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Abstract Power quality is a crucial determinant for integrating wind energy into the electrical grid. This integration necessitates compliance with certain standards and levels. This study presents cascadedfuzzy power control (CFPC) for a variable-speed multi-rotor wind turbine (MRWT) system. Fuzzy logic is a type of smart control system already recognized for its robustness, making it highly suited and reliable for generating electrical energy from the wind. Therefore, the CFPC technique is proposed in this work to control the doubly-fed induction generator (DFIG)-based MRWT system. This proposed strategy is applied to the rotor side converter of a DFIG to improve the current/power quality. The proposed control has the advantage of being model-independent, as it relies on empirical knowledge rather than the specific characteristics of the DFIG or turbine. Moreover, the proposed control system is characterized by its simplicity, high performance, robustness, and ease of application. The implementation of CFPC management for 1.5 MW DFIG-MRWT was carried out in MATLAB environment considering a variable wind speed. The obtained results were compared with the direct power control (DPC) technique based on proportional-integral (PI) controllers (DPC-PI), highlighting that the CFPC technique reduced total harmonic distortion by high ratios in the three tests performed (25%, 30.18%, and 47.22%). The proposed CFPC technique reduced the response time of reactive power in all tests by ratios estimated at 83.76%, 65.02%, and 91.42% compared to the DPC-PI strategy. Also, the active power ripples were reduced by satisfactory proportions (37.50%, 32.20%, and 38.46%) compared to the DPC-PI strategy. The steady-state error value of reactive power in the tests was low when using the CFPC technique by 86.60%, 57.33%, and 72.26%, which indicates the effectiveness and efficiency of the proposed CFPC technique in improving the characteristics of the system. Thus this control can be relied upon in the future.

Power quality is a crucial determinant for integrating wind energy into the electrical grid. This integration necessitates compliance with certain standards and levels. This study presents cascadedfuzzy power control (CFPC) for a variable-speed multi-rotor wind turbine (MRWT) system. Fuzzy logic is a type of smart control system already recognized for its robustness, making it highly suited and reliable for generating electrical energy from the wind. Therefore, the CFPC technique is proposed in this work to control the doubly-fed induction generator (DFIG)-based MRWT system. This proposed strategy is applied to the rotor side converter of a DFIG to improve the current/power quality. The proposed control has the advantage of being model-independent, as it relies on empirical knowledge rather than the specific characteristics of the DFIG or turbine. Moreover, the proposed control system is characterized by its simplicity, high performance, robustness, and ease of application. The implementation of CFPC management for 1.5 MW DFIG-MRWT was carried out in MATLAB environment considering a variable wind speed. The obtained results were compared with the direct power control (DPC) technique based on proportional-integral (PI) controllers (DPC-PI), highlighting that the CFPC technique reduced total harmonic distortion by high ratios in the three tests performed (25%, 30.18%, and 47.22%). The proposed CFPC technique reduced the response time of reactive power in all tests by ratios estimated at 83.76%, 65.02%, and 91.42% compared to the DPC-PI strategy. Also, the active power ripples were reduced by satisfactory proportions (37.50%, 32.20%, and 38.46%) compared to the DPC-PI strategy. The steady-state error value of reactive power in the tests was low when using the CFPC technique by 86.60%, 57.33%, and 72.26%, which indicates the effectiveness and efficiency of the proposed CFPC technique in improving the characteristics of the system. Thus this control can be relied upon in the future. [ABSTRACT FROM AUTHOR]

The power generated by photovoltaic (PV) systems is influenced by environmental factors. This variability hampers the control and utilization of solar cells' peak output. In this study, a single-stage grid-connected PV system is designed to enhance power quality. Our approach employs fuzzy logic in the direct power control (DPC) of a three-phase voltage source inverter (VSI), enabling seamless integration of the PV connected to the grid. Additionally, a fuzzy logic-based maximum power point tracking (MPPT) controller is adopted, which outperforms traditional methods like incremental conductance (INC) in enhancing solar cell efficiency and minimizing the response time. Moreover, the inverter's real-time active and reactive power is directly managed to achieve a unity power factor (UPF). The system's performance is assessed through MATLAB/Simulink implementation, showing marked improvement over conventional methods, particularly in steady-state and varying weather conditions. For solar irradiances of 500 and 1,000 W/m2, the results show that the proposed method reduces the total harmonic distortion (THD) of the injected current to the grid by approximately 46% and 38% compared to conventional methods, respectively. Furthermore, we compare the simulation results with IEEE standards to evaluate the system's grid compatibility. [ABSTRACT FROM AUTHOR]

