Environment Discussions

API for SmartHome Load Curtailment Automation

2023-09-20T09:42:54.2170000

Hi all,
I'm looking to develop something for the NZ smart home community to use, that could respond to the grid when it is under stress. A way for smart homes to trigger home automation which shuts off non-essential systems in their homes when EMI/grid operators need it. i.e. stop EV charging, pool heating etc.
Something like the old ripple control system but for smart homes/modern times.

It seems that currently, the practice is to use social media and press asking people to reduce power. e.g. https://www.stuff.co.nz/business/132722172/transpower-says-power-supplies-tight-as-cold-snap-moves-up-country

Wondering if the the EMI's APIs are suitable for this, is there a better alternative or is there something already planned that would best provide this?

Thanks

Hydrological modelling dataset (HMD) - clarifications

2023-07-30T22:56:38.8630000

I would first like to thank EMI for the provision of the HMD dataset.

When I was having a look at this data for one of my projects, I came up with a few questions:

1. For Lake Taupo inflow, there are 5 different datasets with different site numbers - Actual, Natural, Linnear, Non linear and Opearational. This is also the same for a few different flows. Am I right in assuming that all the different datasets represent the same flow using different methods? If that is the case, is there a most up-to-date method which EMI suggests using?

2. As I was trying to understand how the data was put together, I did some analysis on Lake Ohau (this flow was chosen because it had inflow, outflow, storage, and spill data). Below is a small sample of the analysis:

The flow data is in reference to the left axis while the m3 quantity is along the right axis. The inflow is very closely correlated to the outflow. Also, the difference between the two has remained the same throughout the analyzed period at 12m3/s. Further, the spill is remaining the same at around 1.22 Mm3. Given these data, how is the storage data changing? When eyeballing it, it seems like when the inflow is increasing, there is an increase in storage (timeshifted by a few periods) but there is also an increase in outflow by the same amount. Even the spill data is not exactly explaining the change. Can someone please clarify this?

3. I went through this thread for understanding how Specific_Energy is derived. There seem to be two different types of specific energy data - Scheme and Single stage. What is the difference between the two?

Thanks in advance.

Data availability on active storage levels for lakes in New Zealand

2023-01-27T04:20:21.4630000

Hi Community admins and members,

EA's trading conduct report shows storage levels for the years 2021 and 2022 here

I am wondering if data on active storage (Mm3) and lake level(m) for the years 2021 and 2022 are available? I can only view the data for these two indicators made available for lakes upto end 2020 on the EMI platform.

Thanks in advance!

Best,
Ashish

Benmore inflow data

2021-09-28T21:46:52.0800000

Hi,

The time period of Benmore inflow series 98615(2) in the csv file is 31/12/1931 24:00:00 - 30/12/20 24:00:00, but in HMD Report 2 it is 01/01/32 - 31/12/20. I wonder if the record dates in the csv file are correct.

Regards,

Ziming

Waikato tributary inflows difference

2021-09-30T04:13:24.1030000

Hi,

There are differences between the Arapuni trib flow 92724(1) series and the total of derived tributary flows from Aratiatia to Arapuni. There are differences between the flows calculated using the Arapuni trib flow and tributary factors and the derived tributary flows for Aratiatia to Arapuni respectively.

Regards,

Ziming

New release of EMI dataset – Full update of the hydrological modelling dataset (data to 31 Dec 2020)

2021-07-28T23:30:58.1670000

The Authority has released an update of the Hydrological Modelling Dataset (HMD) that includes data to the end of 2020. This release is a full update of the dataset revisiting the historical records and correlations. As 2021 has reminded us, an appreciation of the significance of hydro generation and the inherent variability of hydro inflows is fundamental to understanding the electricity market, managing security of supply, and planning the New Zealand Electricity system. The HMD provides detailed information that supports the efficient operation of the market, monitoring and policy development, and planning as NZ transitions to a 100% renewable system that delivers for consumers.

