PV inverters for module level applications

Dissertação para obtenção do Grau de Mestre em Energias Renováveis – Conversão Eléctrica e Utilização SustentáveisNowadays, the photovoltaic (PV) energy is presented as one of the most promising source of clean energy, and so a good way for greenhouse gas emissions mitigation and reduce the fossil fuel dependence. Within it, the photovoltaic energy has caused a huge interest in the electronic converters, and the need to improve their efficiency and reducing their cost. With this work I present a solution for a module scale grid-connected single-phase inverter. The solution consists in a two-stage inverter insolated with a grid line transformer. The two-stage inverter is composed by a DC-DC converter and a DC-AC converter connected through a DC-link capacitor. The DC-DC converter in case is a boost converter used to elevate the voltage from the PV module to a higher level. For the DC-AC converter it is used a full-bridge inverter, and both the DC-DC and the DC-AC converters use the IGBTs form an integrated module with its respective drivers. To the boost control it is implemented a Maximum Power Point Tracking algorithm that can optimize the power extraction from the PV source and for the inverter it is used a sliding mode hysteretic control. Once this inverter is conceived to work connected to the grid, a single-phase PLL system is used to synchronize the injected current to grid voltage. All the control part is made digitally using an Arduino Uno board, which uses an Atmel microcontroller

Microwave system performance summary

The design of the microwave system for the solar power satellite is described. Design modifications recommended include changes in phase control to the power module level, a reduction in allowable amplitude jitter, the use of metal matrix waveguides, and sequences for startup/shutdown procedures. Investigations into reshaping the beam pattern to improve overall rectenna collection efficiency and improve sidelobe control are surveyed

Determining an Optimal Display Module-Level White Point Target for a Display Module

This publication describes techniques for determining an optimal display module‑level white point target for a display module considering a device‑level white point calibration brightness drop. In aspects, a distribution of display modules includes a distribution of module‑level white points that are centered around a module‑level white point target. A computing device manufacturer fits a two‑dimensional Gaussian function to the distribution and calculates an average brightness drop for the distribution once calibrated to a device‑level white point target. Using the Gaussian function, the manufacturer recalculates the average brightness drop for a shifted distribution. The manufacturer repeats this process until an optimal module‑level white point target that includes a minimum average brightness drop is determined. The manufacturer includes a new distribution of display modules centered around the optimal module‑level white point target in computing devices that have a display. Thus, after device‑level white point calibration, the average brightness drop in the computing devices is minimized

Module-level power converters for parallel connected photovoltaic arrays

A new solar technology with the capability to increase array-level power production is introduced by using simple integrated power converters that connect directly to photovoltaic (PV) panels is investigated. The power converters proposed here are full-bridge DC-DC converters with high voltage gain that operate with an open-loop control scheme. The outputs of these converters could then be directly connected to a grid-tie converter eliminating the need to connect panels in series to achieve the appropriate voltage. With a high-efficiency converter, the total system efficiency would increase even though one panel in the array may be compromised. The simulation results show that a highly-efficient converter is possible. To assist in experimentation, an auxilary [sic] circuit using a microcontroller was implemented to supply power and gate signals to the gate driver of the power converters. The design and construction of a transformer for use with the full-bridge converter is discussed. A novel transformer topology is utilized to increase converter efficiency. The converters were tested both in a laboratory environment and outdoors for solar data collection. Transient response, source regulation and load regulation analysis was performed. The maximum power points of the array were investigated for different insolation levels. Even when insolation differs substantially, the panel output power levels are within their individual maximum power levels when the total output is maximized even without independent power trackers. Analysis of both field data and random insolation indicate that the new approach does increase power generation and therefore system efficiency --Abstract, page iii

Biological interaction networks are conserved at the module level

<p>Abstract</p> <p>Background</p> <p>Orthologous genes are highly conserved between closely related species and biological systems often utilize the same genes across different organisms. However, while sequence similarity often implies functional similarity, interaction data is not well conserved even for proteins with high sequence similarity. Several recent studies comparing high throughput data including expression, protein-protein, protein-DNA, and genetic interactions between close species show conservation at a much lower rate than expected.</p> <p>Results</p> <p>In this work we collected comprehensive high-throughput interaction datasets for four model organisms (<it>S. cerevisiae, S. pombe, C. elegans</it>, and <it>D. melanogaster</it>) and carried out systematic analyses in order to explain the apparent lower conservation of interaction data when compared to the conservation of sequence data. We first showed that several previously proposed hypotheses only provide a limited explanation for such lower conservation rates. We combined all interaction evidences into an integrated network for each species and identified functional modules from these integrated networks. We then demonstrate that interactions that are part of functional modules are conserved at much higher rates than previous reports in the literature, while interactions that connect between distinct functional modules are conserved at lower rates.</p> <p>Conclusions</p> <p>We show that conservation is maintained between species, but mainly at the module level. Our results indicate that interactions within modules are much more likely to be conserved than interactions between proteins in different modules. This provides a network based explanation to the observed conservation rates that can also help explain why so many biological processes are well conserved despite the lower levels of conservation for the interactions of proteins participating in these processes.</p> <p>Accompanying website: <url>http://www.sb.cs.cmu.edu/CrossSP</url></p