In recent years, the pulse-width-modulation (PWM) converter has been found to have extensive applications in renewable energy, industrial fields, and others. The high efficiency requirement is crucial to operating a PWM rectifier in various applications, in addition to the fundamental control objectives of sinusoidal grid currents and the correct DC bus voltage. Additionally, in practical application, another issue arises when the grid voltage frequently experiences distortion, leading to a distorted grid current and a significant rise in total harmonic distortion (THD). To resolve these problems, a model predictive virtual flux-based direct power control (MPVFDPC) with improved power loss performance is proposed based on an integrated switching state predetermination strategy. The proposed MPVFDPC for PWM rectifier inherits the merits of both virtual flux control and direct power control, which have fast dynamic performance and the grid current THD is considerably decreased under distorted grid voltage states. The proposed technique aims to minimize switching loss under ideal and distorted grid voltage states by exploiting the discontinuous modulation concept by using a switching state predetermination strategy. The MPVFDPC with switching state predetermination strategy is proven by employing it in experiments as well as simulations in comparison with previous models: predictive direct power control (Conv. MPDPC) and conventional MPVFDPC (Conv. MPVFDPC). The acquired waveforms and quantitative data are employed to prove the effectiveness of the developed algorithm. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper focuses on modeling, control and power quality improvement of a microgrid connected system. This last was designed as a multi-converter system with Wind Turbine driven Permanent Magnet Synchronous Generator, and lithium ion Battery Storage Energy System. These sources are connected by a continuous bus to a nonlinear load through a DC /AC converter and three-phases multi-functional voltage source inverter. Where, wind systems are considered as primary power resource, and the grid is used for the effect of consumption of the overage power available from sources, when the battery has been fully charged. Multi Functional Voltage Source Inverter is used to ameliorate the performance of the proposed system, guaranteeing both reactive power and harmonic compensation. Moreover an intelligent control by fuzzy logic control algorithm are managed In order to extract the maximum power from wind turbine, to guarantee an effective storage management, this about the DC side. For the AC side a direct power control strategy with fuzzy logic algorithm have been used. The simulation of the system solution is carried out in Matlab/Simulink. The obtained simulation results show that the technique of fuzzy logic furnish the best solution in term of robustness, optimization performance, low THD and fast dynamic response.

Abstract The paper proposes a nonlinear controller called dual super-twisting sliding mode command (DSTSMC) for controlling and regulating the rotor side converter (RSC) of multi-rotor wind power systems that use doubly-fed induction generators. It was proposed that this controller be developed as an alternative to the direct power control (DPC), which makes use of a pulse width modulation (PWM) strategy to regulate the RSC's functioning. Overcoming the power/current quality issue with the proposed technique (DPC-DSTSMC-PWM) is characterized by great robustness and excellent performance. The designed strategy was contrasted with the standard method of control and other methods already in use. So, the unique proposed control strategy’s robustness, performance, efficiency, and efficacy in enhancing system characteristics were tested and validated in Matlab/Simulink. In both tests, the proposed method resulted in significant improvements, reducing active power ripples by 83.33%, 57.14%, and 48.57% in the proposed tests. When compared with the traditional regulation method, the reduction rates of reactive power ripples are 64.06%, 52.47%, and 68.7% in the tests. However, in contrast to the conventional method, the proposed tests showed a decrease of between 72.46%, 50%, and 76.22% in the value of total harmonic distortion (THD) of the provided currents. These ratios show how effective the proposed plan is in ameliorating and enhancing aspects of the energy system.

To effectively eliminate the impacts of both matched and mismatched power disturbances in a three-phase PWM rectifier, this paper proposes a robust direct power control (RDPC) method with a single-loop control structure. Firstly, a nonlinear power model of the three-phase PWM rectifier is established. Then, using the exact feedback linearization method, a linearized power model including matched and mismatched power disturbances is derived and achieves the decoupling of active and reactive power. Secondly, to regulate the DC bus voltage, a sliding-mode controller (SMC) combined with a nonlinear disturbance observer (NDO) is proposed. The proposed SMC combined with an NDO (SMC + NDO) method features a single-loop control structure, which enables a faster response and simpler structure compared to the dual-loop DPC method. By incorporating estimated mismatched power disturbance into the sliding-mode surface, it overcomes the SMC's defect in incompletely suppressing mismatched disturbances and enables the simultaneous regulation of voltage and active power. Additionally, it effectively reduces sliding-mode chattering. To regulate reactive power, a sliding-mode controller based on the exponential convergence law is designed to suppress matched reactive power disturbances. Finally, the simulation and experimental comparative results demonstrate that the proposed controller exhibits stronger robustness against matched and mismatched power disturbances, as well as a better performance under the constant power load (CPL). [ABSTRACT FROM AUTHOR]

The paper proposes a nonlinear controller called dual super-twisting sliding mode command (DSTSMC) for controlling and regulating the rotor side converter (RSC) of multi-rotor wind power systems that use doubly-fed induction generators. It was proposed that this controller be developed as an alternative to the direct power control (DPC), which makes use of a pulse width modulation (PWM) strategy to regulate the RSC's functioning. Overcoming the power/current quality issue with the proposed technique (DPC-DSTSMC-PWM) is characterized by great robustness and excellent performance. The designed strategy was contrasted with the standard method of control and other methods already in use. So, the unique proposed control strategy's robustness, performance, efficiency, and efficacy in enhancing system characteristics were tested and validated in Matlab/Simulink. In both tests, the proposed method resulted in significant improvements, reducing active power ripples by 83.33%, 57.14%, and 48.57% in the proposed tests. When compared with the traditional regulation method, the reduction rates of reactive power ripples are 64.06%, 52.47%, and 68.7% in the tests. However, in contrast to the conventional method, the proposed tests showed a decrease of between 72.46%, 50%, and 76.22% in the value of total harmonic distortion (THD) of the provided currents. These ratios show how effective the proposed plan is in ameliorating and enhancing aspects of the energy system. [ABSTRACT FROM AUTHOR]

