(BI)PV challenges. Johan Driesen KU Leuven & EnergyVille

Transcription

1 (BI)PV challenges Johan Driesen KU Leuven & EnergyVille

2 Prosumers in smart grids

3 PV & Grid issues Power Quality issues Voltage Phase Unbalance Self- consumpron is low AddiRonal loads (EVs, Heatpumps) may worsen the problem

4 New grid architectures

5 Enhancing the value of PV energy Short- term energy forecasrng Short- term energy yield predicron of PV plants can have errors > 10 % => implicarons for producer, grid operator, Meteo forecast errors Imperfect PV- plant energy yield models PV- plant producron forecast error PVSyst (15 min. resolution) Proposed model (1 sec. resolution) Ref: paper 8WeO115 - PWSEC 2014 March

6 Towards Building- Integrated- PV (BIPV) Today: PV modules added to the building typically the roof BIPV = mulr- funcronal use As building component To generate electricity Roof integration (opaque or semi-transparent) Façade integration (warm / cold) Integration as parapets and balconies Sun shading elements What will drive BIPV? Façade- integraron of PV for tall NZEB- compliant buildings poten8al market > 100 GW/yr PV- roofs with improved esthercs Lower overall cost (building + PV) 6

7 Building- Integrated- PV (BIPV) Demonstrators and facilijes Back- contact ( MWT ) Si- PV modules roofop & roofile / improved esthejcs / higher efficiency / cost- effecjve Si- PV Organic- PV facades / semi- transparent / color- on- demand TesJng and modelling interacjon PV <- > building Hygrothermal & mechanical / model & lab validajon 7

8 Towards reconfigureable modules? Concept: re- configure substrings of module to maximize power output also under non- uniform condijons This example: Each substring 1 chip with basic DC/DC converter* 4 switches 1 full- featured DC/DC converter per module ( #10) * except # 10 Patent applica&on WO 2013/ A2: energy- yield under condi&ons of variable shading (F. CaLhoor e.a.) 8

9 ConfiguraJon under uniform operajon All substrings connected in parallel Module- level DC/DC converter (#10) converts power from all substrings 9

10 ConfiguraJon under non- uniform operajon Converters 1, 3, 7, 9 also acjvated Module- level DC/DC converter acjve (#10) => can recover up to 80 % of energy lost in substring CriJcal: balance between - addijonal complexity & cost - enhanced energy yield 10

11 standard string inverter architecture (large > 3kWp) DC bus (~ 700V) GRID Storage 11

12 AC micro- inverter based architecture (large > 3kWp) DC/AC microinverter (~ 300W) AC (~ 230V) Bidirectional converter ( > 3000W) GRID Storage 12

13 DC micro- converter based architecture (large > 3kWp) DC/DC microconverter (~ 300W) with interleaved topology DC bus (~ 700V) Storage DC/AC bidirectional inverter with grid support and (quasi-)resonant topology GRID 13

14 architectures comparison (Full opjon : including storage, grid inverter with services) Standard string inverter architecture AC micro- inverter architecture DC micro- converter architecture Roof/facade ease of installajon Upgradeability MPPT performance - / Up- Jme - - /+ ++ Monitoring and maintenance Day- >Night shif effecjvity Grid Voltage Services Grid Reserve Services Purchase cost

15 Grid & storage Inverters Grid Services ReacJve power control, AcJve power control SMA; Danfoss; Power- One Storage SMA Sunny Island Nedap Meta-pv project 15

16 Grid- side converter needs to be smart grid compajble ancillary services voltage support capable of offering reserves blocking net feed- in new grid codes (e.g. Germany)? with communicajon interface for aggregator/dso communicajon high- efficiency Increased compactness hard to implement in small 1- phase unit 16

17 BidirecJonal Dual AcJve Bridge Inverter TradiJonal: dual- stage This work: single- stage PFC Rectification + voltage boost Power factor correction (PFC) Isolated DC- DC converter Galvanic isolation Output voltage regulation SR Quasi lossless rectification Can be integrated Isolated DC- DC converter Power factor correction (PFC) Galvanic isolation Output voltage regulation 17

18 Prototype DAB AC- DC converter prototype According to predefined specificajons Recursive design procedure and MOO opjmizajon 18

19 Design Requirement for Intra- module DC- DC Converter Wide input voltage range to operate the converters dynamically, depending on the mismatches present. High voltage gain (>10) to boost Jll high output voltage to avoid several stages of power conversion before connecjng to DC/AC inverter. High switching frequency to build compact (magnejcs!) & cost effecjve converter to interface at string level Lower power rajng to interface at string level Low output ripple to avoid MPPT fluctuajon Higher efficiency Transformer less non- isolated converter to make compact and cost effecjve converter 19

