Parameter Optimization Design Method Research Articles

Optimization and evaluation of tuned inerter-based dampers for mitigating coupled responses of offshore wind turbines

To achieve lightweight vibration control in offshore wind turbines (OWTs), this study proposes the utilization of two types of tuned inerter-based dampers (TIBDs), namely, the tuned viscous mass damper (TVMD) and tuned inerter damper (TID), to mitigate the coupled responses of an OWT induced by wind and wave loads. First, a multi-degree-of-freedom (MDOF) lumped mass model is established to represent an OWT equipped with a TIBD. Then, a novel structural control module for TIBDs is developed and seamlessly integrated into the modular numerical analysis code OpenFAST. This enables fully coupled aero-hydro-servo-elastic simulations of the OWT-TIBD system. Using the established MDOF model, a TIBD parameter optimization design method is proposed to minimize the peak of the non-dimensional displacement frequency response function. Additionally, a parametric study is performed to investigate the effect of inertance and span height on the control performance. Finally, the performance of the TIBD in attenuating both fatigue and extreme loads is evaluated through nonlinear fully coupled time-domain simulations using OpenFAST and compared to traditional tuned mass dampers (TMDs). The results showed that a lightweight and small damper displacement TIBD is capable of effectively dampening OWT vibrations, yielding a better mitigation effect than that provided by a bulky TMD. Overall, the reduced installation requirements and the commendable control efficiency of a TIBD highlight its potential as a promising candidate for passive control devices in OWT applications.

Design, analysis, and optimization of PMSM for ultra-deep water pile hammer application

With the development of global deepwater oil and gas and offshore wind power resources, there is an increasing demand for ultra-deep water pile hammers (UDPH). In this paper, a permanent magnet synchronous motor (PMSM) with oil fill is proposed for UDPH on the basis of underwater 2500 m depth and 450 kJ impact energy requirements. First, the rated parameters of the PMSM are calculated based on the power required by hydraulic pumps, and then, the method of combining empirical formulas and path algorithms is used to complete the electromagnetic scheme design. Second, finite element analysis of the electromagnetic field is carried out by Maxwell under both no-load and load conditions to verify the rationality of the PMSM. Furthermore, aiming at improving efficiency and reducing cogging, parameter optimization is carried out by a robust parameter optimization design method, and the optimal parameter scheme of the PMSM is obtained. In addition, loss analysis and temperature field coupling calculations of the optimized PMSM are conducted to verify that the temperature of this motor can meet the requirements under different working conditions. Finally, a comparative analysis is conducted between the proposed PMSM and the three-phase asynchronous motor used in the underwater 2,500 m-450 kJ UDPH. The results indicate that the new PMSM introduced in this paper demonstrates significant advantages in terms of weight, volume, and efficiency; moreover, the new PMSM is reasonable and more suitable for UDPH. Therefore, the PMSM proposed in this paper is reasonable and can provide a theoretical basis for improving the traditional UDPH.

A D-T Hybrid DC FCL and Its Parameter Optimization Design Method for Application in Multiterminal VSC-HVDC Grids

A D-T Hybrid DC FCL and Its Parameter Optimization Design Method for Application in Multiterminal VSC-HVDC Grids

An optimizated additional damping control for suppressing ultra‐low frequency oscillation suppression based on SVC

AbstractThe ultra‐low frequency oscillation (ULFO) imposes an emerging stability challenge to the high proportion of hydropower grids. To suppress ULFO without reducing the primary frequency regulation of the hydro governor, a novel idea to exploit the voltage regulation effect of load is implemented. First, the additional damping controller is designed and configured in static var compensator (SVC), and the frequency analysis model considering the configuration of SVC as well as damping controller is established. Based on the model, the specific influence of SVC and controller on ULFO is analysed through eigenvalue calculation. In addition, the influence of various load models and SVC location on the damping level are further studied. Consequently, a parameter optimization design method for SVC additional damping control is proposed, it is modelled as the optimization problem of damping ratio in ULFO mode under multi‐operation conditions, which is solved by a particle swarm optimization algorithm. Finally, the effectiveness of the designed SVC additional damping controller is verified in the improved four‐machine two‐area power system and the actual power grid in China.

