scholarly journals Dual-Mode Power Operation for Grid-Connected PV Systems with Adaptive DC-link Controller

2021 ◽  
Author(s):  
Mostafa Ahmed ◽  
Ibrahim Harbi ◽  
Ralph Kennel ◽  
Mohamed Abdelrahem
Keyword(s):  
Power Generation ◽  
Voltage Regulation ◽  
Operating Conditions ◽  
Switching Frequency ◽  
Atmospheric Conditions ◽  
Voltage Profile ◽  
Dual Mode ◽  
Power Extraction ◽  
Pv Systems ◽  
Power Operation

AbstractPhotovoltaic (PV) power systems are integrated with high penetration levels into the grid. This in turn encourages several modifications for grid codes to sustain grid stability and resilience. Recently, constant power management and regulation is a very common approach, which is used to limit the PV power production. Thus, this article proposes dual-mode power generation algorithm for grid-connected PV systems. The developed system considers the two-stage PV configuration for implementation, where the dual-mode power generation technique is executed within the DC–DC conversion (boost) stage. Most of the techniques adopted for dual-mode power operation employ the conventional perturb and observe method, which is known with unsatisfactory performance at fast-changing atmospheric conditions. Considering this issue, this study suggests a modified maximum power point tracker for power extraction. Furthermore, a new adaptive DC-link controller is developed to improve the DC-link voltage profile at different operating conditions. The adaptive DC-link controller is compared with the traditional PI controller for voltage regulation. The inverter control is accomplished using finite-set model predictive control with two control objectives, namely reference current tracking and switching frequency minimization. The overall control methodology is evaluated at different atmospheric and operating conditions using MATLAB/Simulink software.

scholarly journals Induction Motor Drives Fed by an NPC Inverter with Unbalanced DC-Link

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1379 ◽  
Author(s):  
Umberto Abronzini ◽  
Ciro Attaianese ◽  
Matilde D’Arpino ◽  
Mauro Di Monaco ◽  
Giuseppe Tomasso
Keyword(s):  
Output Voltage ◽  
Harmonic Distortion ◽  
Voltage Regulation ◽  
Motor Drives ◽  
Operating Conditions ◽  
Switching Frequency ◽  
Voltage Level ◽  
Voltage Quality ◽  
Vector Modulation

Neutral Point Clamped (NPC) converters with n levels are traditionally controlled in such a way that the DC-link capacitors operate at 1/( n - 1) of the total DC-link voltage level. The voltage level across the DC-link capacitors has to be properly regulated by the capacitor unbalance control to contain the harmonic distortion of the converter output voltages. State-of-the-art modulation techniques address the problem of the DC-link voltage regulation for NPC inverters. However, they highly show reduced performance when unbalanced DC-link voltages are considered. In this paper, a novel Space Vector Modulation (SVM) is proposed for NPC converters with an unbalanced DC-link. At every modulation interval, the technique defines the optimal switching pattern by considering the actual unbalanced DC-link conditions. The proposed modulation allows improving the harmonic content of the NPC converter output voltage with respect to a traditional ML-SVM, when the same operating conditions are considered. As an extension, the proposed modulation technique will guarantee the same output voltage quality of a traditional ML-SVM with unbalanced DC-link, while improving the conversion efficiency thanks to a reduction of switching frequency.

scholarly journals Control-Oriented Model of Photovoltaic Systems Based on a Dual Active Bridge Converter

2021 ◽  
Vol 13 (14) ◽  
pp. 7689
Author(s):  
Diego Alejandro Herrera-Jaramillo ◽  
Elkin Edilberto Henao-Bravo ◽  
Daniel González González Montoya ◽  
Carlos Andrés Ramos-Paja ◽  
Andrés Julián Saavedra-Montes
Keyword(s):  
High Voltage ◽  
High Efficiency ◽  
Voltage Regulation ◽  
Pv System ◽  
Power Extraction ◽  
Pv Systems ◽  
Dual Active Bridge ◽  
Pv Module ◽  
Proposed Model ◽  
Voltage Conversion

Solar energy is a source of sustainable energy and its optimal use depends on the efficiency and reliability of PV systems. Dual active bridge converters are a solution to interface PV modules with the grid or high voltage requirement applications due to the high voltage-conversion-ratio and high efficiency provided by such a converter. The three main contributions of this work are: an extensive mathematical model of a DAB converter connected to a PV module including protection diodes, which is intended to design non-linear controllers, an explicit linearized version of the model, which is oriented to design traditional control systems; and a detailed and replicable application example of the model focused on maximizing the power extraction from a PV system. The modeling approach starts with the differential equations of the PV system; however, only the fundamental and average components of each signal is used to represent it. The control-oriented model is validated using a detailed circuital simulation. First, through the comparison of frequency and time diagrams of the proposed model and a detailed one; and then, through the simulation of the PV system in a realistic application case. PV voltage regulation and maximum power extraction are confirmed in simulation results.

