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• Readers of Serbian are fluent in two alphabets, Roman and Cyrillic. • This alphabet analogue of bilingualism reveals how linguistic codes interact. • The interference that arises between alphabetic codes is phonological in nature. • Local and global control constrain parallel activation of alphabetic codes in bialphabetism. • Some constraints are dynamic and others stable during an experimental session. We investigated language control in (within-language) between alphabet switching during comprehension by exploiting the overlap between the two character sets of Serbian. We compared recognition latencies to phonologically ambiguous and phonologically unambiguous versions of the same word (PAE – Phonological Ambiguity Effect) to obtain an index of interference between the two alphabets. Evidence for transient control arose from changing alphabets between trials within a block and the larger PAE when the alphabet of the target changed from the previous trial. Evidence for sustained control arose from presenting a single-alphabet block prior to a mixed alphabet block and the larger PAE when the target alphabet differed from the alphabet of the preceding single-alphabet block. We conclude that within-language alphabet switching exhibits effects of transient and global language control during comprehension. However, switching effects (and their temporal dynamics) were evident only when recognition was challenged by the presence of phonologically ambiguous word forms. [ABSTRACT FROM AUTHOR]

The civil aviation sector plays an increasingly significant role in transportation sustainability in the environmental, economic, and social dimensions. Driven by the concerns of sustainability in the aviation sector, more electrified aircraft propulsion technologies have emerged and form a very promising approach to future sustainable and decarbonized aviation. This review paper aims to provide a comprehensive and broad-scope survey of the recent progress and development trends in sustainable aviation electrification. Firstly, the architectures of electrified aircraft propulsion are presented with a detailed analysis of the benefits, challenges, and studies/applications to date. Then, the challenges and technical barriers of electrified aircraft propulsion control system design are discussed, followed by a summary of the control methods frequently used in aircraft propulsion systems. Next, the mainstream energy management strategies are investigated and further utilized to minimize the block fuel burn, emissions, and economic cost. Finally, an overview of the development trends of aviation electrification is provided. [ABSTRACT FROM AUTHOR]

To solve the problem of transient control design with uncertainties and degradation in the life cycle, a design method for a turbofan engine's transient controller based on reinforcement learning is proposed. The method adopts an actor–critic framework and deep deterministic policy gradient (DDPG) algorithm with the ability to train an agent with continuous action policy for the continuous and violent turbofan engine state change. Combined with a symmetrical acceleration and deceleration transient control plan, a reward function with the aim of servo tracking is proposed. Simulations under different conditions were carried out with a controller designed via the proposed method. The simulation results show that during the acceleration process of the engine from idle to an intermediate state, the controlled variables have no overshoot, and the settling time does not exceed 3.8 s. During the deceleration process of the engine from an intermediate state to idle, the corrected speed of high-pressure rotor has no overshoot, the corrected-speed overshoot of the low-pressure rotor does not exceed 1.5%, and the settling time does not exceed 3.3 s. A system with the designed transient controller can maintain the performance when uncertainties and degradation are considered. [ABSTRACT FROM AUTHOR]

The increasing photovoltaic (PV) installations and their integration with the utilities have complexed the operation of the power system network making them vulnerable to various faults and abnormalities. The traditional methods developed to handle this problem are aimed to explore the ability of PV inverter to operate in standalone (SA) mode when there are predictable grid side abnormalities or scheduled maintenances. In this article, a grid condition monitoring based transition control approach is developed using machine learning algorithm and a hybrid control strategy. This article is motivated at handling the intentional and unintentional islanding conditions by operating the PV system in both grid-connected (GC) and SA modes. The switching between the controllers is performed by the central controller ensuring a smooth transition and continuous power delivery to the load. For validating the claims, numerical simulations and experimental analysis are carried out with a 4 kWp GC PV system. The results depicted fast grid condition monitoring under 20 ms and smooth transition without any transients or harmonics. [ABSTRACT FROM AUTHOR]

