EMK:Entity.Traits

When a run is executed a set of binary files is created in a 'database' folder under the results directory (see Physical Architecture). These files are collectively called the Results database, and their internal structure reflects EMarket's Entity.Trait data model. This model captures EMarket's approach to data handling in which objects of interest - such as Generators or Nodes - are called entities, and the values describing an entity are its traits (e.g. Nodal Price or Generator Name).

An entity is a logical concept that represents a 'thing' about which EMarket needs to keep data. Things with similar modelling characteristics are classed under the same Entity type. In other words, Entities are typed by the object they represent in the 'modelled' world (e.g. 'Node' or 'Generator'). Different objects of the same entity type are called instances of the entity. So, for example, ABY and TKU are instances of the entity type: Node.

The characteristics describing an entity are its traits. In data handling terms it is the traits that differentiate Instances of the same entity type. The trait 'Node.Name', for example, differentiates the 'ABY' Node entity instance from the 'TKU' Node entity instance.

In EMarket entities and traits are given names that can be used to reference specific data items in the Run Definitions and their values in the associated output. Within a Run Definition Entity.Trait references can be used in any data entry field that accepts a formula expression (the Schedule and all Resource editors). The value of these expressions is calculated at run time and may vary significantly from Tick to Tick, especially if the formula refers to traits derived during the previous Tick.

Entity.Traits syntax: <entity>:<name of particular entity>.<trait>

E.g. Reference to the electricity generated by Generator: GEN01 for a specific period would look like this: Generator:GEN01.Generation

Warning: Entity.Trait references are case sensitive.

A complete list of EMarket Entity.Traits can be found in the Entity.Trait List below.

Special cases exist for the following Entity.Trait types:

Offer Band Entity

Offer Band entities must be referred to using the name of the Generator to which the Offers belong, as follows:

<OfferBand>:<Generator name>_<Offer type><Offer Band number>.<Trait>

where Offer type is E, FR, SR for energy, Fast reserve and Slow Reserve respectively.

Global Traits

Global Traits are user-defined variables that extend EMarket's Entity.Trait model. Global traits can be referred to in formulae in a similar manner as entity traits. Global variables can be defined through the:

• Run Window - through the Volatility Matrix, the File Data or MRJD features; or
• Schedule Window

The syntax for referring to Global traits is: Global.<Global variable name>

Demand Elasticity

Demand elasticity is controlled through an internal variable in EMarket. The syntax is: Region:<RegionName>.DemandElast

where RegionName is the name of a Demand Region defined in the Regions Resource Instance.

For example, if NI and SI are regions for your Run, their Demand elasticity might be given in the schedule as:

Variable	Definition
Region:NI.DemandElast	0.8
Region:SI.DemandElast	0.2

Note: Demand elasticity is defined as a proportion of the usual Demand, so a Demand elasticity setting of 0.8 sets the Demand to 0.8 of its usual value. The PieceWiseLinear function can be used to define the Demand elasticity.

Entity.Trait List

EMarket Entity.Traits are listed below. Traits marked with an asterisk (*) are either currently not used or are not accessible to users. Some traits should also be regarded as "read-only" traits, in the sense that their values are derived within the model and attempts to change the values are ignored. Such traits are indicated by a hashtag (#). Traits marked with a ^ are "static", that is, although their values are user-defined they cannot be altered during a Run.

Node

Region*	Region name if Node is defined in a Demand Region
Injection#	Total MW being injected at Node this Tick
Price#	Nodal price in $/MWh this Tick
Demand#	Total Demand off-take at this Tick in MW. Node.Demand represents the Demand - after the losses have been added
LocalDemand	Demand at the retail side can be accessed via the Node.LocalDemand trait
Resistance	the resistance between the retail supply Nodes and those on the grid
DirectDemand	Non-profile demand - i.e. an amount of demand in MW applied at a Node in addition to that calculated through the Demand Profile for the Node

ResRegion

RefNode*	Reference Node for the Reserve Region, e.g. HAY2201 for North Island of New Zealand
RAFFR	RAF for Fast Reserve Class this Tick
RAFSR	RAF for Slow Reserve Class this Tick
BaseRisk	Reserve Risk this Tick in MW
PriceFR#	Fast Reserve price this Tick in $/MWh
PriceSR#	Slow reserve price this Tick in $/MWh
ImportSubtractor	Where electricity is imported (via the HVDC) this quantity is subtracted from the risk represented by the import quantity.

