scholarly journals An Improved Control Strategy for a Four-Leg Grid-Forming Power Converter under Unbalanced Load Conditions

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Mohammad Reza Miveh ◽  
Mohd Fadli Rahmat ◽  
Mohd Wazir Mustafa ◽  
Ali Asghar Ghadimi ◽  
Alireza Rezvani
Keyword(s):  
Reference Frame ◽  
Control Strategy ◽  
Tracking Error ◽  
Power Converter ◽  
Current Control ◽  
Voltage Source ◽  
Current Loop ◽  
Voltage Controller ◽  
Unbalanced Load ◽  
Load Conditions

This paper proposes an improved multiloop control strategy for a three-phase four-leg voltage source inverter (VSI) operating with highly unbalanced loads in an autonomous distribution network. The main objective is to balance the output voltages of the four-leg inverter under unbalanced load conditions. The proposed control strategy consists of a proportional-integral (PI) voltage controller and a proportional current loop in each phase. The voltage controller and the current control loop are, respectively, used to regulate the instantaneous output voltage and generate the pulse width modulation (PWM) voltage command with zero steady-state tracking error and fast transient response. A voltage decoupling feedforward path is also used to enhance the system robustness. Since the outer voltage loop operates in the synchronous reference frame, tuning and stability analysis of the PI controller is far from being straightforward. In order to cope with this challenge, the stationary reference frame equivalent of the voltage controller in the rotating frame is derived. Subsequently, a systematic design based on a frequency response approach is provided. Simulation results are also carried out using the DIgSILENT PowerFactory software to verify the effectiveness of the suggested control strategy.

scholarly journals Improved Voltage Unbalance and Harmonics Compensation Control Strategy for an Isolated Microgrid

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2688 ◽  
Author(s):  
Mohammad Jafar Hadidian Moghaddam ◽  
Akhtar Kalam ◽  
Mohammad Reza Miveh ◽  
Amirreza Naderipour ◽  
Foad H. Gandoman ◽  
...  
Keyword(s):  
Control Strategy ◽  
Power Converter ◽  
Phase Model ◽  
Nonlinear Load ◽  
Loop Control ◽  
Single Input Single Output ◽  
Three Phase ◽  
Control Scheme ◽  
Unbalanced Load ◽  
Load Conditions

This paper suggests an enhanced control scheme for a four-leg battery energy storage systems (BESS) under unbalanced and nonlinear load conditions operating in the isolated microgrid. Simplicity, tiny steady-state error, fast transient response, and low total harmonic distortion (THD) are the main advantages of the method. Firstly, a new decoupled per-phase model for the three-phase four-leg inverter is presented. It can eliminate the effect of power stage coupling on control design; thus, the three-phase four-leg power inverter can be viewed as three single input single output (SISO) control systems. Then, using an improved orthogonal signal generation method, the per-phase model of the four-leg inverter in the stationary and synchronous frame is derived. As the second step, a per-phase multi-loop control scheme for the four-leg inverter under unbalanced load conditions is suggested. The proposed control strategy has the ability to provide balanced output voltages under unbalanced load conditions by avoiding the need to deal with the symmetrical components. Finally, a multi-resonant harmonic compensator is used to actively prevent low-order harmonic currents to distort the output voltages of the three-phase four-leg grid-forming power converter. Simulations results are also presented to verify the performance of the suggested control strategy.

scholarly journals An improved synchronous reference frame current control strategy for a photovoltaic grid-connected inverter under unbalanced and nonlinear load conditions

PLoS ONE ◽  
2017 ◽  
Vol 12 (2) ◽  
pp. e0164856 ◽  
Author(s):  
Amirreza Naderipour ◽  
Abdullah Asuhaimi Mohd Zin ◽  
Mohd Hafiz Bin Habibuddin ◽  
Mohammad Reza Miveh ◽  
Josep M. Guerrero
Keyword(s):  
Reference Frame ◽  
Control Strategy ◽  
Current Control ◽  
Nonlinear Load ◽  
Synchronous Reference Frame ◽  
Grid Connected Inverter ◽  
Load Conditions

scholarly journals Indirect Effective Controlled Split Source Inverter-Based Parallel Active Power Filter for Enhancing Power Quality

Electronics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 892
Author(s):  
Poornima Udaychandra Panati ◽  
Sridhar Ramasamy ◽  
Mominul Ahsan ◽  
Julfikar Haider ◽  
Eduardo M.G. Rodrigues
Keyword(s):  
Fuzzy Logic ◽  
Power Quality ◽  
Fuzzy Logic Controller ◽  
Active Power ◽  
Current Control ◽  
Control Algorithms ◽  
Current Loop ◽  
Current Profile ◽  
Nonlinear Load ◽  
Load Conditions

