A protection scheme for the transmission line connecting large-scale centralized solar PV plant

The grid connected large-scale solar photovoltaic (LS-SPVP) plants affect the performance of conventional distance relays protecting the interconnected transmission line. In this paper, an improved fault detection, classification and location estimation technique is proposed for such crucial transmission lines using the line end voltage and current measurements. The method utilizes the magnitude ratios of the line end phase currents for detection and classification of the fault. The apparent power delivered to the fault from both ends of the transmission line is used further for the estimation of fault resistance. Using the estimated value of the fault resistance, the incremental impedance, the actual value of the line impedance between the relay and the fault point and the exact location of the fault is calculated. Performance of the protection technique is verified on different fault and non-fault cases simulated on a test power system as well as on the IEEE 39-bus New England system connecting a 50 MW solar PV plant using MATLAB/Simulink. The efficacy of the proposed protection scheme is also validated through OPAL-RT (OP4510) make real-time digital platform. The obtained results clearly show that using the proposed method, fast and accurate detection, classification and location estimation of even high resistance faults up to 200 Omega can be achieved in LS-SPVP connected transmission lines.