Islanding condition means the case of feeding the loads from any distributed generator (DG) with a complete disconnection of the utility grid at the point of common coupling. The main technical issue in DG integration with the primary grid is the islanding condition. Hence, islanding must be detected using an appropriate anti-islanding technique which is needed to be faster in terms of time detection and accuracy. This paper illustrates the phenomenon of islanding and the passive methods which are used for preventing it. The main contribution of this paper is to detect this phenomenon as fast and accurately as possible using the technique of rate of change of power (ROCOP) based on the terminal voltage (TV) (ROCOP-TV) of the Photovoltaic (PV) inverter. The results of the proposed technique have been studied through extensive simulations using the MATLAB/Simulink platform. The ROCOP-TV technique results are compared with various types of passive detection relays after synchronization between the grid side and PV side. Furthermore, the proposed technique was not only able to detect islanding at the instance of its occurrence but also can distinguish between islanding and regular grid faults. The simulation results illustrate the proposed scheme's effectiveness and flexibility based on the MATLAB/Simulink platform.

Distributed generation (DG) has reformed the meaning of power generation from large scale to small scale, but unintentional islanding is the main issue when connecting DG and the utility grid. A lot of techniques have been used for detecting islanding, among these techniques, there are passive and active. The main problem of passive techniques is their large non-detection zone (NDZ), while the main drawback of active techniques is their undesirable effect on power quality. In this paper, a proposed hybrid passive–active systematic methodology based on a smart classifier that decides to use an active method instead of a passive one is presented. In the proposed scheme, sensors are used for measuring the reactive power at three terminals: the DG terminal, grid terminal, and load terminal. The novelty in this paper is the accurate detection of islanding within a shorter time either in the normal case or NDZ; also it can differentiate between islanding and grid faults without degrading the power quality of the overall system as the active technique does not have to be used continuously, and so total harmonic distortion does not exceed the standard value (5%) detected by IEEE standards. The proposed scheme was simulated using the MATLAB/Simulink platform, and the results reflect its potential with a comparative study.

No abstract

No abstract