Estimation Methods and Sensor Reduction in Modular Multilevel Converters: A Review

Konstantinou, Georgios; Wickramasinghe, Harith R.; Townsend, Christopher D.; Ceballos, Salvador; Pou, Josep

doi:10.1109/icpesys.2018.8626987

Cited by 18 publications

(6 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The number of SMs per stack depends on the voltage of the application. In a typical HVDC application, the number of SMs per stack can be over 500 [6], with a voltage of ±400 kV. On the other hand, motor drive applications need between 5 − 20 SMs for an operating voltage of 3.3 − 13.8 kV [9].…”

Section: B Modular Multilevel Convertersmentioning

confidence: 99%

“…A second challenge comes from the fact that the modular structure of the MMC is not exploited in the control scheme, which usually is centralized and requires a large number of measurements and signals, including at least one voltage measurement per each SM. This increases the complexity and cost of the converter, and reduces reliability and noise tolerance [6]. Several efforts have been made to reduce the number of voltage sensors in MMCs, in order to simplify the hardware requirements and increase reliability and noise immunity [6].…”

Section: Introductionmentioning

confidence: 99%

“…This increases the complexity and cost of the converter, and reduces reliability and noise tolerance [6]. Several efforts have been made to reduce the number of voltage sensors in MMCs, in order to simplify the hardware requirements and increase reliability and noise immunity [6]. The Kalman filter has been proposed as an estimator for capacitor voltage in [7], but the formulation uses an extra voltage sensor per stack and its slow dynamic response may affect control performance during transients and faults.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Denoising and Voltage Estimation in Modular Multilevel Converters Using Deep Neural-Networks

et al. 2020

View full text Add to dashboard Cite

Modular Multilevel Converters (MMCs) have become one of the most popular power converters for medium/high power applications, from transmission systems to motor drives. However, to operate properly, MMCs require a considerable number of sensors and communication of sensitive data to a central controller, all under relevant electromagnetic interference produced by the high frequency switching of power semiconductors. This work explores the use of neural networks (NNs) to support the operation of MMCs by: i) denoising measurements, such as stack currents, using a blind autoencoder NN; and ii) estimating the sub-module capacitor voltages, using an encoder-decoder NN. Experimental results obtained with data from a three-phase MMC show that NNs can effectively clean sensor measurements and estimate internal states of the converter accurately, even during transients, drastically reducing sensing and communication requirements. INDEX TERMS Modular multilevel converters, neural networks, cyber-physical systems.

show abstract

Section: B Modular Multilevel Convertersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Denoising and Voltage Estimation in Modular Multilevel Converters Using Deep Neural-Networks

et al. 2020

View full text Add to dashboard Cite

show abstract

“…With the reduction of the amount of SM voltage sensors in the MMC, the cost and complexity of the MMC data acquisition stages can be decreased. However, designing an algorithm to decrease the voltage measurement errors becomes a challenge [23] and the measurement error reduction in NLM-based SM capacitor voltage measuring technology of MMC with reduced voltage sensors is few.…”

Section: Introductionmentioning

confidence: 99%

An Improved Submodule Capacitor Voltage Measuring Algorithm for MMC With Reduced Sensors

Liu

Teodorescu

et al. 2021

IEEE Sensors J.

View full text Add to dashboard Cite

The nearest level modulation (NLM) based submodule capacitor voltage measuring technology for a modular multilevel converter (MMC) with reduced sensors can effectively reduce the costs of the data acquisition system of MMC and simplify the operation system. One of the technical challenges of this submodule capacitor voltage measuring technology is to reduce the measurement errors of submodule capacitor voltage. This paper proposes an improved submodule capacitor voltage measuring algorithm to overcome this challenge. In the proposed algorithm, by keeping the operation states of submodules unchanged during the continuous control period, the probability of obtaining the actual capacitor voltage is increased, and then the number of corrections of observed capacitor voltage is significantly increased. Thus, the proposed algorithm can effectively reduce the measuring errors. More significantly, the proposed algorithm can also improve the measurement accuracy even in the capacitance deviation situation. Finally, both simulation and experimental results are provided to verify the feasibility and effectiveness of the proposed voltage measuring algorithm.

show abstract

“…There are two capacitors in the UDSSM, and normally a voltage sensor is required for each capacitor to implement capacitor voltage balancing control. The voltage sensor of the capacitors plays a significant role to the reliability of the MMC system since not only the voltage balancing control but also the protection of the submodules is related [24]. Based on the redundancy of two voltage sensors in the UDSSM, the capacitor voltage balancing control under malfunction of the voltage sensor would be researched in this paper.…”

Section: Introductionmentioning

confidence: 99%

Unipolar Double-Star Submodule for Modular Multilevel Converter With DC Fault Blocking Capability

Zhu

Zhang

et al. 2019

IEEE Access

View full text Add to dashboard Cite

Adopting overhead lines is an effective way to reduce the cost of flexible high voltage direct current (HVDC) systems. However, the dc short-circuit fault is easily occurred and the development of the overhead lines based HVDC system is hampered. This paper proposes a unipolar double-star submodule (UDSSM) with the dc fault blocking capability. Under the dc fault condition, the UDSSM based modular multilevel converter (MMC) could block the fault current by switching all power switching devices off to protect the MMC system. In each proposed submodule, two capacitors work under almost the same condition and could be in series or parallel connection to output different voltage levels. Then two voltage sensors of the two capacitors are redundant each other, which improves the reliability of the MMC system. Additionally, voltage balancing methods for the capacitors under both normal operation and sensor fault conditions of the MMC submodule are developed in this paper. The effectiveness of the proposed submodule and the capacitor voltage balancing strategy are validated by the simulation and experiment results.INDEX TERMS Capacitor voltage balancing, dc fault blocking, HVDC, MMC, submodule topology.

show abstract

Estimation Methods and Sensor Reduction in Modular Multilevel Converters: A Review

Cited by 18 publications

References 33 publications

Denoising and Voltage Estimation in Modular Multilevel Converters Using Deep Neural-Networks

Denoising and Voltage Estimation in Modular Multilevel Converters Using Deep Neural-Networks

An Improved Submodule Capacitor Voltage Measuring Algorithm for MMC With Reduced Sensors

Unipolar Double-Star Submodule for Modular Multilevel Converter With DC Fault Blocking Capability

Contact Info

Product

Resources

About