Bumpless Transfer Research Articles

Almost output regulation bumpless transfer control for switched linear systems

This study focuses on the problem of almost output regulation bumpless transfer control for switched linear systems. The authors aim at solving the almost output regulation problem with the bumpless transfer performance achieved via a multiple Lyapunov functions scheme. First, a concept of the bumpless transfer performance for a switched linear system is introduced. Then, a sufficient condition on the almost output regulation bumpless transfer performance of the system is obtained by dual design of a controller and a switching law. The sufficient condition allows that each subsystem does not satisfy the almost output regulation bumpless transfer property. Furthermore, a solution to the almost output regulation bumpless transfer control problem for the system is also offered in terms of linear matrix equalities and linear matrix inequalities. Finally, an example of controlling a turbofan model is given, showing that the proposed control strategy is effective.

L2 bumpless transfer control for switched linear systems with stability

ABSTRACTThis paper focuses on the issue of bumpless transfer control for a class of switched linear systems with stability. First, a concept of bumpless transfer performance for a system in this class is introduced. Second, sufficient conditions for the bumpless transfer performance, stabilisation and disturbance rejection are presented by co-design of a switching law and a compensator. The sufficient conditions allow each closed-loop subsystem not to satisfy the bumpless transfer performance, stabilisation and disturbance rejection. Furthermore, a solution to the bumpless transfer control problem for the system with stability is also provided in terms of linear matrix inequalities (LMIs). Finally, an example is given to show the effectiveness of the proposed method.

Rapid Control Prototyping With Scilab/Scicos, RTAI-Lab for the Mic955 Training Module of the Feedback Instruments

A rapid control prototyping system for the MIC955 module of the feedback instruments is described. The system is supported on a computer with open source tools GNU Linux Fedora, Scilab/Scicos, and RTAI-Lab. The following are the phases of a control system design: 1) specifications: 2) modeling and identification; 3) analysis controller; 4) simulation; 5) implementation, and 6) verification in a development environment. Communication interfaces enable the MIC955 module and a palette of RTAI-Lab components to do rapid control prototyping with the module. It helps to increase system's educational potential in the performance temperature control in the MIC955 module, implementing AntiWindup, and Bumpless transfer compensation.

[formula omitted] bumpless transfer control for switched linear systems with almost output regulation

In this paper, the issue of L2 bumpless transfer control for switched linear systems with almost output regulation property is investigated. First, a description of the L2 bumpless transfer performance for a category of switched linear systems is given to measure the output bumpless transfer levels of the systems. Then, a compensator and a switching law are designed via a multiple Lyapunov functions strategy. Under the designed compensator and switching law, a sufficient condition guaranteeing the L2 bumpless transfer property and the almost output regulation property of the systems is presented. Furthermore, the sufficient condition allows each subsystem not to have both properties. At last, an example showing the effectiveness of the proposed control scheme is offered by controlling a turbofan model.

Anti-Windup and Disturbance Rejection Controller Design of an Automated Oxygen Control System for Premature Infants.

For premature infants, the peripheral oxygen saturation (SpO2) level has significant effects on their health. Manual control of the fraction of inspired oxygen (FiO2) by nursing staff is not only a highly labor intensive solution, but also a hard task to maintain infants' SpO2 within the safe range. For this clinical need, an automated oxygen control system for premature infants is developed, which is based on PI control and derivative feedback (DF) control. Clinical tests showed that, when there is either a manual-automatic mode switch and tube feeding, integral windup may occur which will lead to the degradation of control performance. To overcome this problem, an anti-windup control strategy is developed. Due to blood oxygen desaturations caused by unknown disturbances, a disturbance observer is adopted with the disturbance estimate used for disturbance rejection. According to the results of dynamic simulations, the controller with anti-windup and disturbance rejection design has the best performance among all controllers, it could achieve bumpless transfer during mode switching, decrease FiO2 in a timely manner when feeding is finished, and can shorten the recovery time from desaturation events and after feeding. This controller could minimize the time that SpO2 is outside the safe range, which is promising for clinical application.

