Energy-balancing Control Strategy for Modular Multilevel Converters Under Submodule Fault Conditions

Characteristic Analysis and Fault-Tolerant Control of Circulating Current for Modular Multilevel Converters under Sub-Module Faults

“…Though the reduced number of healthy SMs would cause the capacitor voltage be changed in the faulty arms, the SMs in the same arm also can operate with the same capacitor voltage with the voltage balancing control [14]. They can be expressed as:…”

“…It can achieve the suppression of unbalanced circulating current, but it needs positive-, negative-, and zero-sequence controllers simultaneously, and can only suppress the second-order frequency AC components of the circulating current. In [14], the energy-balancing fault-tolerant control mode is introduced. This method is easy to implement, which only needs to adjust the SM capacitor voltages on the faulty arms to ensure the energy equalization of each arm.…”

“…In addition, the basic mathematical model of MMC with redundant SMs is developed in this paper; however, the specific fault characteristics with different numbers of faulty SMs in each arm are not detailed enough, so the CCS control method is not considered. For solving this problem under the energy-balancing control mode [14], the CCS control techniques are researched in varying degrees in [15,16]. The single-phase vector control method based on virtual rotating coordinate frames is proposed in [15].…”

The Fault Detection, Localization, and Tolerant Operation of Modular Multilevel Converters with an Insulated Gate Bipolar Transistor (IGBT) Open Circuit Fault

“…Usually, depending on whether the redundant SMs are put into operation under the normal modes, the redundant modes can be categorized into the cold redundant mode [25,26] and hot redundant mode [27,28]. In the cold redundant mode, the redundant SMs are in the bypass state under normal cases and they are in the operational modes only when faults happen.…”

A Transient Fault Recognition Method for an AC-DC Hybrid Transmission System Based on MMC Information Fusion

“…MMC based on insulated gate bipolar transistor (IGBT) is a new technology that is widely used in voltage-source converters [2,3]. As a new HVDC technology, MMC-HVDC introduces fully controlled power electronics devices and PWM technology, and solves many problems that exist in conventional HVDC [4][5][6][7][8]. Large amounts of researches have been conducted on MMC-HVDC, so it widely applies in many areas such as the large-capacity power delivery, asynchronous networks and island power transmission [9][10][11][12].…”