Date of Award


Document Type



Santa Clara : Santa Clara University, 2023.

Degree Name

Master of Science (MS)


Electrical and Computer Engineering


Most renewable energy generation connected to the distribution level of the electric grid is connected through an inverter. To prevent an unintentional islanding condition, these inverters employ a variety of anti-islanding protection schemes. The Sandia Frequency Shift (SFS) method of anti-islanding protection is considered to be the most effective scheme built into grid-connected inverters. Much of what makes it so effective is the postive feedback loop that it creates when the inverter’s connection to the bulk power system is lost. However, this same positive feedback can have negative impacts on the stability of the inverter even when it is connected to the bulk power system. Depending on the SFS formulation used, this impact may be major or minor. The effect of SFS on the stability of the inverter are two-fold: (1) creating small-signal instability that manifests even when the inverter is not generating power, and (2) creating transient voltage instability at certain levels of power export to the bulk power system. These impacts should be considered when designing a grid-connected inverter.

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