الفهرس 
Enhancing Distance Protection of Long Transmission Lines Compensated with TCSC and Connected With Wind Power
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Abstract
Power system is one of the most important systems that were developed by humankind. Basic function of power systems is to generate the electrical energy in power plants, transmit it to the required destinations and finally, distribute it to consumers. Each of these steps has its difficulties and importance. The locations of electrical energy production and consumption are away from each other, and thus transferring the energy by transmission lines becomes very important. One of the factors that can disturb performance of the transmission lines is short circuit faults that the lines must be protected against them by the distance protection devices. There are different challenges and difficulties facing the work of distance protection devices especially in long transmission lines. Moreover, the rapid growth in electrical power demand is a challenge for all energy systems around the world that requires constructing new generation stations and enhancing transmission and distribution facilities. Thyristor controlled series compensation (TCSC) is widely used in long transmission lines to mainly improve power transfer capability. However, TCSC produces complicated impedance that negatively affects distance protection operation. The wind energy generation system produces additional complexity to the distance protection performance due to the fluctuations of wind speed and variationsof fault current level.
This thesis proposes an integrated scheme to change adaptively the settings of the Mho distance protection by shifting the relay characteristics considering the bad impacts of TCSC, wind power and fault resistance. The proposed scheme achieves its main stages starting from fault detection, fault classification until relay tripping decision procedure including online estimation for preliminary fault location, impedance of TCSC and fault resistance using limited communication requirements as one time value is transferred in fault detection stage, while limited RMS values, not instantaneous values, are transferred in stage of online calculations of fault location and the remaining stages are dependent on local measurements.
By extensive MATLAB simulations, the performance of the proposed scheme is examined compared with the conventional Mho relays under different fault locations, fault inception angle, fault resistance, different wind power penetration, different wind speeds and different TCSC firing angles. The achieved results ensured that the proposed scheme improves significantly Mho distance relay operation and avoids under-reaching and over-reaching problems irrespective of the large shunt capacitance along the transmission line, and also without identifying the parameters of TCSC such as the capacitance, the inductance or the firing angle.Besides, the proposed method has proven its accuracy for different type of faults and at difficult cases where the fault occurs near the end of protection zones and near to buses.