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Bipolar gradual resistive switching was investigated in ITO/InGaZnO/ITO resistive switching devices. Controlled intrinsic oxygen vacancy formation inside the switching layer enabled the establishment of a stable multilevel memory state, allowing for RESET voltage control and non-degradable data endurance. The ITO/InGaZnO interface governs the migration of oxygen ions and redox reactions within the switching layer. Voltage–stress-induced electron trapping and oxygen vacancy formation were observed before conductive filament electroforming. This device mimicked biological synapses, demonstrating short- and long-term potentiation and depression through electrical pulse sequences. Modulation of post-synaptic currents and pulse frequency-dependent short-term potentiation were successfully emulated in the InGaZnO-based artificial synapse. The ITO/InGaZnO/ITO memristor exhibited spike–amplitude-dependent plasticity, spike–rate-dependent plasticity, and potentiation–depression synaptic learning with low energy consumption, making it a promising candidate for large-scale integration. [ABSTRACT FROM AUTHOR]

Reliability and packing density concerns are the two major shortcomings of spin transfer torque and spin orbit torque based magnetic memory, respectively. Voltage controlled magnetic anisotropy (VCMA) becomes energy efficient and fast, showing transcendence for the writing mechanism in the magnetic tunnel junction. Deterministic switching cannot be achieved by VCMA alone in the out of plane nanomagnet. It requires an external in-plane magnetic field, but the use of an external field is inconvenient for on-chip applications. We exploit stress and exchange bias provided by an antiferromagnetic material to mitigate the external magnetic field requisite. We perform macro-spin simulations using the Landau–Lifshitz–Gilbert equation at room temperature. We use the VCMA effect cum stress effect to investigate field free switching performance, and this improves the write error rate (WER) to 5 × 10 − 5 against WER of 0.1 with the VCMA effect alone. We studied the effects of applied voltage (amplitude and pulse width), exchange bias field, and VCMA coefficient on the switching performance in detail. This proposed two-terminal device can be helpful in achieving high cell density to implement nonvolatile magnetic memory. [ABSTRACT FROM AUTHOR]

In this paper, a modular resonant inverter is proposed for high frequency industrial heating applications. To maintain a uniform heating profile, the inverter is operated in constant power mode. A hybrid voltage and frequency control is proposed. Voltage control is used for active power tracking while frequency control is used to minimise circulating current due to reactive power and to achieve soft switching for the inverter switches. Analytical and test results are shown to verify the proposed approach. [ABSTRACT FROM AUTHOR]

ABSTRACT In low‐voltage applications using low‐Q LC filters, alias‐free capacitor voltage acquisition can be achieved, but synchronous capacitor voltage sampling under high‐Q filters used in high‐voltage applications in grid‐forming converters causes some degree of distortion and results in degradation of the power supply quality. And the inherent 1.5 sampling periods that delay in this approach limit the control bandwidth, reduce the stability region, and result in an inadequate time domain response. Despite these shortcomings, this approach is widely accepted in practice. The conclusion of this paper is that shifting the capacitor voltage sampling instant to 2 µs before the pulse width modulation (PWM) reference voltage update results in almost the same distortion as synchronous sampling. However, it can improve the dynamic performance of the system. A distortion‐acceptable univariate feedback voltage dual‐loop active damping control topology with much reduced computational delay is proposed, which is based on an internal active damping loop using a discrete lead compensator and a proportional resonance controller in the external voltage loop. [ABSTRACT FROM AUTHOR]

ABSTRACT The objective of this submission is to provide flexible reactive power regulation of a photovoltaic (PV)‐driven grid‐connected inverter. Here, inverter is realized as a synchronverter by employing frequency regulation using well‐established swing equation. However, reactive power regulation is accomplished by employing combined AC–DC voltage control in addition to traditional synchronverter control for ensuring smooth tracking of reactive power. Thus, the PV‐driven voltage source converter (VSC) will be injecting available active power as per the prevailing irradiation, temperature, and operator defined reactive power by employing proposed control. The performance of suggested control is evaluated and compared against existing control by considering realistic operational scenarios through a case study. [ABSTRACT FROM AUTHOR]

The increasing energy demand in information technologies requires novel low‐power procedures to store and process data. Magnetic materials, central to these technologies, are usually controlled through magnetic fields or spin‐polarized currents that are prone to the Joule heating effect. Magneto‐ionics is a unique energy‐efficient strategy to control magnetism that can induce large non‐volatile modulation of magnetization, coercivity and other properties through voltage‐driven ionic motion. Recent studies have shown promising magneto‐ionic effects using nitrogen ions. However, either liquid electrolytes or prior annealing procedures are necessary to induce the desired N‐ion motion. In this work, magneto‐ionic effects are voltage‐triggered at room temperature in solid state systems of CoxMn1‐xN films, without the need of thermal annealing. Upon gating, a rearrangement of nitrogen ions in the layers is observed, leading to changes in the co‐existing ferromagnetic and antiferromagnetic phases, which result in substantial increase of magnetization at room temperature and modulation of the exchange bias effect at low temperatures. A detailed correlation between the structural and magnetic evolution of the system upon voltage actuation is provided. The obtained results offer promising new avenues for the utilization of nitride compounds in energy‐efficient spintronic and other memory devices. [ABSTRACT FROM AUTHOR]

With the rapid development of 5G base station construction, significant energy storage is installed to ensure stable communication. However, these storage resources often remain idle, leading to inefficiency. To enhance the utilization of base station energy storage (BSES), this paper proposes a co-regulation method for distribution network (DN) voltage control, enabling BSES participation in grid interactions. In this paper, firstly, an energy consumption prediction model based on long and short-term memory neural network (LSTM) is established to accurately predict the daily load changes of base stations. Secondly, a BSES aggregation model is constructed by using the power feasible domain maximal inner approximation method and Minkowski summation to evaluate the charging and discharging potential and adjustable capacity of BSES clusters. Subsequently, a BSES demand assessment and optimal scheduling model for low voltage regulation in DN is developed. This model optimizes the charging and discharging strategies of BSES to alleviate low voltage problems in DN. Finally, the simulation results effectively verify the feasibility of the proposed optimal scheduling method of BSES for voltage regulation in DN. [ABSTRACT FROM AUTHOR]

