Proportional Plus Integral Research Articles

Control Strategy Based on $\text{H}\infty$ Repetitive Controller With Active Damping for Islanded Microgrid

To overcome the drawbacks of the proportional plus integral (PI) control based strategy, i.e., limitation for harmonic suppression and performance deterioration under load variation, a voltage control strategy based on the $\text{H}\infty $ repetitive controller with inverter-side current feedback damping is proposed for the inverter in islanded microgrid. The $\text{H}\infty $ repetitive controller provides good robustness against parameter perturbation and ensures the output voltage of low total harmonic distortion. Compared with other damping methods, a good resonance suppression and a better attenuation of the high-order harmonics can be achieved under the proposed strategy, which further improves the control performance of the voltage repetitive control system. A state space model including the damping coefficient is built to implement order reduction of the high-order controller, thereby simplifying the digital implementation while nearly without performance degradation. Moreover, the frequency response analysis shows that the order reduction can improve the adaptability of the controller to parameter variation. Finally, experiments and simulations verify the correctness of the analysis.

Improved Sliding Mode Control for Permanent Magnet Synchronous Motor Speed Regulation System

Due to advantages such as high speed, high accuracy, low maintenance and high reliability, permanent magnet synchronous motor (PMSM) servo systems have been employed in many fields. In some cases, for example, speed fluctuations caused by load mutation would restrict the control stability, thereby limiting the usefulness of PMSM in high-precision applications. The speed regulation problem of PMSM servo control systems is discussed in this paper. A sliding mode disturbance control is developed in the vector control system to improve tracking performance of the PMSM system in order to suppress the speed fluctuations. The integration of sliding mode control and the proportional plus integral (PI) control can improve the performance of the closed-loop system and attenuate disturbances to a great extent. The proposed method can effectively improve the robustness and response speed of the system. Simulation and experimental analyses are conducted to demonstrate the superior properties of the proposed control method.

Plug in hybrid vehicle-wind-diesel autonomous hybrid power system: frequency control using FA and CSA optimized controller

Large integration of renewable energy in hybrid power system in isolated mode of operation make frequency control a challenging task. This paper investigates the performance of Cuckoo Search Algorithm (CSA) and Firefly Algorithm (FA) based frequency control strategy of such a hybrid power system, which is a unique work. The generating units of the system are plug in hybrid vehicle (PHEV), wind turbine generators, a diesel engine generator (DEG) and battery energy storage system (BESS). The proportional plus integral (PI)/proportional integral derivative (PID) controllers are employed with PHEV, DEG and BESS to adjust the total active power generation in accordance to the load demand. Addition of PHEV reduces the reliance on the DEG or BESS as a result of variability and uncertainty of wind power. Different disturbance conditions such as step perturbations, random variations of load as well as wind output power, have been considered in the case studies under Matlab simulation to assess the performance of CSA and FA based control strategy. Analysis indicates that CSA based PID controller provides better response compare to GA, PSO and FA based PI/PID controller and CSA based PI controller. Sensitivity analysis has been carried out to check the robustness of FA and CSA optimized PI/PID controller gains.

Control of Third Order Processes Using Optimized Synthesis PI Controller

In closed loop system with PI controller, the most and severe problem is peak overshoot minimization in the closed loop response and tuning the proportional plus integral (PI) controller parameters. This paper deals with the two different tuning methods for obtain the PI controller settings. These methods are used to tune the parameters of PI controller and the closed loop performances of two methods are analyzed for the control of third order processes. From the closed loop responses, the time responses are move to unstable characteristics and the process variables are oscillates due to PI parameters are tuned using Ziegler-Nichols method and direct synthesis method respectively. The control loop performance of the control of third order process is improved with optimized parameters of PI controller. In direct synthesis method, the variable parameter of PI controller is obtained with Genetic algorithm. The controller parameter of PI controller is obtained from optimized variable parameters and results are reveals that the performance of closed loop is enhanced with the elimination of peak overshoot and minimization of oscillation levels in the process variables. Simulation results are confirmation that the proposed design method is better to the Ziegler-Nichols method and direct synthesis method. Furthermore, the proposed method was applied to the control of two different categories of third order processes.

