Detection of Rotating Diode Failure Condition & its Protection in Brushless Alternator

  • Authors

    • Pranupa S
    • Kiran Kumar B M
    • S. Nagaraja Rao
  • Brushless excitation system is widely used in large capacity synchronous generators since it removes the usage of commutator, brushes and slip rings, hence reduces the losses, maintenance and increases reliability. Rotating Rectifier Assembly (RRA) is the main part of brushless alternator. Due to ageing phenomenon and continuous process regime, diodes in rotating rectifier can fail either due to Open Circuit (OC) or Short Circuit (SC), which overloads the exciter and hence the alternator can no longer run securely. If such condition is prolonged, the Automatic Voltage Regulator (AVR) as well as the exciter windings can be damaged.

    This paper presents two different methods of diode failure detection in brushless alternators. First method uses an algorithm based on output voltage and the second uses the ripple factor of the exciter field current. Diode failure condition is detected for different type of loads connected to 4 kVA, 380 V, 50 Hz, 4 poles generator with 14 pole exciter (brushless alternator) and the results are verified using MATLAB/Simulink. Also, the protection schemes for rotating diode assembly as well as exciter field windings are presented using Metal Oxide Varistor (MOV) and Discharge Resistor.

  • References

    1. [1] Zouaghi, T., &Poloujadoff, M. (1998). Modeling of polyphase brushless exciter behavior for failing diode operation. IEEE transactions on energy conversion, 13(3), 214-220.

      [2] Batzel, T. D., Swanson, D. C., &Defenbaugh, J. F. (2003, August). Predictive diagnostics for the main field winding and rotating rectifier assembly in the brushless synchronous generator. In Diagnostics for Electric Machines, Power Electronics and Drives, 2003. SDEMPED 2003. 4th IEEE International Symposium on (pp. 349-354). IEEE

      [3] Sottile, J., Trutt, F. C., &Leedy, A. W. (2006). Condition monitoring of brushless three-phase synchronous generators with stator winding or rotor circuit deterioration. IEEE Transactions on Industry Applications, 42(5), 1209-1215.

      [4] Salah, M., Bacha, K., Chaari, A., &Benbouzid, M. E. H. (2014). Brushless three-phase synchronous generator under rotating diode failure conditions. IEEE Transactions on Energy Conversion, 29(3), 594-601.

      [5] Salah, M., Bacha, K., &Chaari, A. (2013, March). Detection of brushless exciter rotating diodes failures by spectral analysis of main output voltage. In Electrical Engineering and Software Applications (ICEESA), 2013 International Conference on (pp. 1-6). IEEE.

      [6] Na, W. (2011, July). A feedforward controller for a brushless excitation system during the diode open circuit fault operation. In Power and Energy Society General Meeting, 2011 IEEE(pp. 1-4). IEEE.

      [7] McArdle, M. G., & Morrow, D. J. (2004). Noninvasive detection of brushless exciter rotating diode failure. IEEE Transactions on Energy Conversion, 19(2), 378-383.

      [8] Gray, D., Zhang, Z., Apostoaia, C., & Xu, C. (2009, June). A neural network based approach for the detection of faults in the brushless excitation of a synchronous motor. In Electro/Information Technology, 2009. eit'09. IEEE International Conference on (pp. 423-428). IEEE.

      [9] Rahnama, M., &Vahedi, A. (2016, January). Rotary diode failure detection in brushless exciter system of power plant synchronous generator. In Thermal Power Plants (CTPP), 2016 6th Conference on (pp. 6-11). IEEE.

      [10] Bui, H. K., Bracikowski, N., Hecquet, M., Zappellini, K. L., &Ducreux, J. P. (2017). Simulation of a large power Brushless Synchronous Generator (BLSG) with a rotating rectifier by a reluctance network for fault analysis and diagnosis. IEEE Transactions on Industry Applications, 53(5), 4327-4337.

  • Downloads

  • How to Cite

    S, P., B M, K. K., & Rao, S. N. (2018). Detection of Rotating Diode Failure Condition & its Protection in Brushless Alternator. International Journal of Engineering & Technology, 7(4.24), 26-32.