A Battery Equivalent Model for DER Services

Transcription

1 GridWise Architecture Council A Battery Equivalent Model for DER Services June 13-15, Portland, Oregon Rob Pratt Mgr., Distribution and Demand Response Sector Pacific Northwest National Laboratory

2 Presentation Agenda What is a battery equivalent model, and why should we care? Description of the project developing it (use case 1) How the battery equivalent model works for various DERs Applications in transactive systems 2

3 What is a Battery Equivalent Model? Why should we care? A common, uniform means of representing the properties of any DER- ( device- ) fleet as a virtual battery i.e., in terms used to characterize battery/inverter systems extended with additional generalized properties and constraints needed to describe other types of DERs like a virtual power plant, except more general. Provides level-playing field for DER participation in terms of how they are dispatched (in planning & operations models) Provides a battery-equivalent metric for grid flexibility added Allows contribution of different types of DERs to be summed 3

4 Description of the Project Developing the Battery Equivalent Model DOE Grid Modernization Laboratory Consortium Project Standards and Testing for Grid Services from Devices Characterization test protocol and model-based performance metrics for devices ability to provide a broad range of grid services, i.e., provide the flexibility required to operate a clean, reliable power grid at reasonable cost. Simple, low-cost testing protocols manufacturers can use to characterize equipment performance General, standard device model reflecting test results for each device class Proven means of estimating performance metrics for a standard set of grid services from the test results Protocol can be regionalized to reflect local markets, new services, weather, loads, etc. 4

5 Description of the Project Developing the Battery Equivalent Model (cont.) Project is about Enhancing Empowering Unlocking Unleashing the value of grid modernization devices everywhere! Reward innovation, help manufacturers understand opportunities, enlarge the market for their devices Validated performance & potential value for grid operators help with decisions on purchases, programs, subsidies, rebates, markets, planning and operations Independently validated information for consumers & 3 rd parties for purchase decisions 5

6 Device (DER) Classes Involved Responsive, flexible end-use loads Water heaters Refrigerators Air conditioners Commercial rooftop units (RTUs) Commercial refrigeration Commercial lighting Electric vehicles (charging only) Electrolyzers Storage Battery / inverter systems Thermal storage systems Electric vehicles / inverters (full vehicle-to-grid) Distributed generation Photovoltaic (PV) solar / inverter systems Fuel cell / inverters 6

7 Grid Services Involved Peak load management (capacity) Energy market price response (e.g., retail rate reflecting wholesale energy cost) Capacity market resource dispatch (market value) Frequency regulation (market value) Spinning reserve (market value) Ramping (new) Artificial inertia (new) Distribution voltage management (new; re. PV impacts) 7

8 The Dilemma Facing the Project With 12 devices and 8 grid services developing a generic dispatch algorithm for each combination would require developing 96 device- and service-specific algorithms This would be cumbersome and inefficient How would the resulting performance ratings be comparable, if they are dependent on dispatch algorithms that differ, even in subtle or inadvertent ways? This dilemma arises many times throughout the grid when developing DER algorithms including transactive systems 8

9 Baseline usage, Balance of System, Limits Dispatch Fleet T R A N S A C T I V E E N E R G Y S Y S T E M S Use Case 1: Rating a Device s ability to Provide Grid Services Device & Controller Under Test Std. Device Assumptions Weather, Boundary Conditions Grid Service Grid Service Drive Cycles Performance Metrics Characterization Test & Apparatus Existing Industry Standards Characterized Parameters Adopted Parameters Device Model Updated Parameters Dispatch Service Power; Weather Battery- Equivalent Model Service Efficacy & Value Metrics; Energy, End-User, Equipment Impacts Advance through drive cycle time steps 9

10 Power and Energy Balance for a Generic DER Power injected into grid (P Grid ) Power to end use (P EndUse ) Parasitic power (P Parasitic ) Converter Source/Sink Power from source/sink Output from generator (P Output ) + Discharge from storage (P Discharge ) 10

11 Power/Energy Balance (cont.) and Power for Grid Services from a Generic DER Converter Source/Sink Power for Grid Service: Power injected into grid (P Grid ) P Service t = P Grid t P GridBase t ; where Base indicates base case P Service t = P Discharge t + P Output t P Enduse (t) P Parasitic Power to end use (P EndUse ) Parasitic power (P Parasitic ) Power from source/sink Output from generator (P Output ) + Discharge from storage (P Discharge ) Power Balance: P Grid t = P Output t + P Discharge t P Enduse t P Parastic (t) ; where is the difference between the service case & base case 11

12 DER Model Determines Current Parameters Device Model Inform Service of DER Constraints Nameplate capacity Energy storage capacity Energy stored Charging efficiency Discharging efficiency Maximum power for service Minimum power for service Ramp rate power up Ramp rate power down Time limit, hold Time, restoration Strike price Price elasticity Power injected into grid, basecase Step 1 Step 2 Step 3 Grid Service Initiate exchange for time interval Current time Time interval Weather data Forecast service quantity Plan response to forecast Maximize incentives earned Within operating constraints of DER Dispatch the service for time interval Power delivered for service Power injected into grid 12

