Microgrid Development on a Small Island

 By Yun-Wei Huang, Yi-Ping Chen, Chih-Ta Tsai and, Chi-Chang Chan

Traditionally, the main supply of electrical energy in the remote small island is imported diesel fuel. The expensive costs of transportation, fuel and operation cause significant financial costs for most utilities. It is evident that a partial replacement of renewable energy on such an island reduces expenses. As the attractive renewable energy is gradually developed and may become the major energy in the island, microgrid technology must be considered to maximize the utilization of renewable energy and maintain power quality.

From an economic analysis, microgrids integrated with renewable energy, energy storage, and information communication technology efficiently achieves fossil fuel energy reductions and peak shaving, as well as reduced numbers of fossil fuel-fired generation units. The budget and ROI (return on investment) on a microgrid on a small island are practically considered and evaluated to decide the preliminary investment, including the installed capacity. The affordable solutions can be divided into only installation of renewable energy without any control, integration of renewable energy and diesel generation, integration of renewable energy and energy storage, and the coordination of renewable energy, energy storage and diesel generation.

Politically, energy independence is highly intertwined with security. One-hundred percent renewable energy is an aggressive long-term goal of energy and environmental policies. In the short term, replacement of fossil-fuel energy with renewables is a sustainable development.

The impact of increasing renewable energy penetration on the power system is a technical challenge, especially for a small island. Renewable energy, diesel generators, energy storage and load consumption are coordinated to maximize fossil fuel savings and operate more efficiently.

Itu Aba Island and Pratas Island are the most distant from Taiwan. To build up the microgrid technology in the remote small island, the economic and environmental benefits can be obviously achieved. Pratas Island, also known as the Dongsha Island, in the north of the South China Sea, is located 850 kilometers (530 miles) southwest of Taipei, Taiwan. In the past, four 500-kW diesel generators on Pratas Island were the only energy source. Based on the operating records, the annual averaged load is 150kW: 180kW in the summer and 120kW in the winter. Forty kilowatts of solar energy without energy storage is available to generate electricity, so a cost-efficient strategy for lowering fuel consumption from diesel generators is necessary. Matching solar generation and diesel generation with load consumption, efficient operation of them is paramount. A fuel-saving controller is designed to monitor and coordinate solar and diesel generation.

Itu Aba Island, also known as Taiping Island, is located 1,900 kilometers southwest of Taipei, Taiwan. It is powered by three 400-kW diesel generators, 160 kW PV, and 612 kWh energy storage. Installing monitoring and control of the diesel generators is not available because it is costly and time-consuming. Itu Aba Island is suitable for the existing diesel generator system with a passive energy storage system that has an important role in maintaining a stable power system.

For a downloadable copy of  August 2016 eNewsletter which includes this article, please visit the IEEE Smart Grid Resource Center.

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