Dynamic Performance Analysis of Long-distance Power Transmission System with DC Superconducting Cable from Large Photovoltaic Generation

This paper proposes a new long-distance power transmission system with superconducting cable fromlarge-scale photovoltaic (PV) power generation alongwith the dynamic performance analysis. The advantage of the proposed system is the reduction in the ac/dc conversion steps compared with the conventional one. As is well known, long-distance power transmission requires a dc system, and conventional dc power transmission system requires high dc voltage with low current to reduce losses. Such a high voltage has been achieved by dc/ac conversion with a boost chopper and an inverter from PV, and ac/dc conversion by a rectifier to dc cable. On the other hand, superconducting cable can transmit power with a lower voltage and higher current compared with conventional cable. This enables us to convert the dc voltage from PV plant to dc voltage to superconducting cable directly. Furthermore, the capacitance of the superconducting cable could be used for stable dc operation. In this paper, the system configuration, operation steps, controls, and characteristics verified by computer simulation are presented; eXpandable Transient Analysis Program (XTAP) is used for the simulation.