Abstract:
The electrical distribution system ensures reliability in terms of availability of electric power for
specific loads, even then the concerns of voltage stability and power-sharing exists. In this thesis,
we investigate the performance of a microgrid during voltage sag/swell and unbalanced load
conditions in grid-connected mode. In islanding mode control of active and reactive power
independently is implemented to fulfill load demand. During the grid-connected normal operation
mode, the electric grid provides continuous active and reactive power injection to load and battery
storage is charging at constant power. During voltage sag/swell D-STATCOM draw/inject reactive
power to maintain the AC voltage at the point of common coupling (PCC) and constant flow of
power towards battery storage is maintained. During the islanded mode we know that AC load
consumes more reactive power and the battery storage doesn’t have too much capability to fulfill
reactive load demand and to maintain a constant voltage and frequency operation. Flexible AC
Transmission System (FACTS) devices like D-STATCOM are used to improve the power system
stability of the distribution system and enhance the transient stability with smooth voltage recovery
by injecting or absorb reactive power. When D-STATCOM is integrated with Battery storage it is
capable of draw/inject both active and reactive power. Buck and boost converter ensures constant
DC voltage in grid-connected as well as in islanding condition with proposed VSC. Therefore, A
New controlled strategy has been proposed where D-STATCOM is attached at a substation to
fulfill reactive load demand and the battery storage to fulfill active load demand independently.
This research aims to build a coordination scheme in which D-STATCOM and VSC are connected
through power electronics interfaces. These power electronics interfaces are decoupled control
with Proportional-integral (PI) control, Fixed-frequency sliding mode control (FFSMC) and
Fractional-order sliding mode control (FOSMC) to check the controller performance. The
simulation will be done in MATLAB Simulink in both grid-connected as well as islanding
condition.
