Research on active damping voltage control considering leakage inductance of FOVRT transformer

• Flexible on-load voltage regulating transformer achieve continuous voltage regulation through tap changers and converters. • By analyzing various damping controls, an active damping control strategy based on capacitive current is proposed. • Delay compensation and PR control schemes were proposed, and the influence of parameter variations was investigated. • The leakage inductance of the transformer is utilized to reduce the cost and volume of the system. The Flexible on-load voltage regulating transformer (FOVRT) is realized through the integration of a small power converter with the conventional on-load voltage regulator transformer. This amalgamation enables the transition from the traditional “step-type voltage regulation” to “continuous voltage regulation” by synergizing tap-changing regulation and converter output voltage. In this study, the leakage inductance of the transformer, which is connected in series with the converter within the FOVRT, necessitates the configuration of an LCL type converter topology. The control target is the converter output voltage, for which an active damping control strategy, predicated on capacitive current feedback, is proposed. A static model of the FOVRT converter is developed, and following a comprehensive comparison of various damping methods, pertinent damping solutions are advanced, complemented by corresponding delay compensation and PR control schemes. Furthermore, the influence of control parameter variations on system control performance is meticulously analyzed. A distinguishing feature is the consideration of transformer leakage inductance for FOVRT. A reasonable resonance control and damping control are introduced through the damping scheme analysis. The resonance caused by transformer leakage inductance is effectively suppressed. Both simulation and experimental results substantiate the efficacy of the proposed control strategy.