating conditions. Instantaneous active and reactive power is described in terms of symmetrical components of measured grid input voltages and currents. Negative sequential component of AC input current is injected into the PCC in the proposed control strategy. The amplitude of negative sequential component is calculated to minimize the negative sequential component of grid voltage under the limitation of current capability in a voltage source converter. The proposed control algorithm enables the provision of balanced voltage at the PCC resulting in the high quality generated power from off-shore wind power systems under unbalanced network conditions.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.61-69
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• 2012

Smart Grid is the next-generation intelligent power grid that maximizes energy efficiency with the convergence of IT technologies and the existing power grid. Smart Grid is created solution for standardization and interoperability. Smart Grid industry enables consumers to check power rates in real time for active power consumption. It also enables suppliers to measure their expected power generation load, which stabilizes the operation of the power system. Smart industy was ecolved actively cause Wireless communication is being considered for AMI system and wireless communication using ZigBee sensor has been applied in various industly. In this paper, we proposed efficient addressing scheme for improving the performance of the routing algorithm using ZigBee in Smart Grid environment. A distributed address allocation scheme used an existing algorithm has wasted address space. Therefore proposing x, y coordinate axes from divide address space of 16 bit to solve this problem. Each node was reduced not only bitwise but also multi hop using the coordinate axes while routing than Cskip algorithm. I compared the performance between the standard and the proposed mechanism through the numerical analysis. Simulation verify performance about decrease averaging multi hop count that compare proposing algorithm and another. The numerical analysis results show that proposed algorithm reduce multi hop than ZigBee distributed address assignment and another.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.20-30
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• 2013

An intelligent grid computing architecture is proposed and developed for transient stability constrained total transfer capability evaluation of future smart grid. In the proposed intelligent grid computing architecture, a model of generalized compute nodes with 'able person should do more work' feature is presented and implemented to make full use of each node. A timeout handling strategy called conditional resource preemption is designed to improve the whole system computing performance further. The architecture can intelligently and effectively integrate heterogeneous distributed computing resources around Intranet/Internet and implement the dynamic load balancing. Furthermore, the robustness of the architecture is analyzed and developed as well. The case studies have been carried out on the IEEE New England 39-bus system and a real-sized Chinese power system, and results demonstrate the practicability and effectiveness of the intelligent grid computing architecture.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.1
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• pp.49-60
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• 2015

Smart Grid devices are the major components of the Smart Grid. They collect and process a variety informations relating power services and support intelligent power services by exchanging informations with other SG devices or systems. However, If a SG device is attacked, the device can provide attack route to attacker and attacker can attack other SG devices or systems using the route. It may cause problem in power services. So, when cyber incident is happened, we need to acquire and examine digital evidence of SG device quickly to secure availability of SG. In this paper, we designed remote evidence acquisition system to acquire digital evidences from SG devices to response quickly to incidents of SG devices. To achieve this, we analyzed operating environment of SG devices and thought remote digital evidence acquisition system of SG devices will be more effective than remote digital evidence acquisition system targeted general IT devices. So, we introduce design method for SG devices remote evidence acquisition system considered operating environment of SG devices.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.1
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• pp.49-67
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• 2014

This paper proposes a real time pricing model for smart grid considering consumers' behavior, real time price elasticity, and exogenous price. Based on the proposed model, we found the weight of utility over cost is the most sensitive factor compared to other factors. Also, if the electricity price is set to be changed too sensitively to energy consumption, it is warned that real time pricing sometimes can cause increment of peak-time demand and volatility. Finally, real time pricing could be less efficient when the difference between the maximum and the minimum consumption level is small.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.1
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• pp.97-105
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• 2012

In order to avoid duplication in patents, papers and research subjects, many researchers have to review previous research work and patents with various methods. To reduce the our efforts in preview of research work, in this paper, we present scientometric analysis including Analysis of Index Level, International Cooperation Research Network, Analysis of Key Organizations and their Authors to help researchers to avoid duplication problems in field of smart grid.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.6
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• pp.111-125
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• 2010

There is a growing interest in "smart grid" technology, especially after the government recently announced "low-carbon green-growth industry" project. A smart grid uses "smart meters", which can be deployed in any power-consuming places like homes and factories. It has been shown that smart meters have several security weaknesses. There is, however, no protection profile available for smart meters, which means that safety with using them is not guaranteed at all. This paper analyzes vulnerabilities of smart meters and the relevant attack methods, thereby deriving the security functions and requirements for smart meters. Finally, we propose a protection profile based on Common Criterion v3.l for smart meters.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.335-336
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• 2014

This paper investigates the design of coupled inductor for minimum inductor current ripple in rapid traction battery charger systems. Based on the general circuit model of coupled inductor together with the operating principles of dc-dc converter, the relationship between the ripple size of inductor current and the coupling factor is derived under the different duty ratio. The optimal coupling factor which corresponds to a minimum inductor ripple current becomes -1, i.e. a complete inverse coupling without leakage inductance, as the steady-state duty ratio operating point approaches 0.5. In an opposite manner, the optimal coupling factor value of zero, i.e. zero mutual inductance, is required when the steady-state duty ratio operating point approaches either zero or one. Coupled inductors having optimal coupling factor can minimize the ripple current of inductor and battery current resulting in a reliable and efficient operation of battery chargers.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.1
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• pp.91-103
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• 2015

This paper investigates control algorithms for a doubly fed induction generator with a back-to-back three-level neutral-point clamped voltage source converter in a medium-voltage wind power system under unbalanced grid conditions. Negative sequence control algorithms to compensate for unbalanced conditions have been investigated with respect to four performance factors: fault ride-through capability, instantaneous active power pulsation, harmonic distortions, and torque pulsation. The control algorithm having zero amplitude of torque ripple indicates the most cost-effective performance in terms of torque pulsation. The least active power pulsation is produced by a control algorithm that nullifies the oscillating component of the instantaneous stator active and reactive power. A combination of these two control algorithms depending on operating requirements and depth of grid unbalance presents the most optimized performance factors under generalized unbalanced operating conditions, leading to a high-performance DFIG wind turbine system with unbalanced grid adaptive features.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.5
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• pp.1001-1011
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• 2014

Smart Grid Devices could have security vulnerabilities that have legacy communication networks because of the fact that Smart Grid employs bi-directional communications and adopted a variety of communication interface. Consequently, it is required to build concrete response processes and to minimize the damage of the cyber attacks including security evaluation and certification methods. DCU is designed to collect meter data from numerous smart meter and send to utility's server so DCU installed between smart meter and utility's server. For this reason, If DCU compromised by attacker then attacker could use DCU to launching point for and attack on other devices. However, DCU's security evaluation and certification techniques do not suffice to be deployed in smart grid infrastructure. This work development DCU protection profile based on CC, it is expected that provide some assistance to DCU manufacturer for development of DCU security target and to DCU operator for help safety management of DCU.