In South Korea, the stand-alone microgrid on an island has synchronous diesel generators and multiple distributed generations (DG) based on renewable energy, and energy storage systems (ESS). According to the active policy of government to develop eco-friendly microgrids with zero carbon emission, many diesel generators in stand-alone microgrids are being replaced by the DGs. It brings challenges on the operation and control of multiple DGs because this causes the lack of inertia, which is originally provided from the diesel generators. This paper proposes a new decoupled frequency and voltage controller for DGs, which is able to keep the grid frequency and voltage magnitude constant. For frequency control, a frequency recovery control loop is newly added to conventional droop and inertia control loops for both effective power sharing and stabilization of frequency response after a disturbance. For voltage control, the proposed controller regulates the grid voltage in an inertia-free mode, in which all diesel generators are disconnected, while providing the conventional reactive power-voltage droop control under a normal condition. Moreover, the adaptive power sharing strategy is newly proposed to avoid the overcharge/discharge conditions of ESSs. As the result, the proposed controller can enhance the resilience and increase the penetration of renewable energies to the stand-alone microgrid. To verify the effectiveness of proposed controller, several case studies are being carried out by using the practical data of a real stand-alone microgrid in South Korea.
Bibliographical noteFunding Information:
Manuscript received February 13, 2018; revised June 14, 2018; accepted August 2, 2018. Date of publication August 19, 2018; date of current version December 12, 2018. Paper 2018-PSEC-0145.R1, presented at the 2018 IEEE/IAS 54th Industrial and Commercial Power Systems Technical Conference (I&CPS), Niagra Falls, ON, Canada, May 7–10, and approved for publication in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Power Systems Engineering Committee of the IEEE Industry Applications Society. This work was supported in part by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) under Grant 2016R1E1A1A02920095 and in part by the Human Resources Development program of Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by Korea government Ministry of Trade, Industry and Energy under Grant 20174030201540. (Corresponding author: Jung-Wook Park.) The authors are with the School of Electrical and Electronic Engineering, Yon-sei University, Seoul 120-749, South Korea (e-mail:,email@example.com; firstname.lastname@example.org; email@example.com).
All Science Journal Classification (ASJC) codes
- Control and Systems Engineering
- Industrial and Manufacturing Engineering
- Electrical and Electronic Engineering