A Parameter Optimization Design Method for Single-Phase Dual Active Bridge AC-DC Converter

The single-stage dual active bridge (DAB) AC-DC converter has the advantages of high power density, low cost, and simple control; it has a broad potential for application in the field of onboard chargers (OBC). However, the lack of fast and accurate quantitative parameter optimization design methods in single-stage DAB AC-DC converters limits the overall efficiency of the converter. Based on the above problem, in order to improve the overall operating efficiency of the converter by optimizing the parameter transformer ratio and power inductance, this paper proposes a parameter design method considering a multi-timescale strategy by combining the steady-state analysis model of the converter in the line cycle and switching cycle and step-by-step reducing its design space through the constraints on the parameters. The first step is to obtain a safe design space for the parameters under the converter’s transmitted power and current stress constraints. The second step obtains the optimization design space of the parameters under the optimization of conduction loss and switching loss of the converter. Finally, the optimal parameters are determined by the loss analysis model. The proposed parameter optimization method entirely takes into account the steady-state characteristics of the DAB AC-DC converter during the line cycle, and the step-by-step constraints greatly accelerate the parameter design process. In addition, the proposed parameter optimization design method applies to all types of single-stage DAB AC-DC converters, which can be well applied to engineering practice.

Analysis of Grid-Connected Stability of VSG-Controlled PV Plant Integrated with Energy Storage System and Optimization of Control Parameters

In the static stability analysis of the grid-connected photovoltaic (PV) generation and energy storage (ES) system, the grid-side is often simplified using an infinite busbar equivalent, which streamlines the analysis but neglects the dynamic characteristics of the grid, leading to certain inaccuracies in the results. Furthermore, the control parameter design does not consider the coupling relationships among parameters, resulting in arbitrary values and the inability to achieve overall optimality. To address these issues, this paper presents a comprehensive parameter optimization method for the oscillation characteristics of grid-connected PV generation and ES systems in various frequency ranges. Firstly, a detailed modeling of the grid-connected PV generation and ES system is conducted, resulting in the derivation of the system’s small-signal model. This study investigates the impact of parameters related to PV arrays, ES units, and the virtual synchronous generator (VSG) on the system’s characteristic roots using participation factors, sensitivity analysis, and eigenvalue root trajectories. Subsequently, based on the analysis of system root trajectories and the Particle Swarm Optimization (PSO) algorithm, a holistic parameter optimization design method for the system’s oscillation modes is proposed, and the parameter optimization results are obtained. Finally, the accuracy of the theoretical analysis is validated through perturbation testing using both Matlab/Simulink models and the small-signal model.

Dead-time compensation and single-loop control strategy for ground power unit

Instead of the auxiliary power system, the ground power unit supplies to airplanes during stopovers in airports, which is an important means of reducing carbon emissions of airport. However, under the restraint of switching frequency and high dynamic response speed, a single control loop is usually implemented in 400 Hz voltage-source inverter, the sampling and control of the inductor current in the LC filter are avoided, result in the design of the control system being more difficult, and the direction of the dead-time compensation can not be obtained due to the lack of the current polarity. In view of the above problem, this paper firstly analyzes the influence on the output voltage of inverter due to the dead-time, including the errors of fundamental amplitude and phase, and the low-order harmonic distortion. Then, according to the state equation of the inductor current, a current observation model without zero drift is proposed to obtain the polarity of the inductor current. On this basis, feedforward compensation is carried out for the voltage error generated by the dead-time. Combined with the amplitude-frequency characteristic curve, the parameter optimization design method of the single closed-loop proportional-resonant controller is presented. Finally, a simulation model and an experimental platform are established to verify the feasibility and effectiveness of the current observation model, dead-time compensation method and controller parameter optimization design method proposed in this paper.

Optimization Mechanism of Nozzle Parameters and Characterization of Nanofibers in Centrifugal Spinning

Nanofibers are an emerging kind of nano-material, widely used in several application domains such as biomedicine, high-efficiency filtration media, precision electronics, and optical devices. Centrifugal spinning, which is a novel nanofiber production technology, has been widely studied. This paper proposes a structural parameter optimization design method of a bent-tube nozzle. The mathematical model of the spinning solution motion in the nozzle is first developed. The optimization function of the structure parameters of the bent-tube nozzle is then obtained by calculation. Afterwards, these parameters are optimized using a neural network algorithm. The obtained results show that, when the bending angle is 15°, the curvature radius is 10 mm, the outlet radius is 0.205 mm, and the head loss of the solution can be minimized. Finally, centrifugal spinning experiments are conducted and the influence of the centrifugal spinning parameters on the nanofibers is analyzed. In addition, the optimized bent-tube nozzle improves the surface morphology of the nanofibers as their diameter distribution becomes more uniform.

