This paper proposes a real-world oscillation event analysis framework for power systems that include inverter-based resources together with synchronous generators. Specifically, the proposed framework combines both measurement-and model-based techniques to readily identify potential oscillation sources, replay the oscillation event with numerical simulation, unveil the underlying oscillation mechanism, and suggest mitigation methods for a wide range of oscillation events. To strengthen the theoretical foundation of our analysis framework, this paper proposes atwin circuit theorythat provides theoretical support for one key utilized but not well-proven measurement-based oscillation source identification method—Dissipating Energy Flow. Ourtwin circuit theoryalso shows that adopting well-tuned grid-forming inverters can be a potential mitigation method for oscillation events. Finally, the effectiveness of our proposed oscillation event analysis framework is demonstrated by addressing a real-world 18-20 Hz oscillation event in Kaua‘i’s power system on November 21, 2021.

This paper introduces a versatile electromagnetic transient dynamic model for grid-forming inverter-based resources using the PSCAD software platform. The model offers a range of features, including the ability to choose from different types and combinations of DC sources, such as ideal DC source modules, photovoltaic (PV) modules, battery modules, and combined PV and battery modules. It also allows for the selection of either switching or averaged inverter models. The model encompasses various controller algorithms, including Pf/QV-based droop control, virtual synchronous machine-based control, and conventional outer-voltage-inner-current control in different domains, such as the dq domain, the αβ domain, and sequence-domain control in the dq domain. Additionally, it provides options for different current-limiting schemes, such as saturation-based and latching-based current limiters, along with anti-windup protection. Moreover, the model is adaptable to different MVA ratings and complies with the IEEE Std. 2800 requirement of negative-sequence current leading negative-sequence voltage 90◦–100◦for interfacing transmission systems. The model’s flexibility in power circuits, its multifunctional capabilities in operation and control, and its detailed modeling of controls and dynamics make it suitable for the study of various power system aspects requiring detailed modeling, such as investigating transient stability for interconnection studies, and impacts on protection systems for fault studies.

The increasing penetration of inverter-based resources (IBRs) introduces new challenges to power system simulations, particularly with the emergence of fast electromagnetic transient (EMT) dynamics and sub-synchronous oscillations (SSO) that require time-consuming EMT simulations. To reduce the time cost for simulating a large-scale power grid with IBRs, this paper proposes a novel participation factor-based approach for defining a critical zone for detailed EMT modeling and simulations, which includes the IBRs, synchronous generators, and the network components participating significantly in simulated contingencies. Both model-based and response-based methods are introduced for the estimation of participation factors (PFs). The case study on the 240-bus Western Electricity Coordinating Council (WECC) system demonstrates that the EMT zone determined by the proposed approach can effectively capture power system dynamics involving IBRs.

The escalating integration of inverter-based resources (IBRs) poses new challenges to power systems by introducing fast dynamics with higher frequencies, which may need to be simulated by an electromagnetic transient (EMT) program. As an alternative to conducting EMT simulations for the entire system, which is typically time consuming, hybrid simulation between EMT and phasor-domain transient stability (TS) can greatly reduce the computational burden while preserving the detailed fast dynamics in the EMT zone. This paper establishes an EMT-TS hybrid simulation platform using open-source tools, specifically ParaEMT, GridPACK, and HELICS, which are the EMT simulator, TS simulator, and interface framework, respectively. Case studies on the 240-bus Western Electricity Coordinating Council (WECC) system demonstrate that the developed ParaEMT-HELICS-GridPACK hybrid simulator can accurately capture both slow electromechanical and fast IBR-driven dynamics with a 2.4× speedup.