The Massive InteGRATion of power Electronic devices - Enabling the energy transition by providing solutions for the technological challenges ...
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The Massive InteGRATion of power Electronic devices Enabling the energy transition by providing solutions for the technological challenges
The MIGRATE project was funded by
the Horizon 2020 programme for research
and innovation. Coordinated by TenneT,
the project gathered 12 Transmission System
operators together with 13 other partners
bringing research and innovation expertise
as well as industrial background.
Key Figures
2 3Renewable energies challenge today’s power system This change raises the following questions:
A cleaner energy system is one of the key priori- In this energy transition, renewable electricity — ⸺ The inertia in the power
ties of the European Union for the next years and mainly generated from wind and solar resources system will decrease conse- ⸺ How can the protection
even decades. Among other objectives, the Euro- — has a major role to play. But its massive integ- quently leading to a ‘faster’ schemes — i.e. the de- ⸺ What is the impact of
pean Commission targets at least a 32% share of ration into our power system is a real challenge system response. Will the PE tection and isolation of massively integrated PE
renewable energy consumption by 2030. that can be summarized in two questions: converter controls — initially faults — be adapted to units on power quality
designed for ‘slow’ conven- the new power system (voltage, frequency,
tional power systems — be characteristics, e.g. very waveform), and how can
able to cope with this? low fault currents? this impact be mitigated?
The MIGRATE project explored these different questions by:
⸺ Investigating the different dimensions ⸺ From a future perspective: exploring how a
of power system stability, how it can be power system with 100% power electronics
measured, monitored and forecasted; could be operated, and what would be a
From its origin, our power system has been desi- transitional pathway to that point;
gned around large rotating machines — synchro- ⸺ From today’s perspective: assessing the
nous machines — that generate electricity from maximum share of power electronics in ⸺ Developing and testing new tools to ensure
conventional energy sources and feed it into our We, in TenneT, already a power system before mitigation mea- power system protection, automated cont-
electrical network. Electricity supply is like a ba- identified new challenges of sures are required to maintain system rol and power quality in power systems
lancing game in which all players rely on the con- a converter dominated power stability, and how it should be mitigated; with high PE penetration.
ventional system behavior constituted by syn- system in the past within our off-
chronous generators. The massive employment
of renewable energy sources (RES) acts like a
shore grid connection systems in
game changer and leads to rethinking the way the German North Sea. Hence, we
we manage network stability. were aware that further research
and investigations are necessary
in order to be prepared to operate Inclusion
The inertia of today’s power system contributes
every day to maintain the system’s stability.
a power system with increasing
share of power electronics and
Stability of the power system
The massive deployment of renewable electri-
city sources interfaced to the grid by power less inertia.
converters displaces synchronous generation Minimum acceptable stability level
and therefore reduces the total system inertia Hannes Munzel
and requires innovative solutions in the way MIGRATE Project Coordinator Improvement
of system
power system security of supply is managed. Transit zone
stability within
Technology leap
System stability is addressed within the existing System stability is addressed with
the existing framework: controllers framework breakthrough methodologies and
and grid codes controllers with modified grid codes
Indeed, RES like photovoltaics or wind turbines RES share increases significantly in a power system,
are connected to the network via power electro- the behavior of the PE converters will dominate the
nic (PE) interfaces. Seen from the network, there overall power system characteristics. In addition,
Power electronics penetration L3% L1% L2% 100%
is no synchronous generator with its conventional other PE devices are spreading on the network,
behavior anymore but a power electronic conver- such as high-voltage direct-current (HVDC) systems,
ter whose behavior largely depends on the algo- flexible AC transmission systems (FACTS), and PE Illustration
Illustration ofofthe
themain
mainconcept
conceptof of
thethe MIGRATE
MIGRATE project.
project. The The abscissa
abscissa represents
represents the PEthe PE penetration
penetration where
where L1 and L1 and
L2 are asymptotes where severe stability problems could be met within the existing framework. The ordinate axis
rithms embedded in its control circuitry. When the connected loads from industrial sites. L2 are asymptotes where severe stability problems could be met within the existing framework. The ordinate axis
represents a generic stability index
represents a generic stability index.
