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This study presents a new scheme of control for the synchronization of a photovoltaic (PV) system with a three-phase grid without a line sensor. The approach of the proposed synchronization technique is developed to extract the maximum of PV energy and inject it in the network for various conditions of voltage, and to ensure that the currents injected into the three-phase network emulate the wished sinusoidal forms even when the mains grid voltage is no longer ideal. This paper introduces a new technique of synchronization and elimination of the disturbances created by the distorted tension based on the direct power control without voltage sensors (VF_DPC) with the help of second-order generalized integrator (SOGI) associated with a self-tuning filter (STF) to extract the fundamental virtual flux. The simulation of the proposed system is realized in MATLAB/Simulink environment.

This paper has presented improved control structure based direct power control (DPC) applied for shunt active power filtering. Basically, DPC control strategy employs instantaneous active and reactive power terms as controlled variables. This work introduces an integration concept of predictive control algorithm for shunt active power filter system application. Process of this latter adopts discrete model of PWM converter in the aim to predict future behaviour of the system. Switching vector selection principles for predictive control is very different compared to conventional method. For conventional DPC the selection is performed via heuristic switching table while predictive DPC algorithm takes on an optimized way based on cost function minimization depending to power errors, this latter evaluate the effects of each active voltage vector and the one reducing the cost function is chosen to be applied in the next sampling period. The application of optimal switching state leads to regulate the input active and reactive power which resulted in the cancellation of harmonic power component contained in the network. Simulation results are presented to verify the validity and effectiveness of the proposed predictive DPC in terms of dynamic and steady state performance for shunt active power filtering application.

In this paper, a new virtual flux (VF) based predictive direct power control (VF_PDPC) applied for three-phase pulse width modulation (PWM) rectifier is proposed. The virtual flux estimation is performed using a pure integrator in series with a new adaptive algorithm in order to cancel dc offset and harmonic distortions in the estimated VF. The introduced structure is able to produce two virtual flux positive sequence components orthogonal output signals under unbalanced and distorted voltage conditions. The main features of the proposed virtual flux estimator are, it's simple structure, accuracy, and fast VF estimation over the excited integrators. Therefore, the estimated VF is then used for robust sensorless VF-PDPC with a constant switching frequency using space vector modulation (SVM) and tested through numerical simulations. The instantaneous active and reactive powers provided by orthogonal (VF) positive sequence components are directly controlled. More importantly, this configuration gives quasi-sinusoidal and balanced current under different input voltage conditions without using the power compensation methods. The results of the simulation confirmed the validity of the proposed virtual flux algorithm and demonstrated excellent performance under different input voltage conditions, complete rejection of disturbances.

This study presents a new scheme of control for the synchronization of a photovoltaic (PV) system with a three-phase grid without a line sensor. The approach of the proposed synchronization technique is developed to extract themaximum of PV energy and inject it in the network for various conditions of voltage, and to ensure that the currents injected into the three-phase network emulate the wished sinusoidal forms even when the mains grid voltage is no longer ideal. This paper in troduces a new technique of synchronization and elimination of the disturbances created by the distorted tension based on the direct power control without voltage sensors (VF_DPC) with the help of second-order generalized integrator (SOGI) associated with a self-tuning filter(STF) to extract the fundamental virtual flux. The simulation of the proposed system is realized in MATLAB/Simulink environment.

This paper proposes basic concepts of a fixed speed wind turbine (FSWT), as an introduction to a modern wind turbine concept; also, energy extraction from the wind turbine, in order to highlight the utility of the Direct Torque Control (DTC) and Hysteresis Current Control (HCC) in the field of the quality of the electric power. The HCC will be applied to the grid side converter on the way to control the DC link voltage [1]. The Induction Generator (IG) wind turbine connected to the network using back-to-back PWM converters (AC/DC/AC). The theoretical principle of this method is discussed. From the simulation results, it is shown that DTC and HCC display several features, such as a simple algorithm and good dynamic response [2].

The extensive use of non-linear loads in industry becomes increasingly a serious problem that affects the quality of energy delivered to customers. Therefore, the shunt active power filter (SAPF) has emerged as an important industrial tool to eliminate induced harmonic currents and compensating of reactive power. This paper proposes an improved control configuration for SAPF based on a modern technique called predictive direct power control (Predictive-DPC). The principle of this control is based on the direct regulation of the instantaneous active and reactive powers to guarantee a good energy quality on the grid side. For this purpose the appropriate average voltage vector which cancels power tracking errors is calculated by a simple predictive model at the bigining of each control period. This type of control includes various features such as the lack of look up table (LUTs) and closed current loops and the constant switching frequency is achieved through the use of PWM modulation. The results of the simulation process show a high performance in the steady and transient state function for predictive-DPC control that might be a reasonable alternative to conventional DPC in the field of active power filtering.

This paper proposes a sensorless direct power regulation based sliding mode control of a wind energy system. The aim of this paper is to evaluate the performance of the system control and tracking accuracy of rotor position estimator. Sliding mode approach introduces a direct calculation of rotor side and grid side converter voltages by the control law developed. A model-reference adaptive system (MRAS) is used to estimate the rotor position. Simulation results for the system are provided to demonstrate the effectiveness and robustness of the used control.

This paper presents a Direct Power Control (DPC) for the Rotor Side Converter (RSC) of Doubly-Fed Induction Generator (DFIG) connected to the wind energy conversion system, as an alternative to the classical vector control (FOC). In this work a simple but effective DPC is proposed to achieve quick response and acceptable steady state performance at reason of using a conventional switching table to select the appropriate voltage vectors to the Rotor Side Converter (RSC). Furthermore for controlling Grid-Side Converter (GSC) system a conventional Direct Power Control (DPC) strategy will be compared with Fuzzy Direct Power Control (F-DPC) for controlling Active and reactive power flow exchanged with grid. Simulation results on a 2 MW DFIG system using MAT-LAB/Simulink are provided to demonstrate the effectiveness and robustness of the proposed control strategy during variations of active and reactive power, rotor speed, and converter dc link voltage.

The aim of this paper is to compare two different control structures. The Simple Direct Power Control (DPC) and the Direct Power Control with Space Vector Modulation (DPC- SVM) for two level converter applications. The first strategy (DPC) has been developed to control the instantaneous active and reactive power directly by selecting the optimum switching state of the converter. Applied to the Pulse Width Modulation (PWM) converter its main feature is to improve the total power factor and efficiency, even harmonics components existence. In the second structure, the active and reactive powers are used as (PWM) control vari- ables instead of the three-phase line currents usually used in other techniques. It is shown that DPC-SVM exhibits several properties; good dynamic response, constant switching fre- quency, and in particular it provides a sinusoidal line currents. Simulation and experimental results has shown that both control structures achieve good performances. DOI: http://dx.doi.org/10.11591/ijece.v4i3.6074

This paper proposes basic concepts of a fixed speed wind turbine (FSWT), as an introduction to a modern wind turbine concept; also, energy extraction from the wind turbine, in order to highlight the utility of the DPC in the field of the quality of the electric power. The VOC will be compared with structure known as DPC [1] applied to IG wind turbine connected to the network using back-to-back PWM converters. The theoretical principle of this method is discussed. From the simulation results, it is shown that DPC-2L displays several features, such as a simple algorithm and good dynamic response. The turbine side converter is controlled by the structure known Indirect Field Oriented Control (IFOC) in tow case [2]. Both VOC and DPC are simulated using MATLAB software to illustrate the performance of each technic.