Differences in Stability Studies of Power Systems under the Presence of a High Penetration of Renewable Energy Sources in Portugal and China

Both Portugal and China are experiencing a significant increase of Renewable Energy Sources (RES) in their systems affecting the way the system is planned and operated. To cope with this challenges system operators need to develop methodologies in order to assess both the current and expected system behavior. In this paper, the methodologies and criteria that both system operators use in terms of steady-state, static security and transient stability analysis are compared. The major goal is evaluating the performance of the power system in future scenarios with the additional RES capacity. In order to illustrate and analyze the difference of the methodologies that both system operators of China and Portugal use, a set of RES extreme scenarios are developed using the test network CEPRI36 bus, that is properly adapted to the studies. Also the advantages of the new technical capabilities imposed by new EU regulations for RES (wind based or solar PV based) in what concerns voltage and frequency control are illustrated with the Portuguese power system.