In this paper, a method for determining line drop compensator (LDC) parameters for step voltage regulators and on‐load tap changers is proposed to avoid voltage violations in distribution systems with voltage fluctuations due to photovoltaic (PV) generation and electric vehicle (EV) charging. Distribution system operators need to effectively solve voltage problems caused by the widespread installation of distributed energy resources with the existing voltage regulators to construct an efficient and rational infrastructure. Our focus was on improving the method for determining the LDC parameters for the existing voltage regulators based on LDC control. A mechanism to dynamically change the LDC parameters depending on the situations in the distribution system was developed by using a mixture of experts, one of the machine learning techniques, and real‐time voltage and power flow information from information technology switches. The power flow calculations were performed using a distribution system model constructed based on the topology, loads, and generation characteristics of an actual distribution system in the Hokuriku region. The effectiveness of the proposed method was evaluated in terms of its improved effect on PV and EV hosting capacity, as well as the impact on the frequency of tap operations of voltage regulators. © 2024 The Author(s). IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

ABSTRACT The multiple‐input and multiple‐output (MIMO) DC–DC converters offer various advantages such as improved efficiency and reduced component count. However, the preference of these converters over other types of converters is dependent on the specific application and requirements. Various types of boost‐derived MIMO DC–DC converters are discussed in the literature. However, these converters are either nonisolated or isolated types. In the paper, a MIMO‐based cascaded boost hybrid interlink converter (CBHIC) has been proposed. The proposed converter includes four DC–DC boost converters that are supplied power by two input DC sources. The boosted DC output of these converters can be used independently or in a cascaded manner depending upon the requirement of the load. Further, the cascaded action of these four boost converters leads to the production of two high‐frequency AC outputs. By using bridge rectifiers and high‐frequency transformers, high‐frequency AC voltages are converted into DC. Therefore, two isolated DC output voltages can be achieved using CBHIC. The complementary operation of the cascaded boost converters results in reduction of source current ripples. The design, operating modes, and performance evaluation of the proposed CBHIC have been included in the paper. To validate the efficacy of the proposed CBHIC, a lab prototype of 400 W is prepared. The rms value of high‐frequency AC output voltage at each is isolated port is 141 V. The CBHIC exhibits an efficiency of 94.3 at 400 W. The operation of the converter during voltage control mode is further explored and its dynamic response is studies with the help of experimental results. The obtained simulation and experimental results validate the effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

To improve the voltage regulation of asynchronous generators during load switching, a Lyapunov-based control strategy has been proposed to stabilize the generator's voltage by connecting a static synchronous compensator. By constructing a Lyapunov function from the mathematical model, the error tracking problem is transformed into a global asymptotic stability problem of the Lyapunov function at the equilibrium point. The outer loop linearizes the direct current (DC) voltage control process, while the inner loop replaces integral terms with differential terms. The proposed Lyapunov method achieves linearized voltage control with a quadratic outer loop structure and the inner loop differential structure exhibits a shorter transient process, outperforming traditional methods. Simulation and experimental tests were then used, where the latter was a down-scale laboratory prototype experiment. Compared to traditional (voltage-oriented control) VOC, the outer loop (Lyapunov-function-based control) LBC reduces the DC voltage transient processes by approximately 9.4 milliseconds, while the inner loop LBC reduces both alternating current (AC) and DC voltage transient processes by approximately 2.6 ms and 8.7 ms, respectively. [ABSTRACT FROM AUTHOR]

This paper proposes goal-function-based decentralized control of microgrids. In addition to being an instrument for maintaining the grid voltage and frequency stability, each grid-tie inverter generates a current component with the aim of compensating for voltage distortion in the node where it is connected. The designed goal-function does not need to rely on the assumption that a microgrid is dominantly inductive or resistive to derive its control law, as is mostly the case with the droop-based approach. The priorities of the proposed scheme can be adjusted according to user preferences. In addition, the control algorithm is independent of network topology, can be applied in both islanded and non-islanded microgrids, and secure system scalability. The proposed method is verified by detailed simulations. [ABSTRACT FROM AUTHOR]

Flexible user-side resources are of great potential in providing power regulation so as to effectively address the challenges of reverse power flow and overvoltage issues in distribution networks characterized by high photovoltaic (PV) penetration. However, existing distributed algorithms typically implement control signals after the convergence of the algorithms, making it difficult to track frequent and rapid fluctuations in PV power outputs in real time. Given this background, an online-distributed control algorithm for the real-time power regulation of flexible user-side resources is proposed in this paper. The objective of the established control model is to minimize network losses by dynamically adjusting active power outputs of flexible user-side resources and reactive power outputs of PV inverters while respecting branch power flow and voltage magnitude constraints. Furthermore, by deconstructing the centralized problem into a primal–dual one, a distributed control strategy based on the dual ascent method is implemented. With the proposed method, agents can achieve global optimality by exchanging limited information with their neighbors. The simulation results verify the good balance between economic efficiency and voltage control performance of the proposed method. [ABSTRACT FROM AUTHOR]

