Center for Power Electronics Systems The Bradley Department of Electrical and Computer Engineering College of Engineering Virginia Tech, Blacksburg, Virginia, USA A part of Grid Technologies Collaborative within Intergrid: A Future Electronic Energy Network? Dushan Boroyevich, Igor Cvetković, Dong Dong, Bo Wen, Rolando Burgos Presentation at Panel Session on The Impact of Microgrid Developments on Power T&D Planning and Operations University of Pittsburgh, Pittsburgh, PA 2013.11.12
US Total Energy Flow Renewables 2.27 PWh Electrical 40.7% Residential/ Commercial Nuclear 2.45 PWh 41.6 % Coal 5.79 PWh Natural Gas 6.87 PWh Industrial Petroleum 10.33 PWh 29.8 % Transportation 28.6 % Adapted from U.S. Energy Information Administration / Annual Energy Review 2009 2013.11.12 db-1
US Energy Flow in Sustainable Future? Renewables Nuclear Electrical ~ 80% Storage Assumption 2: If total energy consumption stays the same, electrical grid has to double! Residential/ Commercial 40 % Biofuels Natural Gas Petroleum Assumption 1: Up to 80% of total energy consumption will be supplied by electricity in a sustainable future! Industrial 30 % Assumption 3: With the lifetime of electrical equipment 30~50 years, we have to rebuild the grid with double capacity in the next 20-30 years! How should we do it Transportation 30 % 2013.11.12 db-2
Renewable Electricity Futures Study by NREL DOE Office of Energy Efficiency and Renewable Energy Collaboration with more than 110 contributors from 35 orgs. Released in June 2012 Renewables to Supply 80% of US Electricity in 2050 Technology cost & performance Resource availability Demand projection Demand-side technologies Grid operations Transmission cost Only currently commercial technologies were modeled, with incremental and evolutionary improvements. Sam Baldwin, ECCE 2013, Denver, 2013 2013.11.12 db-3
Regional Energy Deployment Systems Model (ReEDS) Inputs and Outputs Rooftop capacity Compressed air energy storage Onshore and Offshore wind New transmission required by 2050 in the 80% RE-ITI scenario Million MW-Miles MW No distribution-level analysis. 2013.11.12 http://www.nrel.gov/analysis/re_futures/ db-4
Installed Capacity (GW) Renewable Electricity Futures Study Conclusions 2010 2020 2030 Year 2040 2050 1,600 1,400 1,200 1,000 800 600 400 200 0 Percent Renewable in 2050 Renewable electric energy generation from technologies that are commercially available today, in combination with a more flexible electric system, is more than adequate to supply 80% of total U.S. electricity generation in 2050 while meeting electricity demand on an hourly basis in every region of the country! http://www.nrel.gov/analysis/re_futures/ 2013.11.12 db-5
Patching-up the 20 th Century Technology Integration of grid, renewables, and storage saves money! SMART METER GRID PLUG-IN HYBRID VEH. SOLAR ARRAY TURBINE ENERGY STORAGE 120 V, 60 Hz EMI EMI EMI EMI EMI PFC PFC PFC PFC PFC μc M M μc μc Smart appliances save energy! μc μc Consumer Electronics - TV, Computer, Projector Appliances - Washer, Dryer Appliances Air Conditioner Appliances Stove/ Range/Oven CF Light (ceiling) H Lamp (floor) 2013.11.12 db-6
kwh 21 st Century Electronic Power Distribution efficient, programmable, safe, affordable Nanogrid * with the bus architecture Two voltages Wireless communication Web-based GUI Time GRID ECC PLUG-IN HYBRID SOLAR ARRAY TURBINE ENERGY STORAGE Bidirectional power conversion Separation of dynamics Integrated protection Load management DG management Data acquisition Communication Islanded operation μc 380 V, DC bus 10 kw Energy Control Center (ECC) 48 V, DC Features: μc Consumer Electronics - TV, Computer, Projector Bi-directional topology Bi-directional control system Bi-directional μc current μc limit μc M M Bi-directional decoupling due to dc-link Appliances - Washer, Appliances Air Appliances Stove/ LED light Bi-directional Dryer Conditioner EMI compatibility Range/Oven (ceilig) Low dc leakage current Low cost, high density LED light (floor) 2013.11.12 * J. Bryan, R. Duke, S. Round, 2003 db-7
