Chong Suk Song

Optimal Operation Plan of the Online Electric Vehicle System Through Establishment of a DC Distribution System

Owing to the consistent increase in energy efficiency issues, studies for improving the charging efficiency and energy density of batteries have been receiving attention in the electric vehicle transportation sector. This paper deals with an online electric vehicle (OLEV) system which utilizes the dc power system for reducing loss as well as reducing the size of the required battery capacity. Intensive research on grid integration with OLEV has not been performed until recently and it is necessary to calculate the power flow analysis considering the unique characteristics of OLEV for the commercialization of this new transport system (for the application of this new system in the transport sector). In this paper, the dc OLEV power system is being investigated for reducing line losses and peak power thereby reducing the electric cost levied on the substation. Verification processes are performed through simulation for various scenarios to examine the effectiveness of the proposed system in terms of power consumption, battery state of charge, peak power, and loss reduction.

Implementation of PTDFs and LODFs for Power System Security

Distribution factors, which are linear approximations of the sensitivities of the system variables for changes in the power injections or any events in the system, play an important role in the security analysis and market applications. Cascading faults, which are triggered by the overloading of lines due to a fault has been the major issue deteriorating the reliability of the power system thereby requiring measures to revert the power flow on overloaded lines. This paper proposes an algorithm, by utilizing the formulation of PTDFs and LODFs, to calculate the generation shifts so that the power flow on the transmission lines that violate security limits due to single and multiple-line outage events are adjusted to its security limits. This methodology is being tested on the IEEE New England 10-generator 39-bus system for effectiveness.

Study on Jeju Island power system considering multiple HVDC

Jeju Island, which is the largest island in Korea, has an electric system which has special characteristics where a portion of the required electricity is being provided from the mainland through HVDC lines controlled by the frequency mode. Also, owing to its abundant wind resources, it is favorable for the installation of large scale wind farms with some already being operating and many under construction. Furthermore, the island which has been selected for the Smart Grid test bed will involve generation and power system infrastructure utilizing various renewable sources being tested at the site. Owing to the increase in the load demand and increase in the stability of the island system, the second HVDC line is under construction. This paper deals with the analysis of the 2013 power system of Jeju Island with the inclusion of the wind farms and multiple HVDC to examine the stability of the island system. Several contingency cases are being simulated to form an optimal operational strategy for the operation of the two HVDC lines.

A New Assessment for the Total Harmonic Contributions at the Point of Common Coupling

A new method to determine the total harmonic contributions of several customers and the utility at the point of common coupling is presented. The proposed method can quantify the individual harmonic impact of each suspicious harmonic source at the point of common coupling. The individual harmonic impact index is then used to assess the total harmonic contribution of each harmonic source. This index can be calculated by the results processed from instantaneous harmonic voltage and current phasor values. The results demonstrate the performance of the proposed method in terms of steadystate accuracy and response to time-varying operating conditions. The proposed index can be used for billing purposes to control harmonic distortion levels in power systems.

Novel Protection Scheme With the Superconducting Power Cables and Fault Current Limiters Through RTDS Test in Icheon Substation

This paper proposes a novel power system protection scheme in the power system including high temperature superconducting cables (HTS cables) and high temperature superconducting fault current limiters (HTSFCLs). The superconducting power system utilizes the large-capacity and environment-friendly characteristics of superconducting power equipment. Since the superconducting devices are one of the most optimal solutions to enhance the robustness of the power system, especially in Icheon substation in Korea, the protection of the conservative relays and additional relays, differential and instantaneous overcurrent relays, should be alternated with a new optimal protection coordination under the changed system configurations. To find the optimal protection scheme, the power system with existing power devices, conservative relays, HTS cables, and fault current limiter has to be modeled in Icheon substation and the novel protection scheme has been verified through RTDS test with real-time relay test.

Visualization of Dynamic Simulation Data for Power System Stability Assessment

Power system analyses, which involve the handling of massive data volumes, necessitate the use of effective visualization methods to facilitate analysis and assist the user in obtaining a clear understanding of the present state of the system. This paper introduces an interface that compensates for the limitations of the visualization modules of dynamic security assessment tools, such as PSS/e and TSAT, for power system variables including generator rotor angle and frequency. The compensation is made possible through the automatic provision of dynamic simulation data in visualized and tabular form for better data intuition, thereby considerably reducing the redundant manual operation and time required for data analysis. The interface also determines whether the generators are stable through a generator instability algorithm that scans simulation data and checks for an increase in swing or divergence. The proposed visualization methods are applied to the dynamic simulation results for contingencies in the Korean Electric Power Corporation system, and have been tested by power system researchers to verify the effectiveness of the data visualization interface.