A Digital Control System for UPS Systems with Smart
Grid Capability
Mardani Boroujeni, Fatemeh
THESIS
SUBMITTED TO THE FACULTY OF GRADUATE STUDIES
IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF MASTER OF SCIENCE
GRADUATE PROGRAM IN ELECTRICAL ENGINEERING
UNIVERSITY CALGARY, ALBERTA
AUGUST, 2019.
Abstract
Smart grids have recently become the center of attention for modernizing the grid system.
In future smart-grids, energy storage systems are one of the key components, which
can complement intermittent renewable energy sources and in turn increase reliability and
eciency of the grid system. Modern Uninterruptible Power Supply (UPS) systems can
provide storage capacity for future smart grids since they usually include batteries. UPS
systems can also provide instant electrical power to sensitive equipment and grid during
various events such as brownout, power failures, spikes, voltage surges, EMI/RF noise, and
frequency variations.
Future UPS systems require to have much better dynamics in order to deal with transients.
The control system of UPS systems mainly determines their dynamical performance
and transient response. The existing state-of-the-art UPS control systems are based on linear
PI controllers for the most part. Thus, current UPS systems usually show a sluggish
transient response and they are not suited for future smart grid applications where instant
power is required to maintain the system.
In this thesis, new UPS systems with improved transient response are proposed. The
proposed UPS system utilities a new controller that is able to improve the dynamic performance
and allows for various smart grid functionalities. The proposed control system is
based on the adaptive control theory, which adaptively changes the controller's parameters
based on the UPS operating conditions. Furthermore, the proposed control system isolates
the double-frequency ripple from the battery in the normal/charging mode as well as in the
backup/discharging mode. Therefore, the new UPS system is well-suited for single-phase
systems utilizing lithium-ion battery as storage.
Mathematical analysis, simulation, and experimental results are presented to verify the
performance of the proposed control system and demonstrate its superior performance.
Nenhum comentário:
Postar um comentário