NTUA Microgrids The future of Small Grids

Transcription

1 Microgrids The future of Small Grids Nikos Hatziargyriou National Technical University of Athens, Greece

2 What are MICROGRIDS? Interconnection of small, modular generation to low voltage distribution systems forms a new type of power system, the Microgrid. Microgrids can be connected to the main power network or be operated islanded, in a coordinated, controlled way.

3 Technical, economical and environmental benefits Energy efficiency Minimisation of the overall energy consumption Improved environmental impact Improvement of energy system reliability and resilience Network benefits Cost efficient electricity infrastructure replacement strategies

4 Energy Efficiency - Combined Heat and Power 100 % 50 % electrical energy power station 50 % unused waste heat 50 % fossil fuel Prof. Dr. J. Schmid Up to now: Central power stations Decentral heat production exchange of electrical energy In Future: Decentral combined heat and power 100 % Oil / Gas 1/3 less consumption of fossil sources of energy

5 Storms (1999) 10.8 billion London (28 August 2003) Spain (Winter 2002) Climate & Power Disasters: Normal in the future? Denmark, South Sweden (23 September 2003) Floods (2002) 30 billion Croatia Heatwave(23 Septemb (2003) 2003) 20,000 deaths? Italy (28 September 2003) Greece (12 July 2004)

6 50 million customers in USA and Canada MW lost 11 % Cost 4 10 billion $ US

7 Potential for DG to improve service quality Voltage level G G G G G G Central generation DG - Medium scale DG DG DG Small-scale DG Distribution of CMLs Security of supply Security of supply

8 CIGRE SC NTUA Installation and Replacement time Distributions of Substation Equipment

9 Network Benefits Value of Micro Generation ~ /kwh Central Generation ~ /kwh Transmission HV Distribution ~ /kwh ~ /kwh MV Distribution LV Distribution Micro Generation

10 Technical Challenges for Microgrids Relatively large imbalances between load and generation to be managed (significant load participation required, need for new technologies, review of the boundaries of microgrids) Specific network characteristics (strong interaction between active and reactive power, control and market implications) Small size (challenging management) Use of different generation technologies (prime movers) Presence of power electronic interfaces Protection and Safety

11 Market and Regulatory Challenges coordinated but decentralised energy trading and management market mechanisms to ensure efficient, fair and secure supply and demand balancing development of islanded and interconnected price-based energy and ancillary services arrangements for congestion management secure and open access to the network and efficient allocation of network costs alternative ownership structures, energy service providers new roles and responsibilities of supply company, distribution company, and consumer/customer

12 EC MICROGRIDS Project Large Scale Integration of Micro-Generation to Low Voltage Grids Contract : ENK5-CT GREAT BRITAIN UMIST URENCO PORTUGAL EDP INESC SPAIN LABEIN 14 PARTNERS, 7 EU COUNTRIES UMIST URENCO ARMINES EDF ISET SMA GREECE NTUA PPC /NAMD&RESD GERMANOS GERMANY SMA ISET NETHERLANDS EMforce INESC EDP LABEIN CENERG ICCS / NTUA GERMANOS FRANCE EDF Ecole des Mines de Paris/ARMINES CENERG PPC/NAMD&RESD

13 R&D Objectives Contribute to increase the share of renewables and to reduce GHG emissions; Study the operation of Microgrids in normal and islanding conditions; Optimize the operation of local generation sources; Develop and demonstrate control strategies to ensure efficient, reliable and economic operation; Simulate and demonstrate a Microgid in lab conditions; Define protection and grounding schemes; Define communication infrastructure and protocols; Identify legal, administrative and regulatory barriers and propose measures to eliminate them;

14 Microgrids Highlights Control philosophies (hierarchical vs. distributed) Energy management within and outside of the distributed power system Device and interface response and intelligence requirements Quantification of reliability benefits Steady State and Dynamic Analysis Tools Laboratory Microgrids

15 Microgrids Hierarchical Control MicroGrid Central Controller (MGCC) promotes technical and economical operation, interface with loads and micro sources and DMS; provides set points or supervises LC and MC; MC and LC Controllers: interfaces to control interruptible loads and micro sources PV MC Flywheel AC DC DC AC LC MC LC MC AC DC Storage LC MC ~ CHP DMS MV MGCC LV MC AC DC ~ Micro Turbine LC MC AC DC Fuel Cell Centralized vs. Decentralized Control

