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Maximum power point tracking (MPPT) is a very important necessity in a system of energy conversion from a renewable energy source. Every year a number of publications appear in various journals and conferences claiming to offer better and faster MPPT techniques for wind energy conversion system (WECS). This research paper provides a concise yet comprehensive critical analysis of these techniques with an in-depth review of their strengths and drawbacks. This review is unique as there has been no other research paper so far that offers such a complete and up-to-date investigation of MPPT techniques in WECS. Therefore this research paper can serve as a precise reference for the future research on MPPT for WECS.

Silicone fluids have numerous electrical applications in both energy conversion equipment and communications type apparatus. To aid engineers in the application of these fluids and to determine the general characteristics of these dielectrics, a study was made of their electrical properties. The measurements were made on fluids of commercial purity.

The feasibility of fabricating glucose-activated paper battery based on glucose-oxidase enzyme using a simple and cheap plastic laminating technology is demonstrated. Through a simple lamination process, the battery is constructed by passing a stack consisted of the magnesium, enzyme-doped special paper, copper sandwiched between two plastic films into a roller which bound the whole assembly together. The single battery can deliver a stable voltage and power output of 0.8-1 V and 0.1-0.8 mW, respectively. We can also optimize the enzyme and glucose concentration as well as the prototype design to gear up the power requirement. This novel idea of making glucose-activated battery by plastic lamination technology could offer cheap alternative power for many potential energy-powered medical devices, such as an integrated disposable bio-systems providing onboard power source for the sensing unit and detection of the analytes of interest.

Resource consumption directly impacts the cost of semiconductor manufacturing and indirectly contributes to increases in global warming. Since 1996, several resource conservation projects and surveys have been performed at SEMATECH, its member companies, and semiconductor manufacturing equipment (SME) suppliers. Significant reductions in SME resource consumption are possible, but are they enough? The International Technology Roadmap for Semiconductors (ITRS) continues to challenge new fobs and SME designers to meet ever-decreasing energy goals. The World Semiconductor Council has issued their white paper on energy suggesting normalized energy reductions for wafer fabs. To achieve measurable reductions, both factory owners and SME suppliers will need to baseline their energy consumption and establish specific targets for improvement. Target setting must include the total energy requirements for process equipment, its support components (e.g., vacuum pumps, abatement devices, chillers), and all support utilities (e.g., power, water, compressed air, etc.). To measure, track, and report the progress towards improvement goals, a total equivalent energy (TEE) tool is presented. One of the key components of the TEE methods to be addressed is the use of energy conversion factors (ECFs)

This experiment suggests that biogas-fermentation by pretreated Eupatorium adenophorum Spreng is a preferable approach compared with methane production followed by hydrogen production, only methane production, or only hydrogen production, due to its decreasing overall fermentation time, and increasing material utilization efficiency and energy conversion efficiency.

This paper presents a novel single-phase to single-phase multiconverter topology that can be applied in multiple areas. The proposed multiconverter is designed with only two soft power semiconductor switches (e.g. MOSFET or IGBT), four power diodes and a center-tapped transformer which makes it more compact in size, decrease the gate driving complexity, reduce the total equipment costs and enhance the energy conversion efficiency with minimized losses. Furthermore, the utilization of the transformer in the proposed converter mitigates the multiple AC source requirement problems and provides galvanic isolation which increases the reliability of the converter. Moreover, the presented multiconverter is applicable in various areas including electric traction as a speed controller, induction heating, AC and DC variable power supplies, etc. which signify the competence of this converter in energy conversion appliances. However, a comparative analysis of the offered converter with the existing AC-AC converters is also introduced in this paper with respect to the number of components, equipment costs, gate driving complexity, and application areas. In order to evaluate the performance of the proposed multiconverter, the simulation-based results carried out in MATLAB/Simulink are presented and analyzed in this paper with proper descriptions. Finally, a scaled-down prototype is developed in the laboratory to validate the simulation results and the feasibility of the proposed multiconverter.

Oceanic wave energy extraction through electrical generator is one of the most interesting topics in the field of power engineering. Almost all the existing relevant review paper focus on electrical generator with the working principle of electromagnetic induction or piezoelectric or triboelectric effect. In this paper, all the existing types (based on principle of operation) of electrical generator used for wave power harvesting are discussed. This paper not only covers recent progress in electrical power generation by electro-magnetic induction, piezoelectric generator, and electrostatic induction, but also presents critical comparative review as well where suitable use and weakness of each type of generators are discussed. Moreover, the application of advanced magnetic core, winding, and permanent magnets are discussed with extensive explanation which are not focused in the existing reviews. Various new constructional features of the electrical generators such as split translator flux switching, two-point absorber, triangular coil, dual port linear generator, piezoelectric, triboelectric nanogenerator, etc. are highlighted with principles of operation. It also includes emerging human intervened optimization method for determining optimum shape of generator and cooling system which is necessary to prevent demagnetization of the permanent magnet. Finally, the way of supply the generated electrical power form the generator to load/grid is thoroughly described in a separate section that would be obvious for successful operation. The comparison among all types of generators in terms of output voltage, current, scale of power production, power-frequency characteristics, power density, cascading, and approaches are tabulated in this paper.

