An Adaptive Total Sliding Mode Control for Cascaded H-bridge Multilevel Converters to Flexibly Suppress Ground Fault Arcs in Active Distribution Networks

Single phase-to-ground (SPG) faults are the most common faults in active distribution networks, which can cause hazardous situations and consequences, such as fires, electric shocks, and power outages. Power electronic converters using typical control methods, like proportional-integral (PI) control, backstepping control (BSC), and sliding mode control (SMC), can suppress the fault current and voltage until the fault arc disappears. However, these controllers are not adaptable to the various fault resistances and have long transient DC bias decay processes, resulting in the arc not being suppressed quickly and reliably. This paper proposes a novel adaptive total sliding mode control (ATSMC) for cascaded H-bridge multilevel converters (CHMC) to not only adapt to the uncertain and various fault resistances with a wide range but also eliminate the long-term transient DC bias decay processes, and the steady-state residual fault current and voltage can be suppressed to be smaller. The proposed method satisfies Lyapunov's asymptotic stability and is also applicable to other power electronic converter topologies for suppressing fault arcs. The simulation study and experimental validation demonstrate the effectiveness of the proposed method in providing the above advantages and exhibit better overall performance, compared to those of PI, BSC, and SMC.