This research addresses distributed proportional power-sharing of inverter-based distributed generators (DGs) in microgrids under variations in the maximum power capacity of DGs. A microgrid can include renewable energy resources such as wind turbines, solar panels, fuel cells, etc. The intermittent nature of such energy resources causes variations in their maximum power capacities. Since DGs in microgrids can be regarded as multiagent-systems (MASs), a consensus algorithm is designed to have the DGs to generate their output power in proportion to their maximum capacities under capacity fluctuations. A change in power capacity of a DG triggers the consensus algorithm, which uses a communication map at the cyber layer to estimate the corresponding change. The convergence rate of the algorithm is analytically established and bounds on allowable capacity fluctuations are derived based on practical constraints. During the transient time of reaching a consensus, the delivered power may not match the load power demand. To eliminate this mismatch, a control law is augmented that consists of a finite-time consensus algorithm embedded within the overarching power-sharing consensus algorithm. The effectiveness of the distributed controller is assessed through simulation of a microgrid consisting of a realistic model of inverter-based DGs. Details of the microgrid model, its controller structures, and a comprehensive list of parameters are provided. [ABSTRACT FROM AUTHOR]

Machine learning related research in transient control has drawn considerable attention with the rapid increase in data measurement from power grids. Two key components, the control algorithm and system structure, work together to determine the control performance. The design of control laws, the selection of phase measurement units, the allocation of power resources, and the scheduling of communication topology in limited cyber-physical resources need to be considered. Many existing scheduling or planning schemes specialized for control structure are designed based on various linearized analytical models or the optimization of steady states. However, the transient dynamics of power grids are nonlinear and parts of these dynamics are usually unknown. Linearized analytical models cannot represent the transient dynamics of power grids with large disturbances. This article proposes a sparse neural network based reinforcement learning scheme to optimize the control system structure for the transient stability enhancement of power grids with energy storage systems. One adjustable group sparse weight matrix is introduced to formulate both control structure and actor–critic networks. This strategy enables the proposed scheme to simultaneously schedule the control system structure and design the control laws by online learning without solving any combinational optimization problems or requiring any linearized analytical models. The sufficient conditions of learning stability, control stability, and group sparsity are thoroughly studied by mathematical analysis. The proposed scheme is simulated on an IEEE 118-bus test system for verification. The simulation results confirm the feasibility, advantages, and adaptability of the proposed method. [ABSTRACT FROM AUTHOR]

Transient dc bias current will appear in dual-active-bridge (DAB) dc–dc converter when power changes, resulting in transformer core saturation. Traditionally, a transitional period with extra calculation is added in the transient process to keep the voltage-second balance and eliminate the dc bias current for the DAB converter. In this article, the modulation process rather than the phase-shift control is concerned, and the transient dc bias current can be reduced or even eliminated by staggering the load time of the primary bridge and secondary bridge compare values. The modulation scheme with this modification does not need any transitional period or extra calculation, and the time delay in the closed-loop control is constant and smaller than the previous schemes. Besides, as only the load time is modified, the modulation scheme can be implemented in all the phase-shift control methods and the whole operation range. The experimental results verify the theoretical analysis and show the practical feasibility of the modified modulation schemes. [ABSTRACT FROM AUTHOR]

The afterburning phase of an aero gas turbine engine is essential for boosting engine thrust. Traditional methods that combine open-loop afterburner fuel flow with closed-loop nozzle throat area control always degrade control quality during the transients of afterburner activation and deactivation. This results in fluctuations in the turbine outlet total pressure, consequently decreasing the fan surge margin, and may even lead to afterburner ignition failure or fan surge. A model-based deduction learning control method is proposed to address these issues. This method comprises: 1) a model-based offline experience deduction and learning module to enhance the coordination of afterburner fuel flow and nozzle throat area control during the early stages of afterburner activation or deactivation; 2) a power lever angle reference trajectory module designed to enhance the linearity of thrust output; 3) a nonlinear integrated online output module to maintain control stability. Simulation results have shown that the method effectively reduces the fluctuations in turbine outlet total pressure, bolsters the fan surge margin, and improves the linearity of thrust during the afterburning phase. • The proposed method can enhance afterburner transient control quality. • A throttle reference trajectory module has improved the thrust's linearity. • Both individual engine test and full envelope test verification are conducted. [ABSTRACT FROM AUTHOR]