A parameter optimization method of multi-layer nested slit resonator for the converter transformer noise in high voltage direct current converter station

We propose a parameter optimization method of multi-layer nested slit resonator (MNSR) for the converter transformer noise in a high voltage direct current (HVDC) converter station. With the optimization objective of achieving quasi-perfect sound absorption at the target frequencies and the structural parameters of MNSR as the optimization variables, the optimization model of the structural parameters of MNSR is established and then solved by the sequential quadratic programming algorithm (SQP). The theoretical and simulation results of the four validation cases show that the optimized MNSR can achieve quasi-perfect sound absorption at all target frequencies, which is consistent with the optimization objective. The parameter optimization design method provides an efficient method to design a dual-frequency quasi-perfect sound absorber for the converter transformer noise.

High nonlinearity of BEV's stepped automatic transmission design objectives and its optimal solution by a novel ISA-RSA

The battery electric vehicle's (BEV's) stepped automatic transmission (SAT) has a significant influence on the power and economic performance of the new-energy vehicle system dynamics. The SAT entails a complex design process, where the transmission ratio parameter and the control strategy are interactively coupled, causing a difficulty in achieving a globally optimal solution. The actual design process involves multiple design objectives and incurs high design costs. The purpose of this study is to explore the variation characteristics of the design objectives of BEV's SAT and propose a transmission parameter optimization design method with reduced design costs. The paper investigates the interactive coupling property of the transmission ratio parameter and the control strategy, analyzing the high nonlinearity of SAT design objectives using the example of two-gear transmission. It proposes a design method that combines a heuristic optimization algorithm and an estimation model (Method Ⅲ), and a design method that utilizes an improved simulated annealing algorithm and a region search algorithm (ISA-RSA, Method Ⅳ). These methods are compared with a design method based on combination tests using the traversing method (Method Ⅰ) and a design method based on the heuristic optimization algorithm (Method Ⅱ). The results indicate that Method I incurs high design costs with limited effectiveness, while Method II exhibits unstable economic performance and integrated design objectives with fluctuations. Method III is highly dependent on the accuracy of the estimated model and performs poorly in optimizing acceleration time. However, Method Ⅳ, with low design costs, demonstrates remarkable optimization ability to solve high nonlinearity problems and exhibits a high probability of converging to the area near the globally optimal solution. This paper also aims to provide a direct solution to high design cost and highly nonlinear design objective problems in other engineering fields.

Multiobjective optimization of a staggered-rotor octocopter design based on a surrogate model

When designing a novel double-layer staggered-rotor octocopter with improved aerodynamic performance, the aerodynamic performance and structural parameters will have a complex coupling relationship that should be considered in the overall design process. A surrogate-model-based multiobjective optimization method is proposed in this study to optimize novel octocopter structural design schemes considering total thrust, the weight of the propeller and fuselage, the storage volume, and the fuselage volume. This approximation and optimization approach effectively reduces the cost of a large amount of computational fluid dynamics (CFD) calculations in octocopter design and provides a global prediction of octocopter performance. According to the verified optimal solution through CFD simulation, we can see that the surrogate model offers excellent predictive ability, and the prediction accuracy of thrust exceeds 95%. Compared with the initial optimum data, the optimal solution calculated from the optimization could generate 76.74% more thrust, the objective function y is improved by 11.48%, and the objective function a is improved by 322.06%. These results show that the aerodynamic/structural parameter optimization design method considering the influence of aerodynamic interference for multirotor aircraft proposed in this paper is feasible and exhibits good performance. The methodology proposed in this work could provide guidelines for structural parameter design optimization for double-deck multiple-rotor aircraft design at the preliminary design stage, as well as copter structural design considering multiple-rotor interference effects.