4 5Inertia is a local phenomenon,
to be dealt with through locational strategies
⸺ Data gathered by synchronized measurement technologies shows
that inertia is not a system-wide generic feature, but rather a series
of local area characteristics. Power systems behave as dispersed,
interconnected centers of inertia.
There is a technically feasible pathway towards stable 100% PE networks
⸺ Consequently, mitigating low inertia requires locational measures. A WAMPAC
⸺ Analyses performed on the simplified Irish ⸺ In the perspective of a full PE-based power system (Wide Area Monitoring, Protection, and Control) was tested in Iceland,
network show that a conventional power network (at least at some points in time), combining real time monitoring and fast frequency response services enabled by
system can cope with up to approx. 65% simulations on the test Irish system model controls on existing load and generation resources of the energy system (hydro
instant penetration of power electronics showed that a 100% PE network can be generation and industrial loads). This world-first WAMPAC deployment revealed
based generation units, while maintaining operated safely when 30% of PE-interfaced very successful in improving network stability, with positive perspectives in
network stability. devices are equipped with grid forming terms of cost savings and new ancillary services.
controls. Real small-scale tests successfully
⸺ To that end, some adjustments are required showed the interoperability of several grid
on the existing conventional control loops forming controls developed independently.
of power electronic based generation units
(e.g. wind turbine power converters). These ⸺ A first economic assessment of deploying
controls are termed “grid following” controls grid forming controls, compared to synchro-
as they measure the system frequency and nous condensers (a conventional stability
provide active/reactive power at that fre- management strategy based on adding New protection schemes are required… and available
quency by injecting currents into the ener- physical inertia to the system) points to-
gized power grid, i.e. behaving like current wards the economic competitiveness of
sources. the grid forming approach. ⸺ Some protection schemes are seriously impacted by a high penetration of
power electronics in the system, and particularly the distance protection function.
⸺ Introducing in complement a proportion of ⸺ Considering adjustments in present protec- New tools, a clear definition of the required response of power electronics during
new grid forming controls in the PE-based tion philosophies and the introduction of short-circuits and a more cross-disciplinary approach with the power electronics
generation units, i.e. controls that no longer new protection technologies adapted to field are required to prepare the future.
behave as current sources but rather as vol- this new scenario together with the definiti-
tage sources and synchronize with others, on of rules for the behavior of PE based ge- ⸺ New protection algorithms were developed and successfully tested to operate
has shown to ensure system stability with up nerators during short-circuits would allow under massive PE penetration: they include fault detection, faulted phase
to 90% of PE penetration (defined on MVA a safe integration of renewable energies selection and underfrequency load shedding scheme. Three patents were
base) on the synthetic Great Britain test maintaining present levels of security submitted, one being under further feasibility analysis for integration into the
system. of supply. commercial offer of the equipment manufacturer partner.
MIGRATE contribution towards more renewable energy sources into the grid
Power quality
2016 level ⸺ Simulation performed according to a probabilistic approach to harmonic
New Power Quality mitigation measures propagation, showed that an increased PE penetration (from 60 to 90%)
leads to a tripling of frequency variations and an increase of the total
harmonics distortion (THD) above the 3% in 5% of substations.
New protection algorithms
Control Design ⸺ Mitigating frequency variations could be performed by wind turbines providing
Real-time monitoring & forecasting of KPIs
Wide-Area-Controls
framework a new type of balancing services, through adjusted controls allowing to store and
conditions
then release some of their kinetic energy.
