TRANSIENT AND STEADY-STATE STABILITY ANALYSIS OF SOLAR PV- WIND GRID-TIE HYBRID SYSTEM

Abstract

The global energy landscape is rapidly evolving towards increased reliance on renewable energy sources, driven by concerns over climate change and the finite nature of fossil fuels. However, the integration of variable and intermittent renewable energy sources into the electricity grid presents significant challenges to grid stability and reliability. This study presents a comparative analysis of Solar PV-Wind HRES Gid-Tied System and Solar PV-Wind-Battery HRES Gid-Tied System based on transient and steady-state stability analysis. The systems were simulated using the Electrical Transient Analyzer Program (ETAP®) and Grid-tied to an IEEE 14-bus system. For transient analysis, two common grid disturbances were explored, i.e., Line to Ground faults on buses and faults on the transmission line at different fault positions i.e., 0%, 10%, 25%, 50%, 75%, 90%, and 100% with a fault clearance time of 1.05 s, 1.50 s, and 2.00 s, and the fault set to occur at 1.00 s with a simulation time of 50 s. For steady-state stability, irradiation and wind speed were gradually varied, and Eigenvalue Analysis was performed to assess the dynamic stability of the power system under steady-state conditions. Lastly, ANOVA analysis was performed to analyze the effects of fault position on a transmission line, fault clearance time, and the presence of a battery energy system on the system setting time after a fault occurred based on generator speed, voltage, and frequency. For the Solar PV-Wind HRES Gid-Tied System, it was established that the voltage and frequency profiles at the Bus with the fault dropped significantly during the fault but recovered to their pre fault level after the fault was cleared for all the explored fault clearance-time. However, a larger fault clearance time (2.00 s) had a longer settling time. Additionally, the eigenvalue analysis established that all eigenvalues were located in the left half of the complex plane, indicating a stable system. Furthermore, there were statistically significant differences between the explored fault clearance times. For the Solar PV-Wind-Battery HRES Gid-Tied System, it was established that the BESS enhanced the stability and efficiency of an HRES with voltages ranging from 0.98772 to 1.000 p.u. Additionally, there was a statistically significant interaction between the effects of fault clearance time and battery on the settling time for voltage, frequency, and generator speed. In comparison, the settling time for the Solar PV-Wind-Battery HRES Gid-Tied System was lower than that for the Solar PV-Wind HRES Gid-Tied System. Therefore, the battery energy system effectively compensates for the inherent variability of renewable energy sources, preventing cascading failures and ensuring system robustness. Additionally, to further improve the performance of the Solar PV Wind-Battery HRES Grid-Tied System, the implementation of adaptive control strategies such as real-time dynamic droop control or predictive battery dispatch algorithms is recommended. These strategies can enhance the responsiveness of the BESS during fault events, reduce overshoot and oscillations, and ensure faster system stabilization, especially under high-variability renewable input conditions.