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Recent developments in multilevel inverters have provided impetus for their applications in the medium voltage renewable energy generation processes. This paper proposes an advanced pulse width modulation technique for a modular multilevel cascaded (MMC) inverter based grid integrated solar photovoltaic (PV) system. It offers lower total harmonic distortion (THD) and power losses compared to the existing modulation techniques. This paper shows the design and performance evaluation of the proposed technique using a 3-phase 5-level MMC inverter-based grid connected PV system. The proposed PWM technique offers 12.49% (without filter) and 0.96% (with filter) output line voltage THDs. It also offers 4.64% output current THD, which complies with the IEEE-519 standard for grid integration. Besides THD reduction, it also reduces the switching and conduction power losses of the MMC inverter. Lower losses may help to keep device temperature low, which is essential for power converters used in superconducting magnetic energy storage (SMES) systems. The simulation is performed in MATLAB/Simulink and the proposed technique is experimentally validated with a laboratory test platform.

Nowadays, the use of superconductive magnetic energy storage (SMES) devices in grid integration are highly escalated with the technological amelioration of magnetic components. The power quality and energy conversion efficiency of the power conditioning system of the SMES and renewable energy systems depend on the control algorithms of the voltage source inverter (VSI). However, the traditional control schemes cause inferior response and conversion efficiency. In this paper, an advanced control technique named PI+LLC controller is proposed, which is based on the proportional integral (PI) controller and lead-lag compensator (LLC). The proposed control technique offers significant reduction in the total harmonic distortion (THD), superior dynamic response, smooth response against fault, excellent reference tracking capability of grid current and improved power quality performance at both inverter side and grid side for a 5-level neutral point clamped inverter based grid-tied photovoltaic system. It is expected that, the proposed control scheme can also be used to mitigate the excessive heat of the VSI based SMES system by improving the performance of the power conditioning system. The performance of the proposed control technique is evaluated in MATLAB/Simulink environment to validate the excellent features of the proposed control scheme.

Mitigation of excessive heat due to high frequency switching of voltage source converter (VSC) is always an industrial concern for superconducting magnetic energy storage (SMES) or high temperature superconducting (HTS) material based power conditioning system with grid-tied renewable energy interface. The pulse width modulation (PWM) technique employed for the switching of the VSC has a significant impact on joules heating, switching and conduction power losses, total harmonic distortion (THD) profile of the VSC output, and conversion efficiency in the SMES/HTS based grid-tied power system. In this paper, a modified reference saturated third harmonic injected equal loading PWM technique is proposed for a VSC-based grid-tied photovoltaic (PV) system, which offers lower THD and reduced power conversion losses. The proposed PWM technique employed in the VSC can be used in a PV-based SMES/HTS integrated power system to improve the performance of the power conditioner. To prove the superiority of the proposed PWM technique, a simulation in MATLAB/Simulink was carried out and the simulation results were validated by laboratory tests.

A new three phase multilevel inverter with reduced number of components count is proposed in this paper. This inverter is designed using a single DC source per phase to generate multiple level output voltage which makes it suitable for low and medium voltage applications, including ac-coupled renewables or energy storages. A generalized circuit configuration is shown in this paper following which the number of output voltage level can be increased as per expectation. Although, each element endures the voltage stress equivalent to the input DC voltage, the value of total standing voltage (TSV) is reduced by the utilization of minimized number of components with respect to the number of series connected capacitors. Further, staircase modulation scheme is used to generate the switching signals. Hence, the proposed inverter can be operated at low switching frequency with optimal output current harmonic distortion which decreases switching losses and suppresses power factor falling. In order to validate the theoretical explanations and practical performances of the proposed inverter, the hypothesis is simulated for 9, 13 and 39 output voltage level inverters for three phase with a line voltage total harmonic distortion (THD) of 6.06%, 4.16% and 2.10% respectively in MATLAB/Simulink and a 5-level single phase laboratory prototype is implemented in the laboratory.

The use of control algorithms in inverter topologies is becoming more attractive for integration of wind and photovoltaic (PV) energy with a grid. Among the various inverters, the non-isolated inverter topology has gotten a huge attention for fixing the problem of leakage current issue with other inverters. In this paper, a linear control strategy is offered for the grid connected non-isolated PV inverter. The proposed scheme consists of a proportional resonance (PR) controller with lag compensator (LC). This controller offers lower oscillation in output grid current and better steady state performance for the grid-tied PV inverter systems. The analytical comparison of proposed control scheme and the other control strategies are mentioned in this work. The simulation results indicate the improvements of the performance for the proposed controller in terms of reference tracking ability, total harmonic distortion (THD), and the supplied dc bus voltages of the grid-injected PV inverter systems. This proposed controller can enhance the performance of the PV systems by reducing energy consumption during load change and faulty condition.

Now-a-days, transformer-less grid connected solar photovoltaic (PV) inverters have attracted significant attention due to their special benefits such as higher efficiency, lower cost, and easy set up mechanism. A new transformer-less inverter topology with reduced leakage current and improved performances has been presented in this paper. This inverter circuit has been fabricated with eight semiconductor devices and an LCL filter at the output side. Three switches are used in the common mode voltage (CMV) clamping brunch to enhance inverter efficiency. In the freewheeling brunch, one switch is used so that the leakage current spikes get avoided. In the freewheeling mode common mode voltage is kept constant. While zero voltage state, CMV is clamped to half of the input voltage. The proposed inverter provides only a total of 10.18 mA leakage current. The grid current THD and grid voltage THD are found to be 1.42% and 0.37%, respectively. Unipolar SPWM method has been used to control the power switches. The behavior of the proposed TLPV inverter is verified via simulation analysis performed at MATLAB/Simulink environment.