Extended stability boundaries
New Grid
Forming controls ⸺ While PE devices introduce harmonic distortion into the grid, they can also be part
Mix of grid following
of the solution. New controls can be implemented to minimise the device emissions
Improved grid following controls
and grid formin controls and even to introduce additional damping to the system, contributing to an overall
reduction in harmonic levels. Mitigating harmonic distortions requires an economic
30% 65% 70% 90% 100% trade-off between a decentralised approach (controls and filters at PE device level)
Power Electronics Penetration level
and a centralised approach (filters on the network).
6 7Stability Issues Rethinking power stability assess-
Identified by TSOs
ment under high PE penetration
Rotor Angle Frequency Voltage The first step in MIGRATE was to investigate
Stability Stability Stability Others the main instability phenomena triggered
by high PE penetration in order to propose Combining grid following and grid forming controls allows to push
(1) Introduc- (3) Decrease (5) Loss of (10) PE
updated stability measurement methods further the stability limit — up to a theoretical 100%
tion of new of inertia devices in the Controller and tools. Eleven critical stability issues were
power oscil- context of interaction identified and prioritized with the help of The approach presented in the previous page In order to address this 100% PE system per-
lations and/or fault ride- with each
reduced (4) Missing or through other and European TSOs, the four major ones being focused on increasing the PE penetration in spective, MIGRATE developed a new type of
damping of wrong partici- capability passive AC
existing power pation of PE components frequency stability, rotor angle stability, today’s power systems by modifying the existing controls, called grid forming (in opposition to
oscillations connected
generators (6) Voltage dip short-term voltage stability and sub-syn- controls in the grid. In complement, MIGRATE also grid following), as they no longer behave as a
and loads in induced fre- (11) chronous controller interactions. considered the perspective of a 100% PE system current source — but rather as voltage sources
(2) Reduction frequency quency dip Resonances
of transient containment due to cables in order to investigate whether and how such a and synchronize with others. The grid forming
stability and PE Based on this knowledge, a methodology system could be operated safely. And possibly, concept and developments are detailed
margins (7) Lack of
reactive power was proposed to evaluate the distance to whether those two complementary approaches in the next pages.
stability, i.e. the tendency of the system were compatible at some point.
(8) Excess of
reactive power to move from a stable condition to the stability limit (i.e. the
threshold defined by the operator for a stability indicator such
(9) Altered as rate of change of frequency (RoCoF), frequency nadir or critical
static and dy-
namic voltage clearing time). KPIs were therefore defined, allowing a mapping
dependency of one or several system variables onto the actual value of a
of loads
stability indicator.
In complement, a PE penetration forecast tool was developed
for accurate forecasts up to 3 hours ahead, based on optimized
artificial intelligence models (Artificial Neural Network), as well
as a related prototype visualization tool for the control room as
guidance.
The analysis performed on a synthetic Great Britain
power system model showed that a combination of
modified grid following controls and new grid forming
controls on power electronic interfaced RES allow the
Adjusting existing controls allows to reach approx. 65% PE penetration stable operation under up to 90% share of PE.
The next objective was to test whether and how ⸺ Fast active power injection (FAPI) control-
existing controls of PE connected generators, lers implemented on type-4 wind genera-
storage devices or demand responsive loads tors allow to keep the maximum frequency
could be adjusted in order to allow for an increa- deviation (Nadir) within the threshold de- Resulting controls’ interactions can be managed
sed penetration of power electronics. By existing fined in current grid code requirement.
controls are meant grid following controls, i.e. Having a number of PE converters located ⸺ A method to design, evaluate and validate
controls that provide active and reactive power ⸺ Supplementary damping control (SDC) on in the close vicinity of each other can lead to different mitigation solutions to tackle SSCI,
by injecting currents into the energized power wind generators help to reduce the first adverse interactions between these PE de-
grid (current source behavior). swing’s maximum rotor angle deviations vices (in particular series compensated sys- ⸺ A new approach based on artificial intelli-
and to successfully damp out electrome- tems), referred to as sub-synchronous con- gence to manage SSCI risk during real-time
A set of adjusted-grid following controls were chanical oscillations. troller Interactions (SSCI). A methodology operation.
