Design of Optimal PI Controllers for Doubly Fed Induction Generators Driven by Wind Turbines using Particle Swarm Optimization

When subjected to transient disturbances in the power grid, the variable frequency converter (VFC) is the most sensitive part in the variable-speed wind turbine generator system (WTGS) equipped with a doubly fed induction generator (DFIG). The VFC is normally controlled by a set of PI controllers. Tuning these PI controllers is a tedious work and it is difficult to tune the PI gains optimally due to the nonlinearity and the high complexity of the system. This paper presents an approach to use the particle swarm optimization algorithm to design the optimal PI controllers for the rotor-side converter of the DFIG. A new time-domain fitness function is defined to measure the performance of the controllers. Simulation results show that the proposed design approach is efficient to find the optimal parameters of the PI controllers and therefore improves the transient performance of the WTGS over a wide range of operating conditions

Optimal design of cascaded control scheme for PV system using BFO algorithm

In this paper presents Bacteria Foraging Optimization (BFO) algorithm based approach to find the optimum design values for the Proportional-Integral (PI) Controllers in cascaded structure is presented. Tuning the values of four PI controllers is very complex when the system is difficult to express in terms of mathematical model due to system nonlinearity. Response surface methodology (RSM) is used to formulate a mathematical design which is required to apply optimization algorithm. To examine the performance of BFO algorithm in obtaining optimum values of multiple PI controllers, a grid connected Photovoltaic (PV) system is chosen. Transient performance of the PI controller with optimum design values is evaluated under grid fault conditions. The system is simulated using PSCAD/EMTDC. Simulation results have shown the validity of the optimal design values obtained from RSM-BFO approach under different disturbances and system parameter variations

Control of Multiple Remote Servers for Quality-Fair Delivery of Multimedia Contents

This paper proposes a control scheme for the quality-fair delivery of several encoded video streams to mobile users sharing a common wireless resource. Video quality fairness, as well as similar delivery delays are targeted among streams. The proposed controller is implemented within some aggregator located near the bottleneck of the network. The transmission rate among streams is adapted based on the quality of the already encoded and buffered packets in the aggregator. Encoding rate targets are evaluated by the aggregator and fed back to each remote video server (fully centralized solution), or directly evaluated by each server in a distributed way (partially distributed solution). Each encoding rate target is adjusted for each stream independently based on the corresponding buffer level or buffering delay in the aggregator. Communication delays between the servers and the aggregator are taken into account. The transmission and encoding rate control problems are studied with a control-theoretic perspective. The system is described with a multi-input multi-output model. Proportional Integral (PI) controllers are used to adjust the video quality and control the aggregator buffer levels. The system equilibrium and stability properties are studied. This provides guidelines for choosing the parameters of the PI controllers. Experimental results show the convergence of the proposed control system and demonstrate the improvement in video quality fairness compared to a classical transmission rate fair streaming solution and to a utility max-min fair approach

Fuzzy PI Controllers Performance on Boost Converter

Electric voltage of about 220 volts is required to supply the home appliance in Indonesia, such as for lighting lamps. When there is no 220 volts power supply, while the available voltage source is equal to the battery voltage of about 1.5 to 12 volts, it requires the voltage converter to convert a low voltage 220 volts Become. By using a transformer, it is easy to rise the AC voltage. Meanwhile for DC voltage, the transformer can not be used to raise it, Because The changing magnetic field do not occur then the output of transformer voltage is not higher but the transformer Become hot Because of DC voltage. To raise the DC voltage, DC to DC converter is needed, such as Boost Converter. Boost Converter works based on the changing current that flows through an inductor. This current change will Affect the inductor voltage change. The output voltage of boost converter has a unique comparison to the input voltage duty cycle. By adjusting the amount of the voltage duty cycle, the output voltage will be easy to control. In this paper, we presented a prototype of 12 to 220 V DC-DC boost converter, using fuzzy-PI intervention that being embedded on ATmega168 AVR microcontroller. The controller can maintain a fixed output voltage by regulating the input duty cycle. From the test results, is obtained an efficiency of 75% at 15 watts whereas percentage of error of about less than 3%.DOI:http://dx.doi.org/10.11591/ijece.v3i2.226

PI Controller Design for DC Motor Using Different Power Electronic Converters

In this paper, the design of a PI controller of a DC motor closed-loop torque control system is presented. The controllers are designed using small signal models and then verified using large signal simulation. A step by step design procedure is carried out to determine the response of each loop and appropriate parameters of the PI controllers are shown throughout this study assisted by Bode Plot and pole zero map techniques. In this paper also, there is comparison made when using different power electronic converters between 3-phase controlled rectifier and 4-quadrant switch mode DC-DC converter. It is highly demanded to design the PI controllers that will result in high performance in terms of high speed of response, low steady state error and high degree of stability. In this paper, simulation studies are included to show that the PI controllers designed could control the torque as desired and achieve satisfactory performance. The analysis of performance of torque and speed is compared with the desired (reference) values based on MATLAB/SIMULINK simulation