Gain PI Controller Research Articles

Force-controlled Compensation Scheme for P-Q Valve-controlled Asymmetric Cylinder used on Hydraulic Quadruped Robots

Under the requirement of the force controller of hydraulic quadruped robots, the goal of this work is to accurately track the force commands at the level of the hydraulic drive unit. The main contribution focuses on the development of a force-controlled compensation scheme, which is specifically aimed at the key issues affecting the hydraulic quadrupedal locomotion. With this idea, based on a P-Q valve-controlled asymmetric cylinder, we first establish a mathematical model for the hydraulic drive unit force control system. With the desired force commands, a force feed-forward algorithm is presented to improve the dynamic performance of the system. Meanwhile, we propose a disturbance compensation algorithm to reduce the influence induced by external disturbances due to foot-ground impacts. Afterwards, combining with a variable gain PI controller, a series of experiments are implemented on a force control performance test platform to verify the proposed scheme. The results demonstrate that the force-controlled compensation scheme has the ability to notably improve the force tracking accuracy, reduce the response time and redundant force.

Control of Parallel AC Voltage Source Converter High-Voltage DC System Using an Adaptive PI Evolutionary-Based Controller

High-voltage direct current (HVDC) transmission system based on voltage source converter technology gains attraction in recent years for the grid integration due to many advantages like connecting wind farms to power grids, underground power links, connecting asynchronous grids, and providing efficient long-distance power transmission, etc. To acquire the best output from the above topologies, it is crucial to design a better controller strategy for the converter control. With this objective, this paper presents an adaptive PI controller based on evolutionary optimization for a parallel AC voltage source converter HVDC system. Looking at the extensive application of constant gain PI controller type, an adaptively changing gain parameter PI controller based on tan hyperbolic (tanh) function is proposed in this study. To enhance further its performance, a Modified Teaching Learning-Based Optimization (MTLBO) is used to find optimally the parameters of the proposed control strategy. To justify the effectiveness of the proposed controller, different test cases in terms of faults, parameter variation, and load & reference power variation are studied and analyzed. Comparative analysis with a conventional tuned PI controller, PI-MTLBO controller, and proposed API-MTLBO controller is demonstrated for indicating a substantial improvement in the damping system oscillations with better controllability and stability of the proposed approach.

Performance Investigation of Quasi Z Source Inverter (QZSI) Fed Induction Motor (IM) Drive System with bGWO-RDF Technique

In this dissertation, a hybrid strategy is intended for performance investigation of Quasi Z Source Inverter (QZSI) fed Induction motor (IM) drive system. The hybrid strategy is the fusion of both the binary version of grey wolf optimization (bGWO) and random decision forest (RDF) and commonly called as bGWO-RDF technique. The main contribution of the dissertation is to control the QZSI for enhancing the stability and the performance of IM drive system using the proposed hybrid strategy. The input of the proposed strategy is the speed and three phase current of IM. With the help of input parameters like actual speed and reference speed of IM, the PI controller gain parameters are optimized using bGWO technique. In order to train the RDF, the PI controller output like reference quadrature axis current and actual quadrature axis current is chosen. By utilizing the RDF, the reference three phase current is generated. By utilizing the actual and reference three phase current, the control pulses are generated at the final stage. Finally, the proposed technique is executed in the MATLAB/Simulink working platform. The effectiveness of the proposed is compared with various existing techniques such as ANN, PSO, PSO-SVM and GSA-SVM. The effectiveness of the proposed and other existing techniques is analyzed in terms of ripples and harmonics reduction, rise time, settling time and steady state error. Furthermore, the statistical analysis is also performed and compared with other existing techniques. The comparison result reveals that the total harmonic distortion (THD) is decreased and the oscillation period of the stator current, torque and speed are eliminated.

Optimal DTC Control Strategy of DFIG Using Variable Gain PI and Hysteresis Controllers Adjusted by PSO Algorithm

This paper presents an optimal Direct Torque Control (DTC) strategy for Doubly Fed Induction Generator based wind turbine. The proposed strategy is considered based on Particle Swarm Optimization (PSO) Algorithm. The PSO is found to be robust and fast in solving nonlinear problems. Motivation for application of PSO approach is to overcome the limitation of the conventional controllers design, which cannot guarantee satisfactory control performance when designed by trial and error. In this work PSO algorithm was used to adjust the hysteresis torque and flux comparators bandwidths and to tune the parameters of Variable Gain PI (VGPI) controller designed for Maximum Power Point Tracking (MPPT) speed control of wind turbine to ensure high performance torque control. The optimal control strategy is considered in detail and it is shown that the use of the optimized controllers reduces rotor flux and electromagnetic torque ripples and improves the system dynamic performances. The effectiveness of the proposed direct torque control based on PSO algorithm (optimal DTC) method is illustrated through simulations on 1.5 MW DFIG based wind turbine. Simulation results illustrate the improved performances of optimal DTC compared with the conventional DTC.