Parameterized Disturbance Observer Based Controller to Reduce Cyclic Loads of Wind Turbine

This paper is concerned with bump-less transfer of parameterized disturbance observer based controller with individual pitch control strategy to reduce cyclic loads of wind turbine in full load operation. Cyclic loads are generated due to wind shear and tower shadow effects. Multivariable disturbance observer based linear controllers are designed with objective to reduce output power fluctuation, tower oscillation and drive-train torsion using optimal control theory. Linear parameterized controllers are designed by using a smooth scheduling mechanism between the controllers. The proposed parameterized controller with individual pitch was tested on nonlinear Fatigue, Aerodynamics, Structures, and Turbulence (FAST) code model of National Renewable Energy Laboratory (NREL)’s 5 MW wind turbine. The closed-loop system performance was assessed by comparing the simulation results of proposed controller with a fixed gain and parameterized controller with collective pitch for full load operation of wind turbine. Simulations are performed with step wind to see the behavior of the system with wind shear and tower shadow effects. Then, turbulent wind is applied to see the smooth transition of the controllers. It can be concluded from the results that the proposed parameterized control shows smooth transition from one controller to another controller. Moreover, 3p and 6p harmonics are well mitigated as compared to fixed gain DOBC and parameterized DOBC with collective pitch.

H∞ bumpless transfer for switched LPV systems and its application

ABSTRACTIn this paper, the approach of the control bumps limitation is generalised and applied to the problem of H∞ bumpless transfer for a class of switched linear parameter-varying (LPV) systems. The H∞ bumpless transfer problem is to design a controller with the amplitude limitation and a parameter and modes-dependent switching law to reduce control bumps of the switched LPV systems and satisfy an H∞ performance index. The key point is to guarantee the bumps limitation constraint of the switched LPV systems by dual design of controllers and a switching law, even though the constraint for each subsystem is unsatisfied. First, a set of switching signals depending on parameters and modes are designed, and a family of switched LPV controllers with the bumps limitation objective are developed via multiple parameter-dependent Lyapunov functions. Then, a sufficient condition ensuring the H∞ bumpless transfer performance for a switched LPV system is presented in the format of numerically tractable conditions. Finally, the effectiveness of the proposed control design scheme is illustrated by its application to the control design of an aero-engine.

H∞ Reliable Bumpless Transfer Control for Switched Systems With State and Rate Constraints

This paper concentrates on the issue of ${H} _{\infty}$ reliable bumpless transfer control for a category of switched systems (SSs) with state and rate constraints. The ${H} _{\infty}$ reliable bumpless transfer control problem refers to designing a collection of reliable controllers and a switching rule to ensure the SSs to satisfy the bumpless transfer performance and ${H} _{\infty}$ reliable property. First, a concept of the bumpless transfer performance for a system in this category with possible actuator faults is introduced. Then, by a multiple Lyapunov functions approach, a switching rule and a set of reliable controllers are co-designed to assess the disturbance tolerance capability with bumpless transfer performance and to solve the ${H} _{\infty}$ reliable bumpless transfer control problem of the system. Second, a criterion guaranteeing the bumpless transfer performance and ${H} _{\infty}$ reliable property of the system is established. The criterion allows each subsystem not to possess both the bumpless transfer performance and ${H} _{\infty}$ reliable property. Further, an algorithm is proposed to estimate the attraction domain of the system without disturbances. Finally, the effectiveness of the presented control scheme is verified by an example of controlling a turbofan model.

Linear Quadratic Regulator-Based Bumpless Transfer in Microgrids

This paper presents a linear quadratic regulator (LQR)-based bumpless transfer controller for achieving seamless transition between the grid connected and the islanded modes of operation in microgrids. During the grid connected mode, the inverter-based distributed generators (DGs) operate in current controlled mode where they supply a constant active and reactive power. During the islanded mode, the inverters operate in voltage controlled mode. During transition between the two control modes severe transients can occur in the system which affect the voltage and frequency responses. The proposed bumpless compensator reduces the error between the outputs of two controllers at the instant of transition by optimally reducing an error measure based on LQR theory. The efficacy of the proposed controller is tested on a microgrid test system. Several operating scenarios on the microgrid have been tested using the proposed approach. It has been found that the proposed controller is effective in reducing the voltage and the frequency transients during transition.

Mode switching control for a multi-functional variable refrigerant flow system

The multi-functional variable refrigerant flow system enables simultaneous heating and cooling of the zones it serves by allowing the heat exchangers of both indoor units and outdoor units to operate as evaporators or condensers. To realize automatic and smooth switching between different modes, a mode switching strategy is proposed for a multi-functional variable refrigerant flow system. Whether to turn on or off an indoor unit is determined by the zone temperature and a preset hysteresis band about the temperature set-point. Based on a thermodynamic analysis, a decision variable for determining outdoor unit-heat exchangers mode switching is proposed as the outdoor unit-heat exchangers airside temperature differential normalized by the dimensionless outdoor unit fan speed. Two bumpless transfer strategies are applied to produce smooth mode switching. To evaluate the proposed strategy, a simulation study is performed with a Modelica-based dynamic simulation model of a four-zone multi-functional variable refrigerant flow system. Simulation results validate the effectiveness of the proposed strategy and the performance of the bumpless transfer strategies.

