This paper presents an improved sequential model predictive control (MPC) method for single phase photovoltaic (PV) applications. The T-type H-bridge five-level topology is selected in this paper. The proposed method achieves constant switching frequency operation of the inverter, which is advantageous over the variable switching frequency MPC methods. The proposed fixed switching frequency MPC (FSF-MPC) method eliminates the weighting factors, which represent critical element in applying classical MPC methods. Moreover, the proposed FSF-MPC method achieves low dv/dt values through using optimized switching sequences to evaluate the cost function. The simulation results of the proposed FSF-MPC method are provided and compared with variable switching frequency MPC method. The results show the fast tracking in both controllers. Whereas, fixed switching frequency and weighting factorless operation are obtained using the proposed FSF-MPC method. Additionally, lower total harmonic distortion (THD) in the output voltage is obtained using the proposed FSF-MPC method compared to classical MPC method.

Battery energy storage systems (BESSs) have be-come integral parts in photovoltaic (PV) energy systems due to their fluctuated nature. The most common solutions in the literature for hybrid PV-battery systems are based on two-stage power converter solutions with separate power converters. However, these solutions increase the cost of the system and the number of required devices. Additionally, leakage currents represent critical issue for safe and reliable operation of PV systems. This paper presents a three-port configuration for hybrid PV-battery grid-connected systems. The proposed configuration includes a common ground connection between the PV side and grid side, which results in the elimination of leakage current components. Moreover, a finite control set model predictive control (FCS-MPC) is presented in this paper for controlling the proposed three-port configuration. The proposed controller achieves the control of multiple objectives simultaneously in addition to having fast dynamic response. Simulation results of the proposed configuration and control method are provided in this paper. The results show the effectiveness of the proposed configuration for hybrid PV-battery systems.

This paper presents a new common grounded (CG) multilevel boost inverter (MI) topology for single-phase grid-tied photovoltaic (PV) applications. The proposed topology has the capability to fully eliminate the leakage currents in PV systems due to the using of the CG connection. Additionally, the proposed topology benefits the high boosting factor capability of the low PV voltage. The proposed topology represents a single stage power conversion system with reduced power components compared to the traditional two-stage PV power conversion systems. In addition, model predictive controller (MPC) is proposed in this paper to control the proposed topology. The proposed controller can control multiple objectives simultaneously without using cascaded controllers. The simulation results with the different case studies are provided. The results confirm the superiority of the proposed CG boost MI topology and the proposed MPC method. Furthermore, fast tracking of the grid active and reactive power demands is achieved using the proposed MPC method.

In this paper, a space Vector modulation scheme (SVMS) to enhance the performance of the single-stage three-phase grid-tied SEPIC-based differential inverter is presented. Compared to the traditional modulation schemes, the proposed modulation scheme offers a significant reduction in the peaks of output voltages and input currents of the utilized SEPIC modules at the same voltage gain. Moreover, the peak voltages of the utilized capacitors in SEPIC converters are reduced. Therefore, the voltage stresses, conduction losses, and switching losses have been decreased, and the system efficiency has been increased in accordance. The proposed SVMS is implemented by employing a simple modification to the traditional continuous modulation scheme (CMS) of differential inverters, which keeps the smooth operation of the grid-current control at the inverter side and verifies low execution time. Moreover, a detailed comparison between the proposed modulation scheme and traditional CMS at different power ratings is introduced. The performance of the proposed SVMS is evaluated using the PSIM environment to validate the theoretical features added to the grid-current control and the SEPIC-based differential inverter.

Transformerless photovoltaic (PV) inverter topologies have proven superior performance over transformer-based inverter topologies. However, they face challenges due to their high leakage currents and voltage step-up requirements. There-fore, modified topologies and/or modulation techniques are essential to limit the current leakages to standard limits. The doubly grounded (DG) inverter topologies represent efficient solutions for totally limiting the leakage currents. This paper presents a finite control set (FCS) model predictive controller (MPC) method for DG step-up five-level PV inverter topology. The proposed FCS-MPC method can control the injected grid currents and multiple capacitors voltages simultaneously with high power quality output. The modelling and design of the step-up inverter topology and the FCS-MPC method are given in the paper. Simulation results with step-up DG five-level PV inverter topology are performed to validate the proposed FCS-MPC method. Moreover, the proposed FCS-MPC method has been validated using simulation results at the various operating conditions of PV inverters.

Fault tolerant (FT) operation in photovoltaic (PV) inverters is gaining increased attention in order to improve system availability. Conventional string PV inverters lack the ability to eliminate the leakage currents of the system during fault modes of operation. Therefore, traditional PV inverters are modified through modulations and structures to tolerate such faults. However, proper operation and control of FT-PV-inverters remain challenging, particularly on the better utilization of the extra added components. This paper proposes a new modulation method for eliminating the PV inverter leakage current in normal and faulty modes of operations. The sinusoidal based pulse width modulation (PWM) scheme is modified for implementing the new proposed modulation. In addition, the proposed PWM is capable of preserving full rating and energy efficiency operation of the inverter with leakage current elimination in both the normal and faulty operating modes. The proposed inverter and modulation method are implemented and tested at various conditions. The results confirm the superiority and leakage current elimination capability of the new proposed PWM method.