scholarly journals Assessment of Sequence Extraction Methods Applied to MMC-SDBC STATCOM Under Distorted Grid Conditions

2021 ◽  
Author(s):  
Taoufik QORIA ◽  
Ahmed Meligy ◽  
Ilknur Colak
Keyword(s):  
Control Strategies ◽  
Critical Role ◽  
Extraction Methods ◽  
Current Control ◽  
Positive Sequence ◽  
Stable Operation ◽  
Multilevel Converters ◽  
Synchronous Reference Frame ◽  
Distorted Grid ◽  
Stability Dynamics

Under grid distortions, Modular Multilevel Converters (MMC) must adopt proper control strategies to fulfill the power system requirements and ensure a stable operation. An inappropriate control under such conditions may lead to energy unbalances between the MMC legs, inaccurate current injection, and failure in the synchronization process. In this context, sequence extraction methods play a critical role in enhancing the performance of the control, firstly, by aiding the Phase-Locked Loop (PLL) to maintain the synchronization with the AC grid by following the positive sequence fundamental component of the voltage, secondly, by allowing an accurate active and reactive currents injection via the decoupled Voltage Oriented Control (dVOC), thirdly, by properly managing the internal energy of the MMC through the circulating current control. In prior researches, some sequence extraction methods have been used for MMC STATCOM. However, the sequence extraction was not the core of the performed studies and their impact on the system behavior has not been highlighted or tested in several grid conditions. This work fills this gap by first assessing the performance of a Single Delta Bridge Cell MMC (SDBC-MMC) STATCOM with four well-known sequence extraction methods (i.e., Decoupled Double Synchronous Reference Frame (DDSRF), Dual Second Order Generalized Integrator (DSOGI), Improved DSOGI, and Fortescue matrix-based (FMB) filter) under normal and abnormal grid conditions, then, finding the most suitable one in terms of stability, dynamics, and functionalities.

scholarly journals Assessment of Sequence Extraction Methods Applied to MMC-SDBC STATCOM Under Distorted Grid Conditions

2021 ◽  
Author(s):  
Taoufik QORIA ◽  
Ahmed Meligy ◽  
Ilknur Colak
Keyword(s):  
Control Strategies ◽  
Critical Role ◽  
Extraction Methods ◽  
Current Control ◽  
Positive Sequence ◽  
Stable Operation ◽  
Multilevel Converters ◽  
Synchronous Reference Frame ◽  
Distorted Grid ◽  
Stability Dynamics

Under grid distortions, Modular Multilevel Converters (MMC) must adopt proper control strategies to fulfill the power system requirements and ensure a stable operation. An inappropriate control under such conditions may lead to energy unbalances between the MMC legs, inaccurate current injection, and failure in the synchronization process. In this context, sequence extraction methods play a critical role in enhancing the performance of the control, firstly, by aiding the Phase-Locked Loop (PLL) to maintain the synchronization with the AC grid by following the positive sequence fundamental component of the voltage, secondly, by allowing an accurate active and reactive currents injection via the decoupled Voltage Oriented Control (dVOC), thirdly, by properly managing the internal energy of the MMC through the circulating current control. In prior researches, some sequence extraction methods have been used for MMC STATCOM. However, the sequence extraction was not the core of the performed studies and their impact on the system behavior has not been highlighted or tested in several grid conditions. This work fills this gap by first assessing the performance of a Single Delta Bridge Cell MMC (SDBC-MMC) STATCOM with four well-known sequence extraction methods (i.e., Decoupled Double Synchronous Reference Frame (DDSRF), Dual Second Order Generalized Integrator (DSOGI), Improved DSOGI, and Fortescue matrix-based (FMB) filter) under normal and abnormal grid conditions, then, finding the most suitable one in terms of stability, dynamics, and functionalities.

