Advanced controls of PV for microgrid applications

Transcription

1 1 Advanced controls of PV for microgrid applications Paper Number: 14PESGM2590 Vijay Bhavaraju Corporate Research & Technology Eaton Corporation Menomonee Falls, WI

2 2 What is a Microgrid? Diesel Storage North Feeder 12kV Substation B Variety of Sources Critical and noncritical loads Grid connected renewables Stand-by generators Variety of fuel sources to energy surety West 12kV Substation A Feeder South Feeder PV Inverter East Feeder Natural Gas Pipeline Legend Critical Load Normal Load Wind Farm 12kV / 480Vac A healthy distribution system with two substation feeding the loads.

3 What is a Microgrid? Islands formed Due to a Power Outage 3 Diesel Storage North Feeder 12kV Substation B 4 Islands are formed Critical loads need to be powered Non-critical loads can be shed Renewables must ride through Need to maintain voltage and frequency within specs.. West 12kV Substation A Feeder South Feeder PV Inverter East Feeder Natural Gas Pipeline Legend Critical Load Normal Load Wind Farm 12kV / 480Vac

4 IEEE Design, Operation, and Integration of DR Island Systems Example-1: Facility Island

5 IEEE 2030 Evolution of Smart Grid Interoperability AMI = advanced metering infrastructure PEV = plug-in electric vehicle N = other smart grid applications PV Microgrid

6 6 PV Grid-tied Standard Controls Grid-tied PV inverters are designed with the following requirements and controls: FEATURE DYNAMIC VARIATION OF IRRADIATION UTILITY VOLTAGE VARIATION UTILITY LOSS DETECTION GROUNDED UTILITY CONNECTION DIFFERENT UTILITY VOLTAGES GROUND FAULT/LEAKAGE DETECTION AND SHUT DOWN OF INVERTER WEAK GRID CONNECTION FAULT VAR SUPPORT CONTROL FUNCTION MAXIMUM POWER POINT TRACKING FAST PLL TO TRACK THE VOLTAGE ANTI-ISLANDING NEED ISOLATION FOR GROUNDED ARRAYS SUITABLE STEP-UP TRANSFORMER LEAKAGE DETECTION FOR FLOATING ARRAYS AND GFD FOR GROUNDED ARRAYS RAMP RATE LIMITS LVRT

7 IEEE Procedures that Provide Supplemental Support New Features Voltage Regulation 1. Monitoring & Communications 2. Response to EPS Abnormal Conditions 3. Power Quality 4. Coordination with NEC and UL Optimizing Group Behavior of DG 6. Requirements to See Fault Conditions 7. Additional Data Requirements 8. DG Greater than 10 MW (< 20MW) 9. New Issues 1. What should be the MVA rating? 2. Why not MODBUS TCP? 3. Move away from Anti-islanding? 4. Who creates the problem? 5. Should comply but can we UL List? 6. Not an inverter function 7. Who is going to pay for it? 8. SunSpec? IEC 61850? 9. PREPA MTR?

8 Ft. Sill Microgrid Controls via Modbus TCP Our Experience 13.2kV 750kVA 480V Static Switch Protection Relay 70kW PV 30kW PV 2kW Wind ~ ~ Bridge ISO = Smax ~ Cntlr PV Smax Inv Cntlr ~ = ~ = ISO MG Cntlr HMI UDP Chilled Auxiliary Water Pumps Pump Storage Inverter SWEEP 40hp PUMP Pump ~ ES SI Inv SI Contlr Contlr Cntlr = Storage Battery Modbus TCP G1 240kVA 200kW Bridge ISO ISO G2 240kVA 200kW Chiller 300hp Pump 400kW 250/ Power 400kW Battery

9 Ft. Sill Microgrid Controls PV Inverter Operation with Lightly Loaded Generators PV Inverter comes online PV output as negative. Starts oscillating at 10:15 Generator output reflects the PV out Generator output drops Solutions: 1. Slowdown the PV ramp-up and down 2. Disable anti-islanding controls 3. Ensure generators are properly loaded

10 10 PV Grid-tied vs Microgrid-tied Inverters Our Experience 1. Add power curtailment 2. Add reactive power support 3. Remove anti-islanding 4. Expand Utility voltage and frequency set points 5. Manage ramp-up 6. Limit inrush current at grid connect 7. Follow SunSpec or IEC for communication 8. Allow remote control (UL to accept this)

11 Wish List for Applications in Microgrid-1 1. Don t disconnect from Grid but follow the transition to an island 2. Connect to microgrid immediately without waiting for 5 minutes 3. Allow new trip settings in microgrid operation 4. Provide Reactive power support per command 5. Power curtailment per command 6. Ramp up limit with ramp kw/sec setpoint control

12 Wish List for Applications in Microgrid-2 1. Ramp down limit with ramp kw/sec setpoint control 2. Reactive power support per output real power kvar per kw 3. Storage support requirements output 4. Adjustable low voltage ride through limits (v & t) 5. Adjustable high voltage ride-through (v & t) 6. Adjustable DC/AC power ratio (<1.x) 7. Short time higher output if available (P, t)

13 Thank You! 80kW Array at Fort Sill Questions?