Islanding Detection Time Research Articles

A Communication Based Islanding Detection Method for Photovoltaic Distributed Generation Systems

PV based distributed generation (DG) systems must have some electrical connection standards while they connected to an electrical grid. One of these electrical conditions and the most important one is unplanned islanding condition. Islanding is a very dangerous condition because it could damage the PV system and related electrical systems and also working people have been at risk in islanding condition. In this application study, a new communication based islanding detection method was introduced for grid tied PV systems. A real time controller was developed with Labview for detecting islanding condition. Developed method is a hybrid method which uses the effective ways of communication based and passive methods. The results obtained from the proposed real time islanding detection method show that proposed method is reliable, robust, and independent from load and inverter. Nondetection zone (NDZ) is almost zero and islanding detection time is approximately 1-2 cycles indicated in experimental results so this time has a significant short response time according to IEEE 929-2000 standard. The proposed method is effective and presents a realistic solution to islanding so it could be implemented easily to grid tied PV systems and could be used in real system applications.

Investigation of Positive Feedback Anti-Islanding Control for Multiple Inverter-Based Distributed Generators

The positive feedback-based anti-islanding scheme has become a common anti-islanding protection technique for inverter-based distributed generators (DGs). This paper investigates the scheme's impact on the small-signal stability of multiple inverter-based DGs installed in power distribution systems during grid-connected operation. The interactions among multiple-DGs due to the anti-islanding scheme are also addressed. An index is proposed to quantify the destabilizing effect of the aggregated positive feedback activities of multiple DGs. This paper further introduces a DG power transfer limit versus islanding detection time curve to reveal the conflicting requirements of anti-islanding protection speed and the maximum power transfer of multi-DG systems.

Impact of Positive-Feedback Anti-Islanding Methods on Small-Signal Stability of Inverter-Based Distributed Generation

This paper investigates the impact of positive-feedback anti-islanding methods on the small-signal stability of grid-connected inverter-based distributed generation. The maximum power transfer capability of a distributed generator (DG) is analyzed. Sensitivity studies are conducted for DGs equipped with the Sandia frequency shift anti-islanding scheme. Factors such as positive-feedback gain, initial chopping fraction, local load level, and network line impedance are investigated. The maximum power transfer limit versus positive-feedback gain curve is proposed as an index for the stability analysis. The results show that the positive-feedback anti-islanding scheme does have the potential to destabilize the grid-connected DG system when the grid is weak or the DG size is large. A curve that relates the maximum stable DG power transfer level versus the islanding detection time is proposed to quantify the destabilizing effect of the positive-feedback-based anti-islanding schemes.