Analysis and Implementation of a Single-Phase Bridgeless Hybrid Switched-Capacitor Rectifier in Discontinuous Conduction Mode for Power Factor Correction-

 

Analysis and Implementation of a Single-Phase Bridgeless Hybrid Switched-Capacitor Rectifier in Discontinuous Conduction Mode for Power Factor Correction

 Chrystian Mumic 1,∗, Marcus V. Soares 2, Yales R. de Novaes 1, Alan J. Watson 3 1Santa Catarina State University, Dept of Electrical Engineering, Joinville, Brazil. 2Silicon Austria Labs, Division Power Electronics, Graz, Austria. 3University of Nottingham, Dept. Electrical and Electronic Engineering, Nottingham, United Kingdom.

ABSTRACT 

This work presents the quantitative and qualitative analysis, as well as the experimental results of a practical implementation of the Single-Phase Bridgeless Hybrid Switched Capacitor Rectifier operating in discontinuous conduction mode (DCM) to achieve a high input power factor. Operating in DCM provides several advantages, including natural power factor correction (PFC) behavior of the input current and reduced semiconductor switching losses. The paper begins with a literature review on key studies of hybrid switched-capacitor converters with a high power factor. Subsequently, the converter analysis, including its modulation scheme, operational stages and design methodology, is detailed. The proposed approach is validated with results from a practical prototype implementation, achieving an output voltage of 1200 V and an output power of 315 W from an input voltage of 220 V. The converter demonstrated an efficiency of 97.3%, a power factor of 0.99, and harmonic distortion levels within the limits specified by IEC61000-3-2.

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https://www.scielo.br/j/epot/a/5y7jTFXzM53WrZB7W5zKdWP/?format=pdf&lang=en

UAPFs topologies with UPS features for low and medium voltage applications-Welflen Ricardo Nogueira Santos1 , Eisenhawer de Moura Fernandes2, Edison Roberto Cabral da Silva2, Marcus Andre Barros Nogueira Carneiro1, Antonio Airton Carneiro de Freitas1, Patryckson Marinho Santos3

 

UAPFs topologies with UPS features for low and medium voltage applications 

 Welflen Ricardo Nogueira Santos1 , Eisenhawer de Moura Fernandes2, Edison Roberto Cabral da Silva2, Marcus Andre Barros Nogueira Carneiro1, Antonio Airton Carneiro de Freitas1, Patryckson Marinho Santos3 1Electrical Engineering Department, Federal University of Piauí, Campus Universitário Ministro Petrônio Portella, s/n Bairro Ininga, 64049-550, Teresina – PI, Brazil 2Mechanical Engineering Department, Federal University of Campina Grande, R. Aprígio Veloso, 882 – Universitário, 58429-900, Campina Grande – PB, Brazil 3Electrical Engineering Department, Federal University of Maranhão, Av. dos Portugueses, 1966 – Vila Bacanga, 65080-805, São Luís – MA, Brazil

 Abstract: Some configurations of universal active power filter (UAPF) with uninterruptible power supplies (UPSs) features for single-phase applications are proposed in this study focus on a reduced number of power electronic switches. All proposed configurations, composed by two-leg converters, compensate for current and voltage harmonics and provide power factor control close to one. Comparisons between the structures are made in terms of converters voltage capabilities, shared-leg, and capacitor currents. The model of the systems, including the equations and control system, is detailed described. Steady-state analysis of the proposed configurations demonstrates the existence of a load angle, which reduces the converters current, increasing the efficiency of the proposed systems. A complete set of simulated and experimental results are presented. 

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https://www.academia.edu/27448011/A_Novel_AC_UPS_With_High_Power_Factor_and_Fast_Dynamic_Response?email_work_card=view-paper 

YAKOVLEV,Streklov, El'stin, Khaikin - Problems in Undergraduate Physics Volume II Electricity and Magnetism

 

This set of four books of problems is based on a translation of a Russian collection which has been in use by students in physics at Moscow State University and the Moscow Physico-Technical In­stitute for a number of years. Where appropriate, answers and solutions to the problems are given in the second part of each volume.

VIEW BOOK : https://archive.org/details/problems-in-undergraduate-physics-volume-ii-electricity-and-magnetism

Stability Enhancement of Inverter-dominated power systems with virtual inertia control by Lalitha Subramanian -THÈSE Pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ GRENOBLE ALPES Spécialité : GENIE ELECTRIQUE

Stability Enhancement of Inverter-dominated power systems with virtual inertia control Lalitha Subramanian THÈSE Pour obtenir le grade de DOCTEUR DE L’UNIVERSITÉ GRENOBLE ALPES Spécialité : GENIE ELECTRIQUE 

