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Modern power systems, referred to as cyber-physical energy systems (CPESs), are complex systems with strong interdependencies between power and information and communication technology (ICT) systems. CPESs also have dependencies between the essential grid services. For instance, coordinated voltage control depends on state estimation, which depends on measurement acquisition. Since the operation of CPESs is largely influenced by these grid services, assessing their performance is crucial for assessing the performance of a CPES. Most of these grid services are enabled by the ICT system, i.e., they rely to a high degree on ICT. Hence, properties such as availability, correctness and timeliness, which depend on the involved software, hardware and data of the ICT system, must be considered for assessing the performance of an ICT-enabled grid service. Disturbances and repairs in CPESs impact these properties, which can then propagate and affect the performance of a grid service as well as other dependent grid services. There is, therefore, a need to model the influence of the properties of software, hardware and data on ICT-enabled grid services for single services as well as across several services, resulting in a propagation of these parameters. Current literature lacks such a model, which can used not only to investigate but also to visualise the impact of these properties on the overall perfromance of a grid service as well as other dependent grid services. This paper proposes a meta model for assessing the performance of ICT-enabled grid services, which can be instantiated for different grid services considering their dependencies. A multi-dimensional operational state space, which serves as a visualisation of the performance of grid services in terms of their state trajectory, is also proposed in this paper. The contributions are then demonstrated by a case study with a state estimation service and the widely-used CIGRE medium voltage benchmark power grid augmented with an ICT system. Three scenarios with disturbances are presented to show the benefits of the contributions. Specifically, the performance of the state estimation service considering the disturbances is investigated using the meta model, and the change in performance is visualised as trajectories using the operational state space. These contributions enable new possibilities for planning and vulnerability analyses: property changes in parts of the ICT system can be simulated to investigate their consequences throughout the ICT-enabled grid services. A trajectory representing their performance can then be visualized in the state space based on which measures could be implemented to potentially improve the resilience of the service against the considered disturbances. [ABSTRACT FROM AUTHOR]

This paper proposes a new approach for evaluating distribution voltage regulators using quasi-static hardware-in-the-loop (HIL) simulation. Distribution voltage regulators are used to control the voltage using tap change transformers and are equipped with static control algorithms in order to accomplish different configurations of the distribution electric grid with typical load profiles. The growing penetration of renewable energy in electrical distribution systems is a great challenge for this equipment, and it becomes paramount that its measurement and control algorithms adapt to this new reality. Hardware-in-the-loop testing (HIL) techniques could be used for assessing the performance of the voltage regulator equipment. Most applications of HIL are concerned with accessing the dynamics of electrical system including not only grid modeling, but also the real equipment involved and should be used to test the efficiency of voltage regulation. However, a more simplified approach concerning the HIL tool could be applied to testing distribution voltage regulators in the laboratory prior to installation, evaluating the performance of algorithms and equipment by conducting quasi-static simulations. This paper presents this approach, joining NI LABVIEW laboratory controller software (National Instruments, LabVIEW. Available at https://www.ni.com/pt-br/support/downloads/software-products/download.labview.html#460283, 2023) and an open-source program OpenDSS (The Electric Power Institute, OpenDSS. Available at em https://opendds.org/, 2023). The effectiveness of quasi-static HIL platforms for assessing several aspects of static voltage tap regulators before installing them in the electric grid is demonstrated. The major advantage is the smaller computation complexity of a static simulations compared to dynamic simulators, allowing simpler hardware requirements. In this sense, a large number of medium to long term simulations could be easily performed providing a broader view of the behavior of the electric system including voltage regulators. [ABSTRACT FROM AUTHOR]

A modified conceptual structure of MUPFC for controlling the voltage sags in interconnected power systems is presented in this paper. For this purpose, the conventional UPFC is distributed through several series and one shunt converters. By this way, the higher frequency components are removed which only the 3th-order is remained. Also, by using single-phase series converters, better dynamic performances with proper reliability are provided. So, there are more redundancy possibilities through different operating conditions. The proposed single-phase series converters are floated from the ground which there is not required high-voltage protections equipment through transmission lines resulted in lower initial and operational costs compared to conventional UPFCs. Real-time ability of the proposed scheme is investigated through a 3-phase transmission line stressed by fault events in which by distributing the series converters through the line, the ability of MUPFC through time domain simulations is evaluated. Results present proper performances of the proposed controller scheme for voltage sags fast restoration with high damping ratio. [ABSTRACT FROM AUTHOR]

In this paper, the application and design of a high-power factor isolated Ćuk converter-based LED driver are realized for up to 50 W power. For the power switch of the PFC isolated Ćuk converter, traditional Si and silicon carbide (SiC) MOSFETs, which are wide bandgap semiconductors, are used and compared. The application is conducted using a dsPIC30F4011 microcontroller including PI voltage control. A current sensor is added to limit maximum current. Moreover, PI control parameters are selected by genetic algorithm to avoid a complex mathematical procedure for controller design. The power LED model derived in this paper is used for the PI parameter selection process. In addition, the input side inductor of the converter is operated in discontinuous conduction mode, and the switching frequency of the power switch is 57 kHz. With the experimental setup, the total harmonic distortion (THD) of grid voltage and current, power LED voltage and current, switch voltage, and input side inductor current are shown for both the SiC and Si MOSFETs and compared. It is concluded from the application that the SiC-based driver gives better results than the Si-based driver on the basis of THD and efficiency. Further, both applications provide limits of IEC61000-3-2 C class standard. [ABSTRACT FROM AUTHOR]

Hybrid ac/dc microgrid (HMG) comprises ac and dc microgrids (MGs) interconnected through an interlinking converter (IC). In islanded operation mode of HMG, a coordinated control structure must be implemented to realize voltage and frequency control in ac MG, voltage control in dc MG, active and reactive power sharing among ac sources, active power sharing among dc sources, global active power sharing among dc and ac sources, and reactive power sharing among ac sources and IC. To realize these objectives, a new coordinated control based on master–slave approach is proposed in this paper. In this method, the master source of each MG broadcasts its relative power loading as a common signal to the slave sources of the same MG and IC through a unidirectional low-bandwidth communication network. Based on this information, the slave sources and the IC adjust their operating point. The proposed method provides accurate power sharing as well as zero voltage and frequency deviation. It does not require a centralized control unit and features plug and play capability. The derivation of the proposed method is thoroughly discussed in this paper. Time domain simulation results based on CIGRE benchmark MG are presented to validate the proposed control strategy. [ABSTRACT FROM AUTHOR]

