Optimized Active Power Management in Solar PV-Fed Transformerless Grid-Connected System for Rural Electrified Microgrid

摘要

Dynamic voltage instability is one of the major issues faced by grid-connected renewable energy systems due to fluctuations in the generation and sudden variation in the loads. The primary objective of this paper is to propose a method for constant power consumption from the grid to maintain a stable DC-link voltage during peak and nonpeak hours. It can be achieved by implementing an optimized active power management (OAPM) scheme between the photovoltaic (PV) and the grid by enabling a battery energy storage system (BESS). The intelligent constant power balance (ICPB) algorithm and detailed control strategies for dual active bridge (DAB) isolated DC-DC converter and grid-connected voltage source inverter (VSI) are discussed in this paper. Moreover, the high-gain step-up DC-DC converter (HSDC) is utilized to perform maximum power point tracking (MPPT) operation and to meet the required DC-link voltage. The accuracy of power transmission of DAB gets improved by imposing a curve-fitting interpolation (CFI) approach, thereby maintaining a constant DC-link voltage. Furthermore, an instantaneous sinusoidal current control (ISCC) scheme assures the feeding of active power with better power quality. The measured results are obtained and verified under different dynamic conditions of load and generation. Based on the validation, we conclude that the proposed OAPM scheme is most suitable for grid-connected renewable energy systems in the rural electrified microgrid.