Electric utilities are faced with the challenge of managing a range of aging distribution assets that are critical to system reliability. They also are threatened with potentially huge costs as...
T&D Reliability: The Next Battleground in Re-Regulation
prioritize their maintenance, on the theory that getting rid of the worst problems first is a good way to manage the total. The PUCs have jumped on this bandwagon en masse of late, probably because it appeals to their sense of protecting the individual customer.
The typical worst-circuit reporting requires that the utility provide the equivalent of SAIDI, SAIFI and CAIDI on a circuit-by-circuit basis, or at least for the worst five percent or so of circuits. Sometimes two lists are required, one ranked by frequency and one by duration. Typically, companies will be allowed to exclude circuits with less than five customers. Generally these programs address distribution circuits only.
One problem with worst-circuit reporting is that it aims at the wrong target. The definition of a distribution circuit can be a matter of convenience, and can even change seasonally for some utilities that use switching to maximize the use of their distribution plants (something we may begin to see more of as a cost-cutting measure). Moreover, by sheer accident of customer location and load growth, some rural feeders (circuits) may be more than 50 miles long, while their urban counterparts are less than 10 miles long. What is needed is an ability to focus on groups of say, 50 to 100 customers.
Many utilities that used circuit data to prioritize their maintenance now use their newly automated mapping systems to provide data at the device level, allowing even better targeting of trouble spots, since devices (fuses) often exist for groups of 50 to 100 customers. PUCs would do well to heed this change, because a 50-mile feeder still can mask some serious problems for small groups of customers. In fact, some PUCs do require reporting of the customers who have been interrupted more than say, 10 times per year (em data that depend upon the ability to record interruptions by device, not just by circuit. (Remember, even customers that do not call in are counted as interrupted if their service was cut, so customer call data alone are not sufficient to compute a 'worst-customers' list.)
Some PUCs require reporting only of worst circuits, whereas some set standards and impose incentives. Some emphasize that worst circuits should not repeat from one year to the next. Many that require reporting also require disclosure of remediation programs.
4. Reliability programs. The new emphasis on worst-circuit reporting opens the door to a greater degree of regulatory scrutiny and control. After asking utilities to report their worst circuits, it is natural to ask what efforts are being made to remediate those problems. The answer may invite a look at root causes (em and then the specific project activity and spending designed to remediate the problem.fn2
Once on that path, though, it is a short step to ask for detail on all reliability programs. This request typically will include: vegetation management; wood pole inspection, treatment and replacement; line rehabilitation; lightning mitigation; animal mitigation; underground cable maintenance; capacity reinforcement; substation maintenance; and sectionalizing. In large companies, these expenditures can total more than $100 million per year. Most of