20 DC/DC Topology SelecJon Integrated muljplier capacitors in a classical boost converter for high gain. Simple topology Av = (M+1) / (1- D) ; M is no. of muljplier stage. Possible to achieve high gain without having high voltage stress Half of voltage stress across switches due to parallel connecjon of two switches, leads Lower conducjon loss Reduce conducjon loss due to parallel connecjon of muljplier diode Possible to achieve high efficiency Interleaved operajon helps to achieve low input current ripple and lower current stress Lower ripple current for higher switching frequency operajon Transformer less converter [currently in assessment] 20

21 DC/DC operajon D5 DMUR460 D6 DMUR460 D3 DMUR460 C3 0.1u D4 DMUR460 D1 DMUR460 C1 0.1u D2 DMUR460 L1 V C6 0.1u C2 0.1u C5 10u R1 220 L2 15uH 15uH I U V V1 = 0 V2 = 12 TD = 0u TR = 10n TF = 10n PW = 1.5u PER = 2u M22LVR V2 C9 1u C12 1u 1 2 C8 1u C11 1u V1 10Vdc I U M22LVR V3 V1 = 12 V2 = 0 TD = 0.5u TR = 10n TF = 10n PW = 0.5u PER = 2u 0 Title Size A Date: <Title> Document Number <Doc> Wednesday, Nov ember 27, 2013 Rev <Rev Code> Sheet 1 of 1 21

22 What components? Choice of CoolMos MulJJuncJon MOS (e.g. OnSemi) GaN (Imec, EPC, OnSemi) SiC (diodes only) Component CharacterisaJon VIENNA converter: two BOOST stages, driven separately Vin Cin L 24 µh D1 D2 drv_g1 drv_g2 D3 (SiC) GaN HFET 1 GaN HFET 2 Cout 1 Cout 2 95,2 µf 95,2 µf RL 1 RL 2 D4 (SiC) Patent: Voltage clamping circuit and use thereof US A1 22

23 The main reason for storage in PV systems Peak shaving (grid support) Balancing Feed- in tariff Electricity cost Stand- alone operajon 23

24 Current status ResidenJal energy storage In Germany there are >35 suppliers of residenjal energy storage systems, offering about 100 different products IBC Solar Conergy Prosol Invest Solarworld Energy3000 Type Li (LFP- LTO) Li (NCA) Li (LFP) PbAc (gel) PbAc Efficiency 83% 92% 86% 94% 92% Cost ( /kwh) LifeJme (y)

25 references OpJmal ZVS ModulaJon of Single- Phase Single- Stage BidirecJonal DAB AC DC Converters. J Everts, F Krismer, J Van den Keybus, J Driesen - IEEE TransacJons on Power Electronics, 2014 à Semikron Award 2013 Appels R., Lefevre B., Herteleer B., Goverde H., Beerten A., Paesen R., De Medts K., Driesen J., Poortmans J.: " Effect of soiling on photovoltaic modules," Solar Energy vol:96, July 21-25, 2013; pp Machiels N., Leemput N., Geth F., Van Roy J., Büscher J., Driesen J.: "Design Criteria for Electric Vehicle Fast Charge Infrastructure Based on Flemish Mobility Behavior," IEEE TransacJons on Smart Grid, October 11, Tant J., Geth F., SIX D., Tant P., Driesen J.: " MulJobjecJve Ba ery Storage to Improve PV IntegraJon in ResidenJal DistribuJon Grids," IEEE TransacJons on Sustainable Energy, vol.4, no.1, January, 2013; pp Das J., Everts J., Van den Keybus J., Van Hove M., Visalli D., Srivastava K., Marcon D., Cheng K., Leys M., Decoutere S., Driesen J., Borghs G.: " A 96% Efficient High- Frequency DC DC Converter Using E- Mode GaN DHFETs on Si," IEEE Electron Device Le ers, vol. 32, issue 10, IF: 2.719, August 18, 2011; pp De Brabandere K., Bolsens B., Van den Keybus J., Woyte A., Driesen J., Belmans R.: " A Voltage and Frequency Droop Control Method for Parallel Inverters," IEEE TransacJon on Power Electronics, IF 1.753, July, 2007; pp Pepermans G., Driesen J., Haeseldonckx D., Belmans R., D'Haeseleer W.: " Distributed generajon: definijon, benefits and issues," Energy Policy, Vol.33, Issue 6, ISSN , IF 0.958, April, 2005; pp