Three phase inverter control using DSP controller for dynamic voltage restorer (DVR) application

This paper discusses the control technique improvement of a three-phase inverter using directquadrature- zero (d-q-0) controller based on DSP TMS320F2812 for dynamic voltage restorer (DVR) applications. The output of the inverter is then connected to a voltage grid via a second order filter and injection transformer. The control algorithms are developed using TMS320F 2812 DSP. The proposed technique achieves voltage regulation with low total harmonics distortion (THD) for both voltage and current. This paper also highlights a series of discussion, analysis and studies performed on the proposed control technique, including L-C filter design issue and the concept of DVR in the distribution system. An analysis and experimental results validate the effectiveness of the DSP controller in mitigating voltage sags and harmonics issues in the distribution syste

Performance of Modification of a Three Phase Dynamic Voltage Restorer (DVR) for Voltage Quality Improvement in Electrical Distribution System

There is growing concern over power quality of ac supply systems. Power quality can be defined as the ability of utilities to provide electric power without interruption. Various power quality problems can be categorized as voltage sags, swells, harmonics, transients and unbalance are considered are the most common power quality problems in electrical distribution systems (Elandy etl., 2006). These types of disturbances can cause fails in the equipments, raising the possibility of an energy interruption.Voltage swells can be defined as a short duration increase in rms of main source with an increase in voltage ranging from 1.1 p.u up to 1.8 p.u. of nominal voltage source. There are various solutions to these problem

Performance Of Multilevel Inverters For Harmonic Reduction In Dynamic Voltage Restorer Application

Multilevel inverters are known for their intial usage in high-voltage and high-power applications.This thesis presents the analysis and design of the Three-Phase Cascaded H-Bridge Multilevel Inverters (CHB-MLI) for three and five levels based on Newton-Raphson technique for harmonic reduction in Dynamic Voltage Restorer (DVR) application.The performance of the inverter outputs to reduce harmonics is crucial for DVR applications.Two DC sources were applied for two types of CHB-MLI.These types of inverters used Newton-Raphson method as their controllers.The main aim of this thesis is to design, model,construct,and conduct laboratory testing upon CHB-MLI of a three and five levels prototype for DVR application.The design of suitable multilevel inverters is very important for DVR purposes,so that the AC output voltage waveforms of the inverters have low content of harmonics during energy conversion process from DC to AC of the proposed inverters.The Digital Signal Processing (DSP) TMS320F2812 was used as a tool in order to create the coding based on the Newton-Raphson technique controller.The coding was developed,and then stored into the Digital Signal Processing (DSP) TMS320F2812 for output processing of the waveform of the inverters.The proposed controller using Newton-Raphson technique was applied to both three and five level of CHB-MLI.The optimization of this system has managed to reduce the harmonic contents of the inverters output.The performance of the developed prototype was tested using source codes of the programming for optimization technique.The experimental results of the developed prototype for both three and five levels were monitored and analysed.In addition,the performance of the proposed system was compared between simulation and experimental results for the optimization technique.The simulation and experimental results had shown the effectiveness of the proposed system in reducing harmonic.The waveforms in term of current and voltage were smooth and contain low contents of harmonic.Types of waveforms for five level of CHB-MLI which were more suitable to be used in the DVR applications

Improvement of Power Quality in Distribution System using DVR

Today PQ(Power quality) is major issue in production/power industries and distribution network. As there are numerous PQ problems but the sag and swell are the important one. We have various CPD’s (custom power devices) used for linear and non-linear loads that can eliminate/mitigate the voltage sag and swell and finally restore’s the system to the pre-fault condition. This paper presents improvement of voltage using DVR for balanced /unbalanced voltage sags/ swells and therefore MATLAB/SIMULINK based simulation Results proved the efficiency of DVR to mitigate/eliminate voltage sags /swells

Hardware integration of ultracapacitor based energy storage to provide grid support and to improve power quality of the distribution grid

Grid integration of distributed energy resources (DERs) is increasing rapidly. Integration of various types of energy storage technologies like batteries, ultracapacitors (UCAPs), superconducting magnets and flywheels to support intermittent DERs, such as solar and wind, in order to improve their reliability is becoming necessary. Of all the energy storage technologies UCAPs have low energy density, high power density and fast charge/discharge characteristics. They also have more charge/discharge cycles and higher terminal voltage per module when compared to batteries. All these characteristics make UCAPs ideal choice for providing support to events on the distribution grid which require high power for short spans of time. UCAPs have traditionally been limited to regenerative braking and wind power smoothing applications. The major contribution of this dissertation is in integrating UCAPs for a broader range of applications like active/reactive power support, renewable intermittency smoothing, voltage sag/swell compensation and power quality conditioning to the distribution grid. Renewable intermittency smoothing is an application which requires bi-directional transfer of power from the grid to the UCAPs and vice-versa by charging and discharging the UCAPs. This application requires high active power support in the 10s-3min time scale which can be achieved by integrating UCAPs through a shunt active power filter (APF) which can also be used to provide active/reactive power support. Temporary voltage sag/swell compensation is another application which requires high active power support in the 3s-1min time scale which can be provided integrating UCAPs into the grid through series dynamic voltage restorer (DVR). All the above functionalities can also be provided by integrating the UCAPs into a power conditioner topology. --Abstract, page iv