scholarly journals Wide Input Voltage Range Operation of the Series Resonant DC-DC Converter with Bridgeless Boost Rectifier

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4220
Author(s):  
Abualkasim Bakeer ◽  
Andrii Chub ◽  
Dmitri Vinnikov ◽  
Argo Rosin
Keyword(s):  
Input Voltage ◽  
Voltage Regulation ◽  
Operating Conditions ◽  
Reverse Direction ◽  
Switching Frequency ◽  
Half Cycle ◽  
Wide Range ◽  
Series Resonant ◽  
Boost Rectifier ◽  
Abnormal Operating Conditions

The series resonant DC-DC converter (SRC) can regulate the input voltage in a wide range at a fixed switching frequency. In this work, the bridgeless rectifier, which is utilized intensively in the applications of the power factor correction, has been integrated into the SRC as a voltage step-up cell at the output-side of the SRC. It is shown that the conventional overlapping pulse-width modulation (PWM) of the two metal oxide semiconductor field-effect transistors MOSFETs in this rectification cell limits the input voltage regulation range of the converter due to excessive power losses in abnormal operating conditions. The abnormal operating conditions occur when the instantaneous voltage across the resonant capacitor is larger than the secondary voltage of the isolation transformer. This happens at high values of the DC voltage gain, i.e., low input voltages and high currents, which causes the resonant current to flow in the reverse direction in the same half-cycle through a parasitic path formed by overlapping PWM of the rectifier MOSFETs. The abnormal operation results in additional conduction loss in the converter as the MOSFETs of the bridgeless boost rectifier turn on at high current at the beginning of each half of the switching period. Accordingly, the overall efficiency of the converter significantly deteriorates. This paper proposes the hybrid PWM aiming to improve the efficiency of the SRC with a bridgeless boost rectifier in a wide input voltage regulation range. The converter swaps between the overlapping and the proposed short-pulse PWM schemes to drive the MOSFETs in the bridgeless boost rectifier. The transition between the two PWM schemes is defined according to the boundary condition that relies upon the operating point of the converter power and the input voltage. The proposed hybrid PWM scheme is analyzed and compared to the overlapping PWM at different levels of the input voltage and the load power. A 300 W prototype was studied in the laboratory to show the feasibility of the proposed hybrid PWM scheme with the closed-loop control system to switch between the two PWM schemes.

scholarly journals Evaluation of the Effective Active Power Reserve for Fast Frequency Response of PV with BESS Inverters Considering Reactive Power Control

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3437 ◽  
Author(s):  
Dario Garozzo ◽  
Giuseppe Marco Tina
Keyword(s):  
Power Control ◽  
Frequency Response ◽  
Reactive Power ◽  
Voltage Regulation ◽  
Active Power ◽  
Operating Conditions ◽  
Frequency Regulation ◽  
Reactive Power Control ◽  
Pv Systems ◽  
The Impact

The increasing presence of distributed generation (DG) in the electrical grid determines new challenges in grid operations, especially in terms of voltage and frequency regulation. Recently, several grid codes have required photovoltaic (PV) inverters to control their reactive power output in order to provide voltage regulation services, and the allocation of a certain amount of active power reserve for fast frequency response (FFR) service during under-frequency contingencies is needed. This requirement involves a significant waste of energy for PV systems, due to the necessity to constantly operate in de-loaded mode, under normal operating conditions. In addition, the variability of the irradiance can affect the correct amount of active power reserve that the system can provide in the moments after an under-frequency occurrence. The increasing number of battery energy storage systems (BESSs), coupled to PV systems, can be used to provide a worthy contribution to this frequency regulation service. The aim of this paper is to analyze the efficiency of active power reserve provided by a BESS connected to the DC bus of a non-ideal grid-connected PV inverter, taking into account the impact of reactive power control. For this purpose, the contribution of BESSs to frequency regulation is discussed and, starting from an existing model of real inverter, an analytical formulation for active power reserve evaluation is presented. Results concerning the impact of reactive power control are also given. Finally, the possibility for a low voltage (LV) grid with aggregated PV systems and BESSs to contribute to grid active power reserve is considered. Different voltage control strategies are compared, defining a helpful new parameter.

