3.3 Distributed Energy Resources (DER) Impacts on Distribution Systems

3.3.3 Benefits of DER Systems to Distribution Systems

Some of the benefits that DER systems, particularly in high penetrations, can provide to distribution systems include:

• Deferring construction:  DER systems that can offset loads, particularly peak loads, can be factored into whether and which distribution feeders need to be upgraded. For instance, reconductoring of some feeders or substation transformers may be deferred or completely avoided by using reliable DER sources to reduce loads.
• Increased reliability:  DER systems can improve reliability particularly if they are configured in microgrids or even “nanogrids” consisting of a single home or office building. After Japan’s devastating earthquake and tsunami in April 2011, the only operational hospital in the badly destroyed Sendai region was part of the Tohoku Fukushi University microgrid which never lost power.
• Minimizing power outages: DER systems with advanced functionality can “ride-through” short voltage and frequency sags and spikes, thus avoiding some power outages that might be caused by such anomalous events.
• Improved power quality: DER systems with advanced functionality can provide voltage support through autonomous volt-var control, thus maintaining voltage levels within the specified ranges.
• Improved efficiency: Advanced DER capabilities can improve efficiency through the power factor management and through maintaining conservation voltage reduction (CVR).
• Emission reduction: Renewable DER systems, by their nature, reduces emissions by offsetting fossil fuel generation
• Congestion management: DER systems can provide local generation to offset the transmission of power from remote bulk power generators. This can support transmission systems that are experiencing congestion.
• Frequency support: DER systems can provide frequency support to Independent System Operators (ISO) through either frequency smoothing (autonomous response to frequency deviations) or direct automatic generation control (AGC).
• Equipment Preservation: DER systems, in managing voltage deviations, can minimize the switching on and off of capacitor banks or the shifting of load tap changers.
• Bulk generation support: DER systems, by providing additional generation, can support the bulk generators by providing peak power, local power, and/or efficient power.
• Ancillary services: DER systems can provide, in aggregate, many of the ancillary services needed by the bulk power system, including operational reserve for different time frames, frequency support, reactive power support, peaking support, congestion support, etc.