随着逆变器型资源（inverter-based resources, IBRs）占比提升，电力系统在N-1故障后的频率最低点更低，可能引发非预期的低频减载（under-frequency load shedding, UFLS）。为应对这一挑战，可对IBRs编程使其提供至少三类快速频率响应（fast frequency response, FFR），即阶跃响应、比例响应（P/f下垂响应）和微分响应（虚拟惯量）。但这些异构FFR给电力系统频率动态研究带来了困难。因此，本文提出了一种分析型频率最低点预测方法，可同时考虑IBRs提供的所有三种潜在FFR形式。该方法能快速准确地估计N-1发电跳闸故障后的频率最低点。方法基于频率最低点的闭式解，该解由考虑调速器动态和三类FFR的二阶系统频率响应模型推导得到。在含不同类型FFR的IEEE 39节点系统中的仿真结果表明，所提方法可在各种扰动下准确快速地预测频率最低点。
英文摘要：
With more inverter-based resources (IBRs), our power systems have lower frequency nadirs following N-1 contingencies, and undesired under-frequency load shedding (UFLS) can occur. To address this challenge, IBRs can be programmed to provide at least three types of fast frequency response (FFR), e.g., step response, proportional response (P/f droop response), and derivative response (synthetic inertia). However, these heterogeneous FFR challenge the study of power system frequency dynamics. Thus, this paper develops an analytical frequency nadir prediction method that allows for the consideration of all three potential forms of FFR provided by IBRs. The proposed method provides fast and accurate frequency nadir estimation after N-1 generation tripping contingencies. Our method is grounded on the closed-form solution for the frequency nadir, which is solved from the second-order system frequency response model considering the governor dynamics and three types of FFR. The simulation results in the IEEE 39-bus system with different types of FFR demonstrate that the proposed method provides an accurate and fast prediction of the frequency nadir under various disturbances.
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Generalized Nyquist Criterion Limitations and Misconceptions for Frequency Domain Stability Analysis of Inverter-based Resources Integrated Power Grids
School of Electrical Engineering and Computer Science, Washington State University（华盛顿州立大学电气与计算机工程学院）
Grid-forming inverter-based autonomous microgrids present new operational challenges as the stabilizing rotational inertia of synchronous machines is absent. The design of efficient control policies for grid-forming inverters is, however, a non-trivial problem where multiple performance objectives need to be satisfied, including voltage/frequency regulation, current limiting capabilities, as well as active power sharing and a scalable operation. We propose in this paper a novel control architecture for frequency and voltage control which allows current limitation via an inner loop, active powe…
