Current Controller Parameters Research Articles

Voltage Stability and Transient Symmetrical Fault Current Control of Voltage-Controlled MMCs

This paper presents a design-oriented analysis on the voltage stability and the transient fault current limitation of voltage-controlled modular multilevel converter (MMC) with L-filters. First, a dual-loop voltage control based on the L-filter plant is systematically designed, where the upper limits of controller parameters to ensure the small-signal stability are identified. Then, considering the transient current limitation during faults, the lower boundaries of inner current controller parameters are derived. Within the region of allowed controller parameters, the optimization is further made to minimize the closed-loop output impedance of MMC, which enhances the output voltage stiffness against the load current disturbance. Lastly, time-domain simulations corroborate the theoretical analysis.

A self-adaptive multi-population differential evolution algorithm

Differential evolution (DE) is an efficient population-based search algorithm for solving numerical optimization problems. However, the performance of DE is very sensitive to the choice of mutation strategies and their associated control parameters. In this paper, we propose a self-adaptive multi-population differential evolution algorithm, called SAMDE. The population is randomly divided into three equally sized sub-populations, each with different mutation strategies. At the end of each generation, all sub-populations are updated independently and recombined. Each sub-population uses an adaptive mechanism for selecting how current generation control parameters are generated. An improved mutation strategy, “rand assemble/1”, is proposed, its base vector is composed proportionally of three randomly selected individuals. The performance of SAMDE is evaluated on the suite of CEC 2005 benchmark functions. A comparative study is carried out with other state-of-the-art optimization techniques. The results show that SAMDE has a competitive performance compared to several other efficient DE variants.

Phase-related noise characteristics of 780 nm band single-frequency lasers used in the cold atomic clock**Project supported by the National Natural Science Foundation of China (Grant Nos. 61875214, 61535014, and 61775225) and Scientific Innovation Fund of Chinese Academy of Sciences (Grant No. CXJJ-17S010).

We propose a method to directly measure phase-related noise characteristics of single-frequency lasers in the 728–980 nm band based on a 120° phase difference interferometer. Differential phase information of the laser under test is demodulated via the interferometer. Other parameters related to the phase noise characteristics such as linewidth at different observation time, phase/frequency noise, power spectrum density of phase/frequency fluctuation, and Allan deviation are further obtained. Frequency noise as low as 1 Hz2/Hz can be measured using our system. Then the phase-related noise characteristics of two commercial lasers frequently used in cold atomic clocks are studied systematically by the method. Furthermore, several influencing factors and their relative evolution laws are also revealed, such as the pump current and frequency-locking control parameters. This would help to optimize the laser performance, select laser sources, and evaluate the system performance for cold atomic physics applications.

Systematic controller design for digitally controlled LCL-type grid-connected inverter with grid-current-feedback active damping

An LCL filter is commonly used in grid-connected inverter to attenuate the switching harmonics; nevertheless, the stability problems will arise in the grid current control if the resonance of LCL filter is not properly damped. High pass filter-based grid current feedback active damping is an effective solution to solve the aforesaid problem. However, for systems with digital control, the system may exhibit non-minimum phase system characteristics due to the control delay effect, which will affect the system stability. Moreover, the frequency responses of current controller parameters and active damping parameters are coupled. Therefore, to ensure the system stability and good dynamic performance, the current controller parameters and active damping parameters should be designed together, considering the control delay effect. For this issue, a systematic controller design method is proposed for the digitally controlled LCL-type grid-connected inverter with grid-current-feedback active damping. With the proposed method, the satisfactory regions of the control parameters for satisfying the system specifications can be obtained, from which the proper control parameters can be easily and quickly picked out, without the trial and error. Finally, the proposed design method is verified by the experiment.

Analysis and design of genetic algorithm-based cascade control strategy for improving the dynamic performance of interleaved DC–DC SEPIC PFC converter

Switched-mode power supplies used for powering new generation devices like microprocessors, utility grids and electric vehicles need to operate with faster dynamic response. This paper proposes cascade control technique using genetic algorithm to obtain the optimal proportional integral outer voltage and inner current controller parameters of interleaved DC–DC single-ended primary inductance converter for power factor correction in SMPS with fast dynamic response. The state space model of the interleaved DC–DC SEPIC converter is derived using state space averaging technique. The system is of higher order, and hence, the reduced-order model of the interleaved DC–DC SEPIC converter is realized using Hankel matrix approach to reduce the computational complexity in controller design. The optimal controller parameters are then obtained for the reduced-order system using genetic algorithm for improving the dynamic performance of the system. The performance of the closed-loop system is analyzed in terms of input power factor, % total harmonic distortion of source current, % efficiency and % load voltage regulation for variations in the line, load and reference voltage using Matlab/Simulink software tool. A prototype of the converter controlled by TMS320C2000™ microcontroller for an output power of 200 W is tested and validated with the simulation results.