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

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1264 ◽  
Author(s):  
Fatemeh Shahnazian ◽  
Ebrahim Adabi ◽  
Jafar Adabi ◽  
Edris Pouresmaeil ◽  
Kumars Rouzbehi ◽  
...  
Keyword(s):  
Reactive Power ◽  
Control Method ◽  
Second Harmonic ◽  
Power Grid ◽  
Harmonic Component ◽  
Current Control ◽  
Energy Sources ◽  
Stable Operation ◽  
Multilevel Converters ◽  
Steady State Operation

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.

scholarly journals The Control Reversing Algorithm for Autonomous Vehicles with PSD-Controlled Trailers

2021 ◽  
Vol 24 (4) ◽  
pp. 187-194
Author(s):  
Vladimír Cviklovič ◽  
Rastislav Srnánek ◽  
Dušan Hrubý ◽  
Marta Harničárová
Keyword(s):  
Mathematical Model ◽  
Autonomous Vehicles ◽  
Dynamic Models ◽  
Control Strategies ◽  
Current Control ◽  
Autonomous Control ◽  
Stable Operation ◽  
Velocity Control ◽  
Computing Power ◽  
The Subject

Abstract Driving a vehicle with a passive trailer has been the subject of numerous studies. Current control strategies are mostly used by differential geometry, linear algebra, fuzzy regulators, and artificial neural networks. The objective of this study is to design an algorithm for autonomous control of the tractor-trailer system reversing based on an algorithm using a PSD controller and to verify it on a simulated mathematical model. All parameters listed in the models and experiments are performed based on the existing tractor-trailer system. Dynamic models of steering and velocity control were identified and incorporated into the simulation. Result includes a stable operation of the steering without oscillating. The proposed algorithm can be implemented in microcontrollers without the need for high computing power.

scholarly journals Research on an Asymmetric Fault Control Strategy for an AC/AC System Based on a Modular Multilevel Matrix Converter

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3137 ◽  
Author(s):  
Chong Zhang ◽  
Daozhuo Jiang ◽  
Xuan Zhang ◽  
Yiqiao Liang
Keyword(s):  
Control Strategy ◽  
Reference Frames ◽  
Control Strategies ◽  
Short Circuit ◽  
Matrix Converter ◽  
Current Control ◽  
Positive Sequence ◽  
Negative Sequence ◽  
Balancing Control ◽  
Secondary Side

This paper studies control strategies for an AC/AC system based on a modular multilevel matrix converter (M3C) when an asymmetric fault occurs in the secondary side ac system. Firstly, the operating principle of M3C is briefly introduced and verified by simulation. Then, based on its mathematical model by double αβ0 transformation, the decoupled control strategies for the primary side and secondary side systems are designed. In view of the asymmetric fault condition of the secondary side system, the positive sequence and negative sequence components of voltages and currents are separated and extracted, and then a proportional resonant controller (PR) is used to regulate the positive and negative sequence currents at the same time to realize decoupled current control in the αβ reference frames. The capacitor voltage balancing control, which consists of an inter-subconverter balancing control and an inner-subconverter balancing control, is realized by adjusting four circulating currents. Finally, the proposed control strategy is validated by simulation in the PSCAD/EMTDC software (Manitoba HVDC Research Center, Canada). The result shows that during the period of the BC-phase short-circuit fault occurring in the secondary side system, the whole system can still operate stably and transmit a certain amount of active power, according to their set values. Furthermore, the capacitor voltages are balanced, with a slight increase during the fault period. The simulation results verify the effectiveness of the proposed control strategy.

scholarly journals Performance Improvement of a Grid-Connected Inverter under Distorted Grid Voltage Using a Harmonic Extractor

Electronics ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1038
Author(s):  
Sungjoon Cho ◽  
Ho-Sung Kang ◽  
Kyo-Beum Lee ◽  
Ji-Yoon Yoo
Keyword(s):  
Control Strategy ◽  
High Harmonic ◽  
Harmonic Signal ◽  
Current Control ◽  
Grid Voltage ◽  
Current Controller ◽  
Synchronous Reference Frame ◽  
Distorted Grid ◽  
Harmonic Components ◽  
Grid Connected Inverter

This paper introduces an improved current control strategy for a grid-connected inverter system operating under distorted grid voltage conditions. Although existing current controllers for grid-connected inverters have proportional integral gains with suitable bandwidth, low-order harmonic components can be generated by distorted grid voltages. The proposed improved current controller is established in a synchronous reference frame that rotates at harmonic frequency. The input signals for the harmonic current controller should contain only the specific harmonic components requiring suppression. Therefore, the proposed current controller uses a harmonic extractor to distinguish current signals from fundamental and specific harmonic components. The harmonic extractor retains only the relevant harmonic components for individual current controllers with high harmonic signal ratios. This paper introduces two different strategies to extract specific harmonic components for the current controller. The proposed control strategy does not require any additional hardware filter circuits and can be implemented easily by designing a suitable digital filter. When using the proposed method, grid current quality is significantly improved compared to conventional methods that do not include harmonic extractors. The effectiveness of the proposed method is verified through simulations and practical experiments.

