In this paper, new optimal procedures are introduced to design the finest controllers and harmonic
compensators (HCs) of three-level cascaded control for three-phase grid-supporting inverters based-AC
microgrid. The three control levels, comprising primary, secondary and synchronization control levels,
are developed in stationary αβ-frame and based on the proportional–integral (PI) controllers and
the proportional-resonant controllers along with additional HCs. The new optimal design guidelines
of microgrid’s controllers and HCs are aimed to fulfill the study requirements. The optimization
objectives and constraints are employed to minimize both the total harmonic distortion (THD) and
individual harmonics of microgrid’s voltage to enhance the quality of microgrid’s output power.
The THD of microgrid’s voltage can be reduced to 0.19% under the nonlinear loads. Moreover, the
microgrid’s voltage and frequency can be perfectly regulated with zero deviations. Furthermore, these
new optimal procedures accelerate the speed of synchronization process between the external power
grid and the microgrid to be accomplished in time less than 20 ms. Additionally, an accurate powersharing
among paralleled operated inverters can be achieved to avoid overstressing on any one. Also,
seamless transitions can be guaranteed between grid-tied and isolated operation mode. The optimal
controllers and HCs are designed by a new optimization algorithm called H-HHOPSO, which is created
by hybridizing between Harris hawks optimization and particle swarm optimization algorithms. The
effectiveness and robustness of the H-HHOPSO-based controllers and HCs are compared with other
meta-heuristic optimization algorithms-based controllers and HCs. A microgrid, including two gridsupporting
inverters based optimal controllers and optimal HCs, are modeled and carried out using
MATLAB/SIMULINK to test the performance under linear and nonlinear loads, and also during the
interruption of any one of two inverters. The performance is investigated according to IEC/IEEE
harmonic standards, and compared with the conventional control strategy developed in synchronous
dq-frame and based on only PI controllers. |
