Lead-lag Controller Research Articles

Coordinated Design of PSS and TCSC Controller for Power System Damping Improvement with Multiple Control Design Requirements

In this paper an Optimization based linear control design method is used to achieve a coordinated design of Power System Stabilizer (PSS) and Thyristor Controlled Series Capacitor (TCSC) for power system damping improvement with pre specified control design requirements. The settling time is considered as main performance criteria in time domain specification and gain and phase margins for frequency domain specifications. The main objective of the coordination of controllers is to improve the global stability through damping of oscillations by improving the damping ratio of the system and minimizing the settling time of the system response. Thus coordination increases the reliability of the system and maintains the required damping even one or more controllers are out of service and hence reduces the need for additional controller. Optimization based linear control design is used to determine the optimal gain and time constant setting of lead-lag controller parameters for PSS and TCSC. The coordinated PSS and TCSC controller is tested in the Single Machine Infinite Bus Power System (SMIB). Simulation is carried out using Matlab2011b. From the time domain simulation results it is observed that oscillations are damped out, settling time is reduced and damping ratio is improved. From bode plot it is inferred that gain and phase margin of the system is further improved to satisfy the system requirements. In the overall analysis, optimization based linear control design implemented for the coordination of PSS and TCSC controller satisfies the practical requirements of the power system oscillation damping problem, also shift the eigen values to the left half of the s-plane as far as possible and hence enhances the overall system stability

A mock circulation model for cardiovascular device evaluation

The aim of this study was to develop an integrated mock circulation system that functions in a physiological manner for testing cardiovascular devices under well-controlled circumstances. In contrast to previously reported mock loops, the model includes a systemic, pulmonary, and coronary circulation, an elaborate heart contraction model, and a realistic heart rate control model. The behavior of the presented system was tested in response to changes in left ventricular contractile states, loading conditions, and heart rate. For validation purposes, generated hemodynamic parameters and responses were compared to literature. The model was implemented in a servo-motor driven mock loop, together with a relatively simple lead-lag controller. The pressure and flow signals measured closely mimicked human pressure under both physiological and pathological conditions. In addition, the system's response to changes in preload, afterload, and heart rate indicate a proper implementation of the incorporated feedback mechanisms (frequency and cardiac function control). Therefore, the presented mock circulation allows for generic in vitro testing of cardiovascular devices under well-controlled circumstances.

Optimal Controller for Wind Energy Conversion Systems

Increasing of word demand load is caused a new Distributed Generation (DG) enter to power system. One of the most renewable energy is the Wind Energy Conversion System (WECS), which is connected to power system using power electronics interface or directly condition. In this paper an optimal Lead-Lag controller for wind energy conversion systems (WECS) has been developed. The optimization technique is applied to Lead-Lag optimal controller in order to control of the most important types of wind system with doubly Fed Induction Generator is presents. Nonlinear characteristics of wind variations as plant input, wind turbine structure and generator operational behavior demand for high quality optimal controller to ensure both stability and safe performance. Thus, Honey Bee Mating Optimization (HBMO) is used for optimal tuning of Lead-Lag coefficients in order to enhance closed loop system performance. In order to use this algorithm, at first, problem is written as an optimization problem which includes the objective function and constraints, and then to achieve the most desirable controller, HBMO algorithm is applied to solve the problem. In this study, the proposed controller first is applied to two pure mathematical plants, and then the closed loop WECS behavior is discussed in the presence of a major disturbance. Simulation results are done for various loads in time domain, and the results show the efficiency of the proposed controller in contrast to the previous controllers.

The Booting-Type ADRC of Airborne Photoelectrical Platform

Customary disturbance rejection in the photoelectrical platform is “passive,” which makes it difficult to further improve the isolation degree owning to the strict restriction of mechanical resonance frequency. In this paper, a booting-type ADRC is proposed, whose disturbance estimation process is guided by target value to reduce the overshoot and lag in the estimated value of disturbance. All kinds of disturbance in the system are modeled in a unified way by using the equivalent disturbance voltage to avoid the complex modeling process. Based on the simplified model, extended state observer (ESO) is designed to realize a real-time estimation of the disturbance. Then, the disturbance compensation is added to generate the final control value by combining the customary square lead-lag controller. Experiments are implemented to test the proposed control strategy by mounting the photoelectrical platform on a flight simulator and generating a motion perturbation. Compared with the case of only traditional lead-lag controller, the isolation degree of disturbance is enhanced obviously. And the experiments also illustrate strong robustness of ADRC.

