Oleksandra Dudurych Department of Electric Power Stations Institute of Power Engineering and Control Systems Lviv Polytechnic National University, Ukraine Reduced Inertia Response in Power Systems with High Penetration Systems with High Penetration Levels of Wind Energy Supervisor: Dr Michael Conlon School of Electrical and Electronic Engineering Dublin Institute of Technology, Ireland
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Reduced Inertia Response in Power Systems with High ... 02...Reduced Inertia Response in Power ... Inertia of the power system is proportional to the ... Frequency stability in the
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Oleksandra DudurychDepartment of Electric Power Stations
Institute of Power Engineering and Control Systems
Lviv Polytechnic National University, Ukraine
Reduced Inertia Response in Power
Systems with High Penetration Systems with High Penetration
Levels of Wind Energy
Supervisor:
Dr Michael ConlonSchool of Electrical and Electronic Engineering
Dublin Institute of Technology, Ireland
Overview
� Inertia Response and RoCoF
� What is Inertia?
� Why is Inertia important?
� The maths behind Inertia
� WTGs Concepts
� Wind Energy in Ireland� Wind Energy in Ireland
� Study Model using PowerFactory
� Simulation
� Results
� Conclusions
� References
What is Inertia?
� Inertia can be seen as the “resistance to change”
� Inertia of the power system is proportional to the
amount of rotating masses in the system
� It prevents the grid frequency suddenly changing
and results from synchronous generatorsand results from synchronous generators
� Inertia determines the rate of change of frequency
(RoCoF) following a load event
Why is Inertia Important? (1)
� The mechanical and electrical energy must be
balanced during steady state mode
� The balance between the supply and demand power
must be maintained
� The larger the system inertia, the less is the rate of
change of frequency following a power imbalancechange of frequency following a power imbalance
� When a mismatch is between the supply and
demand in the system, the rotors of the connected
generators will release or absorb kinetic energy and
as a result, the rotational speed and frequency will
change
Why is Inertia Important? (2)
� This is known as Inertia Response
� Inertia shows the speed of change of frequency
� This is important because many distribution
generators have their anti-islanding protection
based on RoCoF relay
� If RoCoF is high and there are a lot of distribution� If RoCoF is high and there are a lot of distribution
generators in such system, they will trip and system
will collapse
� Grid Code RoCoF standard is 0.5 Hz per second
The maths behind Inertia
Inertia and Wind Turbine Generators
� The traditional synchronous generators have certain
qualities which are very essential in controlling the
grid frequency
� WTGs currently do not participate in frequency
regulation. They do not increase or decrease their
power output when the frequency deviates from itspower output when the frequency deviates from its
nominal value
� Frequency stability in the power grid is essential for
maintaining security of the supply, this inadequacy
of the WTGs may pose a limit to the level of
penetration of these technologies into the existing
system
WTGs Concepts (1)
� Fixed speed
WTGs – are directly
connected to the
grid, there would notgrid, there would not
be much change in
the inertial and droop
responseWT with IG
WT with DFIG
� Variable speed
WTGs – the power
electronics interface
between the generator
WTGs Concepts (2)
WT with DFIG
WT with fully rated convertor SG
between the generator
and grid results in an
electrical decoupling,
due to which the inertial
and droop capabilities
will be missing
Wind Energy in Ireland (1)
� In Ireland currently all types WTGs are used, mainly
DFIGs
�Changes in transmission System required to facilitate
40% of electricity from renewable sources by 2020
�One of the range of challenges is reduction of inertia
in system with increasing windin system with increasing wind
�Higher values are observed under conditions of high