The hybrid-series-converter-(HSC) has enhanced operating modulation-index-(MI) range as compared to the parallel-hybrid-converter-(PHC). However, the HSC is underutilized when employed for high-voltage-direct-current-(HVDC) applications, HSC-HVDC. The parallel-chain-links-(PCLs) of HSC-HVDC generate fixed voltage and the series-chain-links(SCLs) of HSC-HVDC serves only as voltage wave-shaping circuit and does not increasing the output voltage levels. Thus, energy storage requirement of HSC-HVDC is higher than PHC. The switches of HSC-HVDC undergo forced commutation and increase losses. This paper intends to extract all the advantages inherent with the HSC and utilize it to its maximum capability by operating it as a static-compensator-(STATCOM), HSCSTATCOM. The proposed HSC-STATCOM requires lesser switching devices, capacitors besides having reduced energy storage requirements and zero-voltage-switching-(ZVS) nature. A new capacitor voltage control technique during unbalanced grid conditions is also proposed in this paper. The operating principle of the proposed STATCOM and proposed control technique is validated using different simulation case studies.

This paper investigates the dynamic characteristics of AC microgrids in the presence of Constant Power Loads or Constant Power Sources (CPL/CPS). This dynamic characteristic is useful for understanding how AC microgrids behave in different operating points. If the dynamic characteristic is not desired, microgrids’ components can be tuned or proper approaches can be adopted to improve it. In this paper, the input impedances of a non-ideal CPL/CPS is mathematically derived through vigorous modeling. Moreover, the closed-loop output impedance of a distributed energy resource regulating the microgrid voltage is modelled. A unifying approach is adopted to transfer impedances of AC microgrid components to the same coordinate in order to utilize impedance-based stability analysis to assess the dynamic characteristics of AC microgrids in different operating points. Finally, simulation results are provided to validate findings.

This paper focuses on the multi-circuit HVDC transmission system which can localize DC line faults. The conventional method requires to shutdown and restart the wind power plants after the DC line faults, resulting in the long-term suspension of the power plants. This paper proposes a control sequence for enabling continuous operation of wind power plants under DC line faults in the multi-circuit HVDC transmission system. The proposed method reduces the power outage after the DC line faults. Simulation results demonstrate that the proposed method enables continuous operation of the wind power plants and reduces the power outage to 0.2 seconds.

This paper expands a previous study regarding application of modular variable filter inductor in a cascaded H-bridge low-capacitance StatCom (LC-StatCom). In this paper, the benefit of having such a filter to expand the operating capability of the LC-StatCom into the inductive region is demonstrated. A comparison between the modular filter inductor and thyristor bypassed series inductor solutions is performed through derivation of analytic expressions. The added capacity to operate in the inductive region is also validated via experimental results.

Due to easy implementation and fast dynamic response, deadbeat predictive current control (DPCC) has been got wide attention for permanent magnet synchronous machine (PMSM) drives. In order to further enhance DPCC performance, it is meaningful to compensate the voltage distortion caused by inverter nonlinearity. In this paper, an internal model control (IMC) is employed to constitute a voltage distortion estimator. In addition, the DPCC with the voltage distortion estimator is proposed. Compared with other compensation methods, the proposed method can be utilized for different PMSM speed and dc-bus voltage conditions. To verify the effectiveness of the proposed method, experimental results are carried out in this paper.

Mission profiles are widely used for the reliability analysis of power converters. Typically, to assess the converter reliability, long-term (e.g., one year) mission profiles are adopted, and it is assumed that the profiles will be repeated in future years. However, due to mission profile uncertainties, the assumption can introduce considerable errors in the estimated reliability. In this paper, the errors introduced by the above assumption are studied in detail. Furthermore, to tackle this challenge, the paper proposes using the Generative Adversarial Networks (GAN) to generate unique mission profile scenarios that capture the temporal and probabilistic properties of the real profiles. In this regard, the effectiveness of using the GAN-generated profiles to improve the accuracy of the estimated reliability is demonstrated.

