This paper analyses the state of power engineering in Ukraine and the main trends in the development of the world market in the field of converting high-capacity powerful power units of thermal power plants into ultra-supercritical (USC) ones. It is shown that the energy sector of Ukraine requires special attention and the introduction of new modern technical solutions. Worldwide trends indicate that the emphasis is now on increasing the steam parameters before a turbine to ultra-supercritical ones. This allows one both to increase the efficiency of power units and to reduce thermal emissions, fighting the global environmental problem of climate warming. The implementation of this approach is proposed taking into account the realities of the Ukrainian economy and the available technical capabilities of the power engineering industry. This paper presents the results of variational computational studies of the thermal scheme of the 300 MW power unit of the K-300-23.5 turbine to be converted into a USC one. The problem was solved under the condition of maximizing the preservation of the thermal scheme, increasing the efficiency of the power unit and minimizing capital investments during the modernization of the turbine. It was chosen to preserve the regeneration system, as well as the medium-pressure (MP) and low-pressure (LP) cylinders. Considered and calculated were variants with the addition to the existing turbine of a USC cylinder and the creation of a new high-pressure cylinder (HPC) with insignificant changes in its overall characteristics. The results of computational studies showed that the most rational variant for modernizing the 300 MW turbine plant is the creation of a new HPC designed for operation at USC steam parameters as well as the addition to the IPC of a new cylinder with the purpose of increasing the reheat steam parameters while preserving the regeneration system.

The effect of blade spatial profiling with the help of tangential blade lean of Francis pump-turbine runner with heads up to 200 m on the flow structure and energy characteristics was numerically investigated. A flow part model of Francis pump-turbine of the Dniester pumped storage plant was adopted as original version. Two new blade systems were designed, which differed from the original version by mutual position of cross-sections in tangential direction: with positive and negative lean, while the shape of the cross-sections themselves remained unchanged. Modeling of the viscous incompressible flow in calculation domain, which contains one channel of the guide vane and the runner, for three variants of flow parts, was performed using the IPMFlow software based on numerical integration of the Reynolds equations with an additional term containing artificial compressibility. To take into account the turbulent effects, the SST differential two-parameter turbulence model of Menter is applied. Numerical integration of the equations is carried out using an implicit quasi-monotonic Godunov scheme of second order accuracy in space and time. The study was carried out for models with runner diameter of 350 mm in a wide range of guide vane openings at reduced rotation frequencies corresponding to the minimal, design and maximal heads of the station. A comparison of pressure fields and velocity vectors in the runners, pressure graphs on runner blades, distribution of velocity components at inlet to a draft tube, and efficiency of three variants of flow parts are presented. It was concluded that calculation domain with the new RK5217M2 runner with negative tangential lean has the best characteristics. An experimental study of three runners on a hydrodynamic stand are planned

An analysis of the existing and prospective blade seal designs for Kaplan runners was performed. The selected design type provides the maximum ecological safety for Kaplan runners. A 3D model of runner hub sector with the trunnion, inner and outer bushes of blade trunnion was generated taking into account the cyclic symmetry of the runner design based on the modern automated design engineering system. A diagram of application of external loads from the blade and lever to the given 3D model of the Kaplan runner hub segment was developed. The contact problem was formulated to determine the stress-strain state as well as the contact pressures at the inner and outer bronze bushes of the Kaplan runner blade trunnions in different operating conditions. The problem was formulated for the finite element method, taking into consideration the diagram of external load application and contact restraints to the given 3D model of the Kaplan runner hub sector in the software package for engineering calculations. Using calculation results, principal stress distribution diagrams and the distribution diagram for the contact pressure at the outer and inner bronze bushes of blade trunnions were obtained. Strength calculation results were processed using the data of principal stress distribution diagrams, and the contact pressure values at the inner and outer bronze bushes of blade trunnions were determined. A methodology for further use of the given analytical model in the evaluation of stress-strain state of Kaplan runners involving modern automated design engineering systems and software package for engineering calculations was developed. The comparison of stress-strain states of the blade trunnion bushes was performed for the old and new designs of the Kaplan runner seal.

The results of gas-dynamic design of a new flow part of a reactive type high-pressure cylinder (HPC) of the K-300 series condensing steam turbine are presented. The turbine was developed using a comprehensive methodology implemented in the IPMFlow software package. The methodology includes gas-dynamic calculations of various levels of complexity, as well as methods for analytical construction of the spatial shape of the blade rows based on a limited number of parameterized values. The real thermodynamic properties of water and steam were taken into account in 3D calculations of turbulent flows. At the final stage, 3D end-to-end calculations of the HPC, which consists of 18 stages, were carried out. The technology of parallel computing was applied in the said calculations. It is shown that a significant increase in efficiency and power has been achieved in the developed HPC due to the use of reactive type stages with modern smooth blade profiles and monotonic meridional contours.

The main objectives of the reconstruction are stated. Those are: increase of the service life of the hydro-turbines of Dnipro Cascade, enhancement of their efficiency, power, and environmental safety, extension of the power control range of the hydro-power plants, assurance of the reliability and improvement of the operating safety of their equipment and structures, meeting the environmental requirements, improvement of the quality of the generated electric power after control system rehabilitation. The article deals with and analyses the chronology of the creation of the optimal design for a vertical Kaplan hydro-unit oil piping taking into consideration the half a century operational experience and stages of hydro-turbine modernization for Dnipro-2 HPP. The experience in improvement of the hydro-unit and oil head system control design is generalized, from the unified solution to the creation of the all-new design. The methods of the oil system rod machining and preliminary control are amended. The temperature control of the automatic unit shutdown in case of heating of oil head bushes is introduced into the control system. The oil piping installation method is improved and step-by-step checking of the oil piping installation centering is introduced. As a result of implementation of a package of design and process engineering solutions, the optimal design of the oil piping of improved reliability was created. It decreased the unscheduled downtime of the units and cut expenses on their maintenance providing the cyclic recurrence recommended by the standards for the operation of the oil pressure device pumps and thus, decreased the electric power consumption for balance-of-plant needs. The objects of the implementation of the developed oil piping design are given.