Numerous control strategies are used to optimize the performance of the three-phase rectifier. Sliding Mode Control (SMC) is chosen for its robustness, fast response, high-efficiency control, finite-time convergence, and other features. Several SMC methods utilized with three-phase rectifiers are outlined in this review study. This study is divided into two main parts; the first part discusses the technique used to optimize the performance of the rectifier, while the second part discusses the SMC algorithms used to enhance the performance of the rectifier. In addition to their theoretical components, this review paper investigates the practical implementation challenges of SMCs for three-phase rectifiers. This paper discusses the optimization parameters of SMC and stability and load fluctuation in the rectifier system. It introduces state-of-the-art algorithms that enhance the rectifier’s dynamic performance, including the adaptive and observation algorithms. This paper is vital for engineers, researchers, and experts focusing on the SMC of three-phase rectifiers. To our knowledge, no similar review of three-phase rectifiers is available for SMC. Finally, a research gap is identified –as far as we know, no predefined time (free-will arbitrary time) SMC algorithm is used to control the performance of any power electronic device, such as a three-phase rectifier. This active rectifier is used in our project to optimize the power system for the alternator used in our unmanned ground vehicle (UGV) as an oil palm autonomous grabber.

Active front-end (AFE) rectifiers are a well-known solution in industries due to bidirectional power flow, sinusoidal line currents, and dc-link voltage adjustment. Typically, in three-phase AFE rectifiers, the power is distributed evenly among the phase legs, aiming for a natural balancing of aging over time. However, uneven thermal stress caused by different switching frequencies or design of cooling system and prior replacement of failure power switches might create an unavoidable aging mismatch between phase legs of AFE rectifier. In this article, a per-phase model predictive direct power control with offset voltage injection is proposed. The proposed method notably reduces power loss of the weakest phase to improve the lifespan of circuit and reduce maintenance costs. The power components of the AFE rectifier are regulated utilizing predicted rectifier voltages, which are changed by adding proper zero-sequence signal to decrease losses in the most aging leg. The minimum power loss of the weakest leg involves avoiding changing the corresponding switching state for two-thirds of the source period. Simulations and experiments are conducted to validate the developed technique.

This new paper describes an experimental investigation of a proportional-integral (PI) controller that uses feedback control to regulate an energy system that uses multi-rotor wind energy systems. Pulse width modulation (PWM) is used by the proposed controller to control the power of the doubly-fed induction generator controlled by direct power control (DPC), which is intended to regulate and control the inverter. The proposed strategy differs from the traditional DPC strategy. The proposed control was studied in the case of variable wind speed, where the MATLAB and Dspace 1104 environment was used to implement this proposed feedback PI (FPI) controller, with a comparison with the proposed control technique and some existing works. The suggested FPI controller outperforms the traditional controller and certain other controllers in terms of lowering energy ripples, overshoot, steady-state error (SSE), response time, and the total harmonic distortion (THD) of supplied system currents, as demonstrated by experimental and simulation results. The THD value of current was reduced by 64.86% and 69.44% in the two proposed tests compared to the traditional DPC technique. Also, the value of ripples and overshoot of active power was reduced compared to the DPC method by 95.42% and 90.86%, respectively, in the case of step wind speeds. Moreover, ripples and SSE of reactive powers compared to the DPC technique were reduced by 37.51% and 84.13%, respectively. These high ratios indicate the high performance of the proposed DPC-FPI technique in enhancing the features of the system in contrast to the conventional DPC technique.

Nowadays, active rectifiers are increasingly used, particularly in grid-connected applications. The high efficiency and reliability of active rectifiers become crucial for increasing the system performance. Due to the lack of model predictive control methods considering the different aging levels among phase legs of rectifiers, this paper thus introduces a direct power control-based model predictive control for independent loss reduction in each phase of the active rectifier. Different from conventional techniques, the target of proposed model predictive direct power control scheme is lowering switching loss in the leg having highest aging level of active rectifier, resulting in increasing its corresponding lifetime and lifetime of entire rectifier. As opposed to the model predictive control method based on incorporating additional terms regarding switching loss in the cost function, a switching state preselection strategy is proposed in this study to determine clamping region and corresponding preselected switching state for the leg having highest aging level of active rectifier. The use of the proposed method lowers thermal stress in the leg having highest aging level and increases lifetime of active rectifier. Simulation and experimental results for the proposed technique are presented and compared with conventional model predictive direct power control method to validate the accuracy and feasibility of the proposed method.