Review of different fault detection methods and their impact on pre‐emptive VSC‐HVDC dc protection performance

Multi-terminal voltage-sourced converters (VSC) high-voltage direct current (HVDC) transmission system is expected to play a vital role in future power systems. Compared with ac power transmission, dc transmission is more vulnerable to faults due to low dc-side impedances and sensitive power electronics in the converters. Dc protection issues must be tackled before any multi-terminal VSC-HVDC grid can be built. The multi-terminal VSC-HVDC system is studied in detail using switching models for two-level converters, detailed equivalent models for the modular multi-level converters, detailed hybrid circuit breaker switching models and frequency-dependent phase models for dc cables. Using such high-fidelity system models, a systematic study of HVDC fault protection methodologies in more detail than previous studies is conducted. This is the first comprehensive study that includes pre-emptive circuit breaker operation. The results presented in this study underline the benefits of such a detailed treatment of the breaker, and of considering it as part of a fast power electronics system rather than isolated dc equipment. The study identifies the best existing fault detection method and tests it extensively. In order to further improve post-fault system recovery response, which is a key but often neglected part of previous studies, a novel bump-less transfer control has been implemented in the converters.

A Detailed Modular Governor-Turbine Model for Multiple-Spool Gas Turbine With Scrutiny of Bleeding Effect

Multiple-spool gas turbines are usually utilized for power supply in aircrafts, ships, and terrestrial electric utility plants. As a result, having a reliable model of them can aid with the control design process and stability analysis. Since several interconnected components are coupled both thermodynamically and through shafts, these engines cannot be modeled linearly as single shaft gas turbines. In this paper, intercomponent volume method (ICV) has been implemented for turbine modeling. A switched feedback control system incorporating bump-less transfer and antiwindup functionality is employed as governor for the engine. Validation with test results from a three spool gas turbine highlights high accuracy of turbine-governor model in various maneuvers. Results show that over-speed after load rejection is considerable due to the fact that in this arrangement, the power turbine (PT) is not coupled with the compressor which acts like a damper for single shaft gas turbines. To address this problem, bleed valves (mainly before combustion chamber) are used to arrest the over-speed by 20%. In addition, a switch is employed into the governor system to rapidly shift fuel to permissible minimum flow.

Observer-based bumpless switching control for switched linear systems with sensor faults

This paper investigates the bumpless transfer problem of switched linear systems with sensor faults. The framework of the switched control systems includes two kinds of controllers, one is for normal use and the other is for fault-tolerant control when sensor faults have occurred. Considering that the information of the sensor faults is unknown to the controller, an observer is designed for the fault-tolerant controller. Moreover, in view of the issue that the output difference between the online and offline controllers may induce undesired oscillations in control input at the switching instant, a bumpless transfer compensator is presented based on sliding mode control. Due to the reasonably designed compensator, the difference can be minimized to a small value to guarantee smooth transitions of the control input when sensor faults have occurred. Finally, numerical simulations verify the effectiveness of the proposed method.

Variable Structure H∞ Controller for Aircraft

This paper proposes a new synthesis method and tuning procedure for a variable structure H∞ multivariable controller for fixed wing aircrafts attitude control, which consists in switching from one-degree of freedom controller (1-DOF) to two degrees of freedom controller (2-DOF), and vice versa, with a method for bump-less transfer in switching transitions. The proposed method is tested using robustness analysis based on frequency domain and time analysis computer simulations based on a nonlinear mathematical model of the F-16 aircraft published by the NASA, from which satisfactory results are obtained.

On Tuning and Practical Implementation of Active Disturbance Rejection Controller: A Case Study from a Regenerative Heater in a 1000 MW Power Plant

Active disturbance rejection controller (ADRC) is emerging as a promising approach to deal with uncertainties, which has received many practical applications in motion controls. This paper discusses the issues that should be taken into account when applying ADRC in process industry. First, the strategies of bumpless transfer and anti-windup are introduced to make ADRC applicable for continuous production processes. Second, an automatic tuning tool, based on robust loop shaping, is developed to obtain a group of reasonable parameters that can guarantee the system safety when ADRC is put in loop. For robustness concerns, the maximum sensitivity function is introduced in tuning the bandwidth of the extended state observer (ESO). Third, a quantitative retuning strategy is introduced to avoid the proportional kick in set-point tracking. The simulation and laboratory experiments confirm the effectiveness of the proposed strategies. Finally, it is attempted to apply the ADRC controller to a regenerative heater i...