A Misalignment-Insensitive Hybrid IPT System with Constant Current Output Based on Parameter Optimization

High misalignment-insensitive capacity is of great importance for inductive power transfer (IPT) systems. A hybrid topology based on a parameter optimization design method is presented to obtain constant current output regardless of the coupling and load. DDQ coils are employed to protect against system key parameter changes, and a particle swarm optimization (PSO) method has been presented to achieve a nearly constant current output without using complex control schemes. A hybrid IPT system using DDQ coils has been built. The experimental results verify that the current fluctuation is within 5% when the load varies from 5 Ω to 10 Ω within 50% misalignment of the coupling pads. Moreover, the maximum system DC–DC efficiency is up to 91%.

Resonant wireless charging scheme

In order to reduce the number of switching devices and passive components in the hybrid topology charging system based on resonant power transmission technology, and simplify the control strategy of primary and secondary sides, a hybrid self switching resonant topology based on LCL-LCL/S is proposed. The structure does not need primary and secondary side communication and adds any passive components, and only changes the topology network through the self switching operation of LCL structure can be realized constant current and constant voltage switching of wireless charging system. Then, according to the characteristics of battery charging curve, resonant current threshold and voltage jump threshold, a parameter optimization design method for hybrid resonant topology network is proposed, which can avoid the parameter uncertainty caused by the limitation of empirical selection of resonant network parameters, and provide theoretical basis for parameter selection. In the constant current and constant voltage mode, the input impedance is pure resistance, and the zero phase angle(ZPA) is between the input current and the voltage. The experimental results show that the hybrid self switching wireless charging system with optimized resonant network parameters has better constant current and constant voltage output characteristics. The system realizes ZPA and constant frequency soft switching characteristics, which meets the requirements of constant current and constant voltage charging.

Research on Geometric Parameters Optimization of Fixed Frog Based on Particle Swarm Optimization Algorithm

In this paper, to improve the wheel/rail dynamic performance of the vehicle passing through the fixed frog area and improve the service life of the fixed frog, a geometric parameter optimization design method of the fixed frog area is proposed using particle swarm optimization (PSO). Based on the variable section rail profile interpolation algorithm and wheel/rail contact solution algorithm, the wheel/rail contact characteristics of the fixed frog area are analyzed. Then, the vehicle-fixed frog dynamic model is built using a MATLAB/Simulink platform to complete the dynamic calculation and analysis of the rail vehicle passing through the fixed frog area. Finally, based on the wheel/rail contact characteristics of the fixed frog area, and take wheel/rail forces as the optimization goal, the optimization design method for the wing rail lifting value and the nose rail height of the fixed frog area is proposed. The comparative analysis shows that the wheel/rail dynamic performance in the fixed frog area has been greatly improved after optimization, which verifies the feasibility of the optimization strategy.

Robust Control and Optimization Method for Single-Phase Grid-Connected Inverters Based on All-Pass-Filter Phase-Locked Loop in Weak Grid

In a distributed generation system, the all-pass-filter phase-locked loop (APF-PLL) is a commonly used method for grid synchronization. However, the coupling effect between APF-PLL and current control loop increases the risk of oscillation instability for the inverter in the weak grid. At present, there are few effective methods to solve the adverse effect of APF-PLL on the inverter-grid interconnection system in the weak grid. Therefore, a small-signal impedance model of the inverter considering the dual d-q frame brought by APF-PLL is first established. Then the reason for the inverter instability caused by APF-PLL in the weak grid is analyzed. Subsequently, an impedance reshaping method based on a modified first-order filter PLL with a complex coefficient filter (CCF-MFOF-PLL) and its parameter optimization design method are proposed. Finally, the experimental results verify that the proposed method widens the stable range of the inverter and ensures the stable operation of the inverter even with the large grid impedance.

A novel installation parameter optimization design method of forming tool for screw rotor

Characterized by a complex contour profile involving arc, cycloid, and involute, the screw rotor is usually manufactured by a forming tool. The finished surface quality and efficiency of the screw rotor are determined by the cutting performance of the forming tool. However, the machining performance of the forming tool is closely related to the structure shape of cutting edge, which is then determined by the installation parameters of the forming tool. Therefore, to make the cutting performance of forming tool controllable, it is essential to investigate the relationship between the cutting performance of the forming tool and its installation parameters at the design stage. In this paper, a novel installation parameter optimization design method of forming tool for screw rotor is presented. A parametric optimization program is designed to finalize the range of installation parameters satisfying the spatial meshing relation and machining equipment parameters. The profile characteristics of forming tool under different center distances and mounting angles have been investigated. For validation, several screw rotors were ground in experiments and the resulted profile errors were analyzed. The results show that the cost of precision grinding of screw rotor can be significantly reduced, without compromise of machining quality. As such, the proposed design method could serve as a promising platform to facilitate screw rotor manufacture.

