Ensuring A Reliable Grid

The benefits of reliable electricity service are far reaching. Reliable electricity service contributes to your comfort, safety and security, and operations of businesses and services.

There are many factors that contribute to a reliable grid. Robust power system planning and forecasting allows IESO and partners to ensure future electricity needs will be met. Control room operators balance the grid second-by-second as power is generated and consumed. Rules, standards, emergency plans, control actions such as voltage reductions and public appeals are all tools that help to ensure a reliable grid for Ontario.

An interconnected system

Ontario's transmission system is part of a larger network of transmission systems across North America.

interconnection at niagara

This connection to a large, stable, continental power system enhances the reliability of electricity delivery in Ontario − exporting power when there's surplus supply and importing power when there's a shortfall.

Because electricity systems are interconnected − meaning instability on one system can have implications for all the others − it's important they share a common set of standards that govern the reliability of their operations and equipment. The IESO not only operates the electricity market and grid to ensure supply meets demand for electricity it is also the Reliability Coordinator for Ontario.

Reliability standards and market rules

North American Electric Reliability Corporation (NERC) Reliability Standards define the reliability requirements for planning and operating the North American bulk power system.

The IESO is a member of NERC, representing Ontario's interests in the development of standards affecting all jurisdictions across Canada and the U.S. The IESO is also a member of the Northeast Power Coordinating Council (NPCC), which is responsible for promoting and improving the reliability of the interconnected bulk power system in the northeast of North America.

The IESO's Market Rules define the roles and obligations of the IESO and all market participants who own or operate elements and facilities that form part of the IESO-controlled grid. Included in the obligations of market participants is the requirement to comply with applicable reliability standards. Failure to comply with the standards can result in sanctions.

The IESO administers the Ontario Reliability Compliance Program (ORCP) and works closely with market participants to ensure that they understand and follow their reliability obligations.

Cyber Security

computer server room Cyber security has rapidly developed into an essential component of power system reliability as broad sector digitization creates potential for new vulnerabilities.

In its role as Reliability Coordinator for Ontario, the IESO is responsible for enforcing a set of NERC “Critical Infrastructure Protection” (CIP) standards, which include cybersecurity standards. These standards require certain responsible entities to categorize their cyber systems based on the impact that their facilities, systems, and equipment which if unavailable, would affect the reliable operation of the power grid.

To mitigate cyber threats, the IESO has developed rigorous internal practices and also works closely with industry peers and government agencies to share information on cyber events and best practices.

Preparing for emergencies

While the IESO and others in the sector strive to maintain the reliable supply of electricity at all times, it's necessary to plan for and be prepared to respond to emergencies that compromise the stability of the electricity grid.

The IESO oversees the emergency preparedness and power restoration activities for Ontario's power system, including coordinating the restoration and emergency preparedness plans for those who participate in the electricity market.

The Ontario Electricity Emergency Plan, developed by the IESO in collaboration with industry stakeholders, sets out the overall framework for electricity emergency planning and response in Ontario.

In the event of a complete or partial blackout on Ontario's bulk power system, the IESO has in place the Ontario Power System Restoration Plan, which details the technical requirements to reliably restore power to the affected areas.

Read how the IESO directed the restoration of Ontario's power grid following the August 2003 Blackout.

Consumers can help: Public appeals

At times when the bulk electricity grid is strained, the IESO may issue a public appeal calling on consumers to cut back on their power consumption. Public appeals are infrequent. In the past, they have typically been issued during heat waves, extreme weather events and unexpected transmission or generation outages.

Learn more about what you can do when responding to public appeals.

Be among the first to learn about a public appeal

 Follow the IESO on social media: http://twitter.com/IESO_Tweets.

Consumers can help: Voltage Reductions

Voltage reduction is an emergency action available to the IESO to maintain reliability in situations when demand on the power grid exceeds the available supply. Voltage reductions can lower demand quickly, minimizing the likelihood of service interruptions. Voltage reductions have minimal or no noticeable impact on the general public as the voltages are still expected to be within established industry standards for electrical equipment used by residential, commercial and industrial consumers.

Regular Voltage Reduction Testing

Every 18 months, the IESO conducts province-wide system voltage reduction tests. These tests are not simulations but actual voltage reductions of three and five per cent. The purpose of voltage reduction tests is:

  • To determine how much power can be reduced through the two levels of reduction − three and five per cent
  • To identify equipment problems so they can be addressed
  • To help keep IESO and market participant staff familiar with procedures, and identify any deficiencies in the procedures that may need correction

The amount of relief provided to the grid is expressed as a percentage of Ontario demand. An example of voltage reduction results during the July 2019 test:

  • The three percent voltage reduction resulted in an average reduction of 1.30% in Ontario demand
  • The five percent voltage reduction resulted in an average reduction of 1.94% in Ontario demand    

Participation in voltage reduction tests is important. Broad participation also leads to a better quality of test, which helps support a robust and reliable power grid.

However, consumers may request a temporary exclusion from voltage reduction tests through their local distribution company if it addresses public health and safety concerns, potential damage to equipment, undue injury to the environment or possibly where loss of production might occur. Read more about a temporary exclusion.