Jin-Boo Choo

Comparison of transient stability analysis and large-scale real time digital simulation

The KEPS Real Time Digital Simulator (RTDS/sup (R)/) is the largest real time power system simulator ever built. A power system which includes 320 (3-phase) buses and 90 generators has been modeled and run in real time. Since such large-scale systems were involved, it was not practical to validate them using nonreal time electromagnetic transient programs such as EMTDC/sup TM/ or EMTP. Instead, the results of the real time electromagnetic transient simulation were validated by comparing transient stability simulations run using PTIs PSS/E/sup TM/ program. The comparison of results from the two programs were in almost all cases very good. However, as expected, some differences did exist and were investigated. The differences in the results were primarily traced to the fact that the electromagnetic transient solution algorithm provides more detail and therefore greater accuracy than the transient stability algorithm. After finding very good comparison of results between the RTDS Simulator and PSS/E, and after investigating the discrepancies found, KEPCO gained the necessary confidence to use the large-scale real time simulator to analyze and develop their power system.

Verification of Hybrid Real Time HVDC Simulator in Cheju-Haenam HVDC System

Abstract In this paper Hybrid Real Time HVDC Simulator for both operators training and researching in Cheju-Haenam HVDC system is proposed and its performance is verified by RTDS(Real Time Digital Simulator), EMTDC(Electro-Magnetic Transient system for DC), PSS/E(Power System Simulator for Engineering), and experienced scenarios. The main objective of this paper is to represent the strategy in development of the KEPCO hybrid HVDC simulator for Cheju-Haenam HVDC system. This simulator consists of two DC stations, DC cables, external digital/analogue controllers, control desk for education, and AC networks. In cases of both startup/shutdown and normal state operations, the suitability of it for operators education is tested. Also the dynamic performances of it are verified.

Development of Wide Area Monitoring System Using GPS

Abstract This paper describes the development of a wide area monitoring system(WAMS) and on-line transient stability monitoring tools. The master system ofthe WAMS at the Control Center monitors the important system conditions transmitted from 8 local measurement units installed at major generating stations and substations. Each local unit can measure two 3-phase bus voltages and 3-phase currents offourteen feeders at the 7,680 Hz sampling rate, and measured data are transmitted to the master system 10 times per one second.

Modelling and Analysis of Faults in Wind Power

This paper deals with the transient performance of induction generator in wind power plant. Induction generator and grid equipments may be damaged when a sudden disturbance occurs, for example, like a sudden disconnection from the utility grid. The reasons of this are due to over-voltage and over speed. This paper analyzed this phenomena using PSCAD/EMTDC and coincides with mathematics equation

Hybrid simulator of Cheju-Haenam HVDC system and its dynamic performance study

This paper deals with the development of the simulator Cheju-Haenam HVDC system and its dynamic performance study and verify the control characteristics of the HVDC system. It discusses the simulator development requirement and criteria. It provides guidelines for developing the simulator and presents the results of the simulator

Torsional stress of turbine-generator in power system with an HVDC

Abstract This paper deals with the impact of an excitation system on the torsion dynamics of turbine-generators, which are located on the inverter side of HVDC systems. Turbine-generator stress depends on the type and the parameters of an excitation system, and the fault type and location in an AC network because of commutation failures at the inverter station. Also, this paper analyzes how parameters of an excitation system are related to the torsional stress of a turbine-generator. Using the CIGRE benchmark model, the torsional stress on a generator on the inverter side is simulated. The PSCAD/EMTDC program is used for simulation studies.

Study of UPFC Operation Strategies in KEPCO System(I)-Steady State Characteristics

Abstract This paper presents a study performed to investigate steady-state operational strategies of UPFC in the Jeollanam-Do system in Korea. The objective of the study was to determine the UPFC operating points in normal and contingency conditions. The study consists of developing load flow models to simulate different load levels with and without UPFC in the system, assessing the effectiveness of UPFC by contingency analysis, and introducing corrective actions by optimization for removing voltage problems caused by contingencies. The paper describes analytical tools, model and approach. It also includes analysis and discussion of the study results. The paper contributes to the area of transmission operational studies with FACTS applications.

Determination of Synchronous Machine and Excitation Systems Parameters from Field Tests

Abstract This paper describes the generator and excitation system parameters derived from the dynamic and steady state field tests. The load rejection tests to obtain synchronous generator parameters are performed by sustaining the unsaturated and constant field voltage when the generator circuit breaker is opened. To determine excitation system parameters, by injecting the step input to AVR reference under generator running at the rated speed, ceiling voltage and AVR limit ofexcitation system can be measured and detemtined. The parameters of the synchronous generator and excitation system can be deterrnined by these field tests.

A Study on the Algorithm and its Practical use for Improving the Reliability of Automatic Power Restoration System

Abstract Recently, according to a rapid increase of the power demand, the I 54kV lines of Korea Electric Power Corporation (KEPCO) are continuously expanded and become to the more complex loop system. As a result of increase of the fault capacity and the unbalance of power load flow, the circuit breaker have been exceeding the capacity limit of those in the loop power system. To solve this problem, this paper presents algorithm and application of Automatic Power Restoration System (hereafter called APRS)

Study Of UPFC Operation Strategies in KEPCO System(II)-Dynamic Characteristics

Abstract Korea Electric Power Corporation (KEPCO) has installed an 80 MVA Unified Power Flow Controller (UPFC) at its 154kV Kang-Jin Substation in South Korea. The device, manufactured by Siemens & Hyusung, has been operational since Oct. 2002. The Korea Electric Power Research Institute (KEPRI)), a division of KEPCO was tasked to study the operation strategies that could be employed for the UPFC and surrounding reactive support devices to address problems of low voltages and overloads in the Mokpo & Gwangju areas forsevere contingencies. A special concern involved potential delay in the installation of a new 345 kV transmission line from 2005 to beyond 2010. The studies were to determine if these problems could be eliminated by UPFC application. The studies included determining the UPFC operating point under the various conditions, investigations of the coordination between the UPFC and a HVDC line terminating in this area, and to design the supplementary damping controller for the UFPC. This paper summarizes the results of those studies, demonstrating the dynamic characteristics of the operation of this UPFC operation in the Korean power system.