This paper proposes a discrete space vector modulation and optimized switching sequence model predictive controller for three-level neutral-point-clamped inverters in grid-connected applications. The proposed strategy is based on cascaded model predictive control (MPC) for controlling the grid current while maintaining the capacitor voltage balanced without weighting factor. To enhance the closed-loop performance, the external MPC evaluates 19 basic and 138 virtual vectors (VV) of the proposed space vector method. The optimal control voltage is then selected using an extended deadbeat method to reduce the execution time of the proposed control algorithm. By using the discrete space vector modulation principle, the VV are synthesized based on switching sequence (SS) and are divided into negative and positive SSs considering their impact on the neutral point (NP) potential. The inner MPC evaluates both types of SSs and selects the one that keeps the capacitor voltage balanced. Various controllers are evaluated and compared against the proposed control strategy. The results show that the proposed strategy improves performance without weighting factor, while maintaining a total harmonic distortion of current to be less than 2%. Compared to the modulated MPC which provides the same fixed switching frequency, the proposed controller reduces the computational burden by over 50% while also providing better NP voltage balance accuracy. [ABSTRACT FROM AUTHOR]

In this paper, an impulsive control algorithm with time-delay is proposed to alleviate the issue of interrelated state variables and the adverse effect of input voltage or load perturbations on output in the highly nonlinearity of the DC converter. The impulsive control is introduced concerning the state information of the control system, while the stability criterion is established by employing the average dwell time. The control principle similarity of the delayed impulsive effect and the spiking neural network are elucidated. Unlike the already existing control methods, such as proportional–integral (PI) control and sliding mode (SM) control, we leverage the state information of the switching state drive system in recent history at every sampling moment to conduct impulsive control with accurate and swift error feedback. Three typical controls are executed on the output load and source voltage operating point, characterizing the advantages superior to the PI and SM control algorithms. Hence, the proposed algorithm outperforms others in system performance indicators such as output voltage step-up, step-down, settling time and ripple. In terms of the variation of source voltage and irradiance in the photovoltaic system, the verification of voltage control stability is given in the case of the maximum power point module of the photovoltaic system, exhibiting minor output voltage ripple and shorter transient change time. [ABSTRACT FROM AUTHOR]

The uncertainty of solar generation is a challenging issue for the operation and control of distribution systems. Also, because of the large number of control and operation variables in advanced distribution networks, the centralized optimization technique requires high computational capabilities. In this paper, a distributed voltage regulation approach in a distribution system based on the predictor corrector proximal multiplier (PCPM) algorithm has been presented. This paper focuses on the voltage rise in distribution systems with high penetration of photovoltaics. The proposed method uses a clustering approach to divide the network into partitions based on the coupling degrees among different nodes. The optimal reactive power control strategy is conducted in each partition and integrated using PCPM. The proposed method is tested on 69 and 123 nodes IEEE distribution test systems. The results confirmed that the proposed method achieves the optimal solution with the same accuracy as the centralized method but in a much shorter computation time. [ABSTRACT FROM AUTHOR]

This paper presents a delay-locked loop (DLL) with multiple radiation-hardened techniques. A radiation-hardened charge pump (RH-CP) and a radiation-hardened voltage-controlled delay line (RH-VCDL) are proposed to mitigate effects on DLLs caused by single-event transient (SET). A lock detection module (LDM) is designed in the RH-CP to separate CP and VCDL when the DLL is locked. Thanks to LDM, the voltage transients caused by ion strikes on CP can be prevented from effecting the control voltage of VCDL and causing inverted lock error. A SET correction module (SCM) combined with sliced delay cells is used in the RH-VCDL to select the uncorrupted output and avoid missing pulses errors occurring at the output of DLL. The proposed DLL is designed in 22-nm CMOS process with an operation frequency of 5 GHz. Simulations at linear energy transfer (LET) between 40 and 100 MeV-cm2/mg show that RH-CP eliminates inverted lock error and RH-VCDL mitigates missing pulses generated by the DLL after ion strikes effectively. [ABSTRACT FROM AUTHOR]

Renewable energy-based power systems, despite their numerous advantages, can lead to problems such as frequency fluctuations, voltage drops, and unstable power outputs. This paper suggests a control method for a doubly-fed induction generator (DFIG), equipped with battery energy storage system (BESS) to frequency, voltage control, and improve the fault-tolerant ability. In the proposed strategy, the main purpose is to provide a method for decoupled control of voltage and frequency of the rotor before injected into the network as well as to improve network stability in the presence of stabilizers and BESS. The proposed control strategy is applied to BESS and the rotor side of the converter of DFIG. In this strategy, each loop controller used a conventional PI controller with additional stabilizers to damp out the oscillations of frequency and voltage. In such a way, under various disturbances condition, system in the presence of a BESS has a fast response with fewer range of oscillation. Finally, parameters of the controllers and stabilizers are adjusted simultaneously by an intelligent algorithm. All the results are obtained by simulation in real-time condition with Simulink of MATLAB 2016b. [ABSTRACT FROM AUTHOR]

The ancillary services are becoming more important due to the increasing integration of non-dispatchable and intermittent renewable energy sources. Such behavior under deregulation necessitates the procurement of these services suitably. This paper presents the multi-objective procurement of voltage control ancillary service in a dynamic pool deregulated system that is contingent to wind and solar power generation uncertainties. The shunt capacitors bid to supply this service and their switchings, although restricted due to life expectancy, depend on locational marginal prices. An improved multi-objective artificial electric field algorithm, which adopts the concept of Pareto-based non-dominated sorting, is presented to co-optimize total cost and voltage deviation. The particle's positions are updated through randomly picked Pareto solution to enhance exploitation capability. The sign and reorder mutation operations are employed to maintain diversity in the population, improve exploration, and evade local optima trap. The performance is investigated for different levels of wind and solar penetration on IEEE 30-bus and IEEE 118-bus test systems. The convergence of presented algorithm is analyzed and compared with other algorithms through statistical metrics and associated boxplots. [ABSTRACT FROM AUTHOR]