Automatic Generation Control of Two-Area STThermal Power System using Jaya Algorithm

This article present automatic generation control (AGC) of a two area thermal system incorporating solar thermal power plant (STPP) in one of the areas. The performance of the conventional two area system is compared with the proposed system. Similarly, the performances of integral (I), proportional plus integral (PI), and proportional plus integral plus derivative (PID) controller are evaluated in the system with STPP. For optimization of the proposed system, a new optimization technique, i.e. Jaya Algorithm is used for the optimization of secondary controller gains. Examinations uncover that Jaya optimized PID controller’s performance is better as compared to integral and proportional integral control. Better dynamic performances like settling time, overshoot, undershoot is achieved by Jaya algorithm for the proposed system. Further, robustness of the systems are studied by changing all the system parameter from -25% to 25%. Analysis reveals that Jaya algorithm based PID controller gains are quite robust and need not be reset for large variations in system parameters.

Design and Tuning of Robust Fractional Order Controller for Autonomous Microgrid VSC System

A robust controller design for the voltage control of an autonomous three-phase voltage source converter (VSC) is proposed. As compared with the conventional proportional plus integral (PI) controllers, fractional order controllers make the VSC system robust due to their fractional characteristics. The fractional PI $\lambda$ controller has an additional degree of freedom $\lambda$ along with $k_p$ and $k_i$ gains of the conventional PI controller. Detailed modeling of a VSC is used in the controller design process so as it include inner current control and filter dynamics. The outer fractional voltage controller is designed such that the VSC system satisfies a required phase margin, with improved robustness in the system and capability to attenuate the noise. The overall system stability is analyzed using both bode plot and step response, and these responses are compared with a conventional PI controller. Further, the dynamic performance of the fractional controller is evaluated by simulating the nonlinear system. A hardware prototype is also developed to demonstrate the practical realization of the controller.

Performance Analysis of a Nonlinear Coupled-Tank System Using PI Controller

In the process industry many of the control applications deal with liquid level, flow, temperature and pressure processes. This paper presents the approach of modeling and controller design of liquid level control system for a nonlinear Coupled-Tank System. First of all, the mathematical equations for the nonlinear system are explored. And then, proportional plus integral (PI) controller is designed to control the level of the second tank for the nonlinear model, through variable manipulation of water pump in the first tank. The simulation study is done using MATLAB and the performance analysis in time domain of the controller is identified. In addition, ITAE criterion is used to evaluate the controller performance. Finally, the simulation results indicate that the controller work very well and the proposed controller has the ability to reject the effect of the disturbance.

PI simultaneous stabilization and set-point output regulation of Port-Hamiltonian systems

This paper is concerned with the problems of simultaneous stabilization and set-point output regulation of N Port-Hamiltonian (PH) systems. First, incremental models of PH systems are constructed and the passivity of incremental systems is established with some reasonable assumptions. Then a proportional plus integral (PI) controller is proposed to simultaneously stabilize incremental systems, and the stability of the closed-loop system is proved by Lyapunov function approach. The simple case with two PH systems is studied emphatically, and the obtained results are also naturally extended to the general case of N PH systems. Finally, the validity and applicability of the proposed PI controller is verified through an illustrative example.

Decoupled self-tuning PI controller for an idling stop system applied to scooters

This paper is aimed to propose a decoupled self-tuning proportional plus integral (PI) controller with simple law for an idling stop system applied to scooters. An integrated starter generator (ISG) of the idling stop system is designed with a high efficiency permanent magnet synchronous motor (PMSM). The PMSM used as an ISG must have a high torque characteristic to ensure that the engine can be accelerated up to firing speed. A conventional and useful control algorithm named PI control is unable to handle motor current very well for dynamic load, parametric variation, and external disturbance, especially in a vehicle application. Therefore, a robust algorithm for current control in an ISG is proposed. The decoupled selftuning PI controller based on the Lyapunov stability theorem is utilized to guarantee the control performance. Numerical simulations demonstrate the effectiveness of the proposed control algorithm. Experimental results show that the engine of a 150 cm3 scooter can be cranked to reach firing speed by a ISG within 0.1−0.2 second. The proposed method is simple, robust, as well as stable for idling stop system, and can be effectively implemented.

