Influence Of Control Parameters Research Articles

The design of LLRF system for STCF storage ring

The Super Tau Charm Facility (STCF) is a new generation of high brightness electron–positron collider planned by China, designed to achieve a center of mass collision energy is 2–7[Formula: see text]GeV and a peak brightness is 0.5–[Formula: see text][Formula: see text]cm[Formula: see text]s[Formula: see text]. The digital low-level RF control system (LLRF), as the essential equipment of the storage ring RF system, is usually responsible for maintaining the stability of the cavity field. This paper presents the design scheme of LLRF for cavity in STCF storage ring, which mainly includes the hardware structure and software design of the system. We perform simulation analysis on the STCF RF system to evaluate the influence of delay and control parameters on the stability of the system and the influence of control parameters on the suppression of two kinds of noise. Desktop testing on the existing prototype demonstrates that the adopted direct-sampling architecture introduces less phase drift compared to the down-conversion architecture. Under the direct-sampling architecture, non-IQ demodulation offers better SNR and stability in both amplitude and phase. Specifically, direct-sampling in non-IQ mode achieves open-loop RMS short-term stability of 0.019% for amplitude and 0.021∘ for phase. Long-term stability in the closed-loop setting measures 0.027% for amplitude and 0.024∘ for phase.

Research on Vibration Control Regarding Mechanical Coupling for Maglev Trains with Experimental Verification

The electromagnet module, as a fundamental component providing levitation force for maglev trains, plays a crucial role in ensuring the stability of train operation. However, vibrations can easily occur due to the mechanical coupling between the two suspension points of the electromagnet module. To reveal the inherent instability of the system and the coupling relationship between the state variables, a state-space equation that considers the mechanical coupling between the two suspension points is established. Furthermore, a differential control algorithm based on geometric feature transformation is proposed to mitigate the structural coupling vibration. Simulation experiments are conducted to compare the dynamic characteristics of the system before and after implementing the improvement algorithm under complex conditions. At the same time, the influence of control parameters on electromagnetic vibration was analyzed, focusing particularly on vibrations resulting from parameter mismatch, offering crucial insights for enhancing system stability. Additionally, suspension tests are carried out on the high-speed double bogie test platform in the Key Laboratory of Hunan Province to further validate the effectiveness of the proposed algorithm. The proposed control framework is both effective and concise, making it easy to implement in engineering applications. This research holds significant practical value in improving the stability of maglev trains.

The Simulation and Parameter Optimization of the Hole-Forming Process of a Duckbilled Hole-Forming Device

This paper addresses the hole-forming process of a duckbilled hole-forming device. Based on a coupled simulation using the multi-body dynamics software RecurDyn and the discrete element software EDEM, the hole-forming mechanism of a duckbilled hole-forming device and the influence of control parameters on the hole-forming performance of the hole-forming device were studied. In this paper, we analyze the direction and speed of soil particles transported under soil disturbance by a hole-forming device through the simulation and study of the hole-forming mechanism of the hole-forming device. By controlling parameters such as the traction angle, forward speed, and mass of the hole-forming device, the influence of the control parameters on the hole-forming trajectory of the duckbilled hole-forming device was investigated. Orthogonal tests determined the optimal combination of control parameters. The results show that the hole-forming process of the hole-forming device mainly comprises squeezing and shearing the soil to form holes, and the hole-forming performance of the hole-forming device was optimal when the traction angle was 17.3°, the forward speed was 1.11 m/s, and the mass of the hole-forming device was 17.9 kg.

Nonlinear Vibration and Stiffness Characteristics Analysis of Maglev Train Based on Cubic Displacement Control

A control strategy combining cubic displacement feedback nonlinear control and proportional-differential (PD) linear control is used to control the vibration performance of the maglev system. The maglev system is divided into positive stiffness maglev system, quasi-zero stiffness maglev system and negative stiffness maglev system according to the linear stiffness value of maglev system. Firstly, an improved multi-scale method is used to analyze the vibration characteristics of suspension in the positive stiffness state of the maglev system. Secondly, the influence of control parameters on train vibration amplitude and vibration center displacement under quasi-zero stiffness is studied. Finally, the vibration characteristics of the train when the maglev system is in negative stiffness are analyzed by numerical simulation. The maglev system exhibits the worst vibration performance under negative stiffness compared with positive stiffness and quasi-zero stiffness. The suspension frame is easy to enter the chaotic motion state, and its vibration center is easy to deviate from the equilibrium position and produce large displacement when the maglev system is in the negative stiffness state. The control results show that the control strategy combining the cubic displacement feedback nonlinear control with the PD linear control can make the maglev system exhibit better vibration characteristics under positive and quasi-zero stiffness.

