- 标题
- 摘要
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- 实验方案
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Enhanced Active Power balancing capability of Grid connected Solar PV fed Cascaded H-bridge Converter
摘要： Cascaded H-bridge converter is a promising solution for next generation large scale PV system having both active and reactive power exchange capacity. However, one challenge with this converter is unbalanced power generation among the clusters or cells due to variation in radiation level, temperature, dusting on PV cells etc. In order to inject balanced power to the grid, in this paper, a controlled exchange of reactive power is proposed so that the converter can work with unbalanced power generation within the clusters. Magnitude of reactive power exchange is derived and necessary conditions discussed. Additionally, the magnitude of zero voltage is derived taking into account both active and reactive power exchange with the grid. By exchanging reactive power, the converter can also be used during low voltage ride through (LVRT) condition. This paper introduces a novel representation of unbalanced power generation using barycentric coordinate system which helps to identify regions in the power plane which require the exchange of reactive power. The proposed method is verified through computer simulation and in a laboratory prototype.
关键词： Maximum Power point tracking (MPPT),Active power,Zero sequence voltage,Reactive power,Solar Photovoltaic,Cascaded H-bridge multilevel converter(CHB)
更新于2025-09-23 15:23:52
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A Hybrid MMC-Based Photovoltaic and Battery Energy Storage System
摘要： This paper proposes a new configuration and its control strategy for a modular multilevel converter (MMC)-based photovoltaic (PV)-battery energy storage (BES) system. In the MMC-based PV-BES system, each PV submodule is interfaced from its dc side with multiple PV generators using isolated dual active bridge (DAB) dc-dc converters. One BES system is embedded into each arm of the converter and is connected to the dc port of the associated BES submodule using multiple isolated DAB converters. The embedded BES systems are used to smooth the output power of the PV generators and limit the rate of change of the power delivered to the host grid. Moreover, they enable compensation of power mismatches between the arms and legs of the system by exchanging power with the arms of the converter. The paper then proposes a hybrid power mismatch elimination strategy using a combination of power exchange with the arms of the converter and internal power flow control of the MMC. The proposed hybrid power mismatch elimination strategy employs BES systems and differential currents to compensate power mismatches and transfer power between the arms and legs of the converter, respectively. The effectiveness of the proposed power smoothing technique using the embedded BES systems and hybrid power mismatch elimination strategy is demonstrated using time-domain simulations conducted on a switched model of the PV-BES system in PSCAD/EMTDC software environment.
关键词： control,modular multilevel converter,power electronics,battery energy storage,photovoltaic,power mismatch,Differential current,energy conversion,integration
更新于2025-09-23 15:22:29
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A novel photovoltaic battery energy storage system based on modular multilevel converter
摘要： Modular multilevel converters (MMCs) have been widely applied in photovoltaic battery energy storage systems (PV-BESSs). In this paper, a novel topology of PV-BESS based on MMC is proposed, where the batteries are connected to the sub-modules through DC-DC converters. It is necessary to analyze the control strategies of both DC-DC converters and MMC. Specifically, the capacitor voltage balancing and the modulation mode are important. The sorting method is proposed to balance the capacitor voltages in this paper. Moreover, carrier phase shift-square wave modulation with the highest voltage utilization ratio and the highest power transfer capability is proposed to generate PWM singles for MMC-PV-BESS. In order to verify the availability of the proposed control strategy, a simulation model is built and related experiments are carried out. The simulation results and experimental results are consistent with the theory. As a result, the voltages of all capacitors could be balanced, and the MMC-PV-BESS could reliably work.
关键词： photovoltaic,modular multilevel converter,battery energy storage system,DC-DC converter,control strategy
更新于2025-09-23 15:21:21
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[IEEE 2018 11th UK-Europe-China Workshop on Millimeter Waves and Terahertz Technologies (UCMMT) - HangZhou, China (2018.9.5-2018.9.7)] 2018 11th UK-Europe-China Workshop on Millimeter Waves and Terahertz Technologies (UCMMT) - Linear-to-Circular Polarization Conversion For Beam-Scanning Antenna Based On Self-Complementary Metasurface
摘要： Modular multilevel converters (MMC) are presently the converter topology of choice for voltage-source converter high-voltage direct-current (VSC-HVDC) transmission schemes due to their very high efficiency. These converters are complex, yet fast and detailed electromagnetic transients simulation models are necessary for the research and development of these transmission schemes. Excellent work has been done in this area, though little objective comparison of the models proposed has yet been undertaken. This paper compares for the first time, the three leading techniques for producing detailed MMC VSC-HVDC models in terms of their accuracy and simulation speed for several typical simulation cases. In addition, an improved model is proposed which further improves the computational efficiency of one method. This paper concludes by presenting evidence-based recommendations for which detailed models are most suitable for which particular studies.
