GaN‐Based Three‐Phase Voltage and Current Sources for Power Relay Testing

This paper implements low‐cost GaN‐based three‐phase voltage and current sources to validate power protecting relays. This proposal develops a voltage generator that uses three single‐phase full‐bridge converters equipped with an LC filter and an isolating transformer. It also includes a current generator using three single‐phase half‐bridge converters furnished with an LCL filter. Both voltage and current testing sources are assembled employing GaN transistor technology, which enables operation at high switching frequencies and passive filters with low‐value components. Experimental tests are conducted to confirm and validate the operation and dynamic performance of voltage and current testing sources. Finally, the performance of the voltage and current signal generator is assessed by testing a commercial protection system (SEL‐451) through directional current function. This is achieved by emulating a fault condition, where three voltage and current signals are generated to trigger the trip signal after surpassing the relay threshold.