The HMD includes the following datasets:

Infrastructure and hydro constraint attributes (including access to contingent storage)
Flows (including inflows, outflows, tributary flows, and flows at a junction or point)
Storage and spill information

This release includes the following enhancements:

Historical spill data is now available at daily resolution aligning it with information in other datasets
A flow series for the natural Lake Onslow inflows has been added to support any modelling of potential schemes

More information is available in the reports included with the HMD. Users of the dataset are encouraged to post feedback - especially if they believe there is an error or something has been missed in the infrastructure and hydro constraints file.

The Authority appreciates the ongoing cooperation of the hydro generators and other data providers in compiling and publishing this dataset.

EMI dataset updated – Interim update of the hydrological modelling dataset (data to 31 Dec 2016)

2017-10-26T23:21:27.7370000

We’ve published the latest hydrological modelling dataset (HMD) including data to the end of 2016.

The HMD includes:

infrastructure and hydro constraint attributes (including access to contingent storage)
flows
storage and spill information.

Due to the high proportion of hydro generation in the New Zealand electricity system, a good understanding of hydrology is required for many functions.

1. Operationally, this data is used heavily within the industry to inform planning and decision making related to the inherent uncertainty of hydrology, i.e. the timing and volume of energy supply from inflows to the broader electricity system. The information may be used as inputs into studies employing tools such as DOASA, a hydro-thermal scheduling model which seeks to optimally dispatch hydro resources.

2. The dataset holds an accurate record of hydro data that assists monitoring market outcomes as well as providing important historical context to observed market responses. In addition, this information is used to assist in the calculation of the security standards for energy and capacity.

3. Broader studies around possible future scenarios for the New Zealand electricity system are also enabled through the use of this data.

We continue to improve the organisation of the dataset to avoid confusion and errors in the use of this data. These changes mean that file names or formats may have changed slightly from the previous dataset. This year we have included an index file with each set of files to assist users in interpreting the data.

This update is an interim update meaning the 2016 year has been appended to the existing series. Next year we intend to undertake a full update. This update will entail revisiting historical correlations.

Users of the dataset are encouraged to post feedback - especially if they believe there is an error or something has been missed in the infrastructure and hydro constraints file.

The Authority appreciates the cooperation of the hydro generators and other data providers in compiling and publishing this dataset.

Enhanced report on EMI – Historical electricity risk curves

2021-07-12T22:00:04.1600000

The historical electricity risk curve report has been enhanced to provide a comparison of hydro storage (updated daily) against the full set of risk curves, boundaries, and triggers first established by the system operator in 2019.

The following curves are now available via the show parameter:

Risk status curves (default)
Percentage risk curves
Contingent storage release boundaries
Official conservation campaign triggers
All curves, boundaries, and triggers (enabling a comparison of various curves)

The figure below shows the risk status curves for New Zealand. The full collection of risk curves for New Zealand and the South Island are available in a public dashboard.

Historical electricity risk status curves

The data for the risk curves is available for download as a daily series via the data tab. This is a change from the previous report which only provided data on a change or at monthly resolution. The change brings all the data in the chart to daily resolution. For more information on the report see the more information tab.

Members can add this report to their own dashboard by hitting 'Add to my dashboard' at the bottom right, or 'Follow' the public dashboard to add this to their own dashboard menu.

Changes to the percentage risk curves over time are highlighted in several other public dashboards.

For more information on the electricity risk curves and the assumptions behind these see the system operator's website.

Forward Looking Climate Change Outlook

2021-05-07T01:14:17.8800000

Im new to EMI and interested in the tools available and just getting up to spped still however a question Im interested in.

Now we are progressing toward climate change commitments shouldnt the Electricity Authority be an enabler for ensuring that we can develop more comprehensive understanding of the effects of decisions in our electricity market and how we can do better in terms of our own environmental management and future energy mix.

