Swagat Pati

Teaching-learning based optimization algorithm based fuzzy-PID controller for automatic generation control of multi-area power system

Fuzzy-PID controller is proposed for AGC of multi-area power system.TLBO algorithm is applied to optimize the parameters of fuzzy-PID controller.The superiority of proposed approach over LCOA, GA, PS and SA based PID controller is shown.Robustness analysis is performed under wide changes in system parameters and disturbance. This paper deals with the design of a novel fuzzy proportional-integral-derivative (PID) controller for automatic generation control (AGC) of a two unequal area interconnected thermal system. For the first time teaching-learning based optimization (TLBO) algorithm is applied in this area to obtain the parameters of the proposed fuzzy-PID controller. The design problem is formulated as an optimization problem and TLBO is employed to optimize the parameters of the fuzzy-PID controller. The superiority of proposed approach is demonstrated by comparing the results with some of the recently published approaches such as Lozi map based chaotic optimization algorithm (LCOA), genetic algorithm (GA), pattern search (PS) and simulated algorithm (SA) based PID controller for the same system under study employing the same objective function. It is observed that TLBO optimized fuzzy-PID controller gives better dynamic performance in terms of settling time, overshoot and undershoot in frequency and tie-line power deviation as compared to LCOA, GA, PS and SA based PID controllers. Further, robustness of the system is studied by varying all the system parameters from -50% to +50% in step of 25%. Analysis also reveals that TLBO optimized fuzzy-PID controller gains are quite robust and need not be reset for wide variation in system parameters.

Performance improvement of indirect vector controlled induction generator system with sliding mode controller

In this paper, the transient and steady state performance improvement of an indirect vector controlled cage induction generator is presented. Two different types of controllers, namely P-I and a sliding mode controller are designed and simulated, for an application in wind turbine driven line connected induction generator. It is verified that the proposed sliding mode controller improves the performance of the vector controlled cage induction generator system.

Decoupled control of active and reactive power in a DFIG based wind energy conversion system with conventional P-I controllers

Variable speed wind energy system uses mostly doubly-fed induction generators(DFIGs) for its application which gives better performance, maximum power output etc. Various control scheme is used for both machine-side converter control and grid-side converter control. In this paper stator-flux oriented vector control scheme is used in machine-side converter by which decouple control of active and reactive of DFIG is achieved. Grid voltage oriented vector control is used in grid-side, which maintains the dc-link voltage and improves the power factor at rotror-side. Dynamic modelling of DFIG is described first in this paper. Vector control scheme for both grid-side and machine-side using P-I controller is modeled in Matlab and the results are analysed.

Performance comparison of a SRM drive with conventional PI, fuzzy PD and fuzzy PID controllers

Switched reluctance motor because of its simple construction, robustness and reliability has become superior to other electric machine. This paper presents the speed control of switched reluctance motor (SRM). In this work the performance of the switched reluctance motor is evaluated by subjecting the motor to two different disturbances. First the motor is subjected to a step change in load torque and its performance was evaluated. Again a step change in speed is done to study the system performance. Three different i.e. conventional PI controller, fuzzy PD and fuzzy PID controller are used for the controlled purpose of the switched reluctance motor and their performances are studied and compared in this work. The whole work is done in MATLAB/SIMULINK environment.

Voltage and frequency control of a micro-grid using a fuzzy logic controller based STATCOM equiped with battery energy storage system

It has become now a big challenging task to generate electricity in remote locations without the help of any external energy sources. One of the most effective solution to encounter this problem is the use of self excited induction generator producing electricity even in the absence of external energy source. Though self excited induction generator can act as a good isolated source of electricity, one of its greatest disadvantage is its fluctuating nature of voltage and frequency under varying load condition. Here in this paper we have considered a self excited induction generator along with a doubly fed induction generator with the former connected to the latter by a transmission line to form the proposed micro-grid system. The problems associated with the system are the varying nature of voltage and frequency which can be observed under different loading conditions such as linear load, nonlinear load, and dynamic load. The system also comprises of also a STATCOM with battery energy storage system which acts in order to balance the deviation resulted in the reactive and active power thereby maintaining the voltage and frequency. The controller used in this work is a fuzzy logic controller which carries out the controlling action through the STATCOM. The simulation for the above model is done in MATLAB / SIMULINK.

