Gain Proportional Integral Controller Research Articles

Static output feedback LFC for semi‐Markov type interconnected multi‐area power systems: A non‐fragile PI strategy

AbstractThis article addresses the static output feedback load frequency control (LFC) problem for semi‐Markov type interconnected multi‐area power systems (IMAPSs) through non‐fragile proportional‐integral (PI) strategy. Primarily, by roundly exploiting the dynamical properties and considering random mutations of the IMAPSs, the semi‐Markov jump process (MJP) is elaborately scheduled for establishing the dynamical model with precision. Subsequently, on account of the characteristic of geographical isolation, a memory‐like sampled‐data LFC mechanism considering time‐varying transmission delay for the semi‐Markov jump IMPASs is formulated accordingly. Additionally, the non‐fragile issue is explored for the PI controller gain fluctuations to meet the actual operation scenario. After that, a mode‐dependent two‐side polynomial‐type looped Lyapunov functional is constructed for enhancing flexibility. Then, in virtue of the stochastic analysis technique, some relaxed conditions guaranteeing stochastic stability with prescribed performance are thereby derived in the shape of linear matrix inequalities (LMIs). Ultimately, a numerical example is carried out to validate the efficacy of the developed control methodology.

Optimizing renewable energy utilization with high gain converters

This research proposes a novel control technique for optimizing hybrid renewable energy sources (HRES) by using a high-gain DC-to-DC converter topology. The Hybrid RES system comprises a battery components, wind turbine (WT), and photovoltaic (PV). The proposed control methodology utilizes an enhanced jellyfish search (EJS) controller, which enhances the search behavior of the jellyfish search algorithm through the incorporation of mutation and crossover operators. The converter is designed to maximize efficiency, minimize switching losses, and effectively utilize renewable energy. To achieve optimal performance, a dataset with optimum gain values is constructed using a minimal error target function and proportional-integral (PI) controller gain parameters. The EJS algorithm determines the PI controller gain based on the error in reactive and active power. Randomly generated gain values are used as inputs to the system, and the algorithm adjusts the PI settings by minimizing system error and optimizing power flow management. The inclusion of batteries helps balance renewable power and enhances output consistency. The proposed system is implemented in MATLAB and is compared with existing systems. The novelty of this research lies in the combination of the EJS algorithm with converter efficiency, switching losses, and hybrid renewable energy sources. By utilizing the EJS algorithm, the proposed strategy has the potential to achieve superior outcomes based on cost savings, energy efficiency, and grid stability compared to conventional methods. Furthermore, the integration of this method contributes to the advancement of optimization algorithms and neural network applications.

Intelligent control of integrated on-board charger with improved power quality and reduced charging transients

This paper proposes an intelligent control scheme for a two-stage integrated onboard electric vehicle (EV) battery charger connected to a single-phase household outlet which offers a close to ideal battery charging profile with power factor correction feature. Generally, the front-end AC–DC​ conversion stage is controlled by dual loop proportional–integral (PI) controllers, and tuning their gain constants is a difficult task. Furthermore, to achieve a close to ideal charging profile for an EV battery, the DC–DC conversion stage switches from constant current (CC) and constant voltage (CV) mode after a certain state of charge (SOC) which may lead to discontinuity in the charging current and voltage. This paper attempts to solve these issues by proposing an intelligent control scheme that includes the dynamic estimation of PI controller gain constants as well as provides a seamless mode transfer feature for battery charging. It is achieved by using fuzzy-PI-based control in the AC–DC conversion stage and Bayesian Regularization (BR) algorithm trained artificial neural network (ANN)-based control in the DC–DC conversion stage. The performance of the proposed control scheme is assessed both in steady-state and transient conditions in MATLAB® Simulink environment by comparing it against similar control schemes. The proposed intelligent control approach improves the dynamic response of DC link voltage, offers unity power factor operation and maintains the line current harmonics within IEEE 519 standards even during the switchover from CC to CV charging mode. Also, there is a decrease of 85% in the third harmonic component of the source current, 23.2% improvement in DC link voltage undershoot and 6.5% reduction in DC link voltage overshoot with reduced settling times using the proposed unified control scheme.

