STATCOM control strategies in energy-function-based methods for the globally optimal control of renewable sources during transientsAžbe, Valentin (Avtor) Mihalič, Rafael (Avtor) direct methodsgrid integrationpower-system dynamic stabilityrenewable sourcesSTATCOMThe inclusion of large numbers of renewable energy sources (RESs) can lead to the operation of electric-power systems close to their natural stability limits. To improve stability, the flexibility and fast control of RESs can be exploited. However, RESs must be “told” what to do for the sake of the “common good”. One possibility is to apply global control based on energy functions, but this requires the appropriate mathematical tools and models. In addition to the “real power feed”, the RESs’ power converters, among others, offer the functionality of a static synchronous compensator (STATCOM). Therefore, the aim of this paper was to develop energy functions for a STATCOM—the ones that consider its control strategies and limitations—that can be applied in energy-function-based methods for a transient-stability assessment and improvement. The two main contributions of this paper derive from the developed energy function (EF). The first contribution is the ability to use a direct method for the transient-stability assessment of an EPS that includes STATCOMs. The second contribution is the application of the developed EF in the control strategies of STATCOM and RES for a globally optimal, transient-stability improvement that can be used as a reference for other, simpler and more applicable control strategies. Such a reference has not existed until now. The STATCOM’s energy functions were developed as additional expressions that can be added to the already-known energy function of the electric-power system in the structure-preserving frame. The correctness of the developed energy functions was proved by applying them in a direct method for the transient-stability assessment and a comparison of these results with those obtained with a numerical simulation. Examples of the use of energy functions for the control of a STATCOM’s reactive current show how the STATCOM can improve the transient stability in a globally optimal way and can be used as a reference for a STATCOM’s simpler control strategies based on local parameters. An example of a RES’s reactive current control that is based on the developed energy functions shows that the RES can be successfully applied for a transient-stability enhancement. The paper can be seen as the first step towards a globally optimal control of the RES during transients.20222022-08-29 16:18:27Članek v reviji139064UDK: 621.31ISSN pri članku: 0142-0615DOI: 10.1016/j.ijepes.2022.108145COBISS_ID: 104460035sl