Frequency-domain screening methods and benchmarking for converter-based systems

This paper aims for providing an overview of existing frequency scan methods and recommending practical testing guidance via benchmarking studies. Section 2 firstly summarizes the general process of frequency scanning and the commonly adopted implementation options in available tools. The user-important scan parameters include the perturbation configuration and perturbation parameters, the selected scan output formats, such as single-input single-output (SISO) and multi-input multi-output (MIMO) impedance models.

Section 3 then follows by benchmarking various frequency scan tools implemented in two different electromagnetic transient simulation programs. The examples are selected on two PEID systems, by scanning their impedance representations at the AC and DC points of connection, considering both SISO and MIMO models. The benchmarking studies reveal that various tool implementations can derive consistent frequency scan results, which provides confidence in using frequency scan results for further screening analysis. In addition, sensitivity analysis of tool implementation approaches and scan parameters is conducted, providing practical experience for users to assure qualified scan results. Based on the benchmarking experience, Section 4 further provides recommendations. A robust workflow for a single-device standalone frequency scan test is proposed to derive the minimum impedance profiles for a

PEID’s frequency-domain screening, capturing the necessary coupling, control and operating point dependence. Furthermore, a few useful features for the frequency scan tools are suggested.

Section 5 finally concludes the paper with future applications of frequency screening methods and development needs from the transmission system operators (TSOs)’ perspective.