Failure Prediction of Submodule Capacitors in Modular Multilevel Converter by Monitoring the Intrinsic Capacitor Voltage Fluctuations

Ronanki, Deepak; Williamson, Sheldon S.

doi:10.1109/tie.2019.2912771

Cited by 64 publications

(37 citation statements)

References 39 publications

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“…Therefore, C and ESR are dominated by low‐frequency and medium (switching) frequency components, respectively. The voltage across the SM capacitors is given by

V_{c x y h} = I_{c x y h} \cdot Z_{c x y h}

where

Z_{c x y h}

is an impedance of the AEC by neglecting ESL, which is given by

Z_{c x y h} = ES R_{c x y h} + normalj X_{c x y h}

The average voltage of the SM capacitor contains a second‐harmonic voltage component in addition to a steady‐state dc‐component [25]. Typically, the manufacturers give capacitance value of AEC at (second‐harmonic) 100 or 120 Hz.…”

Section: Proposed Balancing Control Strategymentioning

confidence: 99%

“…These approaches require complex algorithms to estimate the capacitance and are limited to a specific modulation scheme. In [25], the SM capacitance estimation is performed using band‐pass filters and root mean square (RMS) calculations to determine second‐harmonic impedance. Furthermore, the analysis is carried out at low‐frequency and high‐frequency modulation schemes.…”

Section: Introductionmentioning

confidence: 99%

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Submodule power balancing control of modular multilevel converters under capacitor degradation

Ronanki

Williamson

2020

IET power electron.

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“…Therefore, C and ESR are dominated by low‐frequency and medium (switching) frequency components, respectively. The voltage across the SM capacitors is given by

V_{c x y h} = I_{c x y h} \cdot Z_{c x y h}

where

Z_{c x y h}

is an impedance of the AEC by neglecting ESL, which is given by

Z_{c x y h} = ES R_{c x y h} + normalj X_{c x y h}

Section: Proposed Balancing Control Strategymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Submodule power balancing control of modular multilevel converters under capacitor degradation

Ronanki

Williamson

2020

IET power electron.

Self Cite

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“…Since component failure is inevitable in power electronic circuits operating over extended periods of time, protective measures must be taken to M. Asoodar (corresponding author), C. Danielsson, and R. Söderström are with Hitachi-ABB Power Grids, Sweden (email: asoodar@kth.se) M. Nahalparvari avoid stoppage of operation as a result of component failure. These protective measures are realized through additional protective hardware [6], or via health estimation of vulnerable components [7]. The focus of this paper is on creating a reliable protective measure for dc-link capacitors in MMCs through online estimation of their health state.…”

Section: Introductionmentioning

confidence: 99%

Online Health Monitoring of DC-Link Capacitors in Modular Multilevel Converters for FACTS and HVDC Applications

Asoodar

Nahalparvari

Danielsson

et al. 2021

IEEE Trans. Power Electron.

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This paper presents an online health monitoring scheme for dc capacitors in modular multilevel converters (MMCs). The health monitoring algorithm is based on detecting changes in the dc capacitance value over time. The proposed algorithm only utilizes measurements that are typically available in flexible alternating current transmission systems (FACTS) and high-voltage direct current (HVDC) applications. Hence, in the proposed estimation method, no additional sensors are used. The estimation scheme considers the presence of noise in voltage and current measurements, and utilizes a recursive least square (RLS) estimator in conjunction with a special low-pass filter to minimize the estimation errors. Simulation results of a hardware replica, as well as experimental results on a low-power MMC prototype show that the proposed scheme can identify the dclink capacitance value with a maximum error of 1%.

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“…Therefore, the safe operating region of the MMC is limited during such faults [4]. Moreover, the SM capacitors will deteriorate more quickly through the aging process if they are subjected to high voltage operation [5]. Aging gradually reduces their capacitance, and with aging the capacitor voltage will get even higher under unbalanced grid fault conditions.…”

Section: Introductionmentioning

confidence: 99%

Machine Learning Based Operating Region Extension of Modular Multilevel Converters Under Unbalanced Grid Faults

Wang

Dragičević

Gao

et al. 2021

IEEE Trans. Ind. Electron.

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The capacitor voltage ripples of the modular multilevel converter (MMC) are increased under unbalanced grid fault conditions. Since high capacitor voltage ripples deteriorate their lifetimes and may even cause tripping of the MMC system, it is important to restrict them. To this end, it is well known that injecting double fundamental frequency circulating currents can reduce the capacitor voltage ripples. However, finding a proper circulating current reference to achieve desired ripples analytically is complicated. This paper proposes an alternative method to quickly calculate the proper circulating current references without analytical computations, which is achieved by an artificial neural network (ANN) trained to approximate the relationship between circulating current references and capacitor voltage ripples. The training data is firstly extracted from a detailed simulation model of the MMC. Afterwards, the ANN is trained by the input-output data to obtain the mapping relationship, which is then used to derive the desired circulating current references. Both the simulation and the experimental results verify the practicability of the proposed method, where the operating region can be extended 30% at a minimum in all testing conditions.

show abstract

Failure Prediction of Submodule Capacitors in Modular Multilevel Converter by Monitoring the Intrinsic Capacitor Voltage Fluctuations

Cited by 64 publications

References 39 publications

Submodule power balancing control of modular multilevel converters under capacitor degradation

Submodule power balancing control of modular multilevel converters under capacitor degradation

Online Health Monitoring of DC-Link Capacitors in Modular Multilevel Converters for FACTS and HVDC Applications

Machine Learning Based Operating Region Extension of Modular Multilevel Converters Under Unbalanced Grid Faults

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