• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권8호
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• pp.3086-3101
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• 2021

To supply precise marketing and differentiated service for the electric power service department, it is very important to predict the customers with high sensitivity of electric power failure. To solve this problem, we propose a novel grouped 𝑙_1/2 sparsity constrained logistic regression method for sensitivity assessment of electric power failure. Different from the 𝑙₁ norm and k-support norm, the proposed grouped 𝑙_1/2 sparsity constrained logistic regression method simultaneously imposes the inter-class information and tighter approximation to the nonconvex 𝑙₀ sparsity to exploit multiple correlated attributions for prediction. Firstly, the attributes or factors for predicting the customer sensitivity of power failure are selected from customer sheets, such as customer information, electric consuming information, electrical bill, 95598 work sheet, power failure events, etc. Secondly, all these samples with attributes are clustered into several categories, and samples in the same category are assumed to be sharing similar properties. Then, 𝑙_1/2 norm constrained logistic regression model is built to predict the customer's sensitivity of power failure. Alternating direction of multipliers (ADMM) algorithm is finally employed to solve the problem by splitting it into several sub-problems effectively. Experimental results on power electrical dataset with about one million customer data from a province validate that the proposed method has a good prediction accuracy.

• 전력전자학회논문지
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• 제24권3호
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• pp.181-190
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• 2019

Active power decoupling circuits have emerged to eliminate the inherent second-order ripple power in a single-phase power conversion system. This study proposes a design method to determine the optimal capacitance for active power decoupling circuits to achieve high power density. Minimum capacitance is derived by analyzing ripple power in a passive power decoupling circuit, a buck-type circuit, and a capacitor-split-type circuit. Double-frequency ripple power decoupling capabilities are also analyzed in three decoupling circuits under a 3.3 kW load condition for a battery charger application. To verify the proposed design method, the performance of the three decoupling circuits with the derived minimum capacitance is compared and analyzed through the results of MATLAB -Simulink and hardware-in-the-loop simulations.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 추계학술대회
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• pp.291-292
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• 2011

This paper proposes an extraction method for reactor parameters in atmosphere plasma power supplies. This method is performed by detecting phase difference between inverter voltage and current, and extracting the reactance through reactive power. The validity of the proposed scheme is investigated through simulation results and experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.210-213
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• 2001

This paper presents a efficient algorithm for calculating power transfer capability in interconnected large power system. The approach is based on interior point method. The efficiency of this method is favorable for large systems. IEEE RTS-96 power system is utilized to evaluate the proposed method.

• 대한전기학회논문지:전력기술부문A
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• 제49권6호
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• pp.305-311
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• 2000

This paper presents a hybrid algorithm for solving optimal power flow(OPF) in order to enhance a systems capability to cope with outages, which is based on combined application of evolutionary computation and local search method. The efficient algorithm combining main advantages of two methods is as follows : Firstly, evolutionary computation is used to perform global exploitation among a population. This gives a good initial point of conventional method. Then, local methods are used to perform local exploitation. The hybrid approach often outperforms either method operating alone and reduces the total computation time. The objective function of the security constrained OPF is the minimization of generation fuel costs and real power losses. The resulting optimal operating point has to be feasible after outages such as any single line outage(respect of voltage magnitude, reactive power generation and power flow limits). In OPF considering security, the outages are selected by contingency ranking method(contingency screening model). The OPF considering security, the outages are selected by contingency ranking method(contingency screening model). The method proposed is applied to IEEE 30 buses system to show its effectiveness.

• 전력전자학회논문지
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• 제20권5호
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• pp.448-455
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• 2015

A model predictive control (MPC) method without individual PWM has been recently researched to simplify and improve the control flexibility of a multilevel inverter. However, the input power of each H-bridge cell and the switching frequency of switching devices are unbalanced because of the use of a restricted switching state in the MPC method. This paper proposes a control method for balancing the switching patterns and cell power supplied from each isolated dc source of a cascaded H-bridge inverter. The supplied dc power from isolated dc sources of each H-bridge cells is balanced with the proposed cell balancing method. In addition, the switching frequency of each switching device of the CHB inverter becomes equal. A simulation and experimental results are presented with nine-level and five-level three-phase CHB inverter to validate the proposed balancing method.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1798-1806
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• 2018

When a contingency occurs in a large transmission route in a power system, it can generate various instabilities that may lead to a power system blackout. In particular, transient instability in a power system needs to be immediately addressed, and preventive measures should be in place prior to fault occurrence. Measures to achieve transient stability include system reinforcement, power generation restriction, and generator tripping. Because the interpretation of transient stability is a time domain simulation, it is difficult to determine the efficacy of proposed countermeasures using only simple simulation results. Therefore, several methods to quantify transient stability have been introduced. Among them, the single machine equivalent (SIME) method based on the equal area criterion (EAC) can quantify the degree of instability by calculating the residual acceleration energy of a generator. However, method for generator tripping effect evaluation does not have been established. In this study, we propose a method to evaluate the effect of generator tripping on transient stability that is based on the SIME method. For this purpose, the measures that reflect generator tripping in the SIME calculation are reviewed. Simulation results obtained by applying the proposed method to the IEEE 39-bus system and KEPCO system are then presented.

• Journal of Power Electronics
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• 제15권1호
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• pp.54-64
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• 2015

This paper presents a current sensorless maximum power point tracking (MPPT) control method for dual-mode photovoltaic (PV) module-type interleaved flyback inverters (ILFIs). This system, called the MIC (Module Integrated Converter), has been recently studied in small PV power generation systems. Because the MIC is an inverter connected to one or two PV arrays, the power system is not affected by problems with other inverters. However, since the each PV array requires an inverter, there is a disadvantage that the initial installation cost is increased. To overcome this disadvantage, this paper uses a flyback inverter topology. A flyback inverter topology has an advantage in terms of cost because it uses fewer parts than the other transformer inverter topologies. The MPPT control method is essential in PV power generation systems. For the MPPT control method, expensive dc voltage and current sensors are used in the MIC system. In this paper, a MPPT control method without current sensor where the input current is calculated by a simple equation is proposed. This paper also deals with dual-mode control. Simulations and experiments are carried out to verify the performance and effectiveness of the proposed current sensorless MPPT control method on a 110 [W] prototype.

• 전기학회논문지
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• 제57권1호
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• pp.65-72
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• 2008

This paper describes the development of a novel islanding detection method, which uses the signal cross-corelation scheme between the injected reactive current and the power frequency deviation. The existing method, which injects the reactive current of 2.5-5% to the rated current and detects the frequency deviation directly, brings about lowing the power quality due to the harmonic pollution. The proposed method eliminates the weak point of the existing method, because it injects the reactive current less than 1% to the rated current. The operational feasibility was verified through computer simulations with PSCAD/EMTDC software, and experimental works with a 10kVA hardware prototype. The proposed method can detect the islanding status effectively without lowing the power quality of interconnected distributed generation system.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.133-140
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• 2002

This paper investigates the applicability of the modified Lanczos method using the power technique, which was developed in the field of quantum physics, to the eigenproblem in the field of engineering mechanics by introducing matrix-powered Lanczos recursion and numerically evaluating the suitable power value. The matrix-powered Lanczos method has better convergence and less operation count than the conventional Lanczos method. By analyzing four numerical examples, the effectiveness of the matrix-powered Lanczos method is verified and the appropriate matrix power is also recommended.