Smart Inverter Testing for Autonomous Grid

Transcription

1 Smart Inverter Testing for Autonomous Grid John Mead, PE Pacific Gas and Electric Company Applied Technology Services, San Ramon READ AND DELETE For best results with this template, use PowerPoint

2 What is a Smart Inverter? A Smart Inverter is an inverter system with additional features beyond current utility interconnection requirements. The CPUC and CEC have jointly formed the Smart Inverter Working Group (SIWG) to identify technical changes to Rule 21 for Smart Inverters. SIWG has defined the smart inverter features recommended for adoption by the CPUC: Phase 1 Autonomous Operation (Adopted): 1. Low and High Voltage Ride-Through; 2. Low and High Frequency Ride-Through; 3. Dynamic Volt-VAR Operation; 4. Ramp Rates; 5. Fixed Power Factor; 6. Soft Start Reconnection; 7. Anti-Islanding Protection to reflect proposed new voltage ride-through settings; Phase 2 Communications Standards (Road Mapped) Phase 3 Advanced Functionalities some of which use Phase 2 Communications Standards (Road Mapped) 1. Watt-Frequency 2. Watt-Volt 3. Limit Real Power UL (UL 1741 SA Draft) and IEEE (1547) are working on updating standards for Smart Inverters 2

3 Smart Inverter Laboratory Testing: Laboratory Testing Effort Driven by two projects: Smart Grid Volt/VAR Project (primary) Examine interrelation between VVO and SI EPIC 2.3 Smart Inverter Project Examine both autonomous functionalities and communications methods. Single-unit Testing: Lab testing performed at the ATS facility will evaluate basic SI functionalities on a component (individual inverter) level under normal and abnormal conditions. Group Testing: Beyond those basic SI functions testing, a group use of autonomous functions of SI in close electric proximity to each other will be evaluated more qualitatively. 3

4 Volt/VAR with Smart Inverters: It s all happening on the secondary Secondary is isolated by service transformer System Primary Transformer Secondary Transformer between primary and secondary by far the largest impedance Load Two things determine how much voltage regulation is possible from a smart inverter: size of the inverter and system impedance The Secondary is very noisy 4

5 Smart Inverter Test Setup The smart inverter test setup will simulate a full power secondary residential system. Design Requirements: Secondary cabling impedance included 120/240V Single Phase Simulator Bi-direction power (both real and reactive) Frequency and voltage control Simulated variable system source impedance via RTDS interface Five Major Subsystems: 1. Grid Simulator 2. Load Module 3. SI System 4. Test Setup Monitoring and Control System 5. Communication Infrastructure 5

6 Smart Inverter Test Setup Grid Simulator Simulation of the distribution transformer and the system impedance is achieved using a bidirectional power amplifier in combination with a high-speed real-time digital computer. This Grid Simulator is capable of varying voltage and frequency and capable of simulating various system source impedances RTDS Grid Simulator RTDS receives frequency and RMS values from LabVIEW 6

7 Smart Inverter Test Setup Load Module Load Module need to be able to simulate a load of typical residential home: DAS crio To Rack Inverters Smart Meter To Secondary wiring/ Grid Simulator Load Center Inductors Chroma Programmable Loads Design Requirements: A residence is two 19 racks crio provides localized monitoring and control. Programmable Loads permits fast dynamic load response 3 sets of inductors for reactive loads (1kVAR each) 7

8 Smart Inverter Test Setup Smart Inverter System String Smart Inverters can be installed in any of the 20 racks, micro inverter are fixed in 4 racks: Variability of Solar Irradiance is simulated by changed current limit on DC power supplies String Inverters Power Supplies Aux Bus 208VAC 3ph Analog I/O Smart Inverter System String Inverter PS1-1 Power Supply Sorensen SGA 600/8 5kW 600VDC 8A 1) PS PS1-2 Power Supply Sorensen SGA 600/8 5kW 600VDC 8A 1) PS Smart Inverter System Micro Inverters SI 1-1 Smart Inverter 5kW 550VDC/240VDC SI 1-2 Smart Inverter 5kW 550VDC/240VDC Optional 100 Cable Inverter wire impedance Load Center Micro Inverters Aux Bus 480VAC 3ph PS1-1 Power Supply Xantrex kW 60VDC 100A 2) PS SI 1-1 SI 1-14 SI 1-1 to SI 1-14 Smart Inverters 14 x 280W 37V (Total 3.92kW) SI 1-2 SI 1-13 SI 1-3 SI 1-12 SI 1-4 SI 1-11 SI 1-5 SI 1-10 SI 1-6 SI 1-9 SI 1-7 SI 1-8 Inverter wire impedance Power Supplies PS1-2 Power Supply Xantrex kW 60VDC 100A 2) PS SI 1-15 SI 1-15 to SI 1-28 Smart Inverters 14 x 280W 37V (Total 3.92kW) SI 1-16 SI 1-17 SI 1-18 SI 1-19 SI 1-20 SI 1-21 Load Center Analog I/O SI 1-28 SI 1-27 SI 1-26 SI 1-25 SI 1-24 SI 1-23 SI

9 Smart Inverter Test Setup Test Setup Monitoring and Control System All monitoring/control of the test setup is done using NI system. Design Requirements: Networked distributed system: master PXI with 12 crio LabVIEW GUI interface Scripts can be loaded to automate testing Automated data storage 9

10 Smart Inverter Test Setup Communication Infrastructure Design Requirements: Network to be separate from both UDN and ODN to permit evaluation of non-standard communications systems (TICNET). RTAC DNP3 to Modus translator SSN capable to try Smart Meter interconnections. Wifi and Zigbee also possible 10

11 Preliminary Test Results: Throttling Example: String inverter with step change in power level 11

12 Preliminary Test Results: PF Example: Micro-inverter given step change in PF level 12

13 Questions? 13