abstract: in this paper a control scheme for grid-connected operation mode and the island state of distributed generation is presented. in normal conditions, every inverter dg system in micro-grids to supply a preset power, normally operate in a constant current control mode. when micro-grids removed from the network, dg inverter of each system must recognize the island and change position to v...

Controlled islanding has been widely discussed in the literature as a novel concept for the power system protection. However, the islanding can result in unbalanced islands where the power mismatch will often cause an instability that can lead either to a subsequent load shedding or generator tripping within the islands. Controlled VSC-HVDC links can mitigate the negative consequences of the co...

The system response to accidental islanding and effect on anti-islanding detection of distribution feeders with multiple distributed generation (DG) technologies (synchronous machine and inverterbased units) is one major utility concern associated with increasing penetration of DG. Studies have been conducted to evaluate the performance of anti-islanding detection through use of conventional vo...

This paper introduces a new islanding detection algorithm method based on voltage and frequency analysis for wind turbines as distributed resource units at the distribution voltage level. The proposed method is based on processing of the rate of change of q-axis component of voltage and accelerates of change of frequency. This method detects the islanding conditions with the analysis of these s...

Islanding is detected by all distributed generations (DGs), especially those connected at secondary distribution grids. Islanding methods are mainly classified in three main categories: Passive, Active, Communication based. Hybrid methods are first time discussed in this paper. These methods are under evolution and as their advantages are coming they become an important part of islanding detect...

The proposed method develops a fuzzy rule-based classifier that was tested using features for islanding detection in distributed generation. In the developed technique, the initial classification boundaries are found out by using the decision tree (DT). From the DT classification boundaries, the fuzzy membership functions (MFs) are developed and the corresponding rule base is formulated for isl...

The objective is to minimize the fuel cost during the grid-connected operation, while ensuring stable operation after islanding. To achieve this goal, the economic dispatch (ED) problem and related constraints are formulated. The constraints considered in this study are: i) reserve for variation in load demand, ii) reserve for variation in the power outputs of non-dispatch able DGs, iii) flow l...

Economical harvesting of electrical energy on a large scale considering the environmental issues is a challenge. As a solution, Microgrids (MGs) promise to facilitate the widely penetration of renewable energy sources (RESs) and energy storage devices into the power systems, reduce system losses and greenhouse gas emissions, and increase the reliability of the electricity supply to the customer...

This paper presents actual cases of steady reactive power oscillation of Distributed Generations (DGs) during parallel operation with the main grid. The cause of the problem was found to be the adverse effects of excitation system voltage regulation. It is shown, through preliminary investigation and detailed simulation studies, that how the excitation control system can be modified to overcome...