1,721,002 research outputs found
Self-Consumption Optimization in an Energy Community
No full textIn recent years, a fast penetration of renewable sources in power electrical systems is taking place, providing many benefits; indeed, thanks to the Energy Community development, there is the possibility that renewable energy generated by a user can be shared by the other users of the community too. However, to make this happen, power electronics converters are the main characters of a proper management of shared energy. In this paper authors propose a Simulink scheme of an Energy Community, in which converters and related control systems have been modelled. Through the Maximum Power Point Tracking control of the photovoltaic converter, the maximum photovoltaic power is extracted, and through the double-loop control of the grid-connected inverter, only active power is fed into the grid, generating a current in phase with the grid voltage. The major innovation introduced in this paper is the modelling of a power sharing supervisor system that coordinates all the bidirectional converters which interface batteries to the community, according to their states of charge, in order to set power exchanges with the grid to zero. Results obtained from simulations demonstrate that, by varying load, photovoltaic production and batteries states of charge, the self-consumption optimization aim is pursued
DSCC Converter as Energy Router for Rural Energy Communities: a Case Study Under Vertical Imbalance
No full textThe sustainable electrification of rural communities relies on the effective utilization and integration of renewable energy sources, which are generally connected to the grid using multiple independent converters. In contrast, the adoption of a single centralized multiport converter acting as energy router can help to reduce operation costs, to increase power density, and to simplify energy management and maintenance, offering a more efficient solution compared to multiple converters. This paper investigates the use of modular multilevel converters acting as a multiport energy router to connect various energy sources to the grid. In this scenario, a vertical imbalance in the arm voltages of the converter, due to the different operation patterns of the connected sources, can harm the stability of the converter. The system's internal dynamics can be leveraged as a control mechanism to ensure system functionality and to prevent unequal stress on semiconductor devices within the individual cells. A case study involving vertical imbalance is analyzed in this paper to assess the converter's potential to improve the reliability and efficiency of renewable energy integration in rural electrification projects
Improving Rural Microgrid Performance with SiC MOSFET-Based Three-Phase Inverters
No full textMicrogrids represent a fundamental solution for the electrification of rural communities, providing clean energy through renewable resources. This article explores the importance of integrating SiC MOSFET based three-phase inverters. These new generation transistors are known for their good electrical and thermal characteristics, guaranteeing significant advantages in terms of energy efficiency, thermal management, and operational reliability, making them ideal for high-power and high-frequency applications. The research focuses on the design, analysis, and future modeling of a three-phase inverter, whose results demonstrate an improvement in its performance with a significant reduction in losses compared to those that would occur with the use of a traditional silicon transistor. Furthermore, a suggestion is made on the possible construction of a thermal model, which would allow the simulation of the inverter for the optimization of the entire microgrid. The results highlight how the use of SiC MOSFETs can improve the performance of microgrids, supporting the electrification of rural areas with sustainable energy solutions
A Single-Cell-Based Injection Method for Circulating Current Control in MMC
No full textModular multilevel converters are becoming more and more attractive for many high-voltage high-power applications. However, due to their topology and operation they present technical challenges in the implementation of the control system, such as balancing of the submodule capacitor voltages and suppressing the circulating currents. The circulating current introduces additional power losses, increases the current stress on power devices and reduces their lifetime. The aim of this paper is to propose an innovative control technique for the elimination of the circulating current by injecting a low-frequency alternating signal into a single submodule of each converter arm, to also achieve a reduction of the voltage ripple across capacitor, beneficial to extend their lifetime. Experimental results performed on a seven-levels converter are presented to validate the proposed technique and assess its performance in comparison with state-of-the-art approaches
An Innovative Single-Cell-Based Injection Method to Improve Efficiency and Reliability of MMC with Low Implementation Burden
No full textModular multilevel converters are increasingly gaining popularity in various high-voltage and high-power applications. However, their operation poses some technical challenges in implementing the control system, including issues, such as balancing submodule capacitor voltages and mitigating circulating currents. The presence of circulating currents leads to additional power losses, increases thermal stress on the power devices, and shortens their lifetime. This article introduces an innovative control technique to eliminate circulating currents by injecting a low-frequency alternating signal into a single submodule of each converter arm. The proposed method not only addresses circulating current mitigation but is also able to reduce capacitor voltage ripple and peak arm current, thereby enhancing the overall converter's lifespan and efficiency. Results of experimental tests on a seven-level converter are presented to prove the effectiveness of the proposed technique and compare its performance with existing state-of-the-art approaches
