ADVANCED INVERTER CONTROL FOR UNINTERRUPTIBLE POWER SUPPLIES AND GRID-CONNECTED RENEWABLE ENERGY APPLICATIONS By Shuai Jiang Michigan State University

ADVANCED INVERTER CONTROL FOR UNINTERRUPTIBLE POWER

SUPPLIES AND GRID-CONNECTED RENEWABLE ENERGY

APPLICATIONS

By

Shuai Jiang

A DISSERTATION

Submitted to

Michigan State University

in partial fulfillment of the requirements

for the degree of

Electrical Engineering – Doctor of Philosophy

2013

ABSTRACT
ADVANCED INVERTER CONTROL FOR UNINTERRUPTIBLE POWER SUPPLIES AND GRID-CONNECTED RENEWABLE ENERGY APPLICATIONS By Shuai Jiang
The advancement of digital signal processors (DSPs) and programmable logic devices in modern power electronics systems offer great control flexibility and capability, providing attractive features particularly for applications in which complex control tasks are involved. This dissertation investigates some DSP based advanced control algorithms for pulse-width modulation (PWM) inverter applications, in particular, voltage regulated inverters connected with AC loads and current regulated inverters connected with utility grids. Uninterruptible power supply (UPS) is a typical example of voltage regulated inverter applications. It is widely used to supply high quality, continuous and disturbance-free AC power to critical loads such as medical equipments, computers and communication systems. A good UPS system requires not only excellent steady state performances in terms of voltage regulation and total harmonic distortions (THD) regardless of unknown load disturbances but also a fast transient response during load step change. In this dissertation, a three-phase four-wire AC-DC-AC double conversion UPS system is first studied. Multi-loop control strategies are designed to regulate the system input currents, DC voltages, and output voltages. Next, study will deep dive into a DC-AC three-phase UPS inverter. A high performance repetitive controller (RC) for the voltage regulated three-phase inverter is proposed. The proposed control algorithm can eliminate all the periodic distortions and guarantees a high quality sinusoidal output voltage under unknown and severely distorted loads. A novel 4th-order linear phase infinite-impulse-response (IIR) filter is first used in the RC such that harmonic distortions up to the 19th order are rejected. In order to achieve fast response during step load transient while still maintaining the low THD feature, a modified synchronousframe approach with significantly reduced delay is later proposed and investigated. Grid-connected inverters utilizing renewable energy sources (e.g., photovoltaic, wind, fuel cell, etc.) are growing rapidly in recent years along with the constantly growing global demand for electricity. A grid-connected inverter injects a synchronously regulated sinusoidal current to the utility grid with required low THD and high power factor. Using an LCL filter in such a system has been recognized as a small size low cost solution due to its -60dB/dec high frequency attenuation. In this dissertation, a high-resonance-frequency LCL filter with minimal size and cost requirement is designed. A proportional plus repetitive control hybrid strategy is then proposed to achieve very low THD current regulation and high power factor.
 FULL THESIS LINK:
http://etd.lib.msu.edu/islandora/object/etd%3A2193/datastream/OBJ/view

POWER CONVERTER SYSTEMS FOR HVDC TRANSMISSION INTEGRATED WITH WIND FARM Yeungnam University Department of Electrical Engineering AUTHOR Thanh Hai Nguyen

Ph.D. Thesis
POWER CONVERTER SYSTEMS FOR HVDC TRANSMISSION INTEGRATED WITH WIND FARM
 Advisor: Professor Dong-Choon Lee Presented as Ph.D. Thesis 2013 June Graduate School of Yeungnam University Department of Electrical Engineering Control and Electric Machinery ∙ Power Conversion Major
Author :Thanh Hai Nguyen

