Abstract: A voltage source type direct-current ice melting apparatus, a flexible interconnection system and a control method are provided. The voltage source type direct-current ice melting apparatus includes a starting unit, a modular multi-level converter and a measurement control unit. The flexible interconnection system includes two voltage source type direct-current ice melting apparatuses having the same circuit structure. The measurement control unit acquires set values, that are input by a user, of relevant parameters and then processes the set values, that are input by the user, of the relevant parameters and measured values, measured in real time by the measurement control unit, of the relevant parameters, thereby determining and sending a control signal, so as to control an operating state of the modular multi-level converter in the apparatus or system.

Abstract: A modeling method and system for a diode clamped cascaded multi-level converter. All corresponding diodes of each bridge arm are equivalent to an auxiliary diode; all corresponding capacitors of each bridge arm are equivalent to a controlled voltage source; and power modules of each bridge arm are connected in series to be equivalent to an equivalent module, the equivalent module comprising a loss resistor and a composite equivalent model connected to the loss resistor. Since a plurality of components, at the same positions, in each power module of each bridge arm of the diode clamped cascaded multi-level converter are equivalent to a component, the node voltage equation order can be reduced, the simulation efficiency is improved, and the simulation efficiency cannot be reduced with the increase in the number of power modules.