Solar energy is one of the most promising renewable resources that can be used to produce electric energy through photovoltaic process. A significant advantage of photovoltaic (PV) systems is the use of the abundant and free energy from the sun. However, these systems still face major obstacles that hinder their widespread use due to their high cost and low efficiency when compared with other renewable technologies. Moreover, the intermittent nature of the output power of PV systems reduces their reliability in providing continuous power to customers. In addition, the fluctuations in the output power due to variations in irradiance might lead to undesirable performance of the electric network. The support of governments, electric utilities, researchers and consumers is the key to overcoming the aforementioned obstacles and enhancing the maturity of the technology in this field. The primary objective of the research proposed in this thesis is to facilitate increasing the penetration levels of PV systems in the electric network. This can be achieved by quantifying and analyzing the impacts of installing large grid-connected photovoltaic systems on the performance of the electric network accurately. To achieve this objective, the development of a new and intelligent method is introduced. The method utilizes the available data efficiently to produce accurate realistic results about the performance of the electric network without overestimating or underestimating the impacts of the PV system. The method utilizes historical environmental data collected over a number of years to estimate the profile of the output power of the PV system. In addition, the method considers the actual data of the electric network. Hence, the interaction between the output power of the PV system and the electric network components can be simulated to identify the possible operational problems. After identifying the operational problems that might arise due to installing PV systems, especially due to power fluctuations, different strategies that can mitigate these problems are studied in detail. These strategies include installation of energy storage devices, use of dump loads, and operation below the maximum power point. Upon studying the mitigation strategies, their economical aspects are investigated. The economical aspect is crucial for PV systems because of their high cost, which is reflected on the price of the energy produced by them. The presented research integrates techniques from different fields of engineering such as data mining, mathematical optimization and power systems. This research is expected to contribute to the advancement of PV technology by introducing methods that will help in carrying out in-depth evaluation of the performance of PV systems and providing feasible solutions to the operational problems that might arise from the installation of these systems.

Solar energy is one of the most promising renewable resources that can be used to produce electric energy through photovoltaic process. A significant advantage of photovoltaic (PV) systems is the use of the abundant and free energy from the sun. However, these systems still face major obstacles that hinder their widespread use due to their high cost and low efficiency when compared with other renewable technologies. Moreover, the intermittent nature of the output power of PV systems reduces their reliability in providing continuous power to customers. In addition, the fluctuations in the output power due to variations in irradiance might lead to undesirable performance of the electric network. The support of governments, electric utilities, researchers and consumers is the key to overcoming the aforementioned obstacles and enhancing the maturity of the technology in this field. The primary objective of the research proposed in this thesis is to facilitate increasing the penetration levels of PV systems in the electric network. This can be achieved by quantifying and analyzing the impacts of installing large grid-connected photovoltaic systems on the performance of the electric network accurately. To achieve this objective, the development of a new and intelligent method is introduced. The method utilizes the available data efficiently to produce accurate realistic results about the performance of the electric network without overestimating or underestimating the impacts of the PV system. The method utilizes historical environmental data collected over a number of years to estimate the profile of the output power of the PV system. In addition, the method considers the actual data of the electric network. Hence, the interaction between the output power of the PV system and the electric network components can be simulated to identify the possible operational problems. After identifying the operational problems that might arise due to installing PV systems, especially due to power fluctuations, different strategies that can mitigate these problems are studied in detail. These strategies include installation of energy storage devices, use of dump loads, and operation below the maximum power point. Upon studying the mitigation strategies, their economical aspects are investigated. The economical aspect is crucial for PV systems because of their high cost, which is reflected on the price of the energy produced by them. The presented research integrates techniques from different fields of engineering such as data mining, mathematical optimization and power systems. This research is expected to contribute to the advancement of PV technology by introducing methods that will help in carrying out in-depth evaluation of the performance of PV systems and providing feasible solutions to the operational problems that might arise from the installation of these systems.

In 1990 Flödeskommittén released new guidelines which redefined the method used to determine design flows. The method, combined with more complete measurements of flow variations, has resulted in higher design flows which in turn call for increases in the discharge capacity of hydropower plants. This work is still in progress. Since many Swedish hydropower stations were constructed in the 1950's and 60's they require modernization. Today Statkraft owns and operates 55 hydropower stations in Sweden several of which have a discharge capacity below the design flow. For this reason, the dam safety of these hydropower stations is reduced. According to current guidelines the turbine flow is not added to the discharge capacity since the availability of the electrical grid is not guaranteed during extreme flows. When the electric grid is unavailable the generator has no load and cannot produce an electric torque. Without the electric torque the turbine accelerates which may result in equipment failure. This thesis considers the introduction of an alternative local load where the generator power can be dumped as heat, hence termed dump load. The dump load has the potential to increase the discharge capacity by adding the turbine flow. However, operation of the dump load requires the availability of the generator and turbine, making the discharge capacity dependent on the status of the plant. In turn, achieving a sufficient discharge capacity is of primary concern to dam operators since it determines dam safety. Consequently, this thesis evaluates the effects on dam safety when utilizing a local load to increase the discharge capacity. Three different designs were evaluated; a medium to high voltage electrode water boiler, electrodes submerged in the river and a low voltage electric water boiler. The evaluation shows that all three designs are feasible and can be used to increase the discharge capacity provided the generator and turbine have high availability. The complexity and number of components constituting the dump load should be minimized to reduce the risk of malfunctions and redundancy should be introduced for key components when feasible. The dump load power should be controlled using voltage regulation but further work is required to determine the specifics of this governor. The results also show that the cost of the dump load is a fraction of the cost of a new spillway. However, the topic is controversial and the dump load requires practical testing in order to evaluate operational reliability.

In hydropower plants, a local load, also known as a dump load, could be installed to balance theelectrical grid by consuming excessive power. This enhances the dam safety. A design for asmall-scaled three-phase dump load is presented in this thesis. The designed model is built andevaluated through simulations and experiments. The results show that the system is purelyresistive. The per phase resistance of the model can be calculated with geometrical analysis ofthe design.