Extended Reserve FAQ

Questions 1-15 were received during the Efficient Procurement of Extended Reserve workshops held on the 10th and 12th November 2015.

Questions relating to testing of AUFLS systems


If one AUFLS system triggers multiple circuit breakers, which of the circuit breaker times should be passed on (slowest, quickest, and average)?

The proposed total operation time requirements within the technical requirement schedule lie with the AUFLS system as a whole. The total operation time is observed from the time when the frequency pick up is met till demand is shed by the system.

In the case where multiple breakers shed the load the total operation time will be observed from the time the armed block frequency pick up is met till all the AUFLS demand  is shed by the system (i.e. all breakers open).  This means the slowest breakers will most likely set the total operation time, all breakers that are part of the system should be observed for testing.


Will there be any testing requirements for the flexible service (this includes remote arming/panel arming/manual arming)?

At this stage no additional testing is required. The system operator is considering if any additional testing requirements are needed should the flexible service be made available through the selection process.


Can a checklist be provided for completing testing?

Yes a check list similar to the commissioning of generator assets will be made available for compliance with extended reserve commission and testing. This check list will be discussed in the development phase of each implementation plan.


Do the end-to-end testing requirements require participants to trip circuit breakers and/or drop load? What are the alternatives?

The end-to-end testing should prove the total operation time of the AUFLS system.  This can be done by past records (or tests that are within the routine testing timeframe) that clearly demonstrate the devices and associated systems operation time. The tripping of the breaker under load is not a requirement if circuit breaker trip timing has been proven separately to the satisfaction of the system operator.  Some more clarity around this will be added to the Companion Guide following more industry discussion.


Does an AUFLS relay need to operate a circuit breaker directly?

No, there are no prescribed requirements as to how the AUFLS tripping scheme is to be designed. The impact on total operation time, maintenance testing and reliability of the AUFLS system should be considered if auxiliary devices are part of the design.


Is harmonic testing required for every relay type as equipment for harmonic testing is rare in NZ?

There is no clause in the technical requirement schedule that specifically states harmonic testing is required, just that proof of ability to operate as specified needs to be provided.

It is likely that harmonic testing will be an application test. If the impact of harmonic distortion on the device (firmware, version etc.) selected is unknown, testing is required. In the process of selecting equipment to provide the service the ability and types of testing required to prove compliance should be considered.


Will an acceptable measurement error of the relay be defined?

No, the error of modern relays is typically low and currently not considered a risk by the system operator. In the future should a device prove this assumption wrong, details will be added into the application section of the Companion Guide.


Under what conditions is type (or representative) testing acceptable?

If there are circumstances that require consideration of type representative testing this can be discussed and agreed with the system operator during the implementation plan stage. An approach similar to clause 14 of Appendix B of Tech Code A for specific devices may be considered - see page 67 of http://www.ea.govt.nz/dmsdocument/19214.


Can the Companion Guide for testing include options to demonstrate performance without dropping real load?

Yes, this requires input by industry to ensure practical and useful content is added to the Companion Guide. The flexibility and overhead of some of these options need to be investigated.


Should the hold time configured in the relay be included in the end-to-end operation time?

As mentioned previously the operation time begins from when the frequency pick up is met by an AUFLS relay and therefore the total operation time includes the impact of the prescribed hold time(s).

The hold time is used to mitigate mal operation and coordinate frequency elements. The system operator published report, AUFLS Stage V: Scheme Design, answers this question in more detail.


When should the first compliance report and test results be available?

The first compliance report should be available within 3 months of completing the related tests.


Can we provide a template compliance report?

Yes, with Industry’s help. Those willing to provide input, real test records and AUFLS diagrams to the template should get in contact with the system operator.


Will the SO approve a test methodology in advance?

No. The system operator may agree a test methodology at the Implementation Plan stage, however the Extended Reserve Provider must still ensure the test covers off all the requirements of the TRS and provides sufficient information for a compliance report.


Will there be an audit regime?

This is for the Electricity Authority to determine. [The system operator does note that elsewhere in the Code there are obligations towards “Records, tests, and inspections” which asset owners must meet Clause 8 of Tech Code A – see page 59.


Non-testing related questions


What is the process for providing AUFLS at the Grid exit point in the North Island?

Any requirements regarding utilisation of existing relays or provision of new relays at Transpower  grid exit points should be directed to the Grid Owner. Please contact Kent Murrell on 04 5906294 or kent.murrell@transpower.co.nz for further information.