Power Sharing Between Islanded Microgrid Inverters by Modifying the Droop Control Method

Subject Areas : Intelligent Multimedia Processing and Communication Systems (IMPCS)

kiomars  sabzevari ¹ (Assistant Professor, Department of Electrical Engineering, Technical and Vocational University(TVU), Tehran, Iran)

Received: 2022-09-01 Accepted : 2023-06-02 Published : 2022-12-22

Keywords: Reactive power sharing, Frequency control, Droop Control, Voltage control, active power sharing,

Abstract :

Introduction: Distributed generation appears as the eco-friendly solution to a growing demand of electricity. Within the same idea, microgrids have become one of the most attractive sources of attention since they integrate local supply sources both with cleanliness and robustness. These microgrids can operate either connected to the utility grid, or on their own, namely the islanded mode. In the case of an island microgrid, how to control the DC bus voltage and the energy balance of the microgrid is necessary and essential for its use. Voltage and frequency control as well as active and reactive power sharing between distributed generation sources in island AC microgrids is one of the challenges of microgrid control. One of the control methods of islanded microgrids is to use the common droop control method. Although the droop control method can accurately divide the active power among distributed generation sources; But in the drop control method, reactive power sharing is not accurate.Method: In this article, the adaptive droop control method is used to compensate the voltage drop caused by the line impedance and increase the accuracy of reactive power sharing in the islanded microgrid. Communication between distributed generation sources is used to facilitate the adjustment of adaptive droop control during load changes. In the proposed method, there is an assurance that by cutting the connection between the scattered production sources, if the load does not change, the reactive power sharing will be done accurately. The proposed method has a better performance than the conventional droop control method.Results: The simulation of the proposed control method has been done using Simulink MATLAB. The simulation results show that the proposed control method has accurate reactive power sharing. And it has a better performance than the common drop method.Discussion: In the proposed control method, by compensating the impedance voltage drop of the transmission line to the common point of the units, the power sharing between the inverters is proportional to the capacity of the units. The simulation results show that reactive and active power division is performed accurately with the presence of a communication link between the units. In case of constant load and disconnection between the units, the power sharing between the units is accurate. In the case of disconnection of the communication link between inverters and load change, the proposed control method performs better than the conventional drop control method.

References:

• [1] C. Vasquez, J. M. Guerrero, J. Miret, M. Castilla, and L. Garc´ıa De Vicuna, “Hierarchical control of intelligent microgrids,” ˜ IEEE Industrial Electronics Magazine, vol. 4, no. 4, pp. 23–29,2010.


• [2] L. Vandoorn, J. C. Vasquez, J. De Kooning, J. M. Guerrero, and L. Vandevelde, “Microgrids,” Hierarchical control and an overview of the control and reserve management strategies”, IEEE Industrial Electronics Magazine, vol. 7, no. 4, pp. 42–55, 2013.


• [3] M. Guerrero, M. Chandorkar, T.-L. Lee, and P. C. Loh, “Advanced control architectures for intelligent microgrids - part I: Decentralized and hierarchical control” ,IEEE Transactions on Industrial Electronics, vol. 60, no. 4, pp. 1254–1262, 2013.


• [4] Parhizi, H. Lotfi, A. Khodaei, and S. Bahramirad, “State of the art in research on microgrids: A review” ,IEEE Access, vol. 3, pp. 890–925, 2015.


• [5] Han, X. Hou, J. Yang, J. Wu, M. Su, and J. M. Guerrero, “Review of power sharing control strategies for islanding operation of AC microgrids”, IEEE Transactions on Smart Grid, vol. 7, no. 1, pp. 200– 215, 2016.


• [6] Bidram and A. Davoudi, “Hierarchical structure of microgrids control system”, IEEE Transactions on Smart Grid, vol. 3, no. 4, pp. 1963–1976, 2012.


• [7] Kim, J. M. Guerrero, “Mode adaptive droop control with virtual output impedances for an inverterbased flexible AC microgrid”, IEEE Trans. Power Electron, vol. 26, no. 3, pp. 689-701, 2011.


• [8] Yao, M. Chen, J. Matas, “Design and analysis of the droop control method for parallel inverters considering the impact of the complex impedance on the power sharing”, IEEE Trans. Ind. Electron, vol. 58, no. 2,pp. 576-588, 2015.


• [9] c. Zhong, “Robust droop controller for accurate proportional load sharing among inverters operated in parallel”, IEEE Trans. Ind. Electron, vol. 60, no. 4, pp. 1281-1290, 2013.