Multi-port Converter for Medium and High Voltage Applications

Abstract

This work presents a multi-port converter (MPC) that is well-suited for use as a hybrid hub in complex multiterminal high-voltage direct current (MTDC) networks. The proposed MPC generates several and controllable DC voltages from a constant or variable input DC voltage or AC grid. Its operating principle is explained and corroborated using simulations and experimentations.

Review of technologies for DC grids – power conversion, flow control and protection

“…Partially isolated dc–dc converter in [67, 68, 93] is attractive economically as it permits the transformer in its ac link and sub‐converters to be fractionally rated. Its multi‐port version that generates multiple and independent dc and ac voltages are attractive for the complex hub that facilitates dc and ac voltage tapping and matching and power control, with the bespoke ability to precisely define the route of the power flow from a given input to a given output [93, 94]. The non‐isolated MMC and HC two‐level dc–dc converters in [69, 95] offer a cost‐effective solution for dc voltage matching between two dc systems with common ground. Series current flow controllers : Fractionally rated bidirectional interline current or power flow controllers in [71, 73–77] offer low cost solutions for controlling and rerouting dc currents or dc powers within the dc grids away from the bottlenecks and over‐loaded dc cables; thus, these devices are expected to play major roles in large dc grids that include floating dc nodes. DCCBs: Section 6 reviews a number of basic DCCB technologies, covering fault isolation time scales ranging from 2 to 15 ms.…”

“…Non-isolated F2F dc-dc converters are unable to prevent pole-shifting during pole-to-ground dc fault and suffer from high losses and poor utilization of the semiconductor of the high-voltage converter, therefore, not viable for dc grids. Partially isolated dc-dc converter in [68,69,91] is attractive economically as it permits the transformer in its ac link and sub-converters to be fractionally rated. Its multi-port version that generates multiple and independent dc and ac voltages is attractive for complex hub that facilitates dc and ac voltage tapping and matching and power control, with bespoke ability to precisely define the route of the power flow from a given input to a given output [91,92].…”

“…Partially isolated dc-dc converter in [68,69,91] is attractive economically as it permits the transformer in its ac link and sub-converters to be fractionally rated. Its multi-port version that generates multiple and independent dc and ac voltages is attractive for complex hub that facilitates dc and ac voltage tapping and matching and power control, with bespoke ability to precisely define the route of the power flow from a given input to a given output [91,92]. The non-isolated MMC and hybrid cascaded two-level dc-dc converters in [70,93] offer cost-effective solution for dc voltage matching between two dc systems with common ground.…”