Please wait a minute...
Front. Inform. Technol. Electron. Eng.  2013, Vol. 14 Issue (1): 50-64    DOI: 10.1631/jzus.C1200236
    
Analysis, design, and experimental evaluation of power calculation in digital droop-controlled parallel microgrid inverters
Ming-zhi Gao, Min Chen, Cheng Jin, Josep M. Guerrero, Zhao-ming Qian
Department of Applied Electronics, Zhejiang University, Hangzhou 310027, China; Institute of Energy Technology, Aalborg University, Aalborg 9000, Denmark
Download:   PDF(0KB)
Export: BibTeX | EndNote (RIS)      

Abstract  Parallel operation of distributed generation is an important topic for microgrids, which can provide a highly reliable electric supply service and good power quality to end customers when the utility is unavailable. However, there is a well-known limitation: the power sharing accuracy between distributed generators in a parallel operation. Frequency and voltage droop is a well-established control method for improving power sharing performance. In this method, the active and reactive power calculations are used to adjust the frequency and amplitude of the output voltage. This paper describes the digital implementation of a droop method, and analyzes the influence of power calculation on droop method performance. According to the analysis, the performance of droop control in a digital control system is limited by the accuracy and speed of the power calculation method. We propose an improved power calculation method based on p-q theory to improve the performance of the droop control method, and we compare our new method with two traditional power calculation methods. Finally, simulation results and experimental results from a three single-phase 1-kW-inverter system are presented, which validate the performance of our proposed method.

Key wordsDistributed generators      Distributed energy storages      Microgrid      Wireless parallel      Droop control      Digital control system      p-q theory     
Received: 08 August 2012      Published: 03 January 2013
CLC:  TM464  
Cite this article:

Ming-zhi Gao, Min Chen, Cheng Jin, Josep M. Guerrero, Zhao-ming Qian. Analysis, design, and experimental evaluation of power calculation in digital droop-controlled parallel microgrid inverters. Front. Inform. Technol. Electron. Eng., 2013, 14(1): 50-64.

URL:

http://www.zjujournals.com/xueshu/fitee/10.1631/jzus.C1200236     OR     http://www.zjujournals.com/xueshu/fitee/Y2013/V14/I1/50


Analysis, design, and experimental evaluation of power calculation in digital droop-controlled parallel microgrid inverters

Parallel operation of distributed generation is an important topic for microgrids, which can provide a highly reliable electric supply service and good power quality to end customers when the utility is unavailable. However, there is a well-known limitation: the power sharing accuracy between distributed generators in a parallel operation. Frequency and voltage droop is a well-established control method for improving power sharing performance. In this method, the active and reactive power calculations are used to adjust the frequency and amplitude of the output voltage. This paper describes the digital implementation of a droop method, and analyzes the influence of power calculation on droop method performance. According to the analysis, the performance of droop control in a digital control system is limited by the accuracy and speed of the power calculation method. We propose an improved power calculation method based on p-q theory to improve the performance of the droop control method, and we compare our new method with two traditional power calculation methods. Finally, simulation results and experimental results from a three single-phase 1-kW-inverter system are presented, which validate the performance of our proposed method.

关键词: Distributed generators,  Distributed energy storages,  Microgrid,  Wireless parallel,  Droop control,  Digital control system,  p-q theory 
[1] Lu-jun Wang, Tao Yang, Da-min Zhang, Zheng-yu Lu. A high performance simulation methodology for multilevel grid-connected inverters[J]. Front. Inform. Technol. Electron. Eng., 2012, 13(7): 544-551.
[2] Arash Khoshkbar Sadigh, Gevorg B. Gharehpetian, Seyed Hossein Hosseini. New method for estimating flying capacitor voltages in stacked multicell and flying capacitor multicell converters[J]. Front. Inform. Technol. Electron. Eng., 2010, 11(8): 654-662.
[3] Jian-yu Bao, Wei-bing Bao, Zhong-chao Zhang. Generalized multilevel current source inverter topology with self-balancing current[J]. Front. Inform. Technol. Electron. Eng., 2010, 11(7): 555-561.