Research and Education on Power Electronics for Power Systems Fred - PowerPoint PPT Presentation

Research and Education on Power Electronics for Power Systems Fred Wang fred.wang@utk.edu NSF Workshop on Power Electronics- enabled Operation of Power Systems Chicago, IL October 31, 2019

CURENT at a Glance • CURENT was established in 2011 as a NSF/DOE Engineering Research Center, the first US DOE-NSF ERC and only one with a power system focus • CURENT involves four US institutions with about 26 faculty members and 130 graduate students • UTK is the lead institution with 10 core faculty members in power systems and power electronics (5 each), and >100 graduate students in power systems and power electronics (about half and half) • About 40 industry and government members • Courses 5 undergraduate courses (1 junior level, 4 senior level)  ~15 graduate courses  2

CURENT Vision • A nation-wide transmission grid that is fully monitored and dynamically controlled for high efficiency, high reliability, low cost, better accommodation of renewable sources, full utilization of storage, and responsive load. • A new generation of electric power and energy systems engineering leaders with a global perspective coming from diverse backgrounds. Wide Area Control of Power Grid Power Grid WAMS PMU Measurement FDR HVDC & Monitoring Storage Communication Communication Solar Farm PSS Actuation Responsive Wind FACTS Load Farm Generator 3

CURENT Research Roadmap Year 1~3 Year 4~6 Year 7~10 Generation II Generation III Generation I Reduced interconnected EI, WECC and Fully integrated North American system with Regional grids with >20% renewable ERCOT system, with >50% renewable >50% energy (>80% instantaneous) inverter (wind, solar), and grid architecture to (wind, solar) and balance of other clean based renewable resources (wind, solar) and include HVDC lines energy sources (hydro, gas, nuclear) balance of conventional (hydro, gas, nuclear) System scenarios demonstrating a Grid architecture to include UHV DC lines Grid architecture to include UHV DC super- variety of seasonal and daily connecting with regional multi-terminal DC grid and interconnecting overlay AC grid and operating conditions grids, and increased power flow controllers FACTS devices Sufficient monitoring to provide System scenarios demonstrating complete Controllable loads (converter loads, EV, measurements for full network seasonal and daily operating conditions responsive) and storage for grid support observability and robustness against and associated contingencies, including contingencies, bad topology or Fully monitored at transmission level (PMUs, weather related events on wind and solar measurement data temperature, etc.) and extensive monitoring of Full PMU monitoring at transmission level of distribution system Closed-loop non-local frequency and with some monitoring of loads voltage control using PMU Closed loop control using wide area Fully integrated PMU based closed-loop measurements monitoring across all time scales and frequency, voltage and oscillation damping Renewable energy sources and demonstrating full use of transmission control systems, and adaptive RAS responsive loads to participate in capacity and rights-of-way schemes, including renewables, energy frequency and voltage control storage, and load as resources Automated system restoration from outages 4

Needs, Challenges, and Opportunities for Grid Power Electronics Emerging • High % of renewable energy sources; Energy storage System • Power electronics interfaced loads (often CPL) Needs • New types of grids (e.g. DC, microgrids) Challenges • Converter cost, reliability, size, and grid compliance and needs for • Grid support functions Power • Knowledge on system interactions and coordination Electronics • New power electronics technologies including WBG technologies • New system modeling, analysis, design, and control techniques Opportunities • New advances in communication, control, and data analytics • Education 5

Continuous Variable Series Reactor Full-rated CVSR Prototype DC Controller 6

Benchmark SiC Impact on Grid Power Electronics 7

GaN-Based PV Inverter 180 Si-based 160 32% 140 GaN-based 120 100 Cost ($) 80 Power stage 60 40 20 15 cm 0 Filters Si b dG N b d Thermal Line filter Devices EMI filter 42 cm 8

System Level Benefits of SiC-Based Converter 1MW PV array 200 kW BESS AC bus DC bus 200 kW CHP Medium voltage Grid PCC switch FFT of PCC current 1 kHz 400 kW critical Load 600 kW non-critical Load Configuration of MV microgrid Si-based solution SiC-based solution 9

Grid Emulator Hardware Testbed Real three-phase power Hardware Room flow with inverters DC Bus Short Distance Transmission Generator I Long Distance Transmission Line Emulator emulating various Line Emulator Building generation, load, Rectifier Power Generator II HVDC storage, ac or dc Load I transmission lines Cluster 1 Cluster n +1 Output Inductors Cluster n +2 Actual control, Cluster 2 measurement (CTs, PTs, PMUs) communication, Cluster m Cluster n cyber physical M CTs, PTs FDR, PMU infrastructure C n n n g r o o o r o t t i i l CAN Bus Visualization and Control Room 10

