Renewable Energy Power Generation System Research Articles

Design of low‐stress ultrahigh‐gain dc–dc converter with coupled inductor

AbstractThe dc–dc converter plays a vital role in renewable energy power generation systems. To enhance the boost range and supply stable output voltage for the power grid, This paper propose an improved low‐stress ultrahigh‐gain dc–dc converter. First, a voltage multiplier cell is designed stemming from a three‐winding coupled inductor and a switched capacitor (SC), which can obtain ultrahigh voltage gain. In the improved voltage multiplier cell, the number of semiconductor devices is reduced, resulting in a decrease in capacitor voltage stress. Moreover, a passive clamp circuit uses the new SC, which can suppress oscillation peak voltage and absorb the leakage energy of the coupled winding. Furthermore, we deduce the operating mode of the proposed converter . Compared with other advanced topologies, the proposed topology outperforms boosting capacity, component stress, and efficiency. To stabilize the output voltage, the converter is closed‐loop controlled. Finally, experiments on the 180 W prototype have demonstrated the reliability and effectiveness of the proposed topology.

Push-pull forward LLC resonant converter for low input voltage applications

A push-pull forward LLC resonant converter suitable for renewable energy power generation systems is proposed in this paper. The converter introduces the LLC resonant tank into the traditional push-pull forward converter and adopts pulse frequency modulation (PFM) control, which solves the problem of voltage spike of switches of the conventional push-pull converter, realizes the zero-voltage switching (ZVS) of the switches and has high conversion efficiency. In addition, the rectifier part of the structure adopts voltage doubling rectifier technology, which is beneficial to reduce the turn ratio and optimize the leakage inductance of the transformer. In this paper, the working principle of the converter is described in detail, and its gain characteristics and soft switching conditions are analyzed. Finally, an experimental prototype of 1 kW is built, and the output voltage of 380 V is achieved when the rated input voltage is 48–72 V, and its efficiency is up to 96.1 %.

Energy scheduling method for island micro-grid system based on prediction model

Abstract Renewable energy, due to its characteristics such as volatility and intermittency, brings difficulties to the energy scheduling of renewable energy power generation systems. The main way of island power generation is to use renewable energy power generation. This chapter proposes a hierarchical energy scheduling method based on the prediction model through the research on the energy scheduling method of the island microgrid system to realize the energy optimization between the microgrid sub-systems, to achieve the maximum consumption of renewable energy for power supply, and to reduce the power supply cost and improve user satisfaction. The effectiveness of this method in improving the energy supply-demand balance of the microgrid sub-systems is verified through experiments.

A Series Impedance Reshaping Control Method Considering PLL Dynamics for Grid-Connected Inverters Under Weak Grid Conditions

Grid-connected inverters are the key part in renewable energy power generation systems. Usually, phase-locked loop (PLL) is adopted in grid-connected inverters to achieve synchronization. However, prior-art works have revealed that the negative resistance behavior in the low-frequency band caused by PLLs may lead to system instability under weak grids. In this paper, first, a comprehensive small-signal output impedance modeling of the LCL-filtered single-phase grid-connected inverter is derived for stability analysis, where the digital control delays and PLL dynamics have been taken into account. Then, a simple but effective virtual series based impedance reshaping method is proposed. With that, the inverter system can operate stably even under a very weak grid (e.g., short-circuit ratio (SCR) is as low as 1.2). Compared with the traditional grid impedance compensation by virtually increasing grid resistance or reducing the grid inductance, the proposed method does not require grid impedance estimation and is robust against system parameter variations. Thus, its feasibility is improved. Finally, experimental tests are carried out on a single-phase 5-kW prototype, validating the effectiveness of the proposed scheme.

A smart parametrisation for robust adaptive PI controller applied on renewable energy power generation systems under weak and uttermost weak grid conditions

The increasing penetration of renewable energy systems into the global energy matrix is a necessity for sustainable development. The benefits impact the well-being of humanity and the environment directly. However, these power generation systems demand reliable controllers to regulate the current injection into the electrical grid. Therefore, this paper presents a smart parametrisation for a robust adaptive proportional integral controller applied to grid-injected current control of a voltage inverter source with an LCL filter. Controller parameter optimisation and the initialisation of their gains are performed using the particle swarm optimisation algorithm. Three cost functions are assessed on controller parametrisation, considering the current tracking error minimisation and control action limitations: integral of absolute error (IAE) + integral of absolute control action (IAU), integral of square error (ISE) + IAU, and integral of the time-weighted absolute error (ITAE) + IAU. A framework for performance analysis and an in-depth discussion are presented, providing a systematic decision-support methodology for controller configuration. The function determined as the best one is implemented experimentally and compared with a designer’s experience-based robust adaptive proportional integral controller using a hardware-in-the-loop test bench, where the improvements in controller performance are corroborated, contributing to the enhancement of energy quality in renewable energy systems. In addition, the controller’s robustness is evaluated on a weak grid and an uttermost weak grid, where it presents high robustness and global stability.

