Load Disturbance Conditions Research Articles

Modeling of dynamic characteristics and μ-synthesis control of piezoelectric positioning platform

Abstract The dynamic hysteresis nonlinearity and various uncertainties of the piezoelectric positioning platform are critical factors limiting its high-precision applications. To address this, the dynamic characteristics of the piezoelectric positioning platform under various loads are identified based on the linearization of the Prandtl-Ishlinskii inverse model. The inverse compensation error and load disturbances are attributed to model uncertainties, which are modeled in the frequency domain. A μ-synthesis controller is designed to improve the tracking accuracy of the piezoelectric positioning platform under uncertainty disturbances. Experimental results indicate that with the μ-synthesis controller, the piezoelectric positioning platform achieves a relative error (RE) of less than 2.71% when unloaded. The RE is less than 6.03% for load disturbances of 100g, 200g, and 300g, respectively. These results demonstrate that the designed controller meets the high-precision positioning performance requirements under various load disturbance conditions.

Fractional-PID and Its Parameter Optimization for Pumped Storage Units Considering the Complicated Conduit System

Speed governing control is significant in ensuring the stable operation of pumped storage units. In this study, a state-space equation mathematical model of the pumped storage governing system considering the complex hydraulic pipeline structure of the pumped storage plant is proposed to describe the system’s dynamic behaviors under small disturbance conditions. Considering the frequent operating condition transitions and the complicated nonlinear dynamic characteristics of the pumped storage units, the fractional-order PID (FOPID) scheme that possesses a higher degree of control freedom than the traditional PID scheme is discussed in detail. To optimize the control parameters of the unit governor, an improved gravitational search algorithm (IGSA) that combines the basic searching mechanisms of the gravitational search algorithm and chaotic search, elastic sphere boundary treatment, and elite guidance strategy is developed. Comparative studies have been carried out under frequency and load disturbance conditions. Simulation results indicate that the control performance of FOPID is better than that of PID under diverse operating conditions and the proposed IGSA has satisfactory parameter optimization capability.

Adaptive Gain Tuning Rule for Nonlinear Sliding-Mode Speed Control of Encoderless Three-Phase Permanent Magnet Assisted Synchronous Motor

In this paper, an adaptive gain tuning rule is designed for the nonlinear sliding mode speed control (NSMSC) in order to enhance the dynamic performance and the robustness of the permanent magnet assisted synchronous reluctance motor (PMa-SynRM) with considering the parameter uncertainties. A nonlinear sliding surface whose parameters are altering with time is designed at first. The proposed NSMSC can minimize the settling time without any overshoot via utilizing a low damping ratio at starting along with a high damping ratio as the output approaches the target set-point. In addition, it eliminates the problem of the singularity with the upper bound of an uncertain term that is hard to be measured practically as well as ensures a rapid convergence in finite time, through employing a simple adaptation law. Moreover, for enhancing the system efficiency throughout the constant torque region, the control system utilizes the maximum torque per ampere technique. The nonlinear sliding surface stability is assured via employing Lyapunov stability theory. Furthermore, a simple sliding mode estimator is employed for estimating the system uncertainties. The stability analysis and the experimental results indicate the effectiveness along with feasibility of the proposed speed estimation and the NSMSC approach for a 1.1-kW PMa-SynRM under different speed references, electrical and mechanical parameters disparities, and load disturbance conditions.

Oscillation Damping Neuro-Based Controllers Augmented Solar Energy Penetration Management of Power System Stability

The appropriate design of the power oscillation damping controllers guarantees that distributed energy resources and sustainable smart grids deliver excellent service subjected to big data for planned maintenance of renewable energy. Therefore, the main target of this study is to suppress the low-frequency oscillations due to disruptive faults and heavy load disturbance conditions. The considered power system comprises two interconnected hydroelectric areas with heavy solar energy penetrations, severely impacting the power system stabilizers. When associated with appropriate controllers, FACTs technology such as the static synchronous series compensator provides efficient dampening of the adverse power frequency oscillations. First, a two-area power system with heavy solar energy penetration is implemented. Second, two neuro-based controllers are developed. The first controller is constructed with an optimized particle swarm optimization (PSO) based neural network, while the second is created with the adaptive neuro-fuzzy. An energy management approach is developed to lessen the risky impact of the injected solar energy upon the rotor speed deviations of the synchronous generator. The obtained results are impartially compared with a lead-lag compensator. The obtained results demonstrate that the developed PSO-based neural network controller outperforms the other controllers in terms of execution time and the system performance indices. Solar energy penetrations temporarily influence the electrical power produced by the synchronous generators, which slow down for uncomfortably lengthy intervals for solar energy injection greater than 0.5 pu.

