EMO:Powerflow Case Concepts

Term	Definition
Powerflow	The electricity in MW flowing through a Transmission System Circuit
Powerflow Analysis	The process of calculating the energy flowing through each defined Circuit int he Transmission System using the electrical properties of the Circuits and the injection/off-take at each Node
Powerflow Case	The overall context for a single Powerflow analysis. It is the basic element associated with the Powerflow Data Source and is comprised of the Powerflow Case Definition and the Powerflow Case Output
Powerflow Case Definition	The set of input data required by EMarketOffer to effectively execute a single Run of the Powerflow engine model
Powerflow Data Source	A generic EMarketOffer Data Source providing access to output from Powerflow Case Analyses.
Powerflow Engine	EMarketOffer's DC Powerflow model
Powerflow Run	A single execution of the EMarketOffer Powerflow Engine using a specified Powerflow Case Definition to create a single Powerflow output data set
Powerflow Case Effective Date Range	Start date, period and the number of Periods for which Powerflow data is to be created (including first period). Be aware that Powerflow Case Definition works with a set of input data limited to seven consecutive days. A Powerflow Case Effective Date Range of 14 days will cause EMarketOffer to re-cycle the loaded Generation and Demand data for the second week of the Case. Transmission system data will however change correctly with calendar date beyond the 7th day
Swing Node	A Node to which energy imbalances are allocated during Powerflow analysis. Swing Nodes may be manually allocated by the user during Powerflow Case Definition or automatically selected while running the Powerflow Case.

More on Swing Nodes

When a Powerflow analysis is conducted, the profiled Generation and Demand figures from the Case Definition are used along with the Transmission System configuration to estimate flows in the Circuits. Any energy imbalance in the results is 'absorbed' at one or more selected swing nodes. When there is more than one Swing Node specified the imbalance is absorbed in proportion to the Demand at each of the Swing Nodes, e.g. if the imbalance is +20MW with two Swing Nodes carrying 60MW and 40MW, the first Node will carry +12MW of the imbalance and the second +8MW. This method allows the imbalance to be modelled by effectively ramping Demand up or down over a large region. If none of the Swing Nodes have Demand the imbalance is shared equally between the Nodes.

If none of the selected Swing Nodes are connected to the Transmission System in a Trading Period an automatically chosen Node will be used and an infeasibility message will be generated.

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