June 14, 2021

Hydro Ottawa Limited Major Event: June 14, 2021

Prior To Major Event

1. Did the distributor have any prior warning that the Major Event would occur?

No, storms were forecasted however the severity of the lightning exceeded what was expected.

2. If the distributor did have prior warning, did the distributor arrange to have extra employees on duty or on standby prior to the Major Event beginning? If so, please give a brief description of arrangements.

Yes. Hydro Ottawa had a full complement of on-shift personnel, as well as a full on-call roster of field technicians and management personnel.

3. If the distributor did have prior warning, did the distributor issue any media announcements to the public warning of possible outages resulting from the pending Major Event?

No media announcements were issued by Hydro Ottawa.

4. Did the distributor train its staff on the response plans for a Major Event?

Yes

During the Major Event

1. Please identify the main contributing Cause of the Major Event as per the table in section 2.1.4.2.5 of the Electricity Reporting and Record Keeping Requirements. Please provide a brief description of the event (i.e. what happened?).

The main contributor of the major event was lightning. On June 14, Environment Canada issued a severe thunderstorm warning for parts of eastern Ontario, including the Ottawa region. Three lightning related outages were reported, including a Loss of Supply from the provincial transmission system resulting in a loss of load to an entire substation (1,749 customer hours). Another instance of lightning caused a feeder to trip (3,917 cust hours). Lastly, a lightning strike caused arcing within a switchgear at a Hydro Ottawa-owned substation, resulting in the loss of the entire station (29,409 cust hours). These three outages account for over 99% of the interruptions experienced by customers during the Major Event Day.

2. Was the IEEE Standard 1366 used to identify the scope of the Major Event? If not, why not?

Yes. Hydro Ottawa used the IEEE Standard 1366.

3. When did the Major Event begin (date and time)?

June 14, 2021 @ 4:25pm

4. Did the distributor issue any information about this Major Event, such as estimated times of restoration, to the public during the Major Event? If yes, please provide a brief description of the information. If no, please explain.

Yes, estimated time of restoration for the initial outages were issued by Hydro Ottawa’s Outage Management System, Power Outage Line and by email outage alerts beginning at 4:26pm on June 14th. Regular updates were provided throughout the evening.

5. How many customers were interrupted during the Major Event? What percentage of the distributor’s total customer base did the interrupted customers represent?

17,441 customers were interrupted during the Major Event, representing 5% of Hydro Ottawa's total customer base.

6. How many hours did it take to restore 90% of the customers who were interrupted?

The major outages from the lightning started June 14th at 4:25pm and 90% were restored by June 15th at 1:04am.

7. Were there any outages associated with Loss of Supply during the Major Event? If so, please report on the duration and frequency of Loss of Supply outages.

Yes, there was one Loss of Supply during the Major Event resulting from a lightning strike on the provincial transmission system. The outage affected 8,072 customers for a total of 1,749 customer hours. It contributed 0.023 to SAIFI and 0.005 to SAIDI.

8. In responding to the Major Event, did the distributor utilize assistance through a third party mutual assistance agreement with other utilities? If yes, please provide the name of the utilities who provided the assistance?

No

9. Did the distributor run out of any needed equipment or materials during the Major Event? If so, please describe the shortages.

No

After the Major Event

1. What steps, if any, are being taken to be prepared for or mitigate such Major Events in the future (i.e., staff training, process improvements, system upgrades)?

Asset Planning is taking a review of the 4kV Stations to ensure backup and offload capability is available. The System Office Grid Automation group is reviewing estimated time of restoration expectations and philosophy.

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