Fuzzy-Neural Petri Net Distributed Control System Using Hybrid Wireless Sensor Network and CAN Fieldbus

The reluctance of industry to allow wireless paths to be incorporated in process control loops has limited the potential applications and benefits of wireless systems. The challenge is to maintain the performance of a control loop, which is degraded by slow data rates and delays in a wireless path. To overcome these challenges, this paper presents an application–level design for a wireless sensor/actuator network (WSAN) based on the “automated architecture”. The resulting WSAN system is used in the developing of a wireless distributed control system (WDCS). The implementation of our wireless system involves the building of a wireless sensor network (WSN) for data acquisition and controller area network (CAN) protocol fieldbus system for plant actuation. The sensor/actuator system is controlled by an intelligent digital control algorithm that involves a controller developed with velocity PID-like Fuzzy Neural Petri Net (FNPN) system. This control system satisfies two important real-time requirements: bumpless transfer and anti-windup, which are needed when manual/auto operating aspect is adopted in the system. The intelligent controller is learned by a learning algorithm based on back-propagation. The concept of petri net is used in the development of FNN to get a correlation between the error at the input of the controller and the number of rules of the fuzzy-neural controller leading to a reduction in the number of active rules. The resultant controller is called robust fuzzy neural petri net (RFNPN) controller which is created as a software model developed with MATLAB. The developed concepts were evaluated through simulations as well validated by real-time experiments that used a plant system with a water bath to satisfy a temperature control. The effect of disturbance is also studied to prove the system's robustness.

Practical Active Disturbance Rejection Control: Bumpless Transfer, Rate Limitation, and Incremental Algorithm

Practical applications of controllers often impose further requirements on the implementation beyond the actual control performance, such as the ability to switch between manual and automatic control or between different control laws or controller parameter settings, known as bumpless transfer. Another common requirement is to limit the control signal in magnitude and/or rate. This article examines and extends several discrete-time variants of active disturbance rejection control (ADRC), which is increasingly being applied especially in the field of power electronics and drives, in this regard. Detailed guidelines for practical ADRC implementations with these abilities are presented, and all features are being demonstrated with the help of simulation examples.

Bumpless Transfer-Based Inter-Region Controller Switching of Wind Turbines for Reducing Power and Load Fluctuation

For wind turbine operation, wind variations around the rated wind speed can lead to frequent controller switching actions, which may result in significant fluctuation in power output and structural load. This paper presents a bumpless transfer scheme for the inter-region controller switching for variable-speed variable-pitch wind turbines, which aims to reduce the associated power fluctuation and fatigue load. The study follows a typical partition of Region 2 (maximum power capture control), Region 2.5 (rotor speed regulation), and Region 3 (constant power control) around the rated wind speed. Two relatively simple bumpless transfer techniques, i.e., 1)the conditioning technique and 2)the linear quadratic (LQ) technique, respectively, are employed for different situations of inter-region controller switching. The conditioning bumpless transfer approach is adopted for switching between Regions 2 and 2.5 via generator torque control. The LQ bumpless transfer technical is applied to the switching between Regions 2.5 and 3, when the generator torque is saturated at its rated value, the pitch controller takes over so as to limit the load of wind turbine. The simulation results demonstrated the effectiveness of the proposed scheme of inter-region switching, with significant reduction of power flicker and structural load.

Nonlinear Unfalsified Adaptive Control with Bumpless Transfer and Reset

Abstract: The BHMT (Battistelli-Hespanha-Mosca-Tesi) reset mechanism which is a new scheme to control time-varying plant under the framework of unfalsified adaptive control is investigated. The reset condition is modified based on the gains of the control system components, making it adaptive, free of uncertain parameters, and practically implementable in a switching algorithm. The framework of generalized bumpless transfer system is established for switching of a controller. Performance including stability is proved given that the adaptive stabilization problem is feasible. The proposed switching algorithm is nonlinear time-varying and it can control nonlinear time-varying plant using nonlinear controllers.

Bumpless Transfer for Convenient Lateral Car Control Handover

Besides longitudinal control, advanced driver assistance functions additionally require lateral control. Up to now, many different control approaches have been proposed and documented in literature dealing with lateral control. In contrast to this, there are only very few publications describing the handling of comfortable handover from manual to assisted driving controlling lateral car dynamics.The presented work aims to enhance handover at the activation of lateral control by significantly reducing lateral acceleration and jerk, resulting in smooth and comfortable control handover.First a state of the art model-based control is outlined. Based on this application, a flatness-based approach for bumpless transfer from manual to controlled mode is proposed. Both, model-based control and bumpless transfer extension, allow straightforward tuning and execution on standard automotive hardware, due to their low computational effort. Results are discussed on simulation results.