This paper proposes a coordinated control of doubly fed induction generator (DFIG)-based wind farms' (WFs) post-fault active power and synchronous generators' (SGs) tripping with the aim of improving transient stability of both the first swing and multi swings. To achieve it, the impact mechanism of the WFs' post-fault active power and SGs' tripping on the stability margin of each swing is first presented by using extended equal area criterion (EEAC). Based on this, a principle of the coordinated control is put forward. The WFs' control period is designed as six stages, and the value of post-fault active power in each stage is suggested to improve the stability of the first five swings and maintain the post-fault steady state. To decrease the tripping amount of the SGs, the SGs are tripped only when WFs' control effect is not sufficient to avoid the instability. Then, by utilizing an “online pre-decision and real-time matching”scheme, an engineering application method for the control principle is proposed, where the control procedures and detailed parameters calculation are demonstrated. The numerical simulations show that the coordinated control has a better damping effect and a less control cost (less amount of tripped SGs) than the traditional DFIG control or traditional SG tripping.

Highlights • A simulation tool for dynamic modelling and transient control of adiabatic CAES is presented. • The structure of the simulation tool with a developed component library is introduced. • Multi-physical models covers pneumatics, thermodynamics, turbomachinery and electrics. • Case studies show its merits, e.g., performance analysis, dynamic control and grid applications. Abstract The field of large-scale electrical energy storage is growing rapidly in both academia and industry, which has driven a fast increase in the research and development on adiabatic compressed air energy storage. The significant challenge of adiabatic compressed air energy storage with its thermal energy storage is in the complexity of the system dynamic characteristics arising from the multi-physical (pneumatic, thermal, mechanical and electrical) processes. This has led to a strong demand for simulation software tools specifically for dynamic modelling and transient control of relevant multi-scale components, subsystems and whole systems with different configurations. The paper presents a feasibility study of a simulation tool development implemented by the University of Warwick Engineering team to achieve this purpose. The developed tool includes a range of validated simulation models from the fields of pneumatics, thermodynamics, heat transfer, electrical machines and power grids. The structure of the developed tool is introduced and a component library is built up on the Matlab/Simulink platform. The mathematical descriptions of key components are presented, which precedes a presentation of four case studies of different applications. The case studies demonstrate that the simulation software tool can be used for dynamic modelling of multi-scale adiabatic compressed air energy storage components and systems, real performance analysis, dynamic control strategy implementation and feasibility studies of applications of adiabatic compressed air energy storage integrated with power grids. The paper concludes that the continued development and use of such a tool is both feasible and valuable. [ABSTRACT FROM AUTHOR]

Understanding the neurophysiological signals underlying voluntary motor control and decoding them for controlling limb prostheses is one of the major challenges in applied neuroscience and rehabilitation engineering. While pattern recognition of continuous myoelectric (EMG) signals is arguably the most investigated approach for hand prosthesis control, its underlying assumption is poorly supported, i.e., that repeated muscular contractions produce consistent patterns of steady-state EMGs. In fact, it still remains to be shown that pattern recognition-based controllers allow natural control over multiple grasps in hand prosthesis outside well-controlled laboratory settings. Here, we propose an approach that relies on decoding the intended grasp from forearm EMG recordings associated with the onset of muscle contraction as opposed to the steady-state signals. Eight unimpaired individuals and two hand amputees performed four grasping movements with a variety of arm postures while EMG recordings subsequently processed to mimic signals picked up by conventional myoelectric sensors were obtained from their forearms and residual limbs, respectively. Off-line data analyses demonstrated the feasibility of the approach also with respect to the limb position effect. The sampling frequency and length of the classified EMG window that off-line resulted in optimal performance were applied to a controller of a research prosthesis worn by one hand amputee and proved functional in real-time when operated under realistic working conditions. [ABSTRACT FROM AUTHOR]

