Solid-state switch mode AC-DC converters having high-frequency transformer isolation are developed in buck, boost, and buck-boost configurations with improved power quality in terms of reduced total ...harmonic distortion (THD) of input current, power-factor correction (PFC) at AC mains and precisely regulated and isolated DC output voltage feeding to loads from few Watts to several kW. This paper presents a comprehensive study on state of art of power factor corrected single-phase AC-DC converters configurations, control strategies, selection of components and design considerations, performance evaluation, power quality considerations, selection criteria and potential applications, latest trends, and future developments. Simulation results as well as comparative performance are presented and discussed for most of the proposed topologies.
In this paper, different voltage injection schemes for dynamic voltage restorers (DVRs) are analyzed with particular focus on a new method used to minimize the rating of the voltage source converter ...(VSC) used in DVR. A new control technique is proposed to control the capacitor-supported DVR. The control of a DVR is demonstrated with a reduced-rating VSC. The reference load voltage is estimated using the unit vectors. The synchronous reference frame theory is used for the conversion of voltages from rotating vectors to the stationary frame. The compensation of the voltage sag, swell, and harmonics is demonstrated using a reduced-rating DVR.
Summary
This article proposes an adaptive and modified Perturb and Observe (P&O) maximum power point tracking (MPPT) algorithm, using fuzzy logic step size controller, for a wind energy conversion ...system (WECS) based on wound rotor synchronous generator. The modified P&O controller uses additional current information of the dc‐link, to decrease power oscillation around MPP, and choose the correct direction of the perturbation, while wind speed increase condition, depending on the sign of dc‐link current change. So, in this contribution, a modified drift‐free P&O algorithm was chosen because it gives better results, but the duty cycle step size in the proposed MPPT controller has been varied adaptively, using a fuzzy logic inference system based on the variation of the rectifier output power and the previous change of the duty cycle to get fast convergence until the MPP is reached in increasing and decreasing wind speed conditions. Performances and robustness of the proposed speed sensorless MPPT controller are evaluated in an experiment implementation, using a WECS emulator and dSpace DS1104 controller board, where experimental results show that the proposed method guarantees fast convergence with better energy quality and high robustness against speed or load change conditions.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This paper presents a power factor correction (PFC)-based bridgeless Luo (BL-Luo) converter-fed brushless dc (BLDC) motor drive. A single voltage sensor is used for the speed control of the BLDC ...motor and PFC at ac mains. The voltage follower control is used for a BL-Luo converter operating in discontinuous inductor current mode. The speed of the BLDC motor is controlled by an approach of variable dc-link voltage, which allows a low-frequency switching of the voltage source inverter for the electronic commutation of the BLDC motor, thus offering reduced switching losses. The proposed BLDC motor drive is designed to operate over a wide range of speed control with an improved power quality at ac mains. The power quality indices thus obtained are under the recommended limits of IEC 61000-3-2. The performance of the proposed drive is validated with test results obtained on a developed prototype of the drive.
In this paper, a new active power control (APC) with enhanced maximum power point tracking (MPPT) algorithm are implemented to improve the performances of a solar photovoltaic system (SPV) based ...standalone water pumping station. The APC uses proportional resonant controller with antiwindup (AWPRC) for ac voltage regulation without saturation phenomena and with high power quality at the point of common coupling. Furthermore, the proportional resonant controller design method for optimal gains to achieve high performance during transition period in terms of phase margin and desired settling time is analyzed. To achieve the MPPT with less oscillation while protecting the battery energy storage system from overvoltage, an enhanced power ratio variable step based perturbation and observation algorithm is used. The effectiveness of the developed control strategies are validated through simulations and experimental results.
