SunSpec Inverter Controls Model SunSpec Alliance Members’ Meeting Jan 2012

1. SunSpec Inverter Controls ModelSunSpec Alliance Members’ Meeting Jan 2012

2. Inverter Controls Model • Defines a model for support of programmed, scheduled and autonomous inverter control operations. • New inverter control modes to be optional on a feature basis, via a set of new SunSpec Device Identifiers (DIDs). • Allows the inverter to offer a set of capabilities to clients and for those clients to discover the capabilities of the inverter and to skip function blocks it does not recognize or implement. • Applies to PV inverters, with or without battery storage. • Based on past and on-going work in various industry and standards bodies, including IEC TC57/WG17, DNP3 User’s Group and EPRI. • Aligns with IEC draft 61850-90-7 and EPRI draft 1023059.

3. Current Inverter Model • Basic inverter measurements and status; no control operations. • Two maps defined: integer with scale factors and floating point without scale factors. Unique DID for each map. • Inverter model map elements: • AC current and voltages (all phases) and scale factors • AC power, AC frequency, AC VA, AC VAR, AC PF, AC Energy • DC current, voltage, power and scale factors • Temperatures (4) and scale factor • SunSpec status (enumeration), vendor defined status • SunSpec event flags (64 bits), vendor defined event flags (128 bits)

4. Inverter Controls Model Overview • Nameplate Ratings • Basic Settings • Extended Measurements and Status • Controls • Immediate Controls • Basic Storage • Pricing Signal • Static Volt-VAR Arrays • Frequency-Watt Curve • Dynamic Reactive Current • LVRT/HVRT Arrays • Watt-PF • Voltage-Watt • Basic Scheduling

5. Chained Control Blocks with Defined Device IDs

6. Nameplate Ratings • Read-only values set by inverter manufacturer • Inverter Ratings (Watt, VA, VAR) • Storage Ratings (Amps, Ahr, Whr, Max Charge Rate, Max Disch. Rate • Required if any controls blocks are used

7. Basic Settings • Operating limits and reference values used in control functions • WMax, PRef, VMin, VMax, VAMax, VarMax, VRef, VRefOfs • MaxWLimPct, ECPNomHz • Default ramp rates • MaxRmpRte • Measurement/setting meanings • PFSign, VarAct, ClcTotVA, ConnectedPhase • Required if any controls blocks are used

8. Extended Measurements/Status • Inverter present/available • Storage present/available • ECP connection status • Real energy (64-bits) • Apparent energy (64-bits) • Reactive energy by quadrant (64-bits each) • Available VARs • Time source and current time • Required if any controls blocks are used

9. Immediate Controls • Connect/disconnect from grid • Max power output [curtailment] (% WMax) • Fixed PF (cos(ϕ) + excitation) • Fix VAR (% VarMax) • Plus random time window, reversion time, ramp time

10. Basic Storage • Setpoints for max charge, max charging VA • Set maximum charge/discharge gradients • Set minimum reserve storage (% max storage) • Status/Measurements • Charge state, state of charge, battery voltage, charge status • Set storage control mode (charge/discharge) • Ramp rates • Power output rate, power input rate • Random window, reversion time, ramp time for in/out power rates • Grid charge allowed (yes/no)

11. Pricing Signal • Pricing signal type • Absolute price • Relative price • Price multiplier • Qualitative (high/medium/low) • Pricing signal value • Random window, reversion time, ramp time • Used with built-in pricing knowledge or pricing schedule

12. Static Volt-VAR • Curve-based description of response • Variable number of curves (recommend min 4) • Variable number of points (recommend min 10) • Curves contain points and filter/ramp values • Volt-VAR pairs as %VRef and %VarAval • Low pass filter time (seconds) • Increment and decrement ramps (%VarAval/min) • Number of active points in curve • Random time window, reversion time, ramp time

13. Frequency-Watt • Parameter or curve-based • Parameter method • Watt reduction gradient • Start frequency • Stop frequency • Hysteresis • Curve-based description of response • Variable number of curves (recommend min 4) • Variable number of points (recommend min 10) • Curves contain points and filter/ramp values • Frequency-Watt pairs as Hertz and %PRef • Low pass filter time (seconds) • Increment and decrement ramps (%WMax/min) • Number of active points in curve

14. Dynamic Reactive Current Support • Inject additional reactive current based on change in voltage • Upper/lower zone limits, outside which no additional VARs supplied • Upper/lower delta voltages, below which no additional VAR support • Gradient for additional inductive or capacitive current • Filter time for calculating average voltage • Hysteresis voltage

15. LVRT/HVRT • Curve-base description • Must disconnect curve • Optional must remain connected curve • Variable number of points (recommend min 10) • Curves contain points • Time-Voltage pairs as seconds and %VRef • Min/max service voltage for reconnection • Delay times for reconnection

16. Watt-Power Factor • Curve-based description of response • Single curve (infrequently changed control) • Variable number of points (recommend min 10) • Curve contains points and filter/ramp values • Watt-PF pairs as %WMax and cos(ϕ) plus PF excitation • Low pass filter time (seconds) • Increment and decrement ramps (%PF/min) • Number of active points in curve • Random time window, reversion time, ramp time

17. Volt-Watt • Curve-based description of response • Variable number of curves (recommend min 4) • Variable number of points (recommend min 10) • Curves contain points and filter/ramp values • Volt-Watt pairs as %VRef and %WMax • Low pass filter time (seconds) • Increment and decrement ramps (%WMax/min) • Number of active points in curve • Random time window, reversion time, ramp time

18. Basic Scheduling • Array-based X-Y description of schedule • Variable number of schedules (recommend min 4) • Variable number of entries (recommend min 10) • Variable X meaning (relative time, temperature, price) • Variable Y meaning (%WMax, PF, price, Volt-VAR array, charge/discharge gradient, VarAval) • Schedules contain X-Y values • X value as defined by its meaning • Y value as defined by its meaning • Repetition flag (none, daily, weekly, monthly, weekdays, weekends) • Random time window and ramp time • Number of active entries in schedule

19. Current Status (2/01/12) • Two working documents: Word doc with explanatory text and spreadsheet with Modbus map details. • Working group meeting weekly (8am PST, Wednesdays). • Completed first pass of proposed Modbus map and explanatory document. • Ready for review by an extended technical audience.

20. Questions

21. Bill Randle AE Solar Energy Headquarters 20720 Brinson Blvd Bend, OR. 97701 541.323.4441877.312.3832 bill.randle@aei.com www.advanced-energy.com/solarenergy