The reliable and safe operation of any transmission system demands the early detection, classification and location of faults, so as to allow possible isolation at the earliest and hence minimize cost and manpower. The protection task becomes quite challenging in the presence of compensating devices like STATCOM, which are introduced to improve stability. With the integration of STATCOM in the transmission line, the conventional distance relay maloperates during faults due to the errors introduced in the impedance measurement. The book presents a simple and intelligent data mining based protection approach for three phase transmission system incorporating STATCOM in the middle of the line. This book is based on the research conducted in National Institute of Technology Raipur, India. This book will be a good reference to scientists, researchers and engineers working in transmission line protection.