Deadbeat Predictive Current Control for Circulating Currents Reduction in a Modular Multilevel Converter Based Rail Power Conditioner

Abstract

This paper presents a deadbeat predictive current control methodology to reduce the circulating currents in a modular multilevel converter (MMC) when it operates as a rail power conditioner (RPC) in a conventional railway system-based V/V connection. For this purpose, a half-bridge MMC based on half-bridge submodules, operating as an RPC is explained, and the total system is denominated as a simplified rail power conditioner (SRPC). The SRPC in this study is used to compensate harmonics, reactive power, and the negative sequence component of currents. This paper explains the SRPC system architecture, the key control algorithms, and the deadbeat predictive current control methodology. Mathematical analysis, based on the MMC equivalent circuit, is described and the reference equations are presented. Moreover, simulation results of the deadbeat predictive current control methodology are compared with the results of the conventional proportional-integral (PI) controller. This comparison is to verify the effectiveness of the proposed control strategy. Simulation results of the SRPC show reduced circulating currents in the MMC phases when using the predictive control approach, besides accomplishing power quality improvement at the three-phase power grid side.

Submodule Topologies and PWM Techniques Applied in Modular Multilevel Converters: Review and Analysis

“…The biggest implementation challenges based on this topology lies essentially in balancing the DC-link voltage of each submodule. In this context, deadbeat predictive current control methodology to reduce the circulating currents and balancing the submodule voltages in the MMC is presented in [11]. Moreover, each submodule will contribute to a portion of the total power, which causes currents circulating in the submodules.…”

Topologies and Operation Modes of Rail Power Conditioners in AC Traction Grids: Review and Comprehensive Comparison

“…Nowadays, the majority of the commercial MMC projects are based on the indirect AC/DC/AC MMC with half-bridge SMs [54]. This is due to the high efficiency of the half-bridge SM, besides its lower cost and simpler construction comparing to other types of SM [55].…”

“…Each half-bridge SM contains two switching devices and one capacitor that can be inserted or bypassed. The arm inductors are important to adjust the circulating current value between the MMC legs (the circulating currents are produced due to the inner DC-voltage differences between the MMC SMs [55]). In this topology, ITs with a turns ratio 1:1 are necessary to interface between the converter and the traction power grid.…”

New Multifunctional Isolated Microinverter with Integrated Energy Storage System for PV Applications

“…For a small sampling period, Ts, it can be considered that the variation of ierror, is almost constant. Additionally, it can be concluded that the effectiveness of this control technique is directly influenced by the quality of the considered system model [31].…”

“…Additionally, it can be concluded that the effectiveness of this control technique is directly influenced by the quality of the considered system model [31]. By analyzing Figure 7, it is possible to perceive the existence of two input control algorithm blocks: MPPT Control and BESS Control.…”