Chan-Eom Park

Sensor value validation based on implicit sensor redundancy for reliable operation of power plants

This paper presents an innovative sensor value validation technique that can systematically explore the embedded sensor redundancies in power plants and utilize them in validating sensor values. The proposed technique uses the relationships existing among the sensor values, which is called causal relations (CRs) in this paper. A data structure called a sensor redundancy graph (SRG) is formulated to explore systematically the sensor redundancies existing throughout the plants. In the SRG, CRs are represented as nodes and two CRs having a common sensor are connected with an edge. The criteria are also provided for testing whether a given sensor relationship expressed as a CR holds with the actual measurement values. If the relationship holds, the necessary condition for the validities of the sensors participated in the CR is satisfied. A technique that can examine the compatibility of the precisions among the sensors in a CR for testing the usability of the given CR is also developed based on sensor precision indices and statistical inference. The proposed technique is applied to flow meter data provided from an actual super critical steam power plant and its application potential is demonstrated.

An Assessment on Harmonics Effect in Customer and the Distributed Power System during Grid Connection of Residential Fuel Cell System

Recently, due to the use of fossil fuels for electric power production, carbon emissions increased excessively. Thereby, in order to replace fossil fuels, many studies about fossil fuels such as solar and fuel cell energy source are progressing. Fuel cell system has high energy conversion efficiency. Also, fuel cell system is environmentally friendly system because the carbon emission is almost not occur. Therefore, the fuel cell system is considered as the core technology of in the fields of the future energy and environmental. Fuel cell system has an effect on distribution power system because another power source of other than large power plants. So, fuel cell system can be degradation reason of power quality in the power system. In this paper, we constructed the system for an assessment on harmonics effect. The system is composed with power source, harmonics generation and linear load, fuel cell system. we also performed assessment on harmonics effect in customer and the distributed power system during grid connection of residential fuel cell system. An assessment cases are divided into three. A Case 1 is state that residential load and fuel system are connected to grid, Case 2 is state that residential load and harmonics load are connected to grid, and Case 3 is state that all loads are connected to grid. As a output of fuel cell system is increase, analysis results based on assessment system showed that power quality became more aggravation as effect of harmonics.

Correlation Analysis about Loop Impedance and Load Condition

This paper presents a loop impedance(inner loop impedance & external impedance) measurement method in TN system. When the measurement of a loop impedance then the measurement result have a some error by load condition. In this paper suggest the loop impedance measurement on actual loading condition by two experiment. one was laboratory condition and the other was the actual measurement on site. Analysis result, measuring error by load condition has not effect on measuring loop impedance.

Development of Arc-Fault Detection Technique

Abstract In 2007, 9,128 fires were actually caused by electrical faults and these fires resulted in 29 deaths and 262 injuries. Arc-faults were one of the major causes of these fires. When an unintended arc-fault occurs, it generates intense heat that can easily ignite surrounding combustibles. But, because conventional circuit breakers only respond to overloads, short circuits, and leakage currents, the breakers do not protect against arcing conditions. This paper presents results obtained in experiments on ignition behavior of wire by series arc fault currents and techniques developed to detect the arc-faults. The developed technique was tested after installation to make sure that they are working properly and protecting the circuit. If the developed arc fault detection technique is applied, the electrical fires caused by an arc-fault can be reduced. Key Words : Series Arc, Electrical Fire, Arc Detection Algorithm 본 논문은 지식경제부 전력산업기반기금으로 수행되었음. * 교신저자 : 임용배(electrotree@gmail.com)접수일 09년 06월 22일 수정일 (1차 09년 08월 12일, 2차 09년 08월 17일) 게재확정일 09년 08월 19일

An Assessment on Voltage and Power Quality in Load Facility during the Islanding of Residential Fuel Cell System

