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With the growth of renewable energy, the number of distributed energy resources (DER) feeding into the electric power system (EPS) is growing too. Since a traditional EPS is not designed to accommodate power coming from distributed sources, utilities are facing a number of challenges.

Recently Leidos hosted an interactive webinar to examine these challenges — and to discuss the value of performing site-specific interconnection impact studies to help ensure a successful integration of DER into an EPS.

DER Interconnection Challenges

Some of the key challenges we identify in the webinar are:

  • Reverse power flow and voltage rise. Energy flowing from the DER towards the substation is in reverse of the traditional power flow from the substation to the distribution load. Significant reverse power flow can cause equipment thermal overload and unacceptable voltage rise.
  • Voltage regulation and flicker. Rapid changes in voltage, which are common with energy coming from intermittent renewables, can cause unacceptable voltage flicker.
  • Short circuit and protection. DER interconnections inject fault current into the system, which can desensitize relays, cause nuisance tripping and exceed equipment ratings.
  • Unintentional islanding. DER could continue to supply load even when an EPS is offline due to a fault or other event.

Conducting an Interconnection Impact Study

Typically, utility companies integrating DER into their EPS fall into one of three categories:

  1. No existing DER and interconnection criteria.
  2. Some DER and interconnection criteria but looking to learn more about what others in the industry are doing.
  3. High level of penetration of standards and criteria to help protect the system, perform cost-effective mitigation and streamline the interconnection process.

Solutions vary widely between utilities with vastly different amounts and types of DER connecting onto their systems. However, we discuss the key challenges in depth and provide case studies on each to highlight how utilities have addressed issues in real-life scenarios.

Our webinar provides a detailed look at the information that a utility should gather to create an interconnection impact study for whichever category it currently falls. We describe how to use the results of the study to create models and cost-effective plans. Finally, we outline how to align the models and plans with applicable interconnection standards and industry practices for an effective interconnection screening that meets regulatory requirements.

The webinar offers a basis to develop a set of best practices to guide DER interconnection studies. View the webinar now to find out how to best prepare for a smooth DER integration.

Distributed Energy Resources  Webinar.pngWEBINAR

Distributed Energy Resources: Interconnection Impact Studies Support Successful DER Integration




John Cerulli is a registered professional engineer with 27 years of experience in electric utility distribution engineering and planning. John performs DER interconnection impact studies and distribution planning services for utilities across the United States.