Monitoring and operation of a synchronous generator on short circuit on the rotor of a combined cycle power plant

The aim of this project is the monitoring of a round rotor synchronous generator in a C.C.G.T. power plant, through an innovative digital supervision system that utilizes a magnetic flux probe and a grounding device. Substantially the monitoring system will deploy a magnetic flux probe because, from an evaluation of the flux generated by the rotor winding (and other signals), it is possible to understanding if there are shorted turns on the rotor windingopenEmbargo per motivi di segretezza e/o di proprietà dei risultati e informazioni di enti esterni o aziende private che hanno partecipato alla realizzazione del lavoro di ricerca relativo alla tes

The NASA Scientific and Technical Information System: Its scope and coverage

Subjects of scientific and technical documents considered for inclusion in NASA's information bank are broadly summarized under the various categories used in Scientific and Technical Aerospace Reports and International Aerospace Abstracts. A general definition of each category is followed by a list of the aspects of each subject which are of exhaustive, selective, or negative interest because of their relevance to aerospace science and technology and to other NASA projects

Use, Operation and Maintenance of Renewable Energy Systems:Experiences and Future Approaches

The aim of this book is to put the reader in contact with real experiences, current and future trends in the context of the use, exploitation and maintenance of renewable energy systems around the world. Today the constant increase of production plants of renewable energy is guided by important social, economical, environmental and technical considerations. The substitution of traditional methods of energy production is a challenge in the current context. New strategies of exploitation, new uses of energy and new maintenance procedures are emerging naturally as isolated actions for solving the integration of these new aspects in the current systems of energy production. This book puts together different experiences in order to be a valuable instrument of reference to take into account when a system of renewable energy production is in operation

Monitoring and control requirement definition study for Dispersed Storage and Generation (DSG), volume 1

Twenty-four functional requirements were prepared under six categories and serve to indicate how to integrate dispersed storage generation (DSG) systems with the distribution and other portions of the electric utility system. Results indicate that there are no fundamental technical obstacles to prevent the connection of dispersed storage and generation to the distribution system. However, a communication system of some sophistication is required to integrate the distribution system and the dispersed generation sources for effective control. The large-size span of generators from 10 KW to 30 MW means that a variety of remote monitoring and control may be required. Increased effort is required to develop demonstration equipment to perform the DSG monitoring and control functions and to acquire experience with this equipment in the utility distribution environment

Active power control response from large offshore wind farms

This thesis was submitted for the degree of Doctor of Engineering and awarded by Brunel University LondonThe GB power system will see huge growth in transmission connected wind farms over the next decade, driven by European clean energy targets. The majority of the UK’s wind development is likely to be offshore and many of these wind farms will be interfaced to the grid through power converters. This will lead to a loss of intrinsic inertia and an increasing challenge for the system operator to keep grid frequency stable. Given this challenge, there is increasing interest in understanding the capabilities of converter control systems to provide a synthesised response to grid transients. It is interesting to consider whether this response should be demanded of wind turbines, with a consequential reduction in their output, or if advanced energy storage can provide a viable solution. In order to investigate how large offshore wind farms could contribute to securing the power system, wind turbine and wind farm models have been developed. These have been used to design a patented method of protecting permanent magnet generator’s converters under grid faults. Furthermore, these models have enabled investigation of methods by which a wind turbine can provide inertial and frequency response. Conventionally inertial response relies on the derivative of a filtered measurement of system frequency; this introduces either noise, delay or both. This research proposes alternative methods, without these shortcomings, which are shown to have fast response. Overall, wind farms are shown to be technically capable of providing both high and low frequency response; however, holding reserves for low frequency response inevitably requires spilling wind. Wind’s intermittency and full output operation are in tension with the need of the power system for reliable frequency response reserves. This means that whilst wind farms can meet the technical requirements to hold reserves, they bid uncompetitive prices in the market. This research shows that frequency response market prices are likely to rise in future suggesting that the Vanadium Redox Flow Battery is one technology which could enter this market and also complement wind power. Novel control incorporating fuzzy logic to manage the battery is developed to allow a hybrid wind and storage system to aggregate the benefits of frequency response and daily price arbitrage. However, the research finds that the costs of smoothing wind power output are a burden on the store’s revenue, leading to a method of optimising the combined response from an energy store and generator that is the subject of a patent application. Furthermore, whilst positive present value may be derived from this application, the long payback periods do not represent attractive investments without a small storage subsidy.The Engineering and Physical Sciences Research Council (EPSRC) and GE Energ

Monitoring systems for managing natural resources: economics, indicators and environmental externalities in a Costa Rican watershed

