Issue 43 - System Operator Newsletter

Simultaneous Feasibility Testing (SFT) Update

This project went live as planned on 28 March 2011.  We have published the SFT Implementation Go-live Status Summary in the Related Information section of the SFT Implementation project page.  The SFT Implementation project page will be moved to the completed project page under the market tab at the end of June.

Load Forecasting Project

Transpower has initiated a project to undertake improvements to our operational load forecasting model.  The load forecasting model provides a load forecast horizon of 7 days to 30 minutes ahead of real-time.  We use the forecast for system operation, and as an input to a number of market schedules, such as the schedule of dispatch, prices, and quantities (SDPQ), and the security dispatch schedule (SDS).  The forecast will also be used to call demand response contracted through grid support contracts (GSCs).

The project is being undertaken for a number of reasons, including seeking to explore what is possible in terms of improving our market and security forecast accuracy.  This is as part of a continuous improvement to systems, as a reasonable and prudent system operator, and in light of expectations that increasing distributed generation and demand response to price will make forecasting more challenging  – for example, with the advent of demand side bidding and forecasting (DSBF).  A further reason for undertaking the project is to support the Transpower demand side initiative (DSI) grid support contract.  We are responsible for operating these, and our operation can be made more efficient, and support grid security, through a better load forecast.

The general approach to the project is to conduct a proof of concept trial with a number of potential providers, and from that, select the most appropriate provider based on their forecast accuracy and cost.  Transpower is intending to hold the trial in the latter part of 2011, and over the summer of 2011 and 2012.

Further updates will be provided in future newsletters.

Reporting on use of Discretion to Constrain on Generation

We are aware that participants have a concern over the lack of visibility when the System Operator is using discretion to constrain on generation.  We have been in discussion with the Electricity Authority regarding options available to provide this information to the market.  One of the options raised was the creation of an automatic notification that would advise participants that the System Operator was using discretion.  It is proposed that this notification would include the MW that have been constrained on and the node to which the discretion applies.  We have contacted generators seeking their agreement to publish the node to which discretion applies as this will identify the generator that is being constrained on.  If participants do not provide their agreement then we will discuss the possibility of a Code change with the Electricity Authority.

Another option being considered is to make available to participants the System Operator daily report that is provided to the market administrator under clause 13.102 of the Code (this would be in addition to the proposed automatic notification above).  This report is required to include any situations where discretionary action under clause 13.70 has been used.

In the interim, we will send a customer advice notice (CAN) to advise the market when any of the Otahuhu, Southdown, Huntly or Whirinaki units have been constrained on.  The notice will include the initial MW constrained on and the start and end times for use of discretion.

Under Frequency Management Project (UFM)

The UFM project’s objective is to review the current under-frequency management products, operating practices, and frequency standards and to recommend changes where appropriate.

The project is made up of three work streams; instantaneous reserves, Automatic Under Frequency Load Shedding (AUFLS), and Asset Owner performance obligations (AOPO’s).  All three work streams are being carried out concurrently.

The AUFLS work stream reached a major milestone in April with the completion of the AUFLS Market Options workshop. The workshop was planned to address issues raised by industry participants during the first stage of the AUFLS review; the main question to answer was the options for commercial arrangements for AUFLS provision.

Various participants from industry came together in Wellington to discuss the pros and cons of three potential commercial mechanisms. The workshop enabled the different perspectives of industry to be heard and taken into consideration as the next steps are developed. The summary of the discussion will be circulated to participants and next steps will be included into the AUFLS report.

The UFM project as a whole is nearing another major milestone. The next steps of the project are to finish the technical and economic review for each work stream and organise the findings into a report. The results will be presented to industry in July.

Transient Stability Analysis Tool (TSAT)

In February this year we installed and implemented new software for performing transient stability analysis (TSAT).  In study mode this application allows us to carry out transient stability, damping, voltage and frequency studies on network powerflow save cases.  The TSAT application will help us:

• determine and understand the effect on transient stability of new grid equipment prior to commissioning;
• determine the effect proposed grid equipment outage combinations have on transient stability prior to outage approval to ensure power system security of supply;
• provide the ability for study post fault dynamic voltage recovery taking into account load dynamic;  (thus allowing the scheduling of dynamic reactive power research in critical regions such as Auckland, Wellington and Christchurch)
• meet our principle performance obligations and operate the power system in a secure manner;
• assess TSAT's suitability as a possible future replacement for the current Reserve Management Tool
• allow a smooth transition to provide online/real time transient stability analysis in a subsequent project if required.

Reserve Management Tool (RMT) Engine Upgrade

The RMT engine upgrade was completed at the end of February and was in the testing environment for a month before going live on 5th April.

The upgrade replaces the original MATLAB 5.3 from 1999 to the newest Matlab version R2010a. The upgrade was done by the Auckland University of Technology and assisted by SO Investigations.

This project means that the RMT engine is now fully supported and the System Operator now has a recognised software support for this tool.  The upgrade did no changes to the original code.