Modeling of virtual synchronous controlled-DFIG considering stator voltage control dynamics for transient stability analysis

Transient stability of virtual synchronous controlled (VSynC) equipment is usually analyzed without considering the dynamics of the AC voltage controller. However, neglecting the impact of stator voltage controller dynamics in doubly fed induction generator (DFIG) wind turbine can lead to inaccurate stability assessment results. In this paper, the quantitative analysis of the impact of non-forced magnetic flux and DC voltage fluctuations on transient stability is conducted. Based on these analyses, a simplified DFIG model is proposed, which is approximately equivalent to a synchronous generator with excitation regulator. Then, a discretized step-by-step calculation procedure is introduced for the proposed model. Moreover, the influence of controller parameters on transient stability is analyzed based on the calculation results. Finally, simulations and experimental validations are carried out to demonstrate the effectiveness of the proposed model.

Direct thrust control for variable cycle engine based on fractional order PID-nonlinear model predictive control under off-nominal operation conditions

With the development and complexity of aero-engines, aero-engine control has been transformed to provide proper thrust and limit protection function under the framework of multivariable control. The multi-operating modes and multi-control variables of the variable cycle engine (VCE) lead to the complex and changeable conversion between measurable variables and thrust, making the traditional indirect thrust control hard to ensure the accuracy and safety of thrust control in different operation conditions. In this paper, a direct thrust control method based on fractional order PID-nonlinear model predictive control (FOPID-NMPC) algorithm is proposed to achieve the tracking of thrust and the limitation of parameters of the VCE under nominal and off-nominal operation conditions. In view of the existing thrust estimator designs which are only suitable for nominal conditions, the individual differences and performance degradation are fully investigated. After setting the label which represents degradation mode and constructing the health index which represents degradation degree instead of estimating health parameters directly, a dual margin degradation pattern classifier is constructed based on random forest (RF), and a long short-term memory (LSTM) neural network-based thrust estimator is designed to jointly constitute the estimation module. Then, FOPID and NMPC are combined to ameliorate the control quality and ensure the accuracy and security of thrust control at different operating conditions. This method can escape from local optimum when solving multi-extremum optimization problems. The comparative simulation of the proposed FOPID-NMPC with PID-NMPC and NMPC is performed and the influence of controller parameters on thrust response is explored. Simulations show that the designed controller has better dynamic performance, and also has good steady-state performance and safety.

Influence of control parameters on accuracy and reliability of the jet-dispensing process

Influence of control parameters on accuracy and reliability of the jet-dispensing process

Tracking-Differentiator-Based Position and Acceleration Feedback Control in Active Vibration Isolation with Electromagnetic Actuator

In order to improve the performance of the active vibration isolation system (AVIS) with electromagnetic actuator, several problems of vibration control are studied. Position control is a critical component in suspension systems, and the position sensor noise can extremely affect the stability of the system, so a tracking differentiator (TD) is proposed to obtain effective differential signal from relative position sensor. In vibration control, the feedback of acceleration combined with PD position feedback is presented to suppress transmission of periodic vibrations. Then, taking the acceleration transmission as the evaluation index, the acceleration transmission under the presented control method is derived, and the influence of control parameters on vibration isolation performance is discussed in detail. The vibration isolation performance is improved from 24.47 dB to 2.4 dB at resonance frequency, and −34 dB attenuation is achieved at 100 Hz with respect to vibration isolation mount system tested on the ground. The experimental results demonstrate that the performance of active vibration isolation system are improved by the proposed acceleration feedback control.

Detailed Wideband Impedance Modeling and Resonance Analysis of Grid-Connected Modular Multilevel Converter

Modular multilevel converter (MMC) tends to cause resonance instability in interconnected systems. Current studies on the stability of MMC mainly focus on high-voltage and large-capacity power systems, while the impedance modeling process of MMC ignores the harmonics of the submodule (SM) capacitor voltages and the influence of voltage feedforward control. The applicability of the MMC impedance model with fewer submodules is doubtful. According to the circuit structure and control mode, the AC-side sequence impedance model of the MMC is established, which takes into account the capacitor voltage balance control of submodules and voltage feedforward control. Based on the RT-Lab control hardware-in-loop (CHIL) test platform, the MMC impedance frequency scanning was carried out to verify the accuracy of the impedance modeling method. The influence of control parameters in different frequency bands on the impedance characteristics of MMC was studied. The AC terminal voltage feedforward causes phase lag in the mid-/high-frequency range and increases the risk of resonance. In the low-frequency range, the dynamics and control of capacitor voltages reduce the impedance magnitude of MMC. Using the resonance phenomenon of an MMC connected to a weak grid as an example, the high-frequency resonance mechanism caused by control parameters is analyzed from the perspective of the negative damping effect. The simulation results show that the detailed wideband impedance model can improve the accuracy of the stability analysis results.