Simulation of Small-Scale Solar Power Generation System in The Central Java Region: A Case Study of the Cilacap Area

The limitations of conventional non-renewable energy resources raise concerns about sustainability and energy supply security in the future. One of the worrying factors is the carbon dioxide emissions that can affect living organisms' health. Renewable energy sources, such as solar, wind, and hydropower, emerge as solutions capable of minimizing environmental impacts and reducing dependence on limited resources. Therefore, this research will simulate and design a small-scale renewable energy power generation system, particularly solar energy, in the Cilacap region, Central Java. The main components involved in this research include PV arrays, IGBT diodes, and universal bridges, supported by supporting elements such as displays, scopes, resistors, capacitors, inductors, and bus selectors. The technical data used as input are specific to the area. The simulation results show that the direct power generated by one modelled PV array is 221.7 W per hour. This research contributes to optimising small-scale solar power generation systems in the designated area, considering relevant components and parameters to enhance efficiency and sustainability.

A Novel Non-Isolated Cubic DC-DC Converter with High Voltage Gain for Renewable Energy Power Generation System

A Novel Non-Isolated Cubic DC-DC Converter with High Voltage Gain for Renewable Energy Power Generation System

An optimal initialisation for robust model reference adaptive PI controller for grid-tied power systems under unbalanced grid conditions

This paper presents an Optimal Robust Model Reference Adaptive Proportional–Integral controller for grid-tied power systems, which is automatically parametrised using a Genetic Algorithm. The task of choosing the adaptation rate and the controller’s initial gains set is now performed in a computational and automatic way, saving design time and ensuring satisfactory transient regimes.The use of a Genetic Algorithm for complete parametrisation of robust adaptive controllers applied to renewable energy power generation systems with LCL filter is first here explored. Five cost functions are considered in the optimisation process. A comparison of simulation results applying the optimised controller in a grid-tied Voltage Source Inverter with LCL filter points out the benefits and drawbacks of using each cost function. A framework for performance analysis and an in-depth discussion are provided. The function determined as the best one, which is integral of absolute error, is used in the controller implemented experimentally, ensuring suitable tracking of grid current references and rejection of grid voltage harmonics, even under unbalanced grid voltage conditions. An experimental comparison in a three-phase 6.75 kW power converter with the non-optimised controller is also provided, where the optimised controller obtains a reduction in the overshoot in all transient regimes and smaller tracking error, resulting in a reduction in the mean error of 14.31% and 60.30% in α and β coordinates, respectively. In addition, the optimised controller reduces total harmonic content, improving energy quality. This parametrisation procedure can be immediately extended to the control of any other power converter systems.

Optimal energy management strategy for distributed renewable energy power generation system based on “three-flow” theory

Aiming at the off-grid application of distributed renewable energy, this study proposes a combined hydrogen, heating and power system based on solar energy, which mainly includes alkaline water electrolysis, metal-hydride hydrogen storage and proton exchange membrane fuel cells. To achieve the best combination of electricity, heat, and hydrogen, four energy management strategies based on mass, energy, and information flow are proposed. Taking an ecological community in Ningbo as the application scenario, the system performance under four control strategies in typical summer and winter days is studied, and the best control strategies in summer and winter are given, respectively. Electricity-led and high-led strategies are recommended for summer and winter, and both strategies can achieve a real-time supply of electric power, heating power, and hydrogen. After a day of operation, the two strategies have surpluses of 0 and 221.5 kW h of electricity, 5706 and 102.16 MJ of heat, and 57 and 17.82 kg of hydrogen, respectively.

