Frequency selection method for urban low frequency multi‐terminal interconnected systems

Abstract

Abstract Large‐scale urban power grid (LUPG) is normally under the operating mode by voltage layer and zone partition. One of the most important directions for the development of urban is to enhance the controllability by flexible low‐frequency interconnection technology. In this study, a frequency selection method for urban low‐frequency multi‐terminal interconnected systems (ULFMIS) is proposed. Firstly, the required support power under different conditions, the index number of sending partition (SP) and receiving partition (RP) are determined. Secondly, by calculating the current distribution along the line under different support powers, the upper limit of the transmission frequency (ULTF) of each line is obtained. Finally, the smallest transmission frequency among the ULTFs of different tie lines is selected as the ULTF of the ULFMIS. The proposed method is validated in a typical four‐terminal ULFMIS. The results demonstrate that the suggested method is suitable for calculating the ULTF taking account of the influence of the number of parallel lines on economic cost and provide guidance for future practical ULFMIS projects.

Keywords

• flexible AC transmission systems
• flexible alternating current transmission system (FACTS)