Guest Post Written By Phil Helwig, P.Eng. (Retired)
Phil Helwig is a retired Engineer and Hydropower Consultant with over five decades of experience - much of it right here in Newfoundland and Labrador. He has been a frequent writer to the Telegram on the North Spur stability problem as well as on other issues including power reliability and security.
This is Helwig's first contribution to the Uncle Gnarley Blog. It is a timely one, too. In recent weeks readers have seen posts regarding the Phase I Report of the Public Utilities Board (PUB). It dealt principally with the findings of the Liberty Group's investigation into the root causes of DARKNL. In late August Liberty filed its Report on Phase II of the PUB's mandate which includes consideration of security and reliability issues in the post-commissioning of Muskrat Falls. Phil Helwig has now distilled this Report and comments on the concerns of the Liberty Group for Uncle Gnarley readers. I am pleased to welcome him to the blogosphere and say that I am very grateful to him for lending his expertise in such an important public policy area. - Des Sullivan
Phil Helwig is a retired Engineer and Hydropower Consultant with over five decades of experience - much of it right here in Newfoundland and Labrador. He has been a frequent writer to the Telegram on the North Spur stability problem as well as on other issues including power reliability and security.
This is Helwig's first contribution to the Uncle Gnarley Blog. It is a timely one, too. In recent weeks readers have seen posts regarding the Phase I Report of the Public Utilities Board (PUB). It dealt principally with the findings of the Liberty Group's investigation into the root causes of DARKNL. In late August Liberty filed its Report on Phase II of the PUB's mandate which includes consideration of security and reliability issues in the post-commissioning of Muskrat Falls. Phil Helwig has now distilled this Report and comments on the concerns of the Liberty Group for Uncle Gnarley readers. I am pleased to welcome him to the blogosphere and say that I am very grateful to him for lending his expertise in such an important public policy area. - Des Sullivan
COMMENTS ON: AUGUST 2016 LIBERTY REPORT ON SUPPLY
ADEQUACY AND RELIABILITY
Background:
Liberty notes that the in service date
of Muskrat Falls is delayed until 2020-21 a slippage of 3 years. This delay
extends the period of vulnerability of the Island System (IIS), since no new on
Island generation sources are planned. This is partly mitigated by the
reduction in the load growth forecast.
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| Phil Helwig, P.Eng. (Retired) |
Liberty divides their report into two
parts the first considering the IIS prior to in-service of Muskrat Fall and a
second part dealing with the interconnected Labrador-Island-Nova Scotia System.
Island System prior to infeed from Muskrat Falls:
1. Liberty
notes ongoing problems with Hydro’s thermal fleet, Holyrood (2x170, 1x150 MW),
Hardwoods C.T. (50 MW), S’ville C.T. (50MW). The new Holyrood C.T. (120 MW) is
presumably reliable.
2. The
situation is somewhat mitigated by the fact that the forecast load growth after
adjustments in 2016 reduce the load growth to 2019/2020 from 1.9% to 1.4% or
0.63% and 0.46% on an annual basis. (This is much less than the 2.0% per annum
in Nalcor original proposal!!)
3. Liberty
found Hydro’s load forecasting procedures as outdated and likely to
underestimate peaks compared to more modern approaches in use by most large
utilities in North America. I was
surprised that Hydro defined their estimated peak at the 50% probability level:
that is accepting a risk that 50% percent of the time the actual peak would be
larger than forecast. Liberty noted that the 90% point is more commonly used
implying that a forecast would be exceeded 10% of the time.
4. Liberty
identified several risks that need to be addressed in Hydro’s forecast, notably
a forecast risk. What is implied, but not stated in this last recommendation,
is a feeling that if Hydro’s forecast errors over one year 2015 to 2016 are significantly lower than previously expected; then
next year’s forecast could err on the
high side.
5. To
Liberty’s list of risk factors I would add a climate risk. As heating loads comprise
a significant portion of IIS, severe winter conditions would produce higher system
peaks requiring more resources; whereas, mild winters would produce lower peaks
and require fewer resources.
6. Liberty
suggests that new sources of supply for the IIS may be need before the winter
of 2020/2021 when Muskrat power becomes available. Additional generation and
other options for dealing with this shortfall in peak power are discussed at
some length in their report.
7. Liberty
notes that management of the challenges until 2020/21 is not limited to technical
issues but is equally dependent the ability of staff to manage contingency
situations. In this regard Liberty, note their concern about Hydro’s culture.
This issue is pursued later in Section V, page 81 on tolerance of UFLS
(under-frequency load shedding) and in Section VI, page 90 on Transition to
Operations (planning). Their comments on Hydro’s culture present a rather
narrow view of this matter in my opinion. I think there may be more profound
issues, notably: problems of political interference. I suspect there may still
be other issues but I am not familiar enough with Hydro’s current set up to be
a credible critic.