The modern diesel engines equip the exhaust gas recirculation (EGR) system to suppress the NOx emissions. In addition, the variable geometric turbocharger (VGT) system is installed to improve the drivability and fuel efficiency. These EGR and VGT systems have cross-coupled behavior because they interact with the intake and the exhaust manifolds. Furthermore, the turbocharger time delay, gas flow dynamics through EGR pipe cause the nonlinearity characteristics. These nonlinear multi-input-multi-output characteristics cause the degradation of control accuracy, especially during the transient condition. In order to improve the control accuracy, this study proposes an iterative learning control (ILC) algorithm for feedforward controller of EGR and VGT systems. The feedforward controller obtains the values about EGR and VGT actuators using the previous control results in predefined transient states. The ILC algorithm consists of a PD-type learning function and a low-pass filter. The control gains of learning function are determined to guarantee the convergence of learning results. In addition, the low-pass filter is designed for robustness against plant disturbance. The proposed control algorithm was validated by engine experiment which repeated predefined transient states. The error was reduced by 15 % according to the gain. As a result, the proposed algorithm is affordable for improving the transient control performance. [ABSTRACT FROM AUTHOR]

Plug-in or add-on control is integral for high-performance control in modern precision systems. Despite the capability of greatly enhancing the steady-state performance, add-on compensation can introduce output discontinuity and significant transient response. Motivated by the vast application and the practical importance of add-on control designs, this paper identifies and investigates how general nonsmoothness in signals transmits through linear control systems. We explain the jump of system states in the presence of nonsmooth inputs in add-on servo enhancement, and derive formulas to mathematically characterize the transmission of the nonsmoothness. The results are then applied to devise fast transient responses over the traditional choice of add-on design at the input of the plant. Application examples to a manufacturing control system are conducted, with simulation and experimental results that validate the developed theoretical tools. [ABSTRACT FROM PUBLISHER]

Differential drive assistance steering (DDAS) is an emerging assisted steering mechanism in in-wheel-motor driven (IWMD) electric vehicles, yielded by the differential moment of the front tires in the steering system. DDAS can steer the front wheels when there is no steering power from the steering motor, and thus can be used as a redundant steering mechanism. To realize the yaw control when the active front steering entirely breaks down and guarantee the transient control performance therein, this paper proposes an integral sliding mode control (ISMC) approach for IWMD electric vehicles steered by DDAS. Two contributions are made in this paper: 1) An improved disturbance observer based ISMC strategy is designed to cope with the unknown mismatched disturbances, and the composite nonlinear feedback technique is employed to design the nominal part of the controller to restrain overshoots and remove steady-state errors considering the tire force saturations; 2) An adaptive super-twisting control approach is proposed to deal with the disturbances with unknown boundaries using a continuous controller while eliminating the chattering effect. The system stability and robustness are proved via Lyapunov approach. CarSim-Simulink simulation has verified the effectiveness of the proposed control approach in the case of the steering fault. [ABSTRACT FROM PUBLISHER]

The first-swing stability of synchronous generators (SGs) has a close relationship with synchronizing ability of the grid and inertia characteristic of all the generators. This paper studies inertia characteristic of doubly fed induction generator (DFIG) based wind turbine (WT) under transient control to analyze its impact on the first-swing stability of SGs. First, an analytic model of DFIG-based WT following the concept of motion equation is developed to describe and explain its inertia characteristic. The foundation is the definition of internal voltage of DFIG. Based on the model, an important conclusion is drawn that DFIG-based WT under transient control during grid fault has adjustable inertia characteristic that has a clear link with control parameters. Then, the impacts of transient control parameter of DFIG-based WT on the first-swing stability of SGs are studied through numerical simulation. Finally, the impact mechanism of transient control of DFIG-based WT on the first-swing stability of SGs is clearly explained by physical concept of inertia characteristic and synchronizing force. [ABSTRACT FROM AUTHOR]

The existing research into hybrid electric vehicle (HEV) control is mainly focussed on the optimisation of the power distribution between a conventional internal combustion engine (ICE) and an alternative power source (usually a battery pack), however, transient control, which is a key technique that affects both fuel economy and the drivability of the HEV, has not been fully addressed. Especially in dual-mode power-split HEVs, due to the different dynamic characteristics of the actuators in the transmission, and its complicated speed-torque relationship, transient control also affects the precision of power distribution and the speed of response of the electric output power. To improve the transient control performance, the design of an economic model predictive control (EMPC)-based transient controller for a dual-mode power-split HEV is developed. By incorporating an experimental identification model of a diesel ICE in a control-oriented transmission model, a better coordination among the actuators involved in HEV transmission can be achieved. Moreover, an ICE efficiency index is also added to the objective function to improve ICE fuel efficiency during this transient process. Then, a fast MPC method is applied to reduce the on-line computation effort required of the proposed control algorithm. By the flexible application of the EMPC and an innovative ICE model which is suited to the control-oriented model in EMPC, the transient control performance was improved. The effectiveness, and the real-time performance, of the control algorithm are validated by way of MATLAB™/Simulink-based simulations, as well as test-bed experiments combined with the use of the RapidECU platform. [ABSTRACT FROM AUTHOR]