Abstract In this thesis, a novel power converter system for high-voltage direct current (HVDC) transmission integrating the offshore wind farm (WF) into the grid is proposed, in which a hybrid of a twelve-pulse diode rectifier (12P-DR) and a voltage-source converter (VSC) is employed. For this topology, the 12P-DR is capable of delivering a part of wind farm power, the rest of which is absorbed by the wind farm VSC (WFVSC) since the WFVSC is controlled and operated as a voltage source of a constant frequency. Also, the current at the PCC becomes almost sinusoidal since the WFVSC functions as an active power filter for the 11th- and 13th-order harmonic current components. By virtue of the diode rectifier, the voltage rating of the diode rectifier and the VSC is reduced by configuring them in series connection. Then, the cost and power loss of HVDC converters is reduced compared with the case of the conventional fully-rated VSC, whereas the performance is kept almost the same. By a simple VSC with two levels, the efficiency of the proposed HVDC converter is about 99.07% high, compared with 98.4% in the fully-rated VSC system, and the cost of power semiconductor devices including the gate drivers in the HVDC converter system is about 53.47% compared with that of in the VSC-based HVDC links. In addition, to improve the performance and the efficiency of the power converter system for HVDC links, the modular multilevel converter (MMC) is utilized instead of the simple 2-level VSC, in which the efficiency of the proposed HVDC system is about 99.27% compared with 99.0% and 98.4% of the HVDC transmission systems based on the fully-rated capacity of the MMC and the neutral-point clamped (NPC) multilevel converter, respectively. For integrating the HVDC transmission system with the distorted and unbalanced voltage of the network, a novel control scheme for the grid-side converter of the HVDC transmission systems based on a composite observer is proposed to mitigate the grid current distortions due to unbalanced and distorted grid voltage conditions for the gridconnected PWM converter. The composite observers can extract the fundamental and harmonic components of the grid voltages and currents precisely without any magnitude reduction or phase delay. Then, the positive- and negative-sequence components are separated from the fundamental components by all-pass filters. The grid current components are regulated by a multi-loop harmonic current controller, in which the positive-sequence component is regulated by PI (proportional-integral) controllers and the negative-sequence and harmonic components are regulated by PR controllers. This approach allows the unbalanced and distorted components in the grid current to be eliminated from the system. For the wind farm operation, a control strategy to smooth the output power of the wind farm before delivering to the grid is also proposed, in which the inertial effect of the wind turbines and coordinated operation of individual wind turbines (WT) are utilized. A two-level control scheme is applied to control the wind farm, which consists of a high-level control for the wind farm and low-level controls for individual WTs. The power references of the wind farm and each wind turbine generator are produced by the high-level controller, whereas the individual WTs are controlled to produce the power as their commands by the low-level controllers. With the control scheme, the output power of the WF is smoothened, even though the output powers of individual WTs are fluctuated. For this control strategy, when the reference power is lower than the available power, some of individual wind turbines are operated in the kinetic energy charge operation by increasing the turbine speeds. Then, some of individual wind turbines release the power by reducing the turbine speed, when the power command is higher than the available power. The PSCAD/EMTDC simulation results for a 500-MW HVDC transmission system integrating the wind farm into the grid have been shown to verify the validity of the proposed scheme. Also, the experimental tests have been carried out for the laboratoryscaled system of the HVDC link and wind turbine system.

TÓPICOS SOBRE DIMENSIONAMENTO DE TRANSFORMADORES PARA SISTEMAS DE DISTRIBUIÇÃO

 LINK
http://www.leonardo-energy.org.br/biblioteca-virtual/dimensionamento-de-transformadores-para-sistemas-de-distribuicao/

Convertisseurs et électronique de puissance

LINK
http://issuu.com/adosani.1989/docs/convertisseurs_et___lectronique_de_/1

Simulación de circuitos electrónIcos con PSPICE PROFESOR JUAN AGUILAR

Seminario de simulación de circuitos de electrónica de potencia con pspice realizado como introducción a la asignatura de Electrónica de Potencia de Grado en Ingeniería Electrónica Industrial en la Escuela Politécncia Superior de la Universidad de Jaén
LINK
http://issuu.com/jaguilarpena/docs/seminario/1