When a high-capacity offshore wind farm (OWF) is connected to a power system, the power quality of the power system can be significantly deteriorated under various wind speeds. This paper presents the analyzed voltage variations of Taiwan Power System connected with a 100-MW OWF using a commercial power system simulation software. The ultrahigh voltage bus of ten onshore substations that are close to the potential OWF is selected as the connection point. The voltage variation results at the connection points under different lengths of submarine cable are accomplished and analyzed when the 100-MW OWF is connected to the selected substations. The simulated results can offer a reference for the development of OWFs in Taiwan in the near future.