Impact resonances-low-voltage-grid
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PQ Forum 2011 proceedings http://www.leonardo-energy.org/power-quality-forum-2011-tue-eindhoven

PQ Forum 2011 proceedings http://www.leonardo-energy.org/power-quality-forum-2011-tue-eindhoven

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  • 1. Minimizing the Impact of Resonances in Low Voltage Grids Peter Heskes January 2011The EOS LT project KTI is funded in part by SenterNovemContentsThe KTI projectGrid impedance, interaction and resonancesImpedance measurementMinimizing the impact of resonances 1
  • 2. The KTI project Part 1: Research on new boundary conditions, social importance, consequences and responsibilities. (TU/e – EES group, Laborelec)Part 2: Research on characteristics and Part 3: Research on and development interactions between the grid and of new power electronics to control the connected appliances and generators quality of the voltage (ECN) (TU/e – EPE group)Structure of the KTI project 2
  • 3. Publications Journal articles [1] P.J.M. Heskes, J.M.A. Myrzik, W.L. Kling, “Impact of Distribution System’s Non-Linear Loads with Constant Power on Grid Voltage”, John Wiley ETEP Journal, in-Press. [2] P.J.M. Heskes, J.M.A. Myrzik, W.L. Kling, “A Harmonic Impedance Measurement System for Reduction of Harmonics in the Electricity Grid”, International Journal of Distributed Energy Resources, vol. 5, no. 4, pp. 315-331, Oct./Dec. 2009. Conference papers [1] P.J.M. Heskes, J.M.A. Myrzik, W.L. Kling, “Ancillary Services for Minimizing the Impact of Resonances in Low Voltage Grids by Power Electronics based Distributed Generators”, IEEE Power Energy Systems General Meeting, Detroit, Michigan, USA, July 24-29, 2011, under review. [2] P.J.M. Heskes, J.M.A. Myrzik, W.L. Kling, “Harmonic Distortion and Oscillatory Voltages and the Role of Negative Impedance”, IEEE Power Energy Systems General Meeting, Minneapolis, USA, July 25-29, 2010. [3] P.J.M. Heskes, J.M.A. Myrzik, W.L. Kling, “Power Electronic Loads with Negative Differential Impedance in a Low Voltage Distribution System”, 20th International Conference on Electricity Distribution, Cired, Prague, 8-11 June 2009. [5] P.J.M. Heskes, J.M.A. Myrzik, W.L. Kling, “Survey of Harmonic Reduction Techniques Applicable as Ancillary Service of Dispersed Generators (DG)”, IEEE Young Researchers Symposium, Technical University of Eindhoven, The Netherlands, February 7-8, 2008. Grid impedance, interaction and resonances 3
  • 4. Interaction Grid Operator Point Of Connection Customer (POC) Supply voltage Draw current at from Interaction POC POC via Grid impedance Requirements for Requirements on quality of voltage loads for quality of (EN 50160) Current (IEC 61000-3-2) 7 31-1-2011InteractionExample of a LV distribution grid, two PCC and one PoC examples are depicted 4
  • 5. Interaction Simplified grid model with a lumped large number of resistive loads and parallel capacitancesInteraction The grid loaded with a non-linear load 5
  • 6. Interaction Added damping resistance in the distribution gridResonancesVPCR = Virtual Parallel Capacitance ReductionVRHD = Virtual Resistive Harmonic Damping VPCR VRHD VPCR + VRHD active active active 6
  • 7. Harmonic impedance measurementHarmonic Impedance Measurement The grid voltage is stronglyInjection Current polluted signal injection Zgrid Line Controlled current source 12V 230V PoC Zload Grid simulator Neutral Injection current for a 50.0Hz grid frequency I V Sampled Data PC with Matlab A/D software conversion Impedance measurement in a laboratory set-up The injection current stimulus 7
  • 8. Harmonic Impedance Measurement Start Measure Voltage Shift Measure Voltage Magnitude Measurement (and Current) Spectrum without frequencies time series StimulusThe system: • estimates free spots in freq. domain Voltage Transformation to No • inject current on free spots Magnitude frequency domain Spectrum • collect voltage / current time series below limit? • does domain transformation Calculate Impedance • calculates the impedance spectrum Inject a Current Spectrum signal to the grid Ancillary services for harmonic reduction 8