therefore built upon and evaluated based on IEC was therefore proposed to investigate such
standard models and hardware in the loop tes- ⸺ Some forms of sub-synchronous controller interactions. It includes:
ting. Results show that those modified controls interactions were successfully mitigated by This first step to manage SCCI in the operational
allowed to reach approx. 65% of PE penetration tuning of wind generators’ converter con- ⸺ Recommendations for the tuning of time frame is promising, and further research is
in the studied system while maintaining stability. trollers as well as by introducing auxiliary PE controls via parametric sensitivity required to complement and test the robustness
In particular: controllers in the converters. analysis or optimization, of this approach.
8 9A paradigm shift for ancillary services
Grid forming controls could then be used to provide both existing system
services like frequency control, and new services that exploit the flexibility
and fast actuation of power converters, such as electrical inertia or fast
frequency response with limited storage.
The algorithmic developments, simulations The simulations performed on the Irish sys- MIGRATE provided a proof of concept on the provision of such ancillary services,
and laboratory tests performed in MIGRATE tem showed that operating a stable 100% complemented by a method to optimize the location and parameters of power
showed that operating a system with 100% PE network requires that approximately converters providing grid support. Indeed, location matters: results show that
PE is indeed possible. A necessary condition 30% of converters are equipped with grid the efficiency of the virtual and electrical inertia services provided depends
is that some converters are equipped with forming controls. not only on their amount but also on their location in the grid. A real shift in
grid forming controls, as defined below. paradigm for the ancillary service markets, which do not capture this locational
dimension so far.
Different grid forming controls
can be interoperable
A definition of grid forming
During the project, three types of grid- Filtered frequency droop Dispatchable Virtual oscillator Matching control
Grid forming controls shall forming controls were developed:
ω
⸺ behave as a voltage source. ⸺ Droop control, which adjusts voltage idc θ, ω is
frequency with active power. It syn-
m Тm +
ω* l g + Rl L l il
Тc
Lθ v
Тs Тs
−
⸺ be synchronized with other chronizes the sources on transmission
vde Cde Gdc
+ M
ωsync m θ − v Тʃ iʃ
voltage source, if any. grid and provides in addition some
− − vʃ +
inherent frequency control. P1 P2
P
synchronous machine matching
⸺ behave properly in islanded
mode (do not rely on direct ⸺ Dispatchable virtual oscillator, which
frequency measurement). uses the oscillator self-synchronization
property to synchronize on the grid.
⸺ take care of overcurrent
limitation (be a voltage ⸺ Matching control that matches the
source as much as possible). equations of the synchronous machine
to the equations of an inverter with a
⸺ be compatible with all presently DC source.
connected devices, including
synchronous machines and All three algorithms developed were
other grid following controlled tested with real hardware at small scale
units in the system. and turned out to be interoperable.
The algorithms are released open source. Grid forming could compete
with synchronous condensers
Today, several TSOs chose to invest in synchronous condensers
to provide electrical inertia and voltage strength to their system
and support network stability. The large-scale deployment of
grid forming controls could constitute a viable alternative to
Converters’ vulnerability to overcurrent can be dealt with that strategy.
Unlike synchronous generators, power conver- vent the current from going over a defined limit, MIGRATE developed use cases for France and Germany to
ters can only cope with small overcurrent (of a while maintaining the voltage source behavior compare the costs of those two alternative strategies under
few percent of their own rated current). In order (required in grid forming controls – see definition scenarios of high PE penetration. Results show that the overall
to protect their semiconductors from the dama- above) during the fault. It is based on the tuned costs (CAPEX and OPEX) are of the same order of magnitude,
ge caused by over-currents, a current limitation combination of two conventional current limita- even leaving aside the potential value of additional ancillary
strategy was developed and integrated in the tion techniques that are virtual impedance and services that grid forming controls could provide (see above).
converter control algorithm. This allows to pre- current saturation.
