Reliable Power Electronics for Wind Turbines

Chapter 31 - Power Electronics Applications in Smart Grid

A key issue for power electronic converters is the ability to tackle periodic signals in electrical power processing to precisely and flexibly convert and regulate electrical power. This book provides complete analysis and synthesis methods for periodic control systems. It covers the control, compensation, and filtering of periodic signals in power electronic power processing and proposes a unified framework for housing periodic control schemes for power converters, providing a general proportional-integral-derivative control solution to periodic signal compensation in extensive engineering applications - a perfect periodic control solution for power electronic conversion. It provides number of demonstrative practical examples of the application of periodic control to: standalone constant-voltage-constant-frequency (CVCF) singlephase Pulse Width Modulation (PWM) inverters; standalone CVCF singlephase High Frequency Link (HFL) inverters; standalone CVCF three-phase PWM inverters; grid-connected single-phase inverters; grid-connected singlephase Cycloconverter type HFL rectifiers; grid-connected three-phase PWM inverters; programmable AC power sources; shunt active power filters; and UPS systems. Periodic Control of Power Electronic Converters is of key importance for researchers and engineers in the field of power electronic converter systems and their applications, for control specialists exploring new applications of control theory in power electronics, and for advanced university students in these fields.

Power electronics, a pivotal field orchestrating electrical energy flow in the modern world, deals with efficient conversion, control, and management of electrical power across diverse applications. While its scope encompasses circuits for energy conversion, its challenges include transporting electrical energy over extended distances. Focusing on electrical‐to‐electrical conversions, the goal is minimal loss for delivering maximum power. The article explores the intricacies of power electronics, presenting key equations, and concepts. The current global power electronics market witnesses growth, driven by demand for energy‐efficient technologies, renewables integration, and the rise of electric vehicles. Future trends indicate continued growth, driven by renewable energy systems, and electric vehicles. Wide bandgap semiconductors, play a crucial role, with ultra‐wide bandgap semiconductors like diamond emerging as potential disruptors. A comparative analysis of semiconductor properties reveals diamond's unique attributes. Despite its challenges, diamond shows promise for power electronic applications, with ongoing research on components like Schottky diodes. Thermal considerations, substrate limitations, and dislocation challenges are discussed, emphasizing the need for advancements to harness the full potential of diamond in power electronics. Finally, some inputs about the importance of overcoming these challenges for the successful integration of diamond in power electronic systems are given.

Power electronic systems have become a key component in the efficient generation, distribution, storage, and use of energy. This increasingly places power electronic systems in harsh environments under elevated stress conditions where, in many cases, their reliable operation is now mission critical. The semiconductor material conventionally used, silicon, possesses limited capability for high temperature applications due to its small bandgap. Power electronic components based on wide bandgap (WBG) semiconductors, such as SiC and GaN, can be operated reliably at higher temperatures. Furthermore, WBG devices have higher breakdown voltages and switching frequencies, rendering them more ideal switches and rectifiers for highefficiency as well as low-volume and low-weight systems. Yet, new packaging concepts are required to make use of the high temperature capability of power electronic systems based on WBG semiconductor devices. In this paper, a summary of the progress in the development and commercialization of wide bandgap power components and power electronic systems is given. The properties of SiC and GaN components are compared to those based on silicon. The shortcomings of conventional power electronic packaging technologies are analyzed, and alternatives introduced and compared. An overview of research is given on Transient Liquid Phase Sintering (TLPS), a promising interconnect technology for the manufacturing of WBG and high temperature power electronic systems. TLPS is a liquid-assisted sintering process during which a low melting temperature constituent melts, surrounds, and diffuses in a high melting temperature constituent. Intermetallic compounds with high melting temperatures are formed by liquid-solid diffusion. Interconnect systems can be processed at low temperatures but are capable of operating at the high melting temperatures of the intermetallic compound. Different process approaches are contrasted and material systems compared. Latest results of research on paste-based low temperature TLPS are presented. The pastes assessed are based on the Cu-Sn and Ni-Sn material systems. It is shown that joints formed by TLPS remain strong up to 600°C and exhibit softening temperatures far higher than conventional interconnect technologies. They show minimum creep and possess very limited voiding. The process does not require an inert or reducing atmosphere or vacuum and is compatible with standard reflow soldering equipment. It shows good wettability to common metallizations such as Cu, Ni, Ag, and ENIG. This attach technology shows the potential to enable reliable operation of wide bandgap power electronic systems under high stress conditions.

