Increasing Grid-connected Capacity of Offshore Wind Farms for Isolated Power Systems-A Case Study of the Taiwan Power System

Abstract

In response to the development of Taiwan’s renewable energy policy in recent years, efforts have been made toward promoting energy transformation to reduce the generation of thermal and nuclear power as well as power generated by other traditional machine units, with the ultimate goal of increasing renewable energy generation. Among all types of electricity generation, offshore wind power has gradually progressed and become the focus of renewable energy development in various countries. According to the current policy, offshore Taoyuan, Miaoli, Changhua, and Yunlin were selected as installation sites for offshore wind farms. In addition, seaside distribution substations were constructed to serve as connection points for offshore wind farms. Buses with a voltage of 161 kV were connected to the network in centralized, evenly decentralized, and load rate settings. First, the maximum grid-integration capacity of the system, identified without the addition of additional lines and on the basis of N-1 accidents, was compared with the plans and objectives of Taiwan Power Company for 2025. The simulation results indicated that if no additional transmission line is added, congestion occurs in regional transmission lines, which limits the grid-integration capacity of offshore wind power farms, thereby failing to meet the goal of achieving 5.5 GW of offshore wind power capacity set by the government for 2025. In this study, simulation was conducted in Changhua by using three search methods for installing transmission lines to determine the optimal point for adding additional transmission lines, thereby resolving the problem of congestion in regional transmission lines and improving the grid-connection capacity. Simulation results revealed that the addition of three transmission lines meets the goal set by the government as well as resolves line congestion. Finally, the advantages and disadvantages of the three search methods were compared. The comparison results may facilitate the integration of offshore wind farms into the power system in Taiwan and serve as reference for system installation and improvement.