The wholesale folder provides access to a wide range of data relating to the operation of the wholesale electricity market. For example, final pricing raw case files, vSPD input GDX files, and CSV files containing final prices, half hourly metered data, bids and offers, and much more.
This folder provides access to datasets that relate to the operation of markets for ancillary services. Electricity markets require ancillary services to ensure the quality and reliability of the electricity supply is maintained at acceptable levels. Offers to supply frequency keeping services are an example of the data available to be downloaded.
This folder provides access to information and datasets relating to forward markets. For example, the weekly report summarising activity on the ASX New Zealand electricity futures and options exchange and the New Zealand electricity hedge disclosure system. Forward markets can take many forms, and enable parties to manage price or location risks by trading contracts derived from the spot market for electricity.
Environmental factors such as weather can significantly influence outcomes in the electricity market. This folder provides access to environmental datasets. For example, lake levels and inflows into hydro storage reservoirs.
This folder provides access to supplementary information that supports reports published elsewhere by the Electricity Authority. For example, the analysis undertaken to support a consultation project or an industry study.
vSPD is an independently audited, mathematical replica of the Scheduling, Pricing and Dispatch (SPD) market clearing engine used in the administration and operation of the New Zealand electricity market.
The Hydro Supply Security (HSS) test applies a deterministic methodology to calculate the risk of a storable hydro supply shortage by assuming that storable hydro is treated as the last resort supply of energy. The HSS test is encapsulated in a simplified version of the vSPD model.
Constraints in the SPD model fall into one of three categories:
• Branch constraints - a group of transmission lines between two locations combined into a single constraint
• Branch limits - a constraint on the transfer capacity of a single transmission line between two locations
• Market node constraints - restrictions on machines providing frequency keeping services.
Only the instances of the above constraints that are binding in the SPD solution for final pricing are presented in this report. A constraint is determined to be binding if its associated shadow price is positive. On any given day, there may well be no binding constraints of any or all of the three constraint types. Binding branch limits are quite rare.
Limit (MW) denotes the megawatt value of the transfer capacity parameter for branch constraints and branch limits, and the generating machine limit net of the frequency keeping requirement in the case of market node constraints (i.e. the right-hand side of the constraint).
Shadow price ($/MWh) is a measure of the cost to the system of a binding constraint. Conversely, a constraint that is not binding will have a zero shadow price and imposes no cost on the system. More technically, the shadow price represents the decrease (increase) in the SPD objective function value that would be associated with a 1 MW increase (decrease) in the limit of the constraint. Shading is set between zero (white), $100 (yellow), and $200 (red) on the shadow price as a visual cue indicating the severity of boundedness. Historically, approximately 80% of all binding constraints have a shadow price of less than $200/MWh.
The components that the constraint is composed of (i.e. the left-hand side) can be viewed by clicking on the plus sign at the left to expand the row:
• The factor represents the technical coefficient or parameter on each component of the constraint
• The MW value of each component denotes the value attained by the transmission flow variable for branch constraints and branch limits and the generating variable for market node constraints.
The sum (over all components) of the factor multiplied by the MW for each component will equal the limit or right-hand side parameter for a constraint that is binding.
If a branch or branch limit constraint spans two zones, the constraint will appear in the report twice; once for each zone.
Downloading the report as a CSV or PDF does not capture the components of the constraints. To obtain all details of binding constraints, including its components, and to select binding constraints for more than a single day, please use the underlying data report (icon at upper right of screen).
For more information on specific terms and their definitions please visit the glossary on this website.