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This paper proposes a decoupled power control algorithm for grid integration of photovoltaic (PV) systems using quasi-Z-source inverter (qZSI). The proposed controller uses model predictive control (MPC) framework to inject the maximum available power harvested from the PV panels to the grid and also to compensate reactive power required by the grid. Thus, a power electronics interface (PEI) is proposed...
With the depletion of fossil fuels and skyrocketing levels of CO2 in the atmosphere, renewable energy sources continue to gain popularity as a long-term sustainable energy source. However, two major limitations exist that prevent widespread adoption: variability of electricity generated and cost of the equipment needed. A grid-tied photovoltaic (PV) / wind hybrid system with battery back-up can help...
Stochastic dynamic behavior of solar energy necessitates the use of robust controllers for photovoltaic (PV) power electronics interfaces. Such robust controller maximizes the energy harvest through continuous operation using a maximum power point tracker (MPPT). A model predictive control MPPT (MPC-MPPT) is proposed in this paper for a quasi-Z-source inverter (qZSI) based grid-connected PV power...
This paper presents the operational control strategy of multi-string photovoltaic (PV) systems in a dc microgrid by using model predictive control (MPC). Due to the intermittent nature of solar energy, battery energy storage system with unify-controlled charger is integrated to the dc microgrid to compensate the fluctuating generated PV power and to regulate the dc-bus voltage. A two-string PV system...
The development of renewable energy power generation is expanding day by day. To harness this energy efficiently and convert it to usable form at higher quality, high efficient and reliable power electronics devices are required. Multilevel inverters are effectively used to produce sinusoidal waveforms at lower filter size. They offer low voltage stress as well as lower harmonic distortion. However,...
High power megawatt (MW) scale drives and power supplies are becoming more prevalent in industrial applications due in part to the development of the Cascaded Multilevel Inverter (CMI) topology. This paper examines the selection of the number of levels for a particular application by using Pareto efficiency analysis to optimize the number of cells with respect to cost, quality, and reliability. This...
Grid-connected energy storage systems have been implemented in ac power systems as uninterruptable power supplies (UPS). Batteries and bi-directional power converters provide electrical power when off-grid and recharge when grid-connected. In this paper, a packed U cells (PUC) seven-level inverter has been selected as the grid-interface due to the lower cost and fewer number of components compared...
This paper presents a grid-connected five-level neutral-point-clamped (NPC)/H-Bridge quasi-impedance source inverter (qZSI) and its control scheme for use in PV applications. The proposed topology is combination of a three-phase qZS network and NPC/H-Bridge inverter that is suitable for high power applications. The proposed inverter transfers dc power into the ac power without dc/dc boost converter...
Variability of the solar energy resources requires highly effective maximum power point tracking (MPPT) to ensure maximum energy harvesting from the photovoltaic (PV) modules. To accomplish this, a MPPT controller typically requires accurate knowledge of the voltage and current from the PV module, and must converge quickly with minimal hunting around the maximum power point (MPP). Conventional MPPT...
Stochastic dynamic behavior of solar energy necessitates the use of robust controllers for photovoltaic (PV) power electronics interfaces to maximize the energy harvest by continuous operation at maximum power point (MPP). This paper proposes a sensorless current model predictive control maximum power point tracking (SC-MPC-MPPT) algorithm. By predicting the future behavior of the power conversion...
This paper presents two new pulse-width modulation (PWM) methods for a high frequency ac-link (HF-link) inverter commutation which uses a form of four-step switching scheme for safe commutation. A HF-link inverter topology enables galvanic isolation and voltage step-up, with a reduced-size transformer, but eliminates the secondary-side rectification so it has less power conversion stages than other...
The battery energy stored quasi-Z-source (BES-qZS) based photovoltaic (PV) power generation system combines advantages of the qZS inverter and the battery energy storage system. However, the second harmonic (2ω) power ripple will degrade the system's performance and affect the system's design. An accurate model to analyze the 2ω ripple is very important. The existing models did not consider the battery,...
The matrix converter solid state transformer (MC-SST), formed from the back-to-back connection of two three-to-single-phase matrix converters, is studied for use in the interconnection of two ac grids. The matrix converter topology provides a light weight and low volume single-stage bidirectional ac-ac power conversion without the need for a dc link. Thus, the lifetime limitations of dc-bus storage...
Single phase rectifiers and inverters are inherently subject to double-line frequency ripple power, at both the ac and dc sides, which has adverse effects on the overall system performance. Normally a bulky capacitor is placed at the dc side of the circuit to prevent this ripple power ripple from reaching the dc source. This approach results in low power density and reliability issues. As a result,...
An improved commutation technique for the ac-ac output converter circuit of a pulse width modulated high frequency link (HF-link) inverter is proposed in this paper. The high frequency link inverter converts a DC input voltage into line frequency AC output voltage using a high-frequency transformer for voltage step-up and galvanic isolation, without an intermediate rectification and dc bus. In this...
The wide band-gap Silicon Carbide (SiC) and gallium nitride (GaN) materials based semiconductor devices have attracted tremendous attentions in modern power electronics applications. They provide much higher switching frequency and higher junction temperature than silicon power devices, thus to significantly decrease the system volume and weight, especially on passive components. In this paper, the...
Wide bandgap (WBG) semiconductors including gallium nitride (GaN) and silicon carbide (SiC) offer significant performance improvement compared with conventional silicon power devices. The quasi-Z-source cascaded multilevel inverter (qZS-CMI) provides many advantages over the conventional CMI while applied in photovoltaic (PV) systems. In this paper, two solutions are proposed and compared to the design...
Active ripple decoupling technique of single-phase inverter is a popular topic to minimize the dc-link capacitance. However, the existing control methods are based on tracking sinusoidal or predetermined voltage waveform of compensation capacitor, where they assume the inverter outputs are pure sinusoidal voltage and current. Therefore, the performance of existing methods degrades when the inverter...
Arcing in photovoltaic (PV) power systems is a significant concern due to the potential for property damage from a PV system fire and personal safety from electrical shock hazard or electrocution if an arc is undetected and left unmitigated. Arc fault detectors are now required by the National Electric Code and Underwriters Laboratories (UL) standard 1699B is currently under development to address...
Arc faults in photovoltaic power systems pose safety concerns ranging from localized damage to the equipment, electric shock hazard for humans, and fire that spreads to buildings and beyond the PV systems. Thus, robust and effective detection of initial arcs before they become sustained arc faults is imperative. However, high frequency noise caused by the switching of DC/DC power optimizers or DC/AC...
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