الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Power system is considered to be one of the most sophisticated networks which consists of electrical, mechanical, electronic and control hardware designed, built and operated by electrical engineers. The function of a power system is to deliver electrical energy as economically as possible with minimum environmental impact such as reduction in carbon dioxide (CO2) emission. In addition, the transfer of electrical energy to the load centers via transmission and distribution systems are achieved with maximum efficiency and optimum reliability at nominal voltage and frequency. In view of this, the establishment of the system is considered to be the most expensive in terms of capital investment.
Nowadays, because of technological advancement, industrial globalization and continuous increasing levels of network integrations, the grid system is increasingly vulnerable and sensitive to system disturbances. Such events may be due to switching activities (i.e. ON and OFF) of loads, or as a result of component switching such as reactor switching, the energisation and de-energisation of system components for commissioning and maintenance purposes. Other sources of switching events are the switching off of protection zones after the occurrence of short-circuit, or a lightning stroke impinging to the nearest high-voltage transmission line. For these reasons, the systems are never operated in a continuous steady state condition, it is a system consisting of a mixture of normal operating and transient states. Depending on the circuit configuration, the large number of various sources of capacitances in the network and certain sequence of switching events, a low frequency transient known as ferroresonance can be happened at the system. The word ferroresonance means the resonance between the network parameters with ferromagnetic material, particularly with the presence of power transformers working at no-load condition [10].
In recent years the number of ferroresonance incidents has increased due to network complexity and improved equipment efficiency [17].