Integration of multiple ultra-capacitor banks in DC microgrid part I

• Main Author: Ahamad Fareed
• Other Authors: Wang Peng
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10356/78000
• Institution: Nanyang Technological University

DC Microgrid (Mg) is a small-scale power supply network that is designed to provide power to DC loads. It is an efficient and economical energy system comprising of different renewable sources and storages that are interconnected to meet the power demand from the load. Energy Storages (ES) are used in the DC Mg to mitigate the differences between the load demand and the generations. One such ES is the ultracapacitor bank (UC). An example of its application is to compensate the power deficiency or surplus during motor starting and shutting down to ensure system power quality. However, with increased load demand mounting, a single UC is no longer feasible to simultaneously provide for all the possible loads and to maintain long-term operation. Therefore, there is a need to configure multiple UC banks in the DC Mg for economic operation of the entire system. To form a Hybrid Energy Management System (HEMS), proper control algorithms need to be in place for optimal load sharing between the ESs. Furthermore, an alternative energy source could be added to improve reliability, overall efficiency, and to reduce the electrical stress of the system. As such, this project will conduct some studies on the various control algorithms used for the DC-DC converters connected to the ESs. These control algorithms include the droop control and integral droop control. The droop and integral droop control algorithm allow power sharing amongst the batteries in proportion to their power rating and amongst UCs according to the inverse of their integral coefficients. Moreover, integral droop control is needed for the UCs to remain in standby during steady-state operation due to its low energy density. Maximum Power Point Tracking (MPPT) mechanism is implemented on the alternative energy source chosen, to achieve maximum output power. State of Charge (SoC) is also implemented to improve performance of UCs during heavy load switching. The setup of this project will include ESs and sources connected in parallel branches to form a HEMS. Each branch will feature a bi-directional DC-DC boost converter to realize the desired 170V rated voltage of the DC Mg. The report will conclude from the results drawn from the output power sharing in the HEMS with all the needed control algorithms in place. The control algorithms and circuit schematics are designed using MATLAB Simulink software.