Ca2+ release from the sarcoplasmic reticulum (SR) plays a central role in excitation-contraction coupling (ECC) in skeletal muscles. However, the mechanism by which activation of the voltage-sensors/dihydropyridine receptors (DHPRs) in the membrane of the transverse tubular system leads to activation of the Ca2+-release channels/ryanodine receptors (RyRs) in the SR is not fully understood. Recent observations showing that a very small Ca2+ leak through RyR1s in mammalian skeletal muscle can markedly raise the background [Ca2+] in the junctional space (JS) above the Ca2+ level in the bulk of the cytosol indicate that there is a diffusional barrier between the JS and the cytosol at large. Here, I use a mathematical model to explore the hypothesis that a sudden rise in Ca2+ leak through DHPR-coupled RyR1s, caused by reduced inhibition at the RyR1 Ca2+/Mg2+ inhibitory I1-sites when the associated DHPRs are activated, is sufficient to enable synchronized responses that trigger a regenerative rise of Ca2+ release that remains under voltage control. In this way, the characteristic response to Ca2+ of RyR channels is key not only for the Ca2+ release mechanism in cardiac muscle and other tissues, but also for the DHPRdependent Ca2+ release in skeletal muscle. [ABSTRACT FROM AUTHOR]

This paper develops a distributed secondary control strategy for direct current (DC) microgrid based on the distributed state estimation under false data injection (FDI) attacks. FDI attacks occurring on sensors, communication links, and control channels are fully considered, and a distributed state estimation–based secondary control is designed to filter out the effects of attack signals introduced in the secondary control. The secondary control is designed based on a consistent Kalman filtering algorithm, which is able to improve the accuracy by introducing corrections to the current predicted values from the previous moment of the neighbors. In addition, the consistency gain matrix is transformed into consistency coefficients to improve the correction speed. The filtered secondary control signal is fed into the primary control for voltage recovery and precise power distribution. A rigorous proof based on Lyapunov's technique shows that the method guarantees the convergence of global voltage regulation under FDI attacks. Simulation results show that the proposed method can achieve voltage recovery and accurate power distribution when the DC microgrid is subjected to FDI attacks. [ABSTRACT FROM AUTHOR]

As photovoltaic energy is clean, renewable, and less noisy, it is increasingly integrated into the grid. This integration aims to overcome energy deficits and get rid of pollution from conventional sources. In this paper, a two-stage configuration of PV energy conversion to a three-phase grid has been studied. The control of this configuration can be divided into two parts, such as DC bus control and AC bus control. The DC bus is controlled by MPPT control. The AC bus is controlled by DC link voltage control, phase-looked loop control, and voltage source inverter control. The contribution in this study aims to improve the quality of energy injected via a new hybrid approach to MPPT control. The proposed control is a combination of robust sliding-mode control and incremental inductance. Unlike conventional hybridization, the proposed control estimates correct the error upon entry of the conductance incremental control. This correction provides an adaptive incremental step for increment conductance control. The proposed control is compared with three other controls under MATLAB/Simulink. Such as incremental conductance, variable step size incremental conductance, and conventional hybrid MPPT incremental inductance-sliding mode control. The simulation results show a remarkable minimization of the ripple phenomenon and the chatter phenomenon. Thus, the quality of the energy injected into the network is improved, such as by reducing the total harmonic distortion of the current and increasing efficiency. [ABSTRACT FROM AUTHOR]

A powerful and efficient program for restoring the electrical distribution system by effectively utilizing the maximum capabilities within the system, including soft open points, distributed generation resources, and network configuration changes, can significantly reduce both the quantity and duration of lost loads caused by permanent faults. In this research study, we address the issue of distribution network restoration with a focus on soft open points (SOPs) and intentional islanding using distributed generations. This problem is formulated as a constrained optimization problem in order to determine the optimal distribution network configuration, quality of intentional islanding through DGs, control function of SOPs, and amount of load shedding. The objective is to minimize lost load while minimizing switching operations and preferably minimal islanding. Given that this problem involves multiple complexities such as combinatorial nature, mixed-integer variables, non-linearity, non-convexity along with numerous variables and constraints; we employ an evolutionary method known as simulated annealing (SA) algorithm to solve it without any simplifications or assumptions about convexity. To enhance efficiency during implementation of SA algorithm, Kruskal’s algorithm is utilized for generating radial solutions which restricts search space to feasible solutions resulting in quicker attainment of high-quality optimal solutions. Finally, the outcomes of implementing the suggested approach on the 69-bus IEEE distribution system are presented and examined. It is demonstrated that by leveraging the potential of soft open points in load transfer control and network voltage regulation, along with utilizing intentional islanding capability provided by distributed generation resources, the restoration capability of the distribution system can be greatly enhanced. [ABSTRACT FROM AUTHOR]

This paper discusses the design and analysis of a three-level LLC (TL-LLC) resonant converter for an electric vehicle (EV) charging application. The proposed two-stage onboard charger comprises an ac-to-dc power factor correction (PFC) stage, followed by the second stage required to provide galvanic isolation and dc-to-dc conversion. The PFC stage uses a bridgeless SEPIC converter with average current control and voltage mode control algorithm for achieving unity power factor (pf) operation with constant DC link voltage. In contrast, the dc/dc stage uses a three-level LLC resonant converter with a frequency control algorithm to control the output voltage. A 1 kW, 360 V output model of the proposed onboard charger is implemented and simulated in PSIM, and the obtained results are investigated and examined in detail. Results obtained from the simulation show a power factor greater than 0.99 with THD less than 5 $$\% $$ % at the input side. For TL-LLC, both zero voltage switching (ZVS) for primary MOSFETs and zero current switching (ZCS) for secondary side rectifier diodes are achieved. [ABSTRACT FROM AUTHOR]

