Koo-Yong Shin

Electromagnetic interference from a three phase double circuit 765-kV test line

This paper presents the results of long-term electromagnetic interference (EMI) measurements on the bundle of 6 Cardinal conductors tested at Koreas Kochang 765-kV full-scale test line. The instrumentation and the most important features of the facilities are also described. This new 3-phase double circuit test line can be energized at line-to-line voltages up to 850 kV. The analysis of the data shows that the 6-Cardinal conductor bundle meets the radio and television interference guidelines of the Korea Electric Power Corporation (KEPCO).

Development of a New Personal Magnetic Field Exposure Estimation Method for Use in Epidemiological EMF Surveys among Children under 17 Years of Age

A number of scientific researches are currently being conducted on the potential health hazards of power frequency electric and magnetic field (EMF). There exists a non-objective and psychological belief that they are harmful, although no scientific and objective proof of such exists. This possible health risk from ELF magnetic field (MF) exposure, especially for children under 17 years of age, is currently one of Koreas most highly contested social issues. Therefore, to assess the magnetic field exposure levels of those children in their general living environments, the personal MF exposure levels of 436 subjects were measured for about 6 years using government funding. Using the measured database, estimation formulas were developed to predict personal MF exposure levels. These formulas can serve as valuable tools in estimating 24-hour personal MF exposure levels without directly measuring the exposure. Three types of estimation formulas were developed by applying evolutionary computation methods such as genetic algorithm (GA) and genetic programming (GP). After tuning the database, the final three formulas with the smallest estimation error were selected, where the target estimation error was approximately 0.03 μT. The seven parameters of each of these three formulas are gender (G), age (A), house type (H), house size (HS), distance between the subjects residence and a power line (RD), power line voltage class (KV), and the usage conditions of electric appliances (RULE).

Design of the DC ±500kV full scale transmission test line in Gochang

A HVDC test line that functions as a prototype variation was constructed in Korea, after considering the main functions and characteristics of diverse ±500kV DC transmission test line towers and the results of the analysis of the lines insulation, environment, fitting, transmission equipment, economic feasibility, and operational efficiency. The variable prototype test line has advantages in line-related researches, including in the fitting design, insulation coordination design, line construction technology and transmission equipment development, and does not require high-cost towers, unlike overseas test lines. The maximum applied voltage of the newly constructed DC test line was ±600 kV, and a measurement system was established around the line to evaluate the interference factors. Tests on various environmental characteristics will be performed to derive the optimal pole arrangement coordinates for the Korean environment, while changing the pole arrangement and height of the line using a large hoist installed at special arms in tower No. 2 and 3.

Technique to decrease the electric field intensity on conductor surface using the asymmetrical-sized conductor bundle

Corona discharges form at the surface of a transmission line conductor when the electric-field intensity on the conductor surface exceeds the breakdown strength of air. In order to decrease the electric-field intensity on the conductor surface, a new 6 conductor bundle has been studied. This bundle, asymmetrical-sized conductor bundle, consists of a large subconductor at the bottom two conductor positions in the 6-conductor bundle of each phase of the line. The electric field intensity on these two large subconductors is reduced which in turn reduces the corona noise. It is proven that the newly proposed method is a better solution for decreasing the electric- field intensity than either the conventional bundle or the asymmetric bundle proposed by EPRI(Electric Power Research Institute).

The Sag and Fatigue Properties of STACIR/AW as a High Temperature, Low Sag Conductor

In Korea, as a way to expand electric capacity in power line with increasing of electric power demand, the STACIR/AW (super thermal-resistant Al alloy conductors Al-clad Invar-reinforced) conductor are used. The STACIR/AW consists of stranded INVAR/AW wire as core material for sag control and heat-resistant Al alloy for ampacity gain which was developed to catch up with tremendous increase of electric power demand. These two different materials enable the STACIR/AW to operate at a higher temperature compared to a conventional ACSR (Al alloy Conductors Steel Reinforced) without modifications to the tower. It is generally accepted that the continuous operating temperature of STACIR/AW is 210degC which is remarkably high compared to that of ACSR, 9degC. But some case of 480 mm2 STACIR/AW (conductor named Rail) of the commercial line, there are some problems with regard to sag characteristics. This paper describes the results from a long term maximum permissible current characteristic experiment using full scale test line which is energized up to 3000 A. Also the variation of fatigue property with heat exposure in stranded conditions will be presented.

Switching Impulse Flashover Tests and Analysis for 765kV Jumper V-strings with Damaged Insulators

The 765kV transmission line will be maintained by live-line works for efficient operation. In order to maintain the 765kV transmission lines safely by live-line works, lineman has to know switching impulse flashover characteristics of the jumper V-strings with damaged insulators in advance. In order to know the flashover characteristics this paper carried out experimental flashover mockup tests for jumper V-string with damaged insulators in the outdoors. And it suggests flashover characteristics of the 765kV jumper V-strings also. The results will be used in estimating the safety of live working for 765kV transmission lines.

A Development of Reduced-scale Model to Predict of Environmental Characteristics of AC/DC Hybrid Overhead Transmission Line

To review application of HVDC (High Voltage Direct Current) transmission line to HVAC T/L in operation, reduced-scale model was designed and manufactured. The arms of model were designed to change height and interval of conductors. Electrical environmental interferences were estimated by various configuration of AC 345kV and DC 250kV T/L. The interferences such as electric field intensity and ion current density were measured and converted reduced-scale factor to full-scaled. Additionally, effects between AC and DC T/L were studied.

Magnetic Field Measurement based on JEC PT 62 10 near Power Facilities in Korea

In this work, prior measurements have been carried out of the human exposure to magnetic field near power facilities in Korea according to the measurement procedures of IEC PT62110. These measurements aim for evaluating the exposure levels by use of newly proposed IEC PT62110 of the human body to the magnetic fields on general public. For this purpose, statistical treatment has been conducted with the measured data for the uniform and non-uniform magnetic field exposure.

Comparison of Electrical-Environment Characteristics Between Two Different Types of EHV Transmission Lines

Abstract This paper represents the analysis results by comparison of characteristics on electrical environment between different EHV transmission lines, such as AN (Audible Noise), RI (Radio Interference), TVI (Television Interference), EMF (Electric and Magnetic Field). In Korea, the transmission lines with nominal voltage of 765-kV have been operating since 2002, and Hungary energized a 750-kV line in 1978. However both EHV transmission lines have different line configuration, Korea is a prime example of the first double circuit 765-kV line in the world, and Hungary has been operating one of the single circuit 750-kV.