Interconnection Issues



BEFORE THE

PENNSYLVANIA PUBLIC UTILITY COMMISSION

AND THE

DEPARTMENT OF ENVIRONMENTAL PROTECTION

Alternative Energy Portfolio Standards :

Working Group – PJM’S Modifications : Docket No. M-00051865

To IEEE-1547 Standards :

______________________________________________________________________

COMMENTS OF THE ENERGY ASSOCIATION OF PENNSYLVANIA

ON CLARIFICATIONS/ADDITIONS TO THE IEEE 1547 STANDARD

______________________________________________________________________

Introduction

These comments are filed on behalf of the Energy Association of Pennsylvania’s Electric Distribution Companies with special acknowledgement of the three Electric Distribution Companies, Allegheny Power, PPL Electric Utilities Corporation, and UGI Utilities, Inc. – Electric Division, and their request for a grounding exception in response to questions from the meeting of the Alternative Energy Portfolio Standards Net-Metering Interconnection Sub Working Group held on April 19, 2005. On April 20, 2005, the PUC Staff requested that comments be sent by e-mail to Carrie Beale.

I. The Three EDCs’ Concerns on Grounding Should Be Allowed

During development of the PJM Small Generator Interconnection Technical Requirements and Standards, the three EDCs asked to be included on an exception to the grounding requirement. The exception specifies a wye-grounded connection on the utility side of the distributed generators (DGs) step-up transformer for all new installations. EDCs’ concern with DGs that utilize DELTA high-side transformers revolves around the potential for an over-voltage condition that may result from a phase-to-ground fault on the utility side of the transformer. If a ground fault occurs on the primary side of the transformer and the utility breaker trips before the DG side opens, the DG may continue to back-feed the line and cause an over-voltage condition. Without proper relay protection to detect this type of fault, the voltage magnitude on the unfaulted phases can increase to 1.73 times the normal phase-to-ground voltage. Also, without a solidly-grounded Y transformer connection, a single phase-to-ground fault would produce little fault current, so this over-voltage condition on the other two phases could go undetected for an indeterminate period of time. This may result in equipment damage and pose a risk to other customers served by these lines. A wye-grounded connection on the utility side of the step-up transformer will not cause these same over-voltage conditions to occur. This configuration will also allow the use of more conventional ground relays to detect and clear phase-to-ground faults on the utility side of the transformer.

If the transformer connection used to connect the DG is grounded wye, this grounded wye having no ground resistor installed in the generator neutral, the DG will be able to sense ground faults on the EDC system and clear, thus preventing safety issues.

If the connection is DELTA on the EDC side of the transformer connection, the DG will not be able to sense ground faults on the EDC system. This will allow a fallen wire to remain energized. Further, where over-voltage relays are used to detect line-to-ground fault over-voltages, the EDCs identified two potential problems. These devices are usually set at a high value to prevent nuisance tripping, which may prevent the device from clearing a fault. Also, the clearing time is usually set to a value, which the EDC must consider. Both circumstances provide safety and liability issues that are matters of concern for EDCs. Transfer Trip would be an option on Transmission Systems/Sub Transmission Systems, but is impractical on a typical EDC distribution circuit, which has numerous system taps and single-phase protection devices.

EDCs desire to insure the most positive method for public safety and liability by insuring that a line trips for single line to ground fault. With this in mind, the installation of a grounded wye - grounded wye transformer, with no ground resistor in the generator neutral, and appropriate ground detection relays, has been adopted as the standard for some EDC systems, and should be accepted.

II. Interconnection to Secondary Networks

IEEE 1547 does not provide interconnection to a secondary grid network. The clarification in the PJM standard does provide for such interconnection. IEEE 1547 does provide for spot network connection on a limited basis, and EDCs agreed to do so.

III. The Other PJM Clarifications are necessary to create consistency between IEEE 1547 and existing PJM Tariff

. 

            The remaining clarifications presented by PJM at the Working Group meeting relate to requirements of the PJM Tariff which are either not addressed in IEEE 1547 or are addressed in a manner that is inconsistent with the PJM Tariff.  Certain of these apply only to generators wishing to sell into the PJM market and don't apply in other circumstances.  EAPA believes that these clarifications should be accepted. 

IV. Isolation Device Requirement

The National Electrical Code (NEC) requires the switch to be “Located where readily accessible” for all interconnected generation (Article 690.17). Additionally, the NEC always requires a disconnecting means at the source of power from utility to customer. The NEC is an applicable standard for the installation of interconnected generation in addition to the requirements of IEEE 1547. The utilities require a lockable, visible disconnect device that is accessible to utility personnel at all times. Without an external disconnect, utility personnel could require the DG system to be isolated from the utility electric system due to concern for for the safety of line workers, or other customers and concerns regarding damage to distribution equipment. The utility will need to disconnect the entire facility in order to disconnect the generation. A switch or circuit breaker located behind a locked door is not accessible and therefore not acceptable. An accessible disconnect device is necessary to maximize safety and minimize trouble for both the EDC and the DG.

Conclusion

The Energy Association and its members support the Commission’s and DEP’s efforts to identify issues relating to implementation of the Alternative Energy Portfolio Act. The Energy Association believes the exception on grounding offered by three companies should be preserved, as safety should be viewed as paramount. The other PJM clarifications apply only to generators wishing to sell into the PJM market and don't apply in other circumstances. EAPA believes that these clarifications on grounding, interconnection to secondary networks, other PJM clarification on tariffs and the isolation device requirement should be accepted. The overarching issue behind these exceptions is safety of utility workers, the generator, the utility system and the general public.

The Energy Association appreciates the opportunity to submit these additional comments, and stands ready to work toward greater safety together with the Commission and DEP. Respectfully submitted,

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J. Michael Love

Dated: April 29, 2005 President and CEO

Energy Association of Pennsylvania

800 North Third Street

Harrisburg, PA 17102

mlove@

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