Suboptimal Control of Singularly Perturbed Two Parameter Discrete Control System

Authors: G. KISHORE BABU    and M. S. KRISHNARAYALU

Abstract

A singularly perturbed discrete power system with two parameters (three-time-scales) is considered. An optimal controller using Pontriagin’s minimum principle (PMP) is designed for this stiff system. But the solution for control law of this type of system requires special numerical techniques such as shooting methods. Hence it is better to go for a suboptimal controller that eliminates this problem. Singular perturbation method (SPM) that reduces the order, removes the stiffness of the system and with approximate solutions closer to optimal solution is an ideal choice for this problem. The SPM consists of an outer, two initial boundary layer corrections (BLC) and two final BLC solutions for this problem. The SPM is applied to a fifth order power system model as a case study. The results of case study validate the proposed suboptimal controller.

 

Index Terms

Two parameter discrete system, Open-loop optimal control, Stiff two-point boundary value problem, Suboptimal control, Singular perturbation method, Outer solution, Boundary layer corrections.

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Suboptimal Control of Singularly Perturbed Two Parameter Discrete Control System

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Comparison of Fuzzy PID Controller with Conventional PID Controller in Controlling the Speed of a Brushless DC Motor

Authors: S. Sunisith, Lizi Joseph and M. Saritha

Abstract

Brush less DC motors are widely used for many industrial applications because of their high efficiency, high torque and compact size. The proposed speed controlling technique used to control the speed of a brushless DC motor is based on proportional integral derivative controller and Fuzzy proportional integral derivative controller. This paper describes the overview of performance of conventional proportional integral derivative controller and Fuzzy proportional integral derivative controller. It is difficult to tune the parameters and get satisfied control characteristics by using normal conventional proportional integral derivative controller. As the Fuzzy has the ability to satisfy control characteristics and it is easy for computing in order to control the Brushless DC motor. Fuzzy proportional integral derivative controller is designed to control the speed of Brushless DC motor. The modeling, control and simulation of the Brush less DC motor have been done using the software package MATLAB to control the speed of Brushless DC motor. The results proved that a Fuzzy proportional integral derivative controller is better than Conventional proportional integral derivative controller.

Index Terms

Fuzzy Proportional Integral Derivative and Brushless DC Motor, Speed Control.

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Comparison of Fuzzy PID Controller with Conventional PID Controller in Controlling the Speed of a Brushless DC Motor

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Effective Algorithm for Reducing DC Link Neutral Point Voltage and Total Harmonic Distortion for Five Level Inverter

Authors: S. Sunisith,  K. S. Mann and Janardhan Rao

Abstract

The DC link Neutral Point Voltage balance problem is a permanent attribute in the Neutral Point Clamped multilevel inverters. DC link neutral point voltage can be balanced by keeping the upper and lower dc link capacitor voltages balanced for proper operation of Neutral Point Clamped multilevel inverters. In most respects, the balancing of neutral point voltage is dishonor at very low operating frequencies of the inverter. The earlier proposed methods of neutral point voltage balancing techniques result in an increase of switching losses and increase in cost of the inverter. In this paper, to solve the problem of DC link voltage unbalance, without increasing the switching losses a New Neutral Point Voltage Balancing method using SVPWM Technique is proposed and implemented for five level NPC inverter. This algorithm balances the dc link neutral point voltage without increasing switching losses of the devices. The proposed method is implemented in SIMULINK/ MATLAB using a list of SIMULINK blocks and MATLAB codes.

Index Terms

SVPWM, five level inverter, neutral point voltage, total harmonic distortion.

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Effective Algorithm for Reducing DC Link Neutral Point Voltage and Total Harmonic Distortion for Five Level Inverter

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Energy Capture Maximization from Distributed Generators in Rural Distribution Networks

Authors:S. Sunisith, N. Sridhar Reddy and K S Mann


Abstract

Voltage control problems are reported as one of the main obstacles against installation of large amounts of distributed generation. This research work is aimed to provide a voltage within the tolerable limits at all the nodes in the system when the system is connected with the distributed generation. The modern approach using consumer load control is discussed and compared with the existing methods using a simulation case study. Several methods like reducing primary substation voltage, constraining the generator operation are discussed. The voltage rise is more onerous when there is no demand on the system. In the proposed work, an algorithm for load flow study of radial distribution system is considered. Using the forward/backward sweep method, for the given typical radially tapered network voltage magnitude and phase angle at each bus are determined. This research discusses about the factors influencing voltage rise in a system like the connection point of the generator, rating of distributed generator, and network characteristic.

Index Terms

Distribution Network, Load flow methods, Distributed generator

 

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Energy Capture Maximization from Distributed Generators in Rural Distribution Networks

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AGC of an Interconnected Power System Using Fuzzy Logic Control

Authors: B. Prakash Ayyappan and  S. Bhagyashree

Abstract

Automatic generation control is a significant control process that operates constantly to balance the generation and load in power systems at a minimum cost. The AGC system is responsible for frequency control, power interchange and economic dispatch. This thesis reviews the main structures, configurations, modelling and characteristics of Automatic Generation Control systems in a interconnected power system and addresses the control area concept in interconnected Power Systems. With generation rate constraints (GRC) have been considered for the thermal and hydro plants. The design objective is to improve the frequency and tie line deviations of the interconnected system. The performance of FLC controller is compared with the results of Integral Squared Error (ISE) criterion based integral controller. Simulation results are presented to show the improved performance of FLC controller in comparison with the conventional integral controller. The results indicate that the controllers exhibits better performance. In fact, FLC approach satisfies the load frequency control requirements with a reasonable dynamic response.

 

Index Terms

AGC, Area Control Error, Integral Controller, Fuzzy Logic Control.

 

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AGC of an Interconnected Power System Using Fuzzy Logic Control

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Performance Analysis of SRM Drives using Soft Computing Technique based Fuzzy Logic Controller

Authors: M.Hari Prabhu, and M.Sathya


Abstract

This project is based on the Performance analysis of  Switched Reluctance Motor (SRM) drives using Z-Source Inverter with the soft computing based Fuzzy logic rule base of control rule reduction with the output scaling factor(SF) Self-Tuning Fuzzy Controller (STFC) mechanism are proposed. Fuzzy logic speed controller for SRM drives can produce smooth torque and improve the system performance. The output SF of the controller can be tuned continuously by a gain updating factor, whose value is derived from fuzzy logic, with the plant error and error change ratio as input variables. The result shows the effective control rule reduction of the proposed methods which can be carried out on a four-phase 8/6 pole SRM are given to show the very good stability and robustness against speed and load variations over a wide range of operating conditions.

 

Index Terms

Fuzzy logic controller, scaling factor (SF), switched reluctance motor (SRM), Z-Source Inverter.

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Performance Analysis of SRM Drives using Soft Computing Technique based Fuzzy Logic Controller

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