Seungpil Moon

Transmission system reliability evaluation of KEPCO system in face of deregulation

The reliability evaluation of a transmission system is being realized to play an important role in the electric power systems under the situation of deregulation, because the electricity transmission system will be planned, operated and maintained by an independent transmission administrator in the new electric industry structure. The new concept of the CMELDC (CoMposite power system Effective Load Duration Curves) has been developed to evaluate the nodal reliabilities, to simulate the nodal probabilistic production cost and to assess outage cost on the composite power systems by the authors in recently. Reliability of the transmission system can be also evaluated with the CMELDC. The methodology of reliability evaluation of the transmission system is based on the concept that the reliability level of a transmission system is equal to the difference in the reliability levels of the composite power systems(HLII) and generation system(HLI). In this study, the transmission system reliability of the KEPCO(Korea Electric Power Corporation) system was evaluated under a deregulated electricity market.

Generator maintenance scheduling considering air pollution based on the fuzzy theory

A new technique using a search method which is based on fuzzy multicriteria function is proposed for generator maintenance scheduling, considering the air pollution. Not only minimization of probabilistic production cost and maximization of system reliability level but also air pollution are considered for fuzzy multicriteria function. To obtain an optimal solution for generator maintenance scheduling under fuzzy environment, fuzzy multicriteria 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.

Development of the ELDC and reliability evaluation of composite power system using Monte Carlo method

This paper presents a method for constructing composite power system effective load duration curves (CMELDC) at load points by a Monte Carte method. The concept of effective load duration curves (ELDC) in power system planning is useful and important in both HLI and HLII. CMELDC can be obtained from convolution integral processing of the probability function of unsupplied power and the load duration curve at each load point. This concept is an analogy to the ELDC in HLI. The reliability indices (LOLP, EDNS) for a composite power system are evaluated using CMELDC. Differences in reliability levels between HLI and HLII come from considering with the uncertainty associated with the outages of the transmission system. It is expected that the CMELDC can be applied usefully to areas such as reliability evaluation, probabilistic production cost simulation and analytical outage cost assessment, etc. in HLII. DC load flow and Monte Carlo methods are used in this study. The characteristics and effectiveness of the methodology are illustrated by a case study of the IEEE RTS.

Development of an analytical method for outage cost assessment in a composite power system

This study proposes a new analytical method for assessing the outage cost of a composite generation and transmission system. Outages of the generation system and the transmission system were included in this study. First, the composite power system effective load duration curve ELDC (CMELDC) at HLII was developed from reliability evaluation of the composite power system in order to assess the outage cost at HLII. Secondly, mathematical expressions for the marginal outage cost function at each load point are formulated using relations between GNP (or GDP) and the electrical energy demand. Finally, the outage cost is calculated by combining the proposed CMELDC with the marginal outage cost function at each load point. The effectiveness of the proposed approach is demonstrated by the IEEE-RTS.

Transmission system expansion planning of KEPCO system (Youngnam area) using fuzzy set theory

This study proposes a new method for transmission system expansion planning using fuzzy integer programming. It presents stepwise cost characteristics analysis which is a practical condition of actual systems. A branch and bound method which includes the network flow method and the maximum flow-minimum cut set theorem has been used in order to carry out the stepwise cost characteristics analysis. Uncertainties of the permission of the construction cost and nonstrict reserve rate and load forecasting of expansion planning can be included for long-term transmission expansion planning and is also processed using fuzzy set theory in this study. A reasonable solution can be obtained using a fuzzy branch and bound method which includes the network flow method and maximum flow-minimum cut set theorem. Case studies on the Youngnam area of KEPCO (Korea Electric Power Corporation) system show that the algorithm proposed is efficiently applicable to the horizontal expansion planning of transmission systems in future.

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.