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Phase-locked loops (PLLs) are very important in power and energy areas. Many PLLs have been proposed in recent literatures, and all these methods are to design a robust filter and let them be as a preprocessing tool before the synchronous reference frame PLL (SRF-PLL) input. Among these PLLs, a interesting PLL is Least-Error Squares (LES) Filter-Based PLL (LES-PLL), which is composed of a LES filter...
Cascaded or distributed module-level inverters are becoming increasingly desirable for photovoltaic applications. The authors have demonstrated an AC-stacked topology that allows each inverter to operate completely autonomously from all the others. The only required communications is a low-bandwidth synchronization signal communicated from the point-of-grid-connection. This paper describes the communications...
For a grid-connected Voltage-Source Converter (VSC), dynamics of the grid synchronization plays an important role in affecting the converter performances and stability. Due to its significance, this paper gives a comparative analysis about some basic grid synchronization schemes, through viewpoint of dynamic performances, which appeared as the impacts of voltage perturbation on the estimated angle...
Phase-locked loops (PLLs) are doubtless the most popular synchronization technique in the power converters. Almost all proposed PLL structures known in literature are inherently nonlinear and can be linearized as second order linear time invariant system. Nonlinear nature of PLLs degrades their performances, and question arises if there exist an enhanced PLL structure that would have superior performances...
This paper proposes Fault Detection, Isolation and Reconfiguration (FDIR) techniques to realize the connection of a DFIM pumped storage system with the grid in the presence of current and speed sensor failures. For the detection method authors use the parity space approach either for current sensor failure or the rotation speed one. The proposed reconfiguration techniques exploit stator flux estimation...
The deterioration of power quality is posing an increasing problem for low and medium voltage grids. At the same time, grid codes place ever stricter requirements for the operation of distributed generation systems, especially regarding fault-ride-through capabilities during more severe grid fault events. Therefore, a proper operation of converter-based power systems needs to be guaranteed, requiring...
The growing number of renewable energy sources and power electronic participants are increasingly endangering the quality of supply at distribution grid level. A modular shunt-connected power conditioning system featuring uninterruptible power supply capability is proposed to locally increase power quality and supply reliability. This paper proposes an operation-mode-adaptive cascaded control strategy...
Unpredictable power quality (PQ) events such as, balanced and unbalanced voltage sag/swell, frequency shift, phase jump and harmonic distortions in the utility grid voltage drastically affects the performance of a grid interfaced distributed generation (DG) systems due to unreliable synchronization. This paper presents adaptive synchronization based dq-current control technique for three-level NPC...
This paper develops a grid voltage sensor-less control strategy of Voltage Source Inverter (VSI) used for photovoltaic application. Virtual-Flux (VF) estimator is investigated to estimate the three-phase grid voltages. A second order generalized integrator-quadrature signal generation SOGI-QSG and Frequency Loocked Loop FLL is achieved to ensure the grid synchronisation and to estimate the grid voltages...
Cascaded Multi-level inverter for synchronization of power generated from PV system to utility grid is reported in this paper. Inverters are prone to several types of faults e.g. switch failure or dc link capacitor failure. Failure mode analysis of cascaded H-Bridge is widely discussed in the literature. Various methods for post-fault operation with reduced capacity (due to module failure) but with...
In this paper, Active and Reactive power management with the utility grid is achieved by integrating 7-level quasi Impedance Source Inverter (qZSI) with Thyristor based elements (Thyristor Switched Capacitor (TSC) and Thyristor Switched Reactor (TSR)). Major portion of the reactive power is managed by the thyristor based elements and the remaining reactive power is managed by the cascaded qZSI. The...
An advanced Solar Photovoltaic plant controllers designed to improve system performance, reduce the need for ancillary services, and provide ancillary services instead of or in competition with conventional resources. This paper presents control model of three phase grid connected photovoltaic generation system with new approach for reactive power regulation. In order to maximize the power output,...
With the fast development in Photovoltaic (PV) technology, the relevant grid-connection requirements/standards are continuously being updated, and more challenges have been imposed on both single-phase and three-phase grid-connected PV systems. For instance, PV systems are currently required to remain connected under grid voltage sags (even zero voltage condition). In this case, much attention should...
This paper presents design and performance of high power quality single-phase grid inverter that fed from photovoltaic (PV) system through maximum power tracker for residential application. The proposed designed inverter is based on sinusoidal pulse width modulation (SPWM) technique in combination with series-resonance and high-pass filters at low side of inverter. The filters and SPWM are designed...
Wind energy conversion systems are widely considered as the emerging solutions for green technology in the field of generation because of their user and eco-friendly interface. The research deals with modelling, simulation and regulation of a grid integrated wind systems using doubly fed induction generator. Major concern in grid connected power systems is regarding the power quality measurements...
The operation of grid side converters (GSC) is significant in its robust control design. Phase locked loop (PLL) algorithm is introduced to acquire synchronization and perfect operation of GSC. The control design depends on rapid and exact tracking of phase angle of grid voltage. The task of PLL is crucial condition, since grid connected system is to operate the power system under grid fault conditions...
The grid synchronization system, which plays an important role in the control of grid-connected power converters, often needs to manipulate the grid voltage to extract the fundamental and harmonic sequence components. Generally a prefilter can achieve this function. In this paper, a systematic and general approach to design the multiple block based prefilter is introduced. First a complex variable...
Micro hydro power plants (MHPPs) based microgrids (MG) which usually use squirrel cage induction generators have been studied in the past decade, but the majority of the control solutions are for autonomous operation. Thus, more studies should be dedicated to the grid connection of such particular microgrids. The present paper tackles this aspect by proposing a simple control structure that can provide...
Due to the increasing popularity of renewable energies, a significant share of the power generation in future microgrids is expected to originate from converter-interfaced Distributed Energy Resources (DERs). Traditionally, idealized device models are used to conduct grid stability studies. For instance, a DER interfaced via a Voltage-Source Converter (VSC) would be modeled as an ideal current or...
Performance of grid-connected converter relies on fast and precise estimation of phase angle and amplitude of the fundamental component of grid voltage signal to guarantee the proper synchronization of DG in modern power systems. However, the extent to which the frequency is estimated is dependent on the type of grid voltage abnormalities and structure of the phase-locked loop or frequency locked...
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