The Impact of Integrating Renewable Energy Sources on Coherency Patterns in Electrical Power Systems

Coherency assessment is essential for wide-area protection and control of interconnected power systems. The transient response of renewable energy sources (RESs) differs from conventional generators. Therefore, the increasing penetration of RESs necessitates the analysis of hybrid power system dynamics to ensure system security and reliability during various disturbances. This paper proposes an online coherency assessment strategy based on the frequency signals acquired from phasor measurement units (PMUs) to include RESs in the analysis. Moreover, it investigates the impact of RESs on the generators' coherency patterns. Coherent groups are identified under both limited and wide-scale integration of RESs. Moreover, the system's dynamic response is investigated in the case of uniform distribution of RESs among voltage-controlled buses. The 10-machine New England power system is adopted in this study. All time-domain simulations are conducted on the DIgSILENT PowerFactory software. Results demonstrate the viability and effectiveness of the proposed strategy for online coherency identification in hybrid power systems. It also reveals that integrating RESs impacts coherent groups under certain conditions.