◊ Part of the ‘wind energy’ series of articles ◊
The Ontario ‘electricity grid’ connects thousands of generators to over 4 million load customers to provide safe, reliable energy delivery. The flow of power on the grid is constantly monitored and controlled by System Operators.
There are over 196,000 km of lines in service in Ontario operating at voltages from 4,000 to 500,000 volts. The electrical grid is made up of hundreds of nodes, parallel paths and branch circuits covering 75% of Ontario’s land mass. Power flows are determined by the electrical characteristics of thousands of elements in the interconnected network.
Routine switching operations, maintenance outages and disturbances continuously alter the load, energy availability and flows. System Operators use real-time monitoring and sophisticated computer applications to ensure that the system is within safe limits and can withstand various failure contingencies without catastrophic failure.
The grid connection points of generators is an important factor in power flow through the grid.
So how is that relevant?
The grid is an exceptionally complex electrical network. It’s energy flow cannot be represented by simple math on a spreadsheet. The IESO’s annual summaries of supply and demand are the rationalization of thousands of data points from a dynamic system that changes by the second. The data is the net result of the laws of physics, contracts, regulatory and operational factors. Any analysis based on those numbers will have limitations to its accuracy.
Injecting energy in southwestern Ontario may have little impact on the Ottawa region. Providing additional backup capacity for the South Kent Wind Farm by adding natural gas generation 500 km away in Napanee is hardly an optimal solution for the grid.
The grid is subject to market forces and operational considerations that result in generator dispatch constraints. These factors may impact the amount of wind generation on the system at any time.
The Bulk Electric System
Ontario’s Bulk Electric System (BES) has a specific definition according to established reliability criteria, however, generally it is considered the transmission system and all of the generators connected to it. Most wind generation capacity is connected to the transmission system. The IESO has jurisdiction over the BES as the reliability standards authority and administrator of the electricity market.
The Ontario transmission system has 10 electrical zones with interfaces that have specific transfer capability. In addition to the internal zones, Ontario has interties with Manitoba, Quebec, New York, Michigan and Minnesota. Transfer capabilities are important considerations when determining where generating stations will be located.
Additional information on BES power flow is available from the IESO.
The takeaway
Studies on wind energy that do not consider the engineering and operational aspects of the grid are inherently inaccurate.
Derek
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Next article… Providing backup energy sources
