Transcript Challenge 1: Frequency deviations

Recent TSO report on changes because of
larger amounts of renewable enery
IEA Task 25, January 14, 2016
Edf – Clamart – Paris – France
Lennart Söder
Professor in Electric Power Systems, KTH
Background
• Sweden has currently around 15 TWh/year from wind
power, around 11% of production.
• 2014 the nuclear production was 62.2 TWh
• Prices are low and during autumn 2015 there cam a
decision to close the 4 oldest, out of 10, nuclear
reactors within some years (2014 these 4: 12,9 TWh)
• 2014: Net export of 15,6 TWh.
• Probably no new nuclear in Sweden
 wind+bio+solar is seriously discussed as ”the solution”
New TSO reports, required by government
”Adaption of the power system with a large
amount of renewable electricity”
http://www.svk.se/siteassets/om-oss/rapporter/anpassning-av-elsystemet-fornybar-elproduktion-delrapport.pdf
http://www.svk.se/siteassets/om-oss/rapporter/anpassning-av-elsystemet-med-en-stor-mangd-fornybar-elproduktion.pdf
Challenge 1: Frequency deviations - a
Wind power (Sweden)
Frequency deviations
HVDC capacity (Nordic syst)
•
•
•
Minutes per week when frequency is outside 50.0 ± 0.1 Hz
Goal is that this level should NOT be > 6000 minuts/year = 115 as weekly mean
value
2013: 11 428 minutes, 2014: 10 365 minutes.
Challenge 1: Frequency deviations - b
• Increased amount
of incidences when
frequency is outside
50 ± 0.1 Hz.
• Main challenge:
Market and
changes at hour
shift.
• Earlier ”margin
surplus” has
decreased
• Inreased wind
power may increase
this challenge.
More efficient handling
in control room
All deviations
At hour shift ± 10 min
Share at hour shift
Solution to Challenge 1: Frequency deviations
General answer:
More flexibility
Updated grid codes:
• Connection codes
• Operation codes
• Market codes
• ”Standards”, e.g.
min. 10 MW
• Change from hour
to, e.g. 10-15
minutes
• Balance Service
Provider: BSP-rules
• Harmonized
imbalance prices
Physical solutions:
• Household, industry
and prosumer
flexibility
• Rules for hydro power
• More bio-power
• Wind power control
• Energy storage
• Pumped storage
• Batteries
Other issues:
• TSO role
• Information
• Description of
current work
General conclusion
• No urgent needs
now
• Question is if
flexibility is
incentivized today?
Challenge 2: TSO Voltage control
• Sweden has long
transmission lines. The
transmission limits are set by
voltage stability.
• Current nuclear power
stations (10 GW, peak load
27 GW) are essential for
reactive power supply to keep
voltage.
• More wind power in north will
require more transmission
capacity.
Solution to Challenge 2: TSO Voltage control
• Synchronous condensers
• Operate hydro power stations
as synchronous condensers
(North)
• In South Sweden the ”probable
solution” is to use grid
Not considered (not so motivated)
components. ”This is not a
technical problem but increases • Use generators in closed nuclear
stations
the costs for grid operation”
• Use wind power. ”Renewable
• SVC and STATCOM: are seen
production is often connected at
lower voltage levels, which
as important solutions
implies that their voltage control
• New HVDC-VSC converts. (700
capability for the transmission
MW  ± 300 MVAr ≈ Nuc. Stat.
grid is nearly negligible”
Challenge 3: System inertia
• Large amount of wind
power  lower amounts
of synchronous
generators
• Disconnection of heat
pumps at 49,5 Hz for
more than 0,15 seconds
• New EU grid codes:
Lowest allowed frequency
49,0 Hz.
Frequency after outage of
Nuclear station O3, 1400 MW
Lowest frequency
49,36 Hz (all time low)
Solution to Challenge 3: System inertia
Physical solutions
• Increased amount of inertia by
running of existing synchronous
machines without generation. Today:
Practical solutions
3 hydro power stations (out of 150
large ones) can operate in this way. • Requirements for
• New synchronous condensers
Generators: E.g.
• Reduction of non-synchronous
”acivate within 2
production.
seconds”
• Reduction of largest possible outage • Demand Connection
• Faster response on frequency drop,
Code: React within
e.g. synthetic inertia from wind power
2 seconds.
or HVDC-VSC
Challenge 4: Peak capacity
• In Sweden we have a
”strategic reserve” of 2
GW (old oil-fired stations
+ DSM)
• TSO:s responsibility:
Tender before each winter
fot this strategic reserve
• Current challenge: Very
low prices + old plants 
close old plants, but the
only new plants are wind
+ solar.
• For the future: wind power
is cheaper than nuclear
• Peaks are rare!
• Wind power ”capacity
credit” = 11% of installed
capacity (>11% available
during 90% of the winter)
• 23 January 2015: Nordic
winter peak load, wind
power 5% of installed
capacity.
Solution to Challenge 4: Peak capacity
Physical solutions
• Not weather dependent
power production
• Demand side
management
Other issues in reports
• Current areas in Denmark
and Germany where
needed changes have
been identified.
Practical solutions
• ”The capacity of a unit
should have a value, not
only the energy”
• ”There are strong
incentives to, on a
national level, take
initiative to evaluate which
risk levels and costs the
Swedish society is
prepared to accept”
• Capacity payments