Simulating Distributed Energy Resource Responses to Transmission System-Level Faults Considering IEEE 1547 Performance Categories on Three Major WECC Transmission Paths | June 2020
The quantity of distributed energy resources (DERs) has increased substantially during the past two decades, and as a result, how these resources respond to power system disturbances has changed from minimally consequential to potentially critical. Transmission-level disturbances such as line and bus faults can negatively affect the voltage profile across vast regions of the Western Interconnection, with these voltages propagating downward to the distribution system and thus to DERs. With DERs having a current aggregate penetration level of approximately 9 GW on the Western Interconnection, unless appropriate power system planning is undertaken, power system faults—which in the past would have resulted in only the loss of a minor amount of DERs—might now, or soon, have a larger impact on system stability because of the potential widespread tripping of DERs. This study seeks to improve the modeling and understanding of DER response to regional voltage events, to properly identify DER requirements, and to prevent DERs from becoming a large contingency.
Most interconnections of DERs in the United States adhere to the Institute of Electrical and Electronics Engineers (IEEE) 1547 standard. An updated version of the standard, IEEE 1547-2018, was released in April 2018 in part to more precisely define a DER’s appropriate response during power system disturbances. IEEE 1547-2018 has defined performance categories that are effectively a menu of ride-through characteristics that can be applied to various DER technologies or for various overall DER penetration scenarios. This study departs from the traditional paradigm of in-depth frequency analysis of transmission-level contingencies and instead focuses on the overall system voltage response. Because the intention is to derive an anticipated DER response based on IEEE 1547 compliance, a focus on the system voltage is necessary because even slight deviations (dips less than 0.95 p.u.) can cause DER tripping and result in a significant generation loss.
The following bullets summarize the key findings of this research:
- Under heavy loading conditions representative of summer peak load in the Western Interconnection, the potential for widespread influence on voltage profiles following a transmission-level fault is significant. This highlights the potential for large losses of DERs depending on the implemented low-voltage ride-through criteria. Even with this large influence, however, the colocation of the fault with high DER penetrations is the primary factor when considering potential generation losses caused by faults.
- The IEEE 1547-2003 standard allows for a nearly immediate momentary reduction in the power output of DERs for relatively small voltage deviations from nominal, which can potentially result in a large loss of generation. For instance, the large penetrations of DERs in California lead to a nearly 4 GW loss of generation for specific faults in Southern California. Other interpretations or implementations of IEEE 1547-2003 could allow significant voltage ride-through capability, greatly reducing this potential generation loss.
- Performance categories I and II from IEEE 1547-2018 yield similar aggregate DER real power responses and similar overall system recovery characteristics. Implementation of the Category III ride-through criteria of IEEE 1547-2018 yields respectively smaller total real power output reductions.
Here is a link to the document: https://www.nrel.gov/docs/fy20osti/73071.pdf