more pv and wind power with smart meter based voltage control
TRANSCRIPT
More PV and Wind Power with Smart Meter Based Voltage ControlOLOF SAMUELSSON, IEA, LUND UNIVERSITY
Overvoltage from DG
• Low X/R in distribution active power affects voltage• DNO allows DG to raise LV voltage 5%• Case study with Kraftringen with three different LV feeders:
– With symmetric three-phase output, villa-roof-sized PV OK everywhere except in remote rural areas
– With unsymmetric output from DG, network capacity is limited with a factor up to 8 (eight)
• Only symmetric DG output considered in the following
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Voltage Control Challenge
• Stay within upper and lower limits when– DG raises voltage– Load reduces voltage– Transformer tap changer raises or reduces all voltages
• How low is the lowest voltage?
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Voltage reduction at maximum load
Smart Meter-Based Tap Changer Control
• Use voltage reading from smart customer meter– Standards define voltage limits at consumer
• If less than maximum load, substation voltage can be reduced• More room for DG until lower voltage limit is reached
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Voltage reduction at actual load
Local Control of DG unit
• If necessary adjust voltage locally– Draw reactive power – remember loss increase– Curtail (reduce) active power
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Case Study 1 – Simulated MV and LV
• Network data from E.ON– 40 MVA 130/20 kV infeed to 9x20 kV feeders – 1 load,
1 generation, 7 mixed– Residential and some rural LV network
• MV: 38 MW wind power and 16 MW PV, LV: 1 MW PV
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Simulation Results
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Traditional Local DG control Combined control
Case Study 2 – Field Test
• E.ON network– 12 MVA 50/10 kV infeed to 9x10 kV feeders– 0.8 MW WTG on 32 km feeder with 1.1 MW load
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Field Test Results
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5
10
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25
30
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% Curtailed wind power
Trad Central Combined
Field Test Meters
• Meters transmit values every 10 s via GPRS or GSM• Lowest voltage captured with two meters 89 % of time
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Conclusions
• Smart Meters a resource for voltage control– Few key points need monitoring– Asynchronous update of data every 10 s works
• Control scheme can be simultaneously applied to MV and LV– No network data needed– Traditional tap changing controller is used
• DG projects need expected curtailment– Matching between load and generation central– Probability replaces worst case
• More details in Ingmar Leisse, PhD thesis 2013Lund University/Industrial Electrical Engineering and Automation 11