Software Tools Supporting Village Power System Design Jean Ku APEC Village Power Workshop November 9, 2004
Why do we need new models? • Traditional Rural Electrification • Grid extensions, micro-hydro or diesels • New and Renewable Alternatives • Small-scale individual DC systems • Solar Lanterns, Solar or Wind Home Systems • Hybrid Power AC Systems • Wind, PV, Biomass, Gensets, Batteries • Mini-grids, Micro-enterprise Zones, Battery Recharging Stations
The Role of Models • Objective and subjective criteria • Computers analyze objective criteria • People analyze subjective criteria • Offers simplicity and transparency • It’s easier to weigh the quality of service issues when you have comparable cost estimates for each alternative
The Modeling Process What is the most economical way to meet a community’s power needs? • Data Inputs • Local energy resources • Community loads • Basic component costs • General maintenance costs Modeling Tools Distribution system configuration (on- vs. off-grid) ViPOR Results Basic system design Installation and O&M costs Base line cost of alternatives Yearly power production Fuel consumption Modeling Tools Power System Design HOMER, Hybrid2
NREL’s Suite of Models • ViPOR:An optimization model that determines the best mix of centralized and isolated power generation for a particular village. • HOMER:An optimization model that determines the least-cost system configuration. • Hybrid2:A simulation model to determine the cost and performance of a wide variety of power systems given the load and available resources.
Village Power Optimization Model for Renewables An optimization model to design village electrification systems, ViPOR will: • Optimize the mix of centralized and isolated generation • Select between grid extension and stand-alone systems for centralized power • Select the optimal placement of the centralized power system(s) • Determine the optimal placement of transformers • Design the optimal MV and LV distribution grid ViPOR’s optimization procedure considers costs and revenues.
ViPOR: Inputs • Location & energy requirements for expected loads • Potential locations of centralized power system(s) • Wire and transformer costs • Power generation costs for isolated and centralized power systems (can be calculated by HOMER) • Expected revenues from each load (on-grid and off-grid) • Terrain description (spatial map) • Maximum low voltage line length
ViPOR: Sample village • Water is shown in blue, forest green, grass white, and trail gray. • Green dots are houses, brown are stores, orange is church. • Yellow triangles are high-wind sites, orange is low-wind site.
ViPOR: Solution for sample village • ViPOR has chosen a high-wind site to power the centralized system • Houses not on the grid are to be given PV home systems • Red lines are MV wires, blue are LV wires • Red dots are transformers
ViPOR: Future enhancements • Explicit calculation of voltage drops • Calculation of power losses in distribution system • Multiple transformer sizes • Multiple wire sizes • Tighter integration with GIS and HOMER
What is HOMER? • A tool for comparing and evaluating micropower technology options for a wide range of applications • Village power systems • Stand-alone applications • Grid-connected systems • Conventional technologies • New technologies
What does HOMER do? • HOMER finds the combination of components that can serve a load at the lowest life-cycle cost • Shows how this result can vary given different assumptions
Technologies HOMER Can Model • Single technology systems and multiple-technology (hybrid) systems • Compare multiple combinations of different technologies
Generators • Fossil fuels • Biofuels • Cofired • Cogeneration • Up to three generators
Grid Extension • Compare to stand-alone system • Breakeven grid extension distance
Grid-connected Systems • Rate schedule • Net metering • Demand charges
Renewable Technologies • Solar PV • Wind • Biomass and biofuels • Hydro
Emerging Technologies • Fuel cells • Microturbines • Small modular biomass
Questions HOMER can Answer • Should I buy a wind turbine, PV array, or both? • Will my design meet growing demand? • How big should my battery bank be? • What if the fuel price changes? • How should I operate my system? • And many others…
Inputs • Component cost and performance data • Resource availability • Loads
Sensitivity Analysis Optimization Simulation [Energy Balance] Simulation - Optimization - Sensitivity Analysis • Simulation • Estimate the cost and determine the feasibility of a system design over the 8760 hours in a year • Optimization • Simulate each system configuration and display list of systems sorted by net present cost (NPC) • Sensitivity Analysis • Perform an optimization for each sensitivity variable
Sensitivity Analysis • Important information is very uncertain • Loads • Even if you have data loads will change with system • Resources • Data for a different place, natural variability • Costs • Fuel prices, O&M costs • Policy and market analyses requires input ranges not point estimates
Simulation Results • Cost and performance of a particular system configuration
Optimization Results • Ranked list of system configurations
Sensitivity Results • Graphs and tables
The Hybrid2 Simulation Software A tool designed to accurately predict the long term performance of a wide variety of power systems made up of conventional fuel generators, wind generators, photovoltaics and energy storage through batteries
Hybrid2 Data Requirements • Loads • Primary time series or daily load profile, including deferrable and optional loads • Site/Resource parameters • Wind speed and incident solar time series • Ambient temperature time series or nominal value • Elevation, site position and wind turbulence parameters • Power System • Configuration and components • Component performance parameters (Library) • Dispatch Strategy (Library)
Hybrid2 Analysis Procedures • Site/Resource parameters • Wind and solar time series • Ambient temperature data • Elevation, site position and wind turbulence parameters • Loads • Primary time series or daily load profile Power System Configuration and components Component performance parameters (Library) Dispatch Strategy (Library) Performance Results System design Economic Results Capital cost O&M cost Detailed Modeling
Hybrid2 Software Features • Probabilistic/time series model: Accounts for the fluctuations of the wind and load during each time step • Very diverse system architecture • AC, DC and combined systems can be modeled • System can include multiple wind turbines, multiple diesels, batteries, PV and 4 different types of power converters • Detailed economic analysis • On line library of manufactures equipment • Detailed dispatching options: 17 different control parameters • Hybrid systems glossary of commonly used terms • Energy audit/estimation tool • Resource data gap filler
Hybrid2 Power System Design The power system is designed to meet the required loads using the resources available. This requires a fair amount of hybrid system and design experience.
Hybrid2 Results Interface Simulation results displayed in a graphical format as well as a summary file which includes power flows from each component, loads, and system losses.
HOMER and Hybrid2 • Design philosophy: Simplicity vs. flexibility • Use: Optimization vs. performance predictions • System configuration: • HOMER output, Hybrid2 input • Main differences Hybrid2 HOMER - Intra-hour variability - Easy initial use • Bus voltages - Dispatch optimization • Dispatch flexibility - All DG technologies - Engineering tool - Options analysis
These are only models! • ViPOR, HOMER, and Hybrid2 do not provide "the right answer" to questions. It does help you consider important factors, and evaluate and compare options.
Model Availability • ViPOR:Available from www.nrel.gov/vipor. • HOMER:Available from www.nrel.gov/homer. Inquiries, email firstname.lastname@example.org. • Hybrid2:Send e-mail to Hybrid2@nrel.gov. Provided with software, manuals and user support. These models were developed with funding from the US Department of Energy and the National Renewable Energy Laboratory