Emhemed, Abdullah and Burt, Graeme (2015) LVDC

27 Pages·2017·2.86 MB·English

LVDC-Redefining Electricity
New Delhi, India,
First International Conference on Low Voltage Direct Current 26 & 27 October 2015
International Bureau of
Electrotechnical Indian Standards
Commission
Enabling an LVDC last mile
distribution network
Dr Abdullah Emhemed
Prof Graeme Burt
University of Strathclyde
Department of Electronic and Electrical Engineering
Technology and Innovation Centre
[email protected]
Tel: [phone]
Glasgow-United Kingdom
Overview
Issues with an existing LVAC last mile network
1.
Moving to an LVDC last mile: motivations
2.
Moving to an LVDC last mile: challenges
3.
Protection challenges
4.
Protection solution
5.
Conclusions
6.
1. Issues with existing LVAC last mile
Under pressure
to host more
renewables
Requires AC-DC conversion
Operates at 60
for supplying DC loads and
-70% of their
hosting renewable
limits with
losses 3%
y 11/0.4kV
l
p
Distribution p
u
networks are S
NOP

V
aging
M
Benefit the Under pressure to
least from host more heat and
load diversity transport demand
Become a bottleneck to connect
further EV and heat pumps, power
flow could reach up to 130%-150%
in future UK system
http://corrupteddevelopment.com/
2. LVDC last mile: motivation
Potential benefits for DSOs
Existing MV network
11kV/0.4kV
Suitable and powerful ICT platform
Reduced losses and increased power capacity
for integrating various smart grid
functionalities
Better control of peak demands
Unipolar
Supporting better controls,
Addressing the technical constraints or bipolar
cable and easier to connect multiple
(enhanced voltage profile, limited impact
connections
sources
of the inductance, no skin effect, etc.)
Load
Release additional generation and
No phase balance and
demand headroom, and defers
variable synchronisation issues
reinforcement
speed ac
source
Load
Reduced fault level and allow the
flexibility in operation offers more flexible
use of lower current ratings and
market mechanism with better
smaller footprint
stimulation of customers control demands
2. LVDC last mile: motivation
Potential benefits for DSOs
Selected projects of DC in distribution
ScottishPower £15m ANGLE – DC project
KEPCO aims to replace a number of existing
AC rural MV distribution networks supplying
light loads by LVDC networks to save up to
5% of the total operating cost
P. Muutinenet al. “Experiences from use of an LVDC system in public
Real rural LVDC network as a part of Finnish electricity distribution” CIRED 2013
national Smart Grids research programme
2. LVDC last mile: motivation
Potential benefits for end-users
Existing MV network
11kV/0.4kV
Reduced energy waste and losses by Power converter interfaces are
reducing AC-DC conversion stages more mature and their
associated costs are declining
Unipolar
or bipolar
Better control of energy leads to cable
connections
better market services and consumers
cost savings
Load
variable
speed ac
More suitable for devices
source
Load
generate and consume DC
(80% of todays load are DC)
2. LVDC last mile: motivation
IET LVDC Code of Practice
Section 4: Recognised standards of d.c. power distribution over
telecommunications cabling
Section 5: Proprietary d.c. power distribution over
telecommunications cabling
Section 6: Proprietary d.c. power distribution over proprietary cabling
Section 7: Proprietary d.c. power distribution over conventional single
phase a.c. power supply cabling
Section 8: Proprietary d.c. power distribution over conventional 3-
phase a.c. power supply cabling
If we are designing the first last mile today,
would be an AC or DC?
3. LVDC last mile: challenges
Very limited experience
Huge investment in AC
Interaction with existing AC grid
Lack of standards (topology, voltages, cable
connections, etc.)
international systematic approach on LVDC not yet
provided
LVDC benefits versus the cost
Existing LV protection is too simple and not capable of
enabling the potential benefits afforded by LVDC last
mile networks