Ferroresonance is phenomena, which emerged in case of different circumstances such as short circuit and breaker phase failure. In addition, plant outage is another cause of ferroresonance. Ferroresonance may cause maloperation of some protective devices such as differential protection. In this study, Manitoba hydro network is analysed in power systems computer‐aided design/electro‐magnetic transient design and control to recognise ferroresonant configurations in case of plant outage. Impact of ferroresonance on maloperation of differential protection is analysed. A static var compensator (SVC) is installed at the mid‐point of the network to mitigate ferroresonance. Operation of relay is assessed in the presence of SVC; furthermore, effect of parameters and components of SVC on operation of differential protection is investigated. Then, an adaptive algorithm is designed in differential relay to recognise ferroresonance and prevent maloperation of the relay. [ABSTRACT FROM AUTHOR]

In this paper, a variable-structure multi-resonant soft-switching DC–DC converter and its transient smooth control method are proposed. Through the introduction of auxiliary switches, the converter can flexibly adjust its structure among three operating modes. Two switching processes can be obtained. Thus, a wide voltage gain range is achieved within a narrow frequency range. Moreover, to eliminate the large voltage fluctuation during modes switching, a drive signal gradual adjustment control method is proposed. Consequently, smooth switching between different modes can be realized and the voltage fluctuation is suppressed effectively. Finally, a 200 W experimental prototype is established to verify the theoretical analyses. Soft-switching performances for power switches and diodes are both guaranteed. The highest efficiency is 98.2%. With the proposed transient control method, a basically constant 400 V output voltage is ensured within a wide input voltage range (80 V–600 V). In particular, the transient voltage fluctuations during two switching processes decrease from 38.4 V to 10.8 V and from 37.2 V to 8.4 V, respectively.

Flow separation around a lifting body was controlled using a high-speed jet generated via impulsive actuation, and important flow features associated with the transient dynamics were numerically investigated. A jet flow was impulsively applied to the VR-12 airfoil using a boundary condition modeled as a COMPACT module in the wind tunnel experiments. A delayed detached-eddy simulation based on the Spalart–Allmaras turbulence model was conducted. Computational results indicated that the aerodynamic characteristics quickly varied in the early stage after jet initiation, and that the impact of the actuation on the flow behavior was gradually reduced through a larger time scale than the freestream convection. A detailed investigation was performed to assess relevant flow features, and two distinct flow characteristics associated with the transient dynamics were identified: reattachment and recirculation. Reattachment in the early stage after actuation yielded a high suction peak near the leading edge and rapidly enhanced the lift force. Recirculation in the later stage affected gradual variations in the aerodynamic forces and moment to the baseline flow via the generation of a low-pressure region on the suction side. [ABSTRACT FROM AUTHOR]

In SOFCs, transient control of fuel utilization is achievable via input-shaping. In this paper, the approach is generalized to a feedforward control problem for second-order LTI systems with two inputs and one output. One is a measurable, time-varying, exogenous input and the other is a control input. The problem studied is exact tracking of a constant reference using the plant's DC gain vector. The problem considers plant models that can be divided into known and unknown parts, and where feedback is unavailable. Although SOFCs have nonlinear dynamics, the linear abstraction nevertheless helps predict the observed effectiveness of input-shaping. [ABSTRACT FROM AUTHOR]

In repetitive control (RC), the enhanced servo performance at the fundamental frequency and its higher order harmonics is usually followed by undesired error amplifications at other frequencies. In this paper, we discuss a new structural configuration of the internal model in RC, wherein designers have more flexibility in the repetitive loop-shaping design, and the amplification of nonrepetitive errors can be largely reduced. Compared to conventional RC, the proposed scheme is especially advantageous when the repetitive task is subject to large amounts of nonperiodic disturbances. An additional benefit is that the transient response of this plug-in RC can be easily controlled, leading to an accelerated transient with reduced overshoots. Verification of the algorithm is provided by simulation of a benchmark regulation problem in hard disk drives, and by tracking-control experiments on a laboratory testbed of an industrial wafer scanner. [ABSTRACT FROM AUTHOR]

