The objective of the project was to develop models and methods suitable for computer implementation. In particular, this work has been devoted to generation scheduling of a power system with a sizeable amount. of hydro energy. Optimal operation planning of hydrothermal power systems aims at minimizing incurred production costs while supplying customer de­mand. The planning horizon may vary from one day to several years and the associated planning problems are categorized as short term, seasonal and long term operation planning. The topic of this thesis is short term operation planning. In this planning, it is necessary to use detailed models of the different parts of the power system. These include models of cas­caded reservoirs in a multi-river system as we11 as a representa­tion of the nonlinear generating characteristics of the hydro plants. he thermal generating units are modelled using linear production cost curves and by recognizing various technical constraints asso­ciated with the operation of these plants. Effects on the optimal operating strategy caused by interregional transmission capacity limitations are also accounted for by the model. These constraints are modelled to main1y affect the hydro plant operation. / <p>QC 20161207</p>

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The thesis presents models for short term planning (24 hours) of a hyro dominated hydrothermal power system. The purpose of the models is to minimizae the system operation costs to provide a forecasted load and keep enough spinning reserve. / This thesis presents models for short term planning (24 hours) of a hydro dominated hydrothermal power system. The purpose of the models is to minimize the system operation cost to provide a forecasted load and keep enough spinning reserve.   The thesis focuses on two issues in hydro power modelling. The first issue is the relationship between water discharged and power generated. This relationship is a non-linear and non-convex function. If the plant has several units, the efficiency of the plant will have local maximums, so called local best-efficiency points. The second issue is to take into account the cost of start-ups of hydro units in the planning.   The hydro model is mixed-integer. Discharg􀁐s are allowed at zero flow, the local best-efficiency points and on the continuous part between the local best-efficiency point with the highest flow and the point with maximum flow. This last continuous part is modelled as a linear function. In order to get data for the start-up cost a survey among the largest power producers in Sweden has been made, where three questions about start-ups of hydro power units has been asked: What causes the costs in the start-up?, How much does a start-up cost? and How do start-ups effect the short-term scheduling strategies of power producers in Sweden? The results show that a fair estimate of the start-up cost is about $3/MW nominal output. For the thermal plants a standard model with polynomial operation cost, start-up costs and ramp-rate constraints has been used. The model also includes the possibilities of purchasing and selling power to forecasted prices.   The planning problem is formulated as a mathematical programming problem. The solution technique uses Lagrange relaxation to decompose the problem into subproblems. There will be one subproblem for each hydro and thermal plant. In order to find good feasible solutions a heuristic technique to change the integer variables in the hydro system has been developed. The Lagrange multipliers are updated with the subgradient method.   The models are tested in three different load situations; a winter day (heavy load), an autumn day (medium load) and a summer day (light load). The result shows that the method gives near optimal schedules in reasonable computation time in cases with a normal part of the thermal units committed. The assumed start-up cost results in that hydro units almost never are started or stopped for one hour only. / <p>QC 20161206</p>

