Control of microgrids with flexible9 1 0 structure: a passivity framework 2 a h p m Giancarlo Ferrari Trecate C T E S y r é Automatic Control Laboratory École Polytechnique Fédérale de Lausanne (EPFL), Switzerland n 2 F d P E 07 February 2019
Outline Decentralized control design for systems with flexible structure DC microgrids: primary voltage control A passivity framework for stability of interconnected systems DC microgrids: passivation of different generation units Conclusions and perspectives
Systems with flexible structure 2 1 3 4 Models Network of coupled subsystems Flexibility: subsystems enter/leave faulty components, hardware upgrade, subsystem addition,
Systems with flexible structure 2 1 3 4 Models Network of coupled subsystems Flexibility: subsystems enter/leave faulty components, hardware upgrade, subsystem addition, Control architecture Decentralized/distributed How to design local controllers without a global model? when subsystems plug in/out?
Scalable design 2 1 3 4 Decentralized design Pros [Bailey 66], [Findeisen 82], [Bakule & Lunze, 88]... Scalable algorithm Coupling-independent properties Privacy compliant
Scalable design 2 1 3 4 5 Decentralized design Pros [Bailey 66], [Findeisen 82], [Bakule & Lunze, 88]... Scalable algorithm Coupling-independent properties Privacy compliant Subsystem plug-in: no need to update other controllers
Scalable design 2 1 3 4 5 Decentralized design Pros [Bailey 66], [Findeisen 82], [Bakule & Lunze, 88]... Scalable algorithm Coupling-independent properties Privacy compliant Subsystem plug-in: no need to update other controllers Cons: limited information When decentralized design is feasible? 1
Decentralized design of primary voltage control in DC microgrids
DC microgrids E S C T a h 2 y r é p m 9 1 0 Courtesy of Siemens Energy Networks of distributed generation units (DGUs) and loads P E Technology drivers for DC microgrids DC loads and storage: servers, electric vehicles, batteries... Renewable DC sources: PV panels,... n 2 F d Key challenge in islanded mode control of individual DGUs for voltage stabilization, current sharing,
DC microgrids: model
DC microgrids: model Buck i RL filter i V ti I ti PCC i Low-voltage DGU - Buck converter with RLC filter I Li C ti V i R ij Coupling L ij Control input
DC microgrids: model Buck i RL filter i V ti I ti PCC i Low-voltage DGU - Buck converter with RLC filter I Li C ti V i - ZIP load at PCC R ij L ij
DC microgrids: model Buck i RL filter i V ti I ti PCC i Low-voltage DGU - Buck converter with RLC filter - ZIP load at PCC I Li C ti V i R ij L ij DGUs connected by RL lines
DC microgrids: voltage control Buck i RL filter i V ti I ti PCC i I Li C ti V i Goal: tracking of voltage references at PCCs irrespectively of coupling/loads Related works under simplifying model assumptions: [Tucci et al. 16], [Zhao et al. 15], [De Persis et al. 18],... R ij L ij
DC microgrids: voltage control Buck i RL filter i V ti I ti PCC i I Li C ti V i R ij L ij M. Tucci, S. Riverso, and G. Ferrari-Trecate. Line-independent plug-and-play controllers for voltage stabilization in DC microgrids. IEEE Transactions on Control Systems Technology, 2018
Decentralized control design Buck i RL filter i V ti I ti PCC i I Li C ti V i R ij L ij P. Nahata, R. Soloperto, M. Tucci, A. Martinelli, and G. Ferrari-Trecate. A Passivity-Based Approach to Voltage Stabilization in DC Microgrids with ZIP loads, Tech. report. EPFL and IEEE American Control Conference (ACC), 2018