The existing solutions for reducing total harmonic distortion (THD) using different control algorithms in shunt active power filters (SAPFs) are complex. This work proposes a split source inverter (SSI)-based SAPF for improving the power quality in a nonlinear load system. The advantage of the SSI topology is that it is of a single stage boost inverter with an inductor and capacitor where the conventional two stages with an intermediate DC-DC conversion stage is discarded. This research proposes inventive control schemes for SAPF having two control loops; the outer control loop regulates the DC link voltage whereas the inner current loop shapes the source current profile. The control mechanism implemented here is an effective, less complex, indirect scheme compared to the existing time domain control algorithms. Here, an intelligent fuzzy logic control regulates the DC link voltage which facilitates reference current generation for the current control scheme. The simulation of the said system was carried out in a MATLAB/Simulink environment. The simulations were carried out for different load conditions (RL and RC) using a fuzzy logic controller (FLC) and PI controllers in the outer loop (voltage control) and hysteresis current controller (HCC) and sinusoidal pulse width modulation (SPWM) in the inner loop (current control). The simulation results were extracted for dynamic load conditions and the results demonstrated that the THD can be reduced to 0.76% using a combination of SPWM and FLC. Therefore, the proposed system proved to be effective and viable for reducing THD. This system would be highly applicable for renewable energy power generation such as Photovoltaic (PV) and Fuel cell (FC).

scholarly journals Fault Ride through Capability Augmentation of a DFIG-Based Wind Integrated VSC-HVDC System with Non-Superconducting Fault Current Limiter

2019 ◽  
Vol 11 (5) ◽  
pp. 1232 ◽  
Author(s):  
Md Alam ◽  
Mohammad Abido ◽  
Alaa Hussein ◽  
Ibrahim El-Amin
Keyword(s):  
Control Strategy ◽  
Reactive Power ◽  
Current Control ◽  
Control Mode ◽  
Voltage Source ◽  
Fault Current ◽  
Fault Current Limiter ◽  
Hvdc System ◽  
Fault Ride Through ◽  
Current Limiter

This paper proposes a non-superconducting bridge-type fault current limiter (BFCL) as a potential solution to the fault problems of doubly fed induction generator (DFIG) integrated voltage source converter high-voltage DC (VSC-HVDC) transmission systems. As the VSC-HVDC and DFIG systems are vulnerable to AC/DC faults, a BFCL controller is developed to insert sizeable impedance during the inception of system disturbances. In the proposed control scheme, constant capacitor voltage is maintained by the stator VSC (SVSC) controller, while current extraction or injection is achieved by rotor VSC (RVSC) controller. Current control mode-based active and reactive power controllers for an HVDC system are developed. Balanced and different unbalanced faults are applied in the system to show the effectiveness of the proposed BFCL solution. A DFIG wind-based VSC-HVDC system, BFCL, and their controllers are implemented in a real time digital simulator (RTDS). The performance of the proposed BFCL control strategy in DFIG-based VSC-HVDC system is compared with a series dynamic braking resistor (SDBR). Comparative RTDS implementation results show that the proposed BFCL control strategy is very efficient in improving system fault ride through (FRT) capability and outperforms SDBR in all cases considered.

scholarly journals Robust Current Predictive Control-Based Equivalent Input Disturbance Approach for PMSM Drive

Electronics ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1034 ◽  
Author(s):  
Xudong Liu ◽  
Qi Zhang
Keyword(s):  
Predictive Control ◽  
Permanent Magnet Synchronous Motor ◽  
Tracking Error ◽  
Current Control ◽  
Control Technique ◽  
Current Loop ◽  
Input Disturbance ◽  
Current Controller ◽  
Simulation And Experiment ◽  
Equivalent Input Disturbance

The implementation and experimental validation of current control strategy based on predictive control and equivalent input disturbance approach is discussed for permanent magnet synchronous motor (PMSM) control system in the paper. First, to realize the current decoupling control, the deadbeat predictive current control technique is adopted in the current loop of PMSM. Indeed, it is well known that the traditional deadbeat current control cannot completely reject the disturbance and realize the zero error current tracking control. Then, according to the model uncertainties and the parameter variations in the motor, an equivalent input disturbance approach is introduced to estimate the lump disturbance in the system, which will be used in the feed-forward compensation. Thus, a compound current controller is designed, and the proposed algorithm reduces the tracking error caused by the disturbance; the robustness of the drive system is improved effectively. Finally, simulation and experiment are accomplished on the control prototype, and the results show the effectiveness of the proposed current control algorithm.

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