Sangwook Han

Identification of a novel pathogen-induced gene encoding a leucine-rich repeat protein expressed in phloem cells of Capsicum annuum

The CALRR1 gene, expressed in pepper leaves following infection by Xanthomonas campestris pv. vesicatoria, encodes a secreted leucine-rich repeat (LRR) with five tandem repeats of a 24-amino-acid LRR motif. Northern blot analyses revealed that CALRR1 is not constitutively expressed in pepper plants, but is strongly induced upon the infection by X. campestris pv. vesicatoria, Phytophthora capsici, Colletotrichum coccodes and Colletotrichum gloeosporioides on leaves. CALRR1 was not systemically induced in upper leaves by bacterial infection. The inoculation of bacterial live cells, and treatment with dead cells and culture filtrates of pathogenic or nonpathogenic bacteria triggered the accumulation of CALRR1 transcripts. Treatment with signaling molecules, including salicylic acid (SA), ethylene (ET), methyl jasmonate (MeJA), dl-beta-amino-n-butyric acid (BABA) and benzothiadiazole (BTH), did not activate the transcription of the CALRR1 gene, indicating that CALRR1 expression is not regulated by defense signaling pathways activated by these molecules. CALRR1 was induced by treatment with high salinity, abscisic acid (ABA) and wounding, but not by drought and cold stress. An in situ hybridization study showed that CALRR1 mRNA was localized in phloem tissues of leaves, stems, and green fruits of pepper plants during the pathogen infection and ABA exposure. The location characteristics and the spatio-temporal expression pattern of CALRR1 suggest that it may play a role in protecting phloem cells against biotic and abiotic stresses affecting phloem function.

Study of the Effectiveness of a Korean Smart Transmission Grid Based on Synchro-Phasor Data of K-WAMS

Recent technological achievement in areas of distributed computing, networking, high speed communications and digital control, as well as the availability of accurate GPS time source, are rapidly becoming the enabling factors for the development of a new generation of real time power grid monitoring tools. KDN (Korea electric power Date Network Co.) R&D department with KERI, Korea University and LSIS has embarked on long term research and development work in the field of wide area systems specifically applied to the power transmission grid in Korea. Primary focus will be on wide area measurement and monitoring, analysis, assessment technique and tools aimed at preventing the propagation of power grid instabilities. Of special interest are voltage stability and small signal stability. This project aligns with KEPCO (the Korea Electric Power Company). In this paper, case studies performed with the use of the developed system are presented.

Development of voltage stability index using synchro-phasor based data

Through the development of phasor measurement units (PMU), various aspects of power system dynamic behavior could be monitored and diagnosed. Monitoring dynamic voltage stability becomes one of achievements we can obtain from PMUs. It is very important to select the method appropriate to the KEPCO system since there are many voltage stability indices. In the paper, we propose an advanced WAVI (Wide Area Voltage Stability) for monitoring dynamic voltage stability. It reflects the PMU installation plan of KEPCO, thus it is suitable for KEPCO system specially. The salient features of the proposed index are; i) it uses only PMU measurements without coupling with EMS data. ii) it is computationally unburden so that it can be applied to real-time situation. The proposed index is applied to the KEPCO test system and the result shows that it successfully predicts voltage instability through the comparative studies.

Measurement-based Static Load Modeling Using the PMU data Installed on the University Load

Load modeling has a significant influence on power system analysis and control. In recent years, measurement-based load modeling has been widely practiced. In the load modeling algorithm, the model structure is determined and the parameters of the established model are estimated. For parameter estimation, least-squares optimization method is applied. The model parameters are estimated so that the error between the measured values and the predicted values is to be minimized. By introducing sliding window concept, on-line load modeling method can be performed which reflects the dynamic behaviors of loads in real-time. For the purpose of data acquisition, the measurement system including PMU is implemented in university level. In this paper, case studies are performed using real PMU data from Korea Univ. and Seoul National University of Science and Technology. The performances of modeling real and reactive power behaviors using exponential and ZIP load model are evaluated.