Unified Power Quality Conditioner for Grid Integration of Wind Generators

A Unified Power Quality Conditioner (UPQC) is relatively a new member of the custom power device family. It is a comprehensive custom power device, with integrated shunt and series active filters. The cost of the device, which is higher than other custom power/FACTS devices, because of twin inverter structure and control complexity, will have to be justified by exploring new areas of application where the cost of saving power quality events outweighs the initial cost of installation. Distributed generation (such as wind generation) is one field where the UPQC can find its potential application. There has been a considerable increase in the power generation from wind farms. This has created the necessity for wind farms connectivity with the grid during power system faults, voltage sags and frequency variations. The application of active filters/custom power devices in the field of wind generation to provide reactive power compensation, additional fault ride through capability and to maintain Power Quality (PQ) at the point of common coupling is gaining popularity. Wind generation like other forms of distributed generation often relies on power electronics technology for flexible interconnection to the power grid. The application of power electronics in wind generation has resulted in improved power quality and increased energy capture. The rapid development in power electronics, which has resulted in high kVA rating of the devices and low price per kVA, encourages the application of such devices at distribution level. This work focuses on development of a laboratory prototype of a UPQC, and investigation of its application for the flexible grid integration of fixed and variable speed wind generators through dynamic simulation studies. A DSP based fully digital controller and interfacing hardware has been developed for a 24 kVA (12 kVA-shunt compensator and 12 kVA-series compensator) laboratory prototype of UPQC. The modular control approach facilitates the operation of the device either as individual series or shunt compensator or as a UPQC. Different laboratory tests have been carried out to demonstrate the effectiveness of developed control schemes.A simulation-based analysis is carried out to investigate the suitability of application of a UPQC to achieve Irish grid code compliance of a 2 MW Fixed Speed Induction Generator (FSIG). The rating requirement of the UPQC for the wind generation application has been investigated. A general principle is proposed to choose the practical and economical rating of the UPQC for this type of application. A concept of UPQC integrated Wind Generator (UPQC-WG) has been proposed. The UPQC-WG is a doubly fed induction machine with converters integrated in the stator and rotor circuits and is capable of adjustable speed operation. The operation of UPQC-WG under sub and super-synchronous speed range has been demonstrated. The Irish grid code compliance of the same has been demonstrated with a detailed dynamic simulation

Unified Power Quality Conditioner: protection and performance enhancement

The proliferation of power electronics-based equipment has produced a significant impact on the quality of electric power supply. Nowadays, much of the equipment is based on power electronic devices, often leading to problems of power quality. At the same time this equipment is typically equipped with microprocessor-based controllers which are quite sensitive to deviations from the ideal sinusoidal line voltage. Conventional power quality mitigation equipment is proving to be inadequate for an increasing number of applications, and this fact has attracted the attention of power engineers to develop dynamic and adjustable solutions to power quality problems. One modern and very promising solution that deals with both load current and supply voltage imperfections is the Unified Power Quality Conditioner (UPQC). This thesis investigates the development of UPQC protection scheme and control algorithms for enhanced performance. This work is carried out on a 12 kVA prototype UPQC. In order to protect the series inverter of the UPQC from overvoltage and overcurrent during short circuits on the load side of the UPQC, the secondary of the series transformer has to be short-circuited in a reasonably short time (microseconds). A hardware-based UPQC protection scheme against the load side short circuits is derived and its implementation and effectiveness is investigated. The main protection element is a crowbar connected across the secondary of the series transformer and consisting of a pair of antiparallel connected thyristors, which is governed by a very simple Zener diode based control circuit. Also, the software-based UPQC protection approach is investigated, the implementation of which does not require additional hardware

Digital signal processing for segmented HPGe detectors preprocessingalgorithms and pulse shape analysis

MINIBALL is an versatile spectrometer consisting of 24 longitudinally six-fold segmented HPGe detectors, build for the efficient detection of rare γ decays in nuclear reactions of radioactive ion beams. MINIBALL was the first spectrometer equipped with digital electronics. Pulse shape analysis algorithms to determine the interaction position of γ -rays were implemented on a Digital Signal Processor and validated in an experiment using a collimated γ -ray source. Emphasis was placed on the properties of the different digital signal processing algorithms, the consequences for the implementation and the applicability for position determination. The next generation of γ -ray spectrometers will consist of highly segmented HPGe detectors equipped with digital electronics, resulting in a more than ten-fold increase in complexity compared to current spectrometers. To enable the construction of a γ -ray tracking spectrometer, new and powerful digital electronics will be developed. Preprocessing algorithms, giving the γ -ray energy and generating event triggers, were implemented on a VME module equipped with fast A/D converters and tested with different detectors and sources. Emphasis was placed on the detailed simulation and understanding of the algorithms as well as the influence of electronics and detector onto the energy resolution