 SUMMARY

 The electric power system has been traditionally energized by synchronous machines like steam turbines, hydro turbines, and diesel engines. These rotating machines inherently contribute to the system resilience by providing rotational inertia. The presence of an adequate inertia in the system provides the liberty of allowing a control delay for the governor-input valve controls to respond to the frequency deviation. With the displacement of synchronous machines by converter-connected sources, the reduction of inherent system inertia is evident. However, there is also a counterpoised observation that the required amount of inertia in the transformed power system is reduced, given the faster response of the converter-based DERs. Therefore, we resort to synthetic inertia to improve the resilience of a low-inertia grid. In this context, this thesis explores questions such as: What is the adequate synthetic inertia/frequency response capability for a stable power system? How can we quantify the flexibility required to provide this adequate inertia? Does inertia greater than the adequate level necessarily indicate a higher stability margin? How different is the effect of distributed synthetic inertia on the oscillatory stability compared to synchronous inertia? Firstly, the aspects of flexibility and methods to characterize them for an adequate synthetic inertia and fast-frequency response are addressed. A generalized virtual storage flexibility model has been proposed to quantify the heterogeneous bidirectional flexibilities and their combination to provide a certain level of synthetic inertia. As an illustration, a hybrid energy storage system has been sized to provide synthetic inertia and fast-frequency response for a standard power network.The subsequent chapters discuss synthetic inertia and fast-frequency control actuated by PV systems with hybrid energy storage. In this thesis, inverter control has been explored with a complete DC-side model takes into account the effects of PV intermittency, unlike most research works on inverter control that assumes a sufficiently large DC source/sink. Synthetic inertia controllers are categorized as grid-following and grid-forming topologies, which significantly affect their impact on system stability. Conventionally, the inertia and damping parameters are tuned and fixed over a scheduled time slot based on the available flexibility. It has been identified that a higher inertia is required on the occurrence of a disturbance to limit the rate of frequency deviation and a higher damping is required for a faster settling time. Therefore, for each of the control topologies, a rule-based real-time inertia tuner has been proposed to optimize the frequency deviation, its rate, and the settling time. The algorithm has been improved through a model predictive control with a rate-based linearization. The rate-based linearization extends the model validity to the transient zones.For systems with multiple grid-formers and multiple frequency responsive units, a distributed optimization problem has been formulated and solved to collectively tune the inertia and damping parameters which are constrained by the available flexibilities.The efficacy of distributed grid-forming and grid-following synthetic inertia in replacing their synchronous counterpart in a microgrid has been compared. Microgrid regulation in grid-connected and islanded modes have been studied by modeling the DERs with discussed control strategies. The impact of the two types of synthetic inertia controls on the small signal stability of the system are examined by modal analysis and bifurcation plots to derive the conditions for oscillatory stability in a microgrid with distributed synthetic inertia reserves. The effectiveness of the proposed control strategies in restoring the frequency stability of low-inertia systems has been validated by power hardware-in-the-loop experimentation.

VIEW FULL THESIS: https://theses.hal.science/tel-03505925v1/document

Multilevel Multiplexed Inverters for Applications up to 1500 Volts and 100 kW. by Kepa Odriozola Sagasta

Multilevel Multiplexed Inverters for Applications up to 1500 Volts and 100 kW. by Kepa Odriozola Sagasta

SUMMARY

 Renewable energy, including solar and wind, is at the heart of the transition to a less carbon intensive and more sustainable energy system. Over the past two decades, there has been a significant increase in photovoltaic (PV) power installed in new solar power plants. This increase in power has also led to an increase in DC bus voltage up to 1500V (the limit between LV and MV in DC). It is worth noting that grid integration of distributed energy sources such as PV systems with battery based energy storage systems (BESS), both utility-scale and residential and industrial, is gaining importance. At the same time, the global data sphere is projected to grow from 33 zettabytes (ZB, 1021 bytes, one trillion gigabytes) in 2018 to 175 ZB in 2025. Due to the data tsunami, digitization, high-speed wireless networks, new data-intensive technologies, and the growing demand for cloud-computing have led to the development of data centers, which have become an electricity intensive industry. For example, several studies have estimated that between 2025 and 2050, the ICT industry could account for up to 20% of global electricity consumption. The increase in installed power of data centers and solar power plants implies high power converters (MW or more) connected in parallel. The increase in voltage for PV and energy storage is a strong challenge to reduce the level of current in the devices in order to obtain more compact systems, because today, with the current solutions, the objectives of efficiency, cost and power density are not met. Therefore, new high-efficiency power electronic systems and associated control strategies are needed to make this transition possible. This thesis is part of the study and design of a new family of high efficiency three phase multilevel converter topologies, called Multiplexed, intended for UPS, Energy Storage and Solar Inverter applications. The case studied, foresees a converter with a high voltage DC bus with a voltage variation range from 900VDC to 1500VDC, connected to a grid or a three-phase load of American (480VAC/60Hz) or European (400VAC/50Hz) voltage, and a bidirectional power ranging from a few tens of kW to 100kW. First, we will explain the general structure of multiplexed topologies. Basically, the structure is composed of a chopper stage (consisting of two symmetrical DC-DC converters) connected to a three phase DC-AC inverter stage. There are many variants depending on the topologies chosen for each conversion stage. In a second part, we will present the selected variants as a solution to the studied applications. We will also specify, the approach adopted for the dimensioning of these solutions, by considering the active elements (semiconductors) and the passive elements. We will present the performance results obtained via simulation. We will specify the control principle associated with this new range of topologies. Indeed,one of the main features of these structures is that the two stages, chopper and inverter, are connected without intermediate filter which implies that the inverter must re-switch the voltage that has already been switched by the chopper stage. The PWM modulation strategy that has been developed for this purpose will then be presented and detailed. Finally, based on the models and results obtained in the previous sections, we will show the realization of the 100kW prototypes built in order to validate the architecture and the control strategy proposed around the 'Multiplexed' concept.

VIEW FULL THESIS: https://theses.hal.science/tel-04222473v1/document