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 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...

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,...

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....

This work presents the construction of a model for PV panel using single-diode five-parameters model, based exclusively on data-sheet parameters. The takes into account series and parallel (shunt) resistance panel. equivalent circuit basic equations cell/panel in Standard Test Conditions (STC) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> are shown, as well parameters extraction from values. temperature dependence cell dark saturation...

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...

There is a strong trend in the photovoltaic inverter technology to use transformerless topologies order acquire higher efficiencies combining with very low ground leakage current. In this paper, new topology, based on H-bridge ac bypass circuit consisting of diode rectifier and switch clamping dc midpoint, proposed. The topology simulated experimentally validated, comparison other existing performed. High conversion efficiency current are demonstrated.

This paper presents a detailed analysis of the two most well-known hill-climbing maximum power point tracking (MPPT) algorithms: perturb-and-observe (P&O) and incremental conductance (INC). The purpose is to clarify some common misconceptions in literature regarding these trackers, therefore helping selection process for suitable MPPT both researchers industry. methods are thoroughly analyzed from mathematical practical implementation view. Their reveals that there no difference between two....

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...

Voltage source inverters connected to the grid in applications such as active rectifiers, filters, uninterruptible power supplies, and distributed generation systems need an optimal ac current control. To obtain zero steady-state error at fundamental frequency (i.e., unity factor), use of a standard integrator rotating frame is effective resonant controller stationary frame. However, voltage harmonics influence generate unless several integrators multiple frames or compensators are adopted....

Power-electronics-based microgrids (MGs) consist of a number voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis parallel-connected three-phase VSIs are derived. The proposed current inner loops mathematical models based on stationary reference frame. A hierarchical scheme for paralleled VSI system is developed comprising two levels. primary includes droop method virtual impedance loops, order to share active reactive...

Grid synchronization algorithms are of great importance in the control grid-connected power converters, as fast and accurate detection grid voltage parameters is crucial order to implement stable strategies under generic conditions. This paper presents a new method for three-phase three-wire networks, namely dual second-order generalized integrator (SOGI) frequency-locked loop. The based on two adaptive filters, implemented by using SOGI stationary αβ reference frame, it able perform an...

This paper proposes a novel control for voltage-source inverters with the capability to flexibly operate in grid-connected and islanded modes. The scheme is based on droop method, which uses some estimated grid parameters such as voltage frequency magnitude angle of impedance. Hence, inverter able inject independently active reactive power grid. controller provides proper dynamics decoupled from grid-impedance phase. system also flows large range impedance values. Simulation experimental...

Power processing systems will be a key factor of future photovoltaic (PV) applications. They play central role in transferring, to the load and/or grid, electric power produced by high-efficiency PV cells next generation. In order come up expectations related use solar energy for producing electrical energy, such must ensure high efficiency, modularity, and, particularly, reliability. The goal this paper is provide an overview open problems and focus attention researchers industries on...

The main objective of this study is to increase the penetration level photovoltaic (PV) power production in low-voltage (LV) grids by means solar inverters with reactive control capability. This paper underlines weak points standard strategies which are already imposed certain grid codes, and then, introduces a new method that based on sensitivity analysis. analysis shows same amount becomes more effective for voltage support if inverter located at end feeder. Based fundamental knowledge,...

A decentralized power control method in a single-phase flexible ac microgrid is proposed this paper. Droop widely considered to be good choice for managing the flows between converters manner. In work, enhance loop dynamics, droop combined with derivative controller used islanded mode. grid-connected mode, strictly factor point of common coupling (PCC), an integral adopted. Small-signal analysis shown both and The scheme does not need any mode switching action. Thus, it relatively simple...

This paper presents the development and test of a flexible control strategy for an 11-kW wind turbine with back-to-back power converter capable working in both stand-alone grid-connection mode. The is featured complex output voltage controller handling nonlinear load excess or deficit generated power. Grid-connection mode current also enabled case isolated local grid involving other dispersed generators such as turbines diesel generators. A novel automatic switch method based on phase-locked...

This paper analyzes and compares three transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on safety issues that result from lack of galvanic isolation. A common-mode model, valid at frequencies lower than 50 kHz, is adopted to study leakage current paths. The model validated by both simulation experimental results. These will be used compare selected topologies, explain influence system unbalance neutral conductor inductance current. It...

This paper presents a high-performance maximum power point tracker (MPPT) optimized for fast cloudy conditions, e.g., rapidly changing irradiation on the photovoltaic panels. The conditions are tracked by an hill-climbing MPPT method called dP-P&O. algorithm separates effects of change from effect tracker's perturbation and uses this information to optimize tracking according change. knowledge direction enables use different schemes cases increasing, decreasing, or steady irradiance. When...

This paper proposes a new technique for grid synchronization under unbalanced and distorted conditions, i.e., the dual second order generalised integrator - frequency-locked loop (DSOGI-FLL). system results from application of instantaneous symmetrical components method on stationary orthogonal alphabeta reference frame. The generalized concept (SOGI) is exploited to generate in-quadrature signals used frequency-adaptive characteristic achieved by simple control loop, without using either...

The PI current control of a single-phase inverter has well known drawbacks: steady-state magnitude and phase error limited disturbance rejection capability. When the controlled is connected to grid, results in power factor decrement capability leads need grid feed-forward compensation. However imperfect compensation action high harmonic distortion consequently noncompliance with international standards. In this paper new strategy aimed mitigate these problems proposed. Stationary-frame...