Geometric Parameter Optimization of Switched Reluctance Machines for Renewable Energy Applications using Finite Element Analysis

The choice of SRM design depends on the specific application and performance requirements. Factors such as power output, torque characteristics, and efficiency will all influence the choice of SRM design. To find an optimal geometry, it is therefore necessary to determine the effect of each parameter such as rotor pole angle, stator pole angle, stator external diameter, rotor diameter, air gap length, rotor yoke, stator yoke and shaft diameter on the machine performance. For this reason, this paper discusses a comparative study of the geometric parameters influence on SRM performance. The analysis is performed by finite element simulations based on the variation of rotor inclination, air gap length, stator and rotor polar arc variations of three machine topologies such as the three-phase 12/8 SRM, three-phase 6/4 SRM and four-phase 8/6 SRM. For a reliable comparison, these machines must have the same basic dimensions (stator outer diameter, rotor outer diameter and length) and operate in the same magnetic circuit saturation. Graphical and numerical results of torque and magnetic flux for three SRM topologies are highlighted. The presented study aims to provide reliable results on the dimensions to be adjusted for various applications

Flux Based Sensorless Speed Sensing and Real and Reactive Power Flow Control with Look-up Table based Maximum Power Point Tracking Technique for Grid Connected Doubly Fed Induction Generator

This aim of this paper is to design controller for Doubly Fed Induction Generator (DFIG) converters and MPPT for turbine and a sensor-less rotor speed estimation to maintain equilibrium in rotor speed, generator torque, and stator and rotor voltages. It is also aimed to meet desired reference real and reactive power during the turbulences like sudden change in reactive power or voltage with concurrently changing wind speed. The turbine blade angle changes with variations in wind speed and direction of wind flow and improves the coefficient of power extracted from turbine using MPPT. Rotor side converter (RSC) helps to achieve optimal real and reactive power from generator, which keeps rotor to rotate at optimal speed and to vary current flow from rotor and stator terminals. Rotor speed is estimated using stator and rotor flux estimation algorithm. Parameters like tip speed ratio; coefficient of power, stator and rotor voltage, current, real, reactive power; rotor speed and electromagnetic torque are studied using MATLAB simulation. The performance of DFIG is compared when there is in wind speed change only; alter in reactive power and variation in grid voltage individually along with variation in wind speed

Design and Development of a Next Generation Energy Storage Flywheel

Energy storage is crucial for both smart grids and renewable energy sources such as wind or solar, which are intermittent in nature. Compared to electrochemical batteries, flywheel energy storage systems (FESSs) offer many unique benefits such as low environmental impact, high power quality, and larger life cycles. This dissertation presents the design and development of a novel utility-scale FESS that features a shaftless, hubless rotor. The unique shaftless design gives it the potential of a doubled energy density and a compact form factor. Its energy and power capacities are 100 kWh and 100 kW, respectively. The flywheel is made of high-strength steel, which makes it much easier to manufacture, assemble, and recycle. Steels also cost much less than composite materials. In addition, the system incorporates a new combination active magnetic bearing. Its working principle and the levitation control for the flywheel are presented. The development of an integrated, coreless, permanent-magnet (PM) motor/generator for the flywheel is briefly discussed as well. Initial test results show that the magnetic bearing provides stable levitation for the 5443-kg flywheel with small current consumptions. Furthermore, this dissertation formulates and synthesizes a detailed model for designing and simulating a closed-loop control system for the proposed flywheel system at high speed. To this end, the magnetic bearing supporting structure is considered flexible and modeled by finite element modeling. The magnetic bearing is characterized experimentally by static and frequency-dependent coefficients, the latter of which are caused by eddy current effects and presents challenges to the levitation control. Sensor- runout disturbances are measured and included in the model. System nonlinearities in power amplifiers and the controller are considered as well. Even though the flywheel has a large ratio of the primary-to-transversal moment of inertias, Multi-Input-Multi-Output (MIMO) feedback control demonstrates its effectiveness in canceling gyroscopic torques and stabilize the system. Various stages of PD controllers, lead/lag compensators, and notch filters are also implemented to suppress the high-frequency sensor disturbances and structural vibrations

A Study on the Integration of a High-Speed Flywheel as an Energy Storage Device in Hybrid Vehicles

