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Letters to the Editor

Fortnightly Magazine - October 2010

say the renewable energy agenda will make the “free rider” problem of not apportioning responsibility to the parties creating and offsetting rapid frequency change worse before we’ve solved it. Not only does wind penetration fail to increase our capability of managing variability that wind contributes to, but also it means displacement of fossil generation that could have provided that capability.

2) To provide rapid “governor response” reserve comparable to the 5 to 7 percent of capacity traditional fossil provides, wind, whose capacity (utilization) factor is a mere 5 to 30 percent, would need to back-down a reserve margin of 17 to 140 percent. Anything approaching 100 percent or more is, of course, impossible, while the rest of the range is easily uneconomic.

3) Yes, wind turbines can be programmed to provide inertial response (by the rotating blades), but only newer wind turbines have this capability, which only slows down frequency deterioration. Only governor response stops and begins reversal of the deterioration. This is illustrated by an alarming graph [in a presentation to NERC last year] showing the Eastern Interconnection’s inability immediately to begin reversal of, or even to stop completely, a sudden drop in frequency, contrary to the normal picture in Fig. 2 of my article. [ See Robert W. Cummings “ Overview Frequency Response Initiative ,” North American Electric Reliability Corp., (Princeton, NJ), July 28, 2009, p. 30. ]

4) Yes, change in wind is often in a somewhat slower but still rapid “regulation” range, but the megawatt changes are large and have huge requirements for regulation reserves. Those reserves are not redeployable, like governor response is, and are no substitute for governor response; to the contrary, they require proportionately more governor response on the system to back them up once those reserves are exhausted.– Robert Blohm

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