As an example if hydrogical, irradiance and wind data was presented then couldnt we then retrospectivily analyse the impact that different mix of renewables would have on our lake levels and therefore electricity prices. While this sort of data can be locational it would allow some assessment based on averages to begin happening better informing our generators and markets participants of potential opportunities for future strategy toward meeting climate targets?

Anyway just a random thought..... what do you think?

Inflow data download

2018-11-14T22:41:43.0200000

Is there anyplace to download a hydro inflow dataset, say daily data? I see the “flows” datasets on emi, but that is a lot to wade through. I’m looking for something simpler like the graphs on the Transpower site here, but in .csv or similar and more back history if possible. Cheers.

Average hydro spill per month

2019-07-07T22:37:15.8200000

We have great graphs showing average lake levels per month over a number of years, as well as inflows.

Are there similar graphs or information showing average hydro spill per month at a national level?

Generation capacity (MW) of North Island's hydroelectric and geothermal power plants

2020-04-23T13:18:43.9700000

Hi,

I would like to get a citable information of the capacity of North Island's hydroelectric and geothermal power plants. I found a bit outdated summary on wikipedia (see below), but I would like to use more up to date data.

Thanks

https://en.wikipedia.org/wiki/List_of_power_stations_in_New_Zealand

Hydro Storage Data

2019-11-22T12:59:24.8000000

Dear Sir or Madam,

I am wondering whether it's possbile to get historical and up-to-date Hydro storage data to download.

As I went through this forum and other websites, i got a feeling that it's impossbile to get it for free. Therefore, i am willing to pay to subscribe a good data source, but still unable to find one. Asking for your help here, thx in advance.

Actually the data i am looking for as below, every week Transpower announces this kind of data:

Best regards,

Paul

EMI dataset updated – Full update of the hydrological modelling dataset (data to 31 Dec 2017)

2019-01-22T04:18:27.3430000

This update has taken some time to get to, but we have published the latest hydrological modelling dataset (HMD) including flow data to the end of 2017. The 2017 year was noteworthy with very low late winter inflows contributing to controlled storage crossing the one and two per cent risk curves.

The HMD includes:

• infrastructure and hydro constraint attributes (including access to contingent storage)

• flows (including inflows, outflows, tributary flows, and some river flows)

• storage and spill information.

Due to the high proportion of hydro generation in the New Zealand electricity system, a good understanding of hydrology is required for many functions.

1. Operationally, this data is used within the industry to inform planning and decision making related to the inherent uncertainty of hydrology, i.e. describing the timing and volume of energy supply from inflows to the broader electricity system. The information may be used as inputs into studies employing tools such as DOASA, a hydro-thermal scheduling model, which seeks to optimally dispatch hydro resources.

2. The dataset holds an accurate record of hydro data that assists with monitoring market outcomes as well as providing important historical context to observed market responses. In addition, this information plays a key role in the calculation of the security standards for energy and capacity.

3. Broader studies around possible future scenarios for the New Zealand electricity system are also enabled through the use of this data.

We continue to improve the organisation of the dataset to avoid confusion and errors in the use of this data. These changes mean that file names, descriptions, or formats may have changed slightly from the previous dataset. We’ve again included index files in each folder, and this year have published derived tributary inflows for the key reservoirs in each modelled hydro scheme.

This publication is a full update of the dataset and has revisited rating changes and historical correlations. For more discussion of the differences please see the accompanying reports: Report 2a Flows comparison, and Report 3a Storage and spill comparison.

Users of the dataset are encouraged to post feedback - especially if they believe there is an error, a better method for accomplishing the same end, or if something has been missed in the infrastructure and hydro constraints file.

The Authority appreciates the cooperation of the hydro generators and other data providers in compiling and publishing this dataset. At this time we are unsure if we’ll get to an HMD update for 2018 flow data, although we will maintain the infrastructure attributes as we are made aware of changes.

How do I convert hydro inflow data from cumecs to GWh/day?

