TESTING OF ALGORITHMS FOR A STAND-ALONE DIGITAL RELAY FOR POWER TRANSFORMERS

A stand-alone digital relay has been designed and implemented, The rel ay can be modified easily to accommodate the protection of different t ypes of transformers by changing the software only, Presented in this paper are the real-time experimental results of five selected algorith ms implemented using this digital relay. These algorithms are: discret e Fourier transform, Walsh function, rectangular transform, finite imp ulse response and least-square. Based an the experimental results, the discrete Fourier transform (DFT) algorithm is found to be the best al gorithm in terms of accuracy and speed for digital implementation of t he differential relay for power transformers.