Protection Scheme for Optimal Allocation of Green Distributed Generation in Iraqi Distribution Grid

Abstract

The integration of green Distributed Generation (GDG) with Distribution Networks (DNs) was formulated in response to heightened operational efficiency and sustainability considerations. Following the penetration of GDG, significant alterations occurred in important electrical features, such as short-circuit current, pick-up current, voltage profile, power losses, and power flow direction. Therefore, this embedded increased the complexity of the protection scheme design. In the context of this research, a comprehensive investigation to determine the optimal location, quantity, and capacity of Photovoltaic-Green Distributed Generation (PVGDG) penetrations within DN. The study used the particle swarm optimization (PSO) technique and the Newton-Raphson (NR) methodology for case studies. Furthermore, ascertain the thermal thresholds for electrical equipment functioning within the DN. Additionally, conduct computations for anticipated fault currents, aiming to establish optimal setting and coordination for both primary and backup Protective Devices (PDs) employed in the DN. The IEEE 33-bus test system was employed to validate the accuracy of the algorithms and program results about power flow, optimization, Thermal Limit Factor (TLF), short circuit analysis, and the Time-Current Characteristics Curve (TCCC) against comparable outcomes. Furthermore, the practical application of the research process and findings was simulated using the 11 kV and 0.416 kV of the Iraq-Baghdad distribution network as a real-world case study. MATLAB 2022b was utilized for the implementation of optimization method and TLF calculations. CYMDist 9.04, on the other hand, served as the tool for simulating electrical networks. It facilitated the determination of power flow outcomes, and short circuit currents, including coordination analysis features for the representation of the TCCC. This analysis was contingent upon PDs parameters, ensuring robustness and appropriate resetting to achieve optimal operation without temporal intersections. Besides, the PVsyst program played an important role in designing the PV-GDG for enhanced precision in all analyses and results. The study findings indicate that integration 4 MW, whether at an optimally centralized bus of 11 kV or dispersed near 0.416 kV consumer load points in the feeder network, alters critical electrical elements. During daylight of Peak Sun Hour (PSH), active power losses decrease (9.3% to 40.75%), and voltage profile improves (3.1% to 14.1%). Additionally, adjusting parameters (TD, PS, DT, CM, and TM) in the new setting and coordination allows continued use of the same PDs without replacement. This supports the implementation of a resilient protection strategy effective both before and after embedding PV-GDG within the DN.