Finnish power system is continuing the shift to converter dominated system. Total wind power capacity of Finland is over 8.5 GW that is large number for a power system with minimum load of 7 GW. Wind generation is concentrated on the west coast of Finland, which makes stability of the area even more complicated. As the inverter-based resources (IBR) penetration level rises, converter driven stability issues are emerging. Finland has seen converter driven oscillations in both real-life and simulation.

Fingrid (Finnish TSO) has announced grid code changes that provide stability for IBR. For example, the latest grid code includes requirement for fast, inverter level voltage control, that is seen very beneficial for improving converter driven stability. Fingrid has for several years provided equivalent short circuit values (ESCR) for the Connectees for stability studies. However, methodology for conducting such studies under very low ESCR values, other than large scale EMT studies, has been missing. Conventional studies in single-machine infinite bus (SMIB) networks do not represent any kind of real-life situation and response is very different in SMIB-model and large-scale models.

Fingrid has developed an ESCR-benchmark model for PSCAD which is used to analyze converter driven stability in low ESCR environment. In the ESCR-benchmark model, the model of the studied power plant is cloned as multiple duplicates in different locations of the benchmark model to reach designed ESCR-value of the connection. In the simulations, the power plant shall ride through the grid fault and poorly damped converter driven oscillations shall not occur.

The study is done in two phases in the connection process. In phase 0, the power plant capabilities to operate in calculated ESCR level are analyzed with preliminary EMT-model of the plant. In some cases, the simulations do not include the plant level controls. Target of the study is to analyze the capability of the technology to operate as a part of the converter dominated network before signing purchase agreements. In phase 1, plant capabilities to operate in calculated ESCR level are analyzed with more detailed models that shall also include plant level controllers.

Fingrid sees ESCR benchmark model as an effective method to analyze the power plant performance in converter dominated network with minimizing the simulation burden caused by the simulations in large scale EMT-model. This paper presents the ESCR benchmark model and the revised simulation process for a connection process. The paper compares also the phenomena seen in the ESCR benchmark model to the large scale EMT model.