Characteristics

The Ontario transmission system can be divided into nine zones.

Northwest Zone Characteristics
• The total resources generally exceed the zone peak demand.
• The generation is mainly hydroelectric with some coal.
• The zone is externally connected to the Manitoba and Minnesota systems.
• The 230 kV Manitoba interconnections are under phase shifter control. The Manitoba 115 kV interconnection is radial. The Minnesota 115 kV interconnection is under phase shifter control.
• To comply with NPCC and MAPP (Mid Continent Area Power Pool) system security criteria, the IMO is committed to implementing enhanced security criteria for the operation of this zone. These criteria will respect double-element contingencies during fair weather conditions. Currently, work is underway to develop mitigating measures for the implementation of these criteria. In order to ensure the reliability of the IMO-controlled grid in the Northwest, the enhanced security criteria will be implemented in stages when the mitigating measures are developed for the different recognized contingencies. It is expected that the enhanced security criteria will not be fully implemented until sometime in 2002 or 2003.

Northeast Zone Characteristics
• The total resources generally exceed the zone peak demand.
• The generation is mainly hydroelectric with some cogeneration.
• The zone is externally connected to the Quebec grid.
• The interconnection with Quebec is radial.

Essa Zone Characteristics
• The total resources are much less than the zone peak demand.
• The generation is totally hydroelectric.
• For analytical purposes, Des Joachims generation and 115 kV load, which is physically located in the East zone, has been modeled to be part of the Essa zone. The Essa zone is the primary point of receipt of Des Joachims generation.
• There are no external interconnections.

East Zone Characteristics
• The total resources exceed the zone peak demand.
• The generation is a mix of nuclear, hydroelectric, oil, and gas.
• The zone is externally connected to the Quebec grid.
• The existing interconnection with Quebec is radial. The new interconnection with Quebec will be High Voltage Direct Current (HVDC) transmission. This new interconnection is expected to go in-service in May 2003.
• The zone is also externally connected to the St. Lawrence interface with New York via phase shifter control

Toronto Zone Characteristics
• The total resources are much less than the zone peak demand.
• The generation is mostly nuclear and coal.
• There are no external interconnections.

Bruce Zone Characteristics
• The total resources are much greater than the zone peak demand.
• The generation is mostly nuclear.
• There are no external interconnections.

Southwest Zone Characteristics
• The total resources are well balanced with the zone peak demand.
• The generation is mostly coal.
• There are no external interconnections.

West Zone Characteristics
• The total resources are slightly less than the zone peak demand.
• The generation is mostly coal.
• The interconnection with Michigan is expected to be under phase shifter control by 2002.

Niagara Zone Characteristics
• The total resources are much higher than the zone peak demand.
• The generation is mostly hydroelectric.
• There is a free-flowing interconnection with New York.

Source: Ontario IMO