DC Lines

A DC line describes a connection for transferring energy between two areas.

        flowchart LR
  inext(External json input)
  inth5(Cap_file.h5)
  model(Model / API)
  inext --> model
  model --> MASKENETT.DATA
  model -- "optional" --> inth5
  inth5 --> LTM
  MASKENETT.DATA --> LTM
    

Figure 1: Dataflow for a DC line, staring from external data, ending in the LTM Core

Input

The API expects input data to be given as a list of “dclines” objects. Each object must have:

• name: string, must match the name given in the connection object

• forward_capacity: object, described in the Capacity chapter

• backward_capacity, object, described in the Capacity chapter

• loss_percentage: float, given as percentage

• forward_cost: float, cost of exchange in forward direction given in percent

• backward_cost: float, cost of exchange in backward direction given in percent

Example input:

{
    "model":
        {
        "dclines": [
            {
                "name": "DC_A",
                "forward_capacity": {
                    "timestamps": [
                        "2024-01-01T00:00:00Z",
                        "2024-01-01T10:00:00Z"
                    ],
                    "values": [[2], [3]]
                },
                "backward_capacity": {
                    "timestamps": [
                        "2024-01-01T00:00:00Z"
                    ],
                    "values": [[4]]
                },
                "loss_percentage": 2.1,
                "forward_cost": 2.2,
                "backward_cost": 2.3
            }
        ],
        "connections": [
            {
                "from": "numedal",
                "to": "DC_A"
            },
            {
                "from": "DC_A",
                "to": "tev"
            },
        ],
    }
}

Figure 2: Example input for a DC Line. The first object “dclines” describes the line itself, and the second object “connections” describes how the line is connected to the busbars. Note on line 9 - 10, a ten hours timestep is defined. This will be converted by the API to an hourly resolution in the Cap_file.h5.

Output

The output of the dcline` object is written to MASKENETT.DATA and optionally Cap_file.h5` if the capacity is given as a timeseries. This will be described in the capacity chapter.

Loss and Cost

The input contains three parameters describing the transmission loss: loss_percentage and costs: forward_cost` and backward_cost. These parameters will be written to “MASKENETT.DATA”.

Capacity

The forward_capacity and backward_capacity for a given line is defined by a timeseries with either a constant or several values. If both forward_capacity and backward_capacity are given as constants (timeseries with one value), the resulting capacity data will be written to MASKENETT.DATA. Else if either one of the capacity timeseries contains two or more values, both time series will be written to Cap_file.h5 as timeSeries data, with a reference flag in the MASKENETT.DATA: “>Capfile”.

The API supports any time resolution larger than one hour. The LTM Core however, only supports weekly, daily or hourly time resolution. The API therefore calculates the time resolution needed, based on the input. E.g. if the input series has a timestep of 3 days, then a daily resolution will be used. If a smaller timestep than an hour is provided, a warning will be produced, but the validation will not fail. If one of the input capacity timeseries is constant, a weekly resolution will be used for that timeseries.