In recent years, the main goal of the automative industry has been to reduce fuel consumption. Downsizing is a promising way to achieve this, which has shown success. Downsized, turbocharged engines suffer from slow transient torque response. This slow response is due to the slow dynamics of the turbocharger. This paper investigates the torque response of a spark ignited engine with variable geometry turbine (VGT) and variable valve timing. Optimal open-loop trajectories for the overlap and the VGT position for a fast transient response are found. This optimization is based on a 1-D simulation model. Based on this optimization, a generic feedback strategy for controlling the VGT is found. This strategy is implemented and evaluated on an engine and shows good performance. [ABSTRACT FROM AUTHOR]

The problem of controlling transient response is important in many industrial applications; for example, the speed and accuracy of motion control of robots directly relates to the productivity of the robot. The objective of transient control is to determine a feedback controller of a fixed structure that renders the closed loop response of a specified system to lie in a specified envelope. One may associate a set of errors which measures the deviation of the response from the envelope. The set of errors may be defined in such a way that all the errors are non-negative if and only if the response does not deviate from the envelope at any time. The transient problem can be thus posed as the problem of determining a stabilizing controller that renders the set of all errors to be non-negative at every time. One may associate a control parameter vector K with a controller of a specified structure. The main topic of investigation of this paper is to find a bound for the set of real control parameters, K, so that a rational, proper transfer function [ABSTRACT FROM AUTHOR]

This paper presents an alternative to the traditional dc-dc converter interfacing the battery with the inverter dc bus in plug-in hybrid electric vehicle (HEV) traction drives. The boost converter used in commercial HEVs meets with obstacles when it comes to upgrading the power rating and achieving high efficiency while downsizing the converter. A four-level flying-capacitor dc-dc converter is explored that can overcome these drawbacks by dramatically reducing the inductance requirement. A special case of the four-level converter, the 3X dc-dc converter, operates at three discrete output/input voltage ratios, thus further reducing the inductance requirement to a minimal value (almost zero). When further compared to its switched-capacitor dc-dc converter counterparts, the 3X dc-dc converter can be operated at variable output/input voltage ratios without sacrificing efficiency, and it lowers the capacitance requirement by utilizing the parasitic inductance. The operating principle, current ripple analysis, the transient control to limit the inrush current, and power loss analysis are introduced. Experimental results of a 55-kW prototype are provided to demonstrate the principle and analysis of this topology. [ABSTRACT FROM AUTHOR]

Mitigating fuel starvation and improving load-following capability of solid oxide fuel cells (SOFC) are conflicting control objectives. In this paper, we address this issue using a hybrid SOFC ultracapacitor configuration. Fuel starvation is prevented by regulating the fuel cell current using a steady-state invariant relationship involving fuel utilization, fuel flow, and current. Two comprehensive control strategies are developed. The first is a Lyapunov-based nonlinear control and the second is a standard H_\infty robust control. Both strategies additionally control the state of charge of the ultracapacitor that provides transient power compensation. A hardware-in-the-loop test stand is developed where the proposed control strategies are verified. [ABSTRACT FROM PUBLISHER]

A Raman amplifier is a type of optical amplifier that finds application in long-haul wavelength division multiplexed optical communications systems. Despite the potentially complicated nonlinear and distributed nature of the optical power dynamics that can arise in Raman amplified optical fibre links, it is shown that a number of simple modelling approaches point towards the applicability of low-order models that can satisfactorily capture the small-signal dynamics of such links in the neighbourhood of fixed set-points. Based on this observation, a simple modelling and linear control design procedure is presented with the objective of synthesising finite-dimensional feedback controllers that can achieve small-signal power transient regulation across a range of optical signal wavelengths. The application of this procedure is shown to yield satisfactory closed-loop performance and robustness in a specific simulation example. [ABSTRACT FROM AUTHOR]

