Communication and Control for Microgrid Optimal Energy Efficiency Rui Zhou, Sumit Bose, Santosh Veda Oct 10 th 2013 GE Global Research RPI Microgrid Workshop
Overview Microgrid Characteristics Microgrid Optimization Optimal Dispatch Volt/VAR support Battery Energy Storage System Field Demonstration Future Research DC Microgrid 1
Microgrid Characteristics Combination of conventional and/or renewable on/off the grid energy sources Energy storage system to compensate for renewable intermittency Communication networking of all Microgrid elements including load clusters Integration with Protection Controls to ensure reliable operation Wind Generation Diesel or Natural Gas Generation A smart control system to optimize and manage generators, energy storage and loads within the microgrid 2
Power Optimal Dispatch The process of allocating the required load demand between the available resources such that the cost of operation is minimized. The optimal dispatch algorithm implements Model Predictive Control using: Load forecasts Renewable generation forecasts (wind, hydro, solar, bio-mass) and Stored Energy 24 hr U90Plus System Topology, Fuel Cost, Start-up/Shut-down Costs, Isoch Margin,... S E T T I N G S Time Device Status Storage State of Charge Pre-proccesing Unit Microgrid Optimization Model Post-proccesing Unit Setpoints of Dispatchables Setpoints of Storage Devices F O R E C A S T S Load Renewables Electricity Price 3
Building Thermal Load Management Time Building Load (kw) Building temperature raised by a few degrees without compromising comfort Load came down almost instantly Kept low for 30 minutes Allowed enough time to observe any rebound effect after restoration of load. A sizable amount of electric load can be dropped instantly by managing the building loads. About 10% of load rebound was observed after restoration. 4
Thermal v.s. Electrical Optimization Higher Benefits Expected with Larger Number of Assets 5
Renewable Utilization Take full account of renewables in the cost output The difference in cost with and without renewables in day should be the reflection of the renewable energy contribution Test Condition Optimal Cost (%) System running with renewables (PV) enabled 100.0% Output from next dispatch cycle after renewables are disabled at 6:45am (sun just coming up) 104.7% Output at 10:30pm after the full PV cycle. Peak PV during the day was 865kW 105.4% Output from next dispatch cycle after renewables are reenabled at 10:30pm 100.1% Optimal cost rises without renewables. The rise in cost is close to the energy provided by PV in a day. 6
Volt/Var Control Minimize peak load (through conservation voltage reduction) Minimize line power losses Minimize number of cap bank operations Voltage falttening Renewable assets volt/var support 7
Feeder Voltage (pu) Volt/VAr Support from PV System Voltage variation is caused by the interaction of power output with system resistance 1.05 1.04 1.03 1.02 1.01 1.00 7:00 AM 11:00 AM 3:00 PM 7:00 PM Hour V P V R Q V X 8
Battery Energy Storage System Grid-Tied, Volt/VAR, phase imbalance, and real power injection capable to. Increase Power Factor of Co-Generation facility Increase overall Solar Power Plant capacity factor, specifically during islanded operation Provide peak-shaving during high demand periods and reduce peak demand charges GE Durathon Battery Grid Tied Inverter 9
Bella Coola Microgrid Benefits: Reduced use of fossil fuel based generation 10
29 Palms Microgrid (Grid Connected) Bulk Grid Electrical Distribution Features: Energy & cost optimization Volt / VAR control Energy storage AA-Sub EE-Sub CHP Joshua Heights N-Sub Fairway Heights HQ Chillers CH Chilled Water Loop Boilers Battery Energy Storage BESS +/- PV Critical Loads CoGen1 Heat Recovery HTHW Photovoltaic Arrays Energy Storage Benefits Power factor of Co-gen facility Solar plant capacity factor, especially during islanded operation Provide peak shaving during high demand periods and reduce peak demand charges Application specifics 10-20 MW power demand 7 MW Co-gen power plant 1 MW Photovoltaic 240 kw/ 480 kwh battery Team: GRC, GE Digital Energy, 3 rd Party
Future Research DC Microgrid Higher energy efficiency Variable speed operation of generators Higher efficiency integration of PV, batteries, fly wheels, etc. Increase capacity factor of renewables with energy storage Lower cable losses Lower footprint and lower cost Transformerless (solid state and/or high frequency transformer) Eliminate redundant power conversion stages Lower cable cost Safer/Resilience Faster fault detection and isolation Better power flow control 12
GE Products & Solutions For Microgrids GE Microgrid Offering a System Solution 13
U90Plus Distinctive Features Support of low-intermittent renewable power sources operating in isoch mode Support of both electricity and thermal systems in a single optimization framework 15 15
Screen Shots from Twentynine Palms U90Plus Cimplicity 16