Yong Tae Yoon

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.

Analysis of energy savings using smart metering system and IHD (in-home display)

Many electric power suppliers are suffering from huge losses due to higher cost related to generation of resources, especially fossil fuel. Many ideas have been proposed to renovate the price distortion in the electricity market. Among these ideas, smart metering system has been considered as an effective method for improving the pattern in power consumption of energy consumers thus reducing the financial burden of electricity companies. In this paper, we reviewed smart metering system of other countries and explained our development of smart metering system specialized for Korean residential environments. With this developed system, we have conducted a pilot demonstration for 2 months in the winter season Dec. 2008 to Feb. 2009. 77 various sized households in two different cities volunteered to participate in this demonstration. During this demonstration, our study focused on verifying the effectiveness of IHD (In-Home Display) which is an essential component of Korean smart metering system. The result of this demonstration is also included in this paper.

Option Valuation Applied to Implementing Demand Response via Critical Peak Pricing

The purpose of this paper is to examine the economic and technical perspectives of critical peak pricing plan as an active demand response(DR) program. To implement a good DR program, there are three perspectives to be considered: regulatory, economic, and technical perspectives. This paper will assume that the regulatory perspective of DR is determined as critical peak pricing(CPP) plan and examine the other two. The economic perspective of CPP plan is the incentive of the plan conductor, or the profit of an energy service provider(ESP). The technical perspective is a method to maximize the incentive of CPP plan, or an ESPs profit. An ESP should decide when to call critical peaks within certain constraints to maximize her profit. This is done by predicting the market prices and following a similar method as evaluating a swing option. The numerical example will show the optimal critical peak decisions.

Northeast Asia interconnection, and power flow considering seasonal load patterns

This paper presents the effects of an increase or a decrease of a power reserve by load flow calculations under seasonal load patterns of each country for the future power shortages faced by the metropolitan areas or by the southeastern area of the South Korea in North-East Asia. In these connections, the types of a power transmission for interconnection consist of the 765 kV HVAC and the HVDC. In this paper, the various cases of the power system interconnections in Far-East Asia are presented, and the resulting interconnected power systems are simulated by means of a power flow analysis performed with the PSS/E 28 version tool. The power flow map is drawn from data simulated and the comparative study is done. In this future, a power flow analysis was considered to reflect the effects of seasonal power exchanges. And the plan of assumed scenarios was considered with maximum or minimum power exchanges during summer or winter in North-East Asia countries.

Development of algorithm for day ahead PV generation forecasting using data mining method

In this paper, we develop an algorithm for PV(Photo Voltaic) generation forecasting on the day before. In this algorithm, we build database of solar radiation patterns by analyzing past 5 years data from the weather center but deal with February data only. Therefore, we can estimate the amount of PV power generation forecasting in February from this algorithm. This algorithm will facilitate the renewable energy development and give useful information for RES providers to manage their RES power generation schedule. We hope our proposal could help the PV module providers effectively manage their PV generation plan.

Compressed Air Energy Storage Units for Power Generation and DSM in Korea

In this paper, we discuss compressed air energy storage (CAES) units, and reflect on a demand-side management (DSM) technique including six generic load shape objectives in the Korea electric power corporation (KEPCO). The CAES technology has been considered for substitute energy utilization not only in regards to the management of large or small loads but also for use by emergency generators during a power failure. Recently, in the energy storage field, countries with CAES have developed small, medium and large units for storage roles. These units can be used for the dual-purpose applications of supplementary power generation and district heating supply systems. These units have an underground cavern or a modular-type pressurized vessel with large and small, micro containers. The storage and utilization time of the CAES are determined by the power between the lower limit and upper limit by the KEPCO load curve patterns over an entire day.

Northeast Asia interconnection, and technical & market considerations

This paper proposes technical and market considerations for the power system interconnection in Northeast Asia (NEA). In technical sides, the effects of an increase or a decrease of a power can compensate reserve power by the utilization under seasonal load patterns of each country for the future power shortages faced by the metropolitan areas or by the southeastern area of the South Korea in NEA. The transmission voltage for interconnection between South Korea and North Korea may be used 345 kV or 765 kV HVAC, and also the transmission voltage between North Korea and North China or Far-East Russia may be used 500 kV HVAC or HVDC. In market sides, we firstly deal with a monopoly electric power market, and secondly a competitive electric power market with complexity because the transition from the regulated monopoly to a free electricity market in NEA countries radically changes the situation with ISET substantiation and financing. In this paper, in the various cases of the power system interconnections in Far-East Asia, technical and market considerations are presented

Development of reliability based Demand response program in Korea

DR (Demand response) has an important role in electricity power market by reducing load quantity instead of increasing generation for balancing demand and supply. DR resources are regarded as an extra tool of balancing supply and demand in emergency condition. Also, DR resources can be used in normal condition or used for the purpose of maintaining the reserve rate. Because of the characteristics of Korean electricity market, reliability based DR programs are researched and implemented preferentially. For example, summer vacation period reduction program, DLC (Direct Load Control) and demand bidding market were operated for reliability-based DR program. This paper describes novel DR prospects for Korea considering smart grid environment. The Korean electricity community plans to transit the conventional DR system to novel DR system and decides to develop several DR reliability programs more. The novel DR system is composed of forward DR market, day-ahead DR market and real-time DR market. In this paper, time-line, information flows and the specification of proposed reliability based DR program are described briefly.

Demand response prospects in the South Korean power system

This paper describes demand response prospects for South Korea. To manage the increasing electric power demand, the way to increase power generation has reached a limit becoming a social, economic and environmental problem. To solve this problem by managing the supply side, demand response (DR) has become an important solution. As seen in other countries, the Korean electricity community plans to improve the DR in order to solve the generation problem. But the conventional DR program in Korea has a history of contracts being conducted over the transom, so the DR program has many disadvantages. This is one of the more important problems in the Korean DR program. Because of this, this paper proposes a more effective DR program than the conventional one to protect the participant returns. This paper also designs a DR the information and control structure suitable for the electrical environment.

Determination of Secondary Reserve Requirement Through Interaction-dependent Clearance Between Ex-ante and Ex-post

This paper discusses a method for the determination of frequency control reserve requirement with consideration of the interaction between ex-ante planning and real-time balancing. In proposed method, we consider the fact that the delivered energy for tertiary control reserve is determined based on required capacity for secondary control reserve and the expected amount of load errors. Uncertain load errors are derived by Brownian motion, an optimization method is suggested using a stochastic programming. In a short, we propose an interactive dependent method for determining secondary control reserve requirement based on the principle that it satisfies to minimize the total cost. As a result, this paper provides will analyze for an example model to demonstrate the capabilities of the method.