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Retail

This folder provides access to datasets that relate to the operation of the retail electricity market.

Wholesale

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.

Ancillary services

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.

Forward markets

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.

Environment

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.

Supplementary information

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

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.

GEM

GEM, which stands for Generation Expansion Model, is a GAMS-based, long-term capacity expansion model of the New Zealand electricity sector.

Doasa

Doasa is a version of the stochastic dual dynamic programming technique applied to the solution of hydro-thermal scheduling problems.

HSS

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.

Reports > Wholesale

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Stress testing - summary

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Link to this report:

Notes:

  1. The spot price risk disclosure regime, commonly referred to as the stress testing regime, is described in Subpart 5A of Part 13 of the Code. Disclosing participants are required to apply a standard set of tests that assess aspects of a firm's financial position in response to changes in spot prices. Spot price risk disclosure statements are to be submitted on a quarterly basis to a person appointed by the Authority. That person then provides an anonymised summary of the disclosure statements to the Authority and it is these summaries that underlie this report.
  2. The Authority makes no judgement about the different levels of risk tolerance exhibited in the stress testing results. Adopting risky positions is a legitimate strategy and the Authority hopes that the stress test regime will help ensure that these sorts of positions are being taken by decision-makers fully conversant with the potential consequences. Decision-makers are accountable for the impacts of their decisions even in the event that they lead to financial distress during times of scarce supply.
  3. Three stress measures are defined: shareholder equity, cash flow and cover ratio. The cash flow measure is a ratio of the change in cash flow due to the nominated stress test over the last reported value for annual cash flow. The cover ratio measures the revenue received under the scenario relative to the costs incurred under the scenario. The shareholder equity measure is a ratio of the change in shareholder equity due to the nominated stress test over the last reported value for shareholder equity.
  4. Two scenario types are defined: energy shortages and capacity shortfalls. Financial stress is assessed following exposure to:
    • energy shortage events that might give rise to periods of sustained high spot prices, and,
    • unexpected capacity shortfalls that might arise for short periods due to high demand.
  5. The distribution of the anonymised stress testing results submitted by disclosing participants is summarised with a box and whisker plot for each quarter. The lower and upper horizontal edges of the boxes represent the 25th and 75th percentiles, respectively, or, alternatively, the first and third quartiles. Half of all results lie inside the box. The horizontal bold line dissecting the box denotes the 50th percentile or the median result. The horizontal bar at the end of the whiskers emanating from the boxes represents the minimum and maximum values, unless the designated bounds are exceeded in which case the whisker is truncated at the bound. Hovering the mouse over the results for any quarter will cause a tool tip to appear disclosing the values of the summary statistics. If the whiskers reach the designated bounds, the number of results beyond the bound is given. The value of outlier results is not revealed so as to guard against efforts at participant identification.
  6. A guide has been prepared to assist with interpreting the stress test results.
  7. Additional information about the stress testing regime can be found here. This information includes the purpose of the regime, what the stress test scenarios represent, and a set of answers to frequently asked questions.