Geun-Pyo Park

A Reliability-Centered Approach to an Optimal Maintenance Strategy in Transmission Systems Using a Genetic Algorithm

Electric power transmission utilities try to maximize profit by reducing electricity supply costs and operation costs while maintaining their reliability. Developing maintenance strategies is one of the effective ways to achieve these profitable goals. The reliability-centered maintenance approach is a key method in providing optimal maintenance strategies. It considers the tradeoffs between the upfront maintenance costs and the potential costs of reliability losses. Since a transmission system is a group of different kinds of equipment and the reliability of the electric facilities varies with time, an equipment state model using a modified semi-Markov chain is proposed. In addition, a genetic algorithm is used to find the optimal maintenance strategies from a large class of possible maintenance scenarios. These optimal maintenance strategies have been tested on an IEEE 9-bus system and an IEEE 118-bus system; the results show that the proposed method minimizes the total expected costs.

Northeast Asia Interconnection-based integration of DG, DR, HVDC, and nuclear load-following under Smart Grid in the South Korean power system

This paper, based on the Northeast Asia (NEA) power system interconnection, presents an integration of renewable generation (RG), demand response (DR) or distributed generation (DG), high-voltage direct-current (HVDC), and nuclear power plant load-following operation under Smart Grid (SM) in the South Korean power system. The reliable power system depends on considering the reliability that affect after the system is connected or disconnected. The land-to-land power system interconnection in NEA countries will use as the back to back (BTB) technique for power transmission lines; whereas the point-to-point (PTP) will be used for over-sea interconnection, such as a Jeju Island and South Korea-Japan submarine transmission. In this paper, we will suggest how to design and analyze the operation mechanism/algorithm of the reliability side for the NEA, and an integration of RG, DR, HVDC, and nuclear power plant load-following operation under SM in the South Korean power system. Also, we present an inter-area power flow map for a power flow analysis for NEA countries to relieve the possible future power imbalances within the metropolitan areas or the southeastern area of Korea.

Generalized Reliability Centered Maintenance Modeling Through Modified Semi-Markov Chain in Power System

The purpose of power system maintenance is to prevent equipment failure. The maintenance strategy should be designed to balance costs and benefits because frequent maintenance increases cost while infrequent maintenance can also be costly due to electricity outages. This paper proposes maintenance modeling of a power distribution system using reliability centered maintenance (RCM). The proposed method includes comprehensive equipment modeling and impact analysis to evaluate the effect of equipment faults. The problem of finding the optimum maintenance strategy is formulated in terms of dynamic programming. The applied power system is based on the RBTS Bus 2 model, and the results demonstrate the potential for designing a maintenance strategy using the proposed model.

Modified dynamic programming based unit commitment technique

This paper represents a modified dynamic programming solution to the unit commitment (UC) problem. The UC is a complex decision-making process because of multiple constraints which may not be violated while finding the optimal or suboptimal commitment schedule. There are many methods to solve the UC problem gradually. So, before we present our method, we will show the drawbacks of the standard dynamic programming methods which use general purpose optimization techniques to the UC problem. The priority list method, the lagrange relaxation and the mixed integer linear programming (MILP) are possible to apply to a real power system for performing the unit commitment. However, by using these methods, we could not get an optimal solution but only a suboptimal silution. Therefore we propose to get an optimal solution by using dynamic programming. Performing dynamic programming takes a lot of simulation time, so it is not optimal to use in a real power system for performing the unit commitment. Therefore, we need a modified dynamic programming method to satisfy both the simulated and the real power system to get the optimal solution. For those not familiar with UC problem, we introduce the constraints, production cost and start-up cost. The goal of the objective function is in cost minimization, so we use the economic dispatch using the lambda iteration method when we calculate the production costs. Finally, we compare the UC solution by using both methods.

Optimal maintenance strategies for transmission systems using the Genetic Algorithm

Electric power transmission utilities not only decrease their operation costs, but also take opportunities to maximize their profit. While they should operate to meet customer needs for reliability which is one of major concerns of power delivery. Therefore they need to make the maintenance strategies considering the tradeoff between cost and reliability. In this paper, Genetic Algorithm (GA) is used to find optimal maintenance strategies for transmission systems. To consider aged and much different equipment, the equipment state model through modified semi-Markov chain is proposed. Also, the effects of equipment failure on the system are presented in terms of a cost using the DC-Optimal Power Flow (OPF). The results on the IEEE 9-bus system show the optimal maintenance strategy which minimizes operation costs.