Power Feasible Region Ensuring Transient Stability of Droop-Based Multiconverters DC System

This article systematically focuses on the transient stability problem of droop-based multiconverters dc (MCdc) system caused by large power disturbances. Therefore, a new and effective transient stability analysis method is proposed. In the present method, it starts with reduced-order nonlinear mathematical modeling, followed by Lyapunov energy function building, and then the inscription of the largest estimated domain of attraction (LEDA) and the power feasible region (PFR). First, a state-variable equivalent transformation method is proposed. With this method, the droop-based MCdc system can be modeled as an equivalent single-converter (ESC) model without ignoring any coupling effects between the control state-variables. Second, a Takagi–Sugeno fuzzy model of the ESC is developed, which is able to construct the LEDA. Third, to ensure the transient stability of the MCdc system under large power disturbance, the concept of PFR is proposed. Furthermore, a PFR inscription algorithm is given based on the LEDA. In addition, the influence of control parameters on the PFR is analyzed, which will provide guidelines for the optimization of the PFR. Finally, the time domain experiments are carried out on the RT-BOX hardware-in-the-loop experimental platform to verify the effectiveness of the above theoretical analysis.

Influence of Control Parameters during Drilling of Aluminum Reinforced with HNT Hybrid Matrix Composites

The current paper aims to find the optimum control parameters such as weight percentage of HNT, weight percentage of boron nitride, drilling speed, and feed rate in drilling of aluminum hybrid metal matrix composites. The aluminum matrix material are reinforced with different weight percentage of HNT (3%, 5%, and 7%) and BN (2%, 3%, and 4%). The hybrid matrix are fabricated through the sir casting technique. The prediction of process parameter are optimized using Taguchi assisted grey relation analysis. Also the ANN model is developed to predict the output parameter. Through Taguchi S/N ratio method the effect of each control parameters are optimized. The results show that the weight percentage of HNT and feed rate are the most influencing parameters which affect the drilling of developed aluminum composites. The GRA results show that the optimum parameters are 3% of HNT, 4% of BN, 500 rpm drilling speed, and 20 mm/min in combination, which has minimum surface roughness, lower temperature, highest cutting force, and highest material removal rate.

Optimization Process of Potassium Carbonate Activated Carbon through Jute-Based Core Materials by Using Artificial Neural Network with Response Surface Methodology

Potassium carbonate was tested as novel information for producing carbonaceous materials from jute cores. Two quadratic models have been developed for both answers to link the preparatory parameters: activating temperatures, molar ratio, and incubation time. The RSM and ANN models were used to improve the processing conditions to maximise the quantities of iodine and methylene blue penetration. The best charcoal was obtained using 900°C activating temperatures, a 1.5 molar ratio, and a 4-hour activating time. This resulted in iodine and methylene blue absorption of 1260.07 mg/g and 369.21 mg/g, respectively. It was discovered that the K2CO3-based pyrolysis process might be anticipated to become a safe yet incredibly efficient process of making activated carbons with a very well-defined and monocultural porous structure. Even though the precise emphasis given to K2CO3 is unknown at the moment, given the creation of K2C3O4 just after evolvement with one additional molarity of CO at approximately 870°C, these same porous and papule responses begun by K2CO3 stimulation might be temporarily posited to be quite comparable to an initiation action needed to make progress by K2C3O4. The influence of control parameters was examined in this study using variance analysis like the ANOVA test. Furthermore, the response surface (RSM) and artificial neural networks (ANN) are employed to improve the output results while optimising the methylene blue and iodine qualities. Consequently, the experimental findings correlate well with the statistics.