Adaptive Observer for Dynamic Voltage Restorer with Optimized Proportional Integral Gains

An algorithm based on a sliding-mode adaptive observer is proposed for the effective control of dynamic voltage restorers (DVRs). Three single-phase voltage source converter-based topologies are implemented for the DVR. In this control, frequency adaption is considered for estimating the phase angle, system frequency, and fundamental component of the disturbed input voltage signals. The estimated fundamental component of the supply voltage is used to generate the DVR reference load voltage. The phase jump in the supply voltage is also considered for DVR compensation studies along with voltage sag, swell, and voltage distortions. For this purpose, the gains of the proportional integral (PI) controllers used in this control algorithm are estimated using a nature-inspired optimization approach for the desired response. A moth flame optimization algorithm is implemented for PI controller gain tuning owing to the advantage of finding the best solution by each moth's search and updating it. Through Matlab simulation and hardware testing, the performance of the DVR with an adaptive observer is found to be satisfactory for supply voltage sag, swell, phase jump, and voltage distortions.

Robust Load Frequency Control of Interconnected Power System in Smart Grid

In this paper, the coordinated control of vehicle to grid (V2G) power control and proportional-integral (PI) tuned with particle swarm optimization (PSO), based on H-infinity control, are integrated to control the frequency regulation of interconnected power system in Smart Grid (SG) environment. The plug-in hybrid electric vehicle (PHEV) can compensate the deficient load frequency control (LFC) capacity. In this way V2G power control is applied to compensate for the LFC capacity. For charging the batteries, power is supplied from grid-to-vehicle (G2 V). The traditional controller performance is compared for working with multiple uncertainty-based H∞ controllers and the results proved the predominant performance of the proposed control. To check the system robustness against uncertainty, the PI controller gain and State of Charge (SOC) deviation are optimized using the PSO-based multiple uncertainty-based H∞ controller. Different specimens have been analyzed to ensure the entire working of the developed model. A series of simulation results are presented for the dynamic response of power systems which is superior to other design methods obtained from the literature. Simulation results of two-area interconnected intelligent power system show that frequency deviations are minimal and within specified limits.

An Improved Result on Stability Analysis of Delayed Load Frequency Control Power Systems

This paper investigates the stability of power systems with load frequency control considering time delays (constant and time-varying delays). A new criterion for ensuring the stability of the system is proposed on the basis of Lyapunov stability theory and a further strengthened inequality. Finally, taking a single-area load frequency control scheme with the proportional-integral controller as an example, according to the stability criterion obtained, the relationship between the maximum allowable delay and the gain of proportional-integral controller is discussed. Besides, in case studies, the effectiveness of our method is also demonstrated.

Natural Genetics Adapted Control for an Autonomous Wind-Battery Based Microgrid

Autonomous microgrids supply power to large remote areas where access to the grid is infeasible. The generation of these microgrids is highly dominated by renewable energy resources (RESs) equipped with a storage battery. Due to the uncertainty associated with RESs, the sustainability and reliability of supply become the prime areas of focus. The battery reduces the uncertainty during demand rise, power deficiency, and overloading with their faster response than diesel generators and microturbines. In this article, the power generation of the isolated microgrid is considered from the wind energy source along with a battery. For the favorable speed regulation of the wind turbine driven generator, the traditional proportional integral (PI) controller is replaced by natural genetics [genetic algorithm (GA)] and evolution inspired PI controller. The issues identified by the use of a fixed gain PI controller such as unsuitable regulation due to incorrect tuning and discontinuous tuning are addressed by the use of a GA tuned speed controller. The performance of the PI controller degrades while dealing with the ac quantities, so in terms of dealing with sinusoidal signals, here an adaptive proportional resonant controller with a combined generalized integrator based phase locked loop is utilized. It tracks the reference ac voltage and provides frequency adaptation in the presence of harmonics pollution with zero steady state error. The batteries deployed through a bidirectional converter, act as the residential storage for backing up the power firming renewable production. The maximum power point (MPP) extraction of the wind generator is carried by a perturb and observe based MPP technique. The performance improvement obtained from the laboratory developed test setup verifies the microgrid effectiveness under renewable generation variability and load alterations.