This paper proposes a robust control based on the integral backstepping control (IBC) for power quality enhancement of micro-grid-connected photovoltaic (PV) system with battery energy storage systems (BESS), The DC side consists of a PV system and battery storage. As for the AC side, it consists of three phases of a multi-functional two-level voltage source inverter (MVSI) coupled to the electrical grid via an inductive filter, all feeding a non-linear load. The MVSI is controlled by a nonlinear direct power control (DPC) strategy with space vector modulation (SVM) and the proposed IBC technique. Using the proposed IBC technique to control the voltage of the DC link voltage loop, the active/reactive power loops of the grid, the compensation of the harmonic currents of the network, and the injection of the power of the PV battery into the grid, loop of the maximum power point tracking (MPPT) regardless of the random nature of weather changes and guarantees optimal power management system battery storage. Using simulation under the MATLAB environment, the proposed control system was validated and compared to the conventional strategies (proportional–integral controller and backstepping controller) in terms of success, performance, robustness, and efficiency. In addition to its ability to respond under any irradiation distortion and non-linear load unbalance.

Copyright of Control Theory & Applications / Kongzhi Lilun Yu Yinyong is the property of Editorial Department of Control Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the DC microgrid, aimed at the power flow problem of dual active bridge (DAB) converters and their connected energy storage systems, this paper proposed an accurate direct power control(ADPC)method. The introduced control approach ensured constant power transmission on both sides of the DAB converter and was characterized by high accuracy, fast dynamic response, and excellent stability. It overcame the limitations of traditional direct power control(DPC)methods, which were highly dependent on system parameters. The effectiveness of the ADPC method was verified through simulations using MATLAB/Simulink and real-world experimental platforms. When compared to traditional power PI control methods, the proposed ADPC method, according to simulation and experimental results, significantly improves the dynamic performance of output power, especially under conditions of abrupt changes in power setpoints, load shifts, and input voltage fluctuations. Moreover, the method is independent of system parameters, enhancing the control method's compatibility and portability. The proposed method shows promising application prospects in the field of electric energy dispatch control within DC power supply networks. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper deduces the quantitative relationship between the flux vectors and the power of power winding (PW) in brushless doubly‐fed reluctance generator (BDFRG). On this basis, the direct power control (DPC) theory of BDFRG is established, which makes up the deficiency that the DPC theory of BDFRG is only based on qualitative analysis in the existing literature. The power derivative expression is derived for accurately analyzing the effect of voltage vector of control winding (CW) on the power of PW, concluding that the control effect of DPC is related to the operation point of a BDFRG. The number of basic voltage vectors of CW connected with two‐level converter is limited, resulting that under some operation conditions, a BDFRG controlled by DPC could present a time interval where the power cannot be controlled satisfactorily. Therefore, the space vector modulation‐based direct power control (SVM‐DPC) strategy of BDFRG is proposed, which can solve the above problem and fix the switching frequency. Experimental results prove the correctness of the elaboration and the proposed method. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Active power filter (APF) can significantly compensate the current harmonics produced by nonlinear loads. To do this feature, harmonic detection beside harmonic generation play vital role. Direct power controller (DPC) has great harmony with instantaneous power compensation (PQ) algorithm as well as ability to eliminate internal current loops. In addition, deadbeat controller (DBC) has high compatibility for digital implementation, superior control performance and fast dynamic response. However, DBC suffers from time delay regarded to control action calculation and digital implementation. In this paper, a new deadbeat-based DPC method is proposed firstly to control and generates the harmonic currents of APF. Several simulations achieved in MATLAB/SIMULINK beside different experimental tests obtained from a DSP-based active power filter are conducted to illustrate and prove the effectiveness and superior performance of the proposed control system. As a result, the THD of grid current decreases from 22% to 3.2% under steady state where dynamic response under with/without compensation validate significant transient response lower than 5ms.

Introduction. For AC-DC conversion systems, the electrical systems typically use thyristor or diode bridge rectifiers, which have relatively poor performance. Nowadays, three-phase pulse-width modulation rectifiers are widely applied in various applications for their well-known intrinsic benefits, such as adjustable DC link voltage, unity power factor, bidirectional power flow and very low total harmonic distortion. Purpose. The objective of this work is to achieve better stability and dynamic performance using sliding mode strategy for control and observation. Methods. For that purpose, first a sliding mode controller is introduced on the DC-link side to ensure a fast and accurate response of the output load voltage. Then, the sliding mode approach is employed to control the quadrature and direct components of power to maintain the input power factor at unity. Finally, this approach is used to design two observers for grid voltage estimation and online variation of load resistance. To overcome the problem associated with the use of the classical low-pass filter, an adaptive compensation algorithm is used to compensate the attenuation of the amplitude and phase delay of the observed grid voltages. This algorithm is based on the use of the two low-pass filters in cascade and ensures the minimization of chattering. Results. Comparative studies have been carried out between sliding mode control method for controlling the three-phase AC-DC pulse-width modulation rectifier and other conventional techniques. The validation by simulation and the tests carried out gave very satisfactory results and proved the effectiveness and feasibility of the sliding mode for both control and observation of three phase pulse-width modulation rectifier.

