Epístolas y tratados

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The goal of our ETR strategy is to provide the best possible information to customers 6

throughout an outage restoration. This leaves us, as is the case for other utilities, with the 7

difficult task of trying to provide reasonable ETRs during storms before all damage has 8

been assessed. To deliver on this strategy, Nova Scotia Power focuses on trying to 9

communicate to the great majority of customers who will have power restored during the 10

first half of the event. For most customers, the power will be off because of damage to a 11

transmission line or distribution feeder; when that type of damage is fixed, power is 12

restored to a great number of customers at one time. Therefore, we target our early ETR 13

communication to outage events where greater than 100 customers have lost power. 14

15

During restoration efforts after Arthur, our practice of first communicating ETRs 16

applicable to outage events impacting 100 or more customers frustrated customers who 17

were among smaller pockets of outages, or even individual outages. In many cases, they 18

might have seen a restoration time applicable to their broader community, but it wasn’t 19

applicable to their street, or their end of their street, or their individual address. ETRs for 20

these smaller groups of customers are determined and communicated later in the outage 21

event. 22

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This ETR strategy has worked successfully in past storms, but with Arthur we had more 24

than 3,400 outage events impacting fewer than 100 customers on each event. This was 25

approximately 30,000 customers in total. This volume represents more than the total 26

number of outage “events” in any one of the storms detailed in Figure 16 earlier. 27

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In addition, ETRs were updated multiple times. Our initial ETRs were modeled based on 29

the weather forecast. When the actual weather turned out to be significantly worse than 30

the forecast, it meant that the resultant damage to the electricity system was worse than 1

our modeling predicted, and, thus, restorations would take longer. Secondly, because of 2

the large number of transmission outages, ETRs were based on when the transmission 3

lines were to be back on line. Once repaired, we were only then able to identify the 4

extent of damage on distribution lines and the resultant additional impact on ETRs. 5

6

10.5.1.1 Synopsis of ETRs

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On Saturday, July 5, the storm ETR strategy was implemented. While the storm was still 9

active, the ETR strategy was aligned to match the advance storm prediction model. As 10

stated earlier, this model was based on a number of variables including weather forecasts, 11

the geographical location of the storm’s impact, and past storm experiences. This early 12

ETR strategy determined that customers may experience a power outage until the end of 13

day on Sunday. By 6:00 PM Saturday, the actual outages had exceeded the forecasted 14

model and communication was updated to target having feeders back on by 11:30 PM 15

Sunday, and all customers restored by 11:30 PM Monday. 16

17

After the storm had ended, and damage assessment was in its early stages, the ETRs for 18

major feeders were updated to 11:30 PM Sunday. This information was based on the fact 19

there were 10 transmission outages that were targeted to be restored by Sunday evening. 20

These ETRs remained in place throughout Sunday as work on the transmission system 21

continued. As the transmission system came on-line, it became evident that there were 22

many distribution related events behind the transmission events and customers in those 23

areas would have extended outages. At 11:00 PM Sunday, July 6, with this new 24

information, ETRs on large outage events were updated to 11:30 PM Tuesday, with the 25

last customer back on by 11:30 PM Wednesday. This meant approximately 50,000 26

customers had their ETR updated. 27

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Throughout the day on Monday, more damage assessment information was being 29

collected and the number and severity of smaller outages was much greater than 30

forecasted. Monday at 9:00 PM, the estimated time for restoration of the outage events 1

with fewer than 100 customers was updated to 11:30 PM Friday. The ETRs on larger 2

outage events remained unchanged. 3

4

On Thursday, the ETR strategy then focused on the outage events with fewer than 100 5

customers. New ETRs were determined and communicated by individual community to 6

approximately 6,300 customers with an additional table that was added to the online 7

outage map information page and Customer Service Representatives. 8

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10.5.1.2 Learnings, Recommendations and Actions

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1. Nova Scotia Power’s ETR strategy was implemented after the November 2004 ice 12

storm, and has been successfully employed during numerous storms since then. 13

However, practices in ETR strategies have been evolving among North American 14

electric utilities that are exposed to severe weather. We recommend that Nova 15

Scotia Power work with the UARB’s consultant (who has experience in this area) 16

to further examine our ETR strategy, current best practices, and bring forward any 17

changes to the ETR strategy that would be in the best interest of customers 18

including any potential changes to the telephone systems. 19

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