The worsening degradation of natural resources urgently requires the adoption of more sustainable management practices. This need has led to growing interest and investment in monitoring systems for tracking the condition of natural resources. This study is concerned with the design of monitoring systems that have direct relevance for the management of natural resources. We call these Policy Relevant Monitoring Systems (PRMS). Such systems have several key characteristics. They provide: a) a decision framework for selecting resource problems to monitor that offer potentially large social payoffs relative to the costs of monitoring, b) timely, including early warning information on emerging problems, c) a means of identifying the causes of an emerging problem, d) an analytical framework for identifying options for corrective action, e) an institutional framework for achieving ownership among key stakeholders (the resource users and those affected by the resource use) and agreement about emerging problems, the corrective actions to take, and effective implementation, and f) a built-in mechanism for learning from past experience to improve the performance of the monitoring system over time. The approach is developed and illustrated through detailed examination of the Arenal-Tempisque watershed in Costa Rica. This watershed exhibits classic multiple user and externality problems: deforestation by dairy and cattle farmers in the upper watershed leads to soil erosion and siltation of the various reservoirs that feed an important hydro-electric power generation system, and agro-chemical use by irrigated farmers has adverse impacts on a highly valued wetlands park and on wildlife and fishing in the lower reaches of the watershed.Natural resources., Environmental degradation., Costa Rica, Watershed management.,

Monitoring and control requirement definition study for Dispersed Storage and Generation (DSG). Volume 2, appendix A: Selected DSG technologies and their general control requirements

A consistent approach was sought for both hardware and software which will handle the monitoring and control necessary to integrate a number of different DSG technologies into a common distribution dispatch network. It appears that the control of each of the DSG technologies is compatible with a supervisory control method of operation that lends itself to remote control from a distribution dispatch center

A modelling approach for evaluating impacts of hydropeaking in a sub-arctic river

Abstract. The release of pulses of water to increase hydroelectric power production at hydropower dams to meet daily peaks in electricity demands is called hydropeaking. Due to energy supply and demand fluctuations, the energy markets direct hydropower companies to balance load fluctuations through variations in power generation which result in flow regulation. More recently, this regulation is being carried out at shorter time intervals i.e., intra-daily and intra-hourly levels. The hydropeaking phenomenon increases drastically at shorter time intervals, severely impacting the riverine and riparian ecosystem. Social, economic, and ecological impacts arise from short-term hydropeaking. Furthermore, recreational services offered by the river are also impacted. This research develops a novel methodology for assessing these impacts in a strongly regulated sub-arctic river in Finland, i.e., Kemijoki River, Ossauskoski-Tervola reach. The methodology combines assessment of seasonal variations in sub-daily hydropeaking, two-dimensional hydrodynamic modelling, and a high-resolution land cover map developed through supervised land use classification via a machine learning algorithm. The results obtained include; the identification of a zone of influence of hydropeaking at sub-daily levels during each season, the total and class-wise area affected during each peaking event, and vulnerability zonation for water-based recreation in the river reach. The overall area of reach affected by peaking in Winter was (1.05 km2), Spring (0.96 km2), Summer (1.39 km2), and Autumn (0.66 km2). A vulnerability mapping was also carried out for the suitability of water-based recreation in the study reach. The novel methodology developed in this research which defines the vulnerable zone of hydropeaking can be used as the first step in detailed impacts assessment studies such as those for impacts on fish habitat and sediment transport processes in the river. The hydropeaking-influenced zone can be used to set thresholds for ecological flows and ramping rates downstream of power stations and opens avenues for future research, development, and policy endeavors for riparian ecosystem impact assessment and mitigation

Review of primary frequency control requirements on the GB power system against a background of increasing renewable generation

This thesis was submitted for the degree of Doctor of Engineering and awarded by Brunel University.The system frequency of a synchronous power system varies with the imbalance of energy supplied and the electrical energy consumed. When large generating blocks are lost, the system undergoes a frequency swing relative to the size of the loss. Limits imposed on the magnitude of frequency deviation† prevent system collapse. Operation of frequency responsive plant to control frequency, results in lower machine efficiencies. Changes to the generation mix on the British transmission system have occurred in the past ten years, when the response requirement was last reviewed. Future increased levels of wind turbines‡ will alter the operational characteristics of the system and warrant investigation. A process to optimise the response requirements while maintaining statutory limits on frequency deviation has been identified. The method requires suitable load and generator models to replicate transmission system performance. A value to substitute for current load sensitivity to frequency has been presented from empirical studies. Traditional coal fired generator models have been improved with additional functions to provide a comparable response with existing units. A novel combined cycle gas turbine model using fundamental equations and control blocks has also been developed. A doubly fed induction generator model, based on existing literature, has been introduced for representing wind turbine behaviour in system response studies. Validation of individual models and the complete system against historic loss events has established confidence in the method. A review of the current system with the dynamic model showed that current primary response requirements are inadequate. The secondary response requirements generally show a slight reduction in the holding levels. Simulations including extra wind generation have shown that there is potential to reduce the primary response requirement in the future. The secondary response requirements are maintained with added wind farms