The last couple of decades have seen the rise of the hybrid electric vehicle as a compromise between the outstanding specific energy of petrol fuels and its low-cost technology, and the zero tail-gate emissions of the electric vehicle. Despite this, considerable reductions in cost and further increases in fuel economy are needed for their widespread adoption. An alternative low-cost energy storage technology for vehicles is the high-speed flywheel. The flywheel has important limitations that exclude it from being used as a primary energy source for vehicles, but its power characteristics and low-cost materials make it a powerful complement to a vehicle's primary propulsion system. This thesis presents an analysis on the integration of a high-speed flywheel for use as a secondary energy storage device in hybrid vehicles. Unlike other energy storage technologies, the energy content of the flywheel has a direct impact on the velocity of transmission. This presents an important challenge, as it means that the flywheel must be able to rotate at a speed independent of the vehicle's velocity and therefore it must be coupled via a variable speed transmission. This thesis presents some practical ways in which to accomplish this in conventional road vehicles, namely with the use of a variator, a planetary gear set or with the use of a power-split continuously variable transmission. Fundamental analyses on the kinematic behaviour of these transmissions particularly as they pertain to flywheel powertrains are presented. Computer simulations were carried out to compare the performance of various transmissions, and the models developed are presented as well. Finally the thesis also contains an investigation on the driving and road conditions that have the most beneficial effect on hybrid vehicle performance, with a particular emphasis on the effect that the road topography has on fuel economy and the significance of this

Energy-Driven Analysis of Electronically-Interfaced Resources for Improving Power System Dynamic Performance

This dissertation investigates the strengthening of power system dynamics with regard to electromechanical oscillations by using electronically-interfaced resources (EIR). The dissertation addresses (1) the modeling and control design of a flywheel energy storage system and a large-scale solar PV plant. The latest is enabled to participate in oscillation damping control without the need for power curtailment. (2) A new dynamic performance evaluation and coordination of damping controller is also developed to analyze systems with several critically low damping ratios. This is studied by using the system oscillation energy to define the total action and total action sensitivity, which allow the identification of control action that benefit exited modes, rather than fixed targeted modes. Finally, (3) this dissertation proposes a solution for the site selection of EIR-based damping controllers in a planning stage. The effect of wind power variability and correlation between geographically closed wind farms is modeled to analyze the system performance and determine the site selection that maximizes the probability of dynamic performance improvement. Mathematical description as well as simulations in different multi-machine power systems show the advantages of the methods described in this work. The findings of this thesis are expected to advance the state-of-the-art of power system control by effectively and efficiently utilizing the fast power capabilities of EIR in systems with high penetration of renewable energy

Estudio comparativo de las prestaciones obtenidas mediante tres técnicas de sincronización con la red eléctrica trifásica

Para ayudar a controlar los niveles de contaminación y para un desarrollo sostenible, los sistemas distribuidos de generación de energía (también llamados microredes) basados en fuentes renovables (eólica, solar, geotérmica, etc.) están contribuyendo cada vez más en la cantidad total de energía producida en el mundo. Las microredes que se basan en electrónica de potencia están recibiendo una creciente atención en aplicaciones de red de baja tensión. Este trabajo es un estudio comparativo de las prestaciones que se pueden conseguir mediante la utilización de tres técnicas distintas para la medida de la red eléctrica trifásica. Esto es imprescindible para poder conectar convertidores de potencia trifásicos. Se ha realizado una estimación de los parámetros más significativos de la red, como son su frecuencia y la amplitud de sus armónicos. Se han evaluado las prestaciones ante situaciones adversas como son la presencia de armónicos de tensión, desequilibrio entre las fases y saltos abruptos de la frecuencia. Las simulaciones se han realizado con el programa informático Matlab-Simulink

