Sliding Mode Based Droop Control Strategies for Parallel-Connected Inverters in Railway Vehicles

Sliding mode control strategies are well known for ensuring robustness of the system with respect to disturbance and model uncertainties. For continuous-time plants, they achieve this property by confining the system state to a particular hyperplane in the state space. Contrary to this, discrete-time sliding mode control (DSMC) strategies only drive the system representative point to a certain vicinity of that hyperplane. In established literature on DSMC, the width of this vicinity has always been strictly greater than zero in the presence of uncertainties. Thus, ideal sliding motion was considered impossible for discrete-time systems. In this paper, a new approach to DSMC design is presented with the aim of driving the system representative point exactly onto the sliding hyperplane even in the presence of uncertainties. As a result, the quasi-sliding mode band width is effectively reduced to zero and ideal discrete-time sliding motion is ensured. This is achieved with the proper selection of the sliding hyperplane, using the unique properties of relative degree two sliding variables. It is further demonstrated that, even in cases where selection of a relative degree two sliding variable is impossible, one can use the proposed technique to significantly reduce the quasi-sliding mode band width.

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Comprehensive Analysis for Influence of Controllable Damper Time Delay on Semi-Active Suspension Control Strategies

Journal of Vibration and Acoustics ◽

10.1115/1.4035700 ◽

2017 ◽

Vol 139 (3) ◽

Cited By ~ 49

Author(s):

Yechen Qin ◽

Feng Zhao ◽

Zhenfeng Wang ◽

Liang Gu ◽

Mingming Dong

Keyword(s):

Time Delay ◽

Dynamic Characteristics ◽

Ride Comfort ◽

Hybrid Control ◽

Sliding Mode ◽

Control Strategies ◽

Active Suspension ◽

Test System ◽

Suspension Control ◽

Simulation Results

This paper presents a comprehensive comparison and analysis for the effect of time delay on the five most representative semi-active suspension control strategies, and refers to four unsolved problems related to semi-active suspension performance and delay mechanism that existed. Dynamic characteristics of a commercially available continuous damping control (CDC) damper were first studied, and a material test system (MTS) load frame was used to depict the velocity-force map for a CDC damper. Both inverse and boundary models were developed to determine dynamic characteristics of the damper. In addition, in order for an improper damper delay of the form t+τ to be corrected, a delay mechanism of controllable damper was discussed in detail. Numerical simulation for five control strategies, i.e., modified skyhook control SC, hybrid control (HC), COC, model reference sliding mode control (MRSMC), and integrated error neuro control (IENC), with three different time delays: 5 ms, 10 ms, and 15 ms was performed. Simulation results displayed that by changing control weights/variables, performance of all five control strategies varied from being ride comfort oriented to being road handling oriented. Furthermore, increase in delay time resulted in deterioration of both ride comfort and road handling. Specifically, ride comfort was affected more than road handling. The answers to all four questions were finally provided according to simulation results.

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An Adaptive Droop Control Scheme Based on Sliding Mode Control for Parallel Buck Converters in Low-Voltage DC Microgrids

10.1109/cieec50170.2021.9510595 ◽

2021 ◽

Author(s):

Yu Li ◽

Fei Tang ◽

Xiaoqing Wei ◽

Fanghua Qin ◽

Tongyan Zhang

Keyword(s):

Sliding Mode Control ◽

Low Voltage ◽

Sliding Mode ◽

Buck Converters ◽

Droop Control ◽

Dc Microgrids ◽

Mode Control ◽

Control Scheme

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Control of inverters in standalone andgrid-connected microgrid using different control strategies

World Journal of Engineering ◽

10.1108/wje-09-2020-0432 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Vikash Gurugubelli ◽

Arnab Ghosh

Keyword(s):

Transient Response ◽

Control Strategy ◽

Control Strategies ◽

Power Balance ◽

Droop Control ◽

Content Type ◽

Simulink Simulation ◽

Time Simulation ◽

Simulation Results ◽

First Time

Purpose The share of renewable energy sources (RESs) in the power system is increasing day by day. The RESs are intermittent, therefore maintaining the grid stability and power balance is very difficult. The purpose of this paper is to control the inverters in microgrid using different control strategies to maintain the system stability and power balance. Design/methodology/approach In this paper, different control strategies are implemented to the voltage source converter (VSC) to get the desired performance. The DQ control is a basic control strategy that is inherently present in the droop and virtual synchronous machine (VSM) control strategies. The droop and VSM control strategies are inspired by the conventional synchronous machine (SM). The main objective of this work is to design and implement the three aforementioned control strategies in microgrid. Findings The significant contributions of this work are: the detailed implementation of DQ control, droop control and VSM control strategies for VSC in both grid-connected mode and standalone mode is presented; the MATLAB/Simulink simulation results and comparative studies of the three aforementioned controllers are introduced first time in the proposed work; and the opal-RT digital real-time simulation results of the proposed VSM control show the superiority in transient response compared to the droop control strategy. Research limitations/implications In the power system, the power electronic-based power allowed by VSM is dominated by the conventional power which is generated from the traditional SM, and then the issues related to stability still need advance study. There are some differences between the SM and VSM characteristics, so the integration of VSM with the existing system still needs further study. Economical operation of VSM with hybrid storage is also one of the future scopes of this work. Originality/value The significant contributions of this work are: the detailed implementation of DQ control, droop control and VSM control strategies for VSC in both grid-connected mode and standalone mode is presented; the MATLAB/Simulink simulation results and comparative studies of the three aforementioned controllers are introduced first time in the proposed work; and the opal-RT digital real-time simulation results of the proposed VSM control show the superiority in transient response compared to the droop control strategy.

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Development of a Laboratory Equipment for Dynamic Systems and Process Control Education

Volume 5: Education and Globalization ◽

10.1115/imece2014-38924 ◽

2014 ◽

Cited By ~ 2

Author(s):

Rafael E. Vásquez ◽

Norha L. Posada ◽

Fabio Castrillón ◽

David Giraldo

Keyword(s):

Process Control ◽

Dynamic Systems ◽

Sliding Mode ◽

Control Strategies ◽

Academic Research ◽

Nonlinear Behavior ◽

Industrial Training ◽

Laboratory Equipment ◽

Dynamic Matrix ◽

Control Education

This paper addresses the development of an equipment to teach control engineering fundamentals. The design requirements were determined by users that perform academic, research and industrial training tasks in the area of dynamic systems and process control. Such requirements include: industrial instrumentation; measurement of controlled and manipulated variables, and disturbances; process reconfigurability; different control technologies; several control strategies; appropriate materials for visualization; and compact shape to optimize lab space. The selected process is a tank system that allows one to choose among several dynamic behaviors: first, second, and third order, linear and nonlinear behavior, and dead time; the mathematical model that represents the dynamics of the system is presented. A traditional 3-stage design methodology that includes conceptual, basic and detailed design was followed. The developed equipment allows the user to select from three different technological alternatives to control the system: a PLC, an industrial controller, and a computer. With such flexibility, several control strategies can be implemented: feedback, feedforward, PID, LQG, nonlinear control (gain scheduling, sliding mode, etc.), fuzzy logic, neural networks, dynamic matrix control, etc. The developed system is being used to teach undergrad courses, grad courses, and industrial training. Additionally, the equipment is useful in research projects where grad students and researches can implement and test several advanced control techniques.

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