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

10.
DC bus signalingVoltage droop control
Grid converter Batteries
Renewable
sources
∆𝑉
∆𝐼 ∆𝐼 ∆𝐼

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

12.
Studied DC nanogrid
Blackbox polytopic model
Droop control
Droop control
Double control loop
with current limitation
Droop
Current sharing

13.
Studied DC nanogrid
Blackbox polytopic model
Droop control
Droop control
Double control loop
with current limitation
Operation mode change
Load disconnection

14.
Studied DC nanogrid
Blackbox polytopic model
Droop control
Droop control
Double control loop
with current limitation
Voltage restoration