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LV Distribution Networks CharacteristicsFor Power Electronics Devices

Peter Lang

Agenda

• Describing distribution networks

• Describe our original functional specification

• Some measurements

• Lessons learned

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UK Power Networks

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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

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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

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LV Distribution board

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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.

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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

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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

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LV busbar voltages

Transformer Demands

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Voltage disturbance ride through

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Audible Noise (pavement SOP)

Background levels (SOP off) About 5 metres from SOP

Average sound level - 62dBA/72dBC

PE switching

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Audible Noise (Inside substation)

Unit switched off inside substation Unit switched On

100Hz from transformer

PE switching

Average sound level 72dBA/88dBC

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EMC and EMF

Radiated emissions Cannon Place EMF measurements Cannon Place

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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

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