Versatile Control Strategy Research Articles

Transport control of a swivel crane based on a vibration-less trajectory (A versatile control strategy)

Transport control of a swivel crane based on a vibration-less trajectory (A versatile control strategy)

Concept for a multi-purpose EU-DEMO pellet launching system

Pellets - mm-size solid bodies produced from frozen fuel – are mainly destined for fuelling purposes in the fusion reactor EU-DEMO. However, pellets have been proven capable tools for further tasks too, e.g. ELM frequency control and the efficient delivery of seeding gases have been already demonstrated. Here, a concept is presented for a single pellet launcher based on a stop-cylinder centrifuge accelerator equipped with multiple pellet sources. The sources can deliver pellets with different sizes and composition, finally combined into one single compound pellet train. Thus, the pellet launching system (PLS) is capable to control simultaneously different plasma parameters with a minimized cross talk between these different actuations. Currently, a new PLS is under development for the new large superconducting tokamak device JT-60SA which can be potentially regarded as a prototype for the envisaged EU-DEMO system. Its initial configuration will be capable to control plasma density and ELM pacing simultaneously; optionally a source for doped pellets can be added. Status and recent achievements of this systems are reported. At the full metal wall mid-size tokamak ASDEX Upgrade (AUG), work is ongoing developing a versatile control strategy and corresponding tools. Capable to inject pellets with high speed through a guiding tube from the torus inboard side, AUG represents a fully reactor relevant configuration. While all demonstrations have been performed with a single pellet source hence bound to actuation prioritizing one actuation parameter, all tools developed can be expanded straightforwardly to multi-purpose control. For example, one novel tool optimizes real-time feedback pellet flux control taking into account the discrete nature of the pellets. As well, a solution is worked to handle the issue of missed-out pellets. Such failed pellets are considered unavoidable due to the fragile nature of the solid fuel but identified as significant hazard for reactor burn control.

A versatile control strategy based on organic carbon flow analysis for effective treatment of incineration leachate using an anammox-based process

Anammox-based process provides an alternative for the sustainable treatment of incineration leachate that has high-load ammonium and high residual heat, but the high concentrations of organics in such leachates brought challenges for the process control. For the first time, a two-stage partial nitrification (PN)-anammox process coupled with a pre-enhanced anaerobic digestion (AD) was established to achieve efficient nitrogen removal from incineration leachate. Satisfactory nitrogen and chemical oxygen demand (COD) removal efficiencies were achieved—with the average values of 90% and 78%, respectively—despite fluctuating influent properties [1100–2000 mg-total nitrogen (TN)/L and 3800–15800 mg-COD/L]. A versatile control strategy was developed to create an optimum autotrophic environment for nitrifier and anammox bacteria: i) enhanced AD set before the PN-anammox process captured nearly 50% of the influent COD; ii) in the PN unit, ammonia-oxidizing bacteria were well adapted to COD concentrations of 1420–2400 mg/L, and dissolved oxygen (0.2–0.4 mg/L) controlling combined with a high free nitrous acid concentration (>0.08 mg/L) ensured a nitrite accumulation rate of >95%; and iii) in the anammox unit, a suitable influent NO2−-N/NH4+-N ratio (the average value of 1.27) was achieved by mixing AD effluent with PN effluent (1:1.78, v/v), contributing to a high TN removal of 78 ± 2.4%. Nevertheless, 980–1560 mg/L of COD remained in the influent of the anammox unit; biorefractory humic acids in this (245.6 ± 3 mg/L) might be the main component that caused the observed 66 ± 2% decrease in anammox activity. The proliferation of denitrifying bacteria and sulfate-reducing bacteria induced by the organic compounds may have led to the observed decline in the abundance of the anammox bacterium Candidatus Kuenenia. The proposed strategy guaranteed the robust operation of the PN-anammox process and provides a promising approach for the sustainable treatment of incineration leachate.