A high gain two-phase interleaved coupled inductor-based DC-DC converter step-up low input voltage sources like PV array and fuel cell in distribution generation system (DGS). The converter operates for a wide range of load changes when it is part of DGS. At light load, the converter operates in discontinuous conduction mode (DCM). A small-signal model (SSM) is required in both continuous conduction mode (CCM) and DCM to know the complete dynamic behavior of the converter. Steady-state and small-signal analysis of the two-phase interleaved coupled inductor boost converter (ICIBC) is quite complex when the converter operates in DCM. This paper presents the complete derivation of SSM of a two-phase ICIBC-based high step-up gain converter in DCM. The conditions of the converter operating in DCM are discussed. The small-signal model of two-phase ICIBC is derived using the state-space averaging method. The control-to-output voltage transfer function and steady-state voltage gain of the two-phase ICIBC are derived. When the converter operates in DCM, it eliminates the right half plane zero from the control-to-output voltage transfer function. Thus, it improves bandwidth and stability margin. Thus, single loop voltage control is sufficient to achieve regulated output voltage with faster response for all operating ranges of DCM. The laboratory prototype of two-phase ICIBC is implemented to step-up 24 V to 100 V at a power level of 300 W. The experimental results of two-phase ICIBC are obtained in DCM and CCM with step-change in load to validate the derived small-signal model. [ABSTRACT FROM AUTHOR]

This paper presents an application for the control of a voltage source converter (VSC) through the synchronverter approach. The objective is to show that such an approach is pertinent to handle this type of converters, especially important nowadays that such devices are practically permeating small as well as large electrical networks. The paper helps to demonstrate that the proposed control strategy is capable of satisfying the requirement that a modern VSC must contribute to the Volts/Var regulation problem in the smart grid, which represents a significant challenge. The application is carried out in the context of the hardware-in-the-loop using Matlab/Simulink. The results state the VSC performance under different operating conditions and become quite relevant. [ABSTRACT FROM AUTHOR]

IoT and wearable medical devices frequently require ultra-low power solutions that can support long spells of inactivity. This study presents a buck converter to control power stages using a novel pulse frequency modulation (PFM) system that reduces switching losses for low-power systems. The modulation of high and low-frequencies was demonstrated, where the high-frequencies exhibited better energy transformation between the inductor and capacitor, and the low-frequencies could be adjusted for different current loads, to reduce switching losses. This circuit is optimized for light load applications. Using voltage control oscillation (VCO), the frequency range of 0.5 MHz – 2.0 MHz can be adjusted to influence conversion efficiency for different loads. The design was simulated and then fabricated using TSMC 0.18um process. The core size was about 1500 × 1000um that includes power MOS. Measurements result an average conversion efficiency of 91% under a load of 0.1 mA – 10 mA. This chip is suitable for battery-based IoT systems, or wearable medical devices. [ABSTRACT FROM AUTHOR]

This paper proposed two PWM control scheme which is the Voltage Oriented Control (VOC) and Direct Power Control (DPC) on a heavy loaded LV-distribution network with photovoltaic (PV) integration in Malaysia. The surge in demand of power supply is overcome by deploying more PV to fulfil the load demand. However, this could give rise to power quality issues that can affect the stability of the grid. The focus in this work is to solve voltage dynamic concern which results in over and undervoltage problems within the distribution network and at the same time to evaluate on the performance of both control schemes under a heavy loaded condition. A 33 kV Malaysian LV-Distribution model integrated with PV is constructed to serve as a base model in this paper. From the base model, a load flow analysis is conducted in order to locate the weakest bus. The two proposed control schemes are introduced into the weakest bus in the grid system, and its performance of the controller will be evaluated based on three aspects such as compensation margin, voltage and current total harmonics distortion (vTHD and iTHD) and lastly the compensated voltage levels. It is shown that VOC control scheme has outperformed DPC due to a wider compensation margin and its ability to achieve the desired reference voltage with a faster settling time under heavy loaded condition. Therefore, the proposed PWM control scheme of both VOC and DPC under a heavy load scenario could be set as a benchmark to provide impactful insights and findings towards an actual implementation of the application within a distribution network or distributed generation. [ABSTRACT FROM AUTHOR]

This paper presents a fuzzy control system to automate the operation of capacitor banks installed in a transmission substation. This automation intends to standardize operation and control voltage at the substation output bus. The system was implemented and tested with real data from a 345/138 kV transmission substation. The results obtained through the simulations are compared with the manual commands executed by the technicians from an operation center in Brazil. The outcomes showed the effectiveness of the proposed system to maintain the bar voltage considering the current load regime. In addition, the capacitor banks' operations numbers were reduced and standardized. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic stability of the power systems is improved through the rotor side convertor voltage control of a number of doubly fed induction generators (DFIGs). The multi-input backstepping method is used to design the control laws. Using the particle swarm optimization algorithm, the proposed control parameters are optimized to achieve a better performance. This optimal control law leads to a significantly improved performance in comparison with linear control methods such as state feedback control which implement optimized pole placement by linear matrix inequality design. The offered method results in a faster convergence rate and also robustness against changes in the operating points. The performance of the presented control scheme is validated in a standard 9-bus IEEE power system, with a DFIG located in bus number 9. [ABSTRACT FROM AUTHOR]