10 11“Location matters”:
Inertia has a local dimension
that can be monitored using
synchronized measurement
technologies
Regional inertia issues can be addressed by fast control
MIGRATE investigated how the commercially available synchronized that is sensitive to disturbance location.
measurement technologies could be better integrated to improve A world-first live wide area control demonstration in Iceland proves
the knowledge, monitoring and forecast of stability indicators
in low-inertia and PE-intensive systems. the capability to use existing demand and generation for fast, loca-
tional, proportionate response to mitigate low inertia problems.
Measurements using synchrophasor technolo- A set of tools to monitor this area inertia KPI
gies such as phasor measurement units (PMUs) were developed and tested using network data The icelandic network (see illustration
show that a power system does not behave like from the wider consortium of TSOs. The TSOs on the right) features distant centers of
a single center of inertia but rather like dispersed, data represented vastly different networks with inertia that are separated by long trans-
interconnected centers of inertia. different behaviors and characteristics, allowing mission corridors, leading to serious
to extensively test and validate the tools. angle stability issues. A pilot WAMPAC
MIGRATE developed the concept of Effective system (Wide Area Monitoring, Protec-
Area Inertia as a key performance indicator that Complementary tools were also developed tion, and Control) was deployed on the
reflects the regional dimension of inertia, by cap- to monitor System Strength and Short Circuit Icelandic grid in order to mitigate in-
turing the relationship between the power imba- Capacity: Short Circuit Capacity relates to the stability events through services provi-
lance and the rate of change of frequency (RoCoF) system performance during a fault, while System ded by existing equipment connected
of a given area. Such KPI can be processed thanks Strength refers to non-fault, near-nominal voltage at generation and demand side. Those
to PMU data and directly used to determine area- characteristics. As the system behavior changes services, called fast-acting grid control,
based frequency response requirements or to due to the increase of PE, these two characte- are enabled by PMU data combined 220kV
132kV
design fast frequency control schemes ristics are becoming increasingly distinct and with control measures that can ramp- 66kV
(see next page). different. The tools were validated following up and down some generation resour- 30kV
the same approach. ces (hydro) or step-up and down some
loads (smelter and factory loads).
Forecasting tools for these indicators were
also developed using machine learning (neural
networks) and tested on both model-based The control methodology developed can identify connections where parts of the system
Total Area Generation 8082.68 MW
simulations and measurement-based results. the area where disturbance occurs, and its severi- undergo low inertia and transmission
Total Area Load 2457.37 MW ty based on the inertia estimates and the rate of boundary constraints.
Percentage PE Gen 22.71 %
Percentage PE to Load 74.68 %
change of frequency (RoCoF). Once the distur-
Area Inertia 20088 MWA S bance location is quickly and reliably detected, The approach is also economically viable as sig-
Total Area Generation 6394.48 MW
Total Area Load 8873.86 MW
the available response within each area can be nificant cost savings can be reached by harnessing
Percentage PE Gen 32.57 % triggered in order to improve frequency and angle the capabilities of existing connected load and
Percentage PE to Load 23.47 %
Area Inertia 47628 MWA S
stability. Pilot tests showed that response trig- generation when compared to deploying dedica-
gers could be delivered in less than 0.5 seconds, ted devices such as battery storage to provide
Total Area Generation 6956.66 MW Total Area Generation 3334.47 MW and discrete response fully activated in less than fast response services.