Renewables such as solar, wind, tide energies are the new route for alternative power sources in spite of fossil fuels or other nonrenewable energies. From the last decade, converting the variable solar dc power to constant ac power has become a challenge. This paper underpins a novel three phase transformer-less grid connected photovoltaic inverter with the control blocks applicable for all types of grid voltage ranges. This novel three-phase inverter topology not only contains very lower reduced leakage current as well as less total harmonic distortion (THD) but also improved power quality. Filter clamping approach has been owned to eliminate extra leakage current through the ground path. Besides unipolar sinusoidal pulse width modulation (SPWM) method has been used to control the power switches. As a result, the common mode voltage has been held to constant, which is also responsible for reducing leakage current to 25.42 mA. The leakage current suppression has been analyzed in details with simulation results. The switches did not affect the efficiency of this inverter so much but reduced the leakage current. Switching losses and conduction losses are very low. The THD of Grid voltage of this proposed topology is recorded 0.94% likewise, grid current THD is measured as 0.42%. To check the performance of this proposed inverter more accurately, input voltage as well as load amount of this inverter have been changed instantly in the middle of simulation. This topology has been implemented and tested via MATLAB/Simulink platform.

Now-a-days, renewable energy has considered a potential source of energy to ensure the sustainable developments. Solar energy plays a vital role not only as a renewable energy source but also an environment friendly energy source. Power electronic inverter is commonly used to interconnect solar photovoltaic (PV) systems to power grids or ac loads. From last decades' industries have been developing solar PV inverters to make it transformer-less compact and lightweight, efficient, and grid friendly. This paper underpins a new single phase TLPV inverter topology, reducing extra leakage current, decreasing total harmonic distortion (THD) and improving power quality. Midpoint clamping method is applied to suppress leakage current. Unipolar sinusoidal pulse width modulation technique with zero dead time have been obtained to control the power switches that also helps to reduce the leakage current plus decreases THD by creating lower ripple on the output voltage. Seven super junction insulated gate bipolar transistors are used as the power switches. 10.28 mA leakage current has been recorded for the proposed inverter. The grid voltage and grid current THD have been recorded 0.42% and 1.62%, respectively. Besides 97.28% European efficiency has been found for this proposed H7 topology. The performance of the proposed inverter has been studied via MATLAB/Simulink simulation.

This paper presents a neutral point clamped (NPC) multilevel inverter (MLI) with an advanced controller for a three-phase grid-tied photovoltaic (PV) system. NPC inverter is the promising candidate among all MLI to mitigate total harmonic distortion (THD) of inverter current for grid-tied PV system. Controller is another crucial part for designing grid-tied power system. In this paper, a PI+HC controller is proposed to improve the control performance of a fifteen-level (15L)-NPC inverter fed grid tied PV system. The proposed controller is based on the linear PI controller which is connected with a feedback of harmonic compensator (HC) to show excellent performance in terms of injected grid current THD, steady state error, sudden load change response, and the capability of handling different fault conditions than existing controllers. The designed controller is simulated in MATLAB/Simulink environment. The simulated results present the excellent performance of the proposed controller.

Nowadays, grid-tied multilevel inverters (MLIs) with closed loop control strategy has carried a great attention due to its superior performance in the superconducting energy system and solar photovoltaic (PV) system. In this paper, an improved PI +LLC (lead-lag compensator control) technique is proposed with a Neutral point clamped (NPC) voltage source MLI fed grid tied PV system. The controller is a proportional integral (PI) controller with the feedback of LLC. It shows excellent performance to minimize total harmonic distortion (THD), steady state error, and almost zero phase shift.

Due to global warming and shortage of fossil fuels, the grid-connected solar photovoltaic (PV) system has gained significant popularity all over the world. The modular multilevel cascaded (MMC) inverter is the natural choice for step-up transformer and line filter less direct medium voltage grid integration of solar PV systems. However, power quality and loss are the important issues while connecting the PV system to the medium voltage grid through MMC inverter. Modulation technique is the key to maintain output power quality, e.g., total harmonic distortion (THD) and to ensure low switching and conduction losses. In this paper, an advanced modulation technique named “triangle saturated common mode pulse width modulation (TSCMPWM)” control is proposed for a 3-phase 5-level MMC inverter-based grid-tied PV system. Compared to traditional modulation techniques, the proposed TSCMPWM control offers the lowest voltage THD as well as lower inverter power losses. Performance of the proposed modulation technique is evaluated in MATLAB/Simulink environment and tested with a reduced scale prototype test platform. Both simulation and experimental results show the effectiveness of the proposed modulation technique.

The use of different control techniques has become very popular for controlling the performance of grid-connected photovoltaic (PV) systems. Although the proportional-integral (PI) control technique is very popular, there are some difficulties such as less stability, slow dynamic response, low reference tracking capability, and lower output power quality in solar PV applications. In this paper, a robust, fast, and dynamic proportional-integral resonance controller with a harmonic and lead compensator (PIR + HC + LC) is proposed to control the current of a 15-level neutral-point-clamped (NPC) multilevel inverter. The proposed controlled is basically a proportional-integral resonance (PIR) controller with the feedback of a harmonic compensator and a lead compensator. The performance of the proposed controller is analyzed in a MATLAB/Simulink environment. The simulation result represents admirable performance in terms of stability, sudden load change response, fault handling capability, reference tracking capability, and total harmonic distortion (THD) than those of the existing controllers. The responses of the inverter and grid outlets under different conditions are also analyzed. The harmonic compensator decreases the lower order harmonics of grid voltage and current, and the lead compensator provides the phase lead. It is expected that the proposed controller is a dynamic aspirant in the grid-connected PV system.