In this article:
Overview
The Generating Availability Data System (or GADS) is a database of statistical reports from power stations in the United States and Canada.
Recognized as a valuable source of reliability information for total unit and major equipment groups, GADS is widely used by industry analysts in a variety of applications.1
GADS is maintained by the North American Electric Reliability Corporation (NERC) which requires eligible power producers to submit reports2 for:
Monthly Performance data on a quarterly basis.
Event data on a quarterly basis.
GADS is mandatory for the following renewable energy plants in the USA and Canada:
Wind sites with a Plant Total Installed Capacity greater than 75 MW that have been commissioned on January 1, 2005 or later.
PV sites with a Total Installed Wind Capacity of:
100 MW or more in 2024
20 MW or more in 2025.
2See Drive Reports: NERC Events & GADS Performance for more information.
In Drive, most NERC Performance metrics are calculated as the sum of hours in which an Asset has been in a specific state during a given period.
These states are defined by the Events recorded in Drive and the NERC Performance markers assigned to these events.
Default NERC Performance categorization per Event Code ensures that relevant events can be automatically categorized. The defaults include:
The markers assigned to PF Events 3 (any Event with a PF prefix, e.g., PF100) is predefined for ALL Customers (see below)
The markers assigned to Fault Code Events 4 are either
based on Power Factors' recommendations for major turbine and inverter manufacturers
defined by the Customer during Event Configuration.
3NERC Performance markers for PF Events cannot be changed.
4This option primarily applies to Wind Fault Codes as Power Factors strongly recommends configuring Inverter Fault Codes as Warnings – which do not have any categories associated. See the Drive Events: Warnings (User Guide) for more information.
To see how an Event Code is categorized, go to the Knowledge Base dashboard in the Manage module and view the NERC Performance column:
If the default marker does not accurately convey how an Event affects a Site’s performance, a different marker can be applied.
However, customers should read the following NERC resources before making any updates:
See Drive Events: NERC Performance Categorization for detailed instructions on how to categorize Events.
The tables below list all the available markers for PV and Wind sites, including which PF Events are assigned these markers by default.
NERC Performance Markers | PF Events | |
|---|---|---|
1 | Forced Outage Inverter Hours |
|
2 | Inactive Reserve Inverter Hours | N/A |
3 | Maintenance Inverter Hours | N/A |
4 | Mothballed Inverter Hours | N/A |
5 | Planned Inverter Hours | N/A |
6 | Reserve Shutdown Inverter Hours |
|
7 | Resource Unavailable Inverter Hours |
|
8 | Retired Inverter Hours | N/A |
9 | Service Inverter Hours |
|
NERC Performance Markers | PF Events | |
|---|---|---|
1 | Contact |
|
2 | Forced Turbine Hours |
|
3 | Inactive Reserve | -- |
4 | Maintenance Turbine Hours | -- |
5 | Mothballed | -- |
6 | OMC Forced Turbine Hours5 | -- |
7 | OMC Maintenance Turbine Hours5 | -- |
8 | OMC Pandemic (9015)5 | -- |
9 | OMC Planned Turbine Hours5 | -- |
10 | Planned Turbine Hours | -- |
11 | Reserve Shutdown |
|
12 | Resource Unavailable |
|
13 | Retired | -- |
5These NERC Performance markers (“Outside Management Control”) are only relevant for reporting prior to 2024. NERC does not require reporting for these categories from January 1, 2024, so these markers should not be used.
See Drive Events: NERC Performance Categorization for detailed instructions on how to categorize Events.
In order to summarize the hours spent in each NERC state, Drive determines the relevant event for each timestamp. This determination is based on the NERC Performance markers of any events, and the NERC definitions:
Appendix H: Inverter Group States and Hours
Appendix I: Outage Classification Guidelines
GADS Wind Turbine Generation (2023)
Appendix D: Terms and Definitions
Turbine States and Hours
Appendix H: Outage Classification Guidelines
Appendix I: Overlapping Events
GADS Wind Turbine Generation (2024)
Appendix G: Turbine States
Appendix H: Outage Classification Guidelines
Appendix I: Overlapping Events
The primary result of the GADS Performance calculations is the quarterly NERC GADS Perforamnce reports. See Drive Reports: NERC Events & GADS Performance for more information.