Abstract: Gain transients can severely hamper the upstream network performance in wavelength division multiplexed (WDM) access networks featuring erbium doped fiber amplifiers (EDFAs) or Raman amplification. We experimentally demonstrate for the first time using 10 Gb/s fiber transmission bit error rate measurements how a near-saturated semiconductor optical amplifier (SOA) can be used to control these gain transients. An SOA is shown to reduce the penalty of transients originating in an EDFA from 2.3 dB to 0.2 dB for 10 Gb/s transmission over standard single mode fiber using a 231–1 PRBS pattern. The results suggest that a single SOA integrated within a WDM receiver at the metro node could offer a convenient all-optical solution for upstream transient control in WDM access networks. [Copyright &y& Elsevier]

• A corrective control approach actuated by multiple DERAs is proposed, which are incorporated within a reshaped transient energy function, to ensure system stability and avoid transmission over-current during severe contingencies. • A novel L1 optimization and linear matrix inequality based sparse feedback control design method to optimally select participating DERAs based on availability and capability without the linearization of the system model. • The proposed control algorithm has been tested and validated in IEEE standard 14 Bus and 118 Bus system respectively, with different fault scenario and pre-set conditions. Amongst the background of the demand of modern society for renewables and decarbonisation, the gradual penetration of distributed energy resources (DER) has been observed. While many DER studies have centered on reliability and economic issues, there is a scarcity of research on the possible grid support that aggregated DER could provide to bulk electric systems (BES). In the present paper, a novel control scheme acting with optimally selected DER aggregations (DERAs) is proposed to prevent transmission cascading from overcurrent protection in transient process. The security control scheme is obtained by reshaping a transient energy function, where the energy function not only characterises the nominal dynamic behaviour of the power system transient, but also depicts transmission tripping caused by the overcurrent. On the basis of the availability and capability thereof, the participating DERAs are selected via a sparse matrix, which is solved with linear matrix inequalities (LMIs) in the form of semi-definite programming (SDP) without the linearisation of the system model. Test examples are provided with IEEE standard 14 and 118 Bus Systems. [ABSTRACT FROM AUTHOR]

We experimentally investigate dynamic bit-error rate (BER) performance impairments induced by add-drop operations in semiconductor-optical amplifer (SOA)-based wavelength-division-multiplexing (WDM) metro-ring networks. Link control techniques in short-medium span networks provide effective performance improvement and significant BER transient reduction during add-drop operation, with respect to SOA linear operating condition (low input signal power). This behavior is confirmed by dynamic BER measurements and optical signal-to-noise penalty analysis. [ABSTRACT FROM PUBLISHER]

We propose and experimentally verify a new dynamic gain and tilt transient control technique for a multiwavelength forward-pumped Raman fiber amplifier. Using this technique, we demonstrate up to 7-dB static power excursion correction (to within 0.4 dB) and dynamic gain control with submicrosecond response. [ABSTRACT FROM PUBLISHER]

This paper proposes a fast load transient control for a bidirectional dual-active-bridge (DAB) DC/DC converter. It is capable of maintaining voltage–time balance during a step load change process so that no overshoot current and DC offset current exist. The transient control has been applied for all possible transition cases and the calculation of intermediate switching angles referring to the fixed reference points is independent from the converter parameters and the instantaneous current. The results have been validated by extended experimental tests. [ABSTRACT FROM AUTHOR]

In this paper, a variable-structure multi-resonant soft-switching DC–DC converter and its transient smooth control method are proposed. Through the introduction of auxiliary switches, the converter can flexibly adjust its structure among three operating modes. Two switching processes can be obtained. Thus, a wide voltage gain range is achieved within a narrow frequency range. Moreover, to eliminate the large voltage fluctuation during modes switching, a drive signal gradual adjustment control method is proposed. Consequently, smooth switching between different modes can be realized and the voltage fluctuation is suppressed effectively. Finally, a 200 W experimental prototype is established to verify the theoretical analyses. Soft-switching performances for power switches and diodes are both guaranteed. The highest efficiency is 98.2%. With the proposed transient control method, a basically constant 400 V output voltage is ensured within a wide input voltage range (80 V–600 V). In particular, the transient voltage fluctuations during two switching processes decrease from 38.4 V to 10.8 V and from 37.2 V to 8.4 V, respectively. [ABSTRACT FROM AUTHOR]