Quantitative Assessment Method for Grid Strength Incorporating Regulatory Effects of Power Electronic Devices

With increasing penetration of renewable energy and power electronic devices in power systems, significant changes occur in voltage dynamic behavior. In this situation, grid strength becomes significantly influenced by regulatory effects of power electronic devices, which are frequently overlooked in existing studies. To address this issue, this paper proposes a novel grid strength assessment method considering control dynamics of power electronic devices. Firstly, a dynamic model of the whole system is established, including various types of devices and the AC network connecting them. Secondly, a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$2 \times 2$</tex> transfer function matrix is calculated to quantify sensitivity of node voltage magnitude/phase to devices active/reactive power. This matrix provides a clear measure of grid strength and reflects the system's ability to maintain voltage stability under perturbations. Finally, large-scale system simulations validate the effectiveness of the proposed metric under various operating conditions.