Modelling DC smart nanogrids for local power distribution
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This document discusses the vision and challenges of implementing smart grids with hierarchical DC-based microgrids. It describes a potential architecture with nanogrids and picogrids powered by a 380V DC main distribution bus. Key challenges discussed include the need for standardized DC voltage levels, reliable DC circuit breakers and buses, and distributed control schemes like droop control. Modeling and control of the complex nonlinear converter systems is also highlighted as an important area of further research.
Modelling DC smart nanogrids for local power distribution
- 1. European cooperation Network on Energy Transition in Electricity Roberto Prieto CEI UPM - Center for Industrial Electronics of UPM SESSION 2: SMART GRIDS CHALLENGES: THE VISION OF TECHNOLOGICAL CENTRES WORKSHOP “DEFINING SMART GRIDS: CONDITIONS FOR SUCCESSFUL IMPLEMENTATION” Barcelona, 9th February 2017
- 2. ▪ Hierarchical architecture ▪ Power converters as interfaces ¢ Energy Control Center (ECC) ¢ Individual power supplies ¢ Bus providers ▪ Distributed generation ¢ Renewable sources ¢ Traditional generators ▪ Energy storage systems ▪ Smart Grid Microgrid µ-ECC Utility mains Nanogrid n-ECC Picogrid p-ECC
- 3. ▪ DC native loads and sources ¢ Photovoltaic, batteries, fuel cells… ¢ Consumer electronics, LED lighting ▪ Central power factor corrector ¢ Less conversion stages at device level ¢ No need for AC/DC power adapters ▪ Simpler smaller converter interfaces ¢ No need for synchronization ¢ Less components: no rectification ¢ No need for low frequency bulk capacitors in each power supply
- 4. ▪ DC current disconnection ¢ Reliable DC circuit breakers ¢ Plugs and sockets ▪ Buses and wiring ¢ Lack of reliable standard ¢ How many voltage levels do we need? ▪ Droop control and hierarchical control ¢ Distributed control and communication network ¢ Implementation in converter controller loop ▪ Energy management ¢ Energy storage and distributed generators ¢ Islanding and grid connection ¢ Power converters are essential for energy flows » Image source: Nextek Power Systems & EMerge Alliance
- 5. ▪ 3φ – 380VDC n-ECC ▪ 380V distribution ▪ LVDC room picogrids ¢ Safe voltage level ¢ Limited power ¢ Internal bus ¢ Channel distribution ▪ PHEV picogrid ¢ Smart battery management ▪ Bidirectional converters ¢ Enhanced flexibility n-ECC p-ECC p-ECC Picogrid 2 LVDC Picogrid 1 PHEV Nanogrid 380V Internal bus
- 6. ▪ Main distribution bus – 380 VDC nanogrid ¢ Widely used in datacenters ¢ Low wire losses ¢ Supplies high power equipment and p-ECC ¢ High power distributed generation and bulk energy storage ▪ PHEV bus ¢ Follows PHEV charging standards ¢ High power, medium voltage, short bus ▪ LVDC buses ¢ Voltages yet to be determined ¢ Internal medium voltage bus ¢ Power distribution through extra low voltage, low power independent channels ¢ Consumer electronics, LED lighting, low power generation…
- 7. Design Model Simulation Satisfactory? No Implementation Satisfactory? No Yes Nanogrid Others Control system Power converters ▪ Off the shelf – Internal architecture unknown – Difficult to find models Black-box modelling Ensure stability
- 8. Grid AC/DC DC/DC AC/DC DC/DC DC/AC DC/DC DC/DC DC/DC DC/DC DC/DC DC/DC DC/DC 𝑉"#$ = 380V 𝑉"#$ = 48V 𝑉"#$ = 24V 𝑉"#$ = 12V
- 9. Grid ? ?? ? ? ? ? ? ? ? ?? 𝑉"#$ = 380V 𝑉"#$ = 48V 𝑉"#$ = 24V 𝑉"#$ = 12V
- 11. Lineal • G-parameters model • Lineal or mildy non- lineal systems Wiener- Hammerstein • Non-lineal static behavior • Lineal dynamics Polytopic • Non-lineal systems • Trade-off between accuracy and complexity Black-box modelling Non- Linear static behavior u yInput Lineal dynamic Output Lineal dynamic u y
- 13. Studied DC nanogrid Blackbox polytopic model Droop control Droop control Double control loop with current limitation Operation mode change Load disconnection