Approach for Islanding Detection in a PV Grid-Connected System Using Negative Sequence Impedance

Photovoltaic (PV) power systems that are linked to the grid have the advantage of being quick and dependable sources of electricity. The power industry has been obliged to transition over to more PV-penetrated distributed generation as a result of solar energy's favorable environmental effects in order to keep up with rising load demand. In grid-tied, PV systems, the issue of unintentional islanding in grid connectivity still presents a barrier. Therefore, quick islanding detection is required for efficient and trustworthy functioning of the system. This paper proposes a passive islanding detection method based on negative sequence impedance computation at the Point of Common Coupling (PCC) for a PV interconnected grid system. The approach is simulated and tested under several test scenarios. By determining the reciprocal of square root of the obtained Negative Sequence Impedance (NSI) at the PCC, which is calculated from the ratio of negative sequence voltage and negative sequence current found at PCC, the islanding mode is identified. By identifying the Non-Detection Zone (NDZ), that fulfils the IEEE requirements of execution time of 2 s, the results of this technique have been achieved and confirmed. A 100 kW of PV integrated grid system is used for the study using MATLAB/Simulink (version 2018a).