Control of a Grid-Forming Inverter Based on Sliding-Mode and Mixed ${H_2}/{H_\infty }$ Control

A grid-forming inverter (GFI) is an important component for the operation of an islanded microgrid. Its purpose, similar to a conventional slack bus generator, is to build up a reference voltage for other distributed generating units in the microgrid. Usually, a nested-loop proportional plus integral (PI) control structure is employed to control a GFI in a $dq$ reference frame. However, conventional PI-based nested-loop control method has a deteriorative performance under parameter variations. In this paper, a novel nested-loop control strategy is proposed for control of a GFI system containing an ${LC}$ output filter and loads. The proposed method does not require a precise model for the inverter system and can better deal with uncertainties and ${LC}$ filter resonance without using any passive or active damping mechanisms. It utilizes a sliding-mode control in the inner current loop and a mixed ${H_2}/{H_\infty }$ optimal control in the outer voltage loop, which provides the advantages of constant switching frequency, low total harmonic distortion, robustness against parameters variations, and fast transient response. The simulation and hardware experiments presented in this paper demonstrate the proposed controller's improved transient and steady-state performance in various key criteria, over conventional PI-based nested-loop control strategy.

Design and implementation of closed-loop control system for buck converter using different techniques

Comparing between different techniques for the design and implementation of closed-loop control systems for buck converters is carried out. Controllers used for this comparison are integral, proportional plus integral (PI) controllers and artificial intelligence are represented in fuzzy logic controller (FLC) and tuned fuzzy logic controller (TFLC). Design and implementation of a control system demand the role of effective techniques that offer simple and pragmatic solutions in society to meet the performance requirements despite system disturbances and uncertainties [1]. The occurrence of nonlinear phenomena in buck converters makes their analysis and control difficult [2]. Classical linear techniques have stability limitations around the operating points [1]–[3]. Hence digital and nonlinear stabilizing control methods must be applied to ensure large-signal stability [3]. Fuzzy control has also been employed to control buck converters because of its simplicity, simplicity of design and simplicity of implementation [4], [5]–[10]. Fuzzy controllers are easily suited to nonlinear time-variant systems and do not require an accurate mathematical model for the system being controlled. They are usually designed based on expert knowledge of the converters [5]. In this survey, the design procedures of integral, proportional plus integral, fuzzy logic, and tuned fuzzy logic controllers are presented.

Comparison of GA tuned fuzzy logic and NARMA-L2 controllers for motion control in 5-DOF robot

Robots are useful in industries in many ways. In today’s economy, the manufacturing industry needs to be efficient to cope with the competition. Installing robots in the industry is often a step to be more competitive because robots can do certain tasks more efficiently than humans. Some of the manufacturing tasks in which robots perform better are assembling products, polishing, and cutting. In order to accurately perform these industrial operations, an effective controller needs to be implemented instead of conventional Proportional plus Integral (PI) controller. When a fuzzy controller is implemented directly, there will be a problem of computational complexity. Therefore, soft computing-based approach namely, genetic-fuzzy systems are proposed in this paper. Fuzzy systems have been integrated with Genetic Algorithm (GA) to optimize the scaling factors that define the fuzzy systems. GAs inspired by the process of biological evolution, are adaptive search and optimization algorithms. A system to be optimized is represented by a binary string which encodes the parameters of the system. This methodology is highly robust and imprecision tolerant. If a unique optimum exists, the procedure approaches it through gradual improvement of the fitness and if the optimum is not unique, the method will approach one of the optimum solutions. Hence, GA tuned fuzzy system is proposed and compared with NARMA-L2 controller for controlling the motion of a 5DOF robotic manipulator. This analysis has been performed using SOLIDWORKS and MATLAB/SIMULINK environments.