Centralised fractional order LQI controller design for quadruple tank process — An optimisation approach

In this paper, a centralised Fractional Order Linear Quadratic Integral (FOLQI) controller is proposed for highly interacting Multi Input Multi Output (MIMO) system to reject the load disturbance conditions. An optimisation problem to minimise the control effort as an objective function is formulated in addition to meet the desired time domain inequality constraints. The parameters of the FOLQI controller are obtained by using sequential quadratic programming optimisation approach. For illustration, the quadruple tank process is considered as a case study which exhibits both minimum and non-minimum phase characteristics. To show the performance of the FOLQI controller, the simulation is performed under disturbance and parameter uncertainty conditions. The performance indices such as maximum peak overshoot, settling time and steady state error are computed for FOLQI controller. To show the superiority of FOLQI controller, these indices are compared with the responses obtained using the existing Integer Order Linear Quadratic Integral (IOLQI) and Linear Active Disturbance Rejection (LADR) controllers.

Forced vibration analysis model for pumped storage power station based on the 1D–3D coupling and pipe walls vibration

AbstractHydraulic vibration is a common phenomenon in pumped storage power stations (PSPS) and hydropower plants. Evaluating the performance of the PSPS and water conveyance system under the hydraulic vibration condition is significant for the safety of the electric power and the PSPS system. In this study, the one‐dimensional (1D) and three‐dimensional (3D) coupling model for the entire PSPS system is established based on the open‐source software OpenFOAM and in‐house C++ codes. The coupling data exchange is realized by writing and reading files. The coupling model is validated by comparing the results with the pure 1D method under small load disturbance conditions. The forced vibration source is modeled by the pipe walls vibration method in the 3D region, and the 1D method takes charge of other parts in the PSPS system. The combination of the pipe walls vibration and 1D–3D coupling could fully consider the incident and reflected characteristics of the pressure waves. The established model could evaluate the overall performance of the PSPS system under forced vibration. Sensitive analysis of the vibration magnitude is carried out, and the results are consistent with the theoretical analysis, demonstrating that the established model is applicable for the forced vibration analysis.

Modelling And Analysis Of Pvsc Type Buck Buck-Boost Dc-Dc Converter

In the era of modern industrial development, power electronics equipment has been developed aggressively and brought dc system again in power utilization to use clean energy resources like solar array, fuel cell, wind generator, etc. Since the past decade, power electronics equipment has become very popular; hence, the switch-mode converter requirement is increasing rapidly day by day in applications like communication power supply, space crafts, hybrid electric vehicles, micro-grid and nano-grids. Among the various available configurations of converters, Multi-Input DC/DC converters became more and more popular in power electronics field, especially, for provide interface of various renewable energy sources and deliver regulated power to several loads. In this article, a PVSC type Buck Buck-Boost Dual-Input DC- DC Converter (DIDC) is designed and modelled for DC grid application. The proposed converter is driven with two renewable energy sources PV cell and a battery having different amplitudes which can able to deliver the power from source to load individually or simultaneously. DIDC tropology is simply configured with two passive elements L, C, diodes D1 D2 and switches S1 , S2. The Dual-Input DC-DC Converter suitability is validated by carrying out simulations in different modes of operation. The de-centralized PID controller is designed for voltage and current loop controller to ensure the DC output voltage of 48 V, load current of 4.8 A and power of 230W. The Stability of the closed-loop converter is also verified under all possible source and load disturbance conditions. The simulations and analysis of the proposed converter are carried out using MATLAB and PSIM software.

