The Response Of PI Controller For Islanding And Non-Islanding Conditions

It is observed that the power factor is maintained closer to unity when the input voltage is reduced from 230V to 110Vrms. Figure 11 (a) and (b) shows the power factor correction of controller for various load condition such as 20% (60W) and 75% (230W). The power factor for the system is found to be 0.84 for light load condition and 0.99 for full load condition. The THD of input current at full load with predominant third and fifth harmonic components are shown in Figure 12(a) and (b).Third harmonics is found to be 4.8% and fifth harmonic component is 4.9% which are well within IEC 61000-3-2 standard during wide range of load variations. The variation in power factor with load is shown graphically in Figure 13(a). It can be inferred from the graph that improved resettable control operates at high power factor for all load condition whereas the conventional PI control has poor power factor under light load conditions. Figure 13(b) shows the comparison between the efficiency of the converter for varying load conditions with the conventional control method and the resettable integrator control. The converter’s efficiency is maintained at 92% for light load conditions and 96% for fully loaded condition with integrator control technique. Thus the improved resettable integrator controller provides a very simple and reliable solution for power factor correction and

Switching power converters offer an easy way to regulate both the frequency and magnitude of the voltage and current applied to a motor shown in fig(1). As a result much higher efficiency and performance can be achieved by these motor drives with less generated noises[3].

reducing the output ripple current and the total harmonic distortion of the output current, increasing the power density of system, and reducing the current stress and thermal stress of power devices. Besides, it can solve the problem of zero sequence circulation current (ZSCC) in interleaved inverter system by the circuit structure, and it also has the advantages of no shoot-through problem, no reverse recovery of the body diode, and three-level output. The interleaved inverter circuits share two power-frequency switches, which are resized for each specific application, and it is easier to extend the system by improving current capability of the two switches. The working principle of this system is introduced in detail and a 2 kW experimental prototype has been established and tested. Test results verify the principle and

In [34] authors has designed a new types of transformer less three-phase three-level NPC based power converter which performance has been analyzed in 2.64–4.16 kV DC, 5.1–12.8 kW. It’s performance like DC link voltage, efficiency & THD profile was acceptable. The authors assumed that this converter will be suitable for 15kV grid voltage. Converter switching circuit has been designed in SiC (Silicon Carbide) IGBT & Diodes as shown in Fig.18. So, this converter can be re-designed for medium or high voltage with SiC

Identify and analysis of technical features and design criteria of the possible re-active power compensation (RPC) equipments.

At present there are several reduction or mitigation methods in use to reduce the distortion of the voltage and current from non-linear distribution loads such as variable frequency drives (VFDs). Description of each method with relative advantages and disadvantages are as follows.

 The basic objective of this paper is to extract maximum power and to maintain power quality to a satisfactory level from the varying condition the Photovoltaic array with different solar irradiation.

The objective of the proposed internship can be divided into the following sub-objectives – 1) develop a control strategy with variable operating switching frequency to dynamically control current ripple and reduce system losses, and 2) develop a current control strategy to improve dynamic response for the two level inverter fed PMSM drive; while taking into account the effect of different operating regions and drive design parameters. More specifically the following tasks will be accomplished for each sub-objective:

Abstract—Grid-connected inverters (GCI) are widely used to feed power from renewable energy distributed generators into smarter grids. Repetitive control (RC) enables such inverters to inject high quality fundamental-frequency sinusoidal currents into the grid. However, digital RC which can get approximately no tracking error of any periodic signal in steady-state whose period is known, cannot exactly track or reject periodic signal of frequency variations. Thus digital RC would lead to a significant power quality degradation of GCIs when grid frequency varies and causes periodic signal with non-integer periods. In this research paper a repetitive control scheme capable of frequency adaptation (FARC) at a predefined sampling rate is proposed to deal with all types of periodic signal of variable frequency. A fractional delay filter which is based on Lagrange interpolation is used to estimate the fractional period terms in RC. This proposed FARC controller offers the fast during process modification of fractional delay and fast revise of filter parameters, and then provides GCIs with a simple but very accurate existent time frequency adaptive control

This thesis deals with the design and analysis of control system structures for electric drives equipped with permanent magnet synchronous machines (PMSM) in automotive application.With the increasing popularity of multi-level inverters, the room for improvement of the performance of voltage source inverters has continuously been tested for various applications. The rapid development of high switching frequency power electronics in the past decade leads towards wider application of voltage source inverters in AC power generation. Therefore, this prompts the need for a modulation technique with less total harmonic distortion, fewer switching losses, and wider linear modulation range.The present thesis highlights the comparison of the conventional two-level inverter and the three-level diode clamped inverters for the application in automotive industry.

A harmonic source can be any type of equipment where a distorted-wave current flows through an application with a sine-wave commercial-power-supply voltage. The converter circuit (rectifying circuit) of an inverter is no exception. These do not usually upset the end-user electronic equipment as much as they overload neutral conductors and transformers and, in general, cause additional losses and reduced power factor [1–5]. Large industrial converters and variable speed drives on the other hand are capable of generating significant levels of distortion at the point of common coupling (PCC),

There are numerous methods which are as follows like (SPWM) First Sinusoidal Pulse Width Modulation, (MCPWM)Second, Multi-Carrier Pulse Width Modulation and (SHE-PWM) and Selective Harmonic Elimination Pulse Width Modulation which are implemented for harmonic elimination specially in multilevel inverter. (MCPWM)Multi-Carrier Pulse Width Modulation strategies are widely used, because they can be easily implemented to low voltage modules. Normally MCPWM can be classified and categorized as Level Shifted PWM (LS-PWM) and Phase Shifted PWM (PS-PWM) methods. (LS-PWM) Level Shifted PWM are characterized into three which are Firstly ,Phase Disposition Technique (PD), secondly ,Phase Opposition Disposition Technique (POD) thirdly Alternative Phase Opposition Disposition Technique (APOD) [45] [46] [47].

In a typical microgrid, small-scale generators such as wind, photovoltaic (PV), fuel cells, and small-scale gas turbines are installed proximity to the load side, and inverters are used as interface devices. Inverters play an important role in

This project is aim to study the principle of pwm, single-phase inverter, three-phase inverter which leading to design a three-phase inverter(DC-AC) by using the mbed to control switch. This inverter will be intended to drive an induction motor which may need to drive. The work will involve simulation study of PWM generators, induction motors and device selected from.

The modulation methods used in multilevel inverters can be classified according to the switching frequency was discussed in Rodriguez et al (2002), Celanovic and Boroyevic (2001) and Rodriguez et al (2001). Modulation techniques that work with high switching frequencies have many commutations for the power semiconductors in a cycle of the fundamental output voltage. Multilevel inverters generate sinusoidal voltages from discrete voltage levels, and Pulse Width-Modulation (PWM) strategies accomplish this task of generating sinusoids of variable voltages and frequencies. Several techniques for the implementation of PWM for multilevel inverters have been developed.