A Novel and Simple Hybrid Fuzzy/PI Controller for Brushless DC Motor Drives

A novel speed controller for the trapezoidal three--phase Brushless DC (BLDC) Motor Drive is proposed using a hybrid fuzzy logic and proportional plus integral (PI) control. The fuzzy logic control structure is different from conventional fuzzy logic implementations such that it only uses three simple rules based on speed error being either in the positive, negative or zero regions. The controller outputs a reference current, that is enforced through the motor phases by pulsewidth modulation (PWM) control. The proposed fuzzy logic controller can be used individually in applications requiring lower computation load and accepting small steady state offset. For high performance applications requiring offset free tracking, a PI controller is augmented with the fuzzy logic controller and a simple switching scheme is devised based on error variance to switch the active controller based on operating conditions. The response of the drive system under the proposed composite control structure is compared with the conventional PI based and the sliding mode controllers to demonstrate its improved performance. Simulations studies using detailed models in MATLAB/Simulink's Simpowersystems toolbox are carried out to show the validity of proposed control.

Neural Adaptive Decentralized Coordinated Control with Fault-Tolerant Capability for DFIGs under Stochastic Disturbances

At present, most methodologies proposed to control over double fed induction generators (DFIGs) are based on single machine model, where the interactions from network have been neglected. Considering this, this paper proposes a decentralized coordinated control of DFIG based on the neural interaction measurement observer. An artificial neural network is employed to approximate the nonlinear model of DFIG, and the approximation error due to neural approximation has been considered. A robust stabilization technique is also proposed to override the effect of approximation error. A H2 controller and a H∞ controller are employed to achieve specified engineering purposes, respectively. Then, the controller design is formulated as a mixed H2/H∞ optimization with constrains of regional pole placement and proportional plus integral (PI) structure, which can be solved easily by using linear matrix inequality (LMI) technology. The results of simulations are presented and discussed, which show the capabilities of DFIG with the proposed control strategy to fault-tolerant control of the maximum power point tracking (MPPT) under slight sensor faults, low voltage ride-through (LVRT), and its contribution to power system transient stability support.

Controller Design for a Variable-Speed Direct-Drive Permanent Magnet Synchronous Generator-Based Grid-Interfaced Wind Energy Conversion System Using D-Partition Technique

In order to overcome the often encountered trouble in setting the controller parameters by trial and error, an attempt has been made to design the proportional-plus-integral (PI) controllers for a variable-speed direct-drive permanent magnet synchronous generator-based grid-connected wind energy system (WES). The characteristic equations for various control loops in WES have been developed, and the most stable zones have been identified in the parametric plane by means of the D-partition technique and frequency scanning check. To ensure high degree of relative system stability and good damping ratio, the PI controller parameters have been selected by comparing the step responses of the control loop plotted for different sets of controller parameters chosen from the identified stable zone. A simulation model using MATLAB/Simulink and SimPowerSystems toolbox has been built to examine the performance of the WES incorporated with the designed values of the parameters of the PI controllers under fluctuating wind speed condition.

An Efficient Robust Servo Design for Non-Minimum Phase Discrete-Time Systems with Unknown Matched/Mismatched Input Disturbances

This paper presents an efficient proportional-plus-integral (PI) current-output observer-based linear quadratic discrete tracker (LQDT) design methodology for the non-minimum-phase (NMP) discrete-time system with equal input and output number, for which the minimalized dynamic system contains the unmeasurable system state and unknown external matched/mismatched input disturbances. Illustrative examples are given to demonstrate the effectiveness of the proposed approach.

