Impedance-Based Online Estimation of Nodal Inertia and Primary Frequency Regulation Capability

Abstract

Accurate estimation of inertia and primary frequency regulation (PFR) capability is important to ensure frequency stability in low-inertia power systems. This paper investigates how the inertia and PFR capability of a power source node can be evaluated using a non-invasive online estimation method from the impedance perspective. Based on small perturbation injection, a novel approximate relationship between the impedance and corresponding frequency response transfer function (FR(s)) is deduced. The features of the FR(s)&#x2019;s magnitude response curve, i.e., resonance frequency and DC gain, are then used to develop an overall implementation framework for nodal inertia and PFR capability estimation in real time. This method provides new insights with respect to obtain the synchronous and non-synchronous converter interfaced generator&#x0027;s inertia constant and PFR capability for grid operators via impedance calculation and measurements. Case studies on a modified 9-bus system and NETS-NYPS 68-bus system demonstrate the effectiveness of the proposed impedance-based estimation approach.<fn id="fn4" fn-type="other"> This work was supported in part by the National Natural Science Foundation of China (52077066), in part by the Hunan Provincial Natural Science Foundation for Excellent Young Scholars (2020JJ3011), and in part by the Huxiang Young Talents Science and Technology Innovation Program (2020RC3015). (<i>Corresponding author: Yunfeng Wen</i>) W. Zhang and Y. Wen are with the College of Electrical and Information Engineering, Hunan University, Changsha 410082, China (e-mail: ; ). C. Y. Chung is with the Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China (e-mail: C.Y.). </fn>