Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 43 for “"frequency stability"”.
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Frequency stability in a compact, deployable optical atomic clock
… lasers, ultra-fast lasers, and optical frequency combs in the last several decades have enabled a new generation of atomic clocks based on optical transitions as opposed to microwave transitions While optical atomic clocks in the laboratory outperform microwave standards by orders of …
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Frequency Stability Constrained Grid Operation with High Penetration of Renewables
… presents considerable challenges in maintaining frequency stability, especially following disturbances.</p> <p>Two possible solutions are proposed to address the first issue. Firstly, a speedy real time generation dispatch can be scheduled to allocate generation resources within short time …
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Investigating the low-frequency stability of BiSON's resonant scattering spectrometers
… of the thesis is the study of low-degree low-frequency solar p modes from the analysis of high-resolution power spectra generated from 20 years of high-quality data collected by the Birmingham Solar Oscillations Network (BiSON) Resonant Scattering Spectrometers (RSS). To that end we present a …
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Protection, Automation, and Frequency Stability Analysis of a Laboratory Microgrid System
… and a centralized SEL controller to automate frequency regulation through load shedding, power factor correction, generator and utility synchronization, and relay protection group switching.</p>
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Virtual Inertia Emulation to Improve Dynamic Frequency Stability of Low Inertia Microgrids
… nature of photovoltaic systems, dynamic frequency stability issues arise in microgrids with large photovoltaic systems. This limits the maximum amount of photovoltaic systems that can be penetrated in the microgrid. In order to increase the penetration of photovoltaic systems, the dynamic …
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Frequency stability of a helium neon laser system with external cavity control
… spectral purity requires a high degree of frequency stabilization and laser mode control. In the past few years much effort has been expended in attempts to devise and test various methods of frequency stabilization. This investigation lists a number of these methods employed over the past …
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COHERENCE AND FREQUENCY STABILITY OF SEMICONDUCTOR LASERS UNDER CW OPERA TI ON AND MODULATION
… work is an investigation into the coherence and frequency stability of semiconductor lasers. The work begins with a brief review of the many varied techniques which have been proposed to achieve highly coherent. and stable semiconductor lasers. A computer simulation model of a semiconductor laser …
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Compensating for the effects of reduced synchronous inertia on frequency stability using virtual synchronous generators
… large synchronous generators which have provided frequency stability through their inertia and governor responses. As more renewable energy sources (RES), particularly wind and solar, are added to the grid, they displace synchronous generators. Many of these RES generators do not inherently …
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Development of ultra-stable MEMS oscillators with 10⁻¹¹-level frequency stability via dual-mode temperature compensation
This thesis investigates the long-term frequency stability limits of encapsulated silicon MEMS resonators and develops two clock architectures to achieve high-precision, low-drift operation suitable for timing applications. The study is based on an encapsulated, heavily boron-doped Lamé-mode …
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Design Technique for Analog Temperature Compensation of Crystal Oscillators
… the quartz crystal has been used for precise frequency control. In the increasingly popular field of wireless communications, available frequency spectrum is becoming very limited, and therefore regulatory agencies have imposed tight frequency stability requirements. There are generally two …
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Low-Frequency Series Loaded Resonant Inverter Characterization
… mainly attributed to a load dependent resonant frequency. Recent advancements in power electronics propose an electronically tunable inductor suited for low frequency applications [24], [25]; as a consequence, frequency stability in resonant inverters is achievable within a limited load range. …
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Wind farm control and modelling to provide grid primary response and meet O&M requirements
… wind farms will need to provide services such as frequency support to match supply and demand. From the viewpoint of the wind farm operators, wind farms will need to be operated in such a manner as to maximise the return of investment. To meet these grid and operator requirements a wind farm …
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Time and Frequency Transfer in a Coherent Multistatic Radar using a White Rabbit Network
… radars require accurate and stable time and frequency transfer (TFT) for range and Doppler estimation. TFT techniques based on global navigation satellite systems (GNSS), have been favoured for several reasons, such as enabling node mobility through wireless operation, geospatial referencing, …
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Modeling of In(0.49)Ga(0.51)P/GaAs Heterojunction Bipolar Transistors for ADC and MMIC Circuit Design
… These are presented as a means to enhance the frequency stability of the circuit. Design architectures based on the resonator structure are presented. In addition, to improve the tuning range of the state-of-the-art oscillator, several wave-guide lengths were adjusted. These are included as …
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Depletion, quantum jumps, and temperature measurements of ⁸⁸Sr⁺ ions in a linear Paul Trap
… laser, we measured an unsuitable experimental stability of 10 MHz over 5 minutes. A completely new monolithic laser system was built, providing better environmental isolation and a frequency stability of at least 1 MHz over 5 minutes. Using this laser, we were able to observe depletion and …
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A Narrow-Linewidth Laser at 1550 nm Using the Pound-Drever-Hall Stabilization Technique
Linewidth is a measure of the frequency stability of any kind of oscillator, and it is a defining characteristic of coherent lasers. Narrow linewidth laser technology, particularly in the field of fiber-based infrared lasers, has progressed to the point where highly stable sources are commercially …
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A novel zonal adaptive DG anti-islanding protection scheme to enhance future system stability using real-time inertia estimates
… disturbances, can incur negative power system stability issues. With particular attention given to the anticipated reduction and variation of system inertia, concerns are growing with respect to power system frequency stability following large disturbances. This is attributed to the potential …
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Changes to system inertia and the impact on frequency response requirements
… concerns about the assurance of frequency stability and the adequacy ofdynamic frequency responses at low inertia. In islanded power systems, like those ofIreland and Great Britain (GB), understanding the issues posed and deploying effectivesolutions benefit from an investigation …
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Leak detection in power plant heat recovery steam generators utilizing medical radionuclides
… turn up and turn down is required to ensure grid frequency stability. Modern gas turbines operating in combined cycle mode can achieve fast response ramp rates typically in the region of 40 MWe/min (turbine, 2018), this places increased stress on thick walled steam turbine and boiler components, …
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Synchronous Condensers and Grid-Forming Control for the Integration of Inverter-Based Resources in Weak Grids
… of strength and inertia increases the risk of instability during contingencies, e.g., short-circuit faults. This dissertation investigates and proposes methodologies to enhance the stability of IBRs by leveraging synchronous condensers (SC) and grid-forming control. First, it presents an …
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