Control of Output and Circulating Current of Modular Multilevel Converter Using a Sliding Mode Approach

Uddin, Waqar; Zeb, Kamran; Khan, Muhammad Adil; Ishfaq, Muhammad; Khan, Imran; Islam, Saif ul; Kim, Hee-Je; Park, Gwan Soo; Lee, Cheewoo

doi:10.3390/en12214084

Cited by 32 publications

(21 citation statements)

References 44 publications

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“…Figure 11A(d) shows the circulating currents in the MMC legs, i cirσ . The circulating currents were calculated according to Equation (13) and they have an average value of 5 A. This small current component is important to accomplish the balance between the MMC SM voltages.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…From Equations (11) and (12), the circulating current that flows through the MMC legs can be expressed as in (13), which is composed by two main parts: the double fundamental frequency component of 100 Hz and its even order harmonic contents and a direct current (DC) component results from the DC-link currents [13].…”

Section: Deadbeat Predictive Current Controlmentioning

confidence: 99%

“…The magnitude of the circulating current has an influence on the MMC arm current. It increases the total root mean square (RMS) values of the MMC arm currents, which leads to extra power losses, and second-order harmonics will result in further generation of other higher-order harmonics, such as the 4th, 6th, 8th, etc., [13]. The circulating currents do not contribute to the MMC output currents synthesized by the power compensator, since the circulating currents flow only in the MMC arms [14].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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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.

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Section: Simulation Resultsmentioning

confidence: 99%

Section: Deadbeat Predictive Current Controlmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…In the context of electrochemical storage devices [19], in order to safeguard the cells and guarantee the highest number of charge/discharge cycles, it is necessary to keep all of the cells balanced in terms of their State of Charge (SoC). While traditional converters are normally equipped with an additional Battery Management System [20], MMC solutions inherently provide this balancing functionality at the module level [12,16,21,22].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Cell Loss Minimization in Modular Multilevel Converters Based on Half-Bridge Modules

et al. 2021

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In the developing context of distributed generation and flexible smart grids, in order to realize electrochemical storage systems, Modular Multilevel Converters (MMCs) represent an interesting alternative to the more traditional Voltage Source Inverters (VSIs). This paper presents a novel analytical investigation of electrochemical cell power losses in MMCs and their dependence on the injected common mode voltage. Steady-state cell losses are calculated under Nearest Level Control (NLC) modulation for MMCs equipped with a large number of half-bridge modules, each directly connected to an elementary electrochemical cell. The total cell losses of both a Single Star MMC (SS-MMC) and a Double Star MMC (DS MMC) are derived and compared to the loss of a VSI working under the same conditions. An optimum common mode voltage injection law is developed, leading to the minimum cell losses possible. In the worst case, it achieves a 17.5% reduction in cell losses compared to conventional injection laws. The analysis is experimentally validated using a laboratory prototype set-up based on a two-arm SS-MMC with 12 modules per arm. The experimental results are within 2.5% of the analytical models for all cases considered.

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“…Several studies have only focused on the linear model of a single MMC and, to some extent, ignored the dynamics of either DC or AC networks. In [26], a simplified model of an MMC is developed aiming for adopting a sliding mode control in abc-frame, which simplifies the complexity of the dq-frame transformation related to the MMC circulating current. The linear model of an MMC is derived for the system stability assessment in [6], and the control system is designed based on the linear model [27].…”

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confidence: 99%

Interaction Assessment and Stability Analysis of the MMC-Based VSC-HVDC Link

et al. 2020

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This paper investigates the dynamic behavior of a modular multi-level converter (MMC)-based HVDC link. An overall state-space model is developed to identify the system critical modes, considering the dynamics of the master MMC and slave MMC, their control systems, and the HVDC cable. Complementary to the state-space model, an impedance-based model is also derived to obtain the minimum phase margin (PM) of the system. In addition, a relative gain array (RGA) analysis is conducted to quantify the level of interactions among the control systems of master and slave MMCs and their impacts on stability. Finally, with the help of the results obtained from the system analysis (eigenvalue, phase margin, sensitivity, and RGA), the system dynamic performance is improved.3 of 19 an eigenvalue and participation factors analysis in Section 6. Moreover, the system minimum PM is calculated through an impedance-based analysis using the Nyquist plot, and the level of interactions among control loops is studied using a frequency-dependent relative gain array (RGA) analysis. Finally, in Section 7, based on the results achieved from the system analyses, the stability of the system is improved by tuning the DC voltage control loop. System DescriptionA typical HVDC link between two AC networks is shown in Figure 1. In such configuration, the master MMC regulates DC voltage while the slave MMC controls active power exchange [27]. Either AC voltage or reactive power can be regulated at both ends. AC network 1 HVDC cable AC network 2 Master Slave V dc control P control

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Control of Output and Circulating Current of Modular Multilevel Converter Using a Sliding Mode Approach

Cited by 32 publications

References 44 publications

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

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

Electrochemical Cell Loss Minimization in Modular Multilevel Converters Based on Half-Bridge Modules

Interaction Assessment and Stability Analysis of the MMC-Based VSC-HVDC Link

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