A Novel Modulation Strategy for Split-Inductor Active NPC Inverter With Loss Distribution Balancing and Thermal Stress Reduction

Neutral point clamped inverter (NPC) features low harmonics, high efficiency, and low voltage stress, et al. NPC is widely applied in renewable energy power generation systems, such as wind turbine power and photovoltaic. However, due to unbalanced power losses, NPC suffers inherent thermal unbalance among inner and outer power switches. A split-inductor active neutral point clamped inverter (SI-ANPC) was initially proposed to improve the operating reliability, providing the structural basis for balanced loss distributions. With this purpose, a novel modulation strategy with balanced loss distribution for SI-ANPC is proposed in this paper. The modulation strategy is analyzed under the unity and non-unity power factors. In specially, two redundant zero-state paths are fully used. Under the unity power factor, the power switches operate at the switching frequency or maintain the conduction state complementarily. Considering the phase angle in the non-unity power factor situation, the working patterns of power switches are rearranged to reduce the loss difference. The thermal stress is decreased on both occasions. Finally, loss calculation results, experimental waveforms, and thermal images of the inner and outer switches are presented to confirm the effectiveness of the proposed modulation strategy.

Energy Storage Optimization of Wind Solar Hybrid Power Generation System Based on Improved Grasshopper Algorithm

During the heating period, the solid thermal storage electric boiler is added to use the waste electricity for local heating, and the corresponding energy storage optimization model of wind solar hybrid power generation system is constructed with the maximum waste electricity contotalityption and the minimum power purchase cost as the objective function, and the contotalityption and waste electricity constraint, system power balance constraint, electric boiler power constraint, heat storage constraint, and regulation times constraint as constraint conditions. Improved moth algorithm is constructed to solve the optimization model, and a Pareto solution set with both economy and reliability is obtained. Optimal compromise solution is screened out from the Pareto solution set, and optimal configuration capacity of the thermal storage electric boiler and annual amount of electricity discarded in the system can be obtained. Thus, the power rejection in the system can be reduced, promoting widespread use of independent renewable energy power generation systems.

Thirteen-Level Switching Capacitor Inverter with Six Times Boost and Self-Balancing Capability

A thirteen-level inverter based on switching capacitor is proposed in order to improve the boost capacity and output power quality of inverter in renewable energy power generation system. The proposed topology is composed of one DC input power supply, three capacitors and 14 switching devices, and achieves thirteen-level output with six times voltage boost. It has smaller volume, lower cost and output harmonic content. Moreover, it can realize inverter without H bridge and reduce the voltage stress of switching tube. In addition, the proposed inverter can achieve self-balancing capacitor voltage without any auxiliary method, simplifying the complexity of control. The superiority of the proposed topology is verified by comparing with other traditional multilevel inverters. The simulation and experimental verification on the simulation and prototype platform show that the inverter has good performance in both steady and dynamic conditions.

Online Digital Implementation of Wide Voltage Range RMS-Current-Optimized Control With Voltage Balancing Capability for DAB Converter

The dual active bridge (DAB) converter is widely used in renewable energy power generation systems with wide input voltage characteristics. An inappropriate duty cycle will lead to a larger inductor RMS current and low efficiency. In this paper, an efficiency-oriented optimized triple-phase-shift (OTPS) scheme is proposed for the dual active bridge (DAB) converter that can reduce the inductor root-mean-square (RMS) current for a wide input voltage and realize zero voltage switching (ZVS). The ZVS condition contains the direction and amplitude of the inductor current to make the ZVS area more accurate. In addition, the OTPS scheme also has the capability of voltage balancing without additional voltage equalizers under unbalanced load. The influence of deadtime on voltage balance is analyzed and a voltage balancing scheme with compensation of the duty cycle is proposed. To reduce resource occupation and operation time, an on-line implementation scheme of variable parameter control (VPC) based on field programable gate array (FPGA) is proposed. Without a look-up table, the sum of the operation time of the control module and modulation module is only 0.66 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> s, and the required memory bits are only 459k. Both operation time and memory bits are reduced by more than 90% compared to existing literature. Finally, the whole proposed process is verified by the experimental results.