关键词： HVDC transmission,electromagnetic-transient (EMT) simulation,voltage-source converter (VSC),modular multilevel converter (MMC),Accelerated model
更新于2025-09-23 15:19:57
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[IEEE 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Guangzhou, China (2019.5.19-2019.5.22)] 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Waveguide Switchable Bandstop and Bandpass Filters Using RF MEMS Switches
摘要： Modular multilevel converter (MMC) topology is discussed intensively as a crucial part of future dc grids, especially to integrate offshore wind power. While generalized voltage-source converter models are usually utilized for multiterminal investigations, conclusions on transient dc grid behavior and on ac–dc interactions during distorted ac grid conditions are hard to draw or are limited in their signi?cance. In this paper, a MMC-based dc grid framework with a tripartite focus on an internal converter as well as dc and ac grid control is presented. Besides, an evaluation of the implemented MMC model that incorporates the available arm sum voltage, a decoupled ac and dc current system control concept that is suitable to handle unbalanced voltage conditions is derived for HVDC applications. Combined with wind farm arrays, this collocation allows a meaningful examination of hybrid ACDC structures and the implemented dc grid control methodologies. To provide proof of the universal applicability of this framework, simulations are carried out on a ?ve-terminal system.
关键词： MMC energy balancing,unbalanced operation,wind power integration,HVDC grid control,Generalized modular multilevel converter (MMC) modeling,power converter
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Cu-doping Effects in CdSe <sub/>x</sub> Te <sub/>1-x</sub> /CdTe Solar Cells
摘要： Modular multilevel converter (MMC) topology is discussed intensively as a crucial part of future dc grids, especially to integrate offshore wind power. While generalized voltage-source converter models are usually utilized for multiterminal investigations, conclusions on transient dc grid behavior and on ac–dc interactions during distorted ac grid conditions are hard to draw or are limited in their signi?cance. In this paper, a MMC-based dc grid framework with a tripartite focus on an internal converter as well as dc and ac grid control is presented. Besides, an evaluation of the implemented MMC model that incorporates the available arm sum voltage, a decoupled ac and dc current system control concept that is suitable to handle unbalanced voltage conditions is derived for HVDC applications. Combined with wind farm arrays, this collocation allows a meaningful examination of hybrid ACDC structures and the implemented dc grid control methodologies. To provide proof of the universal applicability of this framework, simulations are carried out on a ?ve-terminal system.
关键词： MMC energy balancing,unbalanced operation,wind power integration,HVDC grid control,Generalized modular multilevel converter (MMC) modeling,power converter
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE Industry Applications Society Annual Meeting - Baltimore, MD, USA (2019.9.29-2019.10.3)] 2019 IEEE Industry Applications Society Annual Meeting - Elimination of Phase Unbalance in Cascaded Multilevel Converters for Large-Scale Photovoltaic Grid Integration
摘要： Cascaded H-bridge converters (CHB) are ideal candidates for large-scale photovoltaic (PV) power plants because of their modular structure and the absence of bulky line frequency power transformer. To eliminate leakage current, isolated dc-dc converters are needed to connect the PV arrays to the H-bridges of CHB. These dc-dc converters extract maximum power from each PV array independently. Under partial shading conditions, the power generated in the three phases of CHB is different, leading to an unbalance in the grid currents. The existing methods to balance the grid currents require the converter to be overrated or operate at reduced PV power. So a new topology is proposed to distribute the power equally among the three phases of CHB without overrating the converter or reducing the PV power. This is achieved by using high-frequency transformers each having one primary and three secondaries. Simulation results are presented to validate the proposed topology.
