Renewable energy sources like wind, sun, and hydro are seen as a reliable alternative to the traditional such oil, natural gas, or coal. Distributed power generation systems (DPGSs) based on renewable experience large development worldwide, with Germany, Denmark, Japan, USA leaders in this field. Due increasing number of DPGSs connected utility network, new stricter standards respect quality, safe running, islanding protection issued. As consequence, control distributed should be improved...

The enabling of ac microgrids in distribution networks allows delivering distributed power and providing grid support services during regular operation the grid, as well powering isolated islands case faults contingencies, thus increasing performance reliability electrical system. high penetration generators, linked to through highly controllable processors based on electronics, together with incorporation energy storage systems, communication technologies, loads, opens new horizons...

The global electrical energy consumption is rising and there a steady increase of the demand on power capacity, efficient production, distribution utilization energy. traditional systems are changing globally, large number dispersed generation (DG) units, including both renewable nonrenewable sources such as wind turbines, photovoltaic (PV) generators, fuel cells, small hydro, wave gas/steam powered combined heat stations, being integrated into at level. Power electronics, technology...

This paper proposes a step-by-step procedure for designing the LCL filter of front-end three-phase active rectifier. The primary goal is to reduce switching frequency ripple at reasonable cost, while same time achieving high-performance rectifier (as characterized by rapid dynamic response and good stability margin). An example design reported has been built tested using values obtained from this design. experimental results demonstrate performance both controller. system stable grid current...

The recently introduced proportional-resonant (PR) controllers and filters, their suitability for current/voltage control of grid-connected converters, are described. Using the PR controllers, converter reference tracking performance can be enhanced previously known shortcomings associated with conventional PI alleviated. These include steady-state errors in single-phase systems need synchronous d–q transformation three-phase systems. Based on similar theory, filters also used generating...

DC-link capacitors are an important part in the majority of power electronic converters which contribute to cost, size and failure rate on a considerable scale. From capacitor users' viewpoint, this paper presents review improvement reliability dc link from two aspects: 1) reliability-oriented dc-link design solutions; 2) conditioning monitoring during operation. Failure mechanisms, modes lifetime models suitable for applications also discussed as basis understand physics-of-failure. This...

Phase, amplitude and frequency of the utility voltage are critical information for operation grid-connected inverter systems. In such applications, an accurate fast detection phase angle, amplotude is essential to assure correct generation reference signals cope with new upcoming standards. This paper presents a phase-locked-loop (PLL) method single-phase The novelty consists in generating orthogonal system using structure based on second order generalized integrator (SOGI). proposed has...

The aim of this paper is to analyze the stability problems grid connected inverters used in distributed generation. Complex controllers (e.g., multiple rotating dq-frames or resonant-based) are often required compensate low frequency voltage background distortion and an LCL-filter usually adopted for high one. possible wide range impedance values (distributed generation suited remote areas with radial distribution plants) challenge effectiveness LCL-filter-based current controlled system. It...

This paper presents a new multiresonant frequency-adaptive synchronization method for grid-connected power converters that allows estimating not only the positive- and negative-sequence components of signal at fundamental frequency but also other sequence harmonic frequencies. The proposed system is called MSOGI-FLL since it based on both decoupling network consisting multiple second-order generalized integrators (MSOGIs) frequency-locked loop (FLL), which makes adaptive. In this paper,...

The large-scale integration of power electronic based systems poses new challenges to the stability and quality modern grids. wide timescale frequency-coupling dynamics converters tend bring in harmonic instability form resonances or abnormal harmonics a frequency range. This paper provides systematic analysis future power-electronic-based systems. basic concept phenomena are elaborated first. It is pointed out that breed small-signal problems, featuring waveform distortions at frequencies...

This paper discusses the evaluation of different current controllers employed for grid-connected distributed power generation systems having variable input power, such as wind turbines and photovoltaic systems. The focus is mainly set on linear proportional-integral, proportional-resonant, deadbeat (DB) controllers. Additionally, an improved DB controller robust against grid impedance variation also presented. Since implementation these applications, their made in three operating conditions....

The steady growth of installed wind power together with the upscaling single turbine capability has pushed research and development converters toward full-scale conversion, lowered cost pr kW, increased density, also need for higher reliability. In this paper, converter technologies are reviewed focus on existing ones those that have potential but which not been yet adopted due to important risk associated high-power industry. classified into single- multicell topologies, in latter case...

Wind power is still the most promising renewable energy in year of 2013. The wind turbine system (WTS) started with a few tens kilowatt 1980s. Now, multimegawatt turbines are widely installed even up to 6-8 MW. There widespread use distribution networks and more stations, acting as plants, connected directly transmission networks. As grid penetration level increase steadily, starts have significant impacts system. Therefore, advanced generators, electronic systems, control solutions be...

A new era of power electronics was created with the invention thyristor in 1957. Since then, evolution modern has witnessed its full potential and is quickly expanding applications generation, transmission, distribution, end-user consumption electrical power. The performance electronic systems, especially terms efficiency density, been continuously improved by intensive research advancements circuit topologies, control schemes, semiconductors, passive components, digital signal processors,...

This paper deals with a fundamental aspect in the control of grid-connected power converters, i.e., detection positive-sequence component at frequency utility voltage under unbalanced and distorted conditions. Accurate fast this grid faults is essential to keep over exchange avoiding trip converter protections allowing ride-through transient fault. In paper, systematic use well known techniques conducts new system which exhibits fast, precise, frequency-adaptive response faulty Three...

This paper proposes a unified impedance model of grid-connected voltage-source converters for analyzing dynamic influences the phase-locked loop (PLL) and current control. The mathematical relations between models in different domains are first explicitly revealed by means complex transfer functions space vectors. A stationary (αβ-) frame is then proposed, which not only predicts stability impact PLL, but also reveals its frequency coupling effect. Furthermore, shaping effects PLL on control...

This paper addresses the harmonic stability caused by interactions among wideband control of power converters and passive components in an ac power-electronics-based system. The impedance-based analytical approach is employed expanded to a meshed balanced three-phase network which dominated multiple current- voltage-controlled inverters with LCL- LC-filters. A method deriving impedance ratios for different proposed means nodal admittance matrix. Thus, contribution each inverter system can be...

The increasing penetration of distributed power generation into the system leads to a continuous evolution grid interconnection requirements. In particular, active control will play an important role both during faults (low-voltage ride-through capability and controlled current injection) in normal conditions (reserve function frequency regulation). aim this paper is propose flexible based on fast controller reconfigurable reference selector. Several strategies select are studied compared...

This paper investigates on power-sharing issues of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the microgrid studied here comprises dc and ac subgrids interconnected by power electronic interfaces. The main challenge is to manage flows among all sources distributed throughout two types subgrids, certainly tougher than previous efforts developed for only or wider scope control has not yet been investigated, would rely coordinated operation sources,...