Control of twin-double pendulum lower extremity exoskeleton system with fuzzy logic control method

In this article, a two degree of freedom lower-limb exoskeleton (LLE) design control is developed to reduce the fatigue level of healthy people and increase their load-carrying capacity. The LLE robot system is designed by comparing it to the twin-double pendulum system. One of the twin pendulums models is the human leg (with a knee and hip joint), and the other twin pendulum model is the exoskeleton robot. The movement of the human knee and hip joints in a walking pattern is recreated with a joint angle generator and applied to the joints with the help of a linear motor. The exoskeleton robot is provided to follow the movements of the leg with the help of a fuzzy controller. The control simulation with the mathematical model of the twin-double pendulum system and the fuzzy logic method was made using the MATLAB/Simulink program. The system response was analyzed and graphed for two different limb sizes (45 cm and 50 cm) and three different load conditions (no load, 25 Nm and 75 Nm). The maximum tracking errors are 3.2105° and 3.4730° for the hip and knee joint, respectively, with a 75 Nm load disturbance condition. These tracking error values can be interpreted as very low with high tracking success. The FL controller is robust to load changing and limb size-changing factors, and for this reason, it was suitable for use in LLEs.

Implementation of Optimization-Based PI Controller Tuning for Non-Ideal Differential Boost Inverter

The demand for renewable energy to sustain today’s vulnerability towards depleting fossil fuels is a crucial agenda for research. Various inverter topologies have been proposed to convert renewable sources into a usable form. But output THD, additional filtering components at line frequency (leading to bulky circuitry), lower efficiency, etc., are some of the limitations faced in all those topologies. This paper aims to change a voltage source inverter’s traditional behavior, which generates lesser output voltage with higher THD. The paper proposes a closed-loop non-ideal differential boost inverter (DBI) employing a PI controller. The optimization techniques such as, genetic algorithm (GA) and bacterial foraging optimization algorithm (BFOA) are incorporated to accentuate the PI controller’s performance to produce a better response during line and load disturbance conditions with reduced THD. DBI performance is evaluated on a laboratory prototype with different loading conditions. A comparison between the algorithms and the previous topologies from the literature survey has also been provided to validate this research’s claims. This paper’s required simulation study is carried out using MATLAB, and real-time validation is carried out using dSPACE 1104 with sampling time of one $\mu \text{s}$ .

Load Disturbance Conditions for Current Error Feedback and Past Error Feedforward State-Feedback Iterative Learning Control

Iterative learning control is a controlling tool developed to overcome periodic disturbances acting on repetitive systems. State-feedback ILC controller was designed based on the use of the small gain theorem. Stability conditions were reported in the case of past error and current error feedback schemes based on Singular values. Disturbances acting on the load of the system were reported for the case of past error feedforward only which kept the investigation of the current error feedback as an open question. This paper develops a comparison between the past error feedforward and current error feedback schemes disturbance conditions in singular values. As a result, the conditions found highly support the use of the past error over the current error feedback.

Bivariate grid-connection speed control of hydraulic wind turbines

The requirement for An electrical grid-connected wind turbine is that the synchronous generator speed is stable within a required speed range for the electrical grid. In this paper, a hydraulic wind turbine (HWT) system is considered, and the working principle and working conditions of the HWT are introduced. A novel speed control method is proposed in this paper, using both a proportional flow control valve and a variable displacement motor, which are adjusted in combination to control the speed of the HWT. By establishing a state space model of the HWT and solving the nonlinear system with a feedback linearization method, a bivariate tracking controller is constructed to realize accurate speed control under fluctuating wind speed and the load disturbance conditions. The effectiveness of the control method is verified by simulation, but experimental results highlight problems with the method. The theoretical controller is simplified to reduce sensitivity to measurement noise and modeling error. The control effect has been improved to some extent, but it is limited. Based on these results, combined with the sliding mode variable structure control method and the feedback linearization method to solve the problem of measurement noise and modeling error, and the effectiveness of the control law is finally verified experimentally. It lays a theoretical foundation for the practical application of HWT.

Parameter optimisation research for hydraulic turbine regulating system based on CGABC algorithm

Artificial bee colony (ABC) algorithm is regularly taken in the parameter optimisation of the hydraulic turbine regulating system (HTRS). The chaotic and global artificial bee colony (CGABC) algorithm is proposed to overcome the slow convergence speed and low convergence precision that existed in standard ABC algorithm. Among them, global optimal is used to enhance the global exploration ability, and chaos optimisation is adopted to increase the diversity of bee colony. The simulation results show that compared with fuzzy strategy, ZN, DE and ABC algorithm, the proposed CGABC algorithm significantly improves the dynamic transition process of HTRS. Simultaneously, the simulation experiment is carried out on HTRS with different governor parameters and controlled parameters when it is under the frequency and load disturbance condition. The results show that the dynamic characteristics and robustness is determined by the parameter selection, and the appropriate combination of parameters allows HTRS to achieve optimal dynamic performance and robustness.