Modeling and Parameter Design of Voltage-Controlled Inverters Based on Discrete Control

Grid-connected inverters are widely used to interface renewable energy and energy storage resources into the grid. Voltage-controlled inverters have attracted more and more attention due to their grid-friendly characteristics. The mathematical models of the voltage and current loops are developed in this paper, considering especially the discrete control delay caused by calculation and modulation. In order to suppress the resonance peak in the current loop, the frequency characteristics of the current loop are analyzed in detail. The optimum design flow of the current controller and voltage controller parameters are presented based on numerical analysis, and the stability, dynamic performance and the resonance peak suppression in voltage loop are also considered. Finally, the validity of the mathematical model and the effectiveness of the controller parameters design method are verified by simulation and experimental results.

Quantum-Behaved Lightning Search Algorithm to Improve Indirect Field-Oriented Fuzzy-PI Control for IM Drive

The main objective of this study is to develop a quantum-behaved lightening search algorithm (QLSA) to improve the indirect field-oriented fuzzy-proportional-integral (PI) controller technique to control a three-phase induction motor (TIM) drive. The generated adaptive PI current control parameters and fuzzy membership functions are carried to design induction motor drive speed controller to minimize the fitness function formulated by QLSA. An optimal QLSA-based indirect field-oriented control (QLSA-IFOC) fitness function is used to reduce the mean absolute error of the rotor speed to improve the performance of the TIM with varying speed and mechanical load. Results obtained from the QLSA-IFOC are compared with those obtained through lightening search algorithm, gravitational search algorithm, backtracking search algorithm, and particle swarm optimization to validate the developed controller. The optimization results of objective functions in terms of box plots and iterations show that the QLSA algorithm outperforms the other optimization algorithms. Moreover, the QLSA-IFOC controller performed well in all tests in terms of transient response. The developed controller also minimizes overshoot, increases damping capability, and reduces the root-mean-square error, as well as standard deviation under sudden change of speed and mechanical loads. A comparative analysis is performed between simulation and experimental results to justify the efficiency of the developed controller.

An Improved Design of Current Controller for <italic>LCL</italic>-Type Grid-Connected Converter to Reduce Negative Effect of PLL in Weak Grid

For three-phase LCL -type grid-connected converter, when it is attached to weak grid, current control interacts with phase-locked loop (PLL) via point of common coupling voltage. Consequently, PLL dynamic might deteriorate grid current control and even result in system instability. However, the conventional design method of current controller neglects the impact of PLL, and therefore, it is hard for the current controller to mitigate the negative effect of PLL. In this paper, an improved design of current controller, i.e., proportional–integral controller and capacitor-current-feedback active damping, is proposed to reduce the negative effect of PLL on current control. First, a small-signal impedance model is developed to analyze the impact of PLL on current control. Then, the effect of current controller parameters on the converter output impedance is analyzed, and a design guideline to improve the current controller parameters is presented. With the improved parameters, in precondition of satisfying system stability margin under both stiff and weak grid, the negative effect of PLL on current control can be effectively mitigated without employing additional control strategies. Furthermore, the current control has a strong robustness against wide-range variation of grid impedance. Finally, the experiment demonstrates the effectiveness of the proposed design method.

Newly Developed Resins More Challenging to Control in Production Plants

Plastics EngineeringVolume 74, Issue 5 p. 48-51 Technical Article Newly Developed Resins More Challenging to Control in Production Plants Developments in resins have opened up a whole new world of design choices, but challenges remain because current quality control parameters only show part of the picture B. Monrabal, B. Monrabal Polymer Char, Valencia, SpainSearch for more papers by this authorA. Ortín, A. Ortín Polymer Char, Valencia, SpainSearch for more papers by this authorP. del Hierro, P. del Hierro Polymer Char, Valencia, SpainSearch for more papers by this author B. Monrabal, B. Monrabal Polymer Char, Valencia, SpainSearch for more papers by this authorA. Ortín, A. Ortín Polymer Char, Valencia, SpainSearch for more papers by this authorP. del Hierro, P. del Hierro Polymer Char, Valencia, SpainSearch for more papers by this author First published: 01 May 2018 https://doi.org/10.1002/j.1941-9635.2018.tb01887.xAboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume74, Issue5May 2018Pages 48-51 RelatedInformation

Impact of df/dt Inertia Control on Doubly Fed Induction Generator Type Wind Turbine

the supplemental df/dt control is the common method for wind power generation to support system inertial response. This paper investigates the impact of the df/dt inertia controller on doubly fed induction generator (DFIG) type wind turbine. The controller is usually a high pass filter. Two parameters which are the gain and the time constant are considered. By constructing the linearized model of DFIG, the impacts of the two parameters of the controller are discussed. It shows that with different phase locked loop (PLL) parameters and current control parameters, different time constants and gains are required to ensure the DFIG stability. The time domain simulation validates the result.