Model-Based Current Control Strategy With Virtual Time Constant for Improved Dynamic Response of Three-Phase Grid-Connected VSI

In this paper, a model-based current control strategy with virtual time constant is proposed for three-phase grid-connected LCL-filtered voltage source inverters. The proposed control strategy is based on controlling the inverter currents in the rotating dq frame by using current-oriented proportional-integral (PI) controllers rather than voltage-oriented PI. The PI controllers determine the inverter current references in the d- and q-axes by regulating the grid current. It is shown that the proposed strategy decouples the inverter current from other variables provided that the inverter-side inductance and its resistance values used in the control variable match the actual values in the system. In addition, the virtual time constant is introduced in the control variables to offer flexibility for adjusting the inverter current dynamics as desired. Moreover, the integral gain of PI controller has the ability to keep the LCL-resonance peak below 0 dB. Unlike the existing methods, the proposed strategy does not require a dedicated active damping. Computer simulations and experimental studies show that the proposed control strategy exhibits a good performance in achieving fast dynamic response and sinusoidal grid current with low THD under balanced, unbalanced, and distorted grid conditions.

Dynamic modeling, adaptive control and energy performance simulation of a hybrid hydronic space heating system

A dynamic model of a hybrid hydronic heating system has been developed. The overall model consists of a boiler, a heat exchanger, a ground loop heat pump, a ground loop heat exchanger, baseboard heaters (convector–radiators), and radiant floor hydraulic piping system. Two control strategies for improving the overall system performance were explored: (1) a conventional proportional-integral (PI) control and (2) an adaptive gain control. The simulation results showed that the performance of the adaptive controller is better than the fixed gain PI controller in disturbance rejection and stability. Energy simulations under three different operating strategies were conducted: (1) a fixed set-point PI control, (2) an outdoor air temperature reset control, and (3) an optimal set-point adaptive PI control. It was shown that the outdoor temperature reset strategy can save 4.5 and 19.9% energy under cold day and mild day conditions compared to the fixed set-point PI control strategy. The optimal adaptive PI control strategy resulted in higher energy savings of 6.6 and 22% as compared to the PI control under cold and mild day conditions, respectively. Practical application: Energy efficiency and sustainability are a major issue of importance in the design and operation of space heating systems. The proposed hybrid system combines a ground-source heat pump and a hot water boiler for space heating of both residential and commercial building applications. The heating system consists of radiant floor piping for the residential zones and hot water baseboard heaters (convector–radiators) for the commercial zones. An energy optimal adaptive control strategy is designed to improve energy efficiency and temperature control performance of the hybrid system. The control strategy is simple and can be implemented on the existing building control systems.

A Discrete Delay N-decomposition Approach for Delay-Dependent Stability of Generator Excitation Control System with Constant Communication Delays

<p>This paper deals with problem of delay in stability analysis of network controlled generator excitation system. Delays exist in communication channel in network based control between system and controller. A discrete delay N-decomposition is used to compute delay margin for generator excitation system with constant delay which is easier when compared to analytical method. A Lyapunov krasovskii function is constructed for given time delay generator excitation system and linear matrix inequalities techniques are used. Generator excitation system is employed with proportional integral controller, delay margin calculated for various values of gain of proportional integral controller. Theoretically obtained results are verified using simulation studies.</p>

Application of modular multilevel converter for AGC in an interconnected power system

Abstract This article demonstrates the maiden application of a new Modular Multi level Converter based Series Compensation (MMCS) technique for multi area Automatic Generation Control (AGC) interconnected system. Primarily MMCS has been modeled in state space form and proposes an appropriate location in AGC to obtain the better dynamic responses in frequency, tie-line power and individual generating power; further to quench the oscillation for sudden changes in load. The system has been studied the operation of MMCS and investigated with Generation Rate Constraints (GRC) of reheat turbines used in system. Further, selection of suitable integral and proportional–integral controller gain has been investigated with Integral Square Error (ISE) technique and Particle Swarm Optimization (PSO) technique for step load perturbation (SLP) in area-1 with performance index as its objective function by making control parameters as variables. System with MMCS is compared with out MMCS and observed performance has been increased and results are explored.

Space Vector Pulse Width Modulation Based Indirect Vector Control of Induction Motor Drive

This paper presents the implementation of a different SPACE VECTOR PWM techniques applied to the indirect vector controlled induction motor (IM) drive involves decoupling of the stator current into torque and flux producing components of an induction motor. The drive control generally involves a fixed gain proportional-integral controller. Space vector pulse width modulation technique is widely used in inverter and rectifier controls. Compared to the sinusoidal PWM (SPWM), SVPWM is more suitable for digital implementation and can increase the obtainable maximum output voltage with maximum line voltage approaching 70.7% of the DC link voltage (compared to SPWM’s 61.2%) in the linear modulation range. This paper presents the indirect vector controlled induction motor drive using different Space Vector PWM techniques are implemented in MATLAB-SIMULINK. The corresponding harmonic spectrum is calculated for various PWM techniques and the results are compared.

Experimental verification of Hopf bifurcation in pulse‐width modulated inverter fed cage induction motor drive system

Bifurcation theory deals with the change of qualitative behaviour in a parameter space of dynamical systems. This study investigates the bifurcation phenomenon of an industrial drive having typically constant speed requirement for which pulse-width modulated inverter fed cage induction motor (IM) is a good choice. The focus is on bifurcation analysis of the stator voltage controlled IM drive, with a particular emphasis on the dynamics and stability under variations of load torque and proportional integral controller gain. Extensive computer simulations are performed to capture the system´s dynamic behaviour and demarcate the bifurcation boundaries. Trajectory and Poincare section before and after the bifurcation are shown. The detailed mathematical model of the closed-loop system is derived and is used to analyse the observed bifurcation phenomena. The describing equations reveal that the system loses stability via supercritical Hopf bifurcation. Experimental results are also provided to confirm the theoretical analysis.

Design of Multicarrier Pulse Width Modulation based Cascaded Multilevel Inverter for STATCOM using Bats Echolocation Controller

A Static Synchronous Compensator (STATCOM) is one of the Flexible AC Transmission System (FACTS) device which plays an vital role in power system network in alleviation of small and large transient disturbances and better voltage regulation. This paper proposed a self tuning Proportional-Integral (PI) controller for STATCOM which provided a voltage support at point of common coupling (PCC). Self tuning of PI controller was achieved by adapting PI controller gains with system parameters by using Bats Echolocation controller which mimics the Bats Echolocation behavior. In the proposed controller, the system voltage (parameter) at point of common coupling compared with reference voltage and then Bats Echolocation Controller updates the PI controller gains according to the variation obtained between them. This paper also proposed a Cascaded Multilevel Inverter (CMLI) instead of conventional Voltage Source Inverter (VSI) for STATCOM to obtain better voltage regulation at point of common coupling. The voltage imbalance between H-bridge cells in CMLI was rectified by prosing Multicarrier Pulse Width Modulation (PWM) techniques, The proposed controller was validated by comparing the simulation results with fixed gain PI controller and Self tuning PI controller using Neural controller and Particle Swarm Optimization.

An exhaust gas recirculation control strategy for passenger car diesel engines using an inverse valve model

In diesel engines, accurate control of the exhaust gas recirculation (EGR) is important because of its effects on the nitrogen oxide and particulate matter emissions. The conventional EGR control system adopts a simple proportional–integral (PI) control algorithm with a lookup-table-based feedforward control and gain scheduling. However, this lookup-table-based control system has limited control performance in transient operations because the lookup tables are obtained from static engine data. The objective of this paper is to improve the control performance of the diesel engine EGR system by using a mathematical model of the EGR path. The proposed EGR control system is composed of PI controller gain scheduling and a feedforward control algorithm based on the mathematical model. The gain-scheduling algorithm provides a PI controller gain based on a sensitivity function that elucidates the relationship between the effective flow area of the EGR valve and the EGR mass flowrate. The feedforward algorithm calculates the EGR valve position based on the inverse model of the EGR valve. The driving cycle test result showed that, compared with the conventional EGR control system, the r.m.s. and maximum values of the target tracking error were reduced by 2.5 per cent and 8.0 per cent respectively.

Speed sensorless field-oriented control of induction motor with interconnected observers: experimental tests on low frequencies benchmark

Field-oriented speed control of induction motors (IMs) without mechanical sensors (speed sensor and load torque sensor) are considered. The methodology is divided into two parts. First, interconnected high-gain observers are designed to estimate the mechanical and magnetic variables from the only measurement of stator current. Secondly, the speed and flux estimation are used by a controller to achieve the speed/flux tracking. The flux regulation problem is simple and the traditional approach is followed by using proportional integral (PI) controller. For the speed-regulation problem, it is stated that flux regulation quickly happens by using a high- gain PI controller to regulate the g-axis current to its reference. Stability analysis based on Lyapunov theory is proved to guarantee the 'observer + controller' stability. To test and validate the controller-observer by considering the sensorless control problem of IM at low frequency, a significant benchmark is implemented. The trajectories of this benchmark are designed to validate the controller and observer under three operating conditions: low speed, high speed and very low speed. Furthermore, robustness tests with respect to parameter variations are given in order to show the performance of the proposed observer-controller scheme.