Radial ribs are important supporting parts of umbrella antenna, and its shape is a crucial factor affecting the overall reflector accuracy. Considering the difficulty of in-orbit shape sensing, a fiber-optic shape sensing (FOSS) method for the radial rib is presented in this paper, then on the basis of FOSS a shape active control method for the radial rib driven by Macro-Fiber Composite actuators is proposed. Firstly, combining the deformation characteristics of the radial rib structure, an improved Ko displacement algorithm is proposed for its shape sensing using distributed fiber-optic. Then, establish the shape active control model with the Influence-Coefficient-Matrix method, and propose a closed-loop shape active control method with FOSS as feedback for the radial rib. In this paper, the optimization problem of solving control voltage is established by using the Least-Square method, and Root-Mean-Square error is taken as the convergence condition. Finally, numerical simulation and experiment show that the relative error of the shape sensing with fiber-optic is less than 5%, and the shape accuracy of radial rib after control is improved by more than 90% to reach submillimeter level, which verifies the effectiveness of the radial rib shape active control method based on FOSS. [ABSTRACT FROM AUTHOR]

In this work, a nine level (9-L) asymmetrical switched-capacitor multilevel inverter (ASCMLI) based induction heated (IH) autoclave for sterilization in medical applications is proposed. Due to the several benefits of multilevel inverter such as controlling of voltage magnitude and hence uniformity of heat is maintained at the load side as compared to conventional heating of autoclave. It has two common ground-connected dc voltage sources, which makes it ideal for usage in medical applications. Moreover, the development of a compact autoclave is carried out in this work that has a much reduced running time without sacrificing the quality of its sterilization. Further, the sterilization schedule for conventional and IH autoclave is presented in different temperature and pressure condition. The distributions of magnetic flux density and induced eddy current density in the multilevel inverter based IH autoclave were also exhibited. Finally, the performance of the proposed system are validated by simulation and experimental results obtained from a laboratory prototype setup. [ABSTRACT FROM AUTHOR]

In microgrids, voltage imbalance control is crucial to preserving the required level of power quality. The article presents a tracker design that mitigates the unbalance in the microgrids. The proposed microgrid model includes positive and negative sequences, whereby the positive sequences are controlled, and the negative sequence is treated as an external disturbance (whose effect must be attenuated). The uncertainty in the external disturbance is modelled in the norm-bounded form. The suggested control is based on attracting (driving) the state trajectory into a small region, including the origin (attracting ellipsoid-set). The effect of the negative sequence components is attenuated by minimizing the ellipsoid volume. When the state trajectory enters that region, it will never leave it for the future time (termed invariant-set). Two theorems were formulated for tracker synthesis that follows the desired reference and reduces the negative sequence impact. These theorems are the invariant-set method and the H ∞ approach. The validity of the suggested control is demonstrated via testing the system under various operational unbalanced scenarios, such as unbalances or faults at the load side or in the transmission lines. The simulations show the superiority of the suggested method in terms of accuracy and dynamic response when compared with the H∞. Additionally, a comparison is made between the suggested tracker and Active Disturbance Rejection Control (ADRC). • Microgrid model with positive and negative sequences is presented. • Negative sequence is treated as an uncertain disturbance. • Two developed new theorems handle this disturbance in tracker design. • A positive-sequence tracker using invariant-sets is proposed for efficient disturbance rejection. • Performance is compared to H¥ and ADRC under various operational conditions. [ABSTRACT FROM AUTHOR]

The increasing penetration of distributed energy resources poses new challenges for operating distribution systems, as high penetration levels are causing adverse grid impacts. In this context, active grid regulation, such as the smart inverters functions recommended in IEEE 1547–2018, has become necessary. In this regard, advanced monitoring techniques, such as state estimation, are promising alternatives to enhance the operation of active distribution networks. However, the lack of reliable information is a technical limitation for applying estimation algorithms to distribution circuits. Therefore, knowledge of the control mode of distributed energy resources may be valuable information to enhance the accuracy of the estimates. This paper proposes to include the volt-var smart inverter function in WLS three-phase state estimation via iterative adjustment. The volt-var control variables are introduced as pseudo-measurements in the first stage, and the second one ensures the control and state variables' compliance with the control model. The validation and benefits of the proposed method are presented via simulation results in the IEEE 34-node test feeder. [ABSTRACT FROM AUTHOR]

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Copyright of Electric Power Automation Equipment / Dianli Zidonghua Shebei is the property of Electric Power Automation Equipment Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Multilevel inverters with improved voltage quality are widely used in applications such as motor control and electric vehicles. The four-level active neutral point clamped (4L-ANPC) inverter effectively meets the demands for high power density and low device voltage stress. However, balancing the capacitor voltage and reducing its low-frequency voltage fluctuation are critical challenges that need to be addressed. To address these challenges, this paper proposes a "variable reference + zero-sequence injection" method that requires only three reference voltage signals to determine the injected zero-sequence components. Particularly, the expression of the midpoint current, regarding the modulation index and phase current amplitude, is theoretically derived. This reveals the fundamental connection between the zero-sequence voltage signal and the midpoint current, providing a theoretical foundation for the zero-sequence injection method in four-level inverters. Subsequently, a simulation model and an experimental platform of the 4L-ANPC inverter were developed to compare and analyze the waveforms of the upper and lower capacitor voltages, phase currents, and line voltages under different modulation methods. Additionally, the upper and lower capacitor voltage waveforms were examined for various modulation indices. The results indicate that as the modulation index increases, the low-frequency voltage fluctuation in the upper and lower capacitor voltages also rises. At a modulation index of 0.95, the "variable reference + zero-sequence injection" method effectively suppresses the fluctuation in the upper and lower capacitor voltages to be no more than 1 V. These experimental findings validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Under the background of high permeability, voltage feedforward control may further weaken the stability of grid-connected inverter (GCI) systems and may cause sub-synchronous oscillation in extreme cases. To solve this problem, this paper firstly considers the influence of the frequency coupling effect and voltage feedforward control, and adopts the harmonic linearization method to construct the L-type GCI sequence admittance model with PI (proportional integral) control and PR (proportional resonant) control, respectively. By comparing the sequence admittance characteristics of the GCI under two control strategies, combined with the sequence admittance model and Nyquist criterion, this paper analyzes the influence of voltage feedforward and control parameters on the stability of the GCI under two control strategies. The results show that the stability of GCI under PR control is slightly better than that under PI control. At the same time, the voltage feedforward control does reduce the stability of the GCI system under the two control strategies. Finally, the accuracy of the theoretical analysis is verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