Test Scenario – Inverter-Based HTB System Stability Y B 7 L Y B 7 R Area 1 Area 2 G1 G3 1 6 7 9 10 3 * G V * G V Z ov 1 i 1 ( v 1 ) i 3 ( v 3 ) Z ov 3 clv 3 3 clv 1 1 Stable Stability boundary − + − + Z 1-6 Z 3-10 Unstable Experiment cases i 2 ( v 2 ) i 4 ( v 4 ) Z 6-7 Z 9-10 1100 − + + − Z 2-6 Z 4-10 Z ov 4 Z ov 2 * G V * Current loop bandwidth ω c [Hz] G V 4 2 clv 4 4 clv 2 2 Z 7-9 1000 * * G I G I i 7 ( v 7 ) clc 9 9 clc 7 7 G2 i 9 ( v 9 ) G4 900 Y oc 7 Y oc 9 800 L7 L9 700 600 ω c =200 Hz ω c =1000 Hz 500 Unstable Stable 400 G2: i 2 a [20 A/div] 300 200 L7: i 7 a [20 A/div] 100 G4: i 4 a [20 A/div] 0 0 100 200 300 400 500 600 700 800 900 1000 1100 Voltage-feedforward ω ffv [Hz] L9: i 9 a [20 A/div] [ t : 100 ms/div] 11

Test Scenario – Inverter-Based HTB System Stability 12

Grid Support Function Implementation & Testing in HTB Renewable energy sources working modes implemented Frequency response evaluation Wind Turbine Active Power (p.u.) 0.95 0.9 0.85 Base case with generator 0.8 0.75 MPPT 0.7 MPPT with inertia emulation 0.65 0 2 4 6 8 10 Voltage mode Area Frequency (Hz) Voltage mode with storage 60.2 60 59.8 59.6 59.4 59.2 0 2 4 6 8 10 Time (s) Operation under grid fault 13

Virtual Synchronous Generator (VSG) Control for Renewable Integration Experimental result in HTB two area system Current exceeds limit during fault VSG Output Current w/o Limitation VSG current There could be current excursions during or after a fault 3 Load/Fault current Output Current (p.u.) 2 50A/div 10s/div Stable Stable Unstable 1 Without current limit With limit and control With limit no control 0 -1 Current exceeds limit after fault -2 -3 VSG current 79 79.5 80 80.5 81 81.5 82 82.5 Time (s) Load/Fault current Stable Stable Unstable Without current limit With limit and control With limit no control 14

Power Electronics Interfaced Load Models V mbus , f bus DC/DC Load Remote bus EV bus charger v d , v q i d , i q Detailed PLL EMT model Equivalent TS model Modeling algorithm EV charger active power consumption: EV charger modeling principle in TS simulator 15

Small-signal Stability Analysis and Design of DC Grids 2 L arm 2 R arm ^ i dc 3 3 Simulation results vs model results MMC Model I : no submodule ^ capacitor voltage ^ -G cir V dcref i dc v dc DC impedance models of MMC dynamics 80 60 Magnitude/dB Model II : no circulating current control 40 dynamics 20 L arm R arm i dc 2 L arm 2 R arm C ac 2 2 3 3 u a 0 i a u b 10 0 10 1 10 2 10 3 10 4 6 C sub i b v dc u c N Circuit-based Simualtion i c 200 Model I CPL Model II Proposed Model 2 L arm 2 R arm ^ 100 i dc 3 3 Phase/deg ^ d dc NV Csub 0 ^ Experimental setup v dc ^ D dc Nv Csub -100 10 0 10 1 10 2 10 3 10 4 Proposed model : consider both submodule Frequency/Hz capacitor and circulating current dynamics 16

Smart and Flexible Microgrid with Low-cost Open Source Controller Field Test Location BESS G3 SW14 SW12 SW13 SW15 Load 8 Load 9 Load 10 G4 SW1 SW2 SW3 SW4 SW10 G1 Load 1 Load 2 Load 3 Critical Load SW11 SW6 SW5 Distribution line PV Power electronic converter Load 4 Normally closed switch SW8 Wind SW9 SW7 Normally open switch turbine G2 Load 5 Load 6 Load 7 17

Microgrid Controller HTB Test – Resynchronization Process 18

SiC-based Multifunctional Power Conditioning System (PCS) for Asynchronous Microgrid • Develop asynchronous microgrid PCS module employing Wind Turbine Wind Turbine 10 kV SiC MOSFETs with > 10 kHz equivalent switching Energy Storage PV array PV array System frequency and grid support functions AC bus DC bus • 100 kVA/13.8 kV three-phase four-wire PCS DC/AC converter built and tested at nominal AC output. Microgrid Medium Grid side side Microgrid PCS voltage Grid switchgear switchgear • Grid functions of the PCS, including low/high voltage/frequency ride through, faults, unbalance load support, grid stabilizer, etc., validated in HTB. Loads Backup Generator Active Power Filter CHP 100 kVA/13.8 kV Three-phase PCS converter Three-phase PCS testing at 13.8 kVac 19