The reliability of conventional photovoltaic (PV) structure in shaded situations can undergo different issues related to internal and external conditions. The internal condition accounts for the ...inhomogeneity of the properties of electrothermal cells, while the external conditions connote optimal power maximum tracking techniques and protection circuit limitations. This article proposes a new technique to improve the reliability of shaded panels, considering the internal and the external issues. Our study begins with an extensive analysis to assess the vulnerability of PV cells to second-quadrant thermal stress and operational limits of bypass diode protection against hot spot. Consequently, we proposed a new system that concurrently operates with the maximum power extraction process to assist bypass diodes with hot-spot protection. This proposition results in a reconfigured panel with both a local detection circuit that defines the conduction states of bypass diodes and additional mosfet s that switch shaded subgroups. In this article, an algorithm was developed that is capable of controlling the optimal maximum operation point tracking with an on-demand deployment of the protection mosfet s, using the signals provided by the local detection circuit. A set of experiments were carried out in order to demonstrate the capability of the proposed method to prevent hot-spot damages over all shading rates and operating points. The novelty of the proposed approach is its low cost of implementation as well as its simple and efficient design. Therefore, it has the potential to be easily integrated along side existing infrastructure and maximum power point tracking algorithms.
In this paper, hardware-in-the-loop (HIL) implementation of solar photovoltaic (PV) array feeding autonomous load, without dump load, is investigated. Two control algorithms based on the sliding mode ...approach are designed to guarantee a fast and finite-time convergence without adjustment of the system parameters. The dc-dc boost converter and the current controlled-voltage source converter (CC-VSC) are controlled to maximize the power from the PV, to protect the battery energy storage system (BESS) from overcharging, and to regulate the voltage and frequency at the point of common coupling (PCC). An accurate stability analysis of the system is presented and discussed in this work. The effectiveness and the robustness of the developed controllers are validated by simulation and experimental results during the load perturbation and varying climate conditions.
In this paper, a distribution static compensator (DSTATCOM) is implemented for controlling a distributed power generating system using a proposed composite observer based control technique. The ...proposed control technique is employed for the fundamental components extraction of distorted load currents. These extracted components are used in the estimation of reference source currents to generate gating signals of DSTATCOM. The proposed control technique is implemented for the mitigation of reactive power, distortion in term of harmonics, and load balancing under linear/nonlinear loads. The performance of DSTATCOM is observed satisfactory for these consumer loads with regulated generator voltage at point of common coupling and self-supported dc link of voltage-source converter of DSTATCOM.
This paper presents a two stage three-phase grid-interfaced solar photovoltaic (SPV) energy conversion system with an adaptive notch filter (ANF)-based control algorithm. The proposed SPV system is a ...multifunction grid-interfaced SPV energy conversion system, which along with the conversion of dc-power from SPV to ac mains is capable of reactive power compensation, harmonics currents elimination, and load balancing in a three-phase ac distribution system. Compared with multiple devices with different functionalities, a multifunction grid-interfaced SPV energy conversion system is capable of saving substantially capital investment, space, and maintenance cost on behalf of multifunctional features. The ANF successfully extracts a single sinusoid of a possibly nonstationary nature from harmonics corrupted load currents at point of common coupling. The control algorithm is adaptive with respect to the fundamental frequency of the system as compared with other methods, and provides instantaneous values of the fundamental signals. Simulation and experimental results verify the validity of the presented algorithm and confirms its desirable transient and steady state performances. The total harmonics distortion of grid currents is found well under IEEE-519 standard, even under nonlinear loads.
This paper presents a novel structure for a three-phase four-wire (3P4W) distribution system utilizing unified power quality conditioner (UPQC). The 3P4W system is realized from a three-phase ...three-wire system where the neutral of series transformer used in series part UPQC is considered as the fourth wire for the 3P4W system. A new control strategy to balance the unbalanced load currents is also presented in this paper. The neutral current that may flow toward transformer neutral point is compensated by using a four-leg voltage source inverter topology for shunt part. Thus, the series transformer neutral will be at virtual zero potential during all operating conditions. The simulation results based on MATLAB/Simulink are presented to show the effectiveness of the proposed UPQC-based 3P4W distribution system.