Fuzzy-Variable Gain PI Mode Control Applied to a Brushless AC Motor Drive

More strategies were developed to control a Brushless Motor’s Speed. Among them, vector control is one of widely used. Variable Gain PI controller is developed and gives a performed control result. Fuzzy logic control is proposed to optimize the control system. In this paper, the system combines the performance of the Variable Gain PI and fuzzy logic controllers. All these strategies were simulated with Matlab and Simulink for comparison. Behind this, the main objective is to improve the best performance of the Fuzzy-Variable Gain PI mode control applied to a Brushless AC Motor drive where implementations, to an MSK23335 Board with a PM50 module and a 90W BLAC Motor, are shown to improve the result.

PID Temperature Control of Demineralized Water Tank

This paper presents a temperature control of demineralized water tank system, which is widely used in industrial processes. Theoretical modeling of temperature demineralized water tank has been study by applying mass and energy balance. Results of model have been compared with experimental data. PID controller is used to control the temperature inside the process tank within operating condition. Ziegler-Nichols and Tyreus-Luyben have been used to find parameters (proportional gain, integral time and derivative time) of PI and PID controller. Integral Absolute Error (IAE) and Integral Square Error (ISE) are used to compare between performances of the controllers. The results show that PID Controller gives better performance than PI Controller for the temperature control system.

Grid Connected Control Strategy of Microgrid

The Combination of large power grid and distributed power supply is recognized by electric power experts as the development direction of power industry, which can save energy consumption, improve the reliability and flexibility of power system. Therefore, it is of great value to study distributed power supply. According to the shortcomings of PI control gain at the fundamental frequency of small, poor control effect, introducing the band-pass quasi PR controller, and improve the algorithm in order to improve the control effect, and finally through the MATLAB simulation software to test the improved algorithm, verify the feasibility of the algorithm and accuracy.

A new self-adjusting PI controller for power control in a wind turbine generator

PurposeThe purpose of this paper is to propose a novel self-adjusting proportional integral (SA-PI) controller, for controlling the active and reactive power of permanent magnet synchronous generator (PMSG) when subjected to variable wind speed and parameter variations.Design/methodology/approachThe proportional and integral gains of the proposed SA-PI controller are based on tan-hyperbolic function and adjust themselves automatically within pre-fixed limits according to the error occurring during transient situations.FindingsThe proposed SA-PI controller is able to evade the problems usually encountered while using a constant gain PI controller, such as lack of robustness, adaptability and a wide range of operation. It also damps out system oscillations faster with reduced settling time and fewer overshoots.Originality/valueSimulation results and comparative studies with conventional PI controller and the differential evolution–optimized PI (DE-PI) controller reveal the effectiveness of the proposed control scheme. MATLAB is used to perform the simulation studies.

DESIGN, ANALYSIS AND EXPERIMENTAL VERIFICATION OF A NOVEL NONLINEAR PI CONTROLLER

In this study, a novel variable gain PI controller structure is introduced. The proposed controller structure consists of a sector-bounded nonlinear function of the relative error value in cascade with a linear fixed-gain PI controller. The stability analysis of the closed loop system is examined through Popov stability criterion, Routh-Hurwitz stability method and stability boundary locus method for both second-order and higher-order systems. In addition, the performance of the controller against parameter variations and disturbances is investigated through some simulations for second order systems. An experimental study, an active suspension system, is conducted to examine the performance of the controller for higher order systems. In the literature, there are similar controllers, but the proposed one is superb in terms of effectiveness and stability. The new controller prevents the saturation of the controller signal. Simulation results and experimental studies reveal that proposed controller structure is quite effective for both lower and higher order systems.

Design and Development of Self Tuning Controller for TCSC to Damp Inter Harmonic Oscillation

The disturbances occurring in a power system induce electromechanical oscillations of the electrical generators. These oscillations, also called power swings, must be effectively damped to maintain the system's stability. The aim is to mitigate power oscillations in power systems. There is currently interest in using Thyristor controlled series capacitors (TCSC) in transmission lines for the dual purpose of altering the steady-state power flow and enhancing system stability. Thyristor controlled series capacitors (TCSC) is one of the typical FACTS device which is used to improve the voltage profile and transient stability in power system by damping the frequency oscillation in it. This paper describes an adaptive method for control of a TCSC device for power oscillation damping. In this paper, a self-tuning PI controller for Thyristor Controlled Series Capacitor (TCSC) is proposed. Simulation results illustrate the effectiveness of the proposed self-tuning controller in simultaneously damping local-mode and inter-area oscillations. Results are compared with the fixed gain PI controller and Self-tuning PI controllers.