The unpredictable variations in the wind speed consistently require a significant endeavor to enhance the control performance of the wind power conversion system (WPCS). This paper aims to evaluate the performance of a permanent magnet generator-based WPCS making use of the vector control schemes where, the internal loop employs hysteresis current controller and the external loop employs proportional-integral (PI) controller. In order to devise a control system with most favorable closed-loop poles meant for desired control performance, the parameters of the PI controllers involved in the external speed and DC link voltage control loops have been designed incorporating explicit damping specification via pole-placement. The offline simulation results have been produced in MATLAB environment using Simulink to demonstrate the effectiveness of the proposed PI controller design. The offline simulation results are then validated through Typhoon HIL402 real-time hardware simulator. It has been verified that the vector control schemes incorporating the PI controller parameters as designed herein allows the WPCS to operate stably with desired control performance while extracting the peak power continually even under rapidly changing wind speeds. [ABSTRACT FROM AUTHOR]

Voltage regulation issue in the distribution network is considered as a challenge that is associated with high penetration of the distributed generations (DGs). The widespread of the DGs led to influence the operation of the reactive power compensation (RPC) devices and the on-load tap-changers (OLTCs) and significantly affected the voltage profile. Therefore, obtaining the suitable control settings for the OLTC and the RPC should be reconsidered considering the impact of the DGs. This paper proposes a strategy for coordinating the operation of the OLTC and the RPC with DGs in the distribution networks. The proposed coordination strategy obtains the optimal values of the active power generated from the DGs, the reactive power injected from the switched capacitors (SCs), and the tap settings of the OLTC by using the multi-objective particle swarm optimization (MOPSO). The objective function is to minimize the total active power losses for all lines and the total voltage deviation for all nodes in the distribution network. The proposed coordination strategy is tested on the modified IEEE 33-node test feeder and a practical distribution feeder extracted from the North Delta Electricity Distribution Company in Egypt. A MATLAB code is built in this paper for simulation of the case studies and for determining the optimal parameters. A comprehensive comparison between the proposed MOPSO and the mixed-integer linear programming (MILP) method for different operating conditions of the distribution network is made. The results demonstrate that, the proposed strategy decreases the power losses, improves the voltage regulation and provides efficient coordination of DG with the voltage regulating devices; SCs and OLTC. [ABSTRACT FROM AUTHOR]

The stability and dynamic performance of the system are impacted by the uncertainties present in the converter model and controller parameters. This paper introduces a robust non-fragile control approach that addresses the influence of these uncertainties. The approach involves developing a control law that achieves quadratic stabilization of the closed-loop system while also satisfying the H∞ norm constraint for disturbance attenuation. Based on this concept, a robust non-fragile PI controller is designed explicitly for voltage mode control of a dc–dc buck converter. The effectiveness of the proposed control technique is evaluated from two perspectives: (i) its ability to withstand significant perturbations in plant parameters and load disturbances and (ii) its resilience in the presence of variations in controller parameters. The effectiveness of the proposed control scheme is validated using simulation and experimental results. [ABSTRACT FROM AUTHOR]

A novel pulse width modulation (PWM) overmodulation technique based on splitting variable modulating waveform is proposed in this paper. It aims to solve the disadvantages of complex and difficult application of the existing space vector pulse width modulation (SVPWM) overmodulation algorithm and offer a simpler implementation for overmodulation than classic SVPWM techniques. When the modulation index M is within the linear modulation range [0, 1], the modulating waveform is a sinusoidal wave. With the M is increasing within [1, 4/π], the modulating waveform area expands continuously until it becomes a square wave. The PWM output voltage of the vector control system is implemented by using triangle carrier-based sampling pulse width modulation. Furthermore, digital low-pass filters are used in the d-axis current and q-axis voltage of the system, in order to eliminate the negative influence of the PWM low-order harmonics on the proportion integration control in the overmodulation range. The control software is modified and improved to overcome the shortage of slow response speed. The basic logic of the software is to close the filtering process once the load or speed instructions changes and turn on the filtering process when the transient process ends. The contradiction between the filtering and dynamic responses is thus eliminated by using the basic logic. Compared with the SVPWM working in linear region, the constant torque speed regulating range of the AC motor has an improvement of 10% based on the proposed technique. Simulated and experimental results indicate the good effectiveness and feasibility of this technique. [ABSTRACT FROM AUTHOR]

A novel state estimation methodology is proposed in this paper for microgrids monitoring using synchronized and non-synchronized measurements. A Kalman filter model is proposed to track both system states and frequency along the time considering the measurements gathered from the grid by PMUs and smart meters allocated in the system. An augmented measurement Jacobian matrix is formed considering system states and frequency as variables to be estimated along the time. Distributed generation is connected to the grid by voltage source inverters (VSI) considering frequency and voltage droop control characteristics. A radial 18-bus test system is used for the computational simulations in order to prove the efficiency of the proposed methodology. The algorithm is tested considering microgrid in grid-connected and islanded operation modes providing satisfactory results with reduced estimation errors when compared to the RSCAD (Real-Time Simulation Software Package) software. The main contributions of this work include: (i) the explicit model of frequency and voltage droop control of VSI in a Kalman filter model; (ii) the capability of tracking microgrids frequency and system states along the time; (iii) the explicit model of derivatives of phasor measurement units and smart meters measurements with respect to the system states and frequency. [ABSTRACT FROM AUTHOR]

In this paper, a high efficiency implementation of constant voltage (CV) control of wireless charging system with LC/S compensation is proposed for stationary electrical vehicles. The LC/S compensation network is designed based on constant current (CC) design procedure with zero phase angle (ZPA). In the receiver side, semi-bridgeless rectifier (SBR) and pulse density modulation (PDM) control are both implemented to provide CV output without wireless communication devices. With the use of SBR topology and the implementation of the PDM control strategy for SBR switches, the soft-switching operation of SBR switches is also provided. Thus, the efficiency of the CV control mode is improved in a wide range of load. The experimental results of a 1.05 kW prototype are provided to demonstrate the effectiveness of the proposed system. The peak efficiency of the system is obtained 91.9% at full load condition. In experiment, the performance comparison of PDM control with phase-shift (PS) control method is also carried out for the proposed wireless charging system. The overall efficiency of the system with PDM control is significantly improved compared to PS control at light load conditions. [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]