Solid-State transformers (SST) consist of isolated bidirectional DC-DC Converters as a link between the Active Front End (AFE) and the DC-AC converter to adjust the voltage across the two DC links. Dual-Bridge Series Resonant Converter (SRCDAB) is one of the promising topologies for such applications. In this paper, the design methodology for SRC-DAB is explained for wide-input voltage range which can be used in universal voltage SSTs across global LV grids. The converter operates using Single Phase Shift (SPS) modulation scheme with a constant and unique switching frequency for different grid connections. The practical methodology of selecting the switching frequency, transformer turns ratio and resonant tank parameters for minimum peak semiconductor losses for the complete input voltage range has been described in this paper. The converter is designed to provide constant power output of 50 kW at 750 V for an input voltage range of 300-800 V. An experimental 10 kW prototype is shown.

A novel long distance multi-coil wireless power transfer (WPT) system with constant voltage (CV) output characteristic is designed and optimized in this paper. The CV output multi-coil WPT system mathematical model is systematically analyzed and summarized, and the system operating frequency can be calculating by this model. Through state deconstruction analysis, this paper has analyzed the distance between adjacent coils on the transmission efficiency of WPT system at a long distance. Finally, the experimental results are consistent with the theoretical analysis, and the maximum transmission efficiency is 54.2% under the transmission distance of 1.1 m.

More Electric Aircraft’ (MEA) is a trend for medium and long haul airliners, in which all functions except propulsion are powered by engine-driven electrical generators. Power systems for MEA are in the process of rapid development. Constant Power Loads (CPL) pose a big challenge for power system stability. This paper proposes a concept of a MEA power system with a common DC bus, where power sharing between generators is achieved without droop or explicit communication. The paper shows how a coordinated response can be achieved by multiple DC-DC converters under PI current control, based on the local current measurements only. It utilises advanced control concepts, including feedforward and multiple degrees-of-freedom design. The paper demonstrates stability of the proposed power system with respect to any load type, including CPL. The findings of the paper are validated by detailed simulations and preliminary experimental results.

This paper formulates a discontinuous modulation (DM) technique for cascaded H-bridge (CHB) static compensators (StatComs) with star configuration. In the CHB StatComs, capacitor voltage (CV) oscillations cannot be disregarded when using relatively small dc-link capacitors. For this reason, in this paper, DM is achieved by injecting a zero-sequence voltage (ZSV) that takes into account the inherent CV oscillations. Then, the coupling that exists between the CV waveforms and the injected ZSV is analyzed. Particularly, the steady-state reference signals for the CHB StatCom operated discontinuously are analytically calculated. The practicability of the proposed DM technique is verified experimentally.

3-Level Voltage Source Inverters (3L-VSI) have emerged as effective approach to achieve high efficiency and better harmonic distortion performance. As a State-of-Art (SoA), two types of carrier arrangement methods are used for carrier-based pulse width modulation (PWM), namely, phase disposition (PD) and alternate phase opposite disposition (APOD). PD PWM gives better performance in terms of current quality and Total Harmonic Distortion (THD) whereas, APOD PWM is more effective for suppression of Common-Mode Voltage (CMV) with the expense of increased THD. In this paper, a novel Quasi-reference PWM method for 3L-VSIs is presented which results in low CMV as that of the APOD along with the reduced THD. The proposed method can be considered as a distinct trade-off between the two SoA methods, which maintains the merits of both. This paper presents the detail analysis and experimental verification of the proposed PWM technique.

This paper analyzes the torque equation of an interior permanent-magnet synchronous machine (IPMSM), including magnetic saturation, spatial harmonics, and the variation of the magnetic energy. Based on the analysis, a torque-sensorless method is proposed to identify an IPMSM’s torque map. Since magnetic energy cannot be measured in the experiment, its effect on the torque is indirectly considered using the gradient to dq-currents. In this paper, the torque gradient is formularized with the flux-linkage map; it is verified by finite element analysis (FEA). With the formularized torque gradient, the proposed method reconstructs IPMSM’s torque map through the gradient theorem. Experiments veify the proposed method’s effectiveness.

This paper introduces a common-mode voltage reduction method based on zero-sequence voltage injection for a back-to-back three-level NPC converter. A detailed analysis in the following paper will show that the amplitude of common-mode voltage in this converter is related to the rising and falling edges of six-phase output voltage pulses, and it is reflected by pulse widths of output voltages in the waveform. When the pulse widths of six-phase output voltages meet a certain relationship, the common-mode voltage will output a higher amplitude. By injecting zero-sequence voltage, widths of output voltage pulses can be changed. According to this principle, a dual-side zerosequence voltage injection method is proposed to change output voltage pulse widths and decrease the common-mode voltage amplitude. Simulation and experimental results show that the proposed method is effective, it can reduce the common-mode voltage to 1/6 of the DC-link voltage in the back-to-back three-level NPC converter.

The interest towards renewable energy resources is increasing, and in particular it concerns wind and hydro powers, where the key point regards their efficient conversion into electric energy. To this end, control techniques can be used to meet this purpose, especially the ones relying on fuzzy models, due to their capabilities to manage nonlinear dynamic processes working in different conditions, and affected by measurement errors, uncertainty and disturbances. The design methods addressed in this paper were already developed and validated for wind turbine plants, and important results can be achieved from their appropriate design and application to hydroelectric plants. This is the key issue of the paper, which recalls some considerations on the proposed solutions, as well as their validation to these energy conversion systems. Note that works available in the related literature that consider both wind and hydraulic energy conversion systems investigate a limited number of common issues, thus leading to little exchange opportunities and reduced common research aspects. Another important point addressed in the paper is that the proposed control design solutions are able to take into account the different working conditions of these power plants. Moreover, uncertainty, disturbance and model–reality mismatch effects will be also considered when analyzing the reliability and robustness features of the derived control schemes. In fact, proper hardware–in–the–loop tools are included to simulate more realistic environments.

The spherical power source is a new type of energy conversion device. Its design concept is to integrate the functions of the spherical engine and the generator. The fuel chemical energy can be directly and efficiently converted into electrical energy output. Its spherical structure greatly improves the utilization of the space. It can be carried by one person after miniaturization design. Therefore, it has a broad application prospect. Firstly, the structure and the working principle of the spherical power source are introduced in this paper. The profile model and the machining method of the spatial guide CAM are analyzed. Then its power transmission mechanism is simulated based on the multi-body dynamics software. The prototype of the spherical power source is manufactured. The prototype runs normally during the motor drive test. Finally, the vibration characteristics of the prototype are studied experimentally. The test vibration level is 1. All vibration data meet the requirements specified in SY/T 5641-2019 Standard. Therefore, the configuration scheme designed in this paper is feasible. However, due to certain machining error and assembly error, there is a certain mechanical shock when the power source is running. In the follow-up research, some key transmission part is necessary to design flexibly, so as to ensure the smooth operation of the power source. This paper lays the foundation of configuration design for the following research.

Electrical power generation from the oceanic wave is one of the noteworthy footsteps in the field of renewable energy resource based energy conversion system. There are different technologies regarding electricity generation by using linear electrical generators along with the wave energy devices. This paper presents various control technologies of the linear generator that are widely been used for harvesting oceanic wave energy. Several controllers are discussed that are used to control the voltage, current, and power flow of the linear generator. Mathematical models of different controllers are discussed. Connection of the controller with the linear generator, input, output, outcome, and method of the controller with their pros and cons are presented as well. In addition, testing devices and their controls for the linear generator are presented with their schematic diagram. This paper would play vital role to the researcher for the future development of the linear generator for oceanic wave energy conversion.

This paper presents a process of electrical generator selection and operation for low speed renewable hydrokinetic energy resources. As more renewable energy resources enter the marketplace, generators customized towards unsteady mechanical input power and low speed operation become critical design points. Traditional power generation has relied upon steady operation to which the majority of generators are designed. The process of generator selection for low speed unsteady resources encompasses many design factors and tradeoffs. Generator selection is discussed and evaluated with respect to a low-speed vertical oscillator hydrokinetic energy resource. The complete generator selection entails selecting a generator type, modeling in simulation, and testing in a laboratory setting. This paper lays out the considerations that must be made in order to implement a successful design from the standpoint of power generation in many new and unproven renewable energy resources.

In this paper a Photovoltaic (PV) system design and performance of Al-Tafila center for care and rehabilitation (Jordan) is proposed and presented. A detailed grid connected Photovoltaic system design and analysis have been conducted and presented in this study. The comprehensive theoretical analysis and design criteria of the proposed PV system have been discussed. Main topics included, but not limited to, shading, temperature variation, radiation, and PV modules’ declination. The PV system has been simulated with PVsyst platform to optimize the energy conversion of PV system, and the simulation results show a correlation with those obtained theoretically. Furthermore, a cost analysis has been carried out in this paper; where a 20-years feasibility study is implemented which shows a short payback period and low Levelized Cost of Electricity (LCOE). SketchUp and AutoCAD platforms are used for illustration purposes of 3D and 2D modeling and area selection.