外乱抑制FRIT法を用いたPI制御ゲインチューニングの浮体式洋上風車への応用

Floating offshore wind turbines (FOWTs) have attracted interest in recent years. FOWTs operate under irregular wind and waves, and these disturbances cause generator output fluctuation and platform motions. In this paper, a PI controller in collective blade pitch control is used to mitigate these fluctuation and motions. The PI controller gain parameters are tuned by the FRIT (Fictitious Reference Iterative Tuning) method, and we design a gain-scheduled PI controller based on tuned gains at multiple operating points. We show that the gain-scheduled PI controller improves the disturbance suppression performance.

An extension of the Georgiou–Smith example: Boundedness and attractivity in the presence of unmodelled dynamics via nonlinear PI control

In this paper, a nonlinear extension of the Georgiou–Smith system is considered and robustness results are proved for a nonlinear PI controller with respect to fast parasitic first-order dynamics. More specifically, for a perturbed nonlinear system with sector bounded nonlinearity and unknown control direction, sufficient conditions for global boundedness and attractivity have been derived. It is shown that the closed loop system is globally bounded and attractive if (i) the unmodelled dynamics are sufficiently fast and (ii) the PI control gain has the Nussbaum function property. For the case of nominally unstable systems, the Nussbaum property of the control gain appears to be crucial. A simulation study confirms the theoretical results.

Harmonic Currents Extraction Techniques for a Fix and Adaptive Fuzzy Hysteresis Controlled Shunt Active Power Filter

The main objective of this paper is to focus upon the comparison of three of harmonic current extraction techniques, based on harmonic mitigation and power quality improvement. The first method is direct control based on sliding mode control (SMC). The two others use respectively the instantaneous real and imaginary powers theory (p-q) and self-tuning filter (STF) with a conventional constant gain PI controller for the DC voltage regulation to optimize the energy storage of the DC capacitor. A fix hysteresis and an adaptive fuzzy hysteresis band current control techniques are used to generate the switching signals of the shunt Active Power Filter (SAPF). Simulation results using MATLAB/SIMULINK/Power System highlighted performances and limitations of each proposed algorithms and also show effectiveness of the fuzzy logic control which gives flexibility and high dynamic performances.

A Certain Investigation on Harmonic Reduction and Design of Fuzzy Gain Scheduler for Shunt Compensation for Power Quality Enhancement

Abstract This article describes a Synchronous reference frame based current control scheme for three phase shunt active power filters (SAPFs) to reduce or to remove harmonics, correct power factor, and balance asymmetrical load is analyzed. This active power filter (APFs) is used to compensate harmonic currents and reactive power generated from the nonlinear loads. In this article, to determine reference compensation currents under balanced source voltages, the voltage source inverter for harmonic filtering of a three phase shunt active filter is used. In this proposed method, a fuzzy gain scheduling controller is used and the response of the DC link voltage is compared with PI controller during transient and steady state. The main objective of this article is to analyze shunt active filters with fuzzy gain scheduling controllers and PI controllers. To carry out this analysis, active and reactive current methods (Id–Iq) are considered. Extensive simulations were carried out. The simulations were performed under balance sinusoidal conditions. The results validate the dynamic behavior of a fuzzy gain scheduling controller over PI controllers. The simulation of the proposed system is evaluated using MATLAB Simulink and the results show that the proposed method is more effective than the existing methods.

ANFIS and MRAS-PI controllers based adaptive-UPQC for power quality enhancement application

This paper presents a novel heuristic based adaptive control technique (ACT) for improved compensation capability of the unified power quality conditioner (UPQC). The compensation capability of UPQC is enhanced by the optimal regulation of DC link voltage. Among all power quality (PQ) distortions, voltage sag is the severe PQ problem that significantly deteriorates the regulation of DC link voltage. The conventional approaches utilize a fixed gain PI controller that increases the error between the reference and actual DC link voltage under sag condition. This ultimately results in poor compensation of PQ distortions at the point of common coupling. To enhance compensation capability, the performance of ACT is examined with analytical and artificial intelligence techniques. The model reference adaptive system (MRAS) is used in the analytical method for online self tuning PI controller. For artificial intelligence technique, the off-line trained ANFIS is processed in the simulation studies. The performance of ACT based UPQC is validated in Matlab/Simulink and the obtained results are compared with conventional scheme. To substantiate theoretical results of the proposed approach, the algorithm is tested in real time Xilinx system generator (XSG).