Decentralized control design Buck i RL filter i V ti Main results I ti PCC i I Li C ti V i Asymptotically stable offset-free voltage tracking in the whole microgrid Decentralized design of local controllers R ij L ij P. Nahata, R. Soloperto, M. Tucci, A. Martinelli, and G. Ferrari-Trecate. A Passivity-Based Approach to Voltage Stabilization in DC Microgrids with ZIP loads, Tech. report. EPFL and IEEE American Control Conference (ACC), 2018
Why it works? Buck i RL filter i V ti I ti PCC i I Li C ti V i DGUs and lines are interconnected in a skew-symmetric, (energyneutral) fashion Asymptotic stability of the controlled microgrid R ij L ij
A passivity framework for interconnected system
Stability and skew-symmetric interconnection <latexit sha1_base64="d2x
Stability and skew-symmetric interconnection <latexit sha1_base64="d2x
Stability and skew-symmetric interconnection <latexit sha1_base64="d2x
Stability and skew-symmetric interconnection <latexit sha1_base64="d2x
Stability and skew-symmetric interconnection <latexit sha1_base64="d2x Related results: [Kiang, 2017], [Van der Schaft, 2017], [Arcak, 2016, 2007], [Burger & De Persis, 2015],
Application to DC microgrids Lines and DGUs are input-affine systems (up to a state shift) Controlled DGUs are locally passive with Lines are inherently passive with Skew-symmetric interconnection P. Nahata, R. Soloperto, M. Tucci, A. Martinelli, and G. Ferrari-Trecate. A Passivity-Based Approach to Voltage Stabilization in DC Microgrids with ZIP loads, Tech. report. EPFL and IEEE American Control Conference (ACC), 2018
Passivation of different DGU models
Voltage-controlled DGU with exponential load Buck i RL filter i V ti ZIE load at PCC I ti PCC i I Li C ti V i R ij L ij
Voltage-controlled DGU with exponential load Buck i RL filter i V ti ZIE load at PCC I ti PCC i I Li C ti V i R ij L ij
Current-controlled DGU Current tracking grid-feeding converter R. Han, M. Tucci, R. Soloperto, J. M. Guerrero, G. Ferrari-Trecate Plug-and-play current controllers for grid-feeding converters in DC microgrids IEEE Asian Control Conference (ASCC), 2017
Cluster of V-DGU and C-DGU (ZI load) Grid-feeding/forming converters[1] [1] V. Nasirian, S. Moayedi, A. Davoudi, F. L. Lewis. Distributed cooperative control of dc microgrids. IEEE Transactions on Power Electronics, 2015 [2] R. Han, M. Tucci, A Martinelli, J. M. Guerrero, G. Ferrari-Trecate Stability Analysis of Primary Plug-and-Play and Secondary Leader-based Controllers for DC Microgrid Clusters IEEE Transactions on Power Systems,2018, online
Medium-voltage DGUs Nonlinear dynamics of Boost converter The DGU can be passivated by a nonlinear controller Monday's poster session A Martinelli, P. Nahata, G. Ferrari-Trecate Voltage Stabilization in MVDC Microgrids Using Passivity-Based Nonlinear Control, IEEE Conference on Decision and Control (CDC), 2018
Experiments 2 y (Intelligent Microgrid Laboratory, Aalborg University) r é p m a h Microgrid topology L 3 R 12 L2 R13 DGU 1 3 12 DGU 2 R2 n 2 F d P E E S C T 9 1 0 L13 DGU 3 Ring electrical topology ZI loads Communication network
Experiment stages t = 0 s: DGU 2 DGU 1 DGU 3 Secondary layer disabled DGUs isolated and equipped with voltage controllers I t (A) V PCC (v) V av (v) 1.5 1 0.5 48.4 48.2 47.8 47.6 47.4 I t1 I t2 I t3 0 0 5 10 15 20 25 30 35 40 48 48.4 48.2 48 47.8 47.6 47.4 Plug-in of DGUs and lines Secondary control active V PCC1 V PCC2 V PCC3 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 time (s)