A design procedure for an RLC damping branch applied at a voltage source inverter followed by an LCL output filter is carried out in this paper. The main purpose of the proposed methodology is to allow the system to operate properly in both grid-connected (GC) and islanded (IS) modes with smooth transitions between them. The usage of passive damping methods to smooth the resonating filters effects is well known. However, the design procedure of the damping branch is specific for either the GC or IS mode, and usually, the parameters tuned for an operation mode are unsuitable for the other one. Thereby, this paper contributes to presenting a methodology design of an RLC branch aimed to achieve damping effect for both operation modes, thus allowing the continuous operation with no hazardous transients during transitions. By means of the proposed approach, the passive elements are adequately designed in order to provide easy controller synthesis. Therefore, a two-loop control strategy is adopted where the inner loop controls the capacitor voltage and ensures the system stability for both operation modes; meanwhile, an additional outer loop controls the grid current for GC mode allowing active and reactive power flows. Experimental results for a 2-kW prototype are presented in order to validate the proposed design methodology and control strategy. [ABSTRACT FROM AUTHOR]

A low-noise amplifier (LNA) topology with tunable input matching and noise cancellation is introduced and described in this paper, which was designed and optimized to interface with a magnetoelectric (ME) antenna in a 0.35 µm MEMS-compatible CMOS process. Compared to conventional antennas, acoustically actuated ME antennas have significantly smaller area for ease of integration. The LNA was simulated with an ME antenna model that was constructed based on antenna measurements. Input matching at the LNA-antenna interface is controlled with a circuit that varies the effective impedance of the gate inductor using a control voltage. Tunability of 455 MHz around 2.4 GHz is achieved for the optimum S11 frequency with a control voltage range of 0.3–1.2 V. The proposed LNA has a noise cancelling feedback loop that improves the noise figure by 4.1 dB. The post-layout simulation results of the LNA show a 1-dB compression point of – 7.4 dBm with an S21 of 17.8 dB. [ABSTRACT FROM AUTHOR]

To improve the resistive switching performance of RRAM devices, it is desirable to find electrodes with good ability of oxygen reservoir. In this paper, bipolar switching mode of TiN/SiO2/FePt devices is achieved by using FePt as oxygen reservoir, since O atoms will be absorbed by Fe atoms to form FeOx film. Therefore, the oxygen reservoir's ability can be evaluated by the molar ratio of FeOx in FePt film and it is found that the more molar ratio of FeOx the stronger oxygen reservoir's ability is obtained. Interestingly, the self-rectifying characteristics in the devices with FePt electrode is observed due to the different work functions between TiN (4.7 eV) and FePt (> 5 eV). Furthermore, the transition between self-rectifying mode and diode mode can be achieved by controlling the applied voltage, which is beneficial for 1D1R architecture. The study in this paper may offer a method for fabrication of oxide-RRAM based 3D crossbar array with good performances. [ABSTRACT FROM AUTHOR]

This paper describes how to use particle swarm optimization to implement a neural network-based admittance estimation strategy for controlling a dynamic voltage restorer (DVR) with optimized controller gains (PSO). To improve DVR efficiency, robustness, and tracking capability, a control strategy based on source admittance components is used to determine fundamental admittance components from distorted supply voltages. Because of the algorithm's simple formulas, estimating conductance and susceptibility from load currents is quick. To minimize the gains of proportional integral controllers, particle swarm optimization (PSO) is used. This improves dynamic response, tracking capability, as well as transient and steady-state stability. When consumer loads change on a regular or irregular basis, this algorithm is very effective. The admittance control strategy for DVR is modeled and simulated using MATLAB/Simulink and implemented using hardware setup d-SPACE made MicroLab box DS1202/DS1302 for mitigating harmonics and voltage sag/swell (2 GHz dual-core real-time processor and user-programmable FPGA). The suggested DVR's test results were satisfactory under both balanced and unbalanced load conditions. [ABSTRACT FROM AUTHOR]

Three-phase grid-connected voltage-source inverters (VSIs) are widely used for renewable energies integration. Cost reduction and suitable operation under nonideal grid conditions are their important technical challenges. Accordingly, this paper proposes an efficient adaptive neural filter-based virtual flux (ANF-VF) estimator for sensorless control of a grid-connected VSI under unbalanced and distorted grid conditions. To perform sensorless predictive direct power control (PDPC), the grid voltage sensors are substituted by the ANF-VF estimator. This estimator includes an emulated ideal integrator in series with two simple ANFs. Lyapunov's theory-based convergence analysis is conducted for its optimal tuning. This is resulted in an accurate extraction of VF fundamental components. For more effectiveness under unbalanced grid conditions, an extension of original instantaneous power theory is introduced in the proposed VF-based PDPC (VF-PDPC). Effectiveness of the VF-PDPC is verified through simulation and experimental tests. A direct and smooth startup without initialization is accomplished under unbalanced grid conditions. Superiority of the VF-PDPC compared to the conventional PDPC is demonstrated. The proposal presents sinusoidal grid currents with low total harmonic distortion under unbalanced and distorted grid conditions. Moreover, the ANF-VF estimator illustrates best performances compared to the second-order generalized integrator-based VF estimator that uses measured grid voltages under nonideal grid conditions. [ABSTRACT FROM AUTHOR]

The paper deals with the accomplishment of a FPGA-based dynamic model of a three-phase Vienna rectifier controlled in order to feature unity power factor operations. Such a model has been developed for the Hardware In the Loop (HIL) implementation of a test rig in which the power converter is replaced with an embedded system using a FPGA board. The proposed approach has been fostered mainly to test different converter control algorithms in a fast and safe way. Such solution is based on a software platform environment with a high-level abstraction that ensures a good trade-off between accuracy and hardware resources, also allowing a fast prototyping procedure. The results obtained by the HIL implementation have been compared with those of a fully hardware experimental rig, confirming a very good agreement in terms of accuracy and dynamic behavior. [ABSTRACT FROM AUTHOR]

