(October 2010) AWEA’s manager of transmission policy refutes author Robert Blohm’s assertion that renewable power exacerbates America’s growing problems with frequency response.
Letters to the Editor
Transmission Rights Row
[Regarding “Transmission Rights Row ,” by Arnold Tesh and Deborah Haskell, March 2008]: While technological advances and the development of fiber optic communications was not foreseen by utilities companies when they executed easement agreements for transmission rights of way, the tremendous escalation of land values, especially near some metropolitan areas, may not have been foreseen by the easement grantors. With the land encumbered, the only way to gain benefit from what otherwise would be increased property value had the land not been encumbered, is to share in commercial benefit derived from the additional usage through fiber optics, which is not addressed in existing right of way agreements.
–Jan Gill, Load Research Analyst
(Company name withheld)
THE AUTHORS RESPOND: The proper methodology for determining potential damages does consider what individual rights the abutting owners retained in the encumbered easement property at the time of any alleged unauthorized use. However, individual abutting owners, whether part of a class or not, cannot claim a corridor value when they did not own rights to a corridor. Fiber requires corridor assemblage—something the individual abutters do not generally own. –AT and DH
Your May issue article “What Happened in ERCOT ” refers to the “voltage sag” that occurred in the system when the nearly 1,600 MW of wind and other generation stopped generating at around 6 p.m., just as the load started picking up. While there may have been system voltage issues during the event, it seems like the problem was really a frequency sag problem and not a voltage sag problem. Your Figure 1 shows the frequency sag, with the frequency dropping down to about 59.85 Hertz before the interruptible load was dropped. There is no plot of the system voltage during the event.
Imbalances in system load and generation usually show up in frequency. More load than generation and the frequency drops. More generation than load and the frequency rises. Most utilities have installed automatic underfrequency load shedding (UFLS) schemes to protect the overall integrity of the system by dropping blocks of load if the frequency falls below certain setpoints. Was the load shedding in the ERCOT event part of their UFLS scheme?
PG&E Transmission Planning Department
THE AUTHOR RESPONDS: I apologize for my error. At some point in writing this story I misread a chart and mistook hertz for volts. ERCOT confirms voltage was not affected by the February event, and says frequency never reached the 59.8 Hz threshold that would have tripped its automatic load shedding program (known in ERCOT as LAARs, “load acting as resources”). We’ve corrected this error on the archived article appearing on www.fortnightly.com, and regret any confusion it caused.– MTB
CORRECTION: In “The Late Great Gas Utility ” (April 2008), an error appeared on p.54. EIA’s natural gas consumption figures should have been 22.39 trillion cubic feet and 21.72 Tcf, not million cubic feet and MMcf. The error has been corrected in the archived article.
CLARIFICATION: A FERC Technical Conference on May 7