2012. UK Power Networks. All rights reserved

Demonstrating the benefits of energy storage on an 11 kV Distribution Network

Matthieu Michel –

Technology Innovation and Co-ordination Manager

2012. UK Power Networks. All rights reserved

• Validate the capabilities of a Li-ion Energy Storage System (ESS)

• Demonstrate load-shifting and other interventions within the limits of the device

200 kW, 1 hour discharge duration

600 kW, short durations

• Evaluate the network benefits: accommodate additional demand and generation

• Understand the potential lifetime of the device

• Presentation:

Early results from Operation of the device

Key considerations: Efficiency, Losses, cost of energy

Real power Reactive power

Power rating Finite (nom 200 kW) Finite (nom 600 kVAr)

Duration Finite (nom 1hr) Unlimited

Project Objectives:

2012. UK Power Networks. All rights reserved

Progress Highlights:

• The storage device has operated as a STATCOM since commissioning (April 2011)

• Exchanges of real power have started (May 2012)

• Network diagram

MarthamPrimary

OrmesbyPrimary

Hemsby(Energy Storage System)

Wind farm (10 turbines)

2.25MW

Site where

Additional

monitoring is

being installed

2012. UK Power Networks. All rights reserved

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

10.6

10.7

10.8

10.9

11

11.1

18-Apr-11 19-Apr-11 20-Apr-11 21-Apr-11

Reac

tive

Pow

er (M

VAr)

/ W

indf

arm

out

put (

MW

)

Volt

age

(kV)

ESS Volts (kV) [Model] ESS Volts (kV) [Model] ESS_Q (MVAr) [Data] Windfarm (MW)

Operation: STATCOMVoltage at

Hemsby without ESS

(simulated data)

Voltage at Hemsby with ESS (Simulated

using real data)

18/04 19/04 20/04

WindfarmOutput

ESS Reactive Power

Low Voltage triggering ESS to export reactive power

Increase in windfarm output resulting in voltage increase

High Voltage event caused by windfarm output triggering ESS to import reactive power

DEADBAND

11.07

10.85

2012. UK Power Networks. All rights reserved

Operation: STATCOM Settings Change - July 2012

BEFORE SETTING CHANGES

10.96kV ± 0.11kV

AFTER SETTING CHANGES

10.96kV ± 0.08kV

Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8

• Tightened under and over voltage targets from 10.96kV ± 0.11kV, to ±0.08kV

• kVAr exchanged with the network (Number of occurrences) / Voltage band

2012. UK Power Networks. All rights reserved

Operation: Real Power Exchanges - May 2012

Increase in demand due to switching from

Export to Import

Demand increase due to evening

peak

Drop in demand due to export

from ESS

Fluctuations due to Windfarm

output or variation in

demand

2012. UK Power Networks. All rights reserved

Li-ION BATTERIES

SVC LightPOWER

CONVERSION SYSTEM(DC to AC)

1MVA STEP UP TRANSFORMER(2.2kV to 11kV) AND CIRCUIT

BREAKER

AUXILIARIES

Considerations: Round Trip Efficiency and Losses

• The overall round trip efficiency of the installation is quoted to be more than 90%

• Several components will

impact the efficiency and

losses

• 50kW discharge scenario:

49.7 kW delivered by batteries

48 kW delivered to network

• Each component is being

assessed individually

49.7 kW

48 kW

2012. UK Power Networks. All rights reserved

£0

£10

£20

£30

£40

£50

£60

£70

£80

£90

Scenario 1: Optimised charge / discharge time

Scenario 2: Example of a worst case charge / discharge time

Impo

rt ch

age

/ Ex

port

reve

nue

(£)

Financial impact of an example daily operation:2 full charges / discharges @ 100kW

Import charge

Export revenue

Considerations: Energy cost and Battery life

• On the current Hemsby tariff

Energy import charges will be higher than

the revenue that can be generated from

exporting a similar amount of energy

• Battery life will depend on:

Number of cycles

Depth of discharges

• 1 x daily cycle @ 80% depth of discharge: 10 years

1 x daily cycle @ 40% depth of discharge: 20 years

• The impact of each mode of operation on the battery life will be considered

Hemsby import charge

Export revenue

(80% System

Sell price)

Optimised Worst case

80% / 3,000 Cycles

40% / 10,000 Cycles

2012. UK Power Networks. All rights reserved

Management of Peak power flows

Management of voltages across feeders

Reduce reverse power flows

Improve Power factor

Management of Peak power flows

Management of voltages across feeders

Reduce reverse power flows

Improve Power factor

Switching between feedersSwitching between feeders

Next steps: Device Operations

Control mode

2:

On-site

Manual

Control mode

3:Remote

operations

Management of peak power flows – Time of dayManagement of peak power flows – Time of day

Voltage stabilisationVoltage stabilisation

Voltage stabilisation (different set points)Voltage stabilisation (different set points)

July 12May 12 Jan 13 Oct 13

Benefit demonstration started

Control mode

1:

No

intervention

Control mode 4:Algorithmic control

based on real time network measurements and wind farm

output

Now

Benefit to be demonstrated

Apr 11

Combine Voltage stabilisation + Real power exchangesCombine Voltage stabilisation + Real power exchanges

2012. UK Power Networks. All rights reserved

Conclusions:• The storage device is performing as expected: Reduce voltage fluctuations and manage

power flows

• The early stages of the project have been challenging:

Energy contract, IT connections, troubleshooting issues following commissioning.

• Submitted request for extension: October 2013

• More work is to be done but there is learning to be shared: Early learning report published.

Copies available at the UK Power Networks

stand