A Series-LC-Filtered Active Damper for AC Power Electronics Based Power Systems

Transcription

1 A Series-LC-Filtered Active Damper for AC Power Electronics Based Power Systems Xiongfei Wang, Ying Pang, Poh Chiang Loh, Frede Blaabjerg Department of Energy Technology Aalborg University, Denmark

2 Outline Background and Challenge Series-LC-Filtered Active Damper Performance Validation Conclusions IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 2

3 Background Power Electronics Based Power Systems IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 3

4 Background Changes with Power Electronics Traditional Generator Prime Mover Excitation Control 0.1Hz 1Hz Traditional Generator Output Voltage Turbine P & ω Control 0.1Hz Large Wind Generator Grid Q &V Control DC-Link Control Grid Synchronization Current Control 10Hz 50Hz 500Hz Wind Generator Output Voltage Semiconductor Switching 2500Hz Harmonic Spectrum IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 4

5 Challenge Cost-effective diode rectifiers low-order (50 Hz - 2 khz) harmonics Increasing high-order (2 khz khz) switching harmonics Wideband controller interactions of converters harmonic instability IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 5

6 Challenge Stabilizing converter-converter and converter-grid interactions Variable damping of harmonic resonance High dc-link voltage for high-frequency output current IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 6

7 Series-LC-Filtered Active Damper Series ac capacitor for reduced dc-link voltage LC-filter resonance frequency < system resonance frequency Capacitive filter plant below the filter resonance frequency T Current control of grid converters connected with series ac capacitor IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 7

8 Series-LC-Filtered Active Damper Resonance Detection DC Voltage Control AC Current Control IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 8

9 Series-LC-Filtered Active Damper Resonance Detection for Unknown Frequency Generalized Integrator (GI) Adaptive Notch Filter (ANF) Frequency-Locked Loop (FLL) Pre-filtered ANF (P-ANF) X. Wang, F. Blaabjerg, and M. Liserre, An active damper to suppress multiple resonances with unknown frequencies, IEEE APEC 2014, pp IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 9

10 Series-LC-Filtered Active Damper DC-link voltage control q-axis k pda k ida s AC current control proportional control s k s res 2 2 res V AD1 < V pcc1 P>0 IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 10

11 Series-LC-Filtered Active Damper Why aligning at q-axis? q V LCfa1 V AD1 k p i L1 V AD1 k p i* L1 V LCfa1 V LCfa1 k p i* L1 k p i L1 * V AD1 V AD1 V AD1 k p i L1 k p i L1 V pcc1 d i L1 d-axis (inductive Q) q-axis (capacitive Q) Inherent positive feedback when aligning the reference at d-axis IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 11

12 Performance Validation Unstable current control of grid converter L g = 0.9 mh L g = 1.8 mh IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 12

13 Performance Validation Stable current control of grid converter with active damper FFT of V pcc : [50 V/div] [250 Hz/div] V pcc : [500 V/div] [4 ms/div] Current of grid converter PCC voltage DC-link voltage and ac current of damper Damper current spectra IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 13

14 Conclusions A series-lc-filtered active damper is proposed for stabilizing ac power electronics based power systems. An inherent positive feedback is elaborated when aligning the current reference at the d-axis. Experimental results validate the performance of the proposed active damper. IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 14

15 Acknowledgement Harmonic Identification, Mitigation and Control of Power Electronics Based Power Systems - HARMONY IEEE JESTPE Special Issue on Harmonic Stability and Mitigation in Power Electronics Based Power Systems Extended Deadline: May 15, 2015 IEEE APEC 2015 CHARLOTTE XIONGFEI WANG 15

16 Thank You! Questions? THE HIDDEN HARMONY IS BETTER THAN THE OBVIOUS - P. PICASSO