Recently, microgrids have faced a great challenge for the stable operation of converter-dominant system with very high renewable penetration. The converter-based-generator reduces inertia constant. In this case, very small power imbalance can cause large frequency variation. Therefore, the accurate load sharing between generators is important for the stable operation. This paper proposes the virtual multi-slack (VMS) droop control based on the power sensitivity analysis. In other words, one physical slack generator directly controls the magnitude and phase angle of its bus voltage. At the same time, the other generators indirectly control the magnitudes and phase angles of their bus voltages by using the VMS droop control. This results in the proper load sharing between the generators in the stand-alone microgrid. That is, all nonslack generators operate as virtual slacks so that they solve the power imbalances together with one physical slack generator. The proposed VMS control is realized with the multi-slack power flow analysis, which enables adaptive droop based power allocation between the generators. Then, its effectiveness is verified with several case studies on the practical stand-alone microgrid in South Korea by using the electromagnetic transient program.
Bibliographical noteFunding Information:
Manuscript received July 31, 2017; revised December 22, 2017; accepted February 12, 2018. Date of publication February 28, 2018; date of current version April 17, 2018. This work was supported in part by the National Research Foundation of Korea funded by the Korea government (MEST) under Grant 2016R1E1A1A-02920095 and in part by the Korea Electric Power Corporation. Paper no. TPWRS-01136-2017. (Corresponding author: Soo Hyoung Lee.) D. Choi is with the Korea Telecom, Seoul 03155, South Korea (e-mail: email@example.com).
All Science Journal Classification (ASJC) codes
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering