This paper investigates a drive system with energy recovery which uses a 3-phase 1-kW 36-slot 12-pole distributed winding outer-rotor surface-mounted permanent-magnet synchronous motor (SPMSM) and surface-mounted permanent-magnet synchronous generator (SPMSG), which can be used in indoor exercise bicycles. In order to extend drive system operating speed range, the constant torque control, flux-weakening control, and maximum torque/voltage control are used to extend its operation speed up to 1.75 times rated speed. In addition, a predictive speed controller and a predictive current controller are proposed to improve transient responses, load disturbance responses, and tracking responses. A digital signal processor, type TMS-320F-28035, manufactured by Texas Instruments, is used as a control center for the proposed SPMSM/SPMSG drive system. Experimental results validate the feasibility and correctness of the proposed methods.

Anaerobic membrane bioreactor (AnMBR) technology is emerging as an alternative to conventional anaerobic treatment due to its complete biomass retention, short start-up time, high effluent quality, and small footprint. This paper provides a general overview of the application of AnMBRs for industrial and municipal wastewater treatment. The potential benefits of AnMBRs are discussed, such as the degradation of organic matter for energy production, the concentration of nutrients for subsequent reclamation, or the effective removal of organic contaminants for water reuse. To explore the technology for energy-neutral wastewater treatment, the recovery of methane, hydrogen, and ethanol is summarized, highlighting the problems of dissolution of methane in permeate and competition between sulfate-reducing bacteria and methanogens for organic matter. Recovery of water and nutrients for reuse, e.g., for algae production, is reported. Since membrane fouling remains a challenge in membrane operat... [more]

Nowadays, AC charging piles are widely used, and with the increasing number of charging piles, the harmonic pollution generated by them becomes more serious and affects the power quality of the grid. Aiming at the problem of harmonic control of the single-phase AC charging pile, it is decided to apply the active filter technology. The single-phase parallel active filter (PAPF) is selected according to the characteristics of the charging pile. The single harmonic detection method is studied based on instantaneous reactive power theory, and a new adaptive low-pass filter with fixed-step size is proposed to improve the performance of harmonic detection by combining the least mean square (LMS) and the least fourth-order moment (LMF) adaptive algorithms. The PAPF control part adopts the composite control strategy of inner and outer loop combined with repetitive control to complete the voltage stabilization control, harmonic tracking, and compensation. Based on MATLAB/SIMULINK, the output wa... [more]

Wind power systems participating in primary frequency regulation have become a novel trend. In order to solve the problem of the over-speed deloading (OSD) control of wind power systems failing to provide reserved capacity for primary frequency regulation while under turbulent winds, this paper analyzes the influence mechanism of turbulence characteristics on the OSD control and the relationship between the reserve capacity of OSD control and the deloading power coefficient under turbulent wind speeds, while also quantifying the relationship between the turbulence characteristic index and deloading power coefficient. The range of the deloading power coefficient is obtained accordingly, based on which improved OSD control is proposed to dynamically optimize the deloading power coefficient according to the turbulence characteristics, which improves the frequency regulation performance of wind power systems under turbulent wind speed. According to the simulations and experimental results,... [more]

Standard medium-voltage converters are operated at low switching frequencies using bulky passive components. One concept to change this involves the quasi-two-level operation (Q2O) of multilevel converters that use fast-switching semiconductors to minimize the need for passive components. The flying capacitor converter (FCC) uses SiC semiconductors and operates with Q2O to minimize passive components. In this paper, two different quasi-two-level algorithms are analyzed. A medium-voltage prototype was built and low-voltage and medium-voltage measurements were used to validate the concept. A particular focus is on the overvoltage, the dv/dt behavior of the converter, as well as the dynamic behavior.

Maximum power-point tracking (MPPT) is applied to enable effective operation of photovoltaic (PV) systems under different external conditions. MPPT is based on a control system that aims at maintaining the PV system operation in the most effective conditions of maximum power output. This paper demonstrates the effective application of a novel adaptive control approach developed to be used in the field of power electronics. The application to MPPT is developed by using a non-inverted Buck-Boost converter applied to the PV system. The novel control methodology is based on the application of the Lyapunov stability concepts. The strength of this novel control technique is confirmed by the accurate comparison among the results obtained by using the proposed solution and some controllers proposed in the literature.

Direct-drive permanent magnet machines are ideal candidates for remote renewable applications, due to their independence from gearboxes and minimization of maintenance needs. However, faults may still appear in the generator of such a machine and affect its operation and production. Not only can demagnetization cause a catastrophic breakdown if left unchecked, but it also directly impacts the output quality of generators. As such, demagnetization is a topic of great interest. This paper investigated the sensitivity of three diagnostic methods—current signature analysis (CSA), Park’s vector approach (PVA), and extended Park’s vector approach (EPVA)—for demagnetization fault detection on a coreless permanent magnet generator.

Electric vehicles (EVs) are considered as the leading-edge form of mobility. However, the integration of electric vehicles with charging stations is a contentious issue. Managing the available grid power and bus voltage regulation is addressed through renewable energy. This work proposes a grid-connected photovoltaic (PV)-powered EV charging station with converter control technique. The controller unit is interfaced with the renewable energy source, bidirectional converter, and local energy storage unit (ESU). The bidirectional converter provides a regulated output with a fuzzy logic controller (FLC) during charging and discharging. The fuzzy control is implemented to maintain a decentralized power distribution between the microgrid DC-link and ESU. The PV coupled to the DC microgrid of the charging station is variable in nature. Hence, the microgrid-based charging is examined under a range of realistic scenarios, including low, total PV power output and different state of charge (SOC)... [more]

The real-time control optimization of electrified vehicles is one of the most demanding tasks to be faced in the innovation progress of low-emissions mobility. Intelligent energy management systems represent interesting solutions to solve complex control problems, such as the maximization of the fuel economy of hybrid electric vehicles. In the recent years, reinforcement-learning-based controllers have been shown to outperform well-established real-time strategies for specific applications. Nevertheless, the effects produced by variation in the reward function have not been thoroughly analyzed and the potential of the adoption of a given RL agent under different testing conditions is still to be assessed. In the present paper, the performance of different agents, i.e., Q-learning, deep Q-Network and double deep Q-Network, are investigated considering a full hybrid electric vehicle throughout multiple driving missions and introducing two distinct reward functions. The first function aim... [more]

The application of power electronics equipment in medium voltage (MV) distribution grids can provide new management solutions for power flow control, load balancing and voltage problems. A series MV VSC-based power flow controller has recently been presented to interconnect two radial distribution feeders performing active and reactive power transfers to improve the flexibility and utilization of these circuits in a controlled and secure way. Although not previously explored, this power flow controller can integrate the functionality of a series power filter, accomplishing independent control of the fundamental power flow while isolating the harmonic content between the two interconnected feeders. This prevents harmonic pollution from one feeder from propagating to the other, improving the voltage quality. To implement the harmonic isolation, several control strategies can be used. Therefore, this paper provides a comparative analysis between two of the main harmonic control techniques... [more]

The need to reduce energy consumption in greenhouse production has grown. Thermal heating demand alone accounts for 80% of conventional greenhouse energy consumption; this significantly reduces production profit. Since microclimate affects crop metabolic processes and output, it is essential to monitor and control it to achieve both quantity and quality production with minimum energy consumption for maximum profit. The Internet of Things (IoT) is an evolving technology for monitoring and controlling environments that have recently been adopted to boost greenhouse efficiency in many applications by integrating hardware and software solutions; therefore, its adoption is thus critical in enabling greenhouse energy consumption minimisation. The first objective of this study is to improve and validate a greenhouse dynamic air temperature model required to simulate or predict indoor temperature. To achieve the first objective, therefore, an existing model was enhanced and a closed loop test... [more]

The electric machine and the control system determine the performance of the electric vehicle drivetrain. Unlike rare-earth magnet machines such as permanent magnet synchronous machines (PMSMs), synchronous reluctance machines(SynRMs) are manufactured without permanent magnets. This allows them to be used as an alternative to rare-earth magnet machines. However, one of the main drawbacks of this machine is its high torque ripple, which generates significant acoustic noise. The most typical method for reducing this torque ripple is to employ an optimized structural design or a customized control technique. The objective of this paper is the use of a control approach to minimize the torque ripple effects issue in the SynRM. This work is performed in two steps: Initially, the reference current calculation bloc is modified to reduce the torque ripple of the machine. A method for calculating the optimal reference currents based on the stator joule loss is proposed. The proposed method is co... [more]

This paper introduces an enhanced solid-state transformer topology for a medium-voltage (MV) utility grid. The main objective of the current study is to develop an improved flyback converter equipped with a quasi z-source converter (qZ_iFC) having a high-voltage conversion capability for the integration of low-input voltage to the DC link of an MV modular multilevel converter (MMC). The system integrates the quasi z-source and flyback converters by operating their existing switches complementary. Furthermore, the high-gain qZ_iFC allows for a reduction in the rated voltage of the input, as well as the use of a high-frequency transformer (HFT) with a unity turns ratio that provides galvanic isolation between the input and the output ports. Thus, using an HFT just for isolation purposes without voltage gain improves the system efficiency. In addition, a controller for (i) qZ_iFC which is regulating complementary switches to prevent the shoot-through current from reaching the HFT resultin... [more]

In recent years, the problem of environmental pollution, especially the emission of greenhouse gases, has attracted people’s attention to energy infrastructure. At present, the fuel consumed by transportation mainly comes from fossil energy, and the strong traffic demand has a great impact on the environment and climate. Fuel cell electric vehicles (FCEVs) use hydrogen energy as a clean alternative to fossil fuels, taking into account the dual needs of transportation and environmental protection. However, due to the low power density and high manufacturing cost of hydrogen fuel cells, their combination with other power supplies is necessary to form a hybrid power system that maximizes the utilization of hydrogen energy and prolongs the service life of hydrogen fuel cells. Therefore, the hybrid power system control mode has become a key technology and a current research hotspot. This paper first briefly introduces hydrogen fuel cells, then summarizes the existing hybrid power circuit to... [more]

Power generation from river hydropower plants depends mainly on river flow. Water fluctuations in the river make the yield process unpredictable. To reduce these fluctuations, building a small reservoir at the river flow of the hydropower plant is recommended. Conventionally, classic single-pond models are commonly used to design run-of-river hydropower plants. However, such models are associated with fluctuations, sagging, and irregular power fluctuations that lead to irregular water fluctuations. This research proposes a novel idea to replace the single-pond model with a three-pond model to increase the plant’s overall efficiency. The three-pond model is developed as a three-tank nonlinear hydraulic system that contains the same amount of water as a conventional single pond. It also has the advantage of minimizing the run-of-river power plant’s dependence on river flow and increasing efficiency by trapping swell and turbulence in the water. To further increase the efficiency, the dev... [more]

This article deals with fault detection and the classification of incipient and intermittent open-transistor faults in grid-connected three-level T-type inverters. Normally, open-transistor detection algorithms are developed for permanent faults. Nevertheless, the difficulty to detect incipient and intermittent faults is much greater, and appropriate methods are required. This requirement is due to the fact that over time, its repetition may lead to permanent failures that may lead to irreversible degradation. Therefore, the early detection of these failures is very important to ensure the reliability of the system and avoid unscheduled stops. For diagnosing these incipient and intermittent faults, a novel method based on a Walsh transform combined with a multilayer perceptron (MLP)-based classifier is proposed in this paper. This non-classical approach of using the Walsh transform not only allows accurate detections but is also very fast. This last characteristic is very important in... [more]

This paper presents a comprehensive model predictive control (CMPC) method to control a three-phase four-legged inverter (TP4LI) for PV systems. The proposed TP4LI model aims to predictively model and control switching frequency and higher voltage/current switching to reduce losses. The CMPC model can be operated in four modes, namely standard MPC mode (Mode I), switching frequency reduction (SFR) mode (Mode II), high voltage/current switching loss reduction (SLR) mode (Mode III), and SFR plus SLR mode (Mode IV, a combination of Modes II and III). The proposed CMPC approach controls the TP4LI to (1) successfully track balanced and unbalanced reference currents with balanced or unbalanced loads; (2) reduce switching losses; and (3) keep the generated current total harmonic distortion (THD) within the industry’s recommended limits. The TP4LI model with the CMPC approach was verified and validated in the MATLAB/Simulink for a PV system. The simulation results show good tracking and perfor... [more]

In bearing fault diagnosis, ensemble empirical mode decomposition (EEMD) is a reliable technique for treating rolling bearing vibration signals by dividing them into intrinsic mode functions (IMFs). Traditional methods used in EEMD consist of identifying IMFs containing the fault information and reconstructing them. However, an incorrect selection can result in the loss of useful IMFs or the addition of unnecessary ones. To overcome this drawback, this paper presents a novel method called combined modes ensemble empirical mode decomposition (CMEEMD) to directly obtain a combination of useful IMFs containing fault information. This is without needing to pass through the processes of IMF selection and reconstruction, as well as guaranteeing that no defect information is lost. Owing to the small signal-to-noise ratio, this makes it difficult to determine the fault information of a rolling bearing at the early stage. Therefore, improving noise reduction is an essential procedure for detect... [more]

With the advancement of completion technology for horizontal wells in bottom water reservoirs, Autonomous Inflow Control Devices (AICDs), which have achieved good results in recent years, have been widely used in the oil fields of the eastern South China Sea. Although some mathematical methods can be used to predict the production performance of horizontal wells, there is no dynamic prediction method for the production performance of horizontal wells completed with AICDs. In this work, a mathematical model of porous flow in the reservoir, nozzle flow in the AICD, and pipe flow in the horizontal well is established, and then a new model is presented for predicting the dynamic performance of horizontal wells completed with AICDs in bottom water reservoirs. The new coupling model is compared with two horizontal wells completed with AICDs in the bottom water reservoirs of the eastern South China Sea, and the results indicate that the accuracy of the new model is sufficiently high to provid... [more]

