Effect of distributed generation systems on distribution networks

Recent developments in the renewable energy sector show that wind turbine as distributed generation systems in the distribution network increases their popularity as a new energy source. One of the important factors associated with the traditional network is the inadequacy of the protection and setting scheme when the distributed generation system is connected to the network due to the protection and control requirements of the distributed generation systems that are different from the transmission network. Thus, the interconnected system constantly faces new challenges in therms of power system stability. To overcome the challenges or at least alleviate the effect of the challenges, the dimensions of distributed generation systems must be appropriate distribution system. In this thesis, the effects of distributed generation systems on the distribution network during the fault conditions are examined. Fault conditions include shortcircuit faults, transient events and voltage sags. As a protection system against these conditions, the breakers should be performing robust, efficient and fast switching tasks. Also, an inverse time overcurrent relay is used for the breakers to make effective, fast switching to eliminate the faults. This thesis can be also examined for other sources such as photovoltaics, but only wind turbines have been discussed in this thesis. The IEEE 30-bus distribution system has been analyzed by the PSCAD/EMTDC program for different fault scenarios. Particular busses in this distribution system are selected for fault analysis and the installation of wind turbines. The power of wind turbine is determined by the total of the loads after the bus connected to wind turbine. The analysis is also done with the wind turbine which has a power capacity 50% more than obtained before. The pre-fault current and voltage values of busses are obtained with and without wind turbine before the faults. Then, phase to ground and three-phase to ground faults are occured in these buses and the protection system is provided to clear the faults. Finally, the current and voltage values during faults are obtained in the buses. Also, the current and voltage graphs of the buses are plotted.