Aiming at the problem of poor control effect of grid-side converter of doubly-fed induction generator due to load change and filter parameter perturbation, a double closed-loop control strategy of grid-side converter based on extended state observer (ESO) and sliding mode control is proposed. The inner loop adopts ESO-based sliding mode direct power control with power as the state variable, and the outer loop adopts ESO-based sliding mode control with voltage square as the state variable. Using ESO to estimate the system state variables and lumped uncertainties including unmodeled dynamics, load variation and filter parameter perturbation of the system, the sliding mode control method can be designed without the accurate mathematical model of the system to realize the robust control of grid-side converter in a complex environment. In addition, the power difference feedforward link is introduced to reduce the impact of the nonlinearity of the outer loop sliding mode control when the load changes. Finally, two examples of load charge and filter parameter perturbation are simulated, and the results show that the proposed control strategy has stronger robustness in the complex environment than traditional vector control and sliding mode control.

In recent years, the pulse-width-modulation (PWM) converter has been found to have extensive applications in renewable energy, industrial fields, and others. The high efficiency requirement is crucial to operating a PWM rectifier in various applications, in addition to the fundamental control objectives of sinusoidal grid currents and the correct DC bus voltage. Additionally, in practical application, another issue arises when the grid voltage frequently experiences distortion, leading to a distorted grid current and a significant rise in total harmonic distortion (THD). To resolve these problems, a model predictive virtual flux-based direct power control (MPVFDPC) with improved power loss performance is proposed based on an integrated switching state predetermination strategy. The proposed MPVFDPC for PWM rectifier inherits the merits of both virtual flux control and direct power control, which have fast dynamic performance and the grid current THD is considerably decreased under distorted grid voltage states. The proposed technique aims to minimize switching loss under ideal and distorted grid voltage states by exploiting the discontinuous modulation concept by using a switching state predetermination strategy. The MPVFDPC with switching state predetermination strategy is proven by employing it in experiments as well as simulations in comparison with previous models: predictive direct power control (Conv. MPDPC) and conventional MPVFDPC (Conv. MPVFDPC). The acquired waveforms and quantitative data are employed to prove the effectiveness of the developed algorithm.

The direct power control (DPC) technique has been proposed as an alternative method to sophisticated current control techniques in order to synthesise the instantaneous active and reactive powers fed by the inverter into the grid. The method selects the voltage vector of the inverter based on the quantised values of the instantaneous active and reactive power errors and thereby controls the power exchange between inverter and the Point of Common Coupling (PCC) directly. The method has better dynamic performance, an inherent decoupling of active and reactive powers and robustness against parameter variations. However, the application of DPC to shunt active power filter (SAPF) requires high sampling frequency in the digital controller and at the same time suffers from the issue of the large variation in the switching frequency. This work proposes implementation of a modified switching table of DPC using multisector Discrete Space Vector Modulation(DSVM) concept for the SAPF to alleviate the problem of high sampling frequency requirement and variation in switching frequency and reduce burden on the controller. The performance of the method is evaluated in MATLAB Simulink® environment, verified with 2 kVA laboratory prototype under various load conditions and compared with constant switching frequency-predictive deadbeat DPC method. [ABSTRACT FROM AUTHOR]

The Direct power control and vector control of DFIG has known advantages, but certain disadvantages like steady state performance and transient performance of the system still persist. In order to overcome these, a novel technique based on Improved Sensorless Rotor Position Computational Algorithm with Integrated Direct Power and Vector Control (IDPVC) for S-VSC interfaced DFIG is proposed in this work. The advantages of both vector control and direct power control techniques are addressed in this method. This proposed IDPVC control minimizes the real and reactive power ripples at steady state and total harmonic distortion in stator current. In the proposed control, data acquired from sensorless rotor position computation makes the system more stable and avoids the sensor maintenance and feedback errors. The proposed system is tested for a 3.73 kW DFIG and compared with a benchmark DPC control of single VSC based DFIG. The results show the effectiveness of the approach under various wind speed conditions and found to be satisfactory. [ABSTRACT FROM AUTHOR]

This study proposes a simplified super-twisting algorithm (SSTA) control strategy for improving the power quality of grid-connected photovoltaic (PV) power systems. Some quality issues are considered in this study including the power factor, reducing the total harmonic distortion (THD) of current, compensating the reactive power, and injecting at the same time the energy supplied by the PV system into the grid considering non-linear load. This improvement is achieved by two topologies; controlling both the boost DC–DC converter and the DC–AC inverter that links the PV system to the grid. The DC–DC converter is controlled using proportional-integral (PI) and SSTA to maximize the power generated from the PV panel regardless of its normal and abnormal conditions, while the DC–AC inverter is employed to direct power control strategy with modified space vector modulation using the phase-locked loop (PLL) technique of a three-level neutral-point-clamped (NPC) inverter based on the proposed strategies (PI and SSTA). In addition, a shunt active power filter (SAPF) is used to connect the PV system to the AC grid and feed a non-linear load. To validate the simulation results presented in this paper using Matlab software, a comparative study between the PI controller and the SSTA is presented. The results show the effectiveness and moderation of the suggested SSTA technique in terms of feasibility, tracking performance, less power ripple, dynamic response, THD value, overshoot, steady-state error, and robustness under varying irradiation, temperature, and non-linear conditions. [ABSTRACT FROM AUTHOR]