High Performance PI Current Controller for a Switched Reluctance Motor

The most common current controller for the Switched Reluctance Motor (SRM) is the hysteresis controller. This method, however, suffers from such drawbacks as variable switching frequency, consequent audible noise and high current ripple. These disadvantages make this controlling method undesirable for many applications. The alternative solution is the PI controller. Since the fixed gain PI current controller can only be optimized for one operating point, and on the other hand, SR motor is highly nonlinear, PI controller gain should be adjusted according to incremental inductance. This paper presents a novel method for PI current controller gain adaptation which is simple and yields a good performance. The proposed controller has been implemented on a test bench using a eZdsp F28335 board. The performance of the current controller has been investigated in both simulation and experimental tests using a four-phase 8/6 4KW SRM drive system.

Optimization of PI Controller Gain for Simplified Vector Control on PMSM Using Genetic Algorithm

This paper proposes the used of genetic algorithm for optimizing PI controller and describes the dynamic modeling simulation for the permanent magnet synchronous motor driven by simplified vector control with the aid of MATLAB-Simulink environment. Furthermore, three kinds of error criterion minimization, integral absolute error, integral square error, and integral time absolute error, are used as objective function in the genetic algorithm. The modeling procedures and simulation results are described and presented in this paper. Computer simulation results indicate that the genetic algorithm was able to optimize the PI controller and gives good control performance of the system. Moreover, simplified vector control on permanent magnet synchronous motor does not need to regulate the direct axis component current. This makes simplified vector control of the permanent magnet synchronous motor very useful for some special applications that need simple control structure and low cost performance.

Design of Robust Speed Controller by Optimization Techniques for DTC IM Drive

Direct Torque Control (DTC) of induction motor is preferred control strategy recently, due to its quick torque response, simplicity, less sensitivity against motor parameter variation. In general, PI speed controllers are widely used in industrial applications due to their simple structure. Due to the continuous variation of machine parameters, model uncertainties, nonlinear dynamics and system external disturbance, fixed gain PI controllers may becomes unable to provide the required control performance. Genetic Algorithm (GA) is used to tune the PI controller gains to ensure optimal performance. GA is more attractive for applications that involve non smooth or noisy signals. GA is used to minimize speed error and attains optimal values of the PI controller gains. The efficient and effective speed controllers can be designed by using adaptive control techniques. In which the conventional PI controller is replaced by structures based on Sliding Mode Control (SMC) strategy. SMC is known for its capability to cope with bounded disturbance as well as model imprecision which makes it ideal for the robust nonlinear control of IM drives

Variable Gain PI Controller Design For Speed Control of a Doubly Fed Induction Motor Using State-Space Nonlinear Approach

This paper presents a comparison between a variable gain PI controller and a conventional PI controller used for speed control with an indirect field orientation control of a Doubly Fed Induction Motor (DFIM), fed by two PWM inverters with a separate DC bus link. By introducing a new approach for decoupling the motor’s currents in a rotating (d-q) frame, based on the state space input-output decoupling method, we obtain the same transfer function (1/s) for all four decoupled currents. Thereafter, and in order to improve control performance, the VGPI controller was used for speed regulation. The results obtained in Matlab/Simulink environment illustrate the effectiveness of the technique employed for the decoupling and for speed regulation.

SC-FNPI 제어기를 이용한 IPMSM 드라이브의 효율최적화 제어

This paper proposes the efficiency optimization control of interior permanent magnet synchronous motor(IPMSM) drive using series connected- fuzzy neural network PI(SC-FNPI) controller. The PI controller is generally used to control IPMSM drive in industrial field. However, the PI controller has problem which is falling control performance about parameter variation such as command speed, load torque and inertia due to fixed gain of PI controller. Therefore, to improve performance of PI controller, this paper proposes SC-FNPI controller adjusted input of PI controller by FNN controller according to operating conditions. Also, this paper proposes efficiency optimization control which is improving efficiency with minimize loss. The SC-FNPI controller proposed in this paper is compared control performance with conventional FNN and PI controller about command speed, load torque and inertia variation. And the efficiency optimization control is compared with i<SUB>d</SUB> = 0 control about loss and efficiency. The SC-FNPI controller proposed in this paper shows more excellent control performance for rising time, overshoot and steady-state error. Also efficiency optimization control is increased efficiency by reducing loss.