  • 9. VPCR and VHRD VPCR = Virtual Parallel Capacitance Reduction VRHD = Virtual Resistive Harmonic Damping The inverter’s basic block diagram with focus on the grid interfacing partTime domain lab experiments Experimental result of vgrid polluted with Laboratory set-up 10% of the 11th harmonic 9
  • 10. Inverter modelTime domain lab experiments + Output filter Grid model model iinv Lout igrid Lgrid Rgrid DC Power H-bridge voltage supply Cout vgrid source model model fundamental with 10% - of 11th harmonic 2 1 H-Bridge driver model iinv (t) 0 Controller model -1 -2 1 1.02 1.04 1.06 1.08 1.1 2 inverter currents 1 Igrid (t) 0 VPCR = off VRHD = off -1 -2 1 1.02 1.04 1.06 1.08 1.1 time (seconds) Experimental result of iinv and igrid without activated ancillary services Inverter modelTime domain lab experiments + Output filter Grid model model iinv Lout igrid Lgrid Rgrid DC Power H-bridge voltage supply Cout vgrid source model model fundamental with 10% - of 11th harmonic 2 1 H-Bridge driver model 0 iinv (t) Controller model -1 -2 1 1.02 1.04 1.06 1.08 1.1 2 inverter currents 1 Igrid (t) 0 VPCR = on VRHD = off -1 -2 1 1.02 1.04 1.06 1.08 1.1 time (seconds) Experimental result of iinv and igrid with activated VPCR 10
  • 11. Inverter modelTime domain lab experiments + Output filter Grid model model iinv Lout igrid Lgrid Rgrid DC Power H-bridge voltage supply Cout vgrid source model model fundamental with 10% - of 11th harmonic 2 1 H-Bridge driver model iinv (t) 0 Controller model -1 -2 1 1.02 1.04 1.06 1.08 1.1 2 inverter currents 1 Igrid (t) 0 VPCR = on VRHD = on -1 -2 1 1.02 1.04 1.06 1.08 1.1 time (seconds) Experimental result of iinv and igrid with activated VPCR and VRHD Large scale model 11
  • 12. Large scale computer simulations with the validated inverter model Goal: estimate the total grid impedance at the LV Busbar 5 streets with 10 inverters each on line 1 A customer 1 customer 2 customer 9 customer 10 10m 10m 10m Cable 50 Al customer 11 customer 12 customer 19 customer 20 10m 10m 10m Cable 50 Al customer 21 customer 22 customer 29 customer 30A 10m 10m 10m Cable 50 Al customer 31 customer 32 customer 39 customer 40 10m 10m 10m Cable 50 Al customer 41 customer 42 customer 49 customer 50 10m 10m 10m Cable 50 Al Cap. load Zhome Single Home connection Inverter 12
  • 13. The ancillary service inverter controls the (50Hz) and the 3 th, 5th, 7th, 9th and 11th harmonic. 3 5 7 9 11 Inverter’s controller block with resonators on the fundamental (50Hz) and the 3th, 5th, 7th, 9th and 11th harmonic.Large scale computer simulations 9 7 11 5 3 100 inverters + 100 capacitive loads connected no ancillary services active Harmonic impedance measured at the substation busbar with 100 inverters as well as 100 capacitive loads connected. 13
  • 14. Large scale computer simulations 11 9 7 3 5 100 inverters + 100 capacitive loads connected limited VPCR active Harmonic impedance measured at the substation busbar with 100 inverters as well as 100 capacitive loads connected.Large scale computer simulations 100 inverters + 100 capacitive loads connected full VPCR active Harmonic impedance measured at the substation busbar with 100 inverters as well as 100 capacitive loads connected. 14
  • 15. Large scale computer simulations 100 inverters + 100 capacitive loads connected both VPCR and VRHD active Harmonic impedance measured at the substation busbar with 100 inverters as well as 100 capacitive loads connected. Conclusions Based on study, simulations and laboratory measurements: • VPCR virtually reduces capacitances that can bring resonances, • VPCR + VRHD virtually reduces capacitances and damp resonances. These two ancillary services can be implemented in power electronics based inverters for DG. The actual working range depends on the performance of the control system. Author Name-Country-SessionX- 30 P.J.M. Heskes Netherlands Session 2 Paper ID 0549 ID BlockY-Paper 15
  • 16. Thank you for your kindattention 16