Optimal Power Control of Inverter-Based Distributed Generations in Grid-Connected Microgrid

Abstract

Distributed generation (DG) units are utilized to feed their closed loads in the autonomous microgrid. While in the grid-connected microgrid, they are integrated to support the utility by their required real and reactive powers. To achieve this goal, these integrated DGs must be controlled well. In this paper, an optimal PQ control scheme is proposed to control and share a predefined injected real and reactive powers of the inverter based DGs. The control problem is optimally designed and investigated to search for the optimal controller parameters by minimizing the error between the reference and calculated powers using particle swarm optimization (PSO). Microgrid containing inverter-based DG, PLL, coupling inductance, LC filter, power and current controllers is implemented on MATLAB. Two microgrid cases with different structure are studied and discussed. In both cases, the microgrid performance is investigated under different disturbances such as three-phase fault and step changes. The simulation results show that the proposed optimal control improves the microgrid dynamic stability. Additionally, the considered microgrids are implemented on real time digital simulator (RTDS). The experimental results verify the effectiveness and tracking capability of the proposed controllers and show close agreement with the simulation results. Finally, the comparison with the literature confirms the effectiveness of the proposed control scheme.

A Review of Microgrid Energy Management and Control Strategies

“…One of the prerequisites for this type of control is a voltage reference for it to follow, which, as explained previously, is either provided by the primary grid or a grid-forming DER. Real and reactive powers can be controlled independently due to decoupled of direct and quadrature reference currents, as presented in (11) and ( 12) [131].…”

“…A power flow regulator is applied in the secondary and tertiary control layers to smoothen the connection transient process and control power flow among sub-microgrids. In [131], an optimal PI-based PQ control scheme is proposed for grid-connected microgrids, where the control parameters are tuned using PSO by targeting the minimization of error between the reference and calculated power values. Ref.…”

Integration of AC/DC Microgrids into Power Grids

“…M. A. Hassan, et al [9], in their paper entitled "Optimal Power Control of Inverter-Based Distributed Generations in Grid-Connected Microgrid", proposes an efficient PI power controller to regulate the predefined injected real and reactive powers to the grid. The control problem is optimally designed based on minimizing the error between the calculated and the injected powers to get the optimal controller parameters.…”

Miniaturized Distributed Generation for a Micro Smart Grid Simulator

“…However, the micro DG that plays the role of DG in the micro SG simulator, which is essential in verifying the control algorithms of the SG experimentally, remains hitherto unexplored. Several researchers proposed grid connection methodologies of DG for SG [22][23][24]; however, they cannot be applied directly to the micro SG simulator because of the large differences in the size and power levels of the DG systems. To realize this new method, a miniaturization method that can downscale the size and power levels to that of a micro SG simulator needs to be developed.…”