Total Area Load 8743.97 MW Total Area Load 3396.79 MW
Percentage PE Gen 1.83 % Percentage PE Gen 22.22 % 1 second. Shorter response time could be achie-
Percentage PE to Load 1.45 % Percentage PE to Load 21.81 % ved if needed with further work. In addition, it creates new opportunities for any
Area Inertia 9090 MWA S
Area Inertia 57510 MWA S grid user with significant response capability to
Total Area Generation 6224.22 MW Wide-Area-Control schemes clearly proved to participate to ancillary service markets, with
Total Area Load 7216.24 MW
Percentage PE Gen 10.58 %
be successful in the Icelandic grid to improve services that combine angle stability, frequency
Percentage PE to Load 9.13 % system stability. This experience is valuable for stability, balancing and islanding.
Area Inertia 19440 MWA S
Forecasting tool other low-inertia systems and for larger inter-
13Protection schemes are crucial to detect and isolate disturbances on the network, whose
propagation would otherwise trigger blackouts of considerable areas of the power system.
Present protection schemes have been developed considering that synchronous generators
were the main source of short-circuit current. Whereas synchronous generators’ behavior is MIGRATE developed and patented innovative short circuit
well-known and predictable, PE-based generators respond differently during short circuits,
and their behavior can differ from one manufacturer to another.
protection and system integrity protection schemes to cope with
high PE levels — one of them is under industrialization process.
In MIGRATE, experts in power system protection and in power electronics worked jointly
to assess the impact of a massive PE penetration on protection schemes and explored
how the related equipment and algorithms should be modified in order to cope with
higher shares of power electronics in the grid.
Based on the previous findings, MIGRATE de- The first three algorithms were tested into
veloped and tested several protection algorithms real commercial or pre-commercial protec-
to overcome the barriers identified with regards tion relay platforms, with conventional ge-
Distance protection is the most severely impacted to protection scheme performances under high nerators and with three types of PE-
by massive power electronics PE penetration scenarios. Developments include: connected generators (photovoltaic, full
converter wind turbine and doubly fed in-
The studies conducted allowed to identify the main control parameters of PE converters that ⸺ A faulted phase selector that improves the duction generation) on three different lines
impact protection systems, and which protection schemes and functions were affected during overall behavior of present distance protec- of different lengths. Test results were con-
short circuits fed by PE-based generators. tions. It uses an adaptive time window that clusive with promising perspectives.
avoids the issues of present algorithms
concerning the different response times and The results show that, with the adaptations
Two types of protections were tested: Results show that: transition periods of PE-based generator proposed by MIGRATE, the impact of the
controls. A European patent has been sub- penetration of PE-based generators in pre-
1 Short circuit protection relays, which mea-
sure and act locally in a single element (a
line, transformer, generator) within tenths
⸺ For short circuit protection, distance
protection is the most affected functi-
on, with mal-operation at fault detec-
mitted for this algorithm.
⸺ A fault identification algorithm that over-
sent distance protection functions can be
mitigated.
of milliseconds. Three key protection func- tor, fault phase detector and directio- comes the problems of nuisance tripping The algorithms were then tested against
tions were tested: differential protection, nality levels. Also, the strong influence of distance protections. The phase selection their industrial feasibility (CPU loads and
distance protection and ground directio- of PE converters control behaviors on is determined by assessing fault detection, memory needs), and the undervoltage al-
nal overcurrent protection. Hardware in these functions requires to fully incor- impedance computation and directionality gorithm and the improved faulted phase
the loop testing was performed on real de- porate expertise on power electronics (zone determination). It is under patenting selector algorithm revealed strong potenti-
vices from four different manufacturers. in protection studies (models and process. al for industrialization. The undervoltage
tools, academic curricula). algorithm and faulted phase selector will
⸺ An undervoltage algorithm, i.e. a fault de- be potentially included in a new generation
2 System Integrity Protection Schemes (SIPS)
which monitors stability at system level via
measurements in different points of the
⸺ The tested System Integrity Protection
Schemes are not fully reliable under
high PE penetration, and require adap-
tection algorithm that uses an adaptive un-
dervoltage criteria to detect faulty phases.
of relays that will be released during the
next years.
network, in hundreds of milliseconds. tations to cope with higher shares of PE. ⸺ An algorithm for underfrequency load
Three SIPS applications were modeled and shedding schemes (UFLS), combining a
tested under different scenarios of PE pe- ⸺ It is important to clearly define one-stage scheme for systems with known
netration, namely undervoltage load shed- requirements for the behavior of power constant of inertia, and a two-stage scheme
ding, underfrequency load shedding and electronics based generators during for systems with unknown inertia constant.
power swing tripping. short-circuits.