Recently, due to the excessive use of fossil fuels, many studies about the fossil fuels such as solar and fuel cell energy source are progressing. Fuel cell system has high energy conversion efficiency. Also, fuel cell system is environmentally friendly system because the carbon emission is almost not occur. Therefore, the fuel cell system is considered as the core technology of in the fields of the future energy and environmental. Fuel cell system has an effect on distribution power system because another power source of other than large power plants. So, fuel cell system can be reason of power quality in the power system. In this paper, we constructed the system for an assessment on Islanding. The system is composed with power source, Impedance coordination load and linear load, fuel cell system. we are performed assessment on voltage and power quality in customer and the distributed power system during the Islanding of residential fuel cell system. In addition, no change in the impedance of power system, we made a islanding condition only using the actual load, As a variation of generation and load current under islanding, an analysis results based on assessment system showed that the power qualities of distribution system became more aggravation as effect of voltage sag and voltage swell phenomena.

The Study About Low Voltage Circuit Breaker Mix Method Between IEC Circuit Breaker and Domestic Circuit Breaker

Recent WTO/TBT agreement was adopted by the IEC domestic. For this reason, low voltage electrical equipment was many Confusion arises. Low voltage circuit was also one of these. The case of low voltage circuit, existing domestic circuit breakers and circuit breakers IEC curve differs from the behavior of each other. If low voltage circuit breaker wrong facility, circuit breaker malfunction may occur due to the large property damage. In this paper, to solve these problems domestic circuit breakers and circuit breaker operation IEC curves were analyzed. And, through experiments suggested compatible breaker way.

A Plan for Construction of the National Electrical Safety Grid to Prevent the Fires Caused by Electrical Faults

In this paper, in order to monitor and manage an electrical risk factor like as leakage current, load current, and arc-fault, a real time monitoring and management system being operated in the ubiquitous environment was developed, and a plan of construction of an electrical safety grid using the system was proposed. For confirmation of usefulness and reliability of the proposed safety system and grid, the developed intelligent panels were applied to 28 Korean traditional houses in Jeonjoo city, and the grid including the panels was operated. If the proposed National Electrical Safety Grid is completely constructed in the houses of general electrical users, the Grid will have an effect on that a main manager on electrical safety transfers from management system by general people to real-time management system by expert. As a result, the electrical fires caused by an over-load, an arc-fault, and an earth-fault will be prevented.

A Study of Autonomous Intelligent Load Management System Based on Queueing Model

This paper presents an innovative load management technique that can effectively lower the summer peak load by adjusting the aircondition loads through smoothe coordinations between utility companies and large customers. An intelligent hierarchical load management system composed of a Central Intelligent Load Management System(CIMS) and multiple Local Intelligent Management Systems(LIMS) is also proposed to implement the reposed technique. Upon receiving a load curtailment request from the utilities, CIMS issues tokens, which can be used by each LIMS as a right to turn on the airconditioner. CIMS creates and maintains a queue for fair allocation of the tokens among the LIMS demanding tokens. By adjusting the number tokens and queue management Policies, desired load factors can be achieved conveniently. The Markov Birth and Death Process and the Balance Equations are employed in estimating various queue performances. The proposed technique is tested using a summer load data of a large apartment complex and proved to be quite effective in load management while minimizing the customer inconveniences.

A Capacity Estimation Technique of Solar-Wind Hybrid Power System for an Urban Residential Load

Abstract In this paper a technique that can estimate the required capacity of a Solar Wind Hybrid Power(SWHP) system for an unban residential load is presented. The probability distribution of the power output from SWHP system is calculated from the probability density functions(PDFs) of the solar irradiance and the wind speed for each hour. The size of photovoltaic(PV) array and the number of wind turbines are decided so that the total SWHP system output in one day can meet the total daily residential-load. The available power for battery system charging can be obtained from the difference between the SWHP system generation and the load. Consequently, the distribution of the battery charging power is calculated by convolving the PDFs of both the SWHP system output and the load. A typical local residential load curve is used for illustration and promssing result is obtained.