The thesis contains the results of a reseach project on application of mathematical programming methods to short-term operation planning of large hydrothermal power systems. The project was aimed at devoeloping efficient solution techniques that are practially applicable to large systems. The problem is modeled as a large mixed integer program. / This thesis contains the results of a research project on application of mathematical programming methods to short-term operation planning of large hydrothermal power systems. The work was carried out at the Department of Electric Power System Engineering of the Royal Institute of Technology, Stockholm, Sweden.   The project was aimed at developing efficient solution techniques that are practically applicable to large scale power systems. The thesis consists of seven chap­ters and four appendices.   The increasing importance and the magnitude of the expenditures associated with it have created an urgent necessity to operate the electric energy systems in an optimal economic manner. The optimal operation planning, as explained in chapter 1, can be divided into several subproblems which are more computationally manageable. The short-term operation planning contains two of these subproblems, namely; weekly and daily operation planning.   The problem, as modeled in chapter 2 for systems with a considerable amount of hydro, is a large mixed integer program. The objective for this problem is the produc­tion cost of the thermal plants. The optimization hori­zon varies from one week to one day, and the discretiza­tion intervals are normally chosen between one to several hours.   In chapter 3, Lagrangian relaxation technique and Benders' method are introduced to decompose the problem with re­spect to hydro and thermal systems. This makes it poss­ible to exploit the special characteristics of each system.   The hydro problem is a large linear program with embedded network structure. In chapter 4, several solution techniques are introduced that exploit this special structure of the large number of constraints involved. The small nonlinearities of hydro problem and· head variation are also treated in this chapter.   The thermal problem involves integer variables. In cha­ter 5, the special structure of this problem is consider­ed, which results in a considerable amount of reductions. Branch and bound, shortest path, and discrete dynamic programming methods are considered for solution of thermal system. This chapter is extended to consider hydro­thermal power system with low amounts of hydro.   Chapter 6 concerns network labeling system, network flow algorithms, and sparsity techniques, which were considered in the implementation of the algorithms.   Finally, the test results and conclusions from application of different techniques are considered and discussed in chapter 7. The Swedish System has been used to prove the applicability and efficiency of the developed techniques. The short-term model can be used in operation, as an engineering tool for decision making, and in planning, to analyze alternative planning schemes. / <p>QC 20161206</p>

Global environmental concerns associated with conventional energy generation have led to the rapid growth of wind energy applications in electric power systems. Growing demand for electrical energy and concerns associated with limited reserves of fossil fuels are also responsible for the development and increase in wind energy utilization. Many jurisdictions around the world have set high wind penetration targets in their energy generation mix.<p> The contribution of wind farms to the overall system reliability is limited by the uncertainty in power output from the highly variable energy source. High wind penetration can lead to high risk levels in power system reliability and stability. In order to maintain the system stability, wind energy dispatch is usually restricted and energy storage is considered to smooth out the fluctuations and improve supply continuity. The research work presented in this thesis is focused on developing reliability models for evaluating the benefits associated with wind power and energy storage in electric power generating systems. An interactive method using a sequential Monte Carlo simulation technique that incorporates wind farm and energy storage operating strategies is developed and employed in this research. Different operating strategies are compared and the resulting benefits are evaluated. Important system impacts on the reliability benefits from wind power and energy storage are illustrated. Hydro facilities with energy storage capability can alleviate the impact of wind power fluctuations and also contribute to system adequacy. A simulation technique for an energy limited hydro plant and wind farm coordination is developed considering the chronological variation in the wind, water and the energy demand. The IEEE four-state model is incorporated in the developed technique to recognize the intermittent operation of hydro units. Quantitative assessment of reliability benefits from effective utilization of wind and water resources are conducted through a range of sensitivity studies. The information provided and the examples illustrated in this thesis should prove useful to power system planners and wind developers to assess the reliability benefit from utilizing wind energy and energy storage and the coordination between wind and hydro power in electric power systems.

Global environmental concerns associated with conventional energy generation have led to the rapid growth of wind energy applications in electric power systems. Growing demand for electrical energy and concerns associated with limited reserves of fossil fuels are also responsible for the development and increase in wind energy utilization. Many jurisdictions around the world have set high wind penetration targets in their energy generation mix.<p> The contribution of wind farms to the overall system reliability is limited by the uncertainty in power output from the highly variable energy source. High wind penetration can lead to high risk levels in power system reliability and stability. In order to maintain the system stability, wind energy dispatch is usually restricted and energy storage is considered to smooth out the fluctuations and improve supply continuity. The research work presented in this thesis is focused on developing reliability models for evaluating the benefits associated with wind power and energy storage in electric power generating systems. An interactive method using a sequential Monte Carlo simulation technique that incorporates wind farm and energy storage operating strategies is developed and employed in this research. Different operating strategies are compared and the resulting benefits are evaluated. Important system impacts on the reliability benefits from wind power and energy storage are illustrated. Hydro facilities with energy storage capability can alleviate the impact of wind power fluctuations and also contribute to system adequacy. A simulation technique for an energy limited hydro plant and wind farm coordination is developed considering the chronological variation in the wind, water and the energy demand. The IEEE four-state model is incorporated in the developed technique to recognize the intermittent operation of hydro units. Quantitative assessment of reliability benefits from effective utilization of wind and water resources are conducted through a range of sensitivity studies. The information provided and the examples illustrated in this thesis should prove useful to power system planners and wind developers to assess the reliability benefit from utilizing wind energy and energy storage and the coordination between wind and hydro power in electric power systems.

