Objectives  The voltage of marine electrical equipment often fluctuates, but the existing stabilization schemes have low reliability and high cost. As such, distribution equipment that can operate in harsh environments is required to stabilize the voltage.

  Methods  This paper puts forward the design for a three-phase series voltage regulator based on a bidirectional thyristor and voltage regulator. It functions by controlling the magnitude and direction of voltage regulation through switching the bidirectional thyristor. Furthermore, the fault modes of the thyristor are analyzed and its fault diagnosis scheme obtained.

  Results  The results show that this design can realize the stabilization of only the output voltage by switching the bidirectional thyristor only according to the input voltage. when the H-bridge of the thyristor assembly breaks, it only affects the voltage regulation effects of the device. When the short-circuit thyristor of the high-voltage side of the transformer has an open-circuit fault, a large voltage or a large impact current is generated on its low voltage side, causing damage to the device. When the thyristor component has a short-circuit fault, if the equivalent is that the transformer does not compensate for the work, it has no effect on the device. If the equivalent is the short-circuit operation of the transformer, a large impact current may be generated in the entire circuit, causing damage to the device and electrical equipment.

  Conclusions  The voltage-regulating effects of this design are significant because it directly integrates the voltage-regulating transformer into the power supply circuit. With the more cost-effective bidirectional thyristor as an AC switch and the designed fault diagnosis technology, the reliability and service life of voltage regulating transformers can be improved.