Deadbeat Current Control in Grid-Connected Inverters: A Comprehensive Discussion (original) (raw)
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IEEE Access
The control of voltage source converters (VSCs) is now implemented on digital microprocessors. This digitalization has the drawback of time delay in the control loop. The goal of this research work was to investigate improvements that can be obtained from the combination of model-based and model-free time-delay compensation approaches. Deadbeat control (DBC) from model-based techniques and the method of moving the control variable's sampling instants, or the pulse-width modulation (PWM) updating instants, from model-free time-delay compensation techniques, were put together as the proposed new method of time-delay compensation in this study. These controllers were thoroughly examined in terms of control algorithm design, system stability analysis, and sensitivity analysis of plant parameter perturbations. In addition, thorough Simulink-based computer simulations were conducted in this work to assess the performance of each controller. The proposed method compensated about 80 µs as compared with the time delay compensated by the conventional single-sampling method. This research work was limited to simulations only; hence, conducting experiments to further validate this research work could be a direction for further research.
Novel deadbeat power control strategy for grid connected systems
Journal of Electrical Systems and Information Technology, 2015
This paper introduces a novel approach for power control of three phase voltage source inverter (VSI) in grid connected distribution generation system. In this approach, the control of active and reactive power is based on deadbeat control strategy. First, the difference between the reference and actual currents are introduced in different approach. Then current to power substitutions are carried out to obtain direct relationship between the required inverter voltage and instantaneous power errors. There is no need for coordinate transformation or PLL, where the required inverter voltage vector calculations carried out in α-β stationary reference frame. The proposed technique introduces two cross coupling components in the control function. Including these two components, the controller can achieve nearly zero steady-state tracking error of the controlled variables. To obtain fixed switching frequency operations, space vector modulation (SVM) is used to synthesize the required inverter voltage vector and to generate the switching pulses for the VSI. The proposed strategy has the simplicity of the direct power control (DPC) technique and doesn't require any current control loops. The proposed strategy is experimentally implemented using fixed-point microcontroller. Simulation and experimental results are presented to confirm the superiority of the proposed strategy.
Hybrid Current Control Technique Applied to Grid Connected Inverters
2015
Voltage source inverters (VSI) with LCL filter play an important role in grid connected applications. Features such as bidirectional power flow, reduced filter volume and good electromagnetic compatibility performance make this a suitable solution for such applications. However, the current control strategy becomes more complex if compared to VSIs with simple inductive filters. Among various current controllers, the proportional+resonant (P+R) and deadbeat predictive ones present interesting characteristics for steady-state and transient performance, respectively. This paper evaluates a hybrid current control technique, based on P+R and deadbeat controllers operating together, in order to achieve a good dynamic response and reduced steady state error and, thus, benefit from the merits of each of the individual controllers.
Energies, 2021
Power converters have turned into a critical and every-day solution for electric power systems. In fact, the incorporation of renewable energies has led towards the constant improvement of power converter topologies and their controls. In this context, over the last 10 years, model predictive control (MPC) is positioned as one the most studied and promising alternatives for power converter control. In voltage source inverters (VSI), MPC has only been applied in the inner current control loop, accelerating and improving its dynamic response, but as mentioned, has been limited only to the current control loop. The fastest of the MPC techniques is the Deadbeat (DB) control, and in this paper, it is proposed to employ DB control on the entire system, therefore accelerating the time response not only for the current loops, but also for voltage loops. At the same time, this avoids overshoots and overpower in order to protect the power converter, leading to the fastest dynamic response acc...
