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Анотація

SYSTEM OF TRACKING FOR THE POSITION OF THE SUN

V. Kharchenko, B. Nikitin, P. Tikhonov, G. Uzakov

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In the case of the use of photovoltaic systems with concentration, ensuring accurate tracking of the Sun is an indispensable condition for their successful functioning.

In the absence of tracking the movement of the solar disk across the sky during a light day, there are large losses of incoming solar radiation, which is highly undesirable when the solar systems are operating in an autonomous mode.

Sun tracking systems should be not only accurate, but also have a low cost and have high technological and operational characteristics.

The purpose of the study was the development of a system for tracking photovoltaic energy systems behind the Sun that could provide tracking of the sun in azimuth and zenithal parameters throughout the whole daylight with the use of a single electric motor to drive the pivot mechanism, and could also ensure the reorientation of the positioned object at the beginning of the daylight (a turn from west to east).

The system should include: the Sun's position sensor of the new original design (DPS), the automatic system control unit and the executive mechanism (two-coordinate tracking system with one electric motor).

The developed sensor of orientation in each channel contains from one to three parallel connected photocells, for which a load of 3 Ohm is set.

The first group of photocells is designed to generate a signal to turn the solar system to the left, the second - to produce a signal to turn the system to the right, the third - to generate a signal to stop the electric motor, when the normal plane of the moving solar system will be close to the direction of the sun.

The control unit is made on a modern element base, compact and provides automated control of the tracking system, including the operation of actuators.

The automatic tracking system in two coordinates contains a frame, a rotating frame with the possibility of azimuth movement, a receiving panel connected in the middle part with a swivel frame, an electric motor, etc.

The developed position sensor of the Sun and other components of the system were tested both in laboratory and in full-scale conditions.

When the sun's rays illuminate the elements of the solar orientation sensor, signals from it come to the automatic control unit. After processing the signal, the unit manages the reverse motor, providing a voltage of the specified polarity to the motor. Through the gearbox, the electric motor drives a swivel frame rigidly fixed to the vertical shaft. A receiving panel is attached to the frame using hinges, which moves along the azimuth together with the frame.

During the tracking process, when the pivot frame is moved along the azimuth, the panel automatically rotates along the elevation angle due to the change in the position of the rod, one end of which is hinged to the bed and the other is hinged to the receiving panel.

The receiving panel of the unit is adapted to accommodate solar collectors, photovoltaic thermal modules, photovoltaic cells.

A model of the installation with the developed tracking system was created. The model can be placed on the layout with a peak power of up to 500 watts. Tracking the position of the sun, the installation carries out from a 120-watt engine. The automatic control unit and the solar position sensor were designed so that the installation moved the receiving panel together with the installed instruments once per hour. In this case, the change in the position of the receiving panel by 15 ? is ensured by the engine operation for 3 s.

Estimating the daily power consumption of the engine for the vernal equinox shows that the power consumption of the motor, taking into account starting currents, is 480 W.

Conclusions. Based on the results of testing the developed system for tracking solar panels behind the Sun, it can be concluded that the proposed tracking system appears promising for practical use.