Thermal control of laser powder bed fusion using deep reinforcement learning

Powder-based additive manufacturing techniques provide tools to construct intricate structures that are difficult to manufacture using conventional methods. In Laser Powder Bed Fusion, components are iteratively built by selectively melting specific areas of the powder bed to form the two-dimensional cross section of the specific part. However, the high occurrence of defects impact the adoption of this method for precision applications. Therefore, a control policy for dynamically altering process parameters to avoid phenomena that lead to defect occurrences is necessary. A Deep Reinforcement Learning (DRL) framework that derives a versatile control strategy for minimizing the likelihood of these defects is presented. The generated control policy alters either the velocity or power of the laser during the melting process to ensure the consistency of the melt pool and reduce overheating in the generated product. The control policy is trained and validated on efficient simulations of the continuum temperature distribution of the powder bed layer under various laser trajectories.

Control strategies for power quality enrichment in Distribution network using UPQC

Unified Power Quality Conditioner (UPQC) is a cutting-edge Custom Power Device (CPD) that is being used to improve power quality in the distribution network. UPQC contributes to the distribution network by compensating for both voltage and current-related power quality disturbances. Its control strategy in unbalanced and distorted weak grid conditions is of particular interest for research. In addition, the performance of UPQC in the presence of unbalanced and non-linear harmonic loads is critical for maintaining desirable power quality. This paper investigates the implementation of UPQC control strategies and algorithms for improving power quality (PQ) and proposes a versatile control strategy to improve UPQC performance. When tested on a critical distribution network, the proposed dynamic control strategy provides better steady-state and dynamic response. Models developed in MATLAB/SIMULINK are used to validate the proposed control scheme.

Power factor adjustment and input current distortion mitigation for three‐phase unidirectional rectifier

In order to improve the power quality, many researchers in the worldwide are committed to investigating the feasibility of integrating reactive power compensation (RPC) and harmonic current compensation (HCC) functionalities for unidirectional rectifier, while the capability of RPC for unidirectional rectifier is very limited. Hence, with the aim of enlarging the capability of RPC for unidirectional rectifier, this article introduces a versatile control strategy for three-phase star-connected unidirectional rectifier. The operating principle and the reasons that limit the capability of RPC for unidirectional rectifier are analysed in detail. On this basis, a novel criterion for judging input current distortion zone is proposed. Furthermore, the additional focus of this article is to quantify the constraint relationship between the degree of input current distortion compensation and input power factor regulating range. Simulations and experimental results are conducted to verify the feasibility and effectiveness of the proposed control strategy, as well as the correctness of the theoretical analysis on the proposed constraints of the input power factor regulation.

An unusual kind of complex synchronizations and its applications in secure communications

In this paper, we talk about the meaning of complex anti-syncrhonization (CAS) of hyperchaotic nonlinear frameworks comprehensive complex variables and indeterminate parameters. This sort of synchronization can break down just for complex nonlinear frameworks. The CAS contains or fuses two sorts of synchronizations (complete synchronization and anti-synchronization). In the CAS the attractors of the master and slave frameworks are moving opposite or orthogonal to each other with a similar form; this phenomenon does not exist in the literature. Upon confirmation of the Lyapunov function and a versatile control strategy, a plan is made to play out the CAS of two indistinguishable hyperchaotic attractors of these frameworks. The adequacy of the obtained results is shown by a simulation case. Numerical issues are plotted to decide state variables, synchronization errors, modules errors, and phases errors of those hyperchaotic attractors after synchronization to determine that the CAS is accomplished. The above outcomes will present the possible establishment to the secure communication applications. The CAS of hyperchaotic complex frameworks in which a state variable of the master framework synchronizes with an alternate state variable of the slave framework is an encouraging kind of synchronization as it contributes fantastic security in secure communications. Amid this secure communications, the synchronization between transmitter and collector is shut and message signs are recouped. The encryption and reclamation of the signs are reproduced numerically.

