Seungmin Jung

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.

A Study on Peak Power Reduction using Regenerative Energy in Railway Systems through DC Subsystem Interconnection

Owing to the consistent increase in energy efficiency issues, studies for improving regenerative energy utilization have been receiving attention in the Urban DC railway systems, where currently, the utilization of regenerative energy is low due to the lack of a specific plan for using this energy. The regenerative energy in railway systems has a low efficiency problem which results in the increase of the catenary voltage and a possibility to create problems to the electrical devices connected to the system. This paper deals with the power integration of large urban railway subsystems to improve regenerative energy utilization where the railway subsystems are integrated with other railway subsystems to improve the energy efficiency. Through the case studies, to find the realistic effect of integrated operation, the Seoul Metro subsystems, namely Line 5 and Line 7, has been applied. Also, evaluation for the electricity cost saving has been performed by using KEPCO electricity cost table.

A Study of Improving Regenerative Energy Utilization in Urban DC Railway Systems Through Sharing Substations

This paper deals with the power integration of large urban railway systems to improve regenerative energy utilization. Current regenerative energy utilization is low because there is no special plan for using this energy. If the railway system is integrated with other railway systems, the efficiency is expected to be improved. Through the case studies, to find the realistic effect of integrated operation, real system for the Seoul Metro lines, especially line 5 and 7, had been applied.

System reliability enhancement in a metropolitan area using HVDC technology

Recently, due to the increase of massed demand areas, in terms of system reliability has been raised several issues such as voltage, frequency problems and fault current. In Korean power systems, more than 40% of the total loads are concentrated in metropolitan areas, however most large plants are located in non-metropolitan areas. In these long-distance transmission systems, the transmission capacity is limited not by thermal capacity constraint, but by stability constraint. To solve these problems, the study of enhancing power system stability and increasing transmission capacity has been progressed. In this paper, we analyse domestic power systems in order to discuss the best solutions for current reduction using PSS/E simulation. Fault current problems can be resolved through gird segmentation which adopts Voltage Sourced Converter Back-to-Back High Voltage Direct Current (VSC BTB HVDC). Furthermore, grid segmentation can enhance the interface flow margin with the independent reactive power control in...

A Study About Grid Impose Method On Real-Time Simulator For Wind-Farm Management System

Owing to the variability of large-scaled wind power system, the development of wind farm management technologies and related compensation methods have been receiving attention. To provide an accurate and reliable output power, certain wind farm adopts a specified management system including a wind prediction model and grid expectation solutions for considering grid condition. Those technologies are focused on improving the reliability and stability issues of wind farms, which can affect not only nearby system devices but also a voltage condition of utility grid. Therefore, to adapt the develop management system, an expectation process about voltage condition of Point of Common Coupling should be integrated in operating system for responding system requirements in real-time basis. This paper introduce a grid imposing method for a real-time based wind farm management system. The expected power can be transferred to the power flow section and the required quantity about reactive power can be calculated through the proposed system. For the verification process, the gauss-seidel method is introduced in the Matlab/Simulink for analysing power flow condition. The entire simulation process was designed to interwork with PSCAD for verifying real power system condition.

Peak power measurement and substation capacity calculation for DC On-Line Electric Vehicle system

Studies for improving charging efficiency and charging mechanisms have been receiving attention for electric transportation systems. An On-Line Electric Vehicle (OLEV) system which utilizes a DC power system is addressed for reducing the loss and peak power consumption. It is necessary to calculate the power flow analysis considering the unique characteristics of OLEV for the commercialization of this new transport system. The DC OLEV power system is implemented for reducing line losses and peak power, thereby reducing the electric cost levied on the substation. In this paper, the analysis process has been carried out regarding the shortcomings of the present AC OLEV system, and focused on providing solutions by configuring a DC OLEV system. Furthermore, verification processes are performed through simulation for various scenarios to examine the effectiveness of the proposed system in terms of power consumption, peak power, and facilities capacity.