In DC microgrids, a large-capacity hybrid energy storage system (HESS) is introduced to eliminate variable fluctuations of distributed source powers and load powers. Aiming at improving disturbance immunity and decreasing adjustment time, this paper proposes active disturbance rejection control (ADRC) combined with improved MPC for n + 1 parallel converters of large-capacity hybrid energy storage systems. ADRC is utilized in outer voltage control loops, and improved MPC is employed in inner current control loops of n battery converters. Droop control is adopted to obtain power distribution between n battery converters, and a DC bus voltage compensator is used to compensate voltage deviations and maintain constant DC bus voltage. The low-pass filter (LPF) is adopted to obtain high-frequency power as the reference for the supercapacitor converter, ADRC is also utilized in the outer power control loop, and MPC is employed in the inner current control loop. Compared with traditional observers, the voltage expansion state observer of the proposed ADRC control is independent of the system model and parameters and consequently has strong disturbance immunity, and significantly reduces voltage overshoots during power fluctuations. The MPC-based inner current control loops of n + 1 converters accelerate current response speed and significantly decrease switching losses. Simulation and experimental results indicate that utilizing the proposed control strategies, large-capacity HESS has stronger anti-interference ability, shorter regulation time, smaller switching loss, and simultaneously maintains the stability of the DC bus voltage. [ABSTRACT FROM AUTHOR]

This article proposes a voltage compensation control strategy for the distribution network based on the unified power quality conditioner (UPQC) with battery energy storage systems (BESS) to achieve comprehensive management of the power quality and improve the system dynamic responses. Specifically, aiming at that amplitude and phase jump of the terminal voltage, a capacity configuration compensation scheme is proposed to achieve voltage vector compensation. The series converter is designed to compensate for the amplitude and phase of the load voltage. The parallel converter is designed to realize power compensation and ensure that the grid voltage and current are sinusoidal and in phase. A voltage control approach based on the nonlinear disturbance observer (NDO) is developed for BESS to stabilize the DC bus voltage and improve the anti-interference performance of the current. An NDO is designed to accomplish current disturbance tracking and provide disturbance feedforward compensation. Simulations validate that the proposed approach is effective and feasible. [ABSTRACT FROM AUTHOR]

While the physical principles for regulating localized surface plasmon resonance (LSPR) are well established, dynamically tuning the LSPR in a given material post synthesis remains challenging. Herein, this study demonstrates a strategy for dynamically tuning the LSPR of Au nanostructures by selectively altering the dielectric environment. Au is integrated with an electrochemically gatable oxide, i.e., SrCoOx (SCO), into vertically aligned nanocomposite thin films via a self‐assembly growth mechanism, where Au develops into nanopillars embedded in the SCO matrix. By selectively controlling the tri‐state phase transitions of SCO matrix via varying the bias voltage polarity in ionic liquid gating (ILG), the LSPR behavior of Au nanopillars can be dynamically tuned. Specifically, gating with a negative bias fully suppresses the LSPR, while a positive bias leads to a continuous blueshift of the LSPR wavelength upon increasing the ILG duration. This work not only opens new directions for the dynamic control of LSPR of noble metal nanostructures, but also offers insight to the voltage control of multifunctionalities via structural and physical intercoupling between different phases in self‐assembled nanocomposites. [ABSTRACT FROM AUTHOR]

With the large-scale interconnection of wind power generation, the voltage problem of the power system becomes more and more prominent. Compared with adding external reactive power compensation devices, it is more economical and responsive for fans to adjust their control strategies to provide reactive power support. To make full use of reactive power supported by wind turbines, a mathematical model of doubly fed induction generator (DFIG) wind turbines is constructed to characterize the reactive power boundary of wind turbines. Then, active disturbance rejection control (ADRC) is used to generate a voltage control signal to effectively improve the unit's reactive response speed; in addition, a variable gain coefficient is used to adjust the reactive power output of the unit, which effectively improves the reactive power response speed and its control adaptability and robustness under changing power grid conditions. Finally, a wind turbine generator (WTG) simulation model is built using MATLAB/Simulink simulation software, different fault locations are perturbed, and the effectiveness of reactive power support of the proposed ADRC-based strategy is simulated and verified. The proposed ADRC-based strategy could inject more reactive power to the grid to improve the voltage. [ABSTRACT FROM AUTHOR]

A single-phase grounding fault often occurs in 10 kV distribution networks, seriously affecting the safety of equipment and personnel. With the popularization of urban cables, the low-resistance grounding system gradually replaced arc suppression coils in some large cities. Compared to arc suppression coils, the low-resistance grounding system features simplicity and reliability. However, when a high-resistance grounding fault occurs, a lower amount of fault characteristics cannot trigger the zero-sequence protection action, so this type of fault will exist for a long time, which poses a threat to the power grid. To address this kind of problem, in this paper, a hybrid grounding system combining the low-resistance protection device and fully controlled power module is proposed. During a low-resistance grounding fault, the fault isolation is achieved through the zero-sequence current protection with the low-resistance grounding system itself, while, during a high-resistance grounding fault, the reliable arc extinction is achieved by regulating the neutral-point voltage with a fully controlled power module. Firstly, this paper introduces the principles, topology, and coordination control of the hybrid grounding system for active voltage arc extinction. Subsequently, a dual-loop-based control method is proposed to suppress the fault phase voltage. Furthermore, a faulty feeder selection method based on the Kepler optimization algorithm and convolutional neural network is proposed for the timely removal of permanent faults. Lastly, the simulation and HIL-based emulated results verify the rationality and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In order to improve the control capability of distributed photovoltaic support, a distributed photovoltaic support consumption method based on energy storage configuration mode and random events is proposed. A networked and constrained parameter analysis model for distributed photovoltaic power supply control was constructed. Based on the direct flexible mode of optical storage, an AC/DC voltage level control model for distributed solar power supply control was constructed. In the operation mode of DC hybrid distribution network, the demand response tracking identification method was used to analyze the uncertain characteristic parameters of distributed solar power supply load, and combined with the planned energy storage capacity parameters, the distributed solar power supply load and photovoltaic output were estimated. By configuring the optimal energy storage capacity, adjusting the power distribution of the microgrid, and integrating the analysis of uncertain factors and random events in the energy storage configuration mode, the design of distributed photovoltaic support consumption has been achieved. The experimental results show that the distributed photovoltaic absorption control using this method has lower load requirements, can effectively reduce the exchange power of the interconnection line, and improve the configuration scale, system reliability, and economy of the photovoltaic energy storage system. [ABSTRACT FROM AUTHOR]

Microgrids (MGs) play a crucial role in modern power distribution systems, particularly in ensuring reliable and efficient energy supply, integrating renewable energy sources, and enhancing grid resilience. Voltage and frequency stability are paramount for MG operation, necessitating advanced control frameworks to regulate key parameters effectively. This research introduces a multilayer interactive control framework tailored for MGs utilizing distributed energy resources (DERs). The framework comprises primary control layers, integrating internal voltage and current controller loops, and secondary layers employing distributed finite‐time control (DFTC) strategies. Through simulation studies and comparative analyses with traditional proportional‐integral (PI) controllers, the effectiveness of DFTC controllers in reducing initial oscillations and improving stability is demonstrated. Major findings include the superior performance of DFTC controllers in stabilizing voltage and frequency parameters, optimizing power output, and enhancing overall operational efficiency. Additionally, insights into the operational dynamics of MG systems highlight the significance of advanced control strategies in mitigating fluctuations and ensuring system stability. Furthermore, the proposed method demonstrates significant efficacy improvements over conventional approaches. Voltage stability is enhanced with oscillation amplitudes less than 0.01 pu, active power control achieves a stable level of 0.93 pu, and frequency fluctuations are reduced to 0.004 Hz and effectively recovered to 0.002 Hz. These improvements suggest that the proposed method enhances system stability and control precision by approximately 95% compared to conventional methods, as it achieves much tighter control over voltage, active power levels, and frequency fluctuations. [ABSTRACT FROM AUTHOR]

This paper introduces a novel topology for a non‐isolated bidirectional multiphase single inductor (BMPSIC) DC–DC converter. The proposed BMPSIC requires only a single inductor, irrespective of the number of arms, and features reduced volume and weight compared to the total magnetics needed for a conventional converter with similar ratings. The proposed BMPSIC advantages include a high DC voltage gain without operating on a large duty cycle, voltage stress on the power switches equal to that at the high‐voltage port, easy implementation, and a lower cost for application at high‐power densities. Furthermore, this topology requires only one current and voltage control loop. This paper thoroughly details the steady‐state operating principles of the inductor current continuous mode. It provides theoretical and mathematical analysis, including a comparative analysis of the proposed BMPSIC against earlier DC–DC converters, highlighting the superior performance and efficiency of the BMPSIC. An 8‐kW laboratory prototype, designed as a proof of concept, has been meticulously developed and tested, showcasing the performance of the converter across a broad range of load variations. The efficiency measured for the rated load exceeded 98.2% at the low‐voltage port of 250 V and the high‐voltage port of 400 V. Additionally, the article features Video S1, which illustrates the functioning of the converter. [ABSTRACT FROM AUTHOR]

This paper aims to show how the switching frequency influences the properties of the digitally controlled voltage source inverter (VSI). The measurements of the Bode plots of the inverter are shown and discussed to present the existing signal delays and power conversion efficiency, depending on the switching/sampling frequency. Two types of controllers are presented, Single-Input–Single-Output (SISO) and Multi-Input–Single-Output (MISO), and adequate prediction units (the Smith Predictor for SISO—Coefficient Diagram Method and the full-state Luenberger Observer for MISO—Passivity Based Control) were used to compensate for the delays. It will be shown by comparing the THD of the VSI output voltage that prediction is useful with low VSI switching frequency (about 10 kHz) but is not important for the middle switching frequencies (about 25 kHz) or the high switching frequency (>50 kHz). This paper shows that increasing the switching frequency simplifies digital control without reasonably decreasing efficiency. The theoretical considerations, the Matlab/Simulink 2021b simulations, the final experimental laboratory verification are presented. [ABSTRACT FROM AUTHOR]

This paper investigates microgrid systems characterized by the coexistence of discrete events and continuous events, a typical hybrid system. By selecting the charging and discharging processes of the energy storage unit as logical variables, a mixed logical dynamic (MLD) model for the microgrid in islanded mode is established. Based on this model, model predictive control (MPC) theory is employed to optimize the energy management strategy, aiming to stabilize the DC bus voltage of the photovoltaic (PV) unit and minimize the switching frequency of the energy storage unit's charging and discharging processes during system operation. [ABSTRACT FROM AUTHOR]

Incorporating AC-type flying capacitors (FC) between series-connected devices is an effective way to enhance the rated voltage for high-power applications based on current source converters (CSCs). Through appropriate modulation and FC voltage control, it is possible to achieve improved DC bus voltage quality with reduced common-mode voltage (CMV) and low dv/dt. On the other hand, the parallel CSC is a popular choice for increasing the system's rated current to accommodate higher power applications. The use of interleaved modulation techniques can improve the harmonic performance of parallel converters while reducing the need for passive filters. The modular flying capacitor clamped (FCC)-CSC structure can combine these advantages, achieving higher rated power along with improved power quality on both the DC and AC sides. Moreover, the enhanced AC quality contributes to the regulation of FC voltage and further improves the DC-side voltage quality. This paper analyzes the operation principle of the parallel FCC-CSC structure and proposes an interleaved space vector modulation (SVM) method to enhance the harmonic performance of the AC output. Additionally, an optimized zero-state replacement (ZSR) based FC voltage control and a DC-link current balance strategy built on this control are introduced. Simulation and experimental results validate the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