Analysis of the Behavior of Undamped and Unstable High-Frequency Resonance in a DFIG System

As the wind power generation develops, the doubly fed induction generator (DFIG) based wind power system may suffer subsynchronous resonance and high-frequency resonance (HFR) in the series and parallel compensated weak network. The principle and frequency of HFR have been discussed using the Bode diagram as an analysis tool. However, the HFR can be categorized into two different types: undamped HFR (which exists in steady state) and unstable HFR (which eventually results in complete instability and divergence), both of them are not investigated before. Since both the undamped HFR and unstable HFR are critical to the output wind power quality as well as the safe and reliable operation of the DFIG system, it is meaningful to discuss them using the Nyquist criterion from two perspectives: 1) determining either the undamped HFR or the unstable HFR occurs; and 2) estimating the amplitude of the undamped HFR. The influence factors, including the weak network shunt capacitance and the current PI controller parameters, are discussed when estimating the amplitude of the undamped HFR. The experimental and simulation results of a 7.5 kW down-scaled DFIG setup are provided to validate the analysis of the undamped HFR and unstable HFR.

Steady-State Modeling of Modular Multilevel Converter Under Unbalanced Grid Conditions

This paper presents a steady-state model of MMC for the second-order phase voltage ripple prediction under unbalanced conditions, taking the impact of negative-sequence current control into account. From the steady-state model, a circular relationship is found among current and voltage quantities, which can be used to evaluate the magnitudes and initial phase angles of different circulating current components. Moreover, in order to calculate the circulating current in a point-to-point MMC-based HVdc system under unbalanced grid conditions, the derivation of equivalent dc impedance of an MMC is discussed as well. According to the dc impedance model, an MMC inverter can be represented as a series connected R–L–C branch, with its equivalent resistance and capacitance directly related to the circulating current control parameters. Experimental results from a scaled-down three-phase MMC system under an emulated single-line-to-ground fault are provided to support the theoretical analysis and derived model. This new models provides an insight into the impact of different control schemes on the fault characteristics and improves the understanding of the operation of MMC under unbalanced conditions.

Optimized Controller Design for a 12-Pulse Voltage Source Converter Based HVDC System

The paper proposes an optimized controller design scheme for power quality improvement in 12-pulse voltage source converter based high voltage direct current system. The proposed scheme is hybrid combination of golden section search and successive linear search method. The paper aims at reduction of current sensor and optimization of controller. The voltage and current controller parameters are selected for optimization due to its impact on power quality. The proposed algorithm for controller optimizes the objective function which is composed of current harmonic distortion, power factor, and DC voltage ripples. The detailed designs and modeling of the complete system are discussed and its simulation is carried out in MATLAB–Simulink environment. The obtained results are presented to demonstrate the effectiveness of the proposed scheme under different transient conditions such as load perturbation, non-linear load condition, voltage sag condition, and tapped load fault under one phase open condition at both points-of-common coupling.

Overview of DFIG-Based Wind Power System Resonances Under Weak Networks

The wind power generation techniques are continuing to develop and increasing numbers of doubly fed induction generator (DFIG)-based wind power systems are connecting to the on-shore and off-shore grids, local standalone weak networks, and microgrid applications. The impedances of the weak networks are too large to be neglected and require careful attention. Due to the impedance interaction between the weak network and the DFIG system, both subsynchronous resonance (SSR) and high-frequency resonance (HFR) may occur when the DFIG system is connected to the series or parallel compensated weak network. This paper will discuss the SSR and the HFR phenomena based on the impedance modeling of the DFIG system and the weak networks, and the cause of these two resonances will be explained in details. The following factors will be discussed in this paper: 1) transformer configuration; 2) different power scale of DFIG system with different parameters; 3) L or LCL filter adopted in the grid side converter (GSC); 4) rotor speed; 5) current closed-loop controller parameters; and 6) digital control delay. On the basis of the analysis, active damping strategies for HFR using virtual impedance concept will be proposed.

A Novel Data-Driven Method for Simultaneous Performance Assessment and Retuning of PID Controllers

A novel data-driven method for simultaneous performance assessment and retuning PID controllers is presented in this study. The PID tuning problem is cast as a convex approximation problem of a reference model, which makes the resulting closed-loop step response resemble that of a predefined reference model. The proposed data-driven method only requires the current PID controller parameters and a set of closed-loop data with set point changes, while the process model is neither necessary to be known a priori nor to be identified directly. The controller effort limitation, which is closely related to variations of controller actions, is an important concern for controller design. To evaluate PID controller performance subject to control effort limitations, a trade-off curve displaying the integrated squared error against the total squared variation of controller actions is obtained, which can be calculated in a cost efficient way and serves as a useful tool for performance assessment and retuning of PID co...