2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018
A multiple proportional resonant (PR) current regulator based dead-time effects compensation method for gridforming single-phase inverter is proposed. Most of dead-time effect studies are based on the polarity of the average inductor current. However, dead-time effect is eliminated at zerocrossing zone of the inductor current. Conventional dead-time compensation methods based on the polarity of the average inductor are not suitable for grid-forming single-phase inverter because of the large inductor current ripple and wide load range. In this paper, the dead-time effect considering ripple current is investigated and the relation between the load current and the range of the zero-crossing zone is discussed. Furthermore, the zero current clamping (ZCC) phenomenon and oscillation induced by dead-time are also discussed. In order to compensate the dead-time effects, a multiple PR current regulator based dadtime compensation method is proposed to reduce the voltage disturbance caused by dead-time effect in single-phase gridforming inverter. The simulation and experiment results show the validity of the analysis and the distortion of the inverter output voltage is eliminated. Index Terms-grid-forming single-phase inverter, dead-time effects, multiple PR regulator
Robust dead-beat current control for PWM rectifiers and active filters
IEEE Transactions on Industry Applications, 1999
This paper analyzes the stability limitations of the digital dead-beat current control applied to voltage-source threephase converters used as pulsewidth modulation rectifiers and/or active filters. In these applications, the conventional control algorithm, as used in drive applications, is not sufficiently robust, and stability problems may arise for the current control loop. The current loop is, indeed, particularly sensitive to any model mismatch and to the possibly incorrect identification of the model parameters. A detailed analysis of the stability limitations of the commonly adopted dead-beat algorithm, based on a discretetime state-space model of the controlled system, is presented. A modified line voltage estimation technique is proposed, which increases the control's robustness to parameter mismatches. The results of the theoretical analysis and the validity of the proposed modification to the control strategy are finally verified both by simulations and by experimental tests.
SN Applied Sciences
This paper proposes a control strategy for a grid-connected single-phase Active Front-End (AFE) rectifier that deals with both of ac-side sinusoidal current quality during steady state and dc-bus voltage fluctuations under transient operation issues. This control strategy consists of two control loops. The outer one is used for the control of the dc-bus voltage and is based on a PI controller. The inner loop is used for the control of the grid current and is based on a Deadbeat Predictive (DP) controller that operates with a fixed switching frequency. In order to prevent interactions between the two control loops, the outer control loop dynamic should be at least ten times lower than that of the inner control loop dynamic. For this purpose, a theoretical approach for computing the dynamic of the deadbeat predictive current control is described. Then, the dc-bus voltage controller is designed so that the following constraints are satisfied: (a) the bandwidth of the voltage control loop must be very low with regard to that of the current control loop to prevent interaction between them; (b) the third harmonic component of the grid current resulting from the double line frequency ripples of the measured dc-bus voltage has to be mitigated complying with standards, and (c) reducing the transient fluctuations of the dc-bus voltage caused by instantaneous and high level changes of the active power consumed by the dc load. Simulation and experimental results for the control algorithm validation are also presented and discussed.
An Overview on Current Control Techniques for Grid Connected Renewable Energy Systems
2012
Most type of renewable energy systems works in conjunction with the existing electrical grids. Also, inverter technology has an important role to have a safe and reliable grid interconnection operation of renewable energy systems. It is also necessary to generate a high quality power to the grid with reasonable cost. They also must be capable of provide high efficiency conversion with high power factor and low harmonic distortion. For this reason, the control policy must be considered. Therefore, the most important current control techniques are investigated in this paper. The ability of them to eliminate the steady state error, fast transient response and the possibility of compensation for low order harmonics is also discussed and compared to each other.
Penetration of grid connected inverters (GCI) has arisen in power systems due to increasing integration of renewable sources. However, restrictive grid codes require that renewable sources connected to the grid with power electronic systems must be properly connected and appropriate currents must be injected to support stability of the grid under grid faults. Simultaneous injection of symmetrical positive and negative sequence currents is mandatory to support stabilization of grid at the instant of grid faults. Conventional synchronously rotating frame dq current controllers are insufficient under grid faults due to low bandwidth of PI controllers. This paper proposes a new grid current control strategy for grid connected voltage source inverters under unbalanced grid voltage conditions. A proportional current controller with a first order low pass filter disturbance observer (DOb) is proposed which establishes positive sequence power requirements and independently control negative ...