14 15The future challenge of power quality
The proliferation of power electronics but also for the overall power system: ⸺ The importance of power quality among European TSOs
devices in the power system triggers an higher harmonic distortion combined with is increasing and more resources are allocated to its management.
increase in harmonics, i.e. voltages or higher frequency deviations leads to in-
currents whose frequencies are multiples creased power losses on the network, can ⸺ The most relevant power quality characteristic considered
of the network’s fundamental frequency, induce errors in the measurement devices in Europe is harmonics.
which constitute a deterioration of the of the grid, or even negatively contribute
power quality. This can be an issue for to certain network events (short circuits, ⸺ Most of the TSOs who deal with power quality have respective
some sensitive industrial consumers, loss of the supply or load, etc.). procedures available for defining/setting limits for new customer
connections and for compliance verification.
⸺ However, different methodologies are implemented by European TSOs
in order to determine respective planning and compatibility levels in
the system and for customers.
A probabilistic approach to assess and mitigate harmonics propagation
Tackling harmonics implies to assess how they The methodology was implemented on a test
propagate over the network in order to apply mi- network to assess the impact of an increasing
tigation measures accordingly: a real challenge, penetration of power electronics on power quality.
as there are numerous potential sources of har- Results show that increasing the PE share from
monics, which generate them in a random man- 60% to 90% leads to:
ner with variable propagation patterns.
⸺ A tripling in frequency variations,
A probabilistic approach was therefore developed
to assess harmonics propagation considering the ⸺ An increase in total harmonic distortion
uncertainties in harmonic sources’ location and above the widely accepted 3% limit
rate of harmonic generation. This methodology in 5% of the substations.
allows to detect the most vulnerable areas in the
network, identify harmonic propagation patterns, Wind farms should enter
and assess the impact of an increasing presence the ancillary services markets
of PE devices on these areas. Then, an optimiza-
tion-based approach allows to design the most MIGRATE also studied how to better maintain acceptable po-
cost-effective mitigation strategy. wer quality levels by reducing frequency variations caused by
a high penetration of intermittent renewable energy sources.
Ireland Ireland Ireland
Frequency variations increase as the RES penetration increases
7th Harmonic 7th Harmonic 7th Harmonic
and trigger a growing demand in energy balancing services in
(0% wind) (30% wind) (60% wind)
order to maintain frequency stability. Such a demand cannot
be met by the remaining synchronous generators that become
4D visualization of harmonics propagation fewer and fewer in a high-RES scenario.
to support network monitoring and control
A mitigation method was therefore developed, enabling wind
The ODIN-PQ tool was developed to provide a 4D graphical turbines to provide such balancing services. The method uses
representation of harmonics propagation, enabling a rapid vi- wind speed forecast and system frequency forecast as inputs,
sual check of the power quality situation on the grid. The tool and it adjusts controls to allow wind turbines to use the kinetic
uses either measurement results or simulations as inputs and energy stored in their rotating masses. The related algorithm
provides video-style (time-lapse) animations on historic data is currently investigated for patent eligibility.
for control and analysis purposes, or on simulated data for
the study of future scenarios. This paves the way to a real participation of wind generation
to ancillary service markets, but also opens regulatory per-
The tool can be freely downloaded at TU Delft Repository. spectives on new requirements in network codes.
