Advanced Flexible Solar Interconnection into Distribution Systems With Dynamic Asset Rating and Fail-Safe Mode Control

Avangrid piloted the first Flexible Interconnection (Flex IX) project in North America with two sites running for 4 years. Lessons learned from these pilot projects showed that solar farms can experience measurable curtailment due to overloading of grid assets based on their static thermal limits in normal grid operation and the fail-safe (FS) mode control of solar generation output during loss of communication (LOC) contingencies. To address these issues, the paper proposed two advanced Flex IX technologies, i.e., (1) dynamic asset rating (DAR) and (2) enhanced FS mode control by dynamically configuring DER controllers. DAR is to holistically update thermal ratings of grid assets, i.e., substation transformers (Xfmrs) and feeder conductors, in Flex IX by leveraging real-time meteorological measurements. Advanced short-term load forecasting based on Multivariate Linear Regression, TSMixer and Reservoir Computing has been proposed to update the curtailment configurations of Flex IX controllers when communication outages occur. These developed technologies have been validated with the data from the Flex IX sites from Avangrid. Results show that DAR reduces solar curtailment by 23.89% in the synthetic case and by 100% in the Flex IX demonstration site. And the improved FS mode reduces communication outage related solar curtailment by 76.48% in the synthetic case and by 100% for the Flex IX demonstration site.