The basic prerequisites for the correct operation of the classic on-load tap-changing voltage control (CVC) are that the distribution network (DN) is passive. However, by installing distributed generators (DGs), today's DNs become increasingly active. Consequently, by measuring only the current and voltage magnitudes at the on-load tap-changing transformer secondary side, its automatic voltage regulator receives a false image of the DN load. In such a case, it is impossible to determine the optimal voltage value at the transformer secondary side in all possible states. Therefore, the CVC must be adapted to the new situation. This paper presents a simple, efficient, and inexpensive adaptive on-load tap-changing voltage control (AVC) for active DN with DGs and customers placed on different feeders. The adaptation refers only to the false image of DN load correction, based on the DN load assessment without the influence of DG. Practically, this correction is realized by minimal investment into the existing equipment and infrastructure. Thus, complicated methods requiring an expensive upgrade of DN in terms of communication infrastructure expansion, installation of new sensors and control devices, their coordination, and integration with modern IT/OT systems are avoided. The verification of the AVC is performed in real-life in the real-world active DN. [ABSTRACT FROM AUTHOR]

Coordinated voltage control CVC is necessary in microgrid with high penetration of distributed renewable energy resources, to keep the voltage in required range and to optimize the grid performance. The SCADA-as-a-service (SCADA-aaS) approach allows the secured deployment of CVC and provides the interoperability framework for the network operators to distribute their CVC algorithm to remote microgrid or to implement a third-party CVC. This paper presents the first real-world implementation of CVC algorithm deployment via SCADA-aaS. This real-world implementation demonstrates the feasibility of the SCADA-aaS approach. Experiences and lessons learned from the implementation are discussed. [ABSTRACT FROM AUTHOR]

The modeling and control of a stand-alone solar photovoltaic with battery backup-based hybrid system is implemented in this paper. Normally, a hybrid PV system needs a complex control scheme to handle different modes of operations. Mostly, a supervisory control is necessary to supervise the change in controller arrangement depending on the applied mode. The proposed system consists of a dc–dc boost converter, a single-phase inverter and a bidirectional dc–dc converter. The PV array is interfaced through a dc–dc boost converter and is controlled with the help of an MPPT controller to extract the maximum power. The battery backup unit is integrated with the PV system through a common dc bus for the power management within the system as well as to maintain a constant dc bus voltage. The power exchange between the battery and dc bus can be controlled by a bidirectional buck–boost converter. The system can be operated with or without battery units, having no alteration of the control configuration, as a result use of complex supervisory controller can be avoided. For simple circuit architecture to be realizable, a control scheme based on sliding mode control is designed for the full-bridge inverter. Its purpose is to maintain a sinusoidal output voltage with small steady-state error, lower total harmonic distortion (THD) and excellent dynamic response under step change in load. Finally, the simulation results from a two-stage 2 kW, 110 V, single-phase stand-alone PV system are provided to confirm the theoretical analysis, effectiveness and feasibility of the proposed control scheme. [ABSTRACT FROM AUTHOR]

To address the problem of insufficient system inertia and improve the power quality of grid-connected inverters, and to enhance the stability of the power system, a method to control a virtual synchronous generator (VSG) output voltage based on model predictive control (MPC) is proposed. Parameters of the inductors, capacitors and other components of the VSG can vary as the temperature and current changes. Consequently the VSG output voltage and power control accuracy using the conventional MPC method may be reduced. In this paper, to improve the parameter robustness of the MPC method, a new weighted predictive capacitor voltage control method is proposed. Through detailed theoretical analysis, the principle of the proposed method to reduce the influence of parameter errors on voltage tracking accuracy is analyzed. Finally, the effectiveness and feasibility of the proposed method are verified by experimental tests using the Typhoon control hardware-in-the-loop experimental platform. [ABSTRACT FROM AUTHOR]

This paper proposes a nonuniform delay-dependent robust secondary voltage control strategy with a finite-time voltage reference observer for an islanded microgrid. A discrete-time consensus algorithm is introduced to track the output voltage. By model transformation, a closed-loop microgrid control system is obtained. And then, the corresponding global stability and robust performance analysis theorems are derived. After implementing a series of trial studies, the impacts of secondary voltage control gains, sampling time on energy-to-peak robust performance are obtained. And the feasible optimal voltage control gains can be derived. Besides, a distributed cooperative secondary frequency control is introduced. Simulations of a four inverter-based microgrid test system are presented to verify the control performance. The simulation results indicate that our proposed method can maintain accurate voltage/frequency restoration and active power sharing. In addition, the voltage control gain parameters, arbitrary nonuniform time delays, and especially sampling time effects on the secondary voltage control performance are also verified. [ABSTRACT FROM AUTHOR]

This paper describes a symmetric phase frequency detector (PFD). The symmetric structure of PFD provides phase-locked loop (PLL) functions with a low jitter. The most important point in designing PFDs is attention to their dead zone, the extent of their linearity, and the frequency range of operation. As the dead zone of a phase detector circuit is smaller, this circuit is capable of detecting fewer phase differences in high frequencies. In this paper, considering the trade-off between the dead zone and the maximum operating frequency, the highest operating frequency is achieved with minimal dead zone design. Post-layout simulation for TSMC 0.13 μm technology is performed using the CMOS technology: The results so obtained are then compared with existing literature. These results indicate a power consumption of less than 90 μW and a frequency response of 4.1 GHz, as well as a dead zone of less than 25 ps in the worst case: This is a suitable condition as compared to previous, related works. The area of the proposed symmetric circuit is 250 μm2. Finally, the proposed PFD tested in PLL and the results indicate that the structure is useful for frequency synthesizer applications. [ABSTRACT FROM AUTHOR]

In this paper, a new pseudo-exponential function is described and a new CMOS exponential-control variable gain amplifier (VGA) based on the new function is introduced. No multiplier is needed in the proposed approach. The VGA operates in current mode and includes two different stages. The first stage is a simple current amplifier while the second stage is an attenuator. The overall behavior of the stages gives the new pseudo-exponential function. The VGA circuit has been designed and simulated for a 0.18 μ CMOS process. Post layout results show that the circuit has a bandwidth of 164 MHz and a gain range of 32.5 dB between − 21 and + 11.5 dB. [ABSTRACT FROM AUTHOR]