16 MultiAgent System for Microgrids Autonomous Local Controllers Distributed Intelligence Reduced communication needs Open Architecture, Plug n Play operation DNO MO Grid Level FIPA organization Java Based Platforms Agent Communication Language Agent Microgrid... Microgrid Management Level Agent Agent Agent Microgrid MGCC LC LC LC LC... Field Level Agent Agent Agent Agent

17 Participation of Microgrids in Energy Markets Microgrid Serving its own needs using its local production, when beneficial (Good Citizen) MGCC minimises operation costs based on: Prices in the open power market Forecasted demand and renewable power production Bids of the Microgrid producers and consumers. Technical constraints Microgrid buys and sells power to the grid via an Energy Service provider (Ideal Citizen) MGCC maximizes value of the Microgrid, i.e. maximizes revenues by exchanging power with the grid based on similar inputs

18 Off-load TC kv in 5 steps 0.4 kv 20 kv 3+N 20/0.4 kv, 50 Hz, 400 kva u k =4%, r k =1%, Dyn11 3 Ω Study Case LV Feeder with DG sources Flywheel storage Rating to be determined Wind Turbine 3Φ, 15 kw Photovoltaics 1Φ, 4x2.5 kw Single residencial consumer 3Φ, I s =40 A S max =15 kva S 0 =5.7 kva Group of 4 residences 4 x 3Φ, I s =40 A S max =50 kva S 0 =23 kva Fuel Cell 3Φ, 30 kw ~ ~ 3+N+PE Circuit Breaker Possible sectionalizing CB Appartment building 1 x 3Φ, I s =40 A 6 x 1Φ, I s =40 A S max =47 kva S 0 =25 kva 3+N+PE 3+N+PE 1+N+PE Circuit Breaker instead of fuses 3+N+PE 80 Ω 10 Ω 30 Ω 30 Ω 4x6 mm 2 Cu 20 m 80 Ω 4x16 mm 2 Cu 30 m 4x25 mm 2 Cu 20 m 80 Ω 80 Ω 4x16 mm 2 Cu 30 m 80 Ω 3+N Overhead line 4x120 mm 2 Al XLPE twisted cable Pole-to-pole distance = 35 m 80 Ω 80 Ω 80 Ω 3x70mm2 Al XLPE mm 2 AAAC Twisted Cable 10 Ω 80 Ω 3+N+PE 4x6 mm 2 Cu 20 m 80 Ω 30 m Appartment building 5 x 3Φ, I s =40 A 8 x 1Φ, I s =40 A S max =72 kva S 0 =57 kva 3+N+PE Possible neutral bridge to adjacent LV network 2 Ω Other lines 3x50 mm 2 Al +35mm 2 Cu XLPE ~ ~ ~ Single residencial consumer 3Φ, I s =40 A S max =15 kva S 0 =5.7 kva Photovoltaics 1Φ, 3 kw Microturbine 3Φ, 30 kw

19 Highlight: MGCC Simulation Tool

20 Residential Feeder with DGs Good Citizen Cost Reduction : % 27% reduction in CO 2 emissions Model Citizen Cost reduction : 18.66% kw Load & Power exchange with the grid (residential feeder) Hour Pow er exchanged w ith the grid Load Pattern

21 Highlight: Reliability Assessment System Maximum Load Demand: 188 kw Capacity of System Infeed: 210 kw (100%) Installed DGs: 15 kw Wind, 13 kw PVs, 30 kw Fuel Cells, 30 kw Microturbines Infeed Capacity 100% FLOL (ev/yr) LOLE (hrs/yr) LOEE (kwh/yr) (no DGs) 2,130 23, ,03 Infeed Capacity 80% (no DGs) 58,14 124, ,52 Infeed Capacity 80% (with Wind + PV) 14,02 41, ,41 Infeed Capacity 80% (all DGs) 2,28 15,70 716,36

22 DeMoTec at ISET

23 Laboratory installation at NTUA P load 400 P (W) P bat P pv P grid Time (s) U mg f (Hz) f grid U (V) U grid f mg Time (s) Time (s)

24 Implementation of the flywheel energy storage system by UM Flywheel Inverter interface

25 Development of Electronic Switch v MicroGrid [v] I MicroGrid [A] I Grid [A] grid connected island time [ms]

26 Highlight: Modelling and Simulation Two battery invs + two PVs + one WT - Isolation + wind fluctuations P,Q per phase Battery Inverter A I per phase Battery Inverter A

27 Conclusions Microgrids: A possible paradigm for future LV power systems Distinct advantages regarding efficiency, reliability, network support, environment, economics Challenging technical and regulatory issues Promising solutions, needs for field demonstrations