Download Reverse Power Flow

Connecting Low Carbon
Generation
Clive Goodman
Primary System Design Engineer
Western Power Distribution
• Wholly owned
subsidiary Pennsylvania
Power & Light ( PPL)
• 4 UK Distribution
Licences incl. former
CN since April 1st 2011
• Serves 7.6 million
homes + businesses
• 55,000 sq km
• Largest length UK
network – roughly 1/3
Renewable Generation
• Wind
• Photovoltaic
• Hydro
• Wave
• Biomass
• Geothermal
• Other?
Growth of Distributed
Generation
• 240% increase in DG connection (2009/10) Ofgem
• Feed-in-Tariffs were introduced on 1 April 2010 &
provide incentives for small-scale generators to to
5MW
What is Driving Distributed
Generation ?
• Environmental Concerns – Greenhouse Gas
Emissions from Fossil Fuels
• Technological Innovation- Wind, Wave, Solar &
Biofuels
• New Government Policy – Secure, Low
Carbon, Competitively Priced
Feed in Tariffs (FITS)
•
•
•
•
Introduced on 1 April 2010
Provide financial incentives for small-scale generators up to 5MW
Most installations are Photovoltaic and Wind
South West & South East accounting for almost 40% of the total
installations
• Total Installed Capacity Breakdown of FIT installations by technology:
81 % Photovoltacic
11% Wind
5% Hydro
3% Anaerobic digestion
Renewable Resource
Small Scale Embedded
Generation (SSEG)
• Low Voltage 230/400V
• Up to and including 16A per phase, single or
multiple phase
• 3.68kW (Single-Phase)
• 11.04kw (Three-Phase)
Small Scale Embedded Generation
Installed PV (West)
12
10
MW
8
6
4
2
0
2007.5
2008
2008.5
2009
2009.5
2010
2010.5
2011
2011.5
Small Scale Embedded Generation
SSEG installed
5000
4500
4000
3500
No.
3000
Wales
2500
West
2000
1500
1000
500
0
PV
Wind
CHP
Hydro
Wales
1448
57
1
8
West
4359
223
10
15
Utilities Act 2000
• It shall be the duty of an electricity
distributor –
(a) To develop and maintain an efficient, coordinated and economical system of
electricity distribution
(b) To facilitate competition in the supply and
generation of electricity
Connection Process
• G83 Stage 1 – Single Installations of SSEG – Legal
Obligation for installers to notify the DNO within 28
days of commissioning
• G83 Stage 2 – Multiple Installations of SSEG (eg.
Housing refurbishment in the same street or New
Housing Development)– Application to the DNO
required + test certification. Application considered
and costs/implications advised
• G59 – Larger applications for generators in excess of
16A per phase (3.68KW)
Electricity Network Challenges
Reverse Power Flow
• Voltage Rise
• Equipment Ratings
Power Quality
• Voltage Disturbances (flicker)
• Voltage Distortion (harmonics)
Fault Levels
• Equipment short circuit ratings
Traditional Network
Power Station
Power
Flow
Transmission System
(400kV and 275kV)
High Voltage
Distribution System
(132kV, 33kV and 11kV)
Industrial & Large
Commercial Loads
Small Commercial Loads
and Domestic Properties
Low Voltage
Distribution System
(400/230V)
Renewable Generation
Power
Flow
Power Station
Transmission System
(400kV and 275kV)
High Voltage
Distribution System
(132kV, 33kV and 11kV)
Reverse
Power
Flow
Wind Farms etc.
Low Voltage
Distribution System
(400/230V)
Small wind turbines, PV systems,
and hydro systems etc.
Voltage Rise Theory
• Assumes lightly loaded
• Voltage rise pu = V1 -Vo
Voltage Rise
Max. Generation & Min. Load
253V
Ohms Law
Max. Load
V=IxR
216.2V
SSEG
SSEG
Transformer
Resistance
SSEG
Resistance
SSEG
Voltage Rise
Solutions:
• Reduce resistance (impedance) of
the network.
• Improve network utilisation (i.e.
ensure we get the most out of the
network)
• Limit the connection of generation
Voltage Rise
Improve Network Utilisation:
• Improve network modelling
• Increase monitoring on the LV network (Smart Meters
and Smart Networks)
• Improve voltage regulation at 132kV and 33kV
substations
• Reduce voltage on HV and LV networks
• Introduce load / generator control
• Introduce automatic voltage regulation on our LV
networks
Power Quality
Voltage Disturbance:
• Sudden increase or reduction in current / power
causing voltage to dip or rise
• Causes flickering lights
Solutions:
• Improve equipment design
• Reduce resistance (impedance) of the network
• Changes in lighting technology may help (e.g.
compact fluorescent lighting)
Power Quality
Voltage Distortion (harmonics):
• Caused by non-linear load / generation (power
electronics, inverters, motor drives, fluorescent
lighting etc.)
• High levels of harmonics can cause capacitors /
power supplies to fail, transformers to overheat,
cables to overheat and metering inaccuracy
Solutions:
• Improve equipment design
• Reduce resistance
(impedance) of the network
Voltage (V)
600
400
200
0
-200
-400
-600
Low Carbon Networks Fund
• £500 Million Funding
• Tier 1 £80 Million for small scales projects across all the DNOs
• Tier 2 £320 Million for ‘Flagship Projects’ where DNOs
compete for funding
• £100 Million discretionary fund
• Accelerate development of Low Carbon Electricity System
• Impact on DNO network performance
• Delivered benefits to customers expected to exceed cost of
project
• Generate new knowledge to be shared
Low Carbon Networks Fund
WPD Projects Include:
• Network Templates Project (monitoring 1000
distribution substations and associated LV network)
• Melin Homes - 20 PV installations (38kW)
• 11kV Voltage Regulation (use of STATCOM systems)
Low Carbon Network Fund
Tier 2 Projects 2011
• FALCON (Western Power Distribution East Midlands)
• Facilitate the installation of low carbon technologies by
avoiding traditional reinforcement
• Use of real time network data in inform network decisions
• Development of a scenario investment model using data from
the trials
• Control network tests in an area with about 200 distribution
and primary substations centred on Milton Keynes
Low Carbon Networks
Tier 2 Projects 2011
• Buildings, Renewables , Integrated Storage To Overcome Limitations
(BRISTOL)
• 30 Houses, 10 Schools and an Office with Solar PV and Battery installation
• Solar PV Battery connected using DC connection
• DC Lighting Circuits + Small appliances run on DC direct from solar PV and
battery
• Battery ‘shared’ between Customer and DNO
• Tariff to encourage electricity use at times of high PV generation and use
battery when network is heavily loaded
• Focused on social housing in Bristol in conjunction with Bristol City Council
• Solar PV, Heat Pumps & Electric Vehicles require network reinforcement –
Project will provide data on how the existing capacity may be better
utilised
The End