Performance assessment of hydrogen-based commercial hybrid renewable energy power generation system

The world is transitioning toward hybrid renewable energy systems in order to cope with increased power demand. The aim of this research article is to assess various hydrogen-based hybrid renewable energy systems (HRES) based on their performance, which is used commercially. A total of nineteen projects were selected at random across different regions and evaluated based on the analytic hierarchy process (AHP). In order to compare, five criteria are selected viz. 1. Plant Capacity, 2. Electrolyzer Capacity, 3. Utilization of Energy Produced, 4. Energy Sources Involved, 5. Type of Hydrogen Storage Technology Used. Plant Capacity and Energy sources involved are the criteria given more weightage. Using AHP multi-criteria decision-making was possible and all the projects are ranked accordingly based on performance parameters. SCHATZ Solar Demonstration Project, USA, 1989 was given a priority of 0.8% with a rank of 16 despite being the oldest project. Wherein, Foshan Hydrogen City Project, China, 2018 was assigned a priority of 23.2% and ranked 1st. Projects were prioritized and ranked with a consistency ratio (CR) of 28.9% in AHP.

Retracted: Modeling and Control of Wind Speed in Renewable Energy Power Generation and Wind Power Generation Systems

Retracted: Modeling and Control of Wind Speed in Renewable Energy Power Generation and Wind Power Generation Systems

Temperature Dependence of the Alkaline Oxygen Evolution Reaction Catalyzed By Amorphous/Crystalline Ni-Co Oxides

As the installation of renewable energy power generation systems such as solar and wind power increases, efficient energy storage devices are needed to overcome the problem of fluctuations in the availability of electrical energy. In particular, water splitting by electrolysis to produce storable hydrogen and oxygen appears to be one of the most promising approaches for large-scale energy storage. However, the efficiency of water electrolysis is greatly restricted due to the high overpotential required for the anodic oxygen evolution reaction (OER). Therefore, effective catalysts are needed to accelerate the reaction, reduce overvoltage, and increase energy conversion efficiency. Among various OER catalysts, nickel-cobalt oxides have received enormous attention due to their low cost and high OER activity in alkaline electrolyte. A better understanding of the OER kinetics is essential for accurate activity/durability predictions and the development of next generation OER catalysts. In this work, we synthesized a series of Ni-Co oxides with tunable amorphous/crystalline surface structures, with particular emphasis on the temperature dependence of the OER catalysis, as a way to elucidate the catalytic reactions, from both experimental and theoretical perspectives.The Ni-Co oxide was synthesized by the flame oxide-synthesis method.1 The as-prepared sample was treated in an oxidizing atmosphere (20% O2/N2) at elevated temperatures (from room temperature to 300 °C) without changing the Ni-Co-O atomic composition. Based on the measured composition and treatment temperature, the obtained three catalysts were denoted as Ni0.8Co0.2O-RT, Ni0.8Co0.2O-100, and Ni0.8Co0.2O-300. The OER activities were evaluated in 1 M KOH at 20 to 80 oC by use of the rotating disk electrode (RDE) technique.2 It was found that the increase in O2-treatment temperature led to increased structural order or crystallization of the oxide phase, i.e., crystallinity Ni0.8Co0.2O-RT < Ni0.8Co0.2O-100 < Ni0.8Co0.2O-300, as confirmed by XRD measurement. Figure 1a showed that the Ni-Co oxide materials presenting an amorphous or poorly crystalline oxide phase showed higher activity than their crystalline counterparts, which was correlated with a negative shift in the oxyhydroxide formation peak potential (inset of Figure 1a). The OER activation energy, extracted from temperature dependence of OER currents, also decreased with decreasing the crystalline oxide phases (Figure 1b). Thus, efficient OER was demonstrated to be associated with facilitated formation of oxyhydroxide species during electrochemical anodization. We proposed, based on density functional theory calculations, that the amorphous or disordered structure of the oxide top surface layers renders the surface geometry energetically favorable for the crucial step O + OH → OOH, which significantly accelerates the OER activity.This work was partially supported by funds for the JSPS KAKENHI (20H02839), and the project from the New Energy and Industrial Technology Development Organization (NEDO) of Japan.[1] K. Kakinuma, M. Uchida, T. Kamino, H. Uchida, and M. Watanabe, Electrochim. Acta, 56, 2881 (2011).[2] G. Shi, T. Tano, D. A. Tryk, A. Iiyama, M. Uchida, and K. Kakinuma, ACS Catal., 11 , 5222 (2021). Figure 1

A Modified Interleaved Capacitor Clamped DC–DC Converter With Non-Resonant Soft Switching

