Grid
The Grid is the physical design of the lines and nodes.
The grid is modelled as a single line between nodes, therefore if the physical grid has more than one line, this needs to be reflected in the values associated with the line. The physical aspects of the line, Resistance and Reactance are modelled to determine losses. Lines limits can be applied using 'Enforce' so constraints can be modelled.
Grid Details Box (top of the window)
| Name and Description | Used to identify and describe the Grid Resource |
| Base Voltage | Determines the variable losses that occur on a line through the formula: Loss = RZ2 / Base Voltage, where R is the per unit resistance of a line and Z the power flowing through the line in MW. |
Grid Lines Box
The Grid Lines Box provides access to details of the Lines connecting Nodes on a Grid. Lines can be added to, or removed from, the Grid Instance and their details edited.
Note: Within EMarket positive line flow (Node from to Node to) is an arbitrary convention. EMarket automatically adjusts for line flow direction at run time.
Line Box Fields
| Line Name | Automatically produced from Node From and Node To fields |
| Node From | The code of the Node defined as the upstream Node when line flow is positive |
| Node To | The code of the Node defined as the downstream Node when the line flow is positive |
| Resistance | The per unit resistance of the line |
| Reactance | The per unit reactance of the line |
| Winter Limit (MW) | The maximum capacity of the line during the Winter period |
| Summer Limit (MW) | The maximum capacity of the line during the Summer period |
| Enforce | When set to Y the Line capacities are enforced during Runs. When set to N, EMarket runs with the Line unconstrained which means that the power flow can exceed the limit values in this table. |
The Check Grid Configuration Button is used to ensure that all Nodes listed in the Grid Nodes Box are connected to the Grid and that there aren't any duplicate lines. An error message is returned if the Grid is not properly connected.
Grid DC Lines Box
The Grid DC Lines Box is used to set the limits on DC Lines (principally for the HVDC link).
DC Lines Box Fields (Fields which are identical to the lines box have been omitted)
| +Limit (MW) | The capacity of the line when the power flow is positive |
| -Linit (MW) | The capacity of the line when the power flow is negative |
Note: Lines appearing in the DC Lines Box cannot also appear in the Grid Lines Box. You will be prevented from saving a Grid with Lines duplicated in this manner.
- Comments
- Nodes need to be present before a line can be entered
- Individual line limits can be modified for defined periods using the schedule
- Individual lines can be entirely 'outaged' through the schedule
- Data can be copied directly from excel cells into cells in EMarket