关键词： grid integration,multilevel converter,phase unbalance,photovoltaic applications,Cascaded H-bridge (CHB) converter
更新于2025-09-16 10:30:52
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[IEEE 2019 3rd International conference on Electronics, Communication and Aerospace Technology (ICECA) - Coimbatore, India (2019.6.12-2019.6.14)] 2019 3rd International conference on Electronics, Communication and Aerospace Technology (ICECA) - Reliability Modeling and Evaluation of Five-Level Converter Integrated with Photovoltaic System
摘要： Recent renewable energy system is heavily dependent upon power electronic devices like multilevel converter (MLC), for integrating renewable energy sources to the grid or to provide power to loads in islanding mode. However, the power electronic switches used in these converters have high failure rates (approximately 34%). Therefore reliability study of these converters is of paramount importance. Most of the research has been done to develop an efficient, cost-effective, fault-tolerant topology and to reduce the number of device count, but reliability study of these topologies has not been explored much. In this paper, comparison of some of the existing five-level topologies has been made on the basis of device count, peak device current, number of dc voltage sources and capacitors required to produce the same peak output voltage. The best among these topologies are selected for reliability modeling and evaluation. The failure rate of different elements of this topology is computed (i) by assuming junction temperature same for all the devices (ii) by deriving junction temperature from the measured power loss of the elements with the help of simulation using PSIM version 9.0 thermal block. Each element exhibits different failure as these elements have different power loss across them. The reliability from both the approach is computed and compared and found that the total failure rate of converter computed from power losses of switches is 2.5% higher and accurate than the failure rate computed from the second one.
关键词： MTTF,multilevel converter,RBD,reliability,failure rate,five-level converter
更新于2025-09-16 10:30:52
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An Alcohol-Soluble Polymer Electron Transport Layer Based on Perylene Diimide Derivatives for Polymer Solar Cells
摘要： Modular multilevel converter with integrated battery energy storage system (MMC-BESS) has been proposed for energy storage requirements in high-voltage applications with large-scale renewable energy resources. The MMC-BESS is essentially a three-port converter which can transfer energy between any two of the ac port, dc port, and BESS, constituting multimode operation of the system. Different from conventional MMCs, the state-of-charge (SOC) inconsistency among batteries would magnify the submodule capacitor voltage unbalance issue in the MMC-BESS. In this study, an improved capacitor voltage balancing method applicable for multimode operation of MMC-BESS is proposed by adjusting ac and dc modulation indexes simultaneously. After that, the ratio of ac and dc modulation indexes is optimised to enhance the tolerance of unbalanced power among SMs within phase arm, greatly improving the SOC equalisation rate. Based on the proposed capacitor voltage balancing method, the control structure is given and the dynamic model is conducted for the analytic design of the closed-loop controller. Finally, the simulations and experimental results validate the effectiveness and feasibility of the proposed control strategy.
关键词： SOC equalisation,Multimode operation,Modular multilevel converter,Battery energy storage system,Capacitor voltage balancing
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Novel Voltage Balancing Techniques for Modular Multilevel PV Inverters
摘要： Modular multilevel converters (MMC) are widely used in medium and high voltage transmission systems and in STATCOM applications for improving the power quality. In this paper, a modified configuration of MMC is considered to integrate a MW PV plant with the high voltage grid more likely at the transmission side of the power system. A string of PV panels is connected across each of the submodules (SMs) of the modular multilevel PV inverter (MMPI). In addition, two novel voltage-balancing techniques have been proposed to regulate the SM capacitor voltages of the MMPI at different maximum power point voltages. The first technique utilizes the concept of capacitor sorting based on their voltages. The proposed algorithm generates the switching states based on the voltages of the other SM capacitors and hence reduces the ripple in the capacitor voltage. In the second technique, a novel and simplified logic function based voltage balancing technique is developed. This technique is computationally efficient, reduces the ripple in capacitor voltage, eliminates the requirement of a look-up table and can be easily extended to an N-level MMPI. A three-level and seven-level MMPI is simulated in MATLAB/SIMULINK. The simulated MMPI is tested under two scenarios for different temperature and irradiance conditions and various waveforms are showcased to ensure the efficacy of the proposed techniques.
关键词： Modular multilevel PV inverter (MMPI),Logic function,Maximum power point tracking (MPPT),Modular multilevel converter (MMC),Voltage balancing
更新于2025-09-04 15:30:14