The exploration and development of Gulong shale oil in the Songliao Basin has achieved a major breakthrough, with the result that a national shale oil demonstration area is being built. The shale in the Sanzhao Sag is abundant in organic matter and is an important replacement area. For this reason, it has recently become a focus for research and exploration. Compared with the Gulong Sag, the Qingshankou Formation in the Sanzhao Sag is relatively immature, and comparatively little is known about its pore structure. For this study, well ZY1, a key well in the Sanzhao Sag, was selected as the research object. Thin section observation, high-resolution field emission scanning electron microscopy, Modular Automated Processing Systemimaging, X-ray diffraction of whole rock and clay, TOC pyrolysis, and Low-pressure N2 adsorption were used to investigate the pore structure in the sag to determine the factors influencing pore development. The principal understandings are as follows: (1) The Qing... [more]

Humans have always been searching for new and efficient ways to convert fuels into usable energy. Solid oxide fuel cells, energy conversion devices capable of generating electrical energy, are widely used due to their high thermal energy production. In this research, fuzzy control was used to manage the voltage and current of solid oxide fuel cells. Simulations were conducted in two evaluation modes: checking the voltage, current, and power of the fuel cell, with and without the use of fuzzy control, and analyzing maximum power point tracking (MPPT) using fuzzy control. In the second mode, when connected to the load, the performance of the fuel cell was evaluated in the transient state, and the role of the controller was clearly visible According to the current−power characteristic of the fuel cell, which is a nonlinear curve and has a maximum point, and by using the fuzzy controller and the appropriate selection of input and output functions, this research aimed to make the system wor... [more]

Two 75 t/h medium-temperature separated circulating fluidized bed boilers burning Fujian anthracite were upgraded with low NOx combustion (LNC). By reducing the effective cross-sectional area of the air distributor (from 13.43 m2 to 11.38 m2), improving the secondary air rate (from 40% to 45%), adjusting the secondary air supply method (adding a layer of upper secondary air, raising the height of the lower secondary air nozzle (0.4 m), and increasing the secondary air speed (from 48 m/s to 54 m/s), the reform of low nitrogen combustion was carried out. The transformation achieved remarkable results, i.e., the original NOx emission concentration can be controlled between 140−160 mg/m3 after the transformation, and the lowest value is below 120 mg/m3.

All requirements for the express control of unstable hydrocarbon media and devices for their implementation to obtain reliable measurement results are determined. The features of the control of volatile hydrocarbon media and their mixtures with industrial small-sized refractometers operating on the effect of total internal reflection are considered. The new method for determining components and the ratio between concentrations of them in a mixture of volatile hydrocarbon media is developed. There are no analogs to this method in the world. This method allows determining the presence of one volatile hydrocarbon medium in another in a ratio of 1% to 99% or more. The new design of a small-sized refractometer has been developed, which makes it possible to measure the refractive index in visible light. In the refractometer’s newly developed design, the refractive index measurement range of a condensed medium is from 1.2500 to 1.7000 (measurement error 0.0004). New dependencies of change in... [more]

The proposal of the memristor, considered as the fourth basic circuit element, suggests a new possibility for the design of high-performance power electronic systems. However, it also brings new challenges. At present, more and more electrical equipment and systems have demonstrated that their external characteristics can exhibit “8”-shaped hysteresis loops and can be regard as memristive equipment and systems. In order to satisfy the requirements of controllability, flexibility, efficiently, and so on, most memristive equipment and systems are not directly connected to the power grid but instead obtain their own required powering through various forms of power electronic converters. Note that memristive loads are distinctive and demonstrate unique nonlinear behaviors. Similarly, there can be nonlinearity from the resistor (R), inductor (L), or capacitor (C) load, but there is no combination of only R, L, and C that could produce memristive characteristics. In particular, the memristan... [more]

Regulating the parameters of the atmospheric pressure plasma jet (APPJ) is meaningful for industrial applications. Since plasma is a typical functional fluid in the magnetic field, it is possible to control the discharge characteristics via the Lorentz force. In this study, the effects of a locally divergent magnetic field on the generation and propagation of APPJ were examined experimentally. The experiments used a coplanar dielectric barrier discharge (CDBD) device driven by a 30 kHz AC high-voltage source to generate a helium APPJ. A locally divergent magnetic field of 250 mT (maximum) was applied coupled with the electric field, and noticeable enhancement was observed. The results showed that the magnetic field changed the motion state of electrons and promoted collision ionization, leading to a 40% improvement in the APPJ length (0.6 cm) and a 23% increase in the intensity of line O (777.2 nm). In addition, the spatiotemporal evolution and flow field of APPJ were diagnosed by ICCD... [more]