In response to the needs of park-level integrated energy planning, this paper establishes the linearization input and output models of energy conversion components for photovoltaic, wind generations, electric heating boilers, heat pumps, refrigerators, CCHP (combined cooling, heat and power), gas boilers, and energy storage components for electric energy storage, heat storage, and cooling storage. The multi-energy flow coupling input and output matrix for electricity, cooling, heat and gas is put forward to describe the coupling relationship of conversion, distribution and storage for multi-energy flows. Taking economic optimization as objective, equipment capacity and operation boundaries as constraints, a bi-level iterative mixed integer optimization planning method for integrated energy planning and operation is proposed. The case study shows that the method proposed in this paper is able to support the optimal planning of the integrated energy system planning and operation.

This paper proposes an excitation angle condition capable creating high generation efficiency for a switched reluctance generator (SRG) with low loss. This paper examines high power generation efficiency by reducing copper loss in 12/8 switched reluctance generators operated at various speeds within a wind power generation system. For this purpose, excited current waveforms and excitation angles capable of reducing the copper loss are considered. The current waveforms that appear in the duration of the excitation stage are classified into three types. The copper loss and energy conversion loop that depend on the excitation current waveforms are also analyzed. Furthermore, the correlations between the excitation condition and power generation efficiency, copper loss, excited current waveforms and energy conversion loop are considered. Finally, the excitation conditions which reduce copper loss and improve the power generation efficiency at various speeds are summarized.

The demand response realizes the flexible energy utilization on the user side and promotes the energy utilization efficiency in the multi-energy micro-grid system. This paper establishes a two-dimensions price-based demand response model with both vertical load transfer and horizontal energy conversion. Considering a variety of renewable energy resources and energy storage, this paper studies the optimal scheduling of multi-energy micro-grid system with the feedback of residual power sold to the external grid, so as to maximize the revenue of a multi-energy micro-grid system operators. A case study shows that the two-dimensions price-based demand response can not only effectively reduce the energy consumption cost of users, but also improve the benefits of multi-energy micro-grid system.

This paper presents the use of a Modular Multilevel Cascaded converter (MMCC) based Permanent magnet synchronous generator (PMSG) to harness the Oceanic Wave Energy (OWE). A direct-drive PMSG with Wells Turbine operates at a variable speed in a wide speed range and gives optimized power output using an MPPT algorithm. In this paper, MMCC is used to connect a PMSG operating at variable voltage and variable frequency to a fixed voltage fixed frequency grid in a single stage with the full control over grid-side current and machine side current. Analytical expressions supported by simulation results are presented to validate the performance of the proposed scheme.

Developing clean energy has become the key factor for China's energy transformation, and an important pathway to mitigating climate change, as well as one of the critical measures to achieve the goal of non-fossil energy consumption, with significant environmental and social benefits. Despite coal-fired power sources' dominance in China's power system, renewable energy sources such as wind and solar power, known as new renewable energy, now account for 20% of China's total installed capacity and 8% of the total electricity production. Over the past decade, China has been deploying more new renewable energies, and is now making greater efforts to integrate more renewable potential. To further clarify the life-cycle cost of different new renewable technologies and promote renewable energy utilization, this paper presents the investment efficiency and cost analysis of new renewable energy sources. First, this paper briefly reviews China's new renewable energy market situations, such as installed capacity, capacity factor, and pricing. Then, cost analysis and investment efficiency of new renewable energy technologies facing subsidy-free parity prices are studied, based on which workable price domain and investment proposals are presented. The numerical example results show that, with a downward trend of feed-in tariff and rising demand for parity prices, new renewable energy companies can still achieve win-win outcomes in generating at subsidy-free grid-parity prices and reasonably recovering their investment costs.

Distributed energy storage technology has become a very hot and important research problem. However, there is no real-time simulation modeling and experimental analysis method for the operation characteristics of energy storage system connected to power system. Real time simulation is a powerful tool for closed-loop experiment of distributed energy storage. The minimum step size of real-time simulation can reach 1 microsecond, which can meet the requirements of distributed energy storage system simulation research. In this paper, the simulation platform of energy storage system is established. The simulation model which can accurately simulate the energy storage battery and energy conversion system is established. The simulation model can be used to test the control function of energy storage. In this paper, the interface between simulator and energy storage control system is designed.

Due to the complex operating characteristics of multiple energy equipment in the integrated energy system, the reliability assessment of different energy conversion processes is more complicated than that of the power system, natural gas system, or thermal system. At this time, not only need to consider the operating risks between the various subsystems, but also need to pay attention to the problem that the fault may be transmitted through the coupling equipment, which also makes the operation risk of the integrated energy system increase sharply. In response to the above problems, this paper proposes a reliability method for integrated energy system of electricity, natural gas, and heat coupling based on coupling equipment failure to evaluate and analyze the integrated energy system, and the reliability evaluation index is used to quantitatively analyze the possibility of the energy system facing operational risks and the energy supply situation at the time of failure. Finally, a simulation example verifies the effectiveness and practicability of the method proposed in this paper.

