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Summary: In recent years, the penetration level of renewable energy generation units such as wave, wind, photovoltaic, and tidal power plants in the modern power systems has increased. It began in the 1970s with a sudden change in oil price and today, large‐scale power plants based on renewable resources have been put into operation. Due to large potential of wave energies, the share of these power plants is expected to increase. Hence, it is necessary to study the effect of wave energy converters on the different aspects of power systems. For this purpose, the effect of variation in the generated power of wave energy converters arising from variation in the wave height and wave period on the operation studies of power‐system must be investigated. For the first time, the impact of large‐scale wave energy converters on the operation studies of the power system is investigated, and the numerical results of the wave dragon converter as a commercial‐scale wave energy power plant are considered. For this purpose, a multistate reliability model of wave energy converters is developed considering both uncertain nature of the generated power and failures of composed components of the wave power plant. To determine the optimal reliability model of the wave generator, XB‐index is calculated and fuzzy c‐means clustering technique is utilized. Then, the proposed multistate reliability model based on the modified PJM method, which is suitable for short‐term studies, is used to perform the operation studies of the power systems containing large‐scale wave energy converters. Numerical results of the operation studies of RBTS and IEEE‐RTS including wave farms are given in the paper to study the impact of wave energy converters on the reliability‐based operation indices of the power systems. [ABSTRACT FROM AUTHOR]

Summary: Increase in the penetration level of renewable resources results in the development of new approaches to assess the impacts of these variable resources on the power network. Large‐scale barrage‐type tidal generation units can integrate to the power network for reliability improvement. For reliability analysis of a power system containing these plants, a reliability model is developed. This model is considered the components' failure and also the output power variation arisen from the change of the tidal height should be developed. For this purpose, a multi‐state reliability model considering variation of tidal height that affects components failure rate and also the value of generated power is developed. The failure rate of components including transformer, turbine, cable, generator and electrical converter is dependent on the tidal height and turbine velocity. The paper is focused on the developing a thermal model for each component. Based on the temperature rise of the components, the associated variable failure rate is calculated from the Arrhenius law. The multi‐state reliability model of barrage‐type tidal energy conversion system considering variable failure rate of components is utilized to study the generation power systems adequacy based on the analytical and Monte Carlo approaches. This model is also utilized for reliability assessment of composite power system containing barrage‐type tidal power plants. Considering variable failure rate of components results in a more accurate reliability model for tidal power plant. Based on this model, the effects of different tidal patterns on the reliability indices can accurately be studied. [ABSTRACT FROM AUTHOR]

The penetration level of renewable and sustainable energy resources such as geothermal, wind, solar energies and ocean in power generation systems has been increasing. One of the important renewable energy resources is tidal power plants which makes use of rising and falling sea water level. Because of the uncertain nature of the generated power arisen from the variation in the water level in flood and ebb situations, integration of large-scale reservoir-based tidal power plants to power systems can involve numerous types of challenges. Thus, large-scale tidal power plants can be effectively used in operation studies of power systems. For this purpose, a probabilistic approach is introduced in this paper based on the modified PJM technique for integrating the large-scale tidal plant into operation studies of the power system. In this regard, a multi-state reliability model considering both the failure rate of composed components and the variation in the tide levels is developed and used in the operation studies. For evaluation of the impact of the tidal power plant on operation studies of a power system, numerical examples are put forward in which important indices such as unit commitment risk, required spinning reserve and peak load carrying capability can be calculated. [ABSTRACT FROM AUTHOR]

• For making the tidal barrages cost-effective, new methods should be implemented to increase the produced power of them. For this purpose, this study suggests new techniques for optimally operating of the basin-based tidal units equipped to hydro-pumps. • According to the proposed technique, to increase the produced power and consequently the produced energy of the basin-based tidal units, at each time step, the number of turbines, sluices and hydro-pumps is optimally determined to yield the maximum produced energy of the generation unit using of different heuristic optimization approaches. • For satisfying the effectiveness of the suggested approach, optimal operating of a basin-based tidal unit installed on the estuary of Bacanga is done and impact of optimally dispatching of the turbines, sluices and hydro-pumps on produced energy of tidal unit is studied. Among different renewable energy-based power plants, barrage type tidal power plants with high installed capacity can be integrated in the bulk power systems. However, due to the high investment cost associated to the construction of the barrages and related components, barrage type tidal power plants are less developed than other renewable resources such as wind turbines and photovoltaic farms. In order to economize the production of electricity from barrage type tidal power plants, it is necessary to reduce the cost of generated electricity by these power plants with new methods. For this purpose, the plant is considered to generate the electricity in the ebb mode, and using the hydro-pumps the height of the water in the reservoir is increased in the flood state. Based on this fact, in this paper, to maximize the generated energy of the barrage type tidal power plant, an optimal design is proposed and the effective parameters of the plant including the number of turbines, the number and width of the sluices, the turbine diameters and the number of hydro-pumps are determined using of three optimization techniques including particle swarm optimization method, genetic algorithm and imperial competition algorithm. [ABSTRACT FROM AUTHOR]

The sudden rise in oil price in 1970s led various countries around the world to turn to renewable energy resources for electric power generation instead of fossil fuel-based power plants. Among different renewable power generations, wind and solar power plants have reached maturity and have been able to make a significant contribution to electricity supply. Tidal power plants have grown less due to high cost of investment. Hence, their share of electricity generation has been lower than that of wind and solar power plants. The potential of tidal energy is high and it is expected that tidal energy can play a key role for electricity production in the future power-system due to its accurate predictability. Two types of tidal power plants including barrage-type and current-type tidal power plants are developed for energy extracting from tides. The current-type tidal power plant generates electricity from the kinetic energy of tidal-currents in a way similar to wind-turbines, while the barrage-type tidal power plants are equipped with dam, barrage and reservoir in order to generate electricity from the potential energy of water stored in the reservoir. This paper proposes several methods for enhancing the generated power of barrage-type tidal power plants, which result in cost reduction of electricity generated by tidal power plants. At first, an optimum design procedure for calculating the optimum values of number of turbines, number of gates, sluice width, turbine tip diameter and turbine hub diameter is established based on the particle-swarm-optimization-algorithm, aiming to maximize the yearly produced energy. Then, the hourly optimum number of gates and turbines are calculated in the operation studies for maximizing the daily produced energy. Also, the utilization of hydro-pump is simulated as the third method of generated power enhancement. In addition, three operation modes of barrage-type power plants, including ebb-generation, flood-generation and double-effect generation are simulated and the best operation mode in terms of power generation is determined. [ABSTRACT FROM AUTHOR]