Labrador-Island Link
(LIL):
1. Liberty
provides a summary of the features of the HVDC system explaining its
performance, resilience and also vulnerabilities. The biggest risks are
associated with the mismatch between the size of the Labrador infeed and the
relatively small size of the Island System. Additionally, they note the
increased complexity of the LIL System and the demands this will put on Hydro
management. Essentially they are saying that the new scheme represents
promotion from the minor to the major leagues and will require a totally new
company (and operating culture).
2. Liberty
notes that the LIL has considerable resilience in that it can still meet most of
the forecast load with one pole out of service (monopole failure). A bipole
failure while less frequent is the main reliability concern as the IIS will
have difficulty with coping with this condition especially as the IIS matures. Nalcor
is counting on the supply of power from N.S. to mitigate the problem, but there
is no agreement about the modalities.
3. Some
questions about design are mentioned. The first involves the spacing between
cables. Liberty mention the spacing to be as little as 50 m. Earlier concepts
called for much wider spacing to reduce the risk of simultaneous cutting of
more than one cable by an iceberg scouring the sea bottom. The second of these
design decisions involves routing of the LIL T.L. over the Long Range Mountains
where icing conditions are particularly severe. An alternative route along the
Humber River and TCH would have avoided the high elevations of the Long Range
Mountains where icing problems are extreme. The current design is less
conservative but the reasons for the changes have not been explained in any of
the several presentations on Muskrat Falls that I have attended. Newfoundland
Power questioned the risk of failure of the ground(ing) wire due to icing and
the consequent risk of shorting out one or other poles. The concern arises
because the ground wire is lighter than the conductors but (may) support an ice
load equal to that of the conductors. Nalcor claim they have evaluated the
issue and concluded that the cost of a stronger wire is not justified.
4. Liberty
notes that limited data is available on cable failures based on experience of
power cables. It does not appear that any of the much more voluminous
information on subsea communication cable breaks was consulted.
5. Though
not mentioned explicitly, reliability problems will be less in early days but
become more of a challenge as the LIL matures.
6.
Liberty
is sceptical about Hydro’s assumptions about the time required to repair damages
to cables or OHL; noting, that failures are likely to occur during periods of
bad weather that complicate repair work and problems of access due to
remoteness of many portions of the T.L.
7. Liberty
reviewed the main issues concerning reliability of the converter station and
under-sea cables, OHL but notes the following issues that were not addressed:
· Tripping of some or all ac lines to
Muskrat Falls Converter Station
· Tripping of some or all ac lines to
Soldiers Pond Converter Station
· Delays in clearing faults near to
Muskrat Falls or Soldiers Pond
· Major faults, e.g., fire or extensive
insulation damage to 2 or more high inertia synchronous condensers, requiring
repair at times of high loading on the LIL
· Operator errors
· Major fires in the convertor stations.
They recommend that these issues be
evaluated in Hydro’s reliability studies. In my opinion several of these items
can be dealt with by proper design and quality training.
8. Liberty
is concerned about Hydro’s management of the Transition to Operations and
provides scopes and staffing requirements needed for this work, see Section VI:
Transition to Operations, page 90 in their report. The note and I quote: “Future reliability depends as much on such
people related improvements as much as it does on the billions of dollars of
investment.”
9. The point that most grabs my
attention is Liberty’s recommendation that Hydro, as a top priority, should
work out a deal with N.S. Power over (emergency) supply. This should have been
done long ago. Furthermore, Liberty mentions that we may have to pay for this
service - when N.S. is getting Muskrat Falls energy for free!!! This is
unacceptable in my opinion, should it ever come to pass.
10. Though not discussed by Liberty - the design
of the protection and control system is critical in maintaining system
stability when the system is stressed by major faults. The design should be
verified against all plausible perturbation/system faults. My guess is that the
loss of a power transformer that triggered the 2014 blackout may have been
omitted in Hydro’s analyses.
Signed: Phil
Helwig
_____________________________________________________________
Editor's Note:
Phil Helwig
has had a varied engineering career in both education (8 years) and in design
and technical management (44 years). Most of his formative experience was with
a small company in Newfoundland (ShawMont) which valued versatility, as a
result Phil was able to develop expertize that goes well beyond the skills set
normally associated with his formal area of competence, as a hydrotechnical
specialist. His main area of expertize is in the fields of hydropower and water
resources where he has been involoved in investigations, economic planning and
project optimization studies and detailed design. He has been responsible for
several innovations in Canadian practice: notably, the design of Cat Arm Hydel
unlined pressure tunnel (head = 386 m) and “bathtub overflow spillway” and
design of Hinds Lake Power Canal based on natural armouring (the first
application of this technology in hydro design world wide) and the design of
Paradise River double curvature arch dam only the third arch dam ever built in
Canada. More recently from his experience in South Asia
he has developed expertize in design of hydraulic structures to handle water
borne sediment. His latest interest is in the field of eco-hydraulics. In 2004
Phil formed his own company, Helwig Hydrotechnique Ltd. and has worked on four
continents in three languages. Technology
transfer is an integral part of all Phil Helwig’s assignments.