A Comparative Evaluation of Power Converter Circuits to Increase the Power Transfer Capability of High Voltage Transmission Lines

TL;DR

This paper compares two advanced power converter topologies, MMMC and BTB-MMC, to enhance power transfer in long high-voltage transmission lines by reducing transmission frequency, analyzing their design, efficiency, and fault tolerance.

Contribution

It provides a detailed analytical and simulation-based comparison of MMMC and BTB-MMC topologies for improving high-voltage transmission efficiency.

Findings

BTB-MMC requires fewer semiconductors.

Both topologies show different loss profiles.

Design equations facilitate topology optimization.

Abstract

AC transmission lines with lengths greater than 80km cannot be used to their maximum capacity due to limits in voltage drops and transient stability. This inefficient way of using conductors in a transmission line can be overcome if the electrical frequency at which energy is transmitted is reduced. This is why this work focuses on the comparison of the Modular Multilevel Matrix Converter (MMMC) and the Back-to-Back Modular Multilevel Converter (BTB-MMC), topologies that have shown qualities as frequency converters. For comparison, an analytical model of each topology is used to relate design considerations to their operational variables. Among the aspects to be compared are, the requirements of the semiconductors, the required reactive components, operating losses and fault tolerance. Detailed design equations, EMTP simulations, and comparison table are presented.