English

This paper proposes a Lead-Lag optimal controller in order to control of one of the most important types of fuel cell, namely proton exchange membrane fuel cell (PEMFC). At first, the introducing and implementation of the PEMFC is present and next, during system load variations the proposed controller is designed. The controller should be designed against the load variations for keeping in a fixed value of fuel cell output voltage. Here, the Lead-Lag Controller is used which its coefficients are optimized based on Honey Bee Mating Optimization (HBMO). In order to use this algorithm, at first, the problem is written as an optimization problem which includes the objective function and constraints, and then to achieve the most desirable controller, HBMO algorithm is applied to solve the problem. Simulation results are done for various loads in time domain, and the results show the efficiency of the proposed controller in contrast to the previous controllers. Key words: Lead-Lag controller, proton exchange membrane fuel cell (PEMFC), Honey Bee Mating Optimization (HBMO), fuel cell output voltage.

Optimal lead-lag controller designing for reduction of load current total harmonic disturtion and hanmonic with voltage control using honey bee mating optimization (HBMO)

Increase in world demand load has resulted in new distributed generation (DG) that has entered into the power system. One of the most renewable energies is fuel cell, which is connected to power system using a power electronics interface in microgrid or standalone condition. The highest problem of this switching interface based DGs is the power quality (PQ) and harmonics of currents. Also, the voltage of the DGs should be controlled in islanding condition. In this paper, we present a Lead-Lag optimal controller for controlling one of the most important types of fuel cell, namely proton exchange membrane fuel cell (PEMFC) in islanding mode operation for reducing PQ problems and voltage control. At first, the introduction and implementation of the PEMFC is present and next, during system load variations the proposed controller is designed. The controller should be designed against the demand load variations of fuel cell. Here, the lead-lag controller is used when its coefficients are optimized based on honey bee mating optimization (HBMO). In order to use this algorithm, at first, the problem is written as an optimization problem which includes the objective function and constraints, and then to achieve the most desirable controller, HBMO algorithm is applied to solve the problem. Simulation results are done for various loads in time domain, and the results show the efficiency of the proposed controller in contrast to the previous controllers. Key words: Power system, fuel cell.

Damping of low‐frequency oscillations using an SVC‐based supplementary controller

AbstractIn this paper, the optimal tunning problem of parameters of a conventional lead–lag controller (LLC) and a fuzzy logic controller (FLC) based on the static Var compensator (SVC) is considered. The solution is obtained using an improved particle swarm optimization (IPSO) algorithm. The membership functions and scaling factors of the FLC and LLC parameters are optimized using the above‐mentioned technique. The proposed controllers are settled down to an SVC that is installed at the middle of a transmission line connecting a single machine to an infinite bus system. Simulation results show the superiority of the optimized FLC compared to the optimized LLC and also when the SVC is without the supplementary controller under different disturbances and loading conditions. The simulations and analyses are implemented in MATLAB environment. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

유전자 알고리즘과 콤플렉스법에 의한 직접구동형 서보밸브의 제어기 상수값 설계

The control system of a direct drive servo valve is a nonlinear system, and the flow force effect on the spool motion is significant and dependent on the load pressure. To satisfy the control system design requirements, the optimal parameters of the lead-lag controller and the derivative feedback controller are searched for using a genetic algorithm and a complex constrained direct search type method. The obtained controller parameters successfully perform their role to satisfy the control system design requirements.

