Jae-Duck Lee

Power System Real-Time Event Detection and Associated Data Archival Reduction Based on Synchrophasors

The aim of this paper is to present methods on real-time event detection and data archival reduction based on synchrophasor data produced by phasor measurement unit (PMU). Event detection is performed with principal component analysis and a second order difference method with a hierarchical framework for the event notification strategy on a small-scale microgrid. Compared with the existing methods, the proposed method is more practical and efficient in the combined use of event detection and data archival reduction. The proposed method on data reduction, which is an “event oriented auto-adjustable sliding window method,” implements a curve fitting algorithm with a weighted exponential function-based variable sliding window accommodating different event types. It works efficiently with minimal loss in data information especially around detected events. The performance of the proposed method is shown on actual PMU data from the Illinois Institute of Technology campus microgrid, thus successfully improving the situational awareness of the campus power system network.

The PMU interface using IEC 61850

As industry develops, the complexity of power networks will increase, which will place heavier demands on their reliable management. To increase the reliability of power networks, new technologies related to the operation of smart grids and micro grids are currently under development, and various intelligent devices are applied to control and monitor power networks. PMU is a microprocessor-based intelligent measuring device that has recently been used in various field and applications because of its high-resolution data information. Its main application is in wide-area power network monitoring and control. PMU is also used in applications in the fields of fault analysis and power quality analysis. Although PMUs high-resolution data is a main advantage, its large data make its interface, IEEE C37.118, difficult to handle.. C37.118 standard is used to interface PMU. It also describes on measurement requirements, measurements, error limits, data transmission, etc. It is also used to facilitate the effective transfer of large amounts of data and to describe the measuring reference of PMU. IEC 61850 is the communication interface standard for power facilities. Although it was developed for the system interface between power facilities for substation automation, its application field is growing rapidly. The IEC 61850 standard for the PMU interface has also developed as IEC 61850-90-5. Because most intelligent power facilities will be integrated via IEC 61850 standards, the development of a PMU interface using IEC 61850 has various advantages. For the development of management systems for powerful smart grid and micro grid, applications require much information, including static and dynamic data. Because PMU is an intelligent system that can provide time synchronized dynamic data, its interface with application systems will be very helpful in the design and development of control and monitoring systems. In this paper, we describe a PMU interface using IEC 61850 standards.

A Survey on Interruption Costs of Korean Industrial Customers

An approach is often used to estimate the reliability value to determine consumers economic losses resulting from service interruptions. The quantitative estimation of interruption costs are important and meaningful work. Further the restructuring of the electric industries worldwide, most of the electric utilities and consumers have to consider the two important elements such as supply reliability and quality while calculating the related costs and the contract to sell or purchase electricity because it takes costs to keep the two elements at their higher level. Especially, the interruption or the supply reliability will have the influence on the bilateral contract between the suppliers and customers as a key point to determine the price of electric power in the competitive electric market. The increasing use of electrical and electronic machines day-by-day the electrical power supply system and the environment on the process of generation to consumption of electricity also are being changed. In other words both suppliers and consumers of electricity are required to be responsible for their interruption costs since the monetary losses are resulted from the service interruptions. This paper addresses the analysis of interruption costs and the studies made through the direct interview with Korean industrial customers for the period of two years. It is conducted to evaluate the direct and short duration interruption costs resulting from local random electrical supply interruptions. The cost is evaluated by providing a designed questionnaire focused on the experience or the preparative actions which consumers predicted they would take. In the first phase, authors made a survey on all types of industry with 176 industrial customers and evaluated them as per standard industry classification (SIC). In that case, the evaluation data obtained are not so reasonable, because the number of sampled industries was small and the sampled industries were surveyed by being divided into 18 types. So, in the second phase the authors concentrated on only 4 types of 302 industries who have many and large sensitive loads to the short duration interruption

An Event-Oriented Method for Online Load Modeling Based on Synchrophasor Data

The objective of this paper is to present a new “event-oriented” method of online load modeling for the Illinois Institute of Technology (IIT) microgrid based on synchrophasor data produced by phasor measurement units. Several load models and their parameter estimation methods are proposed. The online load modeling process is based on an adjustable sliding window applied to two different types of load step changes. The load modeling tests and related analysis of the synchrophasor data from the IIT microgrid are demonstrated.