There is a great deal of effort to develop a luxury Hybrid Electric Vehicles (HEVs) that has high fuel efficiency as well as excellent acceleration performances. Among several powertrain systems, the multi-mode hybrid systems have several operating modes to achieve high performance, which can select the optimal operating mode according to driving conditions. In this paper the operating modes of the Cadillac CT6 Plug-in with multimode hybrid system have been analyzed and, although more operating modes could be used, it was investigated why GM engineers selected these operating modes. And then, the optimal mode shifting strategy has been proposed based on powertrain efficiency with the energy conversion loss depending on the operating mode. This paper is a summary of the paper submitted to International Journal of Precision Engineering and Manufacturing-Green Technology [5].

As more and more new energy sources are integrated into integrated energy systems (IES), it is important to consider energy storage technologies in integrated energy planning systems so as to reduce energy costs. In this paper, combined heating and power (CHP), gas boiler (GB) and thermal storage (TS) are contained in this IES. According to the user's energy demand, an optimization model was established along with the minimum cost of the system as the objective function through the coordination and cooperation of various energy conversion equipment and energy storage equipment in the energy hub. This paper fully considers the constraint conditions and power balance conditions of various energy conversion equipment and energy storage equipment, and uses improved particle swarm optimization (PSO) algorithms to finally obtain the optimal economy. Finally, an example of a comprehensive energy system is used to verify the accuracy of the algorithm.

Energy storage technology is one of the key technologies of Energy Internet. Benefiting from the advantages such as high power density and long life, flywheel energy storage system (FESS) is currently one of the most popular energy storage technologies. In flywheel energy storage systems, the high speed electrical machine is the center of energy conversion, which directly affects the charging and discharging power, as well as the amount of stored energy. In this paper, a high speed permanent magnet synchronous machine (HS-PMSM) for magnetic suspended flywheel energy storage system is investigated. With a three-stage-rotor structure, the proposed machine retains the characteristics of common PMSMs, and has the advantages of easy manufacturing and assembling. First of all, the fundamental structure and working principle of the proposed HS-PMSM are discussed. Then, the basic characteristics of HSPMSM such as permanent magnet flux linkage, no-load back electromotive force, cogging torque and electromagnetic torque are analyzed by finite element method. The result shows that the proposed machine in this paper can provide considerable performance with a simple and solid structure, which is conducive to the increase of machine speed, as well as the increase of system power and stored energy, under the premise of easy manufacturing and assembling.

Power converters play an important role in harvesting energy from renewable sources. This paper presents an advanced control strategy for the power electronic converters and an energy management strategy in a microgrid having solar photovoltaic (PV) and a battery energy storage systems (BESS). The proposed advanced control of the power electronic converter ensures reduced power losses during the energy conversion process and the proposed energy management strategy ensures both the minimization of the operating cost of the system and the increased resiliency of the whole system. This paper proposes the use of a model predictive control strategy for the microgrid comprising the solar PV arrays integrated with BESSs. a magnetically linked multilevel converter (acting as the solar inverter), a full bridge inverter with advanced pulse width modulation technique (acting as the battery inverter) and an energy management system to achieve energy resiliency, minimize the operating cost and maximize the profit of the microgrid.

The power transformer is important equipment for energy conversion and transmission in the power grid and its failure will bring significant economic losses to the power system. The hot-spot temperature is a primary factor affecting the reliability and service life of power transformers. In order to calculate the temperature distribution of oil-immersed transformer windings accurately, it is required to solve a multi-physical problem, in which the magnetic field and the fluid-temperature field are coupled. In the simulation of multi-physical field of transformer, many studies usually omit the turn-to-turn insulation of windings to simplify the oil-immersed transformer model. The purpose of this paper is to investigate the effect of the turn-to-turn insulation of windings in oil-immersed transformers on the simulation results. First, a 2D axisymmetric transformer model was established in ANSYS to study the effect of low-voltage winding turn-to-turn insulation on the magnetic field simulation results. The differences of eddy current losses in the simulation were also calculated in terms of the magnetic field simulation results. It is found that the turn-to-turn insulation does not affect the magnetic field distribution in evidence from the simulation results. Besides, the values of the magnetic field and eddy current loss appear significant differences only at both ends of the low-voltage winding. Second, the fluid-temperature field of the transformer was solved in Fluent and the turn-to-turn insulation was the controlled objective in the solution process with consideration of the difference in winding losses. The simulation results show that the turn-to-turn insulation of the winding does not change the oil flow distribution in simulation. The simulation model with turn-to-turn insulation appears a gradient in the temperature distribution of the discs and a rise in the overall temperature distribution. Moreover, this paper analyzes the possible reasons for the differences in the simulation results of the magnetic and temperature fields caused by the turn-to-turn insulation. Some results and conclusions in this paper can be used in related studies and designs.

