A SOLAR POWER PLANT WITH AN ELECTRIC MACHINE CONVERTER – INVERTER

Abstract

Voltaic solar power plants are mainly made according to the structural schemes of a series connection of solar panels and a semiconductor inverter. Solar panels are semiconductor devices that are designed to convert solar radiation energy into direct current electricity. The inverter is a semiconductor switch that is designed to convert direct current and voltage of solar panels into alternating current and voltage with the network frequency. The magnitude of the current and voltage at the output of the panels depends on the intensity of solar radiation of the panels and, depending on natural conditions, changes from zero to maximum. This irregular direct current voltage from the output of the panels is converted by the inverter into a regulated alternating current voltage corresponding to the voltage and frequency of the network, in shape approximated, to a certain extent, to a sinusoidal. The inverter is regulated in such a way that the electrical energy generated by the solar panels is completely, or to a specified extent transferred to the electrical network. Solar power plants made according to the specified scheme have the following disadvantages due to the switching nature of the conversion of the semiconductor inverter:

- non-sinusoidal shape of the output voltage,

- instability in overload and transient modes,

- limited boundaries of reactive current regulation,

- limited boundaries of electric power generation.

In the proposed technical solution, the above-mentioned disadvantages are eliminated due to the use of an electric machine converter-inverter, made in the form of a DC motor and a synchronous generator connected in series along the shaft, instead of a semiconductor switching inverter. The stator winding of the DC motor is connected to the output of solar panels, and the stator winding of the synchronous generator is connected to the network. The active power regulator is connected to the excitation winding of the DC motor, and the reactive power regulator is connected to the excitation winding of the synchronous generator.