Short-circuit current capability for remote power control of a stand-alone variable-speed generation set

The paper presents variable-speed generation system. A diesel engine drives as axial flux permanent magnet generator. The variable amplitude and frequency generator voltage is converted to three phase AC50 Hz/400 V. The system has to cope with short-circuit events. A new method of thyristor bypass, connecting high frequency generator voltage and low frequency output voltage, is proposed. Thyristor asynchronous by-pass connects the generator with output and is capable to cope with much higher currents than transistor. The high current of the circuit, made from permanent magnet generator and thyristor by-pass, results in trip action of the circuit breaker. Such arrangement provides generation system with safe protection without oversizing transistor converter. As the generator is applied a axial flux permanent magnet generator with high short circuit current. Results of theoretical considerations are confirmed by experimental laboratory results of 40 kVA generating set.