Online Monitoring of Power Quality Indicators in Renewable Power Plants Using the Synchronized Phasor Measurement System of the Brazilian National Grid

System (BIPS), particularly wind and photovoltaic solar plants, requires improved Power

Quality (PQ) assessment, with emphasis on Total Harmonic Distortion (THD). In this context, the Brazilian National System Operator (ONS – Brazilian ISO), in cooperation with research institutions (UFSC and UTFPR), assessed an online PQ monitoring approach based on the existing Synchrophasor Measurement System (SMSF) infrastructure, using PMUs (Phasor

Measurement Units) implemented in multifunction Intelligent Electronic Devices (IEDs).

This work addresses the enhancement of the Operator’s Power Quality management framework through online and automated monitoring of total voltage and current harmonic distortion in wind and photovoltaic power plants. Based on multifunctional IEDs with PMU functionality in the Brazilian Power System, the study shows that, despite minor deviations relative to power quality analysers under IEC 61000-4-7 guidelines, PMU-based THD measurements provide a valid basis for real-time assessment. The proposed approach enables early detection of potential violations at the Point of Common Coupling (PCC), while reducing dependence on offline measurement campaigns, which remain complementary for targeted investigations and refined diagnostics.