As the applications of power electronic converters increase across multiple domains, so do the associated challenges. With multilevel inverters (MLIs) being one of the key technologies used in renewable systems and electrification, their reliability and fault ride-through capabilities are highly desirable. While using a large number of semiconductor components that are the leading cause of failures in power electronics systems, fault tolerance against switch open-circuit faults is necessary, especially in remote applications with substantial maintenance penalties or safety-critical operation. In this paper, a fault-tolerant asymmetric reduced device count multilevel inverter topology producing an 11-level output under healthy conditions and capable of operating after open-circuit fault in any switch is presented. Nearest-level control (NLC) based Pulse width modulation is implemented and is updated post-fault to continue operation at an acceptable power quality. Reliability analysis of the structure is carried out to assess the benefits of fault tolerance. The topology is compared with various fault-tolerant topologies discussed in the recent literature. Moreover, an artificial intelligence (AI)-based fault detection method is proposed as a machine learning classification problem using decision trees. The fault detection method is successful in detecting fault location with low computational requirements and desirable accuracy.

Microgrids are multi-use, localized power generation systems that integrate different assets. These microgrids use renewable and sustainable energy sources such as solar panels, wind turbines, battery storage, and conventional sources such as gas or diesel generation. This paper defines the architecture of solar power systems and briefly introduces DC-AC converters, highlighting their role as power electronics in solar PV systems. The report describes several classes of converters, such as single-phase half-bridge converters, single-phase full-bridge converters, and three-phase converters. The basics of pulse width modulation (PWM) and carrier-based and non-carrier-based modulation techniques are explained. PWM is often used in converters that act as solar charge controllers. The Simulink MATLAB toolkit is also used to perform a complete simulation and implement a three-phase PWM converter.

Batteries in a fuel cell power system are essential to provide the additional load demands during the sharp load transients. This necessitates a power electronics system, which would control the energy flow between the fuel cell stack, the battery and the load during the transient and in the steady-state. In this paper, a cost-effective and efficient power electronic system is proposed for a fuel cell based hybrid power system based on a distributed power electronics topology. The system includes a hierarchical controlling architecture, in which the master control optimizes the control parameters of the individual subsystem controls, which in turn optimizes the performance and efficiency of the overall system while nullifying the effects of load transients on the fuel cell stack subsystem. The power electronics system concept is further experimentally validated using a four module bidirectional DC-DC converter with Nexa PEM stack.

In this paper we will present a method to facilitate bachelor students with educational laboratory setups which they can use to build fully operational mechatronic and power electronic systems in the spirit of the internet of things. First we will examine all required components and their position in the overall system. It will be demonstrated that both analog and digital control can be applied to the same power electronics board and that this system can be controlled via a web-server. Starting with the internet connection, a Single Board Computer [SBC] will be able to connect to a web-server running a server-side script for communication with the outside world. The user has access to this web-server and can set parameters. The SBC can control multiple micro-controllers via I2C or USB connections. A micro-controller is then reading signals and giving control signals to a high speed analog control circuitry which in turn can regulate the power electronics. The power electronics regulates the electric motor or actuator, driving the actual applications. The main focus of this paper is on the development of a general power electronics board that facilitates multiple purposes. Several aspects of energy conversion have to be taken into consideration and therefore, the board is made general in such a way, that it can serve as a platform to teach students the variety of DC-DC and DC-AC converters that form the energy conversion backbone in the future IoT.

