Grid-Voltage Sensorless Model Predictive Control of Three-Phase PWM Rectifier Under Unbalanced and Distorted Grid Voltages

2020 ◽  
Vol 35 (8) ◽  
pp. 8663-8672 ◽  
Author(s):  
Yongchang Zhang ◽  
Zeting Wang ◽  
Jian Jiao ◽  
Jie Liu
Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2691 ◽  
Author(s):  
Xiaotao Chen ◽  
Weimin Wu ◽  
Ning Gao ◽  
Jiahao Liu ◽  
Henry Shu-Hung Chung ◽  
...  

This paper proposes a novel finite control set model predictive control (FCS-MPC) strategy with merely grid-injected current sensors for an inductance-capacitance-inductance (LCL)-filtered grid-tied inverter, which can obtain a sinusoidal grid-injected current whether three-phase grid voltages are balanced or not. Compared with the conventional FCS-MPC method, four compositions are added in the proposed FCS-MPC algorithm, where the grid voltage observer (GVO) and Luenberger observer are combined together to achieve full status estimations (including grid voltage, capacitor voltage, inverter-side current, and grid-injected current), while the sequence extractor and the reference generator are applied to eliminate the double frequency ripples of the active or reactive power, or the negative sequence component (NSC) of the grid-injected current caused by the unbalanced grid voltage. Simulation model and experimental platform are established to verify the effectiveness of the proposed FCS-MPC strategy, with full status estimations under both balanced and unbalanced grid voltage conditions.


Author(s):  
Mohamed Azab

AbstractFinite control set-model predictive control (FCS-MPC) is employed in this paper to control the operation of a three-phase grid-connected string inverter based on a direct PQ control scheme. The main objective is to achieve high-performance decoupled control of the active and reactive powers injected to the grid from distributed energy resources (DER).The FCS-MPC scheme instantaneously searches for and applies the optimum inverter switching state that can achieve certain goals, such as minimum deviation between reference and actual power; so that both power components (P and Q) are well controlled to their reference values.In addition, an effective method to attenuate undesired cross coupling between the P and Q control loops, which occurs only during transient operation, is investigated. The proposed method is based on the variation of the weight factors of the terms of the FCS-MPC cost function, so a higher weight factor is assigned to the cost function term that is exposed to greater disturbance. Empirical formulae of optimum weight factors as functions of the reference active and reactive power signals are proposed and mathematically derived. The investigated FCS-MPC control scheme is incorporated with the LVRT function to support the grid voltage in fulfilling and accomplishing the up-to-date grid codes. The LVRT algorithm is based on a modification of the references of active and reactive powers as functions of the instantaneous grid voltage such that suitable values of P and Q are injected to the grid during voltage sag.The performance of the elaborated FCS-MPC PQ scheme is studied under various operating scenarios, including steady-state and transient conditions. Results demonstrate the validity and effectiveness of the proposed scheme with regard to the achievement of high-performance operation and quick response of grid-tied inverters during normal and fault modes.


The paper presence a Fuzzy Model Predictive Control (FMPC) for grid tied inverter with multiport DC-DC converter. Three phase grid tied inverter with multiple renewable energy sources are widely used to connect the distributive generating systems to the utility grid. Compare with the conventional control schemes, FMPC scheme is suitable for distributed generation system for its unique advantages likes reliable, fast and more accurate. In this proposed system, different sources having nonlinear parameters and it’s controlled by Fuzzy system. All linear states of three phase grid connected inverters are tested to attain the control objectives. FMPC is proposed to reduce the Total Harmonic Distortion (THD) of the output power. In the proposed system, the inverter control algorithm is developed using some essential vectors. The aim is to monitor the three phase grid current stability and improve the constancy function of the grid-tied inverter during variation of grid voltage. The grid tied converter is designed in two phase standing vector (αβ)model, and the FMPC of grid tied inverter is realized during variation of grid voltage. The simulation results show the superiority of the FMPC in control strategy


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