This paper proposes a novel Z-source boost derived hybrid converter (ZSBDHC) that produces high gain dual output from a single DC input, which is the choice of a solar photovoltaic system. This has multiple advantages as lesser count of switches, high power processing capability and high reliability result in reduction of overall cost. Besides, the prime advantage of this topology is achieving high voltage gain for a low duty ratio. The system transfer function is derived and the stability of the system is studied with the aid of average state model of the converter under continuous conduction mode. The transfer function of the system exhibits the sixth order dynamic characteristics, which is reduced to second order approximation to design the control parameters and to develop the closed loop scheme. To prove the robustness of the ZSBDHC with voltage feedback control, it is examined with line, load regulation and set point variation. Computer simulation is done for the dynamic characteristics of the ZSBDHC. The experimental operation is also demonstrated to validate the simulated results. [ABSTRACT FROM AUTHOR]

Sensorless strategies become very popular in modern control techniques because they increase the system reliability. Besides, they can be used as back-up control in case of sensor failure. In this paper, a DC-link sensorless control approach is developed, which is suited for grid-connected PV systems. The studied system is a two-stage PV scheme, where the DC–DC stage (boost converter) is controlled using an adaptive step-size perturb and observe (P&O) method. Further, the inverter control is accomplished by voltage oriented control (VOC). Generally, the VOC is implemented with two cascaded control loops, namely an outer voltage loop and an inner current loop. However, in this work, the outer loop is avoided and the reference current is generated using a losses model for the system. The losses model accounts for the most significant losses in the PV system. Moreover, particle swarm optimization (PSO) is utilized to compensate for the unmodeled losses. The PSO is executed offline for the purpose of calculation burden reduction. The proposed approach simplifies the cascaded VOC strategy and eliminates the DC-link voltage sensor, which in turn decreases the cost of the system. Finally, the proposed technique is compared with the conventional one at different atmospheric conditions and validated using MATLAB simulation results. [ABSTRACT FROM AUTHOR]

Encouraged by the increasing electric energy consumption, the distributed generation has been widely included in the electrical power system. However, renewable energy resources have intermittent characteristics. When the distributed generation is high at certain times of the day, the energy generation at distribution systems can become higher than the required power. The surplus energy is returned to the transmission system, giving rise to active distribution networks. This paper proposes an approach to optimally managing the existing distributed generation and voltage control devices. The management is performed by solving an optimal power flow problem, aiming to find an operating condition for the system in which the losses are minimized, and the voltage profiles are improved. A combined transmission and distribution system is proposed. Some scenarios are considered to assess the impact of distributed generation insertion and the contribution of these sources in support of reactive power. The results indicate the need for adequate active distribution networks management, which depends on the distribution generation insertion level and the generation sources' power factor. [ABSTRACT FROM AUTHOR]

This paper presents and validates a novel approach to designing an active controller for a small-scale experimental structure subjected to the action of multiple moving loads. Many of the numerically validated active control methods presented in the literature assume that the synthesised control solution can be applied directly to the structure. When a real structure is investigated, the closed-loop stability and performance of the system are affected by the actuators' dynamics and by the signal-to-noise ratio. In some cases when the structure is complex, the model used for the structure can have controllability and observability problems. In this study, an active control solution is designed using a simplified model, and then, it is experimentally validated. The control voltage dependent on the measured displacement signals is fed back to the structure via electrodynamic actuators. The objective of the control is to reduce the structure's deflection under the action of the loads at sensors' locations. Numerical and experimental results prove that using linear or cubic displacement feedback control the vibration amplitudes can be significantly reduced. The controller can tolerate speed variations, but it always needs to include compensation in order to increase the stability margins of the controlled system. The linear displacement feedback has a better performance at low values of the deflection, whereas the cubic displacement feedback shows a better robustness performance at high values of moving masses and speed variations. [ABSTRACT FROM AUTHOR]

Recently, the Secondary Voltage Regulation (SVR) is installed in some power systems in order to ensure the coordination voltage control devices. In other hand, the shunt FACTS devices such as the Static Var Compensator (SVC) and the STATic COMpensator (STATCOM) are extensively used for the local voltage control without any coordination with other voltage control devices, without any reciprocal coordination. In this paper, new models of SVC and STATCOM are proposed to be adopted in power flow models that include the SVR. The proposed models are implemented and tested on a model of the Italian power system. Furthermore, a new method based on sensitivity analysis is proposed to find the most sensitive placements for the installation of SVC and STATCOM. The results obtained show the highly computational performance of the propose models and also the effectiveness of the sensitivity analysis to find the best placements of SVC and STATCOM taking into account the SVR. [ABSTRACT FROM AUTHOR]

Shunt active power filters (SAPFs) have been widely used to improve power quality of the grid by mitigating harmonics injected from nonlinear loads. This paper presents a new method for improving the performance of SAPFs using neutral-point-clamped (NPC) three-level inverters. NPC three-level inverters often suffer excessive voltage fluctuations at the neutral-point of DC-link capacitors, which may damage switching devices and cause additional high harmonic distortion of the output voltage. In order to solve the problem, two compensating schemes are proposed to restrict voltage fluctuation in the inverters. The first is voltage dependent, adopting a voltage compensation method, while the second is current dependent, using a current compensation method. The paper describes the respective circuit architectures and principles of operation. Corresponding models are mathematically formulated and evaluated under typical balanced and unbalanced working load conditions. The results show that both schemes are able to alleviate considerably voltage oscillations and hence harmonic distortions, and the current-compensated NPC inverter outperforms the voltage-compensated NPC inverter. Consequently, it is shown that the proposed approaches are effective and feasible for improving power quality of the grid when connected to nonlinear loads. [ABSTRACT FROM AUTHOR]

