Pazych S. The charge of a pumped hydroelectric energy storage from wind-electric installations with synchronous generators

Dissertation for obtaining the scientific degree of candidate of technical sciences on speciality 05.14.08 "Transformation of renewable energy". Institute of renewable energy of the National Academy of Sciences of Ukraine, Kyiv, 2020. In the dissertation the actual scientific problem concerning mathematical modeling of process of accumulation of energy of a wind flow in the pool-accumulator of a pumped hydroelectric energy storage with the purpose of integration of wind-electric installations in the structure of industrial and autonomous electric power systems. The process of converting wind energy into potential water energy was research by mathematical modeling of the operation of a wind turbine with a hydraulic pump with a rigid mechanical connection between them and the operation of a wind turbine unit with a multi-unit hydropump station with asynchronous motors. The research of dynamic processes is carried out at a 10-minute interval of averaging the wind speed, which is a standardized value for evaluating the energy properties of the system under research. The mathematical model of stochastic values of wind speed was improved by the established limitation on the magnitude of the acceleration of the gust of wind speed. This advanced mathematical model of stochastic change in wind speed was tested for ergodicity, its properties were determined as a stationary random process by statistically estimating 100 realizations for the averaged value of wind speeds. It is determined that the wind flow energy at a 10-minute interval by averaging the stochastic component is 5-10% higher than the constant average value of wind speed. The wind turbine is characterized by a mechanical torque that depends on wind speed, angular velocity, blade angle and is described by a hypersurface. To simplify its operation, a method of approximating the surface of the wind turbine aerodynamic characteristics by replacing the variables was developed, which allowed the output surface to be transformed to a universal one-parameter aerodynamic characteristic with the equation of coupling between the variables. Researches of the process of water accumulation by a rigid mechanical connection between a turbine and a hydraulic pump was carried out by mathematical modeling of the dynamics of rotational motion for variants of execution of high-speed and low-speed wind turbines taking into account stochastic changes in wind speed. Centrifugal and piston hydraulic pumps were used at different power ratios with the wind turbine. On the basis of application of the capacity factor during the year the effective ratios of capacities of various components of the wind-pumping installation in the range of operating wind speeds of 5-25m / s are determined. Mathematical modeling of the process of charging a pumped hydroelectric energy storage from a wind-electric installation with a synchronous generator was performed under the condition of using a multi-unit hydropump station driven by asynchronous motors. The model is a system of nonlinear differential equations that describes the interaction of two inertial components of a single aero-electro-hydrodynamic system. The first inertial component includes a wind turbine and a synchronous generator and the second - an asynchronous motor and a hydraulic pump. The mutual influence of one inertial component on the other is through the electrical connection between the generator and the motor through the transmission line. The parameters of mechanical rotational motion of inertial components were determined using the assumption of quasi-stationarity of electromagnetic processes in the stator and rotor circuits of the generator and the motor. The calculation of their electromagnetic moments was carried out using an equivalent alternating electrical circuit of the equipment, taking into account the variable speed and an arbitrary number of hydraulic units in the composition of the pumping station. The researches were performed at stochastic values of wind speed. It is found that the highest efficiency of energy accumulation is achieved by constructing a hydropump station of 5 or more units. Keywords: asynchronous motor, wind turbine, water pump, charge, synchronous generator, stochasticity, wind speed.