Transcript MI Lees UK Alpha 4 – Block 3 Barcelona 12

Barcelona 12-15 May 2003
Practical Measures to increase
Distributed Generation
in existing Distribution Networks
M I Lees
M Barlow
A Collinson
M I Lees UK Alpha 4 – Block 3
EA Technology
Scottish & Southern Energy
EA Technology
1
Barcelona 12-15 May 2003
Environmental Driver vs Economic Impact
• Distributed Generation is driven in UK by
Government Targets:
– To produce 10% of the UK’s energy needs from
renewable sources
– To reach a total of 10GW of CHP generating capacity
(an approximate doubling of current capacity)
• UK Regulator prime responsibility:
– To minimise the economic impact on customers
• Consequently the DGCG is:
– Encouraging innovation in the distribution networks
– “Active Network Management” replacing “Fit & Forget”
M I Lees UK Alpha 4 – Block 3
2
Barcelona 12-15 May 2003
Not starting with a “Green Field”
• Transition is to be evolutionary not revolutionary
• First step is application of
“Basic Active Network Management”
Increasing the degree of network and / or
generation management to increase:
• the amount of generation plant
connected to distribution networks
• the amount of energy generated from
new and existing plant
M I Lees UK Alpha 4 – Block 3
3
Barcelona 12-15 May 2003
Short-Term Solutions
•
Project in Workstream 3 of the Technical Programme of
UK DTI / OFGEM sponsored Distributed Generation
Coordination Group
•
Full report will be available at:
www.distributed-generation.gov.uk
•
Two potential rollout strategies for the solutions:
1. Issues readily addressed: establish “good practice” that
can be adopted by all the DNOs.
2. Issues not fully understood: recommendations for
further study to better quantify the risks & reduce the
uncertainty.
M I Lees UK Alpha 4 – Block 3
4
Barcelona 12-15 May 2003
Project Methodology
• Identify possible Short-Term Solutions
• Assess against 50 defined criteria:
– Implications for customers
– Implications for distributed generators
– Implications for distribution network operators
• Establish the appropriate rollout strategy
• Aim to establish how far “good” engineering
practice had evolved to “Best Practice”
• Establish indicative costs to benchmark against
network enhancement and reinforcement.
M I Lees UK Alpha 4 – Block 3
5
Barcelona 12-15 May 2003
Short-term solutions for
Fault Level Management
Roll-out
Strategy
Cost
Up-rate network (eg. replace switchgear)
1
Low (per unit)
Increase impedance of components
1
High
Converter technology for wind turbines
1
High
Converter technology for other generator types
Long-term
Unknown
Network reconfiguration (moving split points)
1
Low
Network reconfiguration (network splitting)
2
Low CAPEX
OPEX?
Is Limiter
2
Low
Sequential switching
2
Medium
Fault level management procedures
1
Low
Active fault level management
Long-term
Unknown
e.g. re-configuration of the network based on actual generator
presence and calculated fault levels
M I Lees UK Alpha 4 – Block 3
6
Barcelona 12-15 May 2003
Short-term solutions for
Voltage Control
Rollout
Scenario
Cost
Line re-conductoring
1
Low
Build a dedicated line or network
1
High
Generator reactive power control
1
Low CAPEX
OPEX?
Generator real power control
1
Low CAPEX
OPEX?