A new PI optimal linear quadratic state-estimate tracker for continuous-time non-square non-minimum phase systems

ABSTRACTBased on the proportional-integral-derivative (PID) filter-shaping approach, this paper presents a new proportional-plus-integral (PI) optimal linear quadratic state estimator (LQSE) for the continuous-time non-square and non-minimum phase (NMP) multivariable systems. Together with the recently developed optimal linear quadratic tracker (LQT), the proposed LQSE-based tracker is able to optimally achieve good minimum phase-like tracking performances for a non-square NMP multivariable system with unmeasurable states and arbitrary command inputs.

Performance Analysis of Boost Fed Dc Drive under Load Uncertainties

Objectives: To design a new converter topology based on boost converter to obtain essential control characteristics of a DC drive. Methods/Statistical analysis: The developments in power electronics based industry/technology and development in new converter design strategies, the speed of DC motor can be maintained at required level by maintaining the voltage across armature. The closed loop control scheme with proportional plus integral (PI) controller takes speed reference and the actual speed of DC motor as input parameters and generates the pulses to control the boost converter output voltage. Findings: With this, the speed of DC motor can be maintained at the required speed. The effectiveness of closed loop control scheme with PI controller is compared with that of open loop control scheme. The analysis presented in this paper is mainly concentrated to obtain the suitable operational changes pertaining to various input and output parameters such as output voltage, input and output currents, speed, torque and output powers are analyzed for different load uncertainties. The complete design procedure of converter, analysis of load uncertainties is presented with supporting graphical and as well as numerical results. Application/Improvements: This converter design procedure can be applicable to control the speed of DC motor as per the application. With this procedure, the ripple factor and the converter losses can be decreased which results in improvement of converter efficiency. Keywords: Boost Fed DC Drive, Closed Loop Operation, Converter Design, Converter Losses, Load Uncertainties

A Supervisory Control Algorithm of Hybrid Electric Vehicle Based on Adaptive Equivalent Consumption Minimization Strategy with Fuzzy PI

This paper presents a new energy management system based on equivalent consumption minimization strategy (ECMS) for hybrid electric vehicles. The aim is to enhance fuel economy and impose state of charge (SoC) charge-sustainability. First, the relationship between the equivalent factor (EF) of ECMS and the co-state of pontryagin’s minimum principle (PMP) is derived. Second, a new method of implementing the adaptation law using fuzzy proportional plus integral (PI) controller is developed to adjust EF for ECMS in real-time. This adaptation law is more robust than one with constant EF due to the variation of EF as well as driving cycle. Finally, simulations for two driving cycles using ECMS are conducted as opposed to the commonly used rule-based (RB) control strategy, indicating that the proposed adaptation law can provide a promising blend in terms of fuel economy and charge-sustainability. The results confirm that ECMS with Fuzzy PI adaptation law is more robust than ECMS with constant EF as well as PI adaptation law and it achieves significant improvements compared with RB in terms of fuel economy, which is enhanced by 4.44% and 14.7% for china city bus cycle and economic commission of Europe (ECE) cycle, respectively.

Fuzzy Tuned PI based Shunt Hybrid Power Filter for Power Quality Improvement

Objective:This paper explores the power condition abilities of Shunt Hybrid Power Filter (SHPF) with fuzzy tuned PI based control method in a distribution system. Method:A fuzzy tuner is proposed in this paper for tuning the parameters of proportional plus integral (PI) controller so that to improve the performance of the SHPF.The compensation process is based on source current sensing only. Synchronous Reference Frame(SRF) theory is used for generating reference currents, whereas linear current controller has been used to track these reference currents. Space Vector Pulse Width Modulation (SVPWM) has been employed to obtain the switching signals required for Voltage Source Converter (VSC). Findings/Improvements:Simulation analysis has been carried out to assess the performance of proposed control scheme. The simulation analysis proved that shunt hybrid power filters to be a potent solution for compensating the harmonics andreactive power of the distribution system.From the Simulation results, total harmonic distortion (THD), steady state response and dynamic behavior of the fuzzy tuned PI controller based SHPF is found to be better than conventional PI controller.