Estimation of Area Frequency Response in Island Operation Mode by Utilizing Interconnected Power System Measurements

This paper presents a measurement-based approach to estimate the frequency response of power system areas during island operation by utilizing measurements from the interconnected power system. The approach relies exclusively on actual measurements of previous frequency responses, eliminating the need for prior knowledge of system parameters. Initially, a mathematical relationship is established between the frequency response of the interconnected power system and that of individual areas during island operation. Subsequently, the method is applied to the Nordic power system. Prior to its application to the entire Nordic power system, particularly the Finnish power system, validation and feasibility tests were conducted using simulation models. The focus of the analysis in this study is on estimating the frequency response of the Finnish power system in island operation mode, assuming its separation from the Nordic power system. Four real disturbance events from the year 2020 in the Nordic power system were analyzed and utilized as input data. The obtained results align well with expectations for both under-frequency and over-frequency events, thereby confirming the effectiveness of the proposed method.