Coordinated Control of Flexible AC Transmission System Devices Using an Evolutionary Fuzzy Lead-Lag Controller With Advanced Continuous Ant Colony Optimization

This paper proposes an evolutionary fuzzy lead-lag control approach for coordinated control of flexible AC transmission system (FACTS) devices in a multi-machine power system. The FACTS devices used are a thyristor-controlled series capacitor (TCSC) and a static var compensator (SVC), both of which are equipped with a fuzzy lead-lag controller to improve power system dynamic stability. The fuzzy lead-lag controller uses a fuzzy controller (FC) to adaptively determine the parameters of two lead-lag controllers at each control step according to the deviations of generator rotor speeds. This paper proposes an Advanced Continuous Ant Colony Optimization (ACACO) algorithm to optimize all of the free parameters in the FC, which avoids the time-consuming task of parameter selection by human experts. The effectiveness and efficiency of the proposed evolutionary fuzzy lead-lag controller for oscillation damping control is verified through control of a multi-machine power system and comparisons with other lead-lag controllers and various population-based optimization algorithms.

Nonlinear Lead-Lag Controller Synthesis for Unstable Nonlinear Systems

AbstractA new systematic procedure for synthesis of nonlinear lead-lag controllers for highly nonlinear unstable plants is developed. The procedure is to stabilize the unstable plant followed by generation of sinusoidal-input describing function (SIDF) models at various operating regimes of interest. The unstable plant frequency domain behavior is extracted, and a set of linear lead-lag controllers are designed that would force the open-loop behavior of the system (comprised of the lead-lag controller and the nonlinear plant) and mimic that of desired. Finally, a describing function inversion is used, and the nonlinear functions describing the values of the lead-lag coefficients as a function of the error signal are obtained. Experimental results are presented for verification, and bounded-input bounded-output stability is demonstrated by successful generation of the describing function models of the closed-loop system comprised of the synthesized nonlinear lead-lag controller and the nonlinear plant.

Design and Implementation of a Radial Magnetic Bearing With Permanent Magnet Bias

A new yoke winding for a radial magnetic bearing with permanent magnet bias flux is investigated and shown to reduce the copper loss and copper cost, by 32% in the prototype built. Magnetic circuit analysis neglecting fringing was found to give a poor estimate of the permanent magnet bias flux and 3D finite element analysis (FEA) would be needed to model it. However, 2D FEA was sufficient to model the magnetic field and force in the plane of the stator laminations, providing that the correct bias flux was imposed as a boundary condition. Solutions for the axial magnetic vector potential component Az were obtained, with a discontinuity prescribed across a cut from the inner to outer domain boundary. A small prototype was built and tested on a shaft whose other end was supported by a ball bearing race with free angular movement. For each of the horizontal and vertical directions, closed loop control was applied with Hall elements providing the shaft position signal. A lead-lag controller, designed using Matlab Simulink and implemented in Turbo Pascal 6, levitated the rotor.

On the Centralized Nonlinear Control of HVDC Systems Using Lyapunov Theory

The security region of a power system is an important and timely issue; different stability criteria may be limiting. Rotor-angle stability can be improved by modulating active power of installed high-voltage direct current (HVDC) links. This paper proposes a new centralized nonlinear control strategy for coordinating several point-to-point and multiterminal HVDC systems based on Lyapunov theory. The proposed control Lyapunov function is negative semi-definite along the trajectories and uses the internal node representation of the system. The proposed control Lyapunov function increases the domain of attraction and, thus, improves the rotor-angle stability. Nonlinear simulations are performed on the IEEE 10-machine 39-bus system which shows the effectiveness of the controller. In comparison, simulations using the conventional lead-lag controller are also run.