13 Battery Equivalent (BEq) Representations of DERs Storage devices Building end-use loads with inherent sensible heat storage (thermal mass) Other loads & distributed generators 13

14 BEq for Storage Devices DER Class: Batteries Electric Vehicles (V2G) Electrolyzers w/ H 2 Tank Thermal Energy Storage Source/Sink Electro-chemical Electrochemical Hydrogen storage tank Thermal phase change State-of-Charge Currently stored energy as a fraction of total storage potential Converter Inverter Inverter DC power supply Refrigeration system Power to End-Use Demand for energy onboarding by vehicles Parasitic Power Make-up for losses; thermal conditioning load Make-up for thermal losses (if any) Make-up for losses; fans & pumps Power Output Power Conserved 14

15 BEq for Storage Devices (cont.) DER Class: Charging Efficiency Discharging Efficiency Max. power for service Min. power for service Time limit, hold SoC Batteries Electric Vehicles (V2G) Inverter/battery charging efficiency (current conditions) Inverter/battery discharging efficiency (current conditions) Current max. discharge rate (Current min. charge rate) Electrolyzers w/ H 2 Tank Electrolyzer efficiency 100% already in H 2 form Thermal Energy Storage (cooling) Current TES system efficiency 100% already in thermal form Power to meet current demand (i.e., meet it entirely from storage) Difference between power to meet current demand and power rating (i.e. max. increase in load) Time, restore SoC Next day Next drive time Next day Incentive response Cover conversion losses + wear + incentive 15

16 BEq for End-Use Loads with Thermal Mass DER Class: Source/Sink State-of-Charge Converter Power to End-Use Parasitic Power Power Output Power Conserved Space Conditioning Thermal mass of building Space conditioning Fans & pumps Water Heating Thermal mass of water in tank Refrigeration Thermal mass of refrigerator compartment Deviation of mass temperature from normal set point divided by allowable mass temperature range Resistive elements or heat pump (HP) Refrigeration system Electrical energy required to serve thermal demand while maintaining current mass temperature Make-up for losses; fans & pumps (HP) Make-up for losses; defrost; fans Reduced demand due to deviation of temperature from base case operation (e.g., setpoint) 16

17 BEq for Loads with Thermal Mass (cont.) DER Class: Space Conditioning Water Heating Refrigeration Charging Efficiency Discharging Efficiency Maximum power for service Minimum power for service System efficiency under current conditions 100% already in thermal form Power to meet current demand (i.e., meet it entirely from storage) Difference between power to meet current demand and power rating (i.e. max. increase in load) Time limit, hold SoC ~4 hours (?) ~15 min (?) Time, restoration ~9 pm Next day ~15 min (?) Incentive response Price elasiticity + cost of any increased consumption 17

18 BEq for Other Loads & Distributed Generators DER Class: Commercial Lighting Electric Vehicles (charging only) PV Solar Fuel Cell Source/Sink Electro-chemical battery PV array Fuel cell stack State-of-Charge Ratio of deferred charging energy to max. deferrable, or fuel tank SoC (see electrolyzer) Converter DC power supply Inverter Power to End-Use Parasitic Power Lighting load demand Power to battery charger Make-up for losses; thermal conditioning Fans & pumps Power Output AC output from inverter Power Conserved Reduction in lighting input 18

19 BEq for Other Loads & Dist. Gen. (cont.) DER Class: Charging Efficiency Discharging Efficiency Maximum power for service Minimum power for service Commercial Lighting Current demand min. power Current demand max. power Electric Vehicles (charging only) Current charging efficiency 100% simple energy deferral Current demand Current demand power rating PV Solar Current capacity current output (Current power output), i.e., curtail* Fuel Cell Power rating current output (Current power output)* Time limit, hold Time, restoration Next day Next drive time Incentive response Price elasticity * For real power; reactive power has different properties Cover lost production Cover fuel & wear 19

20 Applications of Battery Equivalent Models for Transactive Systems [DER test results Capacities for transactive bids] Use Case 2 Select (optimize) which grid service(s) to respond to (different values; some are mutually exclusive) Use Case 3 Develop (optimize) response plan for each service to (~24-hr) forecasts of forward prices/incentives Use Case 4 DER fleet capability forecast Use Case 5 DER fleet flexibility metric Use Case 6 Include DERs in planning models 20

21 transactive exchange direct control device parameters BEq Roles in a TE Architecture Exchange Operation Supervisory Control (HEM, BMS) TE Grid Node TE Edge Node UC-4. DER fleet capability forecast UC-5. DER fleet flexibility metric UC-2. Select grid service(s) for submitted offers UC-3. Optimize response for each grid service BEq Interface Device Control Smart Thermostat Charge Controller Inverter Controller Device Models DER HVAC Battery + Inverter PV Array + Inverter 21