Modeling and Verification of Dependable Electronic Power System Architecture

The electronic power system can be viewed as a system composed of a set of concurrently interacting subsystems to generate, transmit, and distribute electric power. The complex interaction among sub-systems makes the design of electronic power system complicated. Furthermore, in order to guarantee the safe generation and distribution of electronic power, the fault tolerant mechanisms are incorporated in the system design to satisfy high reliability requirements. As a result, the incorporation makes the design of such system more complicated. We propose a dependable electronic power system architecture, which can provide a generic framework to guide the development of electronic power system to ease the development complexity. In order to provide common idioms and patterns to the system *designers, we formally model the electronic power system architecture by using the PVS formal language. Based on the PVS model of this system architecture, we formally verify the fault tolerant properties of the system architecture by using the PVS theorem prover, which can guarantee that the system architecture can satisfy high reliability requirements. KeywordsSystem Architecture; PVS System; Fault Tolerance; Formal Modeling; Formal Verification.

This paper proposes a novel machine parameter independent control algorithm that enables wind turbines to quickly and effectively extract maximum power from the wind turbine under changing atmospheric conditions. The energy captured by a wind turbine varies due to variations in wind velocity, air density (influenced by temperature and humidity), turbine aerodynamics, and generator dynamics. Without power electronics and power extraction control techniques, wind systems have low power extraction efficiency. Given that the power from the wind turbine is dependent on generator rotor speed, the proposed algorithm indirectly uses the tip speed ratio (TSR) to assist in the maximum power point search (MPPS). The slope (or indirect TSR) assisted MPPS provides historic system state information and preempts misguided control decisions due to deceptive power readings caused by atmospheric changes. In this paper, the wind energy system, algorithm design framework, performance, and real-time wind speed data is presented.

HVDC is in many respects the ultimate power electronics based FACTS device which can act within an existing AC network or even replace parts of it. In evaluating the usefulness of HVDC it is important to remember the controllability which it adds to the power system in addition to its bulk power transfer capabilities. HVDC often provides the best of both worlds support from a neighbouring network without the problems of synchronous interconnection. Power electronic based devices enable better utilisation to be achieved of all the principal attributes of the electricity network generation, transmission and distribution. Where slow acting devices such as tap changers and circuit-breakers can be used then these are usually most economic. However, if fast or controlled response is required, for example to prevent system collapse, then FACTS power electronic facilities provide a cost effective solution. In many cases power electronics is the only way to achieve some functions, particularly with HVDC. Otherwise, they can be justified where the application requires one or more of the following attributes: rapid control action; frequent variation of output; smoothly adjustable output; and precise output.

This paper introduces the concepts of two basic switching cells, P-cell and N-cell, along with their implications in power electronic circuits. The basic switching cells exist in almost every power electronic circuit. To take advantage of these structures, this paper proposes a novel packaging method for power electronics modules. The proposed packaging method uses the basic switching cells as the unit in a module, instead of traditional anti-parallel connection of active switch and diode. This rearrangement can reduce the stray inductance in the current commutation pass; therefore, the performance and reliability of the power device module and the power electronic system can be improved. A conventional phase leg module and a proposed module are modeled. Electromagnetic simulation is carried out to extract the stray inductance from the two modules. Switching behavior under different package parasitics is studied based on Saber simulation.

Power electronics are facing continuous pressure to be cheaper and smaller, have a higher power density, and, in some cases, also operate at higher temperatures. At the same time, power electronics products are expected to have reduced failures because it is essential for reducing the cost of energy. New approaches for reliability assessment are being taken in the design phase of power electronics systems based on the physics-of-failure in components. In this approach, many new methods, such as multidisciplinary simulation tools, strength testing of components, translation of mission profiles, and statistical analysis, are involved to enable better prediction and design of reliability for products. This article gives an overview of the new design flow in the reliability engineering of power electronics from the system-level point of view and discusses some of the emerging needs for the technology in this field.

In the More Electric Aircraft (MEA) most of the hydraulic and mechanical components are replaced with electrical ones which results in a more reliable and lighter aircraft. In addition, it leads to a significant fuel saving and lower environmental impact as well as better maintainability and passenger accommodation. Studies in the field of electrification of the aircraft can be classified as the aircraft propulsion system, power generation system, power distribution system, power electronics system, actuation systems, power flow and energy management, power quality and stability issues. This paper is a review on the power electronics systems in both AC and DC power distribution architectures in more electric aircrafts.