This paper presents a Python-driven graphical user interface (GUI) explicitly crafted for benchmarking the electromagnetic transient (EMT) models of inverter-based resources (IBRs) across Matlab/Simulink and PSCAD/EMTDC platforms through impedance measurement techniques. The GUI ensures a user-friendly experience, enabling seamless interactions between these platforms while offering advanced visualization of impedance measurement results and associated benchmarking errors. This paper delves into the Python-based implementation that powers these features. Through a series of case studies, the tool's efficacy in benchmarking IBR's EMT models is validated. The benchmarking methodology and corresponding GUI design are extensible to other leading EMT platforms such as DIgSILENT/PowerFactory, PSSE, EMTP-RV, EMTP-ATP, and DSATools TM /SSAT, fostering expansive and holistic research in the stability analysis of the IBR-based modern power systems.

This letter, based on measuring the admittance of a black-boxed grid-following inverter (GFLI) at seven distinct operating points to synthesize an operating-point-parameterized state-space model (OPP SSM), presents an efficient method for analytical prediction of the maximum transferable active power (MTAP) injected by the black-boxed GFLI into the grid under any arbitrary grid condition and reactive power injection level. The proposed method obviates the need for repetitive electromagnetic transient time-domain simulations or frequency-domain impedance criteria by gradually increasing active power output until the MTAP is reached. The feasibility of the synthesized OPP SSM for MTAP prediction has been experimentally validated on a power-controlled GFLI, demonstrating its potential for aiding the integration of inverter-based resources in modern power systems.

A document by Weihua Zhou . Click on the document to view its contents.

The theoretical maximum power transfer capability of the phase-locked loop (PLL)-based grid-following inverters can be limited under weak-grid conditions due to the non passivity of control loops. This article aims to reveal the passivity violation mechanism and develop passivity oriented feed-forward control to cancel out the negative effects of inner current control and PLL on low-frequency passivity. To this end, the contributions of these control loops and the mutual interactions among individual control loops to inverter terminal admittance are identified using the admittance decomposition technique, based on which the nonpassivity effect of each control loop is canceled out using a point of common coupling voltage feed-forward loop. The effectiveness of the presented control loops passivation method is validated by eigenvalue analysis, simulation studies, and experiments.

As power systems undergo a transformation with increasing inverter-based resources (IBRs), understanding the stability and dynamics of IBR-dominated systems becomes imperative. Though analytical models offer insights into these changes, intellectual property constraints introduce a challenge due to the black-box nature of IBRs, highlighting the importance of frequency-domain-based methods using IBRs’ measured admittance. While simulation environments provide ease in impedance measurement, real-world implementation faces challenges due to the absence of ideal voltage or current sources. This has prompted the use of varied devices, such as power amplifiers and frequency response analyzers, for perturbation generation and injection. Notably, utilizing another measurement inverter as the perturbation source offers a promising approach, despite its limitations such as degrading system stability and prolonging the measurement time. This article introduces an innovative control strategy for the measurement inverter, detailing the effects of abc/dq and dq/abc transformations on the measured admittance. The groundbreaking contributions are the revelations about the admittance contributions of these transformations and the introduction of double phase-locked loops, optimizing both system stability and measurement time.

The conventional virtual synchronous generator (VSG) is normally designed to meet certain operational and control requirements in the islanded mode. However, once the VSG is switched to grid-connected mode (GCM), the robust operation cannot be guaranteed under different grid conditions. It can lead to, especially in strong grids, poor dynamic performance such as significant oscillation, long settling time, and high overshoot. In order to improve the VSG performance in the GCM, this article first analyzes in depth the inherent coupling between the active and reactive power and its dependence on the grid conditions, such as the short circuit ratio, grid impedance ratio Xg=Rg, and the wide grid impedance variations. Afterwards, an online grid impedance estimation-based adaptive VSG (AVSG) control strategy is proposed to ensure the robust operation of the VSG considering both strong and weak grid conditions. This technique allows the operator to specify the desired settling time of output power and damping ratio.To estimate the grid impedance in real time without extra hardware and reduce the associated impacts on power quality, an online event-based grid impedance estimation algorithm is embedded into the control loop of the AVSG. Both the simulation and experimental results indicate that, compared to the conventional fixed-parameters-based controller design method, the AVSG enables the desired performance such as no oscillation, specified time duration for the settling time, and minimal overshoot regardless of the grid conditions.