scholarly journals Phylogenetic Complexity of Morphologically Identified Anopheles squamosus in Southern Zambia

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 146
Author(s):  
Jordan Hoffman ◽  
Ilinca Ciubotariu ◽  
Limonty Simubali ◽  
Twig Mudenda ◽  
William Moss ◽  
...  
Keyword(s):  
Phylogenetic Relationships ◽  
Catchment Area ◽  
Control Strategies ◽  
Light Trap ◽  
Current Control ◽  
Control Measures ◽  
Morphological Identification ◽  
The Past ◽  
Blood Meal Source ◽  
Residual Malaria Transmission

Despite dramatic reductions in malaria cases in the catchment area of Macha Hospital, Choma District, Southern Province in Zambia, prevalence has remained near 1–2% by RDT for the past several years. To investigate residual malaria transmission in the area, this study focuses on the relative abundance, foraging behavior, and phylogenetic relationships of Anopheles squamosus specimens. In 2011, higher than expected rates of anthropophily were observed among “zoophilic” An. squamosus, a species that had sporadically been found to contain Plasmodium falciparum sporozoites. The importance of An. squamosus in the region was reaffirmed in 2016 when P. falciparum sporozoites were detected in numerous An. squamosus specimens. This study analyzed Centers for Disease Control (CDC) light trap collections of adult mosquitoes from two collection schemes: one performed as part of a reactive-test-and-treat program and the second performed along a geographical transect. Morphological identification, molecular verification of anopheline species, and blood meal source were determined on individual samples. Data from these collections supported earlier studies demonstrating An. squamosus to be primarily exophagic and zoophilic, allowing them to evade current control measures. The phylogenetic relationships generated from the specimens in this study illustrate the existence of well supported clade structure among An. squamosus specimens, which further emphasizes the importance of molecular identification of vectors. The primarily exophagic behavior of An. squamosus in these collections also highlights that indoor vector control strategies will not be sufficient for elimination of malaria in southern Zambia.

scholarly journals Mosquito Control Priorities in Florida—Survey Results from Florida Mosquito Control Districts

Pathogens ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 947
Author(s):  
Rishi Kondapaneni ◽  
Ashley N. Malcolm ◽  
Brian M. Vazquez ◽  
Eric Zeng ◽  
Tse-Yu Chen ◽  
...  
Keyword(s):  
State Government ◽  
Mosquito Control ◽  
Control Strategies ◽  
Mosquito Species ◽  
Research Priorities ◽  
Current Control ◽  
Control Programs ◽  
Common Control ◽  
Surveillance Programs ◽  
Research Questions

Florida lies within a subtropical region where the climate allows diverse mosquito species including invasive species to thrive year-round. As of 2021, there are currently 66 state-approved Florida Mosquito Control Districts, which are major stakeholders for Florida public universities engaged in mosquito research. Florida is one of the few states with extensive organized mosquito control programs. The Florida State Government and Florida Mosquito Control Districts have long histories of collaboration with research institutions. During fall 2020, we carried out a survey to collect baseline data on the current control priorities from Florida Mosquito Control Districts relating to (1) priority control species, (2) common adult and larval control methods, and (3) major research questions to address that will improve their control and surveillance programs. The survey data showed that a total of 17 distinct mosquito species were considered to be priority control targets, with many of these species being understudied. The most common control approaches included truck-mounted ultra-low-volume adulticiding and biopesticide-based larviciding. The districts held interest in diverse research questions, with many prioritizing studies on basic science questions to help develop evidence-based control strategies. Our data highlight the fact that mosquito control approaches and priorities differ greatly between districts and provide an important point of comparison for other regions investing in mosquito control, particularly those with similar ecological settings, and great diversity of potential mosquito vectors, such as in Florida. Our findings highlight a need for greater alignment of research priorities between mosquito control and mosquito research. In particular, we note a need to prioritize filling knowledge gaps relating to understudied mosquito species that have been implicated in arbovirus transmission.

Sign in / Sign up

Export Citation Format

Share Document