The Innovative Method of Islanding Detection Based on the Unbalance Voltage Parameters with Frequency Control Loop

摘要

Repeatedly events and blackouts are of the most important accidents and threats tothe security of power systems. A division of the network structure and intentionalislanding are of the most important characteristics of a power system in the processof blackouts. One of the suitable ways for improving the security of the powersystem in this context is the division of power network into suitable controlledintentional islands; if the system is going to be destroyed, it is possible to divide thenetwork to controllable islands that decreases the risk level and black-out time. Onthese days’ power networks that their application of distributed generation units isincreasing, the units can have significant influence in independent islanding whilerepeating events occur. Islanding or disconnecting main network happens whensupplying power from a main network because of some reasons is stopped whiledistributed generation units are still serving the system. islanding has negativeeffects on protection and usage of the distribution system, islanding should beeffectively detected and the distributed system unit will be separated. One of theadvantages of distributed generations in the grid is using the capacity of these unitsas the back-up for providing local load while losing main source. In thesecircumstances it is possible to divide a distribution network into islands that stabilityis maintained because of existing distributed generation sources and using power ineach island. Synchronous generator is used in this case as a distributed generationand unbalanced voltage parameter with controlling frequency loop is adapted forislanding process detection. Finally, the suggested method is tested on both systemsand the result is reported.