An improved robust model predictive and repetitive combined control for three-phase four-leg active power filters with fixed switching frequency

An improved robust model predictive control (MPC) method for a three-phase four-leg active power filter (APF) is proposed in this paper. First, the decoupling model in abc coordinates of the four-leg APF is derived, and then an optimal control law is also deduced based on the calculation of the partial derivation of the cost function, which is composed of the current tracking error and control quantity with a weighted coefficient. In addition, repetitive control (RC) is introduced to eliminate the prediction error inherent in the model. Finally, the influence of control parameters on the stability of the system is analyzed by the Jury stability criterion, the performance of the proposed method has also been investigated with the perturbations of the filter inductor parameters, and strong robustness, fixed switching frequency and rapid dynamic response of the whole system can be obtained. Simulation and experimental results show the effectiveness and feasibility of the proposed method.

An inertia‐emulation‐based cooperative control strategy and parameters design for multi‐parallel energy storage system in islanded DC microgrids

This paper proposes an inertia-emulation-based cooperative control strategy for the multi-parallel energy storage system (ESS) to meet the requirements of state-of-charge (SoC) balance, inertia enhancement and zero-steady-state voltage deviation. The inertia emulation loop (IEL) is constructed by analogy with DC motors to dampen voltage oscillation, while the secondary voltage recovery loop is derived from the circuit equivalence of an inductor to indicate the system stiffness. Moreover, to equalize SoCs of energy storage units (ESUs) dynamically, a SoC self-balance algorithm is developed. The redefined SoC mismatch degree and balance speed adjustment factor k are introduced into the droop resistance, adjusting the SoC self-balance rate and eliminating the SoC deviation among ESUs. The dynamic performance of the SoC self-balance algorithm is analyzed and the small signal model of the DC microgrid (DC-MG) with proposed strategy is established. Based on eigenvalue analysis and step response, the system stability is assessed, and the influence of control parameters on transient characteristics and stability margin is investigated. Considering power constraint, voltage deviation constraint and dynamic stability constraint, the optimal design method of k is given. Finally, simulation and experiment verify that the proposed control, without modifying hardware, performs better dynamic and static characteristics and can equalize SoC among ESUs in charge and discharge mode.

Describing Function Analysis of Sustained Oscillations in Grid-Tied Voltage-Source Converter With Double Saturation Limiters

Recently, with the fast development of renewable energy, various power-electronic-based devices have been widely incorporated in power systems, and controller saturation limiters have been broadly utilized, such as in voltage-source converter. It has been well recognized that these saturation limiters make sustained oscillations possible. To study the impact of saturation limiters, by considering the dynamical response of double saturation limiters in both the d-axis and q-axis of the alternating current control, this paper establishes single-input-single-output models for two novel phenomena including the double-clipped oscillation and single-clipped oscillation, based on the describing function. Then the describing-function-based Nyquist criterion is used to obtain the amplitude and frequency of the sustained oscillations. The model accuracy is verified by the electromagnetic transient simulation, and the influences of control parameters are extensively studied. All these findings clearly demonstrate that the saturation limiters play an active role in sustained oscillations in power-electronic-based power systems.

Quantifying chaotic dynamics of nanobeams with clearance

We investigate chaotic dynamics and contact interaction of geometrically nonlinear (according to the Kármán model) beam nanostructures with a small clearance. Contact interaction is described by the Kantor’s model. The constructed mathematical models are based on the first-order (Euler–Bernoulli) and the second-order (Timoshenko) kinematic approximations with the help of the modified couple stress theory. The fundamental governing dynamical equations of two-layer beam nanostructures are yielded by Hamilton’s principle.The paper substantiates the validity of the obtained solutions for the problem of contact interaction of two nanobeams, subject to different kinematic hypotheses. When solving problems by numerical methods, errors accumulate, which are very often mistaken for chaotic oscillations. In this paper, we propose a methodology for identifying “true” chaos for mechanical beam size-dependent structures and obtaining reliable results.The governing PDEs are reduced to ODEs by finite difference method (FDM) of the second-order and the Bubnov–Galerkin method in higher approximations. The obtained ODEs are solved by the Runge–Kutta and Newmark methods. Results of convergence versus the number of partition points along the spatial coordinate in the finite difference method, the number of series members in the Bubnov–Galerkin​ method and time steps are investigated. The revealed chaotic/hyper-chaotic vibrations are studied by nonlinear dynamics methods, wavelet analysis, and the spectrum analysis of the Lyapunov exponents. The numerical methods are validated by estimating the temporal and spatial convergence, while the reliability of the obtained solution is validated by the Lyapunov exponents obtained through the analysis of the results from four different qualitative methods. The numerical solution is obtained by several methods at each simulation step. The influence of control parameters (the transverse harmonic load and the size-dependent parameter) on the two-layer beam vibrations is reported.

