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3.1 Introduction
The transmission system is the electricity “superhighway.”
The Role of Transmission
Electricity transmission is the process of transporting electricity from often remote areas where it is generated—usually over long distances—to the populated areas where local electricity distribution grids will deliver it to customers.
Electricity travels across the transmission grid at high voltages—above 100 kilovolts—for efficiency. Transmission lines typically consist of overhead power lines; however, some comparatively short distances are covered with underground transmission lines, usually within densely populated areas. Transmission can also occur through submarine power cables.
Reference Documents
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Transmission in Canada
The transmission system serves as a bridge between where bulk electricity is generated and where it is used. It moves electricity efficiently and safely across long distances and connects provincial, regional, and national grids. It is the generation system that converts mechanical energy to electricity and the distribution system that transports lower-voltage electricity.
The Transmission Grid
The electricity grid as a whole is the network through which electricity is generated, transmitted, and distributed. In this module, we will focus on the transmission system, which includes the control centre, transmission towers, and transmission lines.
Transmission Grid Management
Proper management of transmission is essential to ensuring the safe and efficient transport of electricity.
In each province and territory, transmission systems are monitored, controlled, and managed centrally from a control centre. Control centres can restore, divert, and interrupt power transmission remotely in response to equipment failures and other issues. They are also able to dispatch crews to investigate and restore unplanned outages.
Control centres also authorize planned outages to allow for inspection, maintenance, repair, and replacement of, or additions to transmission infrastructure. There is a close interconnection with control functions at the level of local distribution grids.
Control centres are an important feature of both transmission and distribution systems and function in a similar way in both contexts.
There are a growing number of interconnections between provincial transmission systems, and across the Canada-United States border. This enables trade in electricity and supply-demand balancing across wider geographic areas. Furthermore, the increasing number of interconnections improves reliability of supply and the efficiency of electricity use.
Transmission utilities must adhere to reliability standards established by the North American Electric Reliability Corporation or NERC. NERC’s mission is to ensure the overall reliability of the bulk electricity system in North America. Working with approximately 1,400 bulk electricity transmitters, NERC establishes and monitors shared reliability standards.