The focus of the thesis study is to conduct feasibility studies for the upgrading of Lusiwasi Hydro Power Station in Serenje District of Zambia. The study was undertaken from January to August 2009. The following were the main activities of the study: 1. Conducting literature review 2. Conducting site inspections to the project site 3. Estimation of the load 4. Estimation of power potential based on the flows monitored by the existing gauging station.   Literature review was done on the feasibility studies which were conducted in 1997 by the Consultant Knight Piesold Limited .The feasibility study focused on the need to rehabilitate the Power Station to ensure that it operated at its installed capacity of 12MW. A review was also done on hydrological data from DWA under Ministry of Energy and Water Development and ZESCO. The review process was further supplemented by direct observations and interviews during the site inspections.   As part of site inspection and data collection, two field trips were conducted on the project site, the main objectives of the field trips were to gather data and to familiarise with the operations of the hydro Power Station.   Due to non availability of records for the dam levels, reservoir volume and catchment basin hydrology, a method is adopted in this study to use records from the existing gauging station, which has been in existence since 1965, to estimate potential hydro power. Five different scenarios are developed using Hydata and Microsoft Excel programs to confirm whether the flows from the gauging station could support further expansion of the Power Station. From the results, the model revealed that the flows could only manage to sustain a plant capacity of 12MW with a yearly plant availability of 67%. However, it was further observed that if the spilled water from the intake weir dam is used to generate power, an additional 30MW could be generated. Therefore the total installed capacity is estimated at 42MW.     The main recommendation and future work for the project include the need to ensure that the proposed Power Station operates as a mid merit station i.e. as base and peaking station in order to avoid significant fluctuation of the water level in the proposed dam reservoir. The other recommendations include the need to install new gauging stations on the upstream of the existing dam so that the hydrology of the catchment area is monitored. Furthermore, there is also need for ZESCO to consider rehabilitating the Power Station as a matter of urgency to ensure that the station operates at its installed capacity of 12MW.

A project to suggest an alternative to small scale hydro power at the old power plant in Långforsen, Jämtland, Sweden. Using excavation as a tool and raw materials from the site, the aim is to take the visitor into nature by using choreographed movement through the site, close to nature shelters, and a visitor center to tie it all together.

Given the unstable state of the environment, there is an undeniable need for the development of sustainable technologies. This need affects all areas of everyday life, even the shower. Modern shower systems result in energy waste in the form of heat, which can be minimized through the implementation of a heat exchanger. In cooperation with Consat SES this project developed a system to implement a heat exchanger using an in-shower water transportation pipe. A fitting non-electrical pump and motor were also chosen. To develop these elements a general design methodology of defining the problem, identifying the solution space, developing concepts, testing concepts and proposing a design, was used with adaptations for the component at hand. By following this strategy for each component and then reviewing the system as a whole, a new shower system was developed with a trapezoidal water transport pipe, a wing pump, and a turgo turbine.

Synchronous generators used for hydro power and nuclear power is a well known topology but there is a vast amount of intricate technologies and methods to making them function properly. This masters thesis covers the development, implementation and verification of a magnetisation system for a synchronous generator. The software implementation is made in the LabVIEW programming environment and uses a high performance CompactRIO with an FPGA for measurements, calculation and output control signals. Together with several peripheral devices, the CompactRIO forms an excitation system and most importantly, an automatic voltage regulator. This system keeps the output voltage of the generator stable and has a variety of safety features such as over excitation limits, under excitation limits and a V/Hz limiter. The resulting system successfully monitors and controls the generator characteristics and the controllers, based on PI controllers, have short rise times, low overshoot and no significant static error. This magnetisation system was verified on a 185 kW synchronous machine and all functions showed satisfying results with the exception of the implemented power system stabiliser which need to be re-tuned.