Malicious software spread modeling and control in cyber–physical systems

Cyber–physical systems are interactive intelligent systems integrating computing units and physical objects through information networks. They have been widely used in critical infrastructures, and are increasingly vulnerable to malicious software attacks. To explore the spread mechanism of malicious software in cyber–physical systems from a macroscopic perspective, this work proposes a new malicious software spread model with time delay, and analyzes its complex dynamic behavior by using the stability theory and bifurcation theorem. A hybrid bifurcation control method is presented to control adverse bifurcations that cause harmful behavior of cyber–physical systems, and the influence of control parameters on the Hopf bifurcation threshold is revealed. Cyber–physical systems with the proposed method can be stabilized, which behave as expected during malicious software spread. The simulations show that the proposed control method can advance or postpone the threshold of Hopf bifurcation, thus making cyber–physical systems achieve a stable state. Consequently, damage and disruption to cyber–physical systems caused by malicious software are effectively reduced.

The Influence of Control Parameters on Precision of Welding Seam Tracking in Manually Control Master-slave Robot Remote Welding System

The welding seam tracking precision is one of the key factors to ensure welding qua ntity. However, when the operator manually manipulate the master robot to control the slave ro bot tracking welding seam used the master- slave robot remote welding system, seam tracking precision does not meet the requirement of the welding quantity, the influence of control param eters on precision of welding seam tracking is unkown. In this article, a master-slave robot rem ote welding system is set up which includes a master robot with 6 degrees of freedom, a compu ter control system, and robot HP3J carrying a welding torch and laser sensor system. The slave robot tracking welding seam was controlled by computer control system and the human operat or via master manipulator. The influence of control parameters (cross deviation, arc length and welding speed) on precision of welding seam tracking was analysed. The experiment results de monstrate the more control parameters of operator, the lower tracking precision, so in order to guarantee a good welding seam tracking effect, the operator should control less parameters.

Quantification and evaluation of ion transmission efficiency in two-stage vacuum chamber miniature mass spectrometer.

Miniature mass spectrometer is more compact and portable than traditional commercial mass spectrometry, with more potential for application outside the laboratory. However, a miniature mass spectrometer is less sensitive than a commercial instrument, limiting its application scenarios. The ion transmission efficiency of the instrument is an essential factor affecting the sensitivity. Still, there are few works of literature on the quantitative study of the ion transmission efficiency of each component from a systematic perspective. In this paper, the Faraday cup coupled with a microcurrent signal testing instrument was used to measure the ions generated by nanoelectrospray ionization (nano-ESI), which have successfully gone through several components. Then the ion transmission efficiency of each component was quantified. Results showed that the front lens had the highest ion transmission efficiency of 39.7%, whereas the inlet and skimmer had the lowest ion transfer efficiency of 0.8% and 17.1%. Next, the influence of control parameters on ion transmission efficiency of critical components was investigated. If optimized, the ion funnel and the skimmer had the potential to improve their transmission efficiency by 120% and 79%, respectively. This paper shows the decreasing intensity distribution of ions in the whole transmission process and the transmission efficiency of each component, which can guide for improving the sensitivity of the miniature mass spectrometer.

Research on transient stability control method for LCC‐HVDC receiving‐end system based on the gradient of dynamic energy

A new transient stability control strategy for the Line-Commutated-Converter based High-Voltage-Direct-Current (LCC-HVDC) receiving-end system based on the gradient of dynamic energy is proposed to deal with this problem. Firstly, in the whole process from fault occurrence to fault removal, a dynamic energy function representing the stability of the system is constructed. On this basis, considering the influence of Direct Current (DC) inverter side controller, the dynamic energy gradient expression under three-phase and single-phase short-circuit fault scenarios is deduced in detail. The influence of control parameters on dynamic energy accumulation or consumption is analytically described. Then, the function term related to the inverter side controller is extracted from the dynamic energy gradient expression, the trigger pulse on the inverter side is controlled to keep the dynamic energy gradient of the DC port at the minimum. Finally, the hardware in the loop test is carried out on RT-LAB. The test results show that in the process of receiving end fault, the DC port will inject dynamic energy to the receiving end system, making the system tend to be unstable. This method is able to reduce the dynamic energy accumulation rate of system and increase the critical clearing time of system.