Fuzzy logic controller based STATCOM for voltage profile improvement in a micro-grid

Microgrids constitute a very essential part in todays power system for fulfilling the increasing power demand but when working under isolated conditions microgrids become very vulnerable due to the fact that normally microgrids have small generation capacities and most of the generation sources are renewable/constant power sources, which reduces the transient as well as voltage stability limits of a microgrid when working under isolated conditions. In this work a single synchronous generator based isolated microgrid system is studied. The microgrid system feeds power to a concentrated time varying load. Fluctuation in load causes variation in the load bus voltage which reduces the stability of the system. A Static Synchronous Compensator (STATCOM) is used to improve the voltage profile of the load bus. Two different controllers: PI and fuzzy logic are used for the control purpose of the STATCOM. The performance of the STATCOM with both the controllers is evaluated with different load conditions: R-L load, nonlinear load and dynamic load. The results are analyzed and compared. The simulation is done in Matlab/Simulink.

Voltage profile improvement of a two generator based micro grid system using STATCOM

Power shortage has become a very serious problem for the power distribution and consumers. Along with it, power demand at remote locations and providing uninterrupted power have created more challenges which have to be dealt with. The most feasible solution for these problems is distributed generation or formation of micro-grids involving renewable energy sources. But micro-grids suffer from voltage fluctuations and power oscillations, which increase the instability of the system. Use of FACTS devices can be effective for improvement of the stability of the micro-grid system. This paper presents a micro-grid system comprising of two diesel generating units using alternators and a load. A STATCOM is connected to the load bus for the voltage profile improvement of the system. Dynamic modeling of the micro-grid system is done and the system is simulated with and without STATCOM. The results are analyzed. The system is simulated using MATLAB/SIMULINK environment.

Sliding mode controller based decoupled control of STATCOM for voltage profile improvement in a micro grid system

Micro grids have become ultimate solution to the energy crisis in the world. But the micro grid are most vulnerable while working in the isolated mode. Because due to the small generation capacity and highly fluctuating loads the voltage profile of the micro grid system deteriorates, which undesirable voltage dips and even causes instability. To get rid of these problems many FACTS devices have been developed which can compensate reactive power of the system rapidly. In this work micro grid system is considered which constitutes of an alternator feeding a concentrated load through a transmission line. A STATCOM is connected at the load bus to improve the voltage profile of the system. The STATCOM is controlled by a control scheme which enables fast and decoupled control of active and reactive power. Sliding mode controllers, which are considered to be fast and robust are designed and implemented for the power control purpose of the STATCOM. The performance of the micro grid is simulated and analyzed with and without STATCOM, and the results are presented. The simulation is done in Matlab/Simulink platform.

Improvement of transient and steady state performance of a scalar controlled induction motor using sliding mode controller

Because of its low maintenance and robustness, induction motors have many applications in the industries. Most of these applications need fast and accurate speed control system. This paper investigates about the basic control process of induction motor i.e. scalar V/F control with a conventional PI controller. Then a sliding mode controller is designed and implemented for the performance improvement of the system. Induction motor is modeled in the synchronous reference frame. The induction motor is supplied through an inverter. The model is carried out by using Matlab/Simulink. The simulation results have been discussed in the paper.

A direct torque controlled cage induction generator using back to back PWM converters for grid connected variable speed wind energy system

A wind energy conversion system (WECS) differs from a conventional power system in a lot of ways. In a conventional power plant, the power generation can be controlled easily, as the fluctuations in active and reactive power are not so frequent. But, the power output of a WECS fluctuates with the wind velocity, which makes it difficult to analyze and control. Various approaches have been developed to enhance the performance of a WECS. A variable-speed wind turbine has two back-to-back PWM converters which consists of a machine-side converter for generator control and a grid-side converter for grid-side power control. In this paper Direct Torque Control scheme has been adopted for generator- side convertor control and Grid voltage oriented Vector control scheme is adopted for controlling the grid- side convertor. In both the schemes PI controllers are used. The whole scheme is simulated in Matlab and the results are interpreted.