arXiv subjects

Fuyilong Ma

Publications and source records attributed to Fuyilong Ma.

3 recordsLinked to original sources

arXiv2026

Revisiting Voltage and Synchronization Stability Analysis in Grid-Following Converter-Integrated Weak Grids: Insights from Non-Minimum-Phase Zeros

The increasing penetration of grid-following (GFL) converter-interfaced generators (CIGs) intensifies concerns over small-signal voltage and synchronization stability. While existing theories treat these two stability issues distinctly, practical wisdom in contrast employs a unified and static metric, short-circuit ratio (SCR), to assess both in weak grids. This paper aims to bridge this theory-practice gap by introducing the insight of non-minimum-phase (NMP) zeros. First, we demonstrate that the two stability issues in weak grids can be characterized within a common NMP-zero-based assessment framework: a zero at the origin corresponds to voltage instability, while low-frequency zeros impose fundamental constraints on synchronization dynamics. The traditional SCR is proven to be a special case of our proposed novel stability metric, NMP-zero (NMP-Z) factor, evaluated at the rated operating point. This establishes the theoretical foundation for the empirical success of SCR. Building on this insight, we then develop a unified stability assessment method for multi-converter systems. The method retains the simplicity of SCR, requiring only the NMP-Z factor together with individual CIG dynamic models and enabling stability margin assessment under various operating points. Our work provides a simple yet theoretically rigorous framework for stability analysis in CIG-integrated weak grids, with all theoretical findings and the proposed method validated through detailed time-domain simulations.

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arXiv2024

Ensuring Disturbance Rejection Performance by Synthesizing Grid-Following and Grid-Forming Inverters in Power Systems

To satisfy dynamic requirements of power systems, it is imperative for grid-tied inverters to ensure good disturbance rejection performance (DRP) under variable grid conditions. This letter discovers and theoretically proves that for general networks, synthesizing grid-following (GFL) inverters and grid-forming (GFM) inverters can always more effectively ensure the DRP of multiple inverters, as compared to homogeneous inverter-based systems that solely utilize either GFL or GFM inverters. The synthesis of GFL inverters and GFM inverters can concurrently increase the smallest eigenvalue and decrease the largest eigenvalue of the network grounded Laplacian matrix. This can be equivalent to rematching the proper short-circuit ratio (SCR) for GFL and GFM inverters, thereby ensuring the DRP of inverters both in weak and strong grids. The results reveal the necessity of synthesizing diverse inverter control schemes from the network-based perspective. Sensitivity function-based tests and real-time simulations validate our results.

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arXiv2024

Characterizing the Role of Complex Power in Small-Signal Synchronization Stability of Multi-Converter Power Systems

Small-signal synchronization instability (SSI) may be triggered when a grid-connected converter is operated in weak grids. This problem is highly related to the active and reactive power (referred to as complex power) generation or consumption of the converter. Such an instability phenomenon manifests as power oscillations within the bandwidth frequency of phase-locked loop (PLL). However, in a multi-converter power system (MCPS), it is challenging to characterize the role of each converter's complex power in SSI issues due to the high dimension of system dynamics. In this paper, we focus on the impact regularity of complex power on the small-signal synchronization stability of the MCPS. Firstly, we formulate the modeling of the MCPS and develop a systematical stability indicator to explicitly quantify the stability margin under various operating complex power. Then, based on the proposed stability indicator, the "resultant force" of complex power on the stability margin of the MCPS can be analytically characterized into a weighted summation form. Furthermore, we elaborate on the impact of each converter's active power and reactive power, respectively. Notably, we demonstrate the cancellation effect between the active power generation and consumption on the stability margin, which ultimately helps prevent SSI issues in the MCPS. The correctness of theoretical findings is well verified by simulations results.

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