This study proposes a frequency coupling suppression strategy for voltage source converters (VSCs) with DC‐link dynamics to address the challenges posed by the asymmetric system structures for system modelling and control design. The strategy introduces a reshaping outer loop into the q‐axis, which eliminates the conjugate voltages and currents induced by the DC‐link dynamics, to achieve decoupling of the DC‐link voltage control (DVC). Therefore, the VSC is modelled as a single‐input single‐output (SISO) admittance model, which provides clear physical insights for the analysis of admittance characteristics. Compared with the admittance matrix, the SISO model reveals the dominance of each control dynamics on VSC admittance in different frequency bands. This insight facilitates the exploration of optimized control strategies to improve the system stability margin. Based on the SISO model, a virtual admittance for compensating the negative resistive effect of the PLL is designed to illustrate the advantages of the proposed method in providing design‐oriented analysis. Experimental results verify the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

The movement towards electrification is entailing deep changes in power systems. On the demand side, the adoption of electric heating (EH) has grown rapidly in recent years. To eliminate the voltage fluctuations caused by the random switching‐on/‐off behaviors of EHs in some application scenes with special‐power‐line in low voltage distribution networks (LVDNs), a swarm‐intelligence‐based coordinated control approach of EHs for voltage stabilization with zero communication burden while guaranteeing the users' thermal comforts is researched. A novel bird‐perch‐on‐branch (BPB) ‐based swarm intelligence theory is proposed, which reveals the mapping relation between local observations and global states. On this theoretical basis, a multi‐agent reinforcement learning (MARL) framework is developed for the coordinated dispatch of EHs, where the deep‐Q‐network (DQN) algorithm is adopted to learn and generate the optimal control policy for each EH. The implementation of the proposed MADQN‐BPB approach is described based on the principle of centralized‐training and decentralized‐execution. Comparative control performances of MADQN‐BPB with a commercially available approach, and the global optimal solution are evaluated. Simulation results verify the capability of MADQN‐BPB in voltage stabilization with zero communication burden. Its control performance is close to that of the global optimal solution, and is scalable to the variations of environment. [ABSTRACT FROM AUTHOR]

A modular multilevel converter (MMC) is reflected to be an emerging multilevel topology for medium- to high-power induction motor drives due to its highly reliable structure, modularity and scalability. However, large circulating current produced in the phase arm of MMC during low-speed operation of induction motor drive is a major drawback of MMC, which leads to affect the size of a sub-module capacitor, inductor and switch rating. To mitigate the circulating current and improve the performance of MMC-fed induction motor drive, this paper proposed a new circulating current error compensator (CCEC) technique with reduced arm current peak. By proper control of instantaneous voltage between arms and DC link current, second-order fundamental frequency current harmonic from circulating current is eliminated which leads to a significant reduction in circulating current. A comparative evaluation between conventional control scheme and the proposed CCEC control scheme is presented. The performance and effectiveness of the proposed CCEC technique are validated using a MATLAB-based simulation. Scale-down laboratory experimental setup is also developed to check the effectiveness of the proposed CCEC control technique. Reduction in circulating current for entire speed range with improved DC link current profile is observed as compared to conventional circulating current suppression control. [ABSTRACT FROM AUTHOR]

The performance of neutral‐point‐clamped (NPC) converters is subject to the regulation of neutral point balance. In the literature, researchers have addressed two main modulation methods: the active space vector PWM (SVPWM) technique and the virtual SVPWM (VSVPWM) method. However, those two approaches respectively suffer from reduced DC‐link voltage utilization and poor active regulation capability. To address this, an improved VSVPWM modulation scheme with actively strong voltage regulation capability is proposed in this paper. The fast and precise control of capacitor voltages is achieved by optimizing the synthesis scheme of the virtual vectors. When there is a voltage imbalance, the proposed technique can quickly restore and maintain the capacitor voltage balance till the full DC‐link voltage utilization without affecting the converter output quality. The experimental validation results on the NPC converter have demonstrated the benefits of the proposed active VSVPWM method. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a full‐range regulation method for half‐bridge secondary series resonant converter. With the proposed method, the resonant converter can achieve full‐range regulation within a narrow frequency range regardless of the load level. Besides, the converter can be used for the battery charger systems and programmable power supply systems. The primary‐side transistors and the secondary‐side diodes are zero‐voltage switching turned on and zero‐current switching turned off, respectively. In‐depth analysis reveals the characteristics, that is, operation principle, voltage conversion ratio, component stresses, and ZVS condition of the half‐bridge secondary series resonant converter with the proposed method. Besides, the performance comparisons among the different methods are conducted to present the merits of the proposed method. Further, the performance comparisons between the half‐bridge secondary series resonant converter and primary series resonant converter with the proposed method are executed to show their superiority with different turns ratio range of the transformer, respectively. When the turns ratio is larger than 0.5 and smaller than 1, the performance of the half‐bridge primary series resonant converter is better; when the turns ratio is equal to 1, the two configurations feature the same performance; while when the turns ratio is larger than 1, the half‐bridge secondary series resonant converter is preferable. The experimental results validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper deals with the output voltage tracking problem in DC-DC boost converters under the single-loop structure, emphasizing the need for overcurrent protection. Overcurrent protection is considered as a state constraint that is applied to the inductor current. A novel current-constrained controller is proposed by designing a special dynamic controller gain that is associated with the inductor current. Unlike existing nonlinear control methods capable of implementing state constraints, the controller introduced in this paper has a relatively simple structure that simplifies execution and reduces computational complexity. In contrast to methods that limit the initial states of the system, such as invariant set theory, the proposed method expands the range of the admissible set of the initial states. Experimental results demonstrate that, under the premise of satisfying current constraints, the proposed controller has better dynamic performance and robustness when compared to the nominal controllers that do not take current constraints into account. [ABSTRACT FROM AUTHOR]