Development of JPEG 2000 simulator and image quality analysis on bit plane coding

JPEG 2000 is new standard and it has various useful features. Bit plane coding is JPEG 2000s new coding scheme and by using it, JPEG 2000 can provide various new additional functions like high resolutions image compression, progressive transmission and scalable coding of image, etc. Because bit plane coding is one of key functional block and it play important role in JPEG 2000, we want to analyze its effect on image quality. To do so, we developed JPEG 2000 simulator including forward and inverse transform block, bit plane coding block, Tier-2 Encoder block, etc. By using it, we analyzed JPEG 2000s characteristics, changing number of bit planes and quantization step size. In this paper, we describe on image quality analysis for JPEG 2000s bit plane coding.

Development of criteria and calculation of Korean industrial customer interruption costs

This paper presents the results of direct interview survey of Korean industrial customers conducted to evaluate the direct, short-term impacts and costs resulting from local random electrical supply interruptions. The cost is evaluated using the questionnaires authors designed, which are mainly on the experience or preparatory actions consumers predicted they would take. Economic evaluation of reliability that traditionally takes into account duration and frequency of interruption does not accurately reflect the lost value or economic impacts of industrial customer, especially large size, caused by any kind of interruption. So, to imply the substantial difference in costs incurred by different customer group, the authors apply the international standards, i.e. IEC, IEEE, of the recent classification of interruption to reflect the difference of interruption characteristics on the questionnaires for the analysis of the interruption cost.

Data logger apparatus for stray current measurement of subway and power line

In present, most of metallic structures (gas pipeline, oil pipeline, water pipeline, etc) are running parallel with subway and power line in Korea. Moreover subway system and power line make a stray current due to electrical corrosion on metallic structures. The owner of metallic structures has a burden of responsibility for the protection of corrosion and the prevention against big accident such as gas explosion or soil pollution and so on. So, they have to measure and analyze the data about P/S(Pipe to Soil) potential, amplitude of stray current, point of source of stray current and so. In this paper, results of development about data logger apparatus for measurement stray current of subway and power line are presented.

Assessment of interruption costs for commercial customers in Korea

This paper presents assessment of the interruption costs for commercial customer in Korea with customer survey methodology. When various research results are examined, assessment of direct interruption cost is much more simple. Especially, in the case of commercial customers, it is known that the assessment of direct interruption cost is more useful. Accordingly, this paper selected the customer survey method to assess the interruption cost for commercial customer in Korea considering interruption and customer characteristic.

An experimental study for the real scale impulse measurement setup of overhead distribution lines

In good conditioned laboratory, measurement of impulse voltage and current was not so complicate. But in field or real scale outdoor demonstrated overhead lines, it is not so easy, because induced high voltage shock to ground connection of instrument, distributed measuring device like HV divider and others. Also control of impulse current generator is one of the problems to get like a standard waveform. Most of all, the hardest problem is economical limitation. To get a economical measuring system, in the middle of concrete pole near to bottom but separate from ground plane, a measuring system combined with normal digital oscilloscope and ups with backup battery were installed using double shielded metallic box. And HV dividers and Rogowski coils installed and connected to oscilloscope through a hole of double shield box. And three measuring points were connected with normal control cable for connection of serial communication system. Communication structure were combined several RS485 modules and main desktop computer. To avoid HV shock from impulse current, simple switching circuit was assembled with control relays. With simple communication program and manual synchronized switching action, the measuring system was well done but data transfer speed was limited at 9600. The advantage of this measuring system is economic aspect and can be operated only 1 person minimum. This system was make good result in field condition with real scale demonstration system.

Development of a Smart Sensor System using OPC UA

In this paper, a smart sensor system using the IEC 62541 standard, which represents the international standard of OPC UA is designed and developed. OPC-UA is defined as a communication standard for smart grids and smart factories, and it extends the scope of its usage by collaborating with many other standards. Currently, most of the factories in Korea have CNCs without communication functions and are mainly used to send and receive the processed files using FTP. Therefore, a smart sensor is required to secure the data required for the configuration of the smart factory. The smart sensor manufactured in this paper can be installed independently and easily applied to the smart factory management system because the OPC-UA communication middle-ware is sitting atop of it. Later, if necessary, the manufactured smart sensor system can be used to control specific equipment.