Real Time Wide Area Voltage Stability Index in the Korean Metropolitan Area

Through the development of phasor measurement units (PMU), various aspects of power system dynamic behavior could be monitored and diagnosed. Monitoring dynamic voltage stability has become one of the achievements we can obtain from PMUs. It is very important to select the most appropriate method for the Korea Electric Power Corporation (KEPCO) system since there are many voltage stability indices. In this paper, we propose an advanced WAVI (Wide Area Voltage Stability) that is well suited for the purposes of monitoring the dynamic voltage stability of KEPCO’s PMU installation plan. The salient features of the proposed index are: i) it uses only PMU measurements without coupling with EMS data; ii) it is computationally unburdened and can be applied to real-time situations. The proposed index is applied to the KEPCO test system and the results show that it successfully predicts voltage instability through comparative studies.

Voltage stability monitoring using PMU data in KEPCO system

Kepco has installed PMUs at three of its major transmission lines in 2009. An advanced algorithm, WAVI(Wide Area Voltage stability Index), has proposed in order to monitor the real-time voltage stability in metropolitan area of Korea. This paper presents a brief summary of the installation planning and provides details on results from the real-time measured data, which are obtained from those PMUs. Monitoring strategy and future plans of the PMU installation and the control system research are discussed.

Field Implementation of Voltage Management System (VMS) into Jeju Power System in Korea

This paper presents the results of field tests on Voltage Management System (VMS) using hybrid voltage control, which utilizes coordinated controls of various reactive power resources such as generators, FACTS and switched shunt devices to regulate the pilot bus voltage in a voltage control area. It also includes the results of performance test on RTDS-based test bed in order to validate the VMS before installing it in Jeju power system. The main purpose of the system is adequately to regulate the reactive power reserve of key generators in a normal condition with coordination of discrete shunt devices such as condensers and reactors so that the reserves can avoid voltage collapse in emergency state in Jeju system. Field tests in the automatic mode of VMS operation are included in steady-states and transient states. Finally, by the successful operation of VMS in Jeju power system, the VMS is proved to effectively control system voltage profiles in steady-state condition, increase system MVAR reserves and improve system reliability for pre- and post-contingency.

Wide area monitoring system for the Korean smart transmission grid using PMUs

About 42% of total of power system loads are massed in the metropolitan area in the Korean power system, but there are only about 20% of total generations in high cost. In addition, most generators are located in the nonmetropolitan area in low cost. Thus, most power transfers non-metropolitan area to metropolitan area, through the several interface lines. There are six major transmission lines, which are composed of two routes of 765kV transmission lines and four routes of 345kV transmission lines. The interface flows are limited by the voltage stability. In other words, the voltage stability is mostly influenced by those six transmission lines. So, it is necessary to monitor those six interface lines in real-time for monitoring the voltage stability in the point of view of Korean smart transmission grid.

Research on a Development of Power System Analysis Software Considering User Convenience

Abstract - Power system engineers use power systems solution programs such as PSS/E, DSATool, Power World simulators for power system analysis. In this reason, KEPCO has begun to develop independent power system program, KW-PSS(KEPCO World Power system Solution) since 2002 and KW-PSS ver2.0 development was completed in 2011. However, it did not have much better functions compared with other programs. Therefore, we focused on the development of the practical and specialized functions. Consequently, PAZ(Power system AnalyZer) ver3.0 has been developed and it realized a differentiation than previous version. In other words, previous version focused on the basic function of power system analysis, PAZ ver3.0 has implemented many automated functions for power system operators were driven maximize operational efficiency. The unique feature of the implementation is as follows : Automated check for exceeding the breaker capacity, Scheduled outage automation, Control-file wizard for various voltage stability analysis, Scenario-based multiple transient stability analysis and Auto calculation of transmission line impedance. As shown in these functions, Those functions provide to use power system analysis easily by automation and simplification for power system engineers. We will secure national expertise through PAZ ver3.0. In addition it will be able to gain competitive edge through the steady development in the world market.Key Words : Power system analyZer(PAZ), KEPCO world power system solution(KW-PSS), Power system analysis program, KEPCO software, Power systems†Corresponding Author : KEPCO Research Institute, Korea E-mail : bkko@kepco.co.kr* KEPCO Research Institute, Korea Received : July 24, 2015; Accepted : November 24, 2015