Renewable energy sources like wind, sun, and hydro are seen as a reliable alternative to the traditional energy sources such as oil, natural gas, or coal. Distributed power generation systems (DPGSs) based on renewable energy sources experience a large development worldwide, with Germany, Denmark, Japan, and USA as leaders in the development in this field. Due to the increasing number of DPGSs connected to the utility network, new and stricter standards in respect to power quality, safe running, and islanding protection are issued. As a consequence, the control of distributed generation systems should be improved to meet the requirements for grid interconnection. This paper gives an overview of the structures for the DPGS based on fuel cell, photovoltaic, and wind turbines. In addition, control structures of the grid-side converter are presented, and the possibility of compensation for low-order harmonics is also discussed. Moreover, control strategies when running on grid faults are treated. This paper ends up with an overview of synchronization methods and a discussion about their importance in the control

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Overview of Control and Grid Synchronization for Distributed Power Generation Systems

The use of distributed energy resources is increasingly being pursued as a supplement and an alternative to large conventional central power stations. The specification of a power-electronic interface is subject to requirements related not only to the renewable energy source itself but also to its effects on the power-system operation, especially where the intermittent energy source constitutes a significant part of the total system capacity. In this paper, new trends in power electronics for the integration of wind and photovoltaic (PV) power generators are presented. A review of the appropriate storage-system technology used for the integration of intermittent renewable energy sources is also introduced. Discussions about common and future trends in renewable energy systems based on reliability and maturity of each technology are presented

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Power-Electronic Systems for the Grid Integration of Renewable Energy Sources: A Survey

This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single-phase grid; 3) whether they utilizes a transformer (either line or high frequency) or not; and 4) the type of grid-connected power stage. Various inverter topologies are presented, compared, and evaluated against demands, lifetime, component ratings, and cost. Finally, some of the topologies are pointed out as the best candidates for either single PV module or multiple PV module applications.

A review of single-phase grid-connected inverters for photovoltaic modules

This book, written by two major figures in adaptive control, provides a wealth of material for researchers, practitioners, and students. While some researchers in adaptive control may note the absence of a particular topic, the book‘s scope represents a high-gain instrument. It can be used by designers of control systems to enhance their work through the information on many new theoretical developments, and can be used by mathematical control theory specialists to adapt their research to practical needs. The book is strongly recommended to anyone interested in adaptive control.

Adaptive Control

Solid-state switch-mode rectification converters have reached a matured level for improving power quality in terms of power-factor correction (PFC), reduced total harmonic distortion at input AC mains and precisely regulated DC output in buck, boost, buck-boost and multilevel modes with unidirectional and bidirectional power flow. This paper deals with a comprehensive review of improved power quality converters (IPQCs) configurations, control approaches, design features, selection of components, other related considerations, and their suitability and selection for specific applications. It is targeted to provide a wide spectrum on the status of IPQC technology to researchers, designers and application engineers working on switched-mode AC-DC converters. A classified list of more than 450 research publications on the state of art of IPQC is also given for a quick reference.

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A review of single-phase improved power quality AC-DC converters

A SiC-MOSFET composite boost converter for an electric vehicle power train application exhibits a volumetric power density of 22 kW/L and gravimetric power density of 20 kW/kg. The composite converter architecture, which is composed of partial-power boost, buck, and dual active bridge modules, leads to a 60% reduction in CAFE average losses, to a 280% improvement in power density, and to a 76% reduction in magnetics volume compared to the conventional Si-IGBT boost converter. These gains were achieved with the help of optimization based on a comprehensive loss model including SiC-MOSFET switching loss and magnetic losses based on the FEM method simulated in FEMM. Experimental results for the 22 kW/L SiC-MOSFET composite converter project 97.5% average efficiency on US06 driving cycle and a CAFE average efficiency of 97.8%.

SiC-MOSFET composite boost converter with 22 kW/L power density for electric vehicle application

This paper presents a simulation platform for the modeling and study of microgrid (MG) power systems. Using MathWorks Simulink modeling software, the platform provides a library of tools for designing and simulating the behavior of an MG on time scales from seconds to days. The library includes a collection of power system and power electronics components (sources, loads, switches, etc.) that may be arbitrarily configured. The platform also facilitates the study of energy management systems (EMS), which optimize the behavior of certain controllable sources and loads according to programmed algorithms. User-generated EMS routines can be integrated into an MG model.

A microgrid modeling and simulation platform for system evaluation on a range of time scales

This paper introduces a novel digital PFC (DPFC) control approach that requires no input voltage sensing or current loop compensation, yet results in low-harmonic operation over a universal input voltage range and loads ranging from high-power operation in continuous conduction mode down to near-zero load. The controller is based on low-resolution DPWM and A/D converters, requires no microcontroller or DSP programming, and is well suited for a simple, low-cost integrated-circuit realization, or as an HDL core suitable for integration with other power control functions. Experimental verification results are shown for a 500 W boost PFC rectifier.

A Digital PFC Controller without Input Voltage Sensing

This paper describes design and implementation of a 10 MHz digitally controlled buck converter realized in a standard 0.35um CMOS process. Based on a discrete-time power-stage model, we show that a 3rd-order compensator can be designed for improved transient responses and disturbance rejection compared to standard 2nd-order PID compensators. Efficient hardware realization includes a look-up table type compensator, a 10-bit hybrid DPWM (2-bit counter, 5-bit delay-line, and 3-bit dither) and a power stage optimized for efficiency

Digitally controlled 10 MHz monolithic buck converter

A digital controller configured to inject a signal into a digital feedback path that facilitates regulation of a power converter and measure the corresponding phase, gain, or frequency. The digital controller may also include an adaptive tuning controller for adjusting power converter operating attributes based in part on the measurements. In an exemplary embodiment, the adaptive tuning controller uses the phase, gain, and/or frequency measurements to adjust the digital feedback signal. In an exemplary embodiment, the adaptive tuning controller compares the operating measurements with desired values and generates adjusted operating attributes. In accordance with an exemplary embodiment, the monitoring and adjusting of the digital feedback signal occurs while the digital controller is regulating a power signal in the power converter.

Dragan Maksimovic

Papers

SiC-MOSFET composite boost converter with 22 kW/L power density for electric vehicle application

A microgrid modeling and simulation platform for system evaluation on a range of time scales

A Digital PFC Controller without Input Voltage Sensing

Digitally controlled 10 MHz monolithic buck converter

Monitoring and control of power converters