1 LV Distribution Networks Characteristics For Power Electronics Devices Peter Lang
1
LV Distribution Networks CharacteristicsFor Power Electronics Devices
Peter Lang
Agenda
• Describing distribution networks
• Describe our original functional specification
• Some measurements
• Lessons learned
2
UK Power Networks
3
Measure% of
industry
Meter points 8.2 m 28%
Population served 20 m 30%
New connections 130,768 35%
Distributed
generation connected7.6 GW 25%
ED1 totex allowance
(2012/13 prices)£6,029 m 25%
Energy distributed 84.8 TWh 28%
Peak demand 16 GW N/A
Service area 29,250 km2 12%
Underground network 139,000 km 29%
Overhead network 46,500 km 15%
Customer density 44 per km N/A
4
400 kV and
275 kV
400 kV/275 kV > 132 kV
132 kV 33 kV11 kV
33 kV
Industrial
Supplies
11 kV Industrial &
Commercial
Supplies
LV Supplies to
domestic
& small commercial
400 V/230 VSecondary
Substation
Primary
Substation
33 kV > 11 kV 11 kV > LV
Grid
Substation
132 kV > 33 kV
Grid Supply
Points
EHV HV LV
The UK Electricity Supply Chain
~2000M
W
2MW 5kW 4kW
Distribution
Network
Operator
5
LV Distribution board
6
FUN-LV Trial Objectives
• To demonstrate that power electronics in the form of a soft open point can deliver capacity sharing between secondary substations.
• To demonstrate other functions such as voltage and reactive power support, phase unbalance and power factor improvement.
• Understand the reliability of power electronics connected to a distribution network.
7
Electricity Distribution in the 21st Century
Why Smart Grid?
• UK has an ageing Transmission & Distribution network• De-carbonisation of transport set to increase our demand for Electricity• Energy Supply is changing, becoming less controllable• Energy Efficiency driving a proliferation of non-linear loads
Why Consider Power Electronics?
Multi-Function solutions are possible to deliver numerous benefits and maximise the capacity of our existing assets
8
Our original functional specification
Characteristic Value
Low voltage connection 230 V +10% and -6% phase to neutral
Neutral connection Solidly earthed
Number of phases Three phases typically unbalanced
Maximum short circuit fault level 46 kA for 0.5 seconds, 35.1kA for 3 seconds
Target fault clearance time 350 ms
Power factor Between 0.7 lagging, unity and 0.7 leading power factor.
Altitude Below 1000 m
Frequency 49.5 to 50.5 Hz
Emergency condition limits 47.5 to 52 Hz for one minute
Audible Noise 56 dB(A) at 3 m. Measured as per IEC 60076-10:2005
Total Harmonic Distortion (THD) THD levels measured on the LV network are compliant
with ER G5/4-1
9
LV busbar voltages
Transformer Demands
10
Voltage disturbance ride through
11
12
Audible Noise (pavement SOP)
Background levels (SOP off) About 5 metres from SOP
Average sound level - 62dBA/72dBC
PE switching
13
Audible Noise (Inside substation)
Unit switched off inside substation Unit switched On
100Hz from transformer
PE switching
Average sound level 72dBA/88dBC
14
EMC and EMF
Radiated emissions Cannon Place EMF measurements Cannon Place
15
Example of EMC results
Red SOP onGreen SOP off
Summary of lessons
• Size
• Noise – Close to residential areas.
• Ventilation - avoid hot air loops.
• Security – street furniture
• Site access – crane required
• Other street furniture challenges
16