The low-harmonic (LOH) voltage of the DC link of three-phase voltage source converter (VSC) requires a large aluminum electrolytic capacitor for suppression under nonlinear AC current. Consequently, this work proposes an active decoupling control method combining DC-link LOH voltage closed loop and LOH current feedforward based on a DC–DC converter. This methodology effectively transfers the DC-link LOH voltage to the smaller-sized decoupling capacitor in the DC–DC converter, thereby reducing the number of capacitors required to stabilize of the VSC DC-link voltage. This work first investigates the relationship between the DC-link LOH voltage and the VSC nonlinear current. Second, a mathematical model for the decoupling capacitor voltage is derived, indicating that its voltage form is complex under nonlinear AC current, making direct voltage control arduous. Subsequently, the principle and design process of the proposed active decoupling control strategy are analyzed in detail. A dedicated fast-response filter structure is also utilized to extract the feedback LOH voltage and feedforward LOH current in the DC link. Meanwhile, a simple control strategy for the DC component of the decoupling capacitor voltage is proposed to improve the utilization of the decoupling capacitor. Finally, the effectiveness and correctness of the method are experimentally verified. [ABSTRACT FROM AUTHOR]

This paper proposes a smooth mode-switching method based on state trajectory control to suppress overshoot and to shorten switching time during the mode switching of LLC-C resonant converters. First, the resonant tank trajectories of the LLC and LCCL are analyzed. Second, through a transformation of the resonant tank trajectory, the optimal trajectory of the resonant tank switching is drawn. Then the switching optimization cycle time is calculated by a diagram of the optimal trajectory. Thus, the PWM conversion to the optimization cycle is controlled directly when the switching signal comes. By this control method, a smooth transition of the resonant tank voltage and current between the two modes is achieved. At last, a prototype with a rated power of 500 W is built to check the feasibility and effectiveness of the proposed switching method. Experiment results show that the current surge of the resonant tank is reduced from 12.3 to 8.6 A when the state trajectory control is applied. The voltage surge of the second resonant capacitor in parallel is reduced from 906 to 712 V. Meanwhile, the switching time is shortened by 0.21 ms, which speeds up the switching process. [ABSTRACT FROM AUTHOR]

The motor parameters of permanent magnet synchronous motor (PMSM) can be mismatched in operation due to temperature variations and magnetic saturation. The parameter mismatch leads to a significant decrease in the robustness of traditional deadbeat predictive current control (DPCC), which leads to issues such as current static error and motor vibration noise. In this paper, a model-free predictive current control (MFPCC) method based on an improved sliding mode disturbance observer (SMDO) was proposed. The method estimated the total disturbance of the system using the improved SMDO, which could effectively suppress sliding mode chattering and accelerate the convergence speed of current errors. Subsequently, the predicted control voltage was calculated using a hyper-local model and compensated for the time delay. The experimental results demonstrated that the improved MFPCC-SMDO method generated lower motor noise compared to the traditional DPCC method when the controller's inductance parameters are mismatched. [ABSTRACT FROM AUTHOR]

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Dedicating more attention to renewable energies and power electronic improvements results in increased direct current microgrids (DC MGs) application. However, DC MGs have some challenges with voltage adjustment and power sharing. To do so, a two-layer hierarchical control structure, including a new fully distributed secondary control strategy and conventional primary droop control method, is proposed and employed in this paper to share power and swiftly adjust the voltage accurately. Indeed, a distributed-averaging proportional-integral (DAPI) secondary control strategy is introduced. Another problem in DC MGs is the existence of constant power loads (CPLs), which may result in instability. To overcome the problems caused by CPLs, a term based on the output voltage of CPL is added to the proposed DAPI to prevent instability. The required control inputs are obtained using localized data of the DC bus and their neighbor’s secondary control inputs inspired by cooperative control. Besides, this strategy needs no knowledge of the microgrid topology, which enhances flexibility. For validating the proposed DAPI strategy in DC MGs, an islanded DC MG is simulated in the MATLAB/SIMULINK software. Comparing the results with those obtained from another existing method proves the performance of the proposed DAPI controller under different scenarios of plug-and-play, communication failure, and load changes. [ABSTRACT FROM AUTHOR]

This article presents an improved collaborative control to resist grid voltage unbalance for brushless doubly fed generator (BDFG)-based wind turbine (BDFGWT). The mathematical model of grid-connected BDFG including machine side converter (MSC) and grid side converter (GSC) in the αβ reference frame during unbalanced grid voltage condition is established. On this base, the improved collaborative control between MSC and GSC is presented. Under the control, the control objective of the whole BDFGWT system, including canceling the pulsations of electromagnetic torque and the unbalance of BDFGWT's total currents, pulsations of BDFGWT's total powers are capable of being realized; therefore, the control capability of BDFGWT to resist unbalanced grid voltage is greatly improved. Moreover, improved single-loop current controllers adopting PR regulators are proposed for both MSC and GSC where the sequence extractions for both MSC and GSC currents are not needed any more, and hence the proposed control is much simpler. In addition, the transient characteristics are also improved. Moreover, in order to achieve the decoupling control of current and average power, current controller also adopts the feedforward control approach. Case studies for a two MW BDFGWT system are implemented, and the results verify that the presented control is capable of effectively improving the control capability for BDFGWT to resist grid voltage unbalance and exhibit good stable and dynamic control performances. [ABSTRACT FROM AUTHOR]