Operation Regimes: A Comparison Based on Nannochloropsis oceanica Biomass and Lipid Productivity

Microalgae are currently considered to be a promising feedstock for biodiesel production. However, significant research efforts are crucial to improve the current biomass and lipid productivities under real outdoor production conditions. In this context, batch, continuous and semi-continuous operation regimes were compared during the Spring/Summer seasons in 2.6 m3 tubular photobioreactors to select the most suitable one for the production of the oleaginous microalga Nannochloropsis oceanica. Results obtained revealed that N. oceanica grown using the semi-continuous and continuous operation regimes enabled a 1.5-fold increase in biomass volumetric productivity compared to that cultivated in batch. The lipid productivity was 1.7-fold higher under semi-continuous cultivation than that under a batch operation regime. On the other hand, the semi-continuous and continuous operation regimes spent nearly the double amount of water compared to that of the batch regime. Interestingly, the biochemical profile of produced biomass using the different operation regimes was not affected regarding the contents of proteins, lipids and fatty acids. Overall, these results show that the semi-continuous operation regime is more suitable for the outdoor production of N. oceanica, significantly improving the biomass and lipid productivities at large-scale, which is a crucial factor for biodiesel production.

Device for beat absorption in piston pumps

Owing to the fact that the flow motion in piston pumps is irregular, it is not easy to achieve stable fluid flow in the pipelines (while adsorption and injection of fluid). Moreover, the beats occurring at times in the pipelines may lead to the failures in the pump operation and as a result to the breakdown of its operation regime. To solve these issues, provide continuous flow of injected liquid, as well as to eliminate the pressure fluctuations in fluid flow motion, it is recommended to use air devices in these pumps.

ANALYSIS TECHNIQUE OF FUNCTIONING OF COMPLEX WATER MANAGEMENT SYSTEMS BY THE EXAMPLE OF THE VOLGA-KAMA CASCADE OF HYDRAULIC UNITS

The article considers methodical approaches to the analysis of the current state of the management problem of water economic systems under non-stationarity of multi-year fluctuations of surface water resources. Application of the simulation modeling method for solving water management problems is substantiated. The main provisions of the analysis of initial hydrological information to control the operation regime of the Volga-Kama cascade of hydraulic units are given. Methodical provisions for the analysis of the operation regime of complex water management systems with a cascade of hydraulic units with reservoirs in its structure are formed. The operation modes of the Volga-Kama cascade of hydraulic units under the conditions of different water content of the Volga River are analyzed. The considered methodic provisions are illustrated by the examples of simulated modeling of the Volga-Kama cascade operational regime under average water content conditions. The structure of modern water management systems and their functioning is presented as an open multicomponent dynamic system. The ultimate goal of the analysis technique of the water management system with the knowledge of the regularities of hydrological system formation is development of formalized mathematical models of this system functioning and investigation of many alternative variants under different natural-economic conditions.

Wind Farms Placement in an Electric Power System

Specific conditions of wind farms operation require special treatment of the wide range of aspects, in particular, calculation of the parameters characterizing the influence of wind farms on the power system operation regime and efficient practical representation of data calculated for a long period of time. The aim of the study is to formulate a method for placing the totality of wind farms in the electric power system (EPS). To this end, it is necessary to estimate the influence of wind farms on the EPS operation regime main parameters. For carrying out the study, methods for statistical processing of big databases, optimization methods, and numerical methods were used. Computational experiments were carried out in the Microsoft Office Excel software package. Based on the study results, criteria have been obtained using which it is possible to determine the most suitable places for the installation of wind farms, for example, to reduce the fluctuations in the EPS generation schedule. In addition, the values of the revealed indicators are used to evaluate the possibility of controlling the existing conventional power plants and identify measures for widening the adjustment range. The larger the capacity of wind farms, the more significant their influence is; however, the negative component of this influence decreases if many wind farms operate in the power system. By using the developed method, the most rational nodes of the EPC can be selected using the identified criteria at the design stage in determining the wind farms installation places. The accomplished studies have yielded a simple and practically applicable approach to determining the most optimal wind farm placement sites.

Optimal Frequency Support of Variable-Speed Hydropower Plants at Telemark and Vestfold, Norway: Future Scenarios of Nordic Power System

The integration of renewable resources is quickly growing in the Nordic power system (NPS), and it has led to increasing challenges for the operation and control of the NPS. Nordic countries require that the first-generation power plants have a more flexible operation regime to overcomes power imbalances coming from fluctuations of the demand and supply. This paper assesses optimal frequency support of variable-speed hydropower plants installed in Telemark and Vestfold, Norway, considering future scenarios of NPS. The total kinetic energy of the NPS is expected to be significantly reduced in the future. This paper looks into the implementation of hydropower units with a variable-speed operation regime and battery energy storage systems (BESS), equipped with fast-active power controller (FAPC) technology, to provide fast frequency response after a system frequency disturbance. The frequency support was formulated as an optimization process; therefore, the parameter of the FAPC was optimally calculated for future scenarios of low inertia in NPS. Three main futures scenarios were developed for technology penetration in the Vestfold and Telemark area in Norway. The simulation results showed that the integration variable-speed hydropower units and BESS technologies improved the frequency response even in low-kinetic energy scenarios.