Contributions of flywheel systems in wind power plants

The stepwise replacement of conventional power plants by renewable-based ones such as wind power plants could a ect the system behaviour and planning. First, the network stability may be compromised as it becomes less resilient against sudden changes in the loads or generator trips. This is because wind turbines are not synchronized with network frequency but they are usually connected to the grid through fast controllable electronic power converters. And second, due to the stochastic nature of wind, the electrical power generated by wind power plants is neither constant non controllable. This aff ects the network planning as the expected generation level depends on non reliable wind forecasts. Also it aff ects the power quality as the fast fluctuations of wind power can cause harmonics and flicker emissions. For these reasons, network operators gradually set up more stringent requirements for the grid integration of wind power. These regulations require wind power plants to behave in several aspects as conventional synchronized generating units. Among other requirements, it is set the provision of some ancillary services to the grid as frequency and voltage control, the capability of withstanding short-circuits and faults, and to respect some threshold level with regard to the quality of the power generated. Accordingly, energy storage systems may play an important role in wind power applications by enhancing the controllability of the output of wind power plants and providing ancillary services to the power system and thus, enabling an increased penetration of wind power in the system. This thesis focuses on the potential uses of flywheel energy storage systems in wind power. The thesis introduces the basis of several energy storage systems as well as identi es their applications in wind power based on an extensive literature review. It follows with the presentation of the design and setting up of a scale-lab flywheel-based energy storage system. From this work, research concentrates on the application of flywheel devices for power smoothing of wind power plants. The developed concepts are proved by simulations but also experimentally using the above mentioned scale-lab test bench. In particular, research focuses on the de nition of an optimization criteria for the operation of flywheel devices while smoothing the wind power, and the design and experimental validation of the proposed control algorithms of the storage device. The last chapters of the thesis research on the role of wind power plants in system frequency control support. In this sense, an extensive literature review on the network operator's requirements for the participation of wind power plants in system frequency control related-tasks is off ered. Also, this review covers the proposed control methods in the literature for enabling wind turbines to participate in system frequency control. The results of this work open the door to the design of control systems of wind turbines and wind power plants for primary frequency control. The contribution of flywheel devices is also considered. Results highlight the tremendous potential of energy storage systems in general for facilitating the grid integration of wind power plants. Regarding the uses of flywheel devices, it is worth noting that some of their characteristics as the high-ramp power rates can be exploited for reducing the variability of the power generated by wind turbines, and thus for improving the quality of the power injected to the grid by wind power plants. Also, they can support wind power plants to ful l the requirements for their participation in system frequency control support related tasks.El progressiu despla cament de plantes de generaci o convencionals per part de plantes de generaci o de tipus renovable, com els parcs e olics, pot afectar el comportament i la plani caci o del sistema el ectric. Primer, l'estabilitat pot ser compromesa ja que el sistema el ectric resulta m es vulnerable davant canvis abruptes provocats per les c arregues del sistema o desconnexions no programades de generadors. Aix o es degut a que les turbines e oliques no estan sincronitzades amb la freqü encia el ectrica del sistema ja que la seva connexi o es a trav es de convertidors electr onics de pot encia. Segon, degut a la gran variabilitat del vent, la pot encia el ectrica generada per les turbines e oliques no es constant ni controlable. En aquest sentit, la qualitat de la pot encia del parc e olic es pot veure compromesa, ja que es poden detectar nivells apreciables d'harm onics i emissions de "flicker" degudes a les r apides variacions de la pot encia generada pel parc e olic. Per aquests motius, els operadors dels sistemes el ectrics fan gradualment m es restrictius els requeriments de connexi o dels parcs e olics al sistema el ectric. Aquestes regulacions requereixen als parcs e olics que es comportin en molts aspectes com plantes de generaci o convencional. Entre d'altres requeriments, els parcs e olics han de proveir serveis auxiliars per a la operaci o del sistema el ectric com tamb e el suport en el control dels nivells de tensi o i freqü encia de la xarxa; oferir suport durant curtcircuits; i mantenir uns nivells m nims en la qualitat de la pot encia generada. Els sistemes d'emmagatzematge d'energia poden millorar la controlabilitat de la pot encia generada pels parcs e olics i ajudar a aquests a proveir serveis auxiliars al sistema el ectric, afavorint aix la seva integraci o a la xarxa. Aquesta tesi tracta l'aplicaci o en parcs e olics dels sistemes d'emmagatzematge d'energia basats en volants d'in ercia. La tesi introdueix les bases de diversos sistemes d'emmagatzematge i identi ca les seves potencials aplicacions en parcs e olics en base a una extensa revisi o bibliogr a ca. El treball continua amb la posta a punt d'un equipament de laboratori, que con gura un sistema d'emmagatzematge d'energia basat en un volant d'in ercia. Següents cap tols de la tesi estudien l'aplicaci o dels volants d'in ercia per a esmorteir el per l fluctuant de la pot encia generada pels parcs e olics. Els treballs es focalitzen en la de nici o dels criteris per a la operaci o optima dels volants d'in ercia per la seva aplicaci o d'esmorteir el per l fluctuant de potencia e olica, i tamb e en el disseny i validaci o experimental dels algoritmes de control desenvolupats per governar el sistema d'emmagatzematge. Els cap tols finals de la tesi tracten sobre el suport al control de freqü encia per part dels parcs e olics. S'ofereix una extensa revisi o bibliografica respecte els requeriments indicats pels operadors del sistema el ectric en aquest sentit. A m es, aquesta revisi o cobreix els m etodes de control dels parcs e olics i turbines e oliques per la seva participaci o en el suport al control de freqü encia. Les conclusions extretes serveixen per proposar sistemes de control de parcs e olics i de turbines e oliques per proveir el servei de control de freqüencia. Aquest treball, tamb e contempla la inclusi o de volants d'in ercia en els parcs e olics. Dels resultats de la tesi se'n dedueix l'important potencial dels sistemes d'emmagatzematge d'energia per a afavorir la integraci o a la xarxa dels parcs e olics. La controlabilitat de la pot encia dels volants d'in ercia, afavoreix el seu us per reduir la variabilitat de la pot encia generada pels parcs e olics, millorant aix la qualitat de pot encia del mateix. A m es, els volants d'in ercia poder ajudar als parcs e olics a complir amb els requeriments per a la seva integraci o a xarxa, com la participaci o en el control de freqüencia del sistema el ectric