Generator

Node*	Node at which Generator injects
Capacity	Maximum generating capacity in MW
CommDate	Commissioning date
MothDate	Mothball date
Outage	The proportion of capacity currently taken out of service
CurrentCapacity#	Current Capacity of the plant. Zero before Comm.Date and after Moth.Date, and also if the plant has an outage during the run
UnitSize	Unit size in MW. Used in determining the risk set by a Generator when modelling Reserves
Ramp_Rate*	Currently not used in EMarket
Generation#	This is the dispatched generation for the Generator in the current Tick in MW
Cost#	Aggregated cost of supplying energy and Reserve supply over all Offer Bands
ReserveCost#	The cost of Reserve provision calculated from the marginal costs for each Offer Band
Efficiency	Plant generation efficiency as a percentage
NonFuelMC	Non-fuel marginal cost in $/MWh
GenType*	Descriptive text only
FuelType*	Descriptive text only
Revenue#	Revenue earned by sales from generation and Reserve provision
PLSRSlope^	Used to determine the amount of Reserve that can be provided by a Generic Generator based on energy Offers. This trait is only accessible when the Dispatch Mode field in the Run Window is set to Nodal+Reserves
DispatchFR#	The quantity of Fast Reserve dispatched this Tick in MW
DispatchSR#	The quantity of Slow Reserve dispatched this Tick in MW

HydroStation

HydroRelease#	The amount of water (in cumecs), passing through a station. The figure includes spill
Hydrospill#	The amount of water (in cumecs) spilled by a hydro station
Diversion	Used to set the amount of water (in cumecs) that is diverted past a station. Care should be taken when assigning values to this trait, for example, when a large diversion figure (say 1,000 cumecs) is entered for a station at the head of a Hydro System. Although the model will make every attempt to meet minimum flow requirements for station downstream, if there is simply not enough water an infeasibility will occur and such things as negative system storages can result. Note that you can also enter negative diversion values and divert water into a station's reservoir.
MinGen	The MinGen trait defines a minimum generation in (MW) that the station must meet. It is not possible to control the minimum output of a hydro station that is part of a group.
MaxGen	Defines the maximum output of a hydro station in MW. It is not possible to control the maximum outage of a hydro station that is part of a group.
Inflows	The amount of water (in cumecs) into the reservoir
MaxStorage	Maximum storage capacity of a hydro reservoir in Mm3
HydroStorage#	The storage capacity of the reservoir in Mm3
MWperCumec	The conversion rate of the station in MW/Cumec
MinFlow	Minimum release of water immediately below the station in (cumecs).

OfferBand

Generator*	Name of Generator to which this band applies
BandNo*	Offer Band number
OfferType*	0, 1, 2 for energy, Fast Reserve and Slow Reserve respectively
InitPrice	The initial price set for the Offer in $/MWh. This can differ from the final price when Company Optimisation operating
InitQuantity	The initial quantity set for the Offer in MW. This can differ from the final quantity when Offer quantities exceed current capacity
Price	The price offered into the market in $/MWh
Quantity	The quantity offered into the market in MW
MarginalCost	The marginal cost of the Offer Band in $/MWh
Dispatch	The quantity of dispatch attributed to the Offer Band in MW
Cost	Dispatch * Marginal Cost (in $/hr)

Line

NodeFrom*	First Node defined at end of line
NodeTo*	Second Node defined at other end of line
Resistance^	Per unit resistance of the line
Reactance^	Per unit reactance of the line
Capacity	Forward capacity of the line in MW
RevCapacity	Capacity of the line in MW in the 'reverse' direction as defined by the line name
FixedLosses*^	Fixed losses in MW associated with the line, e.g. transformer losses
PowerFlow#	Power flowing on the line this Tick - can be either positive or negative
LM#	Lagrange multiplier for this Tick in $/MWh. This is the additional price differential across the line if it is constrained, i.e. at its limit. LM is zero when the line is unconstrained.

Company

Name*	Company's full
RetailCost#	Total retail cost for the Company this Tick in $/hr
RetailRevenue#	Total retail revenue for the Company this Tick in $/hr
ContractRevenue#	Total revenue/cost from all hedging contracts this Tick in $/hr
GeneratorCost#	Total cost of generation for the Company this Tick in $/hr
GeneratorRevenue#	Total generation revenue for the Company this Tick in $/hr
GrossProfit#	The total of revenues less costs above this Tick in $/hr
OptOn#	1 if Company optimisation is being done on this company, zero otherwise

Region

Demand#	Annual Demand in GWh at all Nodes in the named Region
DemandAdj	Load multiplier for the purposes of general load adjustment as a proportion, e.g. setting Region:<Region name>.DemandAdj to 1.13 in the schedule will increase overall Demand for that Region by 13%
DemandElast	Load multiplier for the purposes of modelling Demand elasticity. Applied as a proportion of the current Demand as per DemandAdj

Global

<user-defined variable name>

User-defined

Back to User Manual Main Page