Design & Simulation of DSP based 24 kA Thyristor Controlled Rectifier for Nuclear Reactor Safety Study

Experimental research and development facilities pertaining to safety of nuclear power plant utilizes simulated nuclear fuel clusters for conducting innovative research studies to understand the effect of power/temperature transients on nuclear fuel channel during accidental as well as normal situations. Powering those transients in an experimental facility is performed by electrical heating analogous to nuclear fission heating by current/power controlled high current through high power rectifiers. The desired power/temperature profile can be obtained by controlling the set reference current/power of the phase angle controlled thyristor rectifier system regardless of input voltage and load resistance variations. The paper presents design and performance simulation of digital signal processor based 12-pulse 24 kA, 90 volts thyristor controlled rectifier powering nuclear fuel cluster simulators. Design parameter including cooling requirements of rectifier transformer, inter phase reactor and thyristor assemblies have been described in the paper. The digital controller incorporated in the design is a TI DSP TMS320F28335, for low voltage high current application in close feedback loop system. The thyristor controlled rectifier has been designed to operate either in constant current mode or in constant power mode. Besides, the provision has been made in the design such that rectifier can be operated individually delivering six pulse output as well as in parallel delivering twelve pulse output for high DC current supply to fuel cluster simulators. The performance simulation results highlighting waveforms of various electrical parameters has been presented for demonstration of design validation.