Implementation and Performance Evaluation of Diode Failure Detection Algorithm of Diode Failure Detection Relay for Brushless Excitation System

Brushless Excitation Systems have been widely used in Synchronous Generators as it reduces the losses, maintenance and improves the reliability of the system by eliminating the usage of commutator, brushes and slip rings. Rotating diode bridge rectifier is the main part of brushless excitation system. Due to aging phenomenon and continuous process regime, the diode in the rotating bridge rectifier can fail either due to open circuit or short circuit. If such a failure prolonged, the Automatic Voltage Regulator (AVR) as well as the Exciter winding can be damaged. This paper briefly describes the structure of Brushless Excitation System technology and its operation. The paper presents the modeling of Brushless Excitation System in Real Time Digital Simulator (RTDS) and simulations carried out to study the behavior of system during the diode open circuit condition and short circuit condition in a rotating bridge rectifier. It describes the technique/principle established for detecting a diode failure condition and its validation using RTDS. It also describes the suitable hardware architecture consisting of Field Programmable Gate Array (FPGA) & Processor module chosen to implement the developed diode failure detection algorithm. The paper summarizes the implementation of developed algorithm on hardware and the performance evaluation carried out through Hardware-In-Loop (HIL) testing using RTDS. It also presents the various tests carried out to evaluate the performance of developed detection relay on test bed of Brushless Excitation System.