Experimental investigation and optimization of co-axial ring + core dual beam laser welding parameters for SUS301 stainless steel sheet

ABSTRACT In this paper, a new type of laser beam (co-axial ring beam + core beam) is introduced to weld SUS301 stainless steel with thickness of 0.6 mm, mainly expounds the influence of ring laser on welding deformation and mechanical properties. The ring laser power (RLP), core laser power (CLP) and welding speed (WS) are identified by the response surface method. The maximum deformation after welding, dimensions of the top and bottom of the weld, and the hardness are considered to be the process response. In the process of welding parameter optimization, the multiple regression model of process parameters and response is established by using Box–Behnken parameter optimization design method. Through the significance evaluation, it is found that the accuracy of the regression model is better. Then, the welding process parameters that meet the welding performance and minimum deformation are confirmed by the response surface optimization method. The optimal process parameters are verified by experiments.

Study on Seismic Response and Parameter Influence in a Transformer–Bushing with Inerter Isolation System

In this paper, a mechanical model of a transformer–bushing with an inerter isolation system (IIS) is established. An IIS is composed of an inerter element, a damping element, and a spring element connected in parallel between the same two terminals. Vibration control equations and frequency response functions are also established. The influence of parameters on IIS, including inerter–mass ratio, damping ratio, and frequency ratio, was studied. In the extremum condition that represents the most efficient parameter set of inerter–mass ratio and damping ratio for relative displacement response ratio, an optimal design method was developed by exploiting a performance demand. Finally, the seismic response of the transformer–bushing with IIS was carried out to verify the isolation performance of IIS. The research shows that the equivalent mass coefficient and damping coefficient of IIS can be amplified by an inerter element and the inerter–mass ratio and damping ratio are reduced simultaneously under the conditions of meeting the performance demand after parameter optimization. Meanwhile, the parameter optimization design method proved to be effective for meeting the target demand of the relative displacement response of the bushing and tank, while base shear force and isolation displacement were reduced simultaneously. Based on the results from a response history analysis under ground motion records, IISs can significantly suppress the resonance response of a structure and the continuous vibration response in the stable state. The peak displacement can be reduced by 50% compared with a traditional isolation system.

Efficiency Optimization Design of L-LLC Resonant Bidirectional DC-DC Converter

The new type of L-LLC resonant bidirectional DC-DC converter (L-LLC-BDC) has merits of high efficiency, high-power density and wide gain and power ranges, and it is suitable for energy interface between energy storage systems and DC micro grid. However, the resonances are sensitive to the parasitic parameters, which will deteriorate the efficiency. This paper investigates the intrinsic mechanism of parasitic parameters on the L-LLC-BDC operating principle and working characteristics based on the analysis of working modes and resonance tank. By taking the oscillation of parasitic parameters produced in the stage for the freewheeling stage into consideration, a parameter optimization method is proposed to reduce the resonant current oscillation while maintaining the characteristic of the natural soft switching. The experiment results not only validated the proposed parameter optimization design method, but also testified to the improvement of the efficiency through the minimization of the conduction and switching loss.

Robust Control of Electric Tail Reduction System: Uncertainty and Performance Index

The electric tail reduction system of the unmanned helicopter contains uncertainty. To solve this problem, a constraint-following approach was applied to design a novel robust control for uncertain mechanical systems. The dynamic model of the uncertain electric tail reduction system was established by combining the load of the electric tail rotor and the flight state of the helicopter. Based on the Udwadia–Kalaba theory, a robust constraint following the control method was proposed to deal with the uncertainty of the system. In addition, to balance the steady-state performance and control cost of the system, a control parameter optimization design method was proposed to minimize the performance index. Furthermore, the unique solution of the optimal parameter can be obtained. Compared with the LQR control method, the effectiveness of the optimization method of robust constraint following control was verified.