Virtual inertia with PV inverters using DC-link capacitors Eberhard - - PowerPoint PPT Presentation

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Virtual inertia with PV inverters using DC-link capacitors Eberhard - - PowerPoint PPT Presentation

Jul 13, 2023 112 likes •309 views

Virtual inertia with PV inverters using DC-link capacitors Eberhard Waffenschmidt, Ron S.Y. Hui EPE/ECCE 2016, Karlsruhe, Germany 5.-9.Sept. 2016 Acknowledgements to : Daniel Wagner, Markus Korbmacher, Bente Muhr, Sonny Glesmann and Nora

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Virtual inertia with PV inverters using DC-link capacitors

Eberhard Waffenschmidt, Ron S.Y. Hui

EPE/ECCE 2016, Karlsruhe, Germany 5.-9.Sept. 2016

Acknowledgements to: Daniel Wagner, Markus Korbmacher, Bente Muhr, Sonny Glesmann and Nora Kovacs.

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Sometimes 85% RE in the grid

Grafic: agora-energiewende

80 60 40 20 0:00 4:00 8:00 12:00 16:00 20:00 Time t / h Power P / GW Conventional Power Solar Biomass Hydro Wind Export Consumption 9.May 2016

85%

  • f the comsumption

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Conventional generators will be missing

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PV panel MPP tracker Mains inverter Power grid DC link capacitor

Topology for virtual inertia

P(f)

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Worst case and size

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Required Energy

Contribution of Germany to Instantaneous Control:

 Energy:

3700 MWs

 Power:

372 MW

With feed in of 80 GW:

 Power:

5W / kW

 Energy:  50Ws / kW

5 10 25 20 Time t/s

  • 0.5
  • 1.0
  • 1.5
  • 2.0
  • 2.5
  • 3.0

Instantaneous Power P/GW Szenario I Few renewables Germany 2033 Ekin = 1.93 MWh ENTSO-E 2033 Ekin = 7.4 MWh Germany 2011

dena-Studie Systemdienstleistungen 2030

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Size of electrolytic capacitors

0.01 0.1 1 10 100 1000 0.001 0.01 0.1 1 10 100 1000 Capacitor volume V / cm³ Energy content E / J

500V 450V 400V 200V 63V 16V Fit

Rated Capacitor Voltage

Fit: V/[cm³] = 3.5.(E/[J])0.72

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Needed capacitor size for 1kW

 50J

 100% voltage ripple

 300J  10% voltage ripple 

 e.g. 3500µF, 400V

 200 cm³

 e.g. 5cm x 10cm

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Daily operation

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∆U c(t)= 1 C

⋅

∫

P0⋅ T a U 0

⋅ d

dt ∆ f f 0 dt

Intermediate solution:

Voltage varitions during daily operation

∆ P P0 =T a

⋅ d

dt ∆ f f ∆ P=∆ I

⋅ U 0

∆U c(t)= 1 C

⋅

∫ ∆ I (t)dt

Definition of time constant Ta: Power into the capacitor: Dependence of voltage and current:

E0=1 2

⋅ C ⋅ U 0

2

  • Max. energy content
  • f capacitor:

∆U c(t) U 0 =T a⋅ 1 2

⋅

P0 E0

⋅ ∆ f

f

Solution:

Voltage variation at the capacitor is proportional to the frequency variation

P = Power step P0 = Power in the grid f = Frequency variatrion f = Grid frequency C = Capacity of the capacitor I = Current into the capacitor U0 = Intermediate voltage Uc = Voltage variation at capacitor

∆U c(t) U 0

∝

∆ f f

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  • 0.4%
  • 0.3%
  • 0.2%
  • 0.1%

0.0% 0.1% 0.2%

  • 0.2%
  • 0.1%

0.0% 0.1% 0.2% 0.3% 0.4% 600 1200 1800 2400 3000 3600 Relative Power Deviation P/Po Relative Frequency Deviation f / fo Time t / s

Df/fo Df/fo filtered DP/Po

14.8.2015, 14:00h-15:00h

Power variation

Power variation: ~ +/-0,1%

  • f rated

power

No significant impact on components

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  • 8%
  • 6%
  • 4%
  • 2%

0% 2% 4%

  • 0.2%
  • 0.1%

0.0% 0.1% 0.2% 0.3% 0.4% 600 1200 1800 2400 3000 3600 Voltage Deviation Uc/Uo Frequency Deviation f / fo Time t / s

Df/fo Df/fo filtered DUc/Uo 14.8.2015, 14:00h-15:00h

Variation of intermediate voltage

Voltage variation: ~ +/-3.5%

  • f nominal voltage

No significant impact on power stage

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Control approach

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Idea of the control

Control keeps intermediate voltage at reference level Modify reference value according to grid frequency

Figure based on: Texas Instruments,

"Digitally Controlled Solar Micro Inverter using C2000 Piccolo Microcontroller", TMS320C2000™ Systems 2 Applications Collateral, 2014

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Realized test circuit with PFC controller

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Figure based on: Infineon,

"Boost Controller TDA4863 - Power Factor Controller IC for High Power Factor and Low THD", Datasheet, Rev. 2, Feb. 2005.

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Measurements: Artificial frequency signal

  • 60
  • 40
  • 20

20 40 60 80 100 120 140 160 50 100 150 200 250 300 350 400 450 500 550 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Power / W Voltages / V

Time t / s

Intermediate Voltage Control voltage (x10) Input Power Ideal Power

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Conclusion

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Virtual inertia with power inverters Use intermediate voltage capacitor:

 Existing hardware can be used  Control easily adapted

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Contact

  • Prof. Dr. Eberhard Waffenschmidt

Electrical Grids, CIRE - Cologne Institute for Renewable Energy Betzdorferstraße 2, Room ZO 9-19 50679 Cologne, Germany

  • Tel. +49 221 8275 2020

eberhard.waffenschmidt@th-koeln.de https://www.fh-koeln.de/personen/eberhard.waffenschmidt/

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