Module-Level Modelling Approach for a Cloudbased Digital Twin Platform for Li-Ion Batteries

The pursue of the new increasingly intelligent, and heavier state estimation algorithms requires a significant amount of data and computing power, which may challenge their deployment in current BMS solutions. To address that issue, this paper proposes a cloud-based Digital Twin Platform to extend computing power and data storage capacity. This tool aims to contain the integration of models to analyse thermoelectricand ageing aspects of a LIB, based on experimental operation data by comparative analysis. Based on well-known cell-level modelling techniques, a module-level modelling approach is proposed and an experimental validation platform is suggested

Design of module level converters in photovoltaic power systems

The application of distributed maximum power point tracking (DMPPT) technology in solar photovoltaic (PV) systems is a hot topic in industry and academia. In the PV industry, grid integrated power systems are mainstream. The main objective for PV system design is to increase energy conversion efficiency and decrease the levelized cost of electricity of PV generators. This thesis firstly presents an extensive review of state-of-the-art PV technologies. With focus on grid integrated PV systems research, various aspects covered include PV materials, conventional full power processing DMPPT architectures, main MPPT techniques, and traditional partial power processing DMPPT architectures. The main restrictions to applying traditional DMPPT architectures in large power systems are discussed. A parallel connected partial power processing DMPPT architecture is proposed aiming to overcome existing restrictions. With flexible ‘plug-and-play’ functionality, the proposed architecture can be readily expanded to supply a downstream inverter stage or dc network. By adopting smaller module integrated converters, the proposed approach provides a possible efficiency improvement and cost reduction. The requirements for possible converter candidates and control strategies are analysed. One representative circuit scheme is presented as an example to verify the feasibility of the design. An electromagnetic transient model is built for different power scale PV systems to verify the DMPPT feasibility of the evaluated architecture in a large-scale PV power system. Voltage boosting ability is widely needed for converters in DMPPT applications. Impedance source converters (ISCs) are the main converter types with step-up ability. However, these converters have a general problem of low order distortion when applied in dc-ac applications. To solve this problem, a generic plug-in repetitive control strategy for a four-switch three-phase ISC type inverter configuration is developed. Simulation and experimental results confirm that this control strategy is suitable for many ISC converters.The application of distributed maximum power point tracking (DMPPT) technology in solar photovoltaic (PV) systems is a hot topic in industry and academia. In the PV industry, grid integrated power systems are mainstream. The main objective for PV system design is to increase energy conversion efficiency and decrease the levelized cost of electricity of PV generators. This thesis firstly presents an extensive review of state-of-the-art PV technologies. With focus on grid integrated PV systems research, various aspects covered include PV materials, conventional full power processing DMPPT architectures, main MPPT techniques, and traditional partial power processing DMPPT architectures. The main restrictions to applying traditional DMPPT architectures in large power systems are discussed. A parallel connected partial power processing DMPPT architecture is proposed aiming to overcome existing restrictions. With flexible ‘plug-and-play’ functionality, the proposed architecture can be readily expanded to supply a downstream inverter stage or dc network. By adopting smaller module integrated converters, the proposed approach provides a possible efficiency improvement and cost reduction. The requirements for possible converter candidates and control strategies are analysed. One representative circuit scheme is presented as an example to verify the feasibility of the design. An electromagnetic transient model is built for different power scale PV systems to verify the DMPPT feasibility of the evaluated architecture in a large-scale PV power system. Voltage boosting ability is widely needed for converters in DMPPT applications. Impedance source converters (ISCs) are the main converter types with step-up ability. However, these converters have a general problem of low order distortion when applied in dc-ac applications. To solve this problem, a generic plug-in repetitive control strategy for a four-switch three-phase ISC type inverter configuration is developed. Simulation and experimental results confirm that this control strategy is suitable for many ISC converters

Anticipating Full Vehicle Radiated EMI from Module-Level Testing in Automobiles

EMI due to common-mode currents on cables routed in automobiles was studied using a test device designed to mimic a vehicle. Both experimental work and Finite-Difference Time-Domain (FDTD) modeling were employed in this paper. The good agreement between the measurements and modeling results indicates that the numerical tools can be a useful aid in predicting vehicle-level EMI by developing vehicle transfer functions and measuring the module-level EMI characteristics on the bench top

Modular Multilevel Converters with Module-Level Energy Storage for Medium Voltage Applications

This dissertation is on Modular Multilevel Converter (MMC) converter design and analysis and its integration with energy storage at the low voltage module-level. The developed converter concept and topology can be used in various applications especially for the support of intermittent renewable energy resources. The general converter structure is analyzed and extended to include integrated energy storage suitable but not limited to medium voltage applications. The behavior of the idealized structure is analyzed to obtain equations that govern general converter behavior and identify possible control loops. Detail mathematical switching model is developed for the MMC converter with generalized module structure. The switching model is averaged to obtain a large signal model and then reduced to obtain lower order models suitable for sizing and optimization. Open and compensated closed loop current control is proposed and extended to include feedback loops needed for full control of integrated energy storage. General sizing procedure with the optimization aspects is then proposed and used on the example system to obtain the converter structure parameters. The example system models are then used to fine tune the control and structure parameters and investigate the converter behavior