April 15, 2019

Hydro Ottawa Limited Major Event: April 15, 2019

Prior to Major Event


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

There were three basic causes for the outages on April 15th. There were outages attributed to Lightning that was forecast. The distribution transformer outages due to Flooding were anticipated due to heavy rain forecast and spring melt runoff. The Nepean TS outage was unexpected Loss of Supply. During a planned Hydro One maintenance outage on the Nepean T3, the companion T4 transformer tripped from relay protection due to an internal fault.

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.

Hydro Ottawa had a full complement of on-shift personnel, and a full on-call roster of field technicians and management personnel. All Operations groups were notified of potential flooding at the Weekly On-Call meeting.

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? If so, through what channels?

Hydro Ottawa had some prior warning that the water levels could be damaging and therefore did notify the public through social media and our website with tips and preparedness measures.

4. Did the distributor train its staff on the response plans for a Major Event? If so, please give a brief description of the training process.

Hydro Ottawa has an established Electrical Emergency Response Plan and Organization. Formal training is completed annually according to Market Rules, and a weekly preparation meeting is held to refresh on-call management personnel.

5. Did the distributor have third party mutual assistance agreements in place prior to the Major Event? If so, who were the third parties (i.e., other distributors, private contractors)?

Hydro Ottawa is a member of the Hydro One Mutual Assistance Agreement with Ontario Local Distribution Companies (LDC's) and a member of the North Atlantic Mutual Aid Group (US based). Hydro Ottawa also has standing service level agreements with forestry contractors, civil contractors and lines contractors for planned and unplanned work. No assistance was required.

During the Major Event


1. Please explain why this event was considered by the distributor to be a Major Event.

This event was considered to be a Major Event Day based on the IEEE Standard 1366 method. The daily SAIDI value of 6.14 on April 15, 2019 exceeded the daily SAIDI threshold of 5.3, as determined by IEEE Standard 1366, based on the daily SAIDI values for the past five years. The total number of customer hours interrupted was 34,425.

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

Yes, the IEEE Standard 1366 was used to identify the scope of the Major Event.

3. Please identify the Cause of Interruption for the Major Event as per the table in section       

The primary cause of interruption for the Major Event was Loss of Supply.

4. Were there any declarations by government authorities, regulators or the grid operator of an emergency state of operation in relation to the Major Event?        

No Emergency Response Organization activation was required. The Lightning outages were momentary / short duration. The Flooding outages were attended & monitored by on-shift and on-call personnel. Switching was undertaken immediately to restore load lost at Nepean TS from South March TS and Hawthorne TS feeders.

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

The first Lightning related outage began at 00:56. The first Flooding related outage began at 01:30. The Loss of Supply event began at 07:04.

6. What percentage of on-call distributor staff was available at the start of the Major Event and utilized during the Major Event?   

All on-call staff was available at the start of the Major Event, and 100% of on-call staff, were utilized during the Major Event.

7. Did the distributor issue any estimated times of restoration (ETR) to the public during the Major Event? If so, through what channels?          

ETR's were provided on the HOL website Outage Map, Power Outage Line and by email Outage Alerts. ETRs were published on social media, and through responding to requests from local radio stations seeking additional information.

8. If the distributor did issue ETRs, at what date and time did the distributor issue its first ETR to the public?   

ETR's for the initial outages were issued by our Outage Management System beginning at 01:39. Regular updates were provided throughout the day into the following day.

9. Did the distributor issue any updated ETRs to the public? If so, how many and at what dates and times were they issued?           

ETRs were revised as new information became available throughout the day.

10. Did the distributor inform customers about the options for contacting the distributor to receive more details about outage/restoration efforts? If so, please describe how this was achieved.         

Hydro Ottawa's social media posts advised to contact our Power Outage Line for additional information.

11. Did the distributor issue press releases, hold press conferences or send information to customers through social media notifications? If so, how many times did the distributor issue press releases, hold press conferences or send information to customers through social media notifications? What was the general content of this information?    


12. What percentage of customer calls were dealt with by the distributor’s IVR system (if available) versus a live representative?

84.2% of callers opted for the IVR and 15.8% of customers opted for a live agent.

13. Did the distributor provide information about the Major Event on its website? If so, how many times during the Major Event was the website updated?

The website homepage was updated to direct customers to safety information and tips related to safety during any potential flooding.

14. Was there any point in time when the website was inaccessible? If so, what percentage of the total outage time was the website inaccessible?

No, the website was accessible throughout the event with no interruption in service.

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

44,511 customers were interrupted during the Major Event, representing 13% of Hydro Ottawa's total customer base.

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

The Nepean TS outage was restored in 2 hours, 41 minutes.

17. Was any distributed generation used to supply load during the Major Event? 

Not directly, but all available distributed generation (DG) did remain paralleled to the Hydro Ottawa distribution system.

18. 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.    

1 outage from Loss of Supply from Nepean TS for a duration of 2.7 hours.

19. In responding to the Major Event, did the distributor utilize assistance through a third party mutual assistance agreement?     

No third party assistance was necessary.

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

No shortages were encountered.

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)?  

No debrief of the event was held with stakeholders. There will be continued focus on on-call and emergency response preparation.

2. What lessons did the distributor learn in responding to the Major Event that will be useful in responding to the next Major Event?

Further automation on some of the system backup option may reduce loss of supply duration in similar future events, and should be evaluated.

3. Did the distributor survey its customers after the Major Event to determine the customers' opinions of how effective the distributor was in responding to the Major Event? If so, please describe the results.      


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