Ground Fault Overvoltage With Inverter-Interfaced Distributed Energy Resources

• Published in: IEEE transactions on power delivery Vol. 32; no. 2; pp. 890 - 899
• Main Authors: Ropp, Michael, Hoke, Anderson, Chakraborty, Sudipta, Schutz, Dustin, Mouw, Chris, Nelson, Austin, McCarty, Michael, Wang, Trudie, Sorenson, Adam
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.04.2017
• Subjects: Circuit faults; Distributed energy resources; distribution protection; effective grounding; ground fault overvoltage; Grounding; Impedance; Inverters; POWER TRANSMISSION AND DISTRIBUTION; Synchronous generators; transient overvoltage; Voltage control
• ISSN: 0885-8977; 1937-4208
• DOI: 10.1109/TPWRD.2016.2577884

Ground fault overvoltage can occur in situations in which a four-wire distribution circuit is energized by an ungrounded voltage source during a single-phase-to-ground fault. The phenomenon is well documented with ungrounded synchronous machines, but there is considerable discussion about whether inverters cause this phenomenon and, consequently, whether inverters require effective grounding. This paper examines the overvoltages that can be supported by inverters during single-phase-to ground faults via theory, simulation, and experiment. It identifies the relevant physical mechanisms, quantifies expected levels of overvoltage, and makes recommendations for optimal mitigation. It concludes that under many circumstances, effective grounding of inverters is not necessary to prevent ground fault overvoltage.