永久磁石同期電動機の高精度駆動のための電圧飽和を回避し磁気飽和を考慮した電流制御パラメータ決定法

For use as a drive motor in a high precision NC machine tool feed axis, a permanent magnetic synchronous motor (PMSM) requires a highly responsive current control loop. Without consideration of the PMSM electromagnetic characteristics such as voltage saturation and magnetic saturation, the current control loop may be unstable. This paper proposes a method for determination of the PMSM current control parameters providing such high response, while avoiding voltage saturation by inverter output voltage constraint or declination of inductance by magnetic saturation. Experiments were done using two representative PMSMs alone and also using a machine tool. Testing confirmed that the proposed method is effective for achieving a highly responsive current control loop and making the cutting surface smoother.

Experimental research of electro-hydraulic proportional valve of mechatronic control system of automatic gearbox

To control the mechanisms of automobiles, tractors, building and road machines, the mechatronic automatic control systems are commonly used; one of their most important components is the electro-hydraulic proportional valve. Mechatronic systems allow to implement the sophisticated adaptive control algorithms, provide the high quality of functioning processes of controlled mechanisms and significantly increase the efficiency of production processes. The article deals with the experimental research of characteristics of electro-hydraulic proportional valve and the optimization of parameters of its control implemented by the microprocessor controller. Such valves are applied in automatic transmissions for the control of gear shift and working organs. The key diagram of created valve is given; its interaction with mechanisms of mechatronic systems is shown. The system functioning in implementation process of its work algorithm under control of the microprocessor controller is described. The article describes the results of experimental research of the electro-hydraulic proportional valve and technical solutions that allow to improve significantly its performance. The static and transient responses of the valve and its components are obtained. It is found that the form of transient response of proportional solenoid depends on the power source characteristic. With the use of direct current source, the transient response corresponds to aperiodic link, but with the use of controller, it corresponds to oscillatory one. The oscillatory character of transient response is caused by the control action of current controller. Current controller parameters influence the relative overshoot and the delay time of current rise in the proportional solenoid winding. The optimal parameters of current controller settings are defined. Influence of oscillation of control signal on the hysteresis of static response of control mechanism is investigated. Parameters of electro-hydraulic proportional valve that allow to estimate the possibility of its application for the control of working organs of machines are described.

Cascaded proportional–integral–derivative controller parameters tuning for contour following improvement

Most commercial servo systems utilize cascaded proportional–integral–derivative controller due to its simplicity and robustness. Under this control structure, motion performances such as single-axial tracking and multi-axial contour following are completely determined by the controller parameters. In real applications, current loop controller parameters usually remain unchanged while velocity loop and position loop ones should be tuned as the mechanisms including inertia and resonant frequency vary. This article focuses on such cascaded proportional–integral–derivative controller parameters tuning for contour following performance improvement. It first describes the servo system dynamics under the cascaded proportional–integral–derivative control structure and identifies the model parameters via relay feedback technology. Then, the effects of the closed-loop dynamics on contour following are analyzed to gain that the matched axial dynamics is preferable. In order to match the axial dynamics, the controller parameters are tuned loop by loop through setting all the axes to have the same bandwidths. Based on the identified results, feedforward controller parameters including nonlinear coulomb friction compensation are also tuned to further improve the contour following performance. At last, the proposed tuning method is verified through the ellipse and diamond following experiments carried out on an X-Y motion stage. The results show that it can match the axial dynamics effectively and thus reduce the contour error greatly.

유도전동기의 고성능 벡터 제어를 위한 유도전동기 정수 측정

The accuracy of motor parameter measurement is necessary to improve the performance of vector control of an induction motor. The rotor time constant affects the performance of controller and also the resistance and leakage inductance of stator are very important design parameters of current and speed controller. In this paper a new modified motor parameter measurement methods for high performance speed control of vector control of an induction motor are proposed.

The Study of DC Motor Position Controller Parameter Setting and Simulation

Classic setting method not only process trival, but also can't ensure that the controller you get is optimal. In order to obtain satisfactory system performance, in this paper, In this paper, the genetic algorithm is introduced to the dc motor optimal position tracking system control problem. By using it to global optimization of the controller parameters, and setting the current, speed and position controller parameters. The simulation results: PID controller designed by using genetic algorithm can make the response of control system tracking faster and no overshoot,make sure that the system control effect based on the stability and improve the system performance and achieve the actual process requirements. The simulation results verify that the proposed method is effectiveness.