Posicast control of a class of fractional-order processes

AbstractThe number of studies on the control of fractional-order processes—processes having dynamics described by differential equations of arbitrary order—has been increasing in the past two decades and it is now ubiquitous. Various methods have emerged and have been proven to effectively control such processes—usually resulting in fractional-order controllers similar to their conventional integer-order counterparts, which include, but are not limited to fractional PID and fractional lead-lag controllers. However, such methods require a lot of computational effort and fractional-order controllers could be challenging when it comes to their synthesis and implementation. In this paper, we propose a simple yet effective delay-based controller with the use of the Posicast control methodology in controlling the overshoot of a fractional-order process of the class $$\mathcal{P}:\left\{ {P\left( s \right) = {1 \mathord{\left/ {\vphantom {1 {\left( {as^\alpha + b} \right)}}} \right. \kern-\nulldelimiterspace} {\left( {as^\alpha + b} \right)}}} \right\}$$ having orders 1 < α < 2. Such controllers have proven to be easy to implement because they only require delays and summers. In this paper, the Posicast control methodology introduced in the past few years is modified to minimize the overshoot of the processes step response to a level that is acceptable in control engineering and automation practices. Furthermore, proof of the existence of overshoot for such class of processes, as well as the determination of the peak-time of the open-loop response of a fractional-order process of the class P is presented. Validation through numerical simulations for a class of fractional-order processes are presented in this paper.

Genetically tuning of lead-lag controller in order to control of fuel cell voltage

The aim of this article is to introduce, implement and control the voltage of one of the most important types of fuel cell, namely proton exchange membrane fuel cell (PEMFC) during system load variations. Fuel cell output voltage should be kept in a constant value against the load variations, and a controller should be designed for this purpose. Here, the Lead-Lag Controller is used in which its coefficients are optimized based on genetic algorithm. In order to use this algorithm, at first, problem is written as an optimization problem which includes the objective function and constraints, and then to achieve the most desirable controller, Genetic Algorithm (GA) method is applied to solve the problem. Simulation results are done for various loads in time domain, and the results show the efficiency of the proposed controller in contrast to the previous controllers. Simulations show improved accuracy of the proposed controller performance to achieve this goal. Key words: Proton exchange membrane fuel cell (PEMFC), genetic algorithm, lead lag controller-optimization problem

Mechatronic Aeropendulum: Demonstration of Linear and Nonlinear Feedback Control Principles With MATLAB/Simulink Real-Time Windows Target

This paper presents a low-cost hands-on experiment for a classical undergraduate controls course for non-electrical engineering majors. The setup consists of a small dc electrical motor attached to one of the ends of a light rod. The motor drives a 2-in propeller and allows the rod to swing. Angular position is measured by a potentiometer attached to the pivot point. A custom-designed circuit board produces the controlled voltage input to the motor. The target board is powered and communicates with the PC through its USB port using a virtual RS-232 port. A simple MATLAB/Simulink module has been created to read the pendulum angle and send a command signal to the motor. The module is based on Real-time Windows Target software, which allows a sampling rate of up to 200 Hz. Students are able to design and test classical PID and phase lead-lag controllers, as well as modern controllers, including state-space controller design combined with feedback linearization. A semester-long series of assignments is described that can be carried out without the need for a specialized laboratory or teaching assistants. The project was tested in a classical control systems design class of senior-level mechanical engineering students. Student feedback and survey data on the effectiveness of the modules are also presented.

Artificial Neural Networks based UPFC for Damping Low Frequency Oscillations

Low Frequency Oscillations(LFO) are a frequent adverse phenomenon which increase the risk of instability for the power system and thus reduce the total and availability transfer capability.LFO occur in power systems because of lack of the damping torque in order to dominance to power system disturbances as change in mechanical input power. In the recent past Power System Stabilizer (PSS) was used to damp LFO. FACTs devices, such as Unified Power Flow Controller (UPFC), can control power flow and increase transient stability. So UPFC may be used to damp LFO instead of PSS. In this research the linearized model of synchronous machine (Heffron-Philips) connected to infinite bus (Single Machine-Infinite Bus: SMIB) with UPFC is used and also in order to damp LFO, adaptive ANN damping controller for UPFC is designed and simulated. Simulation is performed for various types of loads and for different disturbances. Simulation results demonstrate that the developed ANN damping controller would be more effective in damping electromechanical oscillations in comparison with the conventional lead-lag controller.