2016-08-03T04:49:38.7600000

This is not as simple as you might think – conversion factors can change due to:

changes to the infrastructure (rerunnering, draft tube modification etc),
consent changes allowing different lake levels or flows (higher or lower head, different minimum flow conditions etc), or
even changes in operational regime (operating more or less time at the peak runner efficiency, higher or lower head etc).

The hydrological modelling dataset (HMD) records these changes through time for the main hydro sites. This information is recorded in the infrastructure and constraint attributes file. We work together with generators, the system operator and Opus to maintain this record.

As a user of this information, you need to consider where your interest lies. Are you interested in:

the energy from inflows (or storage) to an individual stage in a hydro scheme, or
the energy from inflows to the entire hydro scheme assuming that all the inflows can be captured and used for generation.

It is worth noting that individual hydro schemes can have multiple owners or participants managing the generation stations in the scheme.

To make this easy we have derived the specific energy of water for each reservoir or catchment considering both the energy produced by the single stage and for the entire scheme. The specific energy, as we have used it, is the electrical energy that one (1) cubic meter of water can generate and provide to the electricity system.

Let’s use Taupo as an example to convert average flow from cumecs to GWh/day

A cumec is a volumetric flow rate; it is one cubic metre per second (m3/s).

From the file ‘Specific_energy_(derived_for_scheme).csv’ you can filter by 'site' to yield Taupo (TPO) data. A range of values exist for specific energy that have been derived from the infrastructure and hydro constraints data. Each value represents a distinct set of conditions, and these values are recorded with start dates and end dates.

The current value is recorded with no end date – for our TPO example, it is 0.6865 kWh/m3.

So, if the average flow rate for a day into the Taupo reservoir is 100 m3/s, then a volume of 8,640,000 m3/day would have flowed into Taupo on that day. Multiplying this daily flow volume by the specific energy gives us a flow of 5.9 GWh/day.

We are interested in receiving feedback on the HMD. Please let us know if anything is unclear or you notice any errors or omissions.

Hydro risk curve data

2018-02-26T00:53:07.7000000

I'm keen to download a csv of the hydro risk cruve dataset.

The the link to download the CSV is constructed from a bunch of parameters (see below):

https://www.emi.ea.govt.nz/Environment/Download/DataReport/CSV/3UN1KD?
EffectiveDt=20180220&
RegionCode=NZ&_
si=p|0,
v|4,
_dr_
EffectiveDt|20180220,
_dr_RegionCode|NZ,
_dr_seriesFilter|1%2c2%2c4%2c5%2c6%2c7%2c8%2c9%2c10%2c11
&seriesFilter=1,2,4,5,6,7,8,9,10,11

Are there any details on how those parameters work? Can I leave at least some of them blank so that the 'latest' effective date data is presented?

EMI dataset updated – Interim update of the hydrological modelling dataset (HMD)

2016-05-23T03:55:08.1200000

Late last year we published the inaugural HMD on the EMI website. We are grateful to those participants who assisted us by providing data, feedback and advice.

The HMD replaces the so-called Spectra dataset that the Authority previously published every two years. More importantly, it extends the available data beyond inflows. For example, the HMD includes information on storage, spill, and resource consents. Timely hydrological information is important for making well-informed investment and operational decisions, policy, and for monitoring security of supply. The latter is particularly topical given the recent and proposed thermal plant closures.

We are also progressing standardisation and alignment of key parameters, such as plant factors, across the various uses of hydrological data, e.g. the determination of hydro risk curves by the system operator and the conversion of flow rates to energy in the NZX Hydro (NIWA) dataset.

We have retained OPUS International Consultants to undertake an interim update to append 2015 data to the dataset we published last year. Accordingly, we have once again requested assistance from the relevant participants. In the future, we propose to undertake an interim update annually with a full update, including a review of the historical correlations series, every two or three years.

We would welcome your feedback, so please post below or contact emi@ea.govt.nz if you have any questions or comments.

HMD on EMI website