Junmin Cha

Nodal probabilistic congestion and reliability evaluations of a transmission system under the deregulated electricity market

This paper presents a method for evaluating nodal probabilistic congestion and reliability indices of transmission systems. Quantitative evaluation of transmission system reliability is very important because successful operation of an electric power system in the deregulated electricity market depends on transmission system reliability management. The key point is that the reliability level of the transmission system is equal to the reliability level difference between the composite power system (HLH) and the generation system (HLI). Risk indices of a composite power systems are larger than those of the generation system as the composite power systems include uncertainties and capacity limits of the transmission lines. The characteristics and effectiveness of this methodology are illustrated by the case study using a small test system.

A study on wind speed prediction using artificial neural network at Jeju Island in Korea

The importance of renewable energy sources has been growing at a high rate as a result of being environment friendly. In particular, wind power is one of the most successfully utilized of such sources to produce electrical energy. The available wind energy depends on the wind speed, which is a random variable. For the wind-farm operator, this poses difficulty in the system scheduling and energy dispatching, as the schedule of the wind-power availability is not known in advance. This paper proposes to use the two-layered artificial neural networks for predicting the actual wind speed from the previous values of the same variable.

Transmission System Expansion Planning Considering Outage Cost

This paper proposes a method for choosing the best composite power system expansion plan considering an annual outage cost assessment. The proposed method minimizes the investment budget (economics) for constructing new generating units and transmission lines as well as the annual outage cost subject to deterministic (demand constraint) and probabilistic reliability criterion (LOLER), while considering the uncertainties of system elements. It models the power system expansion problem as an integer programming one. The method solves for the optimal strategy using a probabilistic theory-based branch and bound method that utilizes a network flow approach and the maximum flow-minimum cut set theorem. The proposed method is applied to a 5-bus MRBTS, the test results demonstrate that the proposed method is suitable for solving the composite power system expansion planning problem subject to practical future uncertainties.

Web based online realtime information system for reliability of composite power system including wind turbine generators

This paper proposes a new methodology for evaluating the probabilistic reliability of a grid constrained composite power system including wind turbine generators(WTG). The proposed model can consider capacity limitations and transmission line forced outage rates. The importance of renewable energy sources has been growing at a high rate as a result of being environment friendly. In particular, wind energy is one of the most successfully utilized such source to produce electrical energy. The random nature of wind speed can be incorporated in the evaluation by representing the WTG by multi state models. Furthermore, web based online real-time reliability integrated information system (WORRIS) was developed with the proposed methodology in this paper. This paper describes architecture of the WORRIS Version 1.0 system developed preliminarily in this study. It is originally a reliability information system based one day go ahead system.

Flexible Maintenance Scheduling of Generation System by Multi-Probabilistic Reliability Criterion in Korea Power System

A new technique using a search method which is based on fuzzy multi-criteria function is proposed for GMS(generator maintenance scheduling) in order to consider multi-objective function. Not only minimization of probabilistic production cost but also maximization of system reliability level are considered for fuzzy multi-criteria function. To obtain an optimal solution for generator main- tenance scheduling under fuzzy environment, fuzzy multi-criteria relaxation method(fuzzy search method) is used. The practicality and effectiveness of the proposed approach are demonstrated by simulation studies for a real size power system model in Korea in 2010. by fuzzy search method has been developed. It is expected that more flexible solution can be obtained because fuzzy set theory that can reflect the subjective decision of deci- sion-maker has been used in this study(7)-(11). An alterna- tive method for flexible GMS using various kinds of objec- tive functions is proposed in this paper. The effectiveness of the proposed approach are demonstrated by simulation studies of a real size power system model.

Probabilistic Reliability Based Tie Line Capacity for Interconnecting Power Systems of South Korea, North Korea and Far East Russia

This paper illustrates to determinate how much is the reasonable capacity of tie lines in view point of probabilistic reliability in the North East Asia by using the tie line constrained equivalent assisting generator model (TEAG), which has been already developed by authors. A reliability evaluation program, it is named, NEAREL, based on the TEAG model was made. The reliability evaluation results for an interconnection scenario of the actual power systems of three countries in the North East Asia is introduced. The reasonable capacities of the tie line for three countries interconnection scenario for two target years, 2010 and 2020, are suggested from sensitivity analysis

Web based online real-time outage cost assessment information system of power system-II

This paper proposes a Web Based Online Real-time Outage Cost Assessment and Information System(WOROCAIS) for power system outage cost assessment. The proposed WOROCAIS is a kind of web based survey method for outage cost assessment. While conventional survey methods have done outage cost assessment based on survey paper lists collected by post mail or visiting customers, the proposed WOROCAIS is a web based online survey operation and assessment system. Therefore, it can curtail expenditure for survey and also is more convenient than conventional method. It will be set up for actual outage cost assessment system of KEPCO in South Korea in near future. The WOROCAIS will be applied in various research and actual planning and operation areas. First of all, the assessed results may be not only applied as one of objective function for generation system and grid expansion but also operational planning problems in power system.

Generators maintenance scheduling using combined fuzzy set theory and GA

The maintenance of generating units is implicitly related to power system reliability and has a tremendous bearing on the operation of the power system. A technique using a fuzzy search method which is based on fuzzy multi-criteria function has been proposed for GMS (generator maintenance scheduling) in order to consider multi-objective function. In this study, a new technique using combined fuzzy set theory and genetic algorithm (GA) is proposed for generator maintenance scheduling. The effectiveness of the proposed approach is demonstrated by the simulation results on a practical size test systems.

Fuzzy theory-based best generation mix considering renewable energy generators

This paper proposes a fuzzy linear programming (LP)-based solution approach for the long-term multi-stages best generation mix (BGM) problem considering wind turbine generators (WTG) and solar cell generators (SCG), and CO2 emissions constraints. The proposed method uses fuzzy set theory to consider the uncertain circumstances ambiguities associated with budgets and reliability criterion level. The proposed approach provides a more flexible solution compared to a crisp robust plan. The effectiveness of the proposed approach is demonstrated by applying it to solve the multi-years best generation mix problem on the Korean power system, which contains nuclear, coal, LNG, oil, pumped-storage hydro, and WTGs and SCGs.

A study on the fuzzy ELDC of composite power system based on probabilistic and fuzzy set theories

This paper illustrates a new fuzzy effective load model for probabilistic and fuzzy production cost simulation of the load point of the composite power system. A model for reliability evaluation of transmission system using fuzzy set theory is proposed for considering the flexibility or ambiguity of capacity limitation and over load of transmission lines which is subjective matter characteristics. The conventional probabilistic approach was also used to model the uncertainties related with the objective matters for forced outage rates of generators and transmission lines in the new model. The methodology is formulated in order to consider the flexibility or ambiguity of load forecasting as well as capacity limitation and over load of transmission lines. It is expected that the fuzzy CMELDC (composite power system effective load duration curve) proposed in this study will provide some solutions to many problems based on nodal and decentralized operation and control of an electric power systems under competition environment in future. The characteristics of this new model are illustrated by some case studies of very simple test system.