Web-based power flow simulator for independent power distribution systems

In this paper, we develop a Web-based distributed power flow simulator (WDPFS) for a power distribution system undergoing conversion to a strategic business unit (SBU) operation for the division of the power distribution business sectors in South Korea. In the SBU, the distributed power flow algorithm should be changed as the system is divided so that each sector then needs its own operational system. These functions can be obtained by the Web-based power distribution power flow algorithm for the SUB of distributed power distribution system with distributed generations and can be easily exchanged by the boundary layer values among distributed power distribution systems. Also, the proposed distributed distribution power flow algorithm only solves active power, reactive, voltage, and angle using boundary conditions for contrary part systems. In this paper, we propose a Web-based distributed power flow simulator for a power distribution system undergoing SBUs after the division into power distribution business sectors.

Northeast Asia interconnection and virtual power system simulator design

In this paper, a virtual power system simulator (VPSS) using a virtual power plant (VPP) concept is introduced. VPSS efficiently emulates power system operations and electricity transactions in order to protect the access to future electricity markets utilizing the power system interconnections in Northeast Asia (NEA). This paper introduces methods on how to structure and operate the operative mechanism and the simulator design for these proposed inter-regional interconnections in the NEA. The inter-regional power system interconnection structure is expressed by using an interregional scenario performed by the Integrated Inter-Regional Transmission Organization (IIRTO). In these NEA countries, electric power bidding scenarios and price signal scenarios are options that are able to be defined by one VPSS based on the IIRTO parameters.

Economic evaluation for generation investment in South Korea electricity market

The electricity power industry has transformed from an integrated structure to a competitive market. Generally, investing generators in the electric power industry requires huge funds and takes long periods of construction in the need to continuously provide stable electricity power. Before the reform of the power industry took place in South Korea, the government had planed the electric power investment to keep the balance of supply and demand in the long run, and the Korea Electric Power Corporation (KEPCO), which is an integrated structure of the electric power industry in South Korea used to invest electric power equipments. However, after the deregulation, a new concept of expansion plan has been introduced to the electric power industry. The main change from the previous plan is that generation companies have an opportunity to plan their own investment in electricity power equipments with less constraints. In this paper, we represent the method that evaluates the economic efficiency between the investment in electric power generators in an existing monopoly formation and the investment made after reform. And we apply the methods to the electricity market in South Korea. The research contribution of this paper is in the methodological use of economic evaluation generation investment.

REX10 interconnection and environmental greenhouse gas reduction in south korea

In this paper, we introduce REX-10 (Regional Energy Reactor, 10MWth) system development and power system interconnection in the utilization sides of renewable energy resources for the purpose of reduction of environmental greenhouse gas emissions. The REX-10 consists of nuclear reactor power generation units with thorium fuel. We describe the assumed strategy for power interconnection between the island areas and a KEPCO (Korea Electric Power Corporation) power system. The electric power capacity for the regional power generation per unit has less than 10 MW of power output. The newly designed REX-10 has been developed to be placed in an island ares to maintain system safety, island, etc. Also, REX-10 units for distributed generations (DGs) are connected to the backbone transmission line of a KEPCO 154kV power system in South Korea. Additionally, this study on DGs using REX-10 is necessary and important with respect to the environmental energy policy for greenhouse gas reductions in Korea. Thus, we expect reduced carbon dioxide emissions of 6.448 million tons as compared with what coal-fired power plants would emit if they were to generate the same amount of electricity.

Application of particle swarm optimization for an optimal maintenance strategy in transmission systems

This paper presents the application of particle swarm optimization (PSO) technique to find the optimal maintenance strategy of transmission equipment with minimum total expected cost of generation cost, maintenance cost, repair cost and outage cost. Three types of transmission equipment, the overhead line, the underground cable and the insulator are considered. To consider aging, the equipment state model through modified Markov chain is proposed. Simulation is performed on IEEE 9-bus systems. The results obtained are quite encouraging and will be useful in maintenance scheduling.