PPL’s (NYSE:PPL) PPL Electric Utilities on May 24 filed with the Pennsylvania Public Utility Commission a petition for approval of tariff modifications and, to the extent required, associated waivers of certain commission regulations that are needed to implement the company’s Distributed Energy Resources Management Plan, which will govern the interconnection and operation of new distributed energy resources (DERs) deployed in the company’s service territory.
PPL Electric said that it seeks to proactively implement the 2018 revisions to the Institute of Electrical and Electronics Engineers (IEEE) Standard 1547, “Standard for Interconnection and Interoperability of Distributed Energy Resources with Associated Electric Power Systems Interfaces” (IEEE Standard 1547 or IEEE 1547-2018) and the related, forthcoming revisions to Underwriters Laboratories (UL) Standard 1741, “Inverters, Converters, and Controllers for use in Independent Power Systems,” (UL Standard 1741).
IEEE Standard 1547 outlines technical requirements concerning the interconnection and interoperability performance of DERs, including operation and testing, safety, maintenance, and security requirements. The company added that IEEE Standard 1547 was revised in April 2018 to transform how DERs interact with, and function on, the electrical distribution system by standardizing inverter capability requirements, incorporating improved communication interface standards, expanding grid support functions, and improving anti-islanding protections.
DERs interconnecting with the distribution system in the coming years are expected to be inverter-based, specifically equipped with “smart inverters” that comply with IEEE 1547-2018 and provide grid support functionality relating to voltage, frequency, communication, and controls. PPL Electric added that of specific importance to it and DER customers is the new requirement for DER inverters to be “smart” – that is, capable of providing grid support functionality and communications using revised specifications. IEEE 1547-2018 states that DERs must provide the local electric distribution utility with a standardized local interface for the monitoring and management of the DER, the company said.
UL Standard 1741 also applies to DERs and governs the physical testing procedures that manufacturers must perform to certify that a DER inverter meets IEEE 1547-2018, the company said, noting that UL Standard 1741 is under revision and expected to be released this year.
The company said that under its proposal, customers applying to interconnect new DERs with PPL Electric’s distribution system would be required to:
- Use company approved smart inverters that are compliant with IEEE 1547-2018 and forthcoming UL Standard 1741
- Install devices that enable PPL Electric to monitor and proactively manage DERs
PPL Electric said that its proposal would enable it to:
- Improve system efficiency, power quality, and reliability
- Operate more safely
- Increase the number of DERs that can be interconnected with the constrained portions of the company’s distribution system
- Reduce capital investments by the company where DER installations have traditionally required capital-intensive system enhancements or upgrades
The company noted that customer-owned DERs in Pennsylvania are governed by the Alternative Energy Portfolio Standards (AEPS) Act of 2004, which became effective in February 2005, and has since been revised by Act 35 of 2007 and Act 129 of 2008. The AEPS Act – which directed the commission to “develop the technical and net metering interconnection rules for customer-generators to operate renewable onsite generators in parallel with the electric utility grid” – enables customer-generators to interconnect their generating facilities with the distribution systems of electric distribution companies (EDCs), like PPL Electric.
The company added that since the commission’s AEPS Act regulations became effective in December 2006, the company has connected more than 8,000 customer-owned and third party owned DERs to its electric distribution system, and that of those, about 7,900 are solar photovoltaic (PV) facilities, with the remaining systems primarily consisting of combined heat and power, wind, and biomass.
On average, PPL Electric receives between 1,000 and 1,500 DER interconnection applications per year, with the majority of applications for solar PV systems, the company said, adding that it expects DER interconnection applications to rise as DER technologies become increasingly affordable and efficient.
PPL Electric said that after approval of its petition, all new customer-owned and third party-owned DER system installation must be equipped with smart inverters, DER management devices, as well as local communication interfaces and protocols that meet IEEE 1547-2018. No new DER system would be approved for interconnection unless both a company approved smart inverter and a DER management device are included in the DER system interconnection application, the company said.
Smart inverters provide additional functionality to standard inverters, which are devices that convert the direct current (DC) power produced by solar panels into the alternating current (AC) power transported on the electric distribution system for use in homes and businesses, PPL Electric said, adding that smart inverters are equipped with such grid support functions as:
- Fixed power factor, volt/VAR, volt/watt, and reactive power
- Low and high voltage and frequency ride through
- Power curtailment and remote on/off capability
That functionality allows the DERs that utilize smart inverters to operate in “sync” with the distribution system, thereby reducing power quality issues and maximizing potential DER output and operability, the company said. Smart inverters are also used in battery – energy storage – systems, electric vehicle chargers, and any other technologies that use DC power.
The company added that it currently envisions two types of DER management devices – which are the communication mediums between the DER inverters and the EDC – being used in conjunction with IEEE 1547-2018:
- Mesh network radios, which are the proposed default communication device to be used for customer-owned and third party owned DERs, and have the capability to connect wirelessly to the company’s new radio frequency (RF) mesh network
- Cellular modems, which would be used only in instances when a mesh network radio is not feasible, and are used by PPL Electric to communicate with equipment throughout its system, such as reclosers and capacitor banks
PPL Electric said that given its current inability to directly communicate and manage customer DERs to leverage grid support functionality, the amount of intermittent generation that can be interconnected must be limited to maintain system stability and reliability. The company said that it therefore requests the ability to monitor and manage DERs through the DER management devices by engaging their smart inverter grid support capabilities.
PPL Electric included in its petition its pro forma tariff supplement establishing the new PPL Electric “Rule 12 – Distributed Energy Resources Interconnection Service,” (DERIS), which provides customer application details and technical DER equipment standards under the DER Management Plan. Those tariff pages, the company added, provide details about the device requirements, including smart inverters, DER management devices, as well as DER monitoring and management.
PPL Electric said that it also requests, to the extent required, waivers of all or portions of commission regulations “52 Pa. Code §§ 75.13(c), 75.13(k), 75.22, 75.34, 75.35, 75.37, 75.38, 75.39, and 75.40,” because such waivers may be necessary to implement the company’s proposal. Section 75.13(k), for instance, states that “[t]he EDC and DSP may not require additional equipment or insurance or impose any other requirement unless the additional equipment, insurance or other requirement is specifically authorized under this chapter or by order of the commission.”
The company noted that it would require new customer-generators to install additional equipment – i.e., the DER management device – and impose additional requirements – e.g., that the customer-generator allow PPL Electric to monitor and manage the DER and that the DER utilize a standardized, non-proprietary communications protocol specified by the utility – that are not specifically authorized under Chapter 75 or a commission order. Therefore, the company added, it requests a waiver of Section 75.13(k), which is necessary to implement the DER Management Plan.