A Control Strategy for Reliable Power Output From a Stand-alone WRIG With Battery-Supported DC Link

This paper proposes a versatile control strategy for a standalone wound rotor induction generator (WRIG) with back-to-back converters supported by a battery at dc-link. The principal feature of the study is the operation of the generator as a commanded current source, to supply only sinusoidal current as desired, and the operation of battery fed Front End Converter (FEC) as a constant voltage source, which adapts to varying load conditions. Further, in implementing this feature, in a significant deviation from conventional approaches, to Rotor Side Converter (RSC) and FEC are redefined with a view to achieve versatility and reliability in stand-alone operation. In particular, the RSC is employed to track the maximum power (instead of load voltage and frequency control), whereas the FEC maintains a constant load voltage and frequency. It is revealed that there are multiple benefits of the proposed strategy such as inherent load balancing; capability to support critical loads solely by battery through the FEC as in an uninterruptible power supply (UPS), especially at low wind speeds; compensating unbalanced or harmonic load currents via FEC (as in an active power filter); and smooth transition between the MPPT mode and the UPS mode by synchronization. Simulation results of a 2-MW wind turbine, along with test results of a 2.3-kW laboratory setup, validate the proposed strategy.

Integration of solar photovoltaic with battery to single‐phase grid

This work deals with the control of a solar photovoltaic array and a battery storage integrated into a grid. It has versatile control strategy as it provides with maximum power point tracking, battery charging/discharging and a grid current at unity power factor. This configuration along with its control helps in feeding a constant power to the grid and maintains the controlled power dynamics in the system. The control performs a voltage control of the boost converter, current control of grid and DC-link voltage control along with current control of the battery and adapts itself according to the environmental conditions such as no/low solar insolation and absence of battery storage. The proposed system is designed for a maximum power of 5 kW and simulated in MATLAB-based environment. Test results on a prototype developed in the laboratory verify the simulated results. Under steady-state condition, the total harmonic distortions of grid voltage and current are within the range of an IEEE 519 standard. Simulations and experimental results of the proposed system are demonstrated for various dynamic changes.

Knowledge base generation and its implementation for control of above knee prosthetic device based on SEMG and knee flexion angle

Advanced intelligent knee prosthesis for trans-femoral amputees requires a versatile control strategy and associated control algorithm. Control strategy was evolved by mapping surface EMG (SEMG) from four muscles of healthy lower limb of a unilateral trans-femoral amputee and knee flexion angles (KFA) during various phases of a gait cycle. The SEMG and KFA are calibrated to three walking speeds modes i.e., slow, normal and fast. Sensor mechanisms feeds real-time data to controller to generate an appropriate control output signal based on available knowledgebase which calculates the patient's gait parameters i.e., KFA and SEMG from associated muscles during the corresponding phase of walk. Important aspect of control strategy is the development of knowledgebase proves that the SEMG signal generates recognisable pattern for change in walking speed when signals were analysed in time and frequency domain. These patterns were quantified and utilised for controlling electro-pneumatic knee joint.

Active Vibration Control by Maximum Power Absorption.

The purpose of this paper is to propose a novel active control strategy to reduce noise and vibration. Much work has been done on the active control of noise and vibration. However, one of the limitations of the technique is that controllers tend to be application-specific. Careful identification of the system to be controlled and reference signals are essential and that often proves difficult to arrange. Hence a versatile control strategy, which is non-application-specific, has been sought in this research. The power absorbed by an active vibration controller was taken as a cost function to be maximised. Theoretical investigations into simple string models have been conducted with this idea, suggesting that power absorption maximisation within the time taken for a wave emitted by the controller to come back to the control point, i.e. within a sing around time, is promising. A maximum power absorber based on this strategy was developed for experimental purposes, and applied to string and plate models for its validation study. These experiments confirmed that the absorber attenuates vibration effectively, supporting the good prospect of this control strategy.

A Programmable Electromagnetic Bearing for Vibration Control of a Flexible Shaft

The transverse vibrations of flexible rotors can be reduced to safe levels by radial control forces at an intermediate span position, applied by a suitable actuator. One versatile control strategy applies forces proportional to displacement and velocity, with coefficients dependent on the rotational speed. This control can be realized with an electromagnetic bearing under microprocessor control. Suitable microprocessor software is described, to implement the required real-time computation of the control forces. Experimental results obtained from a test rig are compared with theoretical predictions. There are advantages in allowing the stiffness coefficient to become negative, provided that positive damping is simultaneously applied.