This work provides regulation of active and reactive power for asynchronous generator-based multi-rotor wind power (MRWP) systems using a synergetic control based on fractional order control theory. The traditional synergetic control theory achieves an undesirable chattering effect, which can damage the system. For this, it is relevant to combine the traditional synergetic control theory with fractional order control to avoid these drawbacks. Two control schemes are proposed, analyzed, and compared: traditional direct power control (DPC) and DPC based on fractional-order synergetic controllers, the latter needs only the information of the sliding surface. Their characteristics are compared in terms of current quality, active and reactive power reference tracking, robustness against generator parameter variations, and power ripple. Simulation results using Matlab software have demonstrated the characteristics and robustness of the suggested DPC based on fractional-order synergetic controllers compared to the DPC because of its efficacy in improving the quality of power/current.

This paper proposes a direct power control scheme for an offshore wind turbine-driven surface-mounted permanent magnet synchronous generator with a full back-to-back converter situated onshore to decentralize the weight of the turbine. The proposed model is designed in a stationary reference frame and does not require a phase-locked loop as opposed to the traditional vector current control method. Simple feed-forward and feedback control loops are used in the proposed model to extract the maximum available wind power, maintain constant voltage at the coupling DC link, and ensure power injection into the electric network at unity power factor. Simulation results carried out in MATLAB/SIMULINK show that the proposed model has a fast transient response and steady-state performance consistent with the vector current control model. Furthermore, eigenvalue analysis results demonstrate that the proposed method’s performance is robust to variations in different system parasitic elements, even under both stiff and weak electric network conditions. These results also indicate that the back-to-back converter can operate effectively when located onshore close to the load center while the turbine is in close proximity offshore. This can be suitable for multiple specific offshore applications as it can potentially reduce the overall weight, volume, and cost of the offshore wind turbine infrastructure.

In this paper, a linearized time-invariant voltage-sensorless direct power control (DPC) with balanced and unbalanced dc-link voltage is proposed in a three-phase Vienna rectifier. To achieve voltage sensorless with unbalanced dc-link voltage, the control architecture consists of three sub-architectures, including 1) linear time-invariant direct power control; 2) virtual flux, input active power and reactive power estimators; 3) zero crossing distortion and capacitor voltage unbalance compensations under single carrier pulse-width modulation (PWM) operation. The proposed method transfers the system from linear time-varying system to linear time-invariant system by algebraic transformation, which makes the design of the controller more directly. The proposed direct power control method can reduce system cost and lower input current total harmonic distortion and does not require the use of phase-locked loop (PLL). A 2.4kW prototype is constructed and some simulation and experimental results are offered to verify the validity of the proposed method.

The integration of wind energy systems into the electric grid has become inevitable despite the many problems associated with this integration. Most of these problems are due to variations in wind speed. The problems are for example oscillations in the power generated, which implies the lack of guarantee of obtaining the maximum energy and the ripple in the electromechanical torque of the generator. This work aims at mitigating these problems for wind energy conversion system-driven doubly-fed induction generator (DFIG), which is the main wind turbine utilized for energy applications. This mitigation is performed through direct reactive and active powers control of the DFIG using an artificial neural network. A DSP (Digital Signal Processor-dSPACE DS1104) was used to experimentally test the proposed strategy. The dynamic performances of the controlled generator are analyzed by using the designed intelligent control strategy in the case of variable wind speeds and upon sudden change of the active power demand. Based on the obtained experimental results, it can be said that the designed intelligent control strategy outperforms traditional methods like direct power (DPC) and vector control in terms of reducing the current harmonics, and torque ripples, and enhancing dynamic response.

In this paper, a three-phase shunt active power filter (SAPF) controller with a fully digital implementation is presented. The main goal of this contribution is to implement a digital direct power control (DDPC) algorithm without phase-locked-loop (PLL) for SAPF. This algorithm is intended for power quality improvement and current harmonic elimination. The controller introduced in this paper is cost-effective, has a fast-dynamic response, and has a simple hardware implementation. In order to comply with the above specifications, a dedicated controller has been conceived and fully implemented within a field-programmable gate array (FPGA) device. This FPGA-based controller integrates the whole signal-processing functions needed to drive the SAPF, as well as an original method for sector identification. The intended controller provides the desired power references to select the optimal switching sequences. The switching orders follow the grid reference to drive the voltage source inverter (VSI), so the SAPF achieves good performances while ensuring balanced overall supply currents, unity power factor, and reduced harmonic load currents. The proposed digital implementation achieves a valuable compromise between fast dynamic response, minimum execution time, and reduced FPGA resources, through a simple hardware design implementation. The entire system is developed and simulated using VHDL and VHDL-AMS languages.

