Model Predictive Control for Three-Phase Split-Source Inverter-Based Virtual Synchronous Generator

Abstract

Realizing local voltage regulation and powersharing of an islanded AC microgrid can be achieved by conventional control that employs outer-loop droop control and inner-loop cascaded linear control. However, it has limited dynamic response, complex structure, and a rapid rate of change of frequency. In addition, the use of two-stage DC-DC-AC converters for interfacing the renewable energy sources and the microgrid reduces the system efficiency. The split-source inverter (SSI) introduces an alternative single-stage solution for the DC-DC-AC conversion. This paper proposes a virtual synchronous generator (VSG) control algorithm based on model predictive control (MPC) for a three-phase SSI. A finite-set MPC (FS-MPC) is employed to achieve a simple control structure, fast dynamic response, higher stability, and improved current limitation in the inner control loop. A VSG control algorithm without a phase-locked loop is utilized in this paper to achieve active-power-sharing and inertia emulation in the outer control loop. The analysis and modeling of the proposed technique are presented in detail. The simulation results verified the merits of the analysis and the theoretical finding.

Simplified three‐phase split‐source inverter for PV system application controlled via model‐predictive control

“…The reference power for the grid is the subtraction of the dynamics of the energy of the DC-side capacitor from the PV power. The reference dq grid currents are obtained from the reference active and reactive power from ( 24) and (25) as in (26) and (27). The reference reactive power Q ref is chosen to be zero, to maintain the injected current at the unity power factor.…”

“…The use of the model‐predictive control (MPC) strategy for SSI topologies has become widespread recently, 24–27 which is a proper control strategy for power electronics converters due to its discrete character. MPC uses a discrete‐time model of the controlled system to predict its future behavior for all the converter possible voltage vectors and uses a predefined cost function to obtain optimal action 28–30 .…”

Enhanced Finite Control Set-Model Predictive Control for Three-Phase Split-Source Inverters

“…Since the three-phase SSI utilizes the B6 bridge of the standard VSI, therefore, it uses the same switching vectors (𝑉 𝑜 − 𝑉 7 ), shown in Fig. 2 [20]- [24]. The inductor, 𝐿, and the diodes of Fig.…”

“…The finite control set MPC method for SSI connected to the grid is proposed in [20] and for standalone configurations in [21]- [23]. A virtual synchronous generator-based MPC for grid-connected SSI is presented in [24]. The cost function for the SSI is typically formulated by combining the system state errors (inductor current, capacitor voltage, and output currents) with appropriate weighting factors.…”