Time Step Simulation: Setting up Scheduled Input Data

There area two types of input data for the Time Step Simulation:

Time Point-Based Data, which is described in the Loading Input Data section; and,

Scheduled Data, which is specified for data that more naturally spans multiple time points rather than being defined at each time point. In this section we describe how to specify this type of input data.

Although it is possible to specify the operating conditions of a power system exclusively by quantities at each time point, there are several quantities whose specification would be redundant and would require significant memory storage if defined in this manner. Examples of such quantities are:

The status of a transmission line that is taken out of service on a particular date and time for maintenance.
The status of a generator, which follows a particular maintenance schedule.
A generator’s voltage set point that is different during the day or at night.
A scheduled transaction between to areas that has different MW set points applied at 10 am, 4 pm and 10 pm.
A capacitor connection status for a Mvar block that is used only during the day.
An industrial load that operates at different levels for different shifts.
A peaker generating unit that operates only during certain hours of the day
Any many others

All of these quantities can be specified by introducing the concept of Schedule. A schedule is a list of pairs (Date Time, Value), where the value can be numerical, conditional (Yes/No or Closed/Open) or text. The Schedule can have any number of time points and can be periodic. The schedule defines the "shape" of how a quantity varies in time. In order to define a schedule, go to the Schedules sub-page of the Input page, right-click on the grid and select Insert New Schedule to bring up the Schedule Dialog.

Once a schedule has been created, we can assign an object field, such as the status of a transmission line or the MW output of a generator to the schedule by means of a Schedule Subscription. The object field will follow the schedule "shape" in time. The use of Schedule and Schedule Subscription objects gives us great flexibility in specifying how quantities should vary. In particular, it is possible to assign many fields to the same schedule. In order to define a Schedule Subscription, go to the Sched Subscriptions sub-page of the Input page, and right-click on the grid and select Insert New Subscription to bring up the Schedule Subscription Dialog.

An important feature of the Schedules is that their date/times do not need to match the date/times of the list of time points (time points listed in the Summary page). Suppose that your list of time points are defined hourly for the next day: 1am, 2am, etc. up to 11pm. You can schedule a particular action to take place at 2:35 am and see the results of that action in the next time point, i.e., 3 am. A special logic takes care of applying scheduled actions at appropriate time points asynchronously.