Parameter optimisation research for hydraulic turbine regulating system based on CGABC algorithm

Artificial bee colony (ABC) algorithm is regularly taken in the parameter optimisation of the hydraulic turbine regulating system (HTRS). The chaotic and global artificial bee colony (CGABC) algorithm is proposed to overcome the slow convergence speed and low convergence precision that existed in standard ABC algorithm. Among them, global optimal is used to enhance the global exploration ability, and chaos optimisation is adopted to increase the diversity of bee colony. The simulation results show that compared with fuzzy strategy, ZN, DE and ABC algorithm, the proposed CGABC algorithm significantly improves the dynamic transition process of HTRS. Simultaneously, the simulation experiment is carried out on HTRS with different governor parameters and controlled parameters when it is under the frequency and load disturbance condition. The results show that the dynamic characteristics and robustness is determined by the parameter selection, and the appropriate combination of parameters allows HTRS to achieve optimal dynamic performance and robustness.

A New Three-Phase Multi-Level Asymmetrical Inverter With Optimum Hardware Components

In this article, a novel three-phase asymmetrical multilevel inverter is presented. The proposed inverter is designed with an optimal hardware components to generate three-phase nineteen output voltage levels. The proposed inverter exhibits various advantages like a suitable output voltage waveform with improved power quality, lower total harmonic distortion (THD), and more moderate complexity, reduction in cost, reduced power losses, and improved efficiency. A comparison of the proposed topology in terms of several parameters with existing methods illustrates its merits and features. The proposed inverter tested with steady-state and dynamic load disturbances. Various experimental results are included in this article to validate the performance of the proposed inverter during various extremities. In addition, a detailed comparison is tabulated between simulation and experimental results graphically. The proposed inverter has been stable even during load disturbance conditions. The simulation and feasibility model are verified using a prototype model.

Optimised power control and balance scheme for the output parallel dual‐active‐bridge DC‐DC converters in power electronic traction transformer

In order to achieve a comprehensive performance optimisation consisting of transmission power balance, high efficiency, and fast dynamic response for the output parallel dual-active-bridge (DAB) dc–dc converters in power electronic traction transformer, an optimised power control and balance scheme based on extended phase-shift (OPCB-EPS) control is proposed in this study. By combining current stress-optimised calculation with EPS control, the current stress of converters can be reduced significantly and the efficiency can be further improved. In addition, the desired transmission power of DAB converters is estimated on-line by introducing the virtual voltage component to enhance the dynamic response of the output voltage under the input voltage fluctuation and the load disturbance conditions. Meanwhile, the proposed OPCB-EPS scheme can realise the transmission power balance over the whole power range. Finally, a scale-down prototype of DAB dc–dc converters consisting of three cells is developed to compare the performance of the current stress optimised with dual phase-shift (CSO-DPS), current stress optimised with EPS and proposed OPCB-EPS schemes. The comparative experimental results have verified the excellent performance of OPCB-EPS scheme and the theoretical analysis in this work.

Adaptive Gains Control Scheme for PMSG-Based Wind Power Plant to Provide Voltage Regulation Service

High-penetration wind power will count towards a significant portion of future power grid. This significant role requires wind turbine generators (WTGs) to contribute to voltage and reactive power support. The maximum reactive power capacity (MRPC) of a WTG depends on its current input wind speed, so that the reactive power regulating ability of the WTG itself and adjacent WTGs are not necessarily identical due to the variable wind speed and the wake effect. This paper proposes an adaptive gains control scheme (AGCS) for a permanent magnet synchronous generator (PMSG)-based wind power plant (WPP) to provide a voltage regulation service that can enhance the voltage-support capability under load disturbance and various wind conditions. The droop gains of the voltage controller for PMSGs are spatially and temporally dependent variables and adjusted adaptively depending on the MRPC which are a function of the current variable wind speed. Thus, WTGs with lower input wind speed can provide greater reactive power capability. The proposed AGCS is demonstrated by using a PSCAD/EMTDC simulator. It can be concluded that, compared with the conventional fixed-gains control scheme (FGCS), the proposed method can effectively improve the voltage-support capacity while ensuring stable operation of all PMSGs in WPP, especially under high wind speed conditions.