Experiment stages R 12 L 12 DGU 2 DGU 1 DGU 3 Secondary layer disabled t = 2.5 s: DGUs 1 and 2 connected together I t (A) V PCC (v) V av (v) 1.5 1 0.5 48.4 48.2 47.8 47.6 47.4 I t1 I t2 I t3 0 0 5 10 15 20 25 30 35 40 48 48.4 48.2 48 47.8 47.6 47.4 Plug-in of DGUs and lines Secondary control active V PCC1 V PCC2 V PCC3 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 time (s) Voltage stability and fast transients
Experiment stages R 12 L 12 DGU 2 R 13 L 13 R 23 L 23 DGU 1 DGU 3 Secondary layer disabled t = 5 s and t = 10 s: connect DGUs 1-3 and 2-3 (electrical ring) I t (A) V PCC (v) V av (v) 1.5 1 0.5 48.4 48.2 47.8 47.6 47.4 I t1 I t2 I t3 0 0 5 10 15 20 25 30 35 40 48 48.4 48.2 48 47.8 47.6 47.4 Plug-in of DGUs and lines Secondary control active V PCC1 V PCC2 V PCC3 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 time (s) Safe and stable plug-in operations
Experiment stages R 12 L 12 DGU 2 R 13 L 13 R 23 L 23 DGU 1 DGU 3 Secondary layer enabled t = 15 s: Goal: same current for all DGUs I t (A) V PCC (v) V av (v) 1.5 1 0.5 48.4 48.2 47.8 47.6 47.4 I t1 I t2 I t3 0 0 5 10 15 20 25 30 35 40 48 48.4 48.2 48 47.8 47.6 47.4 Plug-in of DGUs and lines Secondary control active V PCC1 V PCC2 V PCC3 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 time (s)
Experiment stages R 12 L 12 DGU 2 R 13 L 13 R 23 L 23 DGU 1 DGU 3 Secondary layer enabled t = 25 s: Load switch at PCC3 I t (A) V PCC (v) V av (v) 1.5 1 0.5 48.4 48.2 47.8 47.6 47.4 I t1 I t2 I t3 0 0 5 10 15 20 25 30 35 40 48 48.4 48.2 48 47.8 47.6 47.4 Plug-in of DGUs and lines Secondary control active V PCC1 V PCC2 V PCC3 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 time (s)
Conclusions and perspectives
Conclusions and perspectives 1176 Decentralized control design for systems with flexible structure Stable and safe plug-in/out of subsystems Passivity-based control of DC microgrids Offset-free voltage tracking For AC microgrids with clock synchronisation IEEE TRANSACTIONS ON SMART GRID, VOL. 6, NO. 3, MAY 2015 Plug-and-Play Voltage and Frequency Control of Islanded Microgrids With Meshed Topology Stefano Riverso, Member, IEEE, Fabio Sarzo, and Giancarlo Ferrari-Trecate, Senior Member, IEEE 2 1 3 4
Conclusions and perspectives 1176 Decentralized control design for systems with flexible structure Stable and safe plug-in/out of subsystems Passivity-based control of DC microgrids Offset-free voltage tracking For AC microgrids with clock synchronisation IEEE TRANSACTIONS ON SMART GRID, VOL. 6, NO. 3, MAY 2015 Plug-and-Play Voltage and Frequency Control of Islanded Microgrids With Meshed Topology Stefano Riverso, Member, IEEE, Fabio Sarzo, and Giancarlo Ferrari-Trecate, Senior Member, IEEE Current/future research Cybersecurity for networked secondary layers (see poster session) Coupling with EMS for long-term operation 2 1 3 4
Acknowledgements @ EPFL Pulkit Nahata Mustafa Turan @ Università di Pavia Fabio Sarzo Michele Tucci @ Aalborg University Josep Guerrero Juan Carlos Vasquez Renke Han @ UTRC Stefano Riverso @ University of Stuttgart Raffaele Soloperto @ ETH Andrea Martinelli
j k Secondary consensus layer m Itj 1 s Itj Network Itk n i Vi ++ Local controller 1 s Itk +- 1 s Iti RL filter Vti Buck i Plug-in of DGUs and lines It (A) 0.5 48.4 48.2 48 47.8 47.6 47.4 V PCC (v) F d V av (v) n 2 0 5 P E 10 10 a h DGU i C T 15 15 20 20 25 30 V 25 PCC1 30 I t1 I t2 I 35 V PCC2 35 t3 40 V PCC3 40 Thanks! 48.4 48.2 48 47.8 47.6 47.4 0 5 10 15 20 time (s) 2 y r é p m DGU j ILi E S 1 5 line ij Vi Secondary control active 1.5 0 Iti Cti Primary control layer 0 ki s Communication Vref,i 9 1 0 +- 25 30 35 40