The Impedance-based stability assessment (IBSA) methods are widely used to identify control interaction issues between inverter-based resources (IBRs) and transmission grid. The IBR impedance models can be obtained and analyzed in different reference frames and forms, such as positive sequence single-input single output (SISO) and dq-frame multi-input multi-output (MIMO) forms. Accordingly, different IBSA methods should be applied. In this paper, six IBSA methods are reviewed, compared, and their applications are demonstrated. Merits and shortcomings of each method are discussed, and recommendations are presented for engineers and researchers. The IBSA results are compared with electromagnetic transient (EMT) simulations in two test systems involving doubly-fed induction generator (DFIG) and full-size converter (FSC)-based wind parks (WPs).

Accurate initialization of large-scale power systems involving inverter-based resources can significantly reduce the computation time needed for reaching steady-state conditions in electromagnetic transient simulations. This paper presents a novel method for initializing detailed Photovoltaic Park models for electromagnetic transient simulations. The proposed approach uses the load-flow simulation results of the system to initialize electrical components and control variables of the PV park. The validity of the proposed initialization is demonstrated through the EMT simulations of aggregated and detailed representations of the PV park and its integration into a large-scale power system via three case studies. The results indicate that the existing initialization method significantly reduces the computational time required to reach steady-state, compared to the existing technique.

Impedance-based stability assessment (IBSA) is an effective method to study sub-synchronous control interaction (SSCI) with inverter-based resources (IBRs) in modern power systems. An IBR's required frequency-dependent impedance model can be obtained via the positive sequence scanning method. In this paper, single-sinusoidal signal and multi-sinusoidal signal-based methods for frequency scanning are investigated and evaluated. To benefit from the advantages of both schemes, hybrid scanning is proposed including perturbation signal, amplitude, and frequency segmentation settings. Additionally, a modified quadratic phase shift scheme is proposed for reducing the high magnitudes of multi-sinusoidal signals. All methods are validated and compared using the average value model of a doubly fed induction generator. The guidelines and recommendations are provided for the proper usage of the proposed hybrid scanning in the sub-synchronous frequency range.

In this paper, power-over-fiber technology is used for combined power and data transfer applying amplitude-modulated light representing a pulse-width modulated signal that could be used for control of, for instance, power semiconductor devices in high-power converters. Even though the concept is generally applicable, an experimental verification aiming for a gate-driver of a switch in a modular multilevel converter is presented. In order to achieve a good resilience against electromagnetic noise, a concept where the modulated light is demodulated as a comparably powerful current signal is employed. A 5 MHz boost converter steps up the voltage to 15-20 V, such that silicon or silicon-carbide based power devices could be controlled. From the results, it can be concluded that it is possible to achieve transmission of a control signal with a latency of less than 500 ns for a gate drive unit of a high-power converter. The concept can easily be scaled up to powers of several watt.