Since the solar panels and fuel cells have low output voltage, which need to be converted to the 400 V or higher dc bus voltage in the renewable energy power generation systems, where, the high gain dc–dc converter plays a key role. Furthermore, with the requirement of the converter in low cost and high efficiency, the soft-switching interleaved boost-type converters based on switched-capacitor and voltage multiplier cell as the high gain dc–dc converters have been widely applied. However, the above-mentioned soft-switching interleaved boost-type converters in literature have resonant spikes on the switches or there are coupled inductors, which will cause the high cost due to the large stresses of the switches or low efficiency due to the high core losses of the coupled inductors. To solve the above-mentioned problems, a modified interleaved capacitor clamped (MICC) dc–dc converter with non-resonant soft-switching (NRSS) is proposed, in which only an auxiliary inductor operating in discontinuous conduction mode with few μH is used to achieve the zero-current-switching for all switches and diodes. Furthermore, the operating principle of the proposed converter is given, the interleaved boost structure is used as the front stage of the proposed converter to reduce the input current ripple and lighten the current stress on all switches and magnetic components, the MICC structure with NRSS as the output stage is proposed as a voltage multiplier module to achieve the high voltage gain. Then, the circuit parameter design for this converter is presented. Finally, a 400 W experimental prototype is built to verify the correctness and the effectiveness of the proposed topology.

Modeling and Control of Wind Speed in Renewable Energy Power Generation and Wind Power Generation Systems

Wind energy is one of the most used clean energy sources in renewable energy, and its renewable and sustainable nature is one of the reasons why it is used for power generation. In the current environment where all countries in the world are facing energy problems, research on wind power generation systems is also increasing. This article aims to study the problem of modeling and controlling wind speed in the wind power generation system of renewable energy power generation. To this end, this article proposes a modeling method for wind power generation systems, which can be used to study the momentum problems in wind power generation and the mechanical torque of the generator. And at the end of the article, related experiments and analysis are designed to explore and compare its operating cost, speed, and wind wheel speed. The experimental results in this paper show that through effective modeling and control of its wind speed, the economic risks in the actual wind power generation system can be controlled, with a maximum reduction of 24%, and the actual operating cost is also reduced by 8.66%, so wind power has high practical value.

Research on optimal matching of renewable energy power generation system and ship power system

In order to realize the comprehensive utilization of multiple energy sources in renewable energy ships and improve the utilization rate of renewable energy and system economy, this paper studies the matching and optimization of renewable energy power generation system and ship power system. Firstly, the structure of renewable energy ship power system is introduced. Considering the natural conditions and the actual situation of the ship for the first time, the wind power generation, photovoltaic power generation and energy storage devices are configured in the ship power system. The objective function including system annual average cost and system reliability index is established. The constraint conditions are determined, and the system energy scheduling strategy is proposed. Then, the influence of the introduction of renewable energy generation system and energy storage device on the ship power system is analyzed. Finally, particle swarm optimization and improved algorithm are used to optimize and solve the configuration problem. The relationship between the loss of power supply probability and energy excess percentage in ship power system is analyzed for the first time, which provides a reference for the optimal allocation scheme of actual ship. The results are helpful to improve the economy and system reliability of renewable energy ships.

A hybrid multimodal energy harvester for self-powered wireless sensors in the railway

The operational safety and reliability of the railway in monitoring systems are constantly increasing. However, the self-powered functioning of sensors utilizing energy harvesting technologies could be a challenge due to wireless sensors in the railway. This paper presents a hybrid multimodal renewable energy harvesting system (HHMRES) to power the wireless monitoring sensors such as accelerometer, humidity sensor, inclinometer, and light sensor alongside the railway in remote areas. The system design consists of a multimodal renewable energy system, power generation, and energy storage system. A hybrid solar photovoltaic system combined with a 3D printed wind turbine coupled with an electromagnetic generator was proposed as HHMRES to harvest solar and wind energy simultaneously. The harvested energy can be stored in super-capacitors and utilized for wireless monitoring sensors alongside the railway. A theoretical model has been developed to characterize the HHMRES. The total pressure and velocity contours were studied through the simulations in ANSYS FLUENT. The experiments were carried out to validate the performance and dynamics of the HHMRES by simulating solar radiations and wind flow with a solar simulator and the wind tunnel, respectively. The results showed that the average output power of the proposed system was 12.31 W at 17.5 m/s wind speed and 1700 W/m2 solar radiations. The techno-economic optimization of HHMRES was performed in HOMER software to find the most optimal design structure, capital cost, operating cost, and replacement cost of the proposed model. The harvester was demonstrated to have significant power output to operate wireless sensors alongside the railway.