Energy System of the International Space Station

atomlib April 4, 2015 at 03:17

Energy System of the International Space Station

The ISS receives all its energy from the Sun. Like Earth, the station is located at a distance of approximately 149 million kilometers from the nearest star. At this distance, it is possible to extract more than a kilowatt of energy from each square meter. Energy at the station is collected by solar panels, which use the photoelectric effect to directly generate electricity. The main consumers of electricity at the station are thermal control systems, pumps, air treatment systems, and communications equipment.

On the farms of the ISS US segment, there are eight wings with solar panels for generating electricity. The remaining whitish rectangles are not photo cells, but radiators to dissipate excess heat. Each of the eight wings contains two panels, each of the panels consists of 16,400 cells located on approximately 105 square meters. The total area of all 16 panels is 1680 square meters. At the beginning of operation, 124 kilowatts of energy were generated, but now a typical value of 80 kW is used - electrical elements are degraded due to ionizing radiation. Of course, the value of power varies depending on the position relative to the Sun. An example of real output current and voltage for each of the eight wings. According to these data, the panels generate approximately 52 kilowatts of energy.

The names of each of the wings of the

Russian modules are completely autonomous. They were not delivered by the space shuttle, so they have their own control, communication and maneuvering systems, and they also have solar panels. The first module of the ISS was Zarya or FGB / FGB, as all astronauts call it. Two panels of 10.67 × 3.35 meters and 6 Zarya nickel-cadmium batteries can provide an average of 3 kilowatts of power. Now the solar panels of this module are minimized so as not to interfere with radiators on the farm of the American segment. Stars' solar panels are open, their maximum power is 13.8 kilowatts, which are difficult to achieve because of the shadow from the US segment.

The farm’s solar panels now produce approximately 160 volts, which pass through a DC-DC converter (DDCU). The output is 124 volts of direct current, this voltage is used in the American segment. The DDCU uses the Weinberg converter . The voltage can drop in the future when used in other international modules, for example, some Japanese equipment requires 124 volts, some 28, some 50.

For the Russian segment, the voltage is lowered to 28 volts DC - a similar value has historically been fixed in the Soviet and Russian cosmonautics. In the early periods of the ISS development, it was necessary to raise the Russian 28 volts to 120 for use in American modules.

Sockets are located in various modules of the station. This is what the Utility Outlet Port (UOP) looks like to get 120 volts. This is how 28 volt sockets look in the Russian segment. The ISS makes a revolution around the Earth in about an hour and a half and is often in the shade. While the station is lit, the solar panels collect energy, a small part of which is stored for later use in rechargeable batteries in the BCDU (Battery Charge / Discharge Unit). Each of the 16 panels has 6 nickel-hydrogen batteries. The stored energy is used after entering the shadow of the Earth. By the way, the life of these batteries is only 6.5 years, that is, they have to be changed. The first set lasted almost 10 years - 50 thousand charge-discharge cycles instead of 38 thousand design ones.