• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.182-186
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• 1997

This paper presents a mathematical approach to implementing distributed optimal power flow (OPF), wherein a regional decomposition technique is adopted to parallelize the OPF. Three mathematical decomposition coordination methods are introduced firs to implement the proposed distributed scheme: the Auxiliary Problem Principle (APP), the Predictor-Corrector Proximal Multiplier Method (PCPM), and the Alternating Direction Method (ADM). Then two alternative schemes for modeling distributed OPF are introduced; the Dummy Generator-Dummy Generator (DGDG) scheme and Dummy Generator-Dummy Load (DGDL) scheme. We present the mathematical analyses of the proposed approach, and demonstrate the approach on several test, systems, including IEEE Reliability Test Systems and parts of the ERCOT (Electric Reliability Council of Texas) system.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.80-89
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• 2014

A stochastic optimal power flow (S-OPF) model considering uncertainties of load and wind power is developed based on chance constrained programming (CCP). The difficulties in solving the model are the nonlinearity and probabilistic constraints. In this paper, a limit relaxation approach and an iterative learning control (ILC) method are implemented to solve the S-OPF model indirectly. The limit relaxation approach narrows the solution space by introducing regulatory factors, according to the relationship between the constraint equations and the optimization variables. The regulatory factors are designed by ILC method to ensure the optimality of final solution under a predefined confidence level. The optimization algorithm for S-OPF is completed based on the combination of limit relaxation and ILC and tested on the IEEE 14-bus system.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.239-242
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• 2001

This paper presents a windows program package for solving security constrained OPF in interconnected power systems, which is based on the combined application of evolutionary programming(EP) and sequential quadratic programming(SQP). The objective functions are the minimization of generation fuel costs and system power losses. The control variables are the active power of the generating units, the voltage magnitude of the generator, transformer tap settings and SVC setting. The state variables are the bus voltage magnitude, the reactive power of the generating unit, line flows and the tie line flow. In OPF considering security, the outages are selected by contingency ranking method. 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). The OPF package proposed is applied to 10 machines 39 buses model system.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1000-1002
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• 1998

We present an approach to parallelizing optimal power flow (OPF) that is suitable for distributed implementation and is applicable to very large interconnected power systems. The objective of this paper is to find a set of control parameters with which the Auxiliary Problem Principle (Algorithm - APP) can be best implemented in solving optimal power flow (OPF) Problems. We employed several IEEE Reliability Test Systems to demonstrate the alternative parameter sets.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.12
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• pp.597-602
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• 2005

The introduction of competition in electricity market emphasizes the importance of sufficient transmission capacities to guarantee various electricity transactions. Therefore, when dispatch scheduling, transmission security constraints should be considered for the economic and stable electric power system operation. In this paper, we propose an optimal dispatch scheduling algorithm incorporating transmission security constraints. For solving these constraints, the dispatch scheduling problem is decomposed into a master problem to calculate a general optimal power flow (OPF) without transmission security constraints and several subproblems to inspect the feasibility of OPF solution under various transmission line contingencies. If a dispatch schedule given by the master problem violates transmission security constraints, then an additional constraint is imposed to the master problem. Through these iteration processes between the master problem and subproblems, an optimal dispatch schedule reflecting the post-contingency rescheduling is derived. Moreover, since interruptible loads can positively participate as generators in the competitive electricity market, we consider these interruptible loads active control variables. Numerical example demonstrates efficiency of the proposed algorithm.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.3
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• pp.133-138
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• 2006

This paper presents an Optimal Power Flow (OPF) algorithm using Interior Point Method (IPM) to swiftly and precisely perform the five minute dispatch. This newly suggested methodology is based on Affine Scaling Interior Point Method which is favorable for large-scale problems involving many constraints. It is also eligible for OPF problems in order to improve the calculation speed and the preciseness of its resultant solutions. Big-M Method is also used to improve the solution stability. Finally, this paper provides relevant case studies to confirm the efficiency of the proposed methodology.

• Journal of Electrical Engineering and Technology
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• v.11 no.4
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• pp.791-800
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• 2016

Optimal Power Flow (OPF) is an important operational and planning problem in minimizing the chosen objective functions of the power systems. The recent developments in power electronics have enabled introduction of dc links in the AC power systems with a view of making the operation more flexible, secure and economical. This paper formulates a new OPF to embrace dc link equations and presents a heuristic optimization technique, inspired by the behavior of fireflies, for solving the problem. The solution process involves AC/DC power flow and uses a self adaptive technique so as to avoid landing at the suboptimal solutions. It presents simulation results of IEEE test systems with a view of demonstrating its effectiveness.

• Journal of Oral Medicine and Pain
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• v.30 no.1
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• pp.79-85
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• 2005

This study was designed to confirm the association between the pain of Tension-Type Headache(TTH) patients and their Oral Parafunction(OPF). Patients with TTH(n=58) visited the Department of Oral Medicine, Kyung Hee University Dental Hospital during two months were recruited to this study. 20 patients with OPF(bruxism, clenching, bruxism & clenching) are the experimental group and 38 patients without OPF are the control group. Both groups were asked to answer the questionnaire based on the diagnostic criteria of TTH(IHS). Then it was analyzed statistically. This study was designed to confirm the association between the pain of Tension-Type Headache(TTH) patients and their Oral Parafunction(OPF). Patients with TTH(n=58) visited the Department of Oral Medicine, Kyung Hee University Dental Hospital during two months were recruited to this study. 20 patients with OPF(bruxism, clenching, bruxism & clenching) are the experimental group and 38 patients without OPF are the control group. Both groups were asked to answer the questionnaire based on the diagnostic criteria of TTH(IHS). Then it was analyzed statistically. 1. There was no difference in sex(p=0.91) and age(p=0.73) between two groups. 2. In the experimental group, dull pain was presented more frequently than in the control group. But, there was no difference between two groups(p=0.69). 3. In the experimental group, severe pain was presented more frequently than in the control group. But, there was no difference between two groups(p=0.40). 4. In the experimental group, pain shown bilaterally was presented more frequently than in the control group. But, there was no difference between two groups(p=0.52). 5. In the experimental group, pain was more increased by physical activities than in the control group. But, there was no difference between both groups(p=0.74). The pain of TTH patients with OPF was presented to be non-dull pain frequently and more bilaterally and severely, also increased more by physical activities than the pain of TTH patients without OPF. But, there was no significant difference between two groups. Therefore, it is considered that the pain of TTH is not influenced by OPF.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.347-349
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• 2000

Under an open transmission access, the generation dispatch is determined by the bidding process of market participants. Congestion occurs when the dispatch would result in the violation of operational constraints. Congestion problem is formulated and solved by OPF(optimal power flow) calculation. The objective functions in OPF are given as quadratic cost functions or piecewise linear functions of bidding functions. In this study, the optimization technique of generation dispatch is presented for the combination of two types of quadratic and linear cost functions.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.195-197
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• 2006

This paper presents new power development planning method. This method uses modified-OPF (Optimal Power Flow) includes attribution constrains. After solved the OPF, shadow prices of constraints are used making the weighting factors. These factors are used ordering new generators.