Line voltage regulation e.g. a single regulator on a circuit 1
Medium
Cancellation CTs
1
Low
Virtual VT
1
Low
Active voltage control
eg remote voltage sensing associated with a single
generator
2
Medium
M I Lees UK Alpha 4 – Block 3
7
Barcelona 12-15 May 2003
Short-term solutions for
Power Flow Management
Roll-out
Strategy
Cost
Line re-conductoring
1
Low
Build a dedicated line or network
1
High
Pre-fault Constraint
1
Low
Post-fault Constraint – single generator
(intertripping)
1
Medium
Post-fault Constraint – multiple generators
(intertripping)
2
Medium
Post-fault Constraint – single generator
(dynamic, including use of short-term ratings)
1
Low / Medium
Post-fault Constraint – multiple generators
(dynamic, including use of short-term ratings)
2
M I Lees UK Alpha 4 – Block 3
Dep. on SCADA
Unknown
8
Barcelona 12-15 May 2003
Two Examples
• Progressive control of Power Flow
• Fault Level:
– Device is Available
– Safety Concerns are delaying wide scale use
M I Lees UK Alpha 4 – Block 3
9
Barcelona 12-15 May 2003
Conventional network design methodology
• Generator output
restricted to
“firm capacity”
33kV Busbar
33kV feeder
• 12MVA
33kV feeder
12MVA (max)
33/11kV
12MVA
33/11kV
12MVA
11kV Busbar
1-4MVA (summer)
2-6MVA (winter)
1-4MVA (summer)
2-6MVA (winter)
Load
M I Lees UK Alpha 4 – Block 3
G
Load
0-12MVA
10
Barcelona 12-15 May 2003
Post fault direct intertripping
• Generator
output 24MVA
under normal
conditions
• “Post Fault”
constrained to
12MVA
• Generator trips
if any upstream
breaker trips
33kV Busbar
33kV feeder
33kV feeder
33/11kV Primary Substation
33/11kV
12MVA
33/11kV
12MVA
11kV Busbar
Intertrip
System
Trip
Load
1-6MVA
M I Lees UK Alpha 4 – Block 3
Load
G
1-6MVA
11
Barcelona 12-15 May 2003
Power Flow Measurements
• Generator output
24MVA under
normal conditions
• “Post Fault”
constrained to
12MVA
• Measure net
export of power
33kV Busbar
33kV feeder
33kV feeder
33/11kV Primary Substation
33/11kV
12MVA
33/11kV
12MVA
Power Flow
Measurement
11kV Busbar
Generator trip
control
• Only trip if
network capacity
is exceeded
Trip
Load
1-6MVA
M I Lees UK Alpha 4 – Block 3
Load
G
1-6MVA
12
Barcelona 12-15 May 2003
Generator Power Output Control
• Take into account
short term ratings
and loads
• Directly control
generator output
to within network
capacity
• Only trip if
network capacity
is exceeded
33kV Busbar
33kV feeder
33kV feeder
33/11kV Primary Substation
33/11kV
12MVA
Short-term
Plant Ratings
33/11kV
12MVA
Power Flow
Monitor
11kV Busbar
Intertrip
Backup
Trip
Load
1-6MVA
M I Lees UK Alpha 4 – Block 3
Load
G
Generator
Power
Controller
1-6MVA
13
Barcelona 12-15 May 2003
IS Limiter
•
senses rapid rise in fault current
•
fires a pyrotechnic charge to
open the main current path
•
current is limited and then cleared
by a parallel fuse within 10mS
•
There are Safety Concerns:
–
–
–
–
Current-sensing
Fuse
TripT
?rip?
Trigger circuit
Pyrotechnic charge
the IS Limiter is not intrinsically safe (i.e. fail-safe)
the integrity of the triggering supply
the inability to functionally test the equipment
the lack of an associated ‘back up’ system
Is this an opportunity for a Solid State Device?
M I Lees UK Alpha 4 – Block 3
14
Barcelona 12-15 May 2003
Concluding Remarks
• Solutions have been identified which
existing networks can accommodate now
eg.
–
–
–
–
–
–
increasing impedances of components (transformers,
generators and inserting reactors)
converter technologies for wind turbine generators
generator real/reactive power control
line voltage regulation
cancellation Current Transformers
post fault constraints (intertripping and generator
power reduction)
M I Lees UK Alpha 4 – Block 3
15
Barcelona 12-15 May 2003
Concluding Remarks
• Some solutions require further work in order
to address quality of supply or safety issues:
–
–
–
–
–
area-based voltage control
the use of the IS limiter
the application of sequential switching
the introduction of “split network” configurations
post fault constraints for multiple generators
• Full details are given in the Workstream 3
report
M I Lees UK Alpha 4 – Block 3
16
Barcelona 12-15 May 2003
ea technology
World leaders in power asset management solutions
M I Lees UK Alpha 4 – Block 3
17