Waste to Energy Conversion and Sustainable Recovery of Nutrients from Pee Power - Recent Advancements in Urine-Fed MFCs

2020 ◽  
Vol 17 (7) ◽  
pp. 768-779
Author(s):  
Natarajan Narayanan ◽  
Vasudevan Mangottiri ◽  
Kiruba Narayanan
Keyword(s):  
Power Generation ◽  
Microbial Fuel Cells ◽  
Alternative Energy ◽  
Material Selection ◽  
Waste Product ◽  
Resource Recovery ◽  
Operating Conditions ◽  
Waste To Energy ◽  
Animal Origin ◽  
Human Beings

Microbial Fuel Cells (MFCs) offer a sustainable solution for alternative energy production by employing microorganisms as catalysts for direct conversion of chemical energy of feedstock into electricity. Electricity from urine (urine-tricity) using MFCs is a promising cost-effective technology capable of serving multipurpose benefits - generation of electricity, waste alleviation, resource recovery and disinfection. As an abundant waste product from human and animal origin with high nutritional values, urine is considered to be a potential source for extraction of alternative energy in the coming days. However, developments to improve power generation from urine-fed MFCs at reasonable scales still face many challenges such as non-availability of sustainable materials, cathodic limitations, and low power density. The aim of this paper was to critically evaluate the state-of-the-art research and developments in urine-fed MFCs over the past decade (2008-2018) in terms of their construction (material selection and configuration), modes of operation (batch, continuous, cascade, etc.) and performance (power generation, nutrient recovery and waste treatment). This review identifies the preference for sources of urine for MFC application from human beings, cows and elephants. Among these, human urine-fed MFCs offer a variety of applications to practice in the real-world scenario. One key observation is that, effective disinfection can be achieved by optimizing the operating conditions and MFC configurations without compromising on performance. In essence, this review demarcates the scope of enhancing the reuse potential of urine for renewable energy generation and simultaneously achieving resource recovery.

scholarly journals A New MPPT Algorithm for Photovoltaic Power Generation under Uniform and Partial Shading Conditions

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 483
Author(s):  
Novie Ayub Windarko ◽  
Muhammad Nizar Habibi ◽  
Bambang Sumantri ◽  
Eka Prasetyono ◽  
Moh. Zaenal Efendi ◽  
...  
Keyword(s):  
Power Generation ◽  
Duty Cycle ◽  
Operating Conditions ◽  
Maximum Power ◽  
Maximum Power Point ◽  
Partial Shading ◽  
Photovoltaic Panel ◽  
Maximum Power Point Tracker ◽  
Photovoltaic Power ◽  
Power Point

During its operation, a photovoltaic system may encounter many practical issues such as receiving uniform or non-uniform irradiance caused mainly by partial shading. Under uniform irradiance a photovoltaic panel has a single maximum power point. Conversely under non-uniform irradiance, a photovoltaic panel has several local maximum power points and a single global maximum power point. To maximize energy production, a maximum power point tracker algorithm is commonly implemented to achieve the maximum power operating point of the photovoltaic panel. However, the performance of the algorithm will depend on operating conditions such as variation in irradiance. Presently, most of existing maximum power point tracker algorithms work only in a single condition: either uniform or non-uniform irradiance. This paper proposes a new maximum power point tracker algorithm for photovoltaic power generation that is designed to work under uniform and partial shading irradiance conditions. Additionally, the proposed maximum power point tracker algorithm aims to provide: (1) a simple math algorithm to reduce computational load, (2) fast tracking by evaluating progress for every single executed duty cycle, (3) without random steps to prevent jumping duty cycle, and (4) smooth variable steps to increase accuracy. The performances of the proposed algorithm are evaluated by three conditions of uniform and partial shading irradiance where a targeted maximum power point is located: (1) far from, (2) near, and (3) laid between initial positions of particles. The simulation shows that the proposed algorithm successfully tracks the maximum power point by resulting in similar power values in those three conditions. The proposed algorithm could handle the partial shading condition by avoiding the local maxima power point and finding the global maxima power point. Comparisons of the proposed algorithm and other well-known algorithms such as differential evolution, firefly, particle swarm optimization, and grey wolf optimization are provided to show the superiority of the proposed algorithm. The results show the proposed algorithm has better performance by providing faster tracking, faster settling time, higher accuracy, minimum oscillation and jumping duty cycle, and higher energy harvesting.

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