This page lists questions, answers and feedback received about the HVDC project and test programme.
|For the 700MW Pole 3 north flow 24hr thermal test, given thermal plant will need to be shut down, will this occur in the weekend?||We will take advantage of prevailing hydrology and market conditions in scheduling tests. Therefore, the 700MW test could occur at any time of the week. We may not require thermal plant to be completely shut down for this test.|
|Can we have a detailed sequence of tests that must occur with details of: duration, those that can be carried out with pole 2, and those that must be done as a monopole?||
Our scheduling will be dynamic to take advantage of prevailing hydrology, market conditions and tests completed to that point. For this reason we cannot provide a detailed sequence this far in advance.
We will, closer to the times of the tests, provide weekly test plans with expected timings and daily schedules with actual timings. We will be providing the test plan with details of transfer levels, expected durations and configurations by 20 July 2012.
|Do you have a test window where the tests requiring the thermal plant are bundled to reduce costs? What days will Transpower require the thermal plant so we can ensure that there will be resources available?||As our approach is to schedule tests dynamically, we do not have test windows at this point in time. That being said we are currently considering contestable availability contracts should we see a need to contract thermal availability|
|Will Transpower provide waivers for setting TPM HAMI peaks during test periods?||If the peak relates to generation from that participant that has been contracted by Transpower, then yes, this will be treated as an exceptional operating circumstance (EOC) under clause 34 (2) of Schedule 12.4 of Part 12 of the code. This relates to injection changes to support grid commissioning. If the HAMI does not relate to a test for which that participant has been contracted then the HAMI peak will not be waived.|
|What's the duration of Pole 2 outage and when will we know the Pole 2 outage dates?||The Pole 2 control system replacement only takes about four weeks, but this is followed by a series of Pole 2 commissioning tests similar to the commissioning of Pole 3. Once we are satisfied with Pole 2 performance we then run a series of Bipole tests to prove integrated performance of Pole 2 and Pole 3 control systems working together. From the start of the Pole 2 outage until completion of the Bipole tests we expect this to be approximately 3 months. We expect to confirm the Pole 2 dates by the end of July 2012.|
|What tests need to be completed for Pole 3 to be considered fully commissioned?||
Fully commissioned” means fully commissioned from a regulatory perspective, which means delivery of the Pole 3 converter station capability promised in the approved investment proposal for the project. To do that we need to complete successfully a 700 MW transfer test and all pre-requisite tests for that. The 700 MW test will be a north transfer test.
|Why does the test programme include north transfer tests up to 1000 MW (overload tests)?||The design overload capacity of Pole 3 is 1000 MW. If it is possible to achieve the overload tests within the Pole 3 commissioning budget then we believe we should do that in order to release the benefits to the industry and the country of having that extra capacity available. The overload tests are of short duration (30 minutes) and we expect they will be scheduled very close together.|
|Do you have enough time to get all the tests done?||Yes. Some tests will be run concurrently and there is a two week “overflow” period at the end of the programme. Hydrology will have the largest impact on progress through the test programme.|
|Will you require generating plant to shut down?||The grid owner cannot require any generating plant to shut down. Transpower will only be entering into market transactions aimed at incentivising behaviours that are likely to achieve the necessary HVDC link flows for the tests to occur. Some of those behaviours will be reductions in generation.|
|Are further project delays possible/likely?||We are confident we will meet the timeline for Pole 3 commissioning. We certainly have no reason to believe there will be any further delays, particularly as the issues we had with the control system testing are behind us.|
|Concerned about timing of bi-pole outages.||Transpower to provide outage schedule with test schedule.|
|Several power stations are being commissioned at the same time.||
We are aware of a number of large grid projects and generation projects all occurring within the coming year. Our detailed planning will take account of this as best we can.
|Who has liability if tests trip generation?||Tests are unlikely to cause tripping however any event would follow the process within the Electricity Industry participation code for the SO to follow to determine the cause of any under-frequency event.|
|Tekapo canal outage Dec to Feb 2013.||We note the potential interaction but we don’t anticipate this making a material difference to the overall commissioning of Pole 3.|
|Can we use Pole 3 at higher than tested levels for short durations, ie to cover loss of Pole 2 during round power? This would save reserves costs.||
No. Pole 3 levels will be defined within the test schedule and these levels will not be exceeded until Pole 3 has passed a system test at this level.
|Demand side for reserves – is there some physical work needed?||We are not aware of individual’s specific circumstances, however there are requirements that a provider must meet in order to be able to offer reserves. This is best discussed directly with the System Operator.|
|We need to know HVDC capacity at various stages.||Will add capacity and outages to timeline and the detailed testing programme will be advised through the CIAG.|
|Will add capacity and outages to timeline and the detailed testing programme will be advised through the CIAG.||We will be discussing this with the EA.|