DC Link Voltage [V] DC Link Voltage [V] Generator Power [kw] Generator Power [kw] Local Power Wind Turbine Control of Wind Turbine (Farm) for Satisfying Active Power Demand Rectifier stage DC Link Bus Regulator stage Filter DC or AC Bus 60 Hz Grid Power Power Grid 7 6 5 4 3 2 1 Wind Speed = 15 m/s 0 0 100 200 300 545 540 535 530 525 520 515 Power To Grid Generator Speed [r/min] 510 0 2 4 6 8 10 Time [s] G(s) Regulation with Demand Change MPPT Local Power Demand G(s) Regulation with Wind Change 7 6 5 4 3 2 545 540 535 530 525 520 515 Wind Speed = 15 m/s 1 Wind Speed = 12 m/s 0 0 100 200 300 Generator Speed [r/min] 510 0 2 4 6 8 10 Time [s] Wind generation can regulate bus voltage (and frequency)! Diode Rectifier D. Rectifier Active Rectifier G(s) A. Rectifier G(s) 2013.11.12 db-8 DC Load Motor Drive G(s) Inverter AC Bus G(s) DC Bus
Intergrid? Main AC DISTRIBUTION features: PHEV local energy generation μecc HOUSEHOLD CONSUMER PHEV ELECTRONICS DC picogrid communication and DC nanogrid No thermo-mechanical HOUSEHOLD isolation functions CONSUMER PHEV ELECTRONICS DC picogrid AC microgrid At least minimal level of and storage; Interfaces to the higher- level system through bidirectional power converters; Ability to operate in islanded mode; Extensive control capabilities; switchgear; Step-up/down and provided by the power converters (no lowfrequency AC nanogrid transformers); HVAC TRANSMISSION LARGE-SCALE POWER PLANTS AND TRANSMISSION HVDC GECC GECC NUCLEAR HYDRO TRANSMISSION PHEV DC picogrid PHEV NUCLEAR DC DISTRIBUTION DC nanogrid COMBUSTION HOUSEHOLD CONSUMER ELECTRONICS DC microgrid HVAC TRANSMISSION 2013.11.12 db-9 μecc
Power angle of Gen. 1 [ ] Gen. 2 (192 MVA) Load 2 7 8 9 3 @ 5s Instability in Traditional System Caused by Partial Loss of Generation Load 5 6 Load Gen. 3 (128 MVA) 30 25 P Total Load 180 MVA < P Gen. 1 + P Gen. 3 WECC 9-bus system Gen. 1 1 4 (247.5 MVA) Total generating capacity > 550 MVA 20 15 10 5 0 0 2 4 6 8 10 12 14 16 18 20 Time [s] Large transient causes overall system instability due to undamped power oscillations between Generators 1 and 3. 2013.11.12 db-10
Frequency Variations during 2008 Florida Blackout 2013.11.12 db-11
Power at Bus 1 [MW] Equivalent Power Angle [ ] Mitigating Instability with Power Electronics-Interfaced Renewable Generation Gen. 2 (192 MVA) AC/DC Load 2 7 8 9 3 @ 5s AC/DC DC Link Renewable Generation (100+ MW) Load Full-Power Grid-Interface Converter DC/AC 5 6 Load 1 4 Not operating at peak power but regulating voltage and frequency! Total generating capacity < 450 MVA Gen. 3 (128 MVA) 80 60 40 20 0-20 -40 P Total Load 180 MVA < P Ren. + P Gen. 3 Fast-reacting power electronics can dispatch necessary active and reactive power very fast and hence stabilize the system! 0 2 4 6 8 10 12 14 16 18 20 Time [s] 2013.11.12 db-12 50 40 30 20 10 0-10 Active Power Reactive Power
Intergrid: Hierarchical network of dynamically-decoupled, electronically-interconnected, sub-networks AC DISTRIBUTION PHEV μecc HVAC TRANSMISSION LARGE-SCALE POWER PLANTS AND TRANSMISSION HVDC GECC GECC NUCLEAR HYDRO TRANSMISSION NUCLEAR COMBUSTION HVAC TRANSMISSION PHEV μecc PHEV DC picogrid PHEV DC picogrid DC nanogrid AC nanogrid HOUSEHOLD CONSUMER ELECTRONICS AC microgrid HOUSEHOLD CONSUMER ELECTRONICS PHEV DC picogrid DC DISTRIBUTION DC nanogrid HOUSEHOLD CONSUMER ELECTRONICS DC microgrid 2013.11.12 db-13
Planned Future HVDC Projects by 2020 in China 2013.11.12 db-14
Research Needed to Replace Electric Energy Railways with Highways 1. Network Architectures and Control Hierarchical network of dynamically-decoupled, electronically-interconnected, sub-networks Distributed generation, storage, loads, and intelligence Continuous control of all energy flows Enabling of efficient market mechanisms 2. High-Power and High Power-Density Converters New materials, active and passive devices, thermal management High-density integration and packaging, especially HIGH-VOLTAGE technologies and UNDERGROUND transmission / distribution 3. Safety and Reliability Security and availability (need to prove that decoupled networks are inherently more robust and resilient) Safety & protection (need to prove that DC with VSC & bi-cables could be safer than AC) Reliability & lifetime (need to prove that electronics is inherently more reliable than electro-mechanics) 2013.11.12 db-15