This paper puts forward to a new gravity energy storage operation mode to accommodate renewable energy, which combines gravity energy storage based on mountain with vanadium redox battery. Based on the characteristics of gravity energy storage system, the paper presents a time division and piece wise control strategy, in which, gravity energy storage system occupies a dominant position supplemented by vanadium redox batter. On the basis of the stress analysis of heavy objects and energy conversion process of gravity energy storage, the paper lists the optimization objective function of the new model. Finally, the validity and feasibility of the gravity energy storage operation mode and control strategy are verified by simulation.

The research on Solar Photo-Voltaic (PV) based Energy Conversion (SPEC) system requires an expensive and composite experimental setup. Therefore, PV source emulator is an essential component to evaluate the performance of SPEC system source under varying environmental conditions. This paper presents the design and development of solar PV Array Emulator (PVAE) using Programmable DC power supply. The PV module in the PVAE is designed with five parameter diode model. The parameters of the PV module is estimated using Real-coded Genetic Algorithm. The PV array is developed in the Multisim software and replicated with the support of programmable DC power source using LabVIEW. The proposed PVAE works on the online load tracking algorithm and does not require memory space to store the characteristic curve lookup table of the PV array. The prototype of the proposed PVAE is tested with a 800 W solar PV array along with Maximum Power Point Tracking algorithm and the performance of the developed system is reported in this paper.

Under the bottleneck situation of traditional energy development, we should make full use of sustainable new energy supply and social consumption. The new energy system is composed of many types of independent power generation systems. The efficiency, quality and time cycle of energy conversion sources are different, which leads to different energy consumption pricing. Customers' consumption behavior will consider their demand and market price to use energy reasonably, which also causes the trend change of power grid energy trend. This paper focuses on the analysis of energy consumption structure model under the new situation, so as to guide and judge the development trend of power trend. This paper analyzes the structural factors of energy consumption that can affect the change of energy flow, extracts the important influencing factors. As the limiting conditions in the optimization model, uses the fast decomposition power flow analysis algorithm to build a comprehensive energy model. Provides more accurate decision-making for energy development and distribution through online calculation of real-time data.

A bidirectional DC-DC converter with a wide- range voltage conversion ratio is proposed in this paper. The characteristic of wide-range voltage conversion ratio can be utilized in the energy conversion of retired batteries, such as electric scooters, electric vehicles, electrical buses, electric trucks etc. with different voltage levels. The proposed converter is composed of cascading a two-phase interleaved half-bridge circuit and a voltage-doubler circuit. The two-phase interleaved half-bridge circuit and the voltage-doubler circuit are defined as terminals A and B, respectively to investigate the operational stages of the proposed converter and analyze the voltage conversion ratios under different voltage-level schemes. Due to the variable structure design and control of the proposed converter, a wide-range voltage converter ratio and bidirectional step-up/step-down function can be achieved. A prototype for the proposed bidirectional DC-DC converter with a rated voltage of 150V at terminal A, a rated voltage between 25V and 1050V at terminal B and a rated power of 1100W is designed and implemented in this paper. Experimental results demonstrate that the proposed bidirectional DC-DC converter can be operated in the different modes with respect to different voltage levels. Meanwhile, the maximum conversion efficiency of above 98% can be achieved.

Energy hub has been widely used in modeling of multi-energy system and energy Internet since it is put forward, and the general model of energy hub is developed and improved in this paper. The existing energy hub model used in previous studies is established based on the steady-state operation model of the energy conversion equipment, which only considers the factors of energy distribution and conversion efficiency in energy hub, but does not consider the off-design properties of energy conversion equipment. Therefore, this paper studies the off-design characteristics of gas turbine and heat recovery steam generator in the cogeneration energy hub, and brings the off-design characteristics of equipment into the energy hub model, so as to obtain off-design analysis model of energy hub. This work has important implications for the comprehensive energy efficiency assessment of multi-energy systems and energy Internet.

