li-wen yip breakout session 4.4 v2
TRANSCRIPT
How we assess new PV connectionsLi-Wen Yip
2015 UK Power Networks. All rights reserved
Context
2008 2009 2010 2011 2012 2013 2014 20150
50
100
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UKPN G83 PV Connections
SPNLPNEPN
Year
Cum
ulati
ve M
W C
onne
cted
2015 UK Power Networks. All rights reserved
Improving how we assess new PV connections
Research(LV network monitoring)
Design assumptions
(derating, diversity, min load, no-load volts, harmonics)
Voltage rise assessment tools
(simple spreadsheet vs spreadsheet tool)
Records of existing generation(G83, FiT registers)
2015 UK Power Networks. All rights reserved
LV network monitoring
Source: “Validation of Photovoltaic (PV) Connection Assessment Tool – Closedown Report” bit.ly/ukpn-pvtool-cdr
Generation CT
Data Logger(1min intervals)
Net Export CT
PV Inverter
Research
2015 UK Power Networks. All rights reserved
Derating: efficiency / insolation
Source: “Validation of Photovoltaic (PV) Connection Assessment Tool – Closedown Report” bit.ly/ukpn-pvtool-cdr
Design Assumptions
Worst case for thermal constraints
Worst case for voltage constraints
SpikeSpike
2015 UK Power Networks. All rights reserved
Diversity: panel orientation
Source: “Validation of Photovoltaic (PV) Connection Assessment Tool – Closedown Report” bit.ly/ukpn-pvtool-cdr
4kW panels and inverter
4kW panels / 3.5kW inverter(flat 6 hour peak)
Design Assumptions
2015 UK Power Networks. All rights reserved
Diversity: panel orientation
Source: “Validation of Photovoltaic (PV) Connection Assessment Tool – Closedown Report” bit.ly/ukpn-pvtool-cdr
Design Assumptions
No diversity despite varying
panel orientations
2015 UK Power Networks. All rights reserved
Derating: on-site consumption
Source: “Residential consumer responsiveness to time-varying pricing: Low Carbon London Learning Lab Report A3”,
Figure 5.29, http://bit.ly/1Lhllf0
Design Assumptions
Minimum load200W
2015 UK Power Networks. All rights reserved
Other Assumptions
Source: “Residential consumer responsiveness to time-varying pricing: Low Carbon London Learning Lab Report A3”,
Figure 5.29, http://bit.ly/1Lhllf0
Design Assumptions
Condition Assumption if unknown
No-load voltage 248V
Unbalance – Urban 1.43 : 1 : 1
Unbalance – Rural 2 : 1 : 1
Harmonics Ignored
2015 UK Power Networks. All rights reserved
Simple Spreadsheet
𝐼= 𝑃√3𝑉
∆𝑉=𝐼𝑍
Voltage rise assessment tools
2015 UK Power Networks. All rights reserved
Spreadsheet Tool – Live DemoVoltage rise assessment tools
EDP 08-0160 Distributed Generation Voltag
2015 UK Power Networks. All rights reserved
FiT vs G83 Registers: ≤4kW
Sources: FiT Installation Register Aug 2015, UKPN G83 Register Oct 2015
Records of existing generation
Missing
Registered in Both
UKPN G83 Register
Ofgem FiT Register(UKPN MPANs)
0 50 100 150 200 250 300 350 400 450
163 MW
205 MW
225 MW
369 MW
Total capacity of ≤4kW installations (MW)
Only 41% have same rating (within 0.1kW)
2015 UK Power Networks. All rights reserved
Conclusions
Derating due to efficiency / insolation
For thermal constraints: possibly yesFor voltage constraints: possibly not
Diversity due to varying panel orientations
Potentially reduced or eliminated because of undersized inverters
Derating due to on-site consumption Allow 200W per customer
Voltage rise assessment tool Ask me for a demonstration / copy
Records of existing generation
G83 is incomplete and inaccurate.DNOs can request Ofgem’s FiT data with full MPANs.
