Effective protection scheme for transmission lines connected to large scale photovoltaic power plants.

• This paper proposes a novel fast time-domain protection scheme in a large-scale PPP system, with prominent features such as simplicity. • There is no need of parameters tuning because of the adaptive nature of ITD. Also, all the protection scheme parameters are determined analytically, such as threshold value and number of iterations. • A wide variety of fault scenarios are analyzed for fault detection such as different fault resistance, location and types. • Communication medium is not required. Consequently, there is no communication delay and data loss. • The protection scheme's capability in various conditions such as noisy environments, uncertainty in renewable energy generation, change in GC, various sampling frequencies and CT saturation is discussed. • The proposed protection scheme is tested in two the 2-bus and IEEE 39-bus test systems in MATLAB and PSCAD environments. The performance of a distance relay can be significantly affected by various uncontrolled factors such as fault resistance, fault type, fault location and noise. Moreover, when photovoltaic power plants are integrated into electrical grids, they exhibit distinct fault current characteristics compared to conventional power systems with synchronous generators. These factors introduce variations in the recorded apparent impedance, deviating from the predefined settings of the distance relay. This paper presents an effective scheme for fault detection using ITD methodology. The ITD method decomposes the target signal into proper rotation and monotonic signals, which are then used to calculate the Energy Index. The performance of this scheme has been extensively investigated under various scenarios, including fault resistance, fault location, fault type, CT saturation, GC compliance, noise, and sampling frequency. To validate the effectiveness of the proposed scheme, simulations are conducted using both the PSCAD/EMTDC and MATLAB software. The proposed scheme is assessed using both the 2-bus and IEEE 39-bus test systems. The results show the merit and effectiveness of the proposed scheme in the accurate diagnosis of fault detection with 400 Ω fault resistance, in the presence of 20 dB noise, with variable sampling frequency (0.5-16 kHz) and variable irradiance values (600-1000 (W / m 2)) in power systems. [ABSTRACT FROM AUTHOR]