Model predictive control (MPC) is a powerful and widely used technique to address the control challenges in power converters as the grid interface for renewable energy systems. This technique combines closed-loop control with error and control effort minimization; however, its design is challenging, and we know little about how the controller parameters affect the closed-loop performance of grid-connected voltage source converters. In this study, we applied an MPC direct power control with modulation for a grid-connected power converter with an inductive filter. For the controller design, we proposed an initial set based on the power converter’s nominal setup. Then, we define the range of settings to guarantee stability by analyzing the closed-loop poles of the system. The fine-tuning to improve the performance can be identified visually using the performance maps built from simulations of the control system, simultaneously sweeping the time horizons of the predictive model and the weight factors of the cost function. Experimental results on a low-power bench demonstrate the excellent performance of the designed controller, following and even outperforming the classical proportional-integral (PI) controller and other advanced control techniques.

This paper presents a new fuzzy direct power control of double-fed induction generators (DFIG) in the wind power system. The most important issue in the application of DFIG generators is proper control of the active and reactive powers of these generators, which are generally carried out by vector control or direct torque/power control methods. Direct power control (DPC) directly controls the active and reactive powers of the stator, and stems from results from direct torque control. To use the vector control method, it is necessary to use conventional PI controllers the main disadvantage being the controller robustness due to the nonlinear behavior of the wind turbine and blade oscillations, and it is unavoidable that after a while, the controller's coefficients need to be updated. Therefore, the main purpose of this paper is to present a direct power control method based on fuzzy construction to overcome the mentioned problem. Simulation results of the proposed strategy are extracted under different performance conditions, and these results are compared with the conventional vector-oriented control method. These comprehensive results exhibit the effectiveness of the proposed fuzzy DPC method for the DFIGs based wind power systems.

Direct power control (DPC) has gained increasing attention in recent years as a simple and efficient control strategy for pulse width modulation (PWM) rectifiers. In this paper, the idea of DPC is introduced into the three-phase coupled inductor-based bipolar-output active rectifier (TCIBAR) for the first time, and a virtual vector-based direct power control (VVB-DPC) strategy is proposed for TCIBAR to realize the bipolar DC power supply for more electric aircraft (MEA). First, the mathematical model of the TCIBAR is deduced, and the basic principle of the classic DPC strategy is reviewed. On this basis, the limitations of the classic DPC strategy in TCIBAR control are analyzed. Second, a set of virtual vectors are derived to establish a novel virtual-vector switching table. Based on the virtual-vector switching table, the hysteresis power control of TCIBAR can be realized without affecting the DC-side neutral-point potential of TCIBAR. Finally, a neutral-point potential control method based on DPC architecture is studied and integrated into the VVB-DPC strategy to maintain the bipolar DC voltage balance of TCIBAR under unbalanced load conditions. The VVB-DPC strategy is experimentally studied on a TCIBAR prototype, and the experimental results verify the feasibility and effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

This paper presents a novel direct power control (DPC) strategy based on an optimized sector division for a three-phase coupled inductor-based bipolar output active rectifier (TCIBAR) applied in more electric aircraft (MEA). First, based on the instantaneous power theory, the power model of the TCIBAR is built in the synchronous rotating coordinate system. Second, to implement the hysteresis power control of TCIBAR without causing the runaway of the zero-sequence current in the three-phase coupled inductor (TCI), a set of new voltage vectors that have the same zero-sequence voltage (ZSV) component are synthesized and adopted in the proposed DPC strategy. Third, by quantitatively analyzing the effect of the new synthesized voltage vectors on the power variation of TCIBAR, an optimized sector division method is proposed to improve the accuracy of power control and reduce the phase current harmonics in TCIBAR. Finally, to maintain the voltage balance of the bipolar dc ports in TCIBAR, voltage balance control is studied in the proposed DPC strategy. The proposed DPC strategy is researched on an experimental platform of TCIBAR, and the results show that the proposed DPC strategy is feasible and has good static and dynamic performance. [ABSTRACT FROM AUTHOR]

This paper proposes a multi-vector predictive direct power control (P-DPC) for grid-tied T-type three-level inverters with optimized vector application time calculations. The conventional multi-vector P-DPC suffers from the problems of a heavy computational burden and a tedious adjustment process for the weighting factor. To reduce the computational burden, this paper proposes a new space vector division method. The proposed method can reduce the number of candidate vectors and the number of iterations for the cost function. To avoid the need for adjusting the weighting factor, the redundant small vectors are utilized to balance the neutral point voltage. In addition, the Lagrange multiplier method is introduced to optimize the calculation of the prediction vector application time, which improves the control accuracy. Finally, the effectiveness of the proposed method is verified in a hardware-in-the-loop platform. [ABSTRACT FROM AUTHOR]

