Acknowledgements Control of Low-Inertia Power Systems: Naive & Foundational Approaches ! ! ! ! INCITE Seminar @ Universitat Polit` ecnica de Catalunya Florian D¨ orfler B.K. Poolla C. Arghir T. Jouini P. L¨ utolf D. Groß S. Bolognani S. Curi M. Colombino 2 / 56 What do we see here? Frequency of West Berlin when re-connecting to Europe Source: Energie-Museum Berlin December 7, 1994 Hz Hz BEWAG UCTE *10 sec BEWAG UCTE *10 sec before re-connection: islanded operation based on batteries & single boiler afterwards connected to European grid based on synchronous generation 3 / 56 4 / 56
Essentially, the pre/post West Berlin curves date back to. . . Operation centered around bulk synchronous generation 50.02 50.02 f [Hz] f [Hz] Primary Control Tertiary Control 50.01 50.01 50.00 50.00 f - Setpoint 49.99 49.99 49.98 49.98 Secondary Control 49.97 49.97 49.96 49.96 PP - Outage Oscillation/Control 49.95 49.95 PS Oscillation 49.94 49.94 49.93 49.93 Fact: all of AC power systems built around synchronous machines ! Mechanical Inertia 49.92 49.92 49.91 49.91 θ , ω At the heart of it is the generator swing equation : 49.90 49.90 τ m 49.89 49.89 generation demand M d dt ω ( t ) = P generation ( t ) − P demand ( t ) τ 49.88 49.88 16:45:00 16:45:00 16:50:00 16:50:00 16:55:00 16:55:00 17:00:00 17:00:00 17:05:00 17:05:00 17:10:00 17:10:00 17:15:00 17:15:00 8. Dezember 2004 8. Dezember 2004 Frequency Mettlen, Switzerland Frequency Athens change of kinetic energy = instantaneous power balance M Source: W. Sattinger, Swissgrid 5 / 56 6 / 56 Renewable/distributed/non-rotational generation on the rise The foundation of today’s power system synchronous generator new workhorse scaling Synchronous machines with rotational inertia M d dt ω ≈ P generation − P demand new primary sources location & distributed implementation Today’s grid operation heavily relies on 1 robust stabilization of frequency and voltage by generator controls 2 self-synchronization of machines through the grid 2 M ω 2 as safeguard against disturbances 3 kinetic energy 1 focus today on non-rotational generation We are replacing this solid foundation with . . . 7 / 56 8 / 56
Tomorrow’s clean and sustainable power system The concerns are not hypothetical: South Australia event Non-synchronous generation connected via power electronics UPDATE REPORT ! BLACK SYSTEM EVENT IN SOUTH AUSTRALIA ON As of today, power electronic converters 28 SEPTEMBER 2016 1 lack robust control for voltage and frequency AN UPDATE TO THE PRELIMINARY OPERATING INCIDENT REPORT FOR THE NATIONAL ELECTRICITY MARKET. DATA ANALYSIS AS AT 5.00 PM TUESDAY 11 OCTOBER 2016. 2 do not inherently synchronize through the grid 3 provide almost no energy storage my conclusion from official report: blue low-inertia area 5 was not resilient; conventional system would have survived What could possibly go wrong ? 9 / 56 10 / 56 Black System Event in South Australia (Sep 2016) Low inertia issues have been broadly recognized by TSOs, device manufacturers, academia, funding agencies, etc. MIGRATE project: M assive I nte GRAT ion of power E lectronic devices Frequency Stability Evaluation Criteria for the Synchronous Zone of Continental Europe – Requirements and impacting factors – Key events 1 RG-CE System Protection & Dynamics Sub Group However, as these sources are fully controllable, a regulation can be added to the inverter to provide “synthetic inertia”. This can also be 1 intermittent voltage disturbances due to line faults seen as a short term frequency support. On the other hand, these sources might be quite restricted with respect to the available capacity and possible activation time. The inverters have a very low overload capability compared to synchronous machines. 