The InAs/GaSb superlattice infrared detector has been developed with tremendous effort. However, the performance of it, especially long-wavelength infrared detectors (LWIR), is still limited by the electrical performance and optical quantum efficiency (QE). Forcing the active region to be p-type through proper doping can highly improve QE, and the gating technique can be employed to greatly enhance electrical performance. However, the saturation bias voltage is too high. Reducing the saturation bias voltage has broad prospects for the future application of gate voltage control devices. In this paper, we report that the gated P+–π–M–N+ InAs/GaSb superlattice long-wavelength infrared detectors exhibit different π region doping levels that have a reduced minimum saturation bias at − 10 V with a 200-nm SiO2 layer after a simple and effective anodic vulcanization pretreatment. The saturation gate bias voltage is much lower than − 40 V that reported with the same thickness of a 200-nm SiO2 passivation layer and similar structure. The optical and electrical characterization indicates that the electrical and optical performance of the device would be weakened by excessive doping concentration. At 77 K, the 50% cutoff wavelength of the device is about 8 µm, the 100% cutoff wavelength is 10 µm, the maximum quantum efficiency is 62.4%, the maximum of responsivity is 2.26 A/W at 5 µm, and the maximum RA of the device is 1259.4 Ω cm2. Besides, the specific detectivity of Be 780 °C-doped detector without gate electrode exhibits a peak of 5.6 × 1010 cm Hz1/2/W at 5 µm with a 70-mv reverse bias voltage, which is more than three times that of Be 820 °C-doped detector. Moreover, the peak specific detectivity could be further increased to 1.3 × 1011 cm Hz1/2/W at 5 µm with a 10-mv reserve bias voltage that has the bias of − 10 V at the gate electrode. [ABSTRACT FROM AUTHOR]

This paper proposes a three-level buck converter utilizing a Digital-to-Analog Converter (DAC)-based flying capacitor voltage control technique, which controls the voltage on a flying capacitor with a differential difference amplifier and common mode feedback circuit for stable operation. Employment of the DAC-based flying capacitor voltage control circuit allows the proposed circuit to compensate for the inductor voltage error as the load current varies. The proposed three-level buck converter was implemented with a CMOS 180 nm standard process. The measurement results demonstrate the wide range of the input and output voltage from 2.7 V to 3.6 V and 0.7 V to 2.4 V, respectively. The proposed three-level buck converter achieved the peak power efficiency of 91% and output ripple voltage of 32.5 mV at the switching frequency of 2 MHz and load current range of 10 mA to 400 mA. [ABSTRACT FROM AUTHOR]

In the weak current network environment, the existence of power network impedance will reduce the current control stability margin of LCL grid connected inverter, the stability margin will gradually deteriorate as the inductive component of the power network impedance increases, leading to system instability. In this paper, an improved weighted average current control strategy is proposed, which is based on the active damping control of the voltage feedforward of the charged network. In the new control strategy, with the zero-pole cancellation method, a new weighting coefficient related only to the parameters of LCL filter is obtained, which reduces the order of the system, suppresses the influence of power network impedance, and improves the stabilization of the system, getting better inverter output current quality. Then the influence of power network impedance on the control system of grid connected inverter is analyzed, and the feed-forward control of grid voltage is improved to improve the stability of inverter in weak current network. The Bode diagram analysis and MATLAB simulation results proved that the proposed control strategy is feasible. [ABSTRACT FROM AUTHOR]

In this paper, a method to control the harmonic content of the magnetic flux density in the airgap of a synchronous machine is presented. Voltage harmonics in one phase as well as the exciting magnetic forces can be affected. Switched power electronics were used to provide the field current to a synchronous machine, the control added specific current harmonics to the DC field current in order to minimize either voltage harmonics or magnetic forces. The method is verified and compared with simulations and experiments on an existing electrical machine. [ABSTRACT FROM AUTHOR]

This paper describes a high performance voltage differencing inverting buffered amplifier (VDIBA). The transconductance of the proposed circuit is enhanced by using positive feedback technique with only two extra transistors used in active load. Moreover, the bandwidth of proposed circuit is enhanced by using resistive compensation technique. The performance of proposed VDIBA is demonstrated by detailed frequency analysis. Furthermore, it is shown that the transconductance can be enhanced up to 4.61 mS at biasing current of 300 µA. In addition, a third order low pass filter is given as an application example to confirm the high performance of the proposed VDIBA. The proposed low pass filter operates at natural pole frequency of 15 MHz. The proposed VDIBA and its filter application are implemented using TSMC 90 nm CMOS technology in Cadence virtuoso schematic composer at ±0.6 V supply voltage. [ABSTRACT FROM AUTHOR]

This paper investigates an adaptive combined control strategy for single-phase cascaded H-bridge multilevel converter under distorted load conditions. The nonlinear loads cause harmonic distortion and affect the quality of output voltage. An adaptive voltage control strategy is suggested to compensate for the harmonic distortion caused by the nonlinear loads. The suggested control strategy enables the output voltage to track the reference according to the load-side disturbances. The DC links of the multilevel converter generate low-frequency ripples which also cause output voltage distortion under nonlinear load conditions. To compensate this, an adaptive DC link ripple control strategy is also suggested. Detailed analysis has been conducted to verify the effectiveness of the suggested system and is compared to the conventional control strategies. Fast dynamic response and lower distortion in output voltage are obtained with the suggested strategy compared to the conventional control strategies. Experimental and simulation results are provided to validate the suggested control scheme. [ABSTRACT FROM AUTHOR]

The increasing participation of wind turbines based on doubly fed induction generator (DFIG) in the power system around the world is motivating the investigation of novel strategies to enhance the reliability of DFIG and power system connection. This paper proposes the use of a new hybrid multilevel back-to-back converter on DFIG wind turbine to improve its fault ride-through capability and power system transient stability. The proposed topology is built adding single-phase full-bridge inverters in series with each phase of traditional three-phase inverter. This converter is able to generate higher voltages in rotor circuit whenever it is required, which can effectively protect power converter and at the same time contribute with grid transient performance. Simulation results, using PSCAD®, are presented for a 2 MW DFIG machine submitted to symmetrical faults in single machine—infinite bus and three-bus system. Results show that the proposal is effective as a protection and works well as an alternative to traditional solutions, limiting currents and maintaining power control during voltage dips. It is also effective in contribution with the improvement of transient stability margin by the possibility of reactive power injection. [ABSTRACT FROM AUTHOR]