Je-Seok Shin

Optimal Design for Offshore Wind Farm considering Inner Grid Layout and Offshore Substation Location

This paper introduces an efficient methodology to design optimally cable layout of inner grid as well as location of offshore substation. The methodology is composed of two optimizers: one is inner grid layout optimizer, which consists of several algorithms such as the k-clustering-based genetic algorithm, the minimum spanning tree, and the cable selection; the other one is offshore substation location optimizer based on the pattern search method. While performing iteratively two optimizers, alternatives for cable layout and candidates for location of offshore substation are generated and evaluated in the economic and reliability aspects, respectively. Optimal layout of offshore wind farm is determined so as to minimize the total cost which is a sum of construction, power loss, maintenance, and reliability costs.

Reliability evaluation considering structures of a large scale wind farm

Wind energy is one of the most widely used renewable energy resources. Wind power has been connected to the grid as large scale wind farm which is made up of dozens of wind turbines, and the scale of wind farm is more increased recently. Due to intermittent and variable wind source, reliability evaluation on wind farm is necessarily required. Also, because large scale offshore wind farm has a long repair time and a high repair cost as well as a high investment cost, it is essential to take into account the economic aspect. One of methods to efficiently build and to operate wind farm is to construct wind farm which is able to enhance a capability of delivering a power instead of controlling an uncontrollable output of wind power. Therefore, this paper introduces a method to evaluate the reliability depending upon structures of wind farm and to reflect the result to the planning stage of wind farm.

Operation Strategy of Multi-Energy Storage System for Ancillary Services

Energy storage systems (ESSs) used for ancillary purposes in power systems have different capacities and output characteristics, and so need to be scheduled and operated together based on their state of charge rather than individually. This paper proposes a simple but effective method to allocate the energy required for spinning reserve or frequency regulation, properly to each ESS within a multi-ESS with the aim of improving system reliability. For this, an ESS reliability model is first proposed, and the reliability of the entire system is then evaluated using reliability models for other utilities such as conventional generators and renewable energy sources. To better demonstrate the improvement in reliability, two new reliability indices are introduced besides the existing indices: loss of frequency probability and loss of duration probability. Through case studies, it is shown that the required power is more effectively distributed across each ESS by the allocation method and thus the method can contribute to securing more spinning reserve and alleviating more frequency fluctuation, rather than the conventional method.

Transmission Network Expansion Planning for the Penetration of Renewable Energy Sources - Determining an Optimal Installed Capacity of Renewable Energy Sources

Due to global environmental regulations and policies with rapid advancement of renewable energy technologies, the development type of renewable energy sources (RES) in power systems is expanding from small-scale distributed generation to large-scale grid-connected systems. In the near future, it is expected that RES achieves grid parity which means the equilibrium point where the power cost of RES is equal to the power costs of conventional generators. However, although RES would achieve the grid parity, the cost related with development of large-scale RES is still a big burden. Furthermore, it is hard to determine a suitable capacity of RES because of their output characteristics affected by locations and weather effects. Therefore, to determine an optimal capacity for RES becomes an important decision-making problem. This study proposes a method for determining an optimal installed capacity of RES from the business viewpoint of an independent power plant (IPP). In order to verify the proposed method, we have performed case studies on real power system in Incheon and Shiheung areas, South Korea.