Loss Optimization of MMC by Second-Order Harmonic Circulating Current Injection

Yang, Limin; Li, Yaohua; Li, Zixin; Wang, Ping; Xu, Shukai; Gou, Ruifeng

doi:10.1109/tpel.2017.2751068

Cited by 63 publications

(53 citation statements)

References 24 publications

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“…As it can be observed from the figure, the losses are decreased by more than 10% (and up to 16% in the first two reactive power amounts) due to mitigation of circulating current. This is while most recent studies in this field are suggesting less than 10% reductions in converter losses, using various second harmonic current control approaches [35,36]. Therefore, MMC loss evaluations provided in Figure 11 confirm that the proposed method can effectively improve converter operation in power loss terms, as well.…”

Section: Gate Signalssupporting

confidence: 55%

“…Given that i gd = i Ld − i d and i gq = i Lq − i q , we can substitute Equations (37) and (38) into (36), which leads to:…”

Section: Maximum Stable Operation Rangementioning

confidence: 99%

“…Equation (39) has been developed based on converter power capacity equations represented in (36). Therefore, the equation represents current (and thus power) margins of the MMC in a stable operation mode based on converter and grid parameters.…”

Section: Maximum Stable Operation Rangementioning

confidence: 99%

See 2 more Smart Citations

Control of MMC-Based STATCOM as an Effective Interface between Energy Sources and the Power Grid

Shahnazian

Adabi

et al. 2019

Electronics

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This paper presents a dynamic model of modular multilevel converters (MMCs), which are considered as an effective interface between energy sources and the power grid. By improving the converter performance, appropriate reactive power compensation is guaranteed. Modulation indices are calculated based on detailed harmonic evaluations of both dynamic and steady-state operation modes, which is considered as the main contribution of this paper in comparison with other methods. As another novelty of this paper, circulating current control is accomplished by embedding an additional second harmonic component in the modulation process. The proposed control method leads to an effective reduction in capacitor voltage fluctuation and losses. Finally, converter’s maximum stable operation range is modified, which provides efficiency enhancements and also stability assurance. The proficiency and functionality of the proposed controller are demonstrated through detailed theoretical analysis and simulations with MATLAB/Simulink.

show abstract

Section: Gate Signalssupporting

confidence: 55%

“…Given that i gd = i Ld − i d and i gq = i Lq − i q , we can substitute Equations (37) and (38) into (36), which leads to:…”

Section: Maximum Stable Operation Rangementioning

confidence: 99%

See 1 more Smart Citation

Control of MMC-Based STATCOM as an Effective Interface between Energy Sources and the Power Grid

Shahnazian

Adabi

et al. 2019

Electronics

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show abstract

“…Different types of converter topologies, containing the traditional two-level converter, multi-module converter, multilevel converter, and the newly recently advanced modular multilevel converter (MMC), have been presented and studied for battery storage converter applications [9][10][11][12][13]. Amid all the topology structures, the MMC is a recommended topology due to its merits such as 2 of 19 high quality of the output voltage, flexible scaling of sub-modules (SMs), bidirectional power flow, and independent regulation of the active and reactive power [14,15]. These inherently salient features make the MMC ideally suited for battery energy storage systems.…”

Section: Introductionmentioning

confidence: 99%

Disturbance-Observer-Based Model Predictive Control for Battery Energy Storage System Modular Multilevel Converters

et al. 2018

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Although the traditional model predictive control (MPC) can theoretically provide AC current and circulating current control for modular multilevel converters (MMCs) in battery energy storage grid-connected systems, it suffers from stability problems due to the power quality of the power grid and model parameter mismatches. A two discrete-time disturbance observers (DOBs)-based MPC strategy is investigated in this paper to solve this problem. The first DOB is used to improve the AC current quality and the second enhances the stability of the circulating current control. The distortion and fluctuation of grid voltage and inductance parameter variation are considered as lump disturbances in the discrete modeling of a MMC. Based on the proposed method, the output prediction is compensated by disturbance estimation to correct the AC current and circulating current errors, which eventually achieve the expected tracking performance. Moreover, the DOBs have a quite low computational cost with minimum order and optimal performance properties. Since the designed DOBs work in parallel with the MPC, the control effect is improved greatly under harmonics, 3-phase unbalance, voltage sag, inductance parameter mismatches and power reversal conditions. Simulation results confirm the validity of the proposed scheme.

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“…Zhang et al [25] simplified the switching function into a continuous change rate function, and computational efficiency was further increased by replacing part of the detailed calculation by estimated upper limits. Yang et al [26] derived a loss model with linear fitting method applied to the relationship between the loss and the current of semiconductors. In the existing literatures, losses are usually estimated by introducing the concept of probability and average.…”

Section: Introductionmentioning

confidence: 99%

Semiconductor loss calculation of DC–DC modular multilevel converter for HVDC interconnections

Zhao

Chen

2018

High Voltage

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DC-DC modular multilevel converter (DC-DC MMC) is an attractive candidate for high-voltage DC (HVDC) interconnections since it can provide the required voltage matching, galvanic isolation and flexible power control abilities. The semiconductor loss of such a DC-DC MMC is a major concern for both system evaluation and parameter design. However, it cannot be measured directly since it is out of the precision range of the high-voltage measuring equipment, and thus, mathematical analysis is considered as a feasible alternative. This paper proposes an accurate off-line loss calculation method for DC-DC MMC modulated by fundamental frequency modulation. Based on the characteristics of the modulation, the switching moments along with the instantaneous voltage and current can be calculated exactly, and the conduction loss and switching loss of each submodule can be expressed in a mathematical way. The calculation results are compared with the simulation results from a comprehensive switched model and show good accuracy performance within a relative error of ± 2% under different operating conditions.

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Loss Optimization of MMC by Second-Order Harmonic Circulating Current Injection

Cited by 63 publications

References 24 publications

Control of MMC-Based STATCOM as an Effective Interface between Energy Sources and the Power Grid

Control of MMC-Based STATCOM as an Effective Interface between Energy Sources and the Power Grid

Disturbance-Observer-Based Model Predictive Control for Battery Energy Storage System Modular Multilevel Converters

Semiconductor loss calculation of DC–DC modular multilevel converter for HVDC interconnections

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