Decoupling and levitation control of a six-degree-of-freedom magnetically levitated stage with moving coils based on commutation of coil array

The research in the present paper focuses on decoupling the six-degrees-of-freedom motions of a magnetically levitated stage with moving coils and controlling the levitation motion. The decoupling is based on commutation of coil array, which is obtained reversely from the electromagnetic force/torque model of the stage. The control of levitation motion is carried out by a phase lead-lag controller designed on the criterion of minimum integral of time-weighted absolute error after gravity compensation modeling of the plant dynamics. Comprehensive simulations of the control system in MATLAB/Simulink and real levitation experiments on a digital signal processor-centered test platform are made to verify the six-degrees-of-freedom decoupling effect and the closed-loop control performances of the levitation degree of freedom. The results indicate that the six-degrees-of-freedom motions of the stage can be decoupled through coil array commutation and the levitation motion can be controlled by the phase lead-lag controller based on the gravity compensation model and designed on the criterion of minimum integral of time-weighted absolute error.

Optimization and coordination of SVC-based supplementary controllers and PSSs to improve power system stability using a genetic algorithm

In this piaper, a lead-lag structure is proposed as a main damping controller for a static VAR compensator (SVC) to diminish power system oscillations. To confirm the transient performance of the proposed controller, it was compared to a proportional integral derivative (PID) damping controller. Power system stability improvement was thoroughly examined using these supplementary damping controllers as well as a power system stabilizer i(PSS). The generic algorithm (GA) is well liked in the academic environment due to its immediate perceptiveness, ease of performance, and ability to impressively solve highly nonlinear objectives. Thus, the GA optimization technique was applied to solve an optimization problem and to achieve optimal parameters of the SVC-based supplementary damping controllers and PSS. The coordinated design problem of these devices was formulated as an optimization problem to reduce power system oscillations. The transient performance of the damping controllers and PSS were evaluated under a severe disturbance for a single-machine infinite bus (SMIB) and multimachine power system. The nonlinear simulation results of the SMIB power system suggest that power system stability was increasingly improved using the coordinated design of the SVC-based lead-lag controller and PSS, rather than the coordinated design of the SVC-based PID controller and PSS. Furthermore, the interarea and local modes of the oscillations were superiorly damped using the proposed controller in the multimachine power system.

Parametric analysis of pressure control system for Lungmen nuclear power plant

Pressure control systems (PCSs) are applied on nuclear reactors to stabilize the system pressure and reactor steam flow during normal operation, and control the system pressure smoothly when the reactor steam generation exceeds the steam flow used by turbine. The purpose of this study was to investigate the dynamic response of PCS for Lungmen nuclear power plant. The thermal-hydraulic analysis code, RETRAN-3D, was applied for the construction of Lungmen reactor model and the associated control systems, and the dynamic response of pressure control system was evaluated by means of the perturbations induced by the step change of pressure regulator setpoint. The important parameters such as values of overshooting and decay ratios were calculated by 121 code runs with different lead-lag time constants, discovering the effect of lead-lag controller on dynamic response. This parametric study indicates that the performance of PCS may be enhanced by adjustment of lead-lag time constants. Furthermore, an optimization algorithm will be coupled with Lungmen RETRAN model for optimization analysis, searching optimal lead-lag constants.

ANFIS approach for SSSC controller design for the improvement of transient stability performance

In this paper, an Adaptive Neuro-Fuzzy Inference System (ANFIS) method based on the Artificial Neural Network (ANN) is applied to design a Static Synchronous Series Compensator (SSSC)-based controller for the improvement of transient stability. The proposed ANFIS controller combines the advantages of a fuzzy controller as well as the quick response and adaptability nature of an ANN. The ANFIS structures were trained using the generated database by the fuzzy controller of the SSSC. It is observed that the proposed SSSC controller improves greatly the voltage profile of the system under severe disturbances. The results prove that the proposed SSSC-based ANFIS controller is found to be robust to fault location and changes in operating conditions. Further, the simulation results obtained are compared with the conventional lead-lag controller under various disturbances, namely three-phase unbalanced faults and other unbalanced faults to show the effectiveness and robustness of the proposed approach for SSSC.