TMS320F28335 based single phase overcurrent protection Implementation using Numerical Relay

Power Systems suffer from various types of faults such as Phase and Earth Faults. These faults lead to overcurrent in the circuits. Numerical Relays embedded with Digital Signal Processor (DSP) can be used to protect the system components as they can perform complex processing faster with higher accuracy and also avoid problem of false tripping. DSP based processing can also be optimized for real time. In this paper, TMS320F28335 based Implementation of Numerical Relay is discussed. TMS320F28335 is a floating point Digital Signal Controller (DSC). Short Time Fourier Transform (STFT) is used to detect the spurious signals and faults more accurately. The proposed overcurrent protection system is implemented on real time basis with the help of AntiAliasing filter and Signal Conditioning Circuit to scale the inputs from Current Transformer. Anti-Aliasing filter is designed based on the fault current simulation data generated using Power System Simulation Software. Fault current patterns generated are analyzed by calculating Fourier Transform coefficients that decide the filter specifications. Code Composer Studio (CCS) IDE is used for the development of algorithm. The paper discusses development of overcurrent protection algorithm based on RMS calculation for single phase circuits using TMS320F28335. The overcurrent relay Inverse Definite Minimum Time (IDMT) characteristics curves based on the simulated fault current data are used as basis and are implemented for Single Phase Circuits.