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Introduction. For AC-DC conversion systems, the electrical systems typically use thyristor or diode bridge rectifiers, which have relatively poor performance. Nowadays, three-phase pulse-width modulation rectifiers are widely applied in various applications for their well-known intrinsic benefits, such as adjustable DC link voltage, unity power factor, bidirectional power flow and very low total harmonic distortion. Purpose. The objective of this work is to achieve better stability and dynamic performance using sliding mode strategy for control and observation. Methods. For that purpose, first a sliding mode controller is introduced on the DC-link side to ensure a fast and accurate response of the output load voltage. Then, the sliding mode approach is employed to control the quadrature and direct components of power to maintain the input power factor at unity. Finally, this approach is used to design two observers for grid voltage estimation and online variation of load resistance. To overcome the problem associated with the use of the classical low-pass filter, an adaptive compensation algorithm is used to compensate the attenuation of the amplitude and phase delay of the observed grid voltages. This algorithm is based on the use of the two low-pass filters in cascade and ensures the minimization of chattering. Results. Comparative studies have been carried out between sliding mode control method for controlling the three-phase AC-DC pulse-width modulation rectifier and other conventional techniques. The validation by simulation and the tests carried out gave very satisfactory results and proved the effectiveness and feasibility of the sliding mode for both control and observation of three phase pulse-width modulation rectifier. [ABSTRACT FROM AUTHOR]

To improve the fault redundancy capability for the high reliability requirement of a brushless doubly-fed generation system applied to large offshore wind farms, the control winding of a brushless doubly-fed reluctance generator is designed as an open-winding structure. Consequently, the two ends of the control winding are connected via dual three-phase converters for the emerging open-winding structure. Therefore, a novel fault-tolerant control strategy based on the direct power control scheme is brought to focus in this paper. Based on the direct power control (DPC) strategy, the post-fault voltage vector selection method is explained in detail according to the fault types of the dual converters. The fault-tolerant control strategy proposed enables the open-winding brushless doubly-fed reluctance generator (BDFRG) system to operate normally in one, two, or three switches fault of the converter, simultaneously achieving power tracking control. The presented results verify the feasibility and validity of the scheme proposed. [ABSTRACT FROM AUTHOR]

Grid-forming (GFM) converters can provide inertia support for power grids through control technology, stabilize voltage and frequency, and improve system stability, unlike traditional grid-following (GFL) converters. Therefore, in future “double high” power systems, research on the control technology of GFM converters will become an urgent demand. In this paper, we first introduce the basic principle of GFM control and then present five currently used control strategies for GFM converters: droop control, power synchronization control (PSC), virtual synchronous machine control (VSM), direct power control (DPC), and virtual oscillator control (VOC). These five strategies can independently establish voltage phasors to provide inertia to the system. Among these, droop control is the most widely used strategy. PSC and VSM are strategies that simulate the mechanical characteristics of synchronous generators; thus, they are more accurate than droop control. DPC regulates the active power and reactive power directly, with no inner current controller, and VOC is a novel method under study using an oscillator circuit to realize synchronization. Finally, we highlight key technologies and research directions to be addressed in the future.

Direct power control (DPC) is among the most popular control schemes used in renewable energy because of its many advantages such as simplicity, ease of execution, and speed of response compared to other controls. However, this method is characterized by defects and problems that limit its use, such as a large number of ripples at the levels of torque and active power, and a decrease in the quality of the power as a result of using the hysteresis controller to regulate the capacities. In this paper, a new idea of DPC using artificial neural networks (ANNs) is proposed to overcome these problems and defects, in which the proposed DPC of the doubly fed induction generators (DFIGs) is experimentally verified. ANN algorithms were used to compensate the hysteresis controller and switching table, whereby the results obtained from the proposed intelligent DPC technique are compared with both the classical DPC strategy and backstepping control. A comparison is made between the three proposed controls in terms of ripple ratio, durability, response time, current quality, and reference tracking, using several different tests. The experimental and simulation results extracted from dSPACE DS1104 Controller card Real-Time Interface (RTI) and Matlab/Simulink environment, respectively, have proven the robustness and the effectiveness of the designed intelligence DPC of the DFIG compared to traditional and backstepping controls in terms of the harmonic distortion of the stator current, dynamic response, precision, reference tracking ability, power ripples, robustness, overshoot, and stability. [ABSTRACT FROM AUTHOR]

This paper proposes a new technique of maximum power point tracking (MPPT) for a photovoltaic (PV) system connected to three phase grids under partial shading condition (PSC), based on a new combined perturb and observe (P&O) with scanning algorithm. This new algorithm main advantages are the high-speed tracking compared to existing algorithms, high accuracy and simplicity which makes it ideal for hardware implementation. Simulation was carried on MATLAB/Simulink. Results showed the effectiveness in speed and accuracy of our algorithm over the existing ones either during standard condition (STC) or PSC. Furthermore, conventional direct power control (DPC) was applied to synchronize successfully the injected power with the grid, which makes our algorithm global and works efficiently under severe conditions. [ABSTRACT FROM AUTHOR]