Control of H-bridge based multilevel converters
No full textMultilevel converters are suitable for high voltage and high power applications. Among them H-bridge ones have encountered good success due to their simpler layout and the reduced number of components over the counterparts. H-bridge multilevel converters used as active rectifiers represent an attractive solution in traction systems due to the possibility to reduce the ac filter size and to boost the dc voltage. Moreover they can feed many dc loads at the price of considerable difficulties in ensuring stability of the overall system. The Passivity Based Theory seems suitable to address and solve such a kind of problem. The main idea is to design a non-linear controller which function is to shape systems energy aiming to obtain the desired behavior. A comparison is made between a control technique using classical PI controllers and a Passivity based control
A Method for the Parameter Identification of an AC Motor High-Frequency Model Based on the Exchange Market Algorithm
No full textThe use of wide bandgap semiconductor devices, such as SiC and GaN MOSFETs, in high-frequency converters introduces new challenges for the design of electric drives. The very fast switching transient of which these devices are capable, in fact, can become a serious threat for the reliability of the entire system. Electromagnetic interferences due to the high dv/dt and di/dt, voltage reflections along the cable that cause overvoltage and ringing at the motor terminals, and large common-mode voltages that produce current circulation in the motor bearings are recognized as the major phenomena leading to premature failure of the drive. It is therefore important for designers to approach the problem from a system point of view, having the possibility to accurately model the system in the high frequency domain to take appropriate measures to increase reliability. In this paper, an automated fitting procedure is proposed to identify one of the most accurate high-frequency models of an induction machine. The procedure relies on the experimental measurement of the differential, common-mode and parasitic impedance of the tested machine and adopts Exchange Market optimization algorithm to search for the best approximation of the three measured impedances. Implementation issues and advantages are presented and discussed
Design of H-bridge multilevel active rectifier for traction systems
No full textThis paper focuses on the design of a controller for a high-voltage high-power single-phase active rectifier, designed for, but not limited to, traction field applications. The rectifier should absorb current with low harmonic content to reduce the environmental electromagnetic pollution and to eliminate the disturbances to the on-board communication equipment. In addition, it should allow the elimination of the heavy and bulky transformer, reducing encumbrance and cost. A multilevel H-bridge single-phase configuration has been chosen and the design has been fully investigated with the help of theoretical analysis, simulations, and experiments
Design of a Multilevel Front-End Stage for Traction System with the Passivity Theory
No full textThis work addresses the control of a high voltage, high power single phase rectifier suitable for traction applications. A multilevel H-bridge single phase configuration has been considered. Such a converter often presents instability problems making difficult its design and uncertain its behaviour. This paper proposes a new controller based on the passivity-based approach. Such a controller allows stability, unity-power factor, good balancing of the two DC links and a satisfactory transient behaviour even in presence of sudden load changes. A different choice of the damping parameters allows fulfilling the system requirements in terms of reduced DC link voltage error or low grid current distortion or to find an optimum trade-off between them. The better performance in comparison with a PI are demonstrated
An energy-based control for an n-H-bridges multilevel active rectifier
No full textThis paper deals with the control of a multilevel n-H-bridges front-end rectifier. This topology allows n distinct dc buses to be fed by the same ac source offering a high loading flexibility suitable for traction applications as well as for industrial automation plants. However, this flexibility can lead the system to instability if the dc buses operate at different voltage levels and with unbalanced loads. Thus, linear controllers, designed on the basis of the small-signal linearization, are not effective any longer and stability can not be ensured as large-signal disturbances occur. The use of a passivity-based control (PBC) designed via energy considerations and without small-signal linearization properly fits stability problems related to this type of converter. The system has been split into n subsystems via energy considerations in order to achieve the separate control of each dc bus and its stability in case of load changes or disturbances generated by other buses. Then, a set of n passivity-based controllers (one for each subsystem) is adopted: the controllers are linked using dynamical parameters computed through energy balance equations. Hence, the system dc buses are independent and stable as experimental results demonstrate
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