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Overview

This section covers the use of Event Files in Apollo, including:

What are Event Files?​

Event Files are used to simulate temporary or permanent changes to the power system during a simulation. They allow users to modify the characteristics of specific system objects without permanently changing the system database.

Rather than editing the database itself, an Event File applies changes only for the duration specified within the event. This enables users to model planned outages, transmission constraints, renewable curtailments, capacity adjustments, demand changes, and other operational scenarios while preserving the integrity of the original database.

Event Files are commonly used during Historical Load, Backcasting, Forecasting, and What-if studies.

After completing this section, users should be able to:

  • Understand the purpose of Event Files.
  • Create a new Event File.
  • Understand the required Event File fields.
  • Apply Events to different system objects.
  • Configure common operational scenarios.
  • Create Event Sets for multiple Event Files.
  • Execute Event Files through Apollo or batch files.

Common Applications​

Event Files are frequently used to simulate operational changes that affect market dispatch and system performance.

  • Generator Outages Temporarily remove generating units from service by reducing their available capacity during a specified time period.

  • Transmission Constraints Restrict power flow across transmission interconnections such as VISLUZ1 and MINVIS1. This allows users to study congestion, regional price separation, and transmission bottlenecks.

  • Renewable Curtailment Increase or decrease the available capacity of renewable technologies such as Solar, Wind, and Hydro. This is commonly used for sensitivity studies and renewable integration analysis.

  • Market Studies Modify simulation parameters such as Short Run Marginal Cost (SRMC), Bid Prices, Bid Quantities, Demand, and Carbon Cost without permanently modifying the system database.

Creating an Event File​

Event files can be authored in two ways: through the Scenario Studio GUI in Suite, or by copying and editing the CSV file directly in a spreadsheet application. The two workflows produce the same file format — pick the tab that matches your setup.

Scenario Studio (GUI)​

  1. Navigate to the Scenario Studio Tab. Open Suite and go to the Scenario Studio tab where you will see the Create Event button at the lower right.
  2. Create a New Event File. A new event file can be created by appending to an existing one, merging multiple event files, or from scratch.
    1. Append to existing event file — Choose the event file from the dropdown → set the output Event filename → click Add Row to append your new event(s) → Save Event File when done.
    2. Merge existing event files — Add your event files → set the output event filename → Save Event File when done.
    3. New Event file — Set the output Event Filename → click Add Row to append your new event(s) → Save Event File when done.

Event File Structure​

Each Event File consists of seven primary fields:

FieldDescription
EIDUser-defined Event Identifier.
TypeSpecifies the object type that will be modified.
DUIDIdentifies the object affected by the Event.
StartTimeDate and time when the Event becomes active.
EndTimeDate and time when the Event expires.
PropertyDefines which attribute of the object will be modified.
CapacityValue assigned to the selected Property.

1. EID​

The Event Identifier (EID) is a user-defined identifier that uniquely distinguishes each Event.

Examples:

  • EV001
  • COAL_OUTAGE
  • VISLUZ_LIMIT

2. Type​

The Type field specifies which system object will be modified. Supported object types include:

TypeDescription
PoolEntire electricity market.
RegionMarket region.
LinkTransmission interconnection.
SiteIndividual generating site.
SitesMultiple sites based on Group classification.
SUnitSupply Unit.
DUnitDemand Unit.
StorageEnergy Storage System.

3. DUID​

The DUID (Dispatchable Unit Identifier) identifies the object that will receive the Event. The required value depends on the selected Type:

TypeRequired DUID
LinkVISLUZ1 or MINVIS1
SUnit / DUnitSpecific Unit ID
SiteSpecific Site ID
SitesBATTERY, BIO, CCGT, COAL, DIESEL, DISPDEM, GEO, HYDRO, MR ALL, OCGT, PUMP, or ROR
RegionCLUZ, CVIS, or CMIN
StorageSpecific Storage ID
Note

When using Type = Sites, the DUID refers to the Group classification, allowing the Event to be applied to every Site belonging to that Group.

4. StartTime​

Specifies the exact date and time when the Event becomes active.

Example: 11/25/2025 2:50:00 AM

5. EndTime​

Specifies the exact date and time when the Event ends. Once the EndTime has been reached, Apollo automatically restores the original database values.

6. Property​

Specifies which attribute of the selected object will be modified. Available properties depend on the selected object Type. See Property Definitions by Object Type below.

7. Capacity​

The Capacity field contains the numerical value applied to the selected Property. Its meaning depends on the Property being modified.

Property Definitions by Object Type​

Depending on the Type of object you are modifying, you can adjust specific properties in the Property field. Select an object type below to view its available properties:

Pool​

PropertyDescription
%SRMCPercentage multiplier for Short Run Marginal Cost (SRMC).
%BidPrcPercentage multiplier for bid prices.
MaxPrcMaximum (ceiling) market price.
MinPrcMinimum (floor) market price.
VOCEValue of Carbon Emissions.
WeatherWeather condition (HOTDAY, WARMDAY, NORMAL, COOLDAY, or COLDDAY).
DemScaleDemand multiplier.

Configuration Examples​

Here are practical examples of how to configure the CSV fields for common event scenarios:

Unit Outage​

To simulate a generator outage, set the Property to %MwCap and the Capacity to 0. This reduces the unit's available capacity to zero during the specified period.

EIDTypeDUIDStartTimeEndTimePropertyCapacity
05TPC_G0SUnit05TPC_G011/25/2025 2:50 AM11/25/2025 5:25 AM%MwCap0

Creating an Event Set​

If multiple Event Files need to be executed simultaneously, Apollo supports the use of an Event Set.

Instead of loading several Event Files individually, create a new CSV file containing a single column. Each row should contain the exact filename of an Event File.

Example:

MasterEventSet.csv
Ev_HISTORICAL.csv
Ev_VISLUZ1.csv
Ev_SolarExpansion.csv

When an Event Set is executed, Apollo processes every Event File listed within the CSV.

Best Practices​

To ensure reliable simulations and simplify maintenance of Event Files, consider the following recommendations:

  • Use descriptive Event IDs that clearly indicate the purpose of each Event.
  • Keep Event Files focused on a single scenario whenever possible.
  • Reuse existing Event Files as templates to maintain consistency.
  • Verify the Type and DUID fields before executing a simulation.
  • Ensure that the StartTime and EndTime accurately reflect the intended duration of the Event.
  • Use Type = Sites together with the appropriate Group classification (such as SOLAR or COAL) when applying changes to an entire technology class instead of modifying individual Sites.
  • Store related Event Files within an Event Set for complex studies involving multiple simultaneous system changes.
  • Review Event configurations before running a simulation to confirm that the expected objects and properties are being modified.

Running Events via Batch File​

When executing your simulation through a batch file, the command-line flag you use depends on whether you are applying a single event file or a grouped event set.

  • Single Event File (-e): Use the -e flag followed by the exact filename of your individual event.

    Single Event Example
    iPool.exe -o BASECAL -s BACK01 -e Ev_HISTORICAL.csv

  • Event Set File (-eset): Use the -eset flag followed by the filename of your Event Set CSV. This will instruct the system to run all files listed within that set.

    Event Set Example
    iPool.exe -o BASECAL -s BACK01 -eset EventSet.csv