Hourly Generator Output & Capability

Hourly Generator Output & Capability Report
Mon	Tues	Wed	Thurs	Fri	Sat	Sun
						Apr 21
Apr 22	Apr 23	Apr 24	Apr 25	Apr 26	Apr 27	Apr 28
Apr 29	Apr 30	May 1	May 2	May 3	May 4	May 5
May 6	May 7	May 8	May 9	May 10	May 11	May 12
May 13	May 14	May 15	May 16	May 17	May 18	May 19
May 20	May 21

Note: Starting on March 17, 2009, the Capability of commissioning units will be shown as 0 (zero). During commissioning tests, if a unit is injecting energy into the IESO controlled grid, its output will be shown. At the same time, the capability of the unit will be shown as equal to its output.

Notice to Users: Starting on May 26, 2005, the DAWATSON station in the HYDRO section is displaying the aggregate generation output and capability from DUNFORD (HIGHFALLS), McPHAIL and SCOTTGLP generating stations, and GARTSHORE is displaying the aggregate generation output and capability from GARTSHORE, ANDREWS and HOGG generating stations.

Note: The AMARANTH station was formerly known as MELANCTHON and the PORT BURWELL station was formerly known as ERIE SHORES WIND FARM.

The Hourly Generator Energy Output & Capability Report presents the Energy output and Capability of each generating facility in the IESO-administered energy market with a maximum output capability of 20 MW or greater.

All energy values are shown net of station service. That is, the numbers published display the net energy contribution to the system to meet the demand for electricity in the market. If a unit is out of service and must draw energy from the system to support the maintenance work, then this electrical load will not be reported in this report.

Posted energy numbers are the product of operational metering, which by its nature, is less accurate and less reliable than revenue metering used for billing purposes. Because of the priority for early posting of energy outputs, the values have only been validated to a rudimentary degree prior to posting. For this reason, data upsets and other telemetering problems or technical issues can result in incorrect values of ±10MW. On occasions where data is missing, subsequent versions of the report will attempt to complete the missing hours.

Under the Market Rules, Chapter 4, section 7.3.4, the IESO is obligated to publish capability data for each generating unit or station.

"Capability" is defined as the unit's net maximum continuous rating (MCR) less the maximum derating within the hour. The unit's capability is a measure of the maximum amount of power that was capable of being produced by that unit during a given time.

Generating units that are out of service for maintenance will appear in this report as having zero capability in the respective hours. In addition, generating unit capabilities can frequently be reduced due to any of a number of specific equipment problems that may limit the output capability of the generator, but do not require the generator to shut down for repairs. Both of these are possible and expected conditions. In fact, different generating technologies have different outage requirements. Nuclear facilities generally have fewer outages, but their average duration can be longer than those needed for other generating technologies. Additionally, as units age and approach retirement, the frequency of forced outages and unit deratings may increase. Moreover, the time of the year can have an impact on outage schedules. Generally, more outages are scheduled during the spring and fall "shoulder seasons" in order to maximize availability of generating resources during the summer and winter months.

For those that would like to learn more about typical generator performance characteristics, please refer to the North American Electric Reliability Council's Generator Availability Data System (GADS). This service collects, records and retrieves operating information on the performance of electric generating equipment. GADS data are compiled annually and reported in the Generating Availability Report (GAR) and its accompanying summary statistical brochure.

Finally, while the generator capability indicates the maximum potential output from the generator in any hour, generating units often produce less energy than they are capable of at any given time. This is due to the IESO's dispatch, which must be constantly changing the amount of total generation on the system to meet the ever-changing demand for electricity. Also, the IESO's dispatch must also accommodate the requirement to carry a certain amount of operating reserve. Hence, the total capability of a generator in any particular hour will often exceed the total energy production of the unit for that hour.