In addition to the reports, the NERC state of any inverters or wind turbines can be visualized via the:
For Wind sites, customers can use the NERC_STATE.CALCULATED attribute to display the data for a specific reporting month for All Turbines in a Subgroup:
Meanwhile for PV sites, customers can use the NERC_STATE.CALCULATED attribute to display the data for a specific reporting month for All Inverter Groups:
NERC_STATE.CALCULATED is visualized at the generator’s data resolution. This data can then be exported as an Excel file for further analysis.
Plant-level Events are also included in NERC specifications, starting January 2024. Criteria matching these events are replicated in Drive as NERC-FO (Forced Outage) Events.
The NERC-FO event starts on the first timestamp where there are parallel events that are categorized as NERC Forced Outages across more than 20 MW of inverter or wind turbine capacity. This is based on the the NERC Performance marker Forced Outage Inverter Hours or Forced Turbine Hours.
The example below (from Chapter 5 of the NERC Data Reporting Instructions) shows a site with a Plant Total Installed Capacity of 100MW (A).
The event starts at 20MW (B), which is the result when the Start Plant Available Installed Capacity of 80MW is subtracted from the Plant Total Installed Capacity of 100MW.
The Nadir of the NERC-FO event, i.e., the Minimum Plant Available Installed Capacity for event is determined as the largest total capacity of inverters or wind turbines with NERC Forced Outage events.
The example below shows an Event Nadir of 25MW (C).
The end of the NERC-FO event occurs when 95% of the capacity at that Nadir has returned to service. This is again evaluated by Drive by summing the capacity for inverters or wind turbines with NERC Forced Outage events.
The event ends when the capacity reaches 98.75MW (D), which is the result when the product of the Event Nadir of 25MW (C) and the Minimum Plant Available Installed Capacity is subtracted from the Plant Total Installed Capacity of 100MW (A).
Note that the 95% end criteria refers to the nadir of capacity that has been offline for NERC Forced Outage events. It is not related to 95% of the plant capacity.
NERC has defined Cause Codes which indicate which equipment caused the outage. These can be attributed to any NERC-FO Event. The full lists of Cause Codes are defined by NERC:
Appendix J: Cause Codes
GADS Wind Turbine Generation (2024)
Appendix J: Cause Codes
Drive will establish an estimated Cause Code for all NERC-FO Events. This estimation is based on all parallel NERC Force Outage events at the inverters or wind turbines.
The underlying events are aggregated using the System/Component categorization. See Drive Events: Categorization for System & Component for details.
The System/Component with the highest cumulative energy loss (across the underlying events) is used to determine the most relevant Cause Code. The mapping between System/Component and Cause Code was established by Power Factors. Since both the System/Component and Cause Code lists were defined by NERC, there is most often a direct link.
There is a NERC-defined Potential Production MWH Loss which is calculated per event, per the NERC specifications. This is the sum of capacity lost during the period (MW Capacity loss multiplied by the duration of the event). It is shown as the green-shaded area in the example above.
Note that there is NO Drive Energy Loss Allocated (ELA) to these NERC-FO events, and they do not group with or interact with any other events in Drive.
In the Event Manager dashboard, customers can filter for NERC Plant Outage Events for a given reporting month at the Plant level:
Customers can view the Event Details for any NERC-FO event to see the underlying attributes supporting the start and end times:
NERC_AC_CAPACITY_IN_OUTAGE.CALCULATED6
This is the basis for the start and end times of the event.
NERC_AC_CAPACITY_AVAILABLE.CALCULATED
NERC_NUMBER_OF_GENERATORS_IN_OUTAGE.CALCULATED
The following attributes may also be viewed in the Data & Trends Historical dashboard at the Plant level:
NERC_AC_CAPACITY_IN_OUTAGE.CALCULATED6
NERC_AC_CAPACITY_AVAILABLE.CALCULATED
NERC_NUMBER_OF_GENERATORS_IN_OUTAGE.CALCULATED
6The NERC_AC_CAPACITY_IN_OUTAGE.CALCULATED attribute is the basis for the start and end time of the NERC-FO Event.
Links to relevant information on the NERC GADS website:
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