2 loss of synchronism between SA and remainder of the grid Renewable and Sustainable Energy Reviews 55 (2016) 999 – 1009 Contents lists available at ScienceDirect 3 SA islanded: frequency collapse in a quarter of a second Renewable and Sustainable Energy Reviews journal homepage: www.elsevier.com/locate/rser The relevance of inertia in power systems ERCOT CONCEPT PAPER PUBLIC Pieter Tielens n , Dirk Van Hertem Impact of Low Rotational Inertia on Future Ancillary Services in ERCOT ELECTA, Department of Electrical Engineering (ESAT), University of Leuven (KU Leuven), Leuven, Belgium and EnergyVille, Genk, Belgium Power System Stability and Operation ERCOT is recommending the transition to the following five AS products plus one additional AS Andreas Ulbig, Theodor S. Borsche, Göran Andersson that would be used during some transition period: “ Nine of the 13 wind farms online did not ride through the 1. Synchronous Inertial Response Service (SIR), ETH Zurich, Power Systems Laboratory Physikstrasse 3, 8092 Zurich, Switzerland 2. Fast Frequency Response Service (FFR), 3. Primary Frequency Response Service (PFR), six voltage disturbances experienced during the event.” ulbig | borsche | andersson @ eeh.ee.ethz.ch 4. Up and Down Regulating Reserve Service (RR), and 5. Contingency Reserve Service (CR). 6. Supplemental Reserve Service (SR) (during transition period) MIGRATE consortium: green-field approach to control of zero-inertia grids 1 AEMO: Update Report - Black System Event in South Australia on 28 September 2016 11 / 56 12 / 56
Low-inertia issues close to home Obvious insight: loss of inertia & frequency stability We loose our giant electromechanical low-pass filter: 2001 2002 θ , ω 2003 2004 2005 2006 2007 2008 2009 30000 2010 τ m 25000 generation M d demand 20000 dt ω ( t ) = P generation ( t ) − P demand ( t ) τ Duration [s] 15000 Events [-] 10000 5000 change of kinetic energy = instantaneous power balance M 0 Number * 10 Months of the year # frequency violations in Nordic grid Number * 10 Duration 50 (source: ENTSO-E) same in Switzerland (source: Swissgrid) 49.8 M J f [Hz] 49.6 49.4 49.2 t eal 49 0 5 10 15 20 25 30 35 Time t [s] a day in Ireland (source: F. Emiliano) a year in France (source: RTE) 13 / 56 14 / 56 15 Berlin curves before and after re-connecting to Europe Source: Energie-Museum Berlin loss of 1200 MW obvious insights lead to loss of 2500 MW Berlin re-connected to Europe obvious (naive) answers islanded Berlin grid loss of 146 MW 15 / 56
Baseline solution: virtual inertia emulation Outline !""" #$%&'%(#!)&' )& *)+"$ ','#"-'. /)01 23. &)1 2. -%, 2456 5676 !"#$%&'"'() %* +$,(-.'() /'-#%(-' !89:;8;<=><? />@=AB: !<;@=>B >< CD!EFGBH;I .( 0.1$%2$.3- 4-.(2 5.$)6,7 !('$)., Introduction +><I *JK;@ E;<;@B=>J< 8.".-9 :%(. ! "#$%&'# (&)*&+! ,--- ; :6$<,(,$,<,(, =%%77, ! (&)*&+! ,--- ; ,(3 06>67 ?@ ?9,(3%$>,$ ! (&)*&+! ,--- -JLB88BI@;MB DBNLB@> -J?LBIIB8 %@B<> ! "#$%&'# (&)*&+! ,--- . B<I "LBO D1 ":F'BBIB<P ! "&'./+ (&)*&+! ,--- !"#$%&'()*+,-+#'"(./#0*/1(2-33/*04($(5&*0-$1(( Virtual synchronous generators: A survey and new perspectives 6#+*0&$(7*/8&9+9(:"(!&;0*&:-0+9(<#+*="(20/*$=+( System Level: Optimal Placement of Virtual Inertia Hassan Bevrani a,b, ⇑ , Toshifumi Ise b , Yushi Miura b a Dept. of Electrical and Computer Eng., University of Kurdistan, PO Box 416, Sanandaj, Iran 0/(6;/1$0+9(7/>+*(2";0+%;(( b Dept. of Electrical, Electronic and Information Eng., Osaka University, Osaka, Japan network, disturbances, & performance metrics matter !""" #$%&'%(#!)&' )& *)+"$ ','#"-'. /)01 23. &)1 2. -%, 2456 ?$-0@&+*(!+1&11+A( !"#$"%&'())) A(B*-#/()*$#C/&;A( *"+,-%'!"#$"%&'())) A($#9(?&11+;(D$1$*$#=+( !789:;< "=>?<:;@7 (@7:9@? ':9<:8AB C@9 !"#$%&#'$%()*+'",'"%-#,.%/#",012%3#*',#4% /'(DE/F( #9<7G=;GG;@7 'BG:8=G 5,)"16'% Device Level: Proper Virtual Inertia Emulation Strategy H;8I8; JK>. (<=LI8?? F1 M@@:K. N9<;7 *1 %O<=. %7O98P H1 $@GQ@8. <7O (K9;G N1 M9;AK: 7898:%+1*%;'<'*=''4> ? %@%58;8A8%$'%A11* ? @% !"#$%&'("()"&*'+,,, @%98%/1"'21 B %1*$%38%/#<<4.'" C @% maybe we should not think about frequency and inertia !"#$%&'("()"&'+,,, % M d A Foundational Control Approach dt ω ( t ) = P generation ( t ) − P demand ( t ) ≈ derivative control on ω ( t ) restart from scratch for low-inertia systems Conclusions ⇒ focus today: where to do it? how to implement it properly? . . . we are not just loosing inertia . . . what else to do ? 16 / 56 Virtual inertia is becoming a technology and a product so let’s see how we can make use of it optimal placement of virtual inertia 17 / 56
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