16 17to create new or modify the existing balancing service,
focusing on frequency variations mitigation using wind turbines
in order to significantly reduce the primary and secondary regulation
needs.
to consider requiring grid forming control functionality
in the specification of future PE projects.
to prepare for more detailed modeling of power systems and PE units
in order to maintain TSO ability to analyze future power system stability
under high PE penetration, in particular in terms of SSCI and PQ.
to encourage TSOs to make use of their synchro-phasor data. There is a critical need to continue the in-depth analysis how the application of AI techniques in
to observe the dynamic characteristics as inertia and system strength issues impact grid planning and operation can facilitate the massive PE integration.
stability among other stability KPIs.
to further explore the possibilities how PE penetration can be monitored using
to consider inertia as clusters connected by network corridors, real-time online measurements of typically available power system signals.
and not as a single system-wide inertia. Angle stability is also related
to regional inertia, and islanding can occur in low inertia regions even
in larger high-inertia systems or interconnections. to open the grid code for grid forming requirement from inverters.
Main guidelines are presently within MIGRATE. Grid forming technology is the
only enabler for a 100% PE grid, and it already showed positive impact on grid
to encourage TSOs to explore possibilities of Wide-Area-Controls within their grids. with synchronous machines.
They are a very valuable and economical approach for locational fast frequency
control, enabling network stability improvements together with frequency
management. to review protection philosophy and criteria in order to ensure a secure transition
towards a power system with high penetration of power electronics.
to differentiate system strength (or “stiffness”) from short circuit level.
The historic assumption that they were approximately the same is to define clear requirements for the behavior of power electronics during balanced
no longer valid. and unbalanced faults and, ideally, these requirements should be harmonized at
European level.
to be aware of system strength issues which can lead to higher frequency oscillation
phenomena, typical 4–12Hz voltage control oscillations. Fast oscillatory instability to implement new protection technologies such as adapted distance protection
detection is available that can be used to detect, alarm and potentially mitigate algorithms, time-domain protection functions and WAMPAC systems can facilitate
the rapid onset of these oscillations. the transition, however careful assessment of these technologies and their appli-
cability to specific power systems must be made, as their behavior will be greatly
affected by the controls of power electronics.
to use probabilistic approach to harmonics mitigation since taking
into account future scenarios enables more future-proof solutions.
to review the tools commonly employed by protection engineers in their studies,
in order to adapt them to this new scenario in which power electronics expertise
to use optimization-based approaches to design the most cost-effective must be included.
mitigation strategies for harmonics.
to use new wind turbines control algorithm, which significantly reduces
the frequency variations, is easy to implement in (existing) wind turbines
and only minimally reduces total energy output.
18 19MIGRATE is the largest TSO project funded by the European
Commission under the framework of Horizon2020.
Thanks to all who worked on the project tasks during the past four years.
It was a real pleasure to collaborate with such dedicated people from
different countries, with different backgrounds and different cultures.
However, all of the involved colleagues had and have the same aim.
Hopefully, the efforts and results of MIGRATE will make the energy system
of the future more reliable and sustainable.
On behalf of TenneT
Hannes Munzel (Coordinator)
More information and public deliverables can be found here:
www.h2020-
www.h2020
www.h2020-migrate.eu
-migrate.eu
TenneT TSO GmbH Nothing from this edition may be reproduced without the express permission of
Bernecker Straße 70 TenneT TSO GmbH or published in any other way. No rights can be derived from
95448 Bayreuth the contents of this document. The information, documentation and figures in this
Germany brochure are written by the MIGRATE project consortium under EC grant agreement
No. 691800 and do not necessarily reflect the views of the European Commission.
Phone + 49 (0)921 50740-0 The European Commission is not liable for any use that may be made of the
Fax + 49 (0)921 50740-4095 information contained herein.
E-Mail info@tennet.eu
www.tennet.eu
19109
This project has received funding from the European Union’s Horizon 2020
research and innovation programme under grant agreement No 691800.You can also read
