High power electric power generation, transmission and management of MR-SPS

Space Power Satellite(SPS) is a huge spacecraft to utilize solar energy in space. Because of the huge size, immense mass and high power, there exist many technical difficulties. The Multi-Rotary joints SPS (MR-SPS) is a new non-concentrator SPS concept proposed by CAST in 2014. The most important innovation is that the huge solar array is replaced by many disjunct small solar sub-arrays and each has two middle power rotary joints. So the intractable technical difficulty of the high power rotary joint is simplified by many middle power rotary joints and the single point failure problem existing in traditional platform SPS concept is avoided. For a GW class SPS system, the generated electric power in space will be over 2GW, the whole area of solar array will be several km squares. The high power electric power generation, transmission and management in space becomes a huge challenge. In the paper, the primary scheme of MR-SPS concept is presented and two important sub-systems, Solar Energy Collection and Conversion (SECC), Power Transmission and Management (PTM) are introduced. The SECC sub-system includes fifty solar sub-arrays. Each solar sub-array is composed of twelve solar array modules. The area of each solar sub-array is about 0.12km2. The solar sub-arrays transmit electric power to the cables installed on the main structure of MR-SPS by 100 middle power rotary joints. PTM sub-system combines, converts, transmits and distributes the output electric power of SECC sub-systems. Most power is transmitted to two high power electric interfaces of the antenna and is distributed in the antenna. The remaining power is transmitted and distributed to the platform devices of SPS for routine operation of SPS. The mix of distributed and centralized high voltage PTM is adopted to meet the requirement of electric power supply of the electric devices on SPS. Typical space environment influencing high power electric system are analyzed. The key technologies need to be researched and solved include high efficient, long life thin-film GaAs PV cell,ultra large high voltage (500V) solar sub-array, high power rotary joint, ultra-high voltage(20kV), ultra-light cables, high power converter, high power switch, etc, and assembly and maintenance.