By Babak Enayati
This article highlights the necessity to have standards like IEEE 1547. Due to the high penetration of distributed energy resources (DERs) in the electric power system (EPS), the utility companies are facing challenges to interconnect the DERs onto their EPSs. These challenges include power quality, protection, etc. Since most DERs are capable of providing grid support functionalities to resolve some of these challenges, the IEEE 1547 standard is under a full revision to allow DERs and the utilities to utilize these functionalities. This article also describes some of the major draft proposed changes to the current version of the standard.
The current electric power system (EPS) is not well positioned to handle high penetration of distributed energy resources (DERs) on the distribution system as that system was mainly designed to deliver power from the transmission system to load. Hence, increasing amount of DER interconnections into the distribution system created various technical challenges: protection, power quality, response to bulk power system disturbances, and voltage and frequency regulation.
Many countries have programs for ubiquitous deployment of renewable energy resources to potentially enhance grid resiliency, defer utility investments and provide environmental benefits. Since the concept of distribution system connected DER is still new to the power industry, utility distribution system engineers do not have a full understanding of how various types of DERs perform under normal and abnormal system conditions. This presents a challenge for the engineers to resolve the technical issues associated with high penetration of DERs.
Standards play a key role in creating a harmonious way of handling the DER interconnection issues. Lack of standards will certainly create inconsistency for the organizations that deal with the DER interconnections, including utilities, developers, DER manufacturers and nationally recognized testing labs (NRTLs). This inconsistency can cause costly interconnections, challenges with the DER testing and certification.
IEEE 1547, Standard for Interconnecting Distributed Resources with Electric Power Systems, is one of the standards that is widely accepted in the power industry. It provides a set of requirements that each DER shall meet at the point of common coupling (PCC) or the point of interconnection (POI). When the standard was developed, the penetration of DER on the EPS was low. Hence, the 2003 version of the standard did not allow any grid support functionalities by the DERs, including voltage regulation, frequency regulation, and ride through.
As the DER penetration level increased during the past few years, the EPS faced issues like protection, power quality and potential bulk system instability. DER manufacturers claimed that the generators are capable of resolving most of the issues that they cause on the EPS but the lack of standards was a barrier towards implementing these solutions. Most utilities required IEEE 1547 standard compliance for distribution system DER interconnections and the standard did not allow any grid support functionalities. As the need to allow the DER grid support functionalities arose, the IEEE 1547 working group submitted a project authorization request (PAR) to the review committee to start the full revision of the standard.
Upon the PAR approval, the working group members started the revision process. Some of the major sections of the standard that are currently being revised are:
- Voltage regulation. The draft version of the voltage regulation section mandates the capability of each DER to regulate the voltage at either the PCC or the POI. It is proposed that even though this capability is mandated, enabling this capability will be at the Area EPS Operator’s discretion.
- Response to abnormal system conditions. North American Electric Reliability Corporation (NERC) and Independent System Operators (ISOs) are concerned about the adverse impact of high penetration of DERs onto the EPS’s bulk power system stability. The concern is during bulk power system disturbances the EPS may need support from the DERs to recover from the abnormal condition. The draft proposed section allows DERs to ride through bulk power system disturbances. Ride through capability and performance is mandated in the proposed draft.
- Power quality. The draft version of the power quality section provides a set of requirements for EPS harmonics, flicker, and temporary and transient over voltage. These requirements are measured at the EPS electric circuit and shall not be violated due to the DER interconnection.
- Island systems. The technical requirements that each DER shall meet in order to operate in an island with a portion of the EPS will be addressed in this section.
- Interoperability. As the DER provides the grid support functionalities, it is crucial for the utilities to be able to monitor and control these functionalities. The proposed interoperability draft section of the standard provides a minimum set of requirements from communication and data monitoring perspectives that each DER shall meet.
While the standard is currently being revised, an amendment was approved in 2014 to allow voltage/frequency regulation and ride through upon mutual agreement between the area EPS and the DER operators. The IEEE 1547 working group members have recognized the need to have the revised standard published as soon as possible. The team is working hard to meet the industry needs.
*Note: All information provided from items 1 to 5 is subject to change as the standard had not gone through the ballot by the IEEE Standards Association (IEEE SA).
Babak Enayati, an IEEE Senior Member, received his PhD in electrical engineering from Clarkson University, Potsdam, NY in 2009. He is currently a lead research development and demonstration engineer at National Grid, Waltham, MA and Chair of the Massachusetts Technical Standards Review Group (MA TSRG). Over the past ten years, Babak has also worked on distributed generation interconnection, power system protection, control of microgrids, modeling, and aging analysis of electrical asynchronous machines, optimization of electrical drives, multi-generation power system dynamics analysis, and control of switched reluctance motors. He joined IEEE in 2006 and currently is the IEEE Power & Engineering Society Boston chapter chair. Babak is the Vice Chair of the IEEE 1547, Standard for Interconnecting Distributed Resources with Electric Power Systems.