Presented paper depicts the modeling, simulation of Dc-Dc converter and control of battery charging application with less oscillation during switching of MOSFET. Proposed paper deals with the implementation and design of an actual time maximum power point tracking (MPPT) for (PV) system aimed to increase efficiency of energy conversion. As the photovoltaic system has a non-linear behavior of i-v characteristic curve and because of solar irradiance and temperature changes is directly proportional to the maximum power point. Therefore, to obtain maximum power from Solar array the (P&O) Perturbation and Observation MPPT algorithm is implemented using Buck Boost converter. The charismatic characteristics of PV array at different irradiance and temperature is simulated.

Renewable energy systems like wind, solar, ocean and tidal are prone to consistent weather changes which can be abrupt and quick in nature. Extracting maximum power from generators that are powered from renewable sources can be demanding. Maximum Power Point Tracking (MPPT) is the process of harnessing the maximum power from any energy conversion system even in the most arduous weather conditions. Perturb and Observe (PO enabling us to extract the maximum power. Artificial Intelligence or Machine Learning plays a key part in these modified algorithms. In this paper, various machine learning algorithms are discussed and compared to predict a maximum power in different environmental conditions. Multilayer Perceptron reasons out to be an efficient algorithm that delivers feasible and highly accurate predictions. Furthermore, it is also discussed how this model can be coupled to a P&O module. The paper concludes by explaining this derived optimal supervised learning algorithm.

Induction motors are one of the main pieces of electromechanical energy conversion equipment, as they show features such as high reliability, long life, and robustness. One of the main techniques for identifying non-compliances in these rotary machines is vibration-based condition monitoring. The paper has focused on squirrel-cage broken bars, a typical fault in induction motors. Using an experimental set up in which this fault may be gradually introduced in a healthy motor, the paper shows how this fault changes the vibration pattern, in both time and frequency domains. The methodology based on motor current signature analysis, was modified and applied to the mechanical vibration signals. It has shown as adequate effectiveness for detecting faults when the motor load is higher than 37.5% of the nominal value. Besides that, the frequencies characteristics of the fault were found and demonstrated how important is the motor operation regime.

This paper proposes a detailed design method to build a bidirectional CLLLC resonant converter for an on-board charger (OBC). The proposed CLLLC resonant converter can realize the ZVS of the switching transistor and the ZCS of the rectifier, benefiting from its high efficiency and high power density, and can thus realize a wide output voltage range. Furthermore, the bidirectional energy transformation makes the CLLLC topology suitable for use in OBC dc-dc converters. The design method proposed in this paper is used to systematically expound the relationship between the parameters and the characteristics of the CLLLC converter. In addition, the resonance parameters are optimized according to the key indicators of shutdown current and efficiency. A prototype with a forward operation at 6.6 kW and a reverse operation at 3.3 kW is built according to the proposed design method and its characteristics are verified.

Power transformers are the core of energy conversion and transmission in power grid. Once an accident occurs, it may cause huge losses such as equipment assets and power outages, and even have serious social impact. Therefore, effective state prediction and evaluation of power transformers can guide the operation and maintenance, which has important theoretical and practical significance. In this paper, the large data analysis method is used to predict and evaluate the running state of the transformer. Firstly, the running state index of the transformer is predicted based on long-short term memory (LSTM). Then, the current and future running state of the transformer is evaluated by decision tree classification algorithm. The experimental data comes from the running data of 630 kVA transformers in a certain area. The results show that the method used in the paper can effectively predict the future running state of the transformer and evaluate the abnormal state with high accuracy, which can provide reference for actual operation and maintenance.

The paper presents design and analysis of cylindrical and rectangular permanent magnet linear transverse-flux generators of different configurations. The machines are viewed as direct-drive generators for ocean-wave energy conversion systems, and are studied by using 3D FEM and circuit software. Electromechanical characteristics of the machines such as: back EMF and power density are compared in the paper.

Global demand for electricity is constantly increasing, while the availability of conventional energy sources is becoming less every day. Renewable energy sources are imposed as one of the solutions to this problem. Wind and solar power plants are widespread and deeply studied. However, much greater energy potential is hidden in the ocean and sea energy. It is theoretically confirmed that the current global demand for electricity can completely be covered by the utilization of this type of renewable energy. Among all types of ocean energy, wave energy is one of the most promising ways for conversion into electricity. Numerous patents for wave energy conversion systems have been registered in recent years. However, many efforts are still being made in order to improve the durability, reliability and efficiency of these systems. Knowledge of the wave parameters for wave energy conversion systems is crucial. In addition, prediction of wave height and its power can be used for control algorithms and thus increase efficiency or protect the system during extreme conditions. The wave represents a stochastic random process, which is usually analyzed statistically. In this paper, a spectral analysis of the measured sea waves is performed. An algorithm for determination of the most important wave parameters is developed in MATLAB working environment. The obtained results and their analysis are represented in the paper.