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In Korea, high generation cost and environmental pollution are also discussed at island off-grid. In this situation, remote microgrid (MG) can be solution to solve the problems. Remote MG is small power system, which consists of renewable sources, energy storage system, and load. It is possible to reduce generation cost by introducing remote MG into island areas. KEPCO (Korea Electric Power Corporation) is also proceeding study on remote MG and doing project about remote MG. KEPCO had designed demonstration site for remote MG and constructed the site at island named ‘Geocha-Island’ which is located in south-western side of Korea. This study deals with the system design by economic evaluation. Secondly, construction of the site is introduced. Finally, operation strategy of the system is introduced.

– This paper presents the methodology for optimal design of power grid for offshore wind power plant (OWPP) and optimum location of offshore substation. The proposed optimization process is based on a genetic algorithm, where the objective cost model is composed of investment, power loss, repair, and reliability cost using the net present value during the whole OWPP life cycle. A probability wind power output is modeled to reflect the characteristics of a wind power plant that produces electricity through wind and to calculate the reliability cost called expected energy not supplied. The main objective is to find the minimum cost for grid connection topology by submarine cables which cannot cross each other. Cable crossing was set as a constraint in the optimization algorithm of grid topology of the wind power plant. On the basis of this method, a case study is conducted to validate the model by simulating a 100-MW OWF.Key Words : GA optimization, Probabilistic wind power model, Offshore su bstation, Offshore wind power grid, Submarine cable crossing†Corresponding Author : School of Electrical Engineering, Soongsil University, KoreaE-mail : jckim@ssu.ac.kr* School of Electrical Engineering, Soongsil University Korea** KEPCO Research Institute, KoreaReceived : June 9, 2915; Accepted : June 25, 2015

A new system for evaluating the voltage management errors of distribution equipment is presented in this paper. The main concept of the new system is to use real distribution live-line voltage to evaluate and correct the voltage measurement data from distribution equipment. This new approach is suitable for a new Distribution Management System (DMS) which has been developed for a distribution power system due to the connection of distributed generation growth. The data from distribution equipment that is installed at distribution lines must be accurate for the performance of the DMS. The proposed system is expected to provide a solution for voltage measurement accuracy assessment for the reliable and efficient operation of the DMS. An experimental study on actual distribution equipment verifies that this voltage measurement accuracy assessment system can assess and calibrate the voltage measurement data from distribution equipment installed at the distribution line.

A microgrid is a micro-power system composed of local distributed generators, energy storage systems, loads, and other components in a local power network. Because renewable energy sources show relatively large output power variation, the integration of distributed generators in a microgrid often requires the installation of a large-scale energy storage system. The energy storage system is connected to a local AC bus via the DC/AC converter with an output inductor-capacitor (LC) filter. The energy storage system power converters generally form the local AC bus voltage. This grid-forming operation requires fast and robust voltage control to properly maintain a stable energy flow and high power quality in the local AC bus. In this paper, two major voltage control schemes—double-loop control and direct voltage control—are analytically compared, and their effects on the power quality of the microgrid are illustrated. The dynamic performance is compared through simulations and experimental results.

An Offshore wind power system is very expensive and different from that of onshore in many ways. There has been a continuous increase in the capacity of the offshore wind farms (OWFs). It is essential to analyze the availability and reliability to optimize the redundancy of OWFs. This paper presents a probabilistic reliability evaluation to determine the number of transformers and that of capacity on offshore AC substation. The proposed approach is based on probabilistic model of wind energy that combines the wind speed with output characteristics of the wind turbines and the overall economic cost model. The economic evaluation is applied to actual wind speed at the southwestern coast of the Korea and their application results are suggested.

This paper presents the application of a superconducting fault current limiter to energy storage for protection in a power distribution system. An energy storage system is increasingly being used to help renewable energy resources integrate into the grid. It is important to keep an energy storage system interconnected with the grid without interruption and to supply electrical power to the grid. The main objective of this paper is to introduce a superconducting fault current limiter to keep the energy storage system from disconnecting from the grid when ground faults occur. Its effect is analyzed using transient simulation software.