Comperative Performance Analysis of PMSM Drive Using MPSO and ACO Techniques

<p>This work proposes an optimization algorithm to control speed of a permanent magnet synchronous motor (PMSM) during starting and speed reversal of motor, as well as during load disturbance conditions. The objective is to minimize the integral absolute control error of the PMSM shaft speed to achieve fast and accurate speed response under load disturbance and speed reversal conditions. The maximum overshoot, peak time, settling time and rise time of the motor is also minimized to obtain efficient transient speed response. Optimum speed control of PMSM is obtained with the aid of a PID speed controller. Modified Particle Swarm Optimization (MPSO) and Ant Colony Optimization (ACO) techniques has been employed for tuning of the PID speed controller, to determine its gain coefficients (proportional, integral and derivative). Simulation results demonstrate that with use of MPSO and ACO techniques improved control performance of PMSM can be achieved in comparison to the classical Ziegler-Nichols (Z-N) method of PID tuning.</p>

Model Predictive Control With Power Self-Balancing of the Output Parallel DAB DC–DC Converters in Power Electronic Traction Transformer

This paper focuses on the output parallel dual-active-bridge (DAB) dc–dc converters in power electronic traction transformers. A model predictive control with current-stress-optimized (MPC-CSO) scheme based on dual-phase-shift (DPS) control is proposed to improve the dynamic performance, balance the transmission power, and realize the current-stress optimization. The dynamic behavior of output voltage in the next horizon is predicted accurately under the input voltage fluctuation and load disturbance conditions by developing the prediction model. In addition, the proposed MPC-CSO scheme can track the output voltage with the desired value directly with no overshoot during the start-up process. Combining the MPC and CSO scheme, the fast dynamic response and high-efficiency performance of DAB converters can be achieved simultaneously, and the transmission power of each DAB cell can be self-balanced. Finally, three control schemes consisting of traditional voltage closed-loop control with single phase shift, traditional CSO control with DPS, and MPC-CSO with DPS schemes are compared in a scale-down three DAB dc–dc converter cells experimental prototype by using TMS320F28335+FPGA_6SLX45 as core controller. Extensive experimental results have verified the excellent performance of the proposed MPC-CSO scheme and associated analysis in this paper.

Robustness and load disturbance conditions for state based iterative learning control

SummaryRobust conditions and load disturbance limitations are developed for the design of iterative learning control laws for linear dynamics for two commonly used schemes. Many industrial applications encounter periodic disturbances acting on the input of a system operating under repetitive control, which can be represented by a time delay model whose output is applied to the system input in the mathematical representation of the controlled dynamics. The design isolates the disturbance system and defines the overall transfer function around the delay model. Then, the small gain theorem can be used to develop conditions for disturbance accommodation and error convergence of the repetitive control scheme. A simulation case study to support the new results is given, where the model used has been developed by frequency response tests on a gantry robot and is a necessary step before experimental verification.

Stability and Performance Analysis of ANFIS Tuned PID Based Speed Controller for Brushless DC Motor

In this paper, stability and performance analysis of Adaptive Neuro-Fuzzy Inference System (ANFIS) tuned Proportional Integral Derivative (PID) speed controller has been presented for Brushless DC motor. The stability of the proposed controller is examined using Lyapunov and Nyquist stability criterion. The performance of the proposed controller is analyzed for a step change in speed input and sudden load disturbance conditions and also compared with fuzzy PID, super twisting sliding mode control, and PID controllers. Sensitivity of the proposed controller is analyzed with parameter variation in inertia, permanent magnet flux, resistance and inductance of the motor. From the results, it is evident that the proposed controller is more stable and outperforms the other considered controllers in all performance aspects. Keywords: ANFIS, BLDC motor, fuzzy PID, lyapunov stability, nyquist stability, PID, super twisting sliding mode controller.