09-03-2011, 10:42 AM
Submitted By
Pranay G. Umate
[attachment=9835]
ABSTRACT
The Solar Power Satellite (SPS) system is a candidate solution to deliver power to space vehicles or to elements on planetary surfaces. It relies on RF or laser power transmitting systems, depending on the type of application and relevant constraints. The SPS system is characterized by the frequency of the power beam, its overall efficiency and mass. It is driven by user needs and SPS location relative to the user. Several wavelengths can be considered for laser transmission systems. The visible and near infrared spectrum, allowing the use of photovoltaic cells as receiver surface, has been retained. Different frequencies can be used for the RF transmission system. The 35 GHz frequency has been considered as a good compromise between transmission efficiency and available component performances.
The utilization of the SPS to deliver power to small rovers or human outpost on Mars, and to an infrastructure on the Moon allows to assess different drivers in terms of user needs, receiver surface, distance between SPS and target, and to perform a preliminary sizing, based on current or reasonably achievable technologies, with respect to different sets of constraints. The SPS system appears as an attractive solution for these applications. The use of advanced or new technologies would drastically lower mass and increase the performances of the SPS system.
INTRODUCTION
Power generation is one of the crucial elements of space vehicles and of future infrastructures on planets and moons. The increased demand for power faces many constraints, in particular the sizing of the power generation system, driven by eclipse periods and the solar intensity at the operational spot. In the medium term, Earth orbiting platforms will require higher power levels. Interplanetary exploration vehicles face the problem of distance to the Sun, especially when high power levels may be needed. Large infrastructures on the Moon and planets, like Mars, are constrained by environment attenuation, long eclipse or distance to the Sun.
New systems and technologies have to be found, which go beyond simple improvements of the current technologies. Solar Power Satellite (SPS) systems, based on wireless power transmission, are attractive candidate solutions to provide power to space vehicles or to elements on planetary surfaces Studies have been carried out for many years on the problem of providing renewable electrical energy from space to Earth with SPS. The initializing for the solar power satellite (SPS) was optimized to a 1-km transmitting antenna producing 5 GW of DC power from a receiving antenna approximately 10 km in diameter. There are advantages to a lower power output and a smaller rectenna. Commercial utility companies prefer to integrate lower power levels into the irgrids .Rectennas smaller than the 10-km diameter in the reference configuration would make more rectenna sites available. Satellites are a revolution in telecommunication (in 20th century) has changed the way the people live.
Solar Power Satellite
A solar power satellite is a way to produce commercial electric power. A solar power satellite at GEO or other orbit sends the electric power gathered by its large solar panels to Earth using few GHz microwaves. The ground based receiver is an antenna field of about ten square kilometer area. The overall efficiency of microwave transfer from solar panel DC power to earthly grid AC power is about 50% and the power produced by a single satellite is of order one gigawatt. The power density of the microwave beam has been selected to be safely low so that for example a bird can conveniently fly through it without feeling a need to land and cool off. On the other hand, the microwave beam spreads during the long transfer distance, which is why the receiving antenna field has to be fairly large. From the constraints follows a characteristic unit power of GW order. This power level suits well for electricity production, although it complicates the building of small demonstration plants.
Taking the solar panels to space has two important benefits compared to installing them on ground. First, there is no night, clouds or winter in space, thus the plant can produce continuous electric power and consequently there is no energy storage problem. Second, in space one can use concentrator type solar collectors. The majority of the surface area of these collectors consists of lightweight parabolic reflector or Fresnel lens so that one needs much less of the expensive semiconductor. In ground-based panels, it is usually not economical to use concentrator type collectors because they produce no electricity in cloudy weather, require a sun-follower mechanism and support structures to withstand the wind load. If the production costs of solar panels come down markedly from their present level (at least by an order of magnitude), the latter benefit gets eliminated, but the first benefit, i.e. the absence of the energy storage problem, remains in any case.
Transmitter
The MPT use to the semiconductor amplifier is linearity of amplifier because power level of the MPT is much higher than that for wireless communication system and we have to suppress unexpected spurious radiation to reduce interference. The maximum efficiency usually is realized at saturated bias voltage. It does not guarantee the linearity between input and output microwaves and non-linearity causes high spurious which must be suppressed in the MPT. Therefore, dissolution of tortuous relationship between efficiency and linearity is expected by the MPT. There are unique development items for the SPS from the microwave point of view distinguished from the ordinary use of the microwave technology such as telecommunications
Receivers (Rectenna)
SPS, we need a huge rectenna site and a power network connected to the existing power networks on the ground. On contrary, there are some MPT applications with one small rectenna element such as RF-ID. The word “rectenna” is composed of “rectifying circuit” and “antenna”. The single shunt full-wave rectifier is always used for the rectenna.
Pranay G. Umate
[attachment=9835]
ABSTRACT
The Solar Power Satellite (SPS) system is a candidate solution to deliver power to space vehicles or to elements on planetary surfaces. It relies on RF or laser power transmitting systems, depending on the type of application and relevant constraints. The SPS system is characterized by the frequency of the power beam, its overall efficiency and mass. It is driven by user needs and SPS location relative to the user. Several wavelengths can be considered for laser transmission systems. The visible and near infrared spectrum, allowing the use of photovoltaic cells as receiver surface, has been retained. Different frequencies can be used for the RF transmission system. The 35 GHz frequency has been considered as a good compromise between transmission efficiency and available component performances.
The utilization of the SPS to deliver power to small rovers or human outpost on Mars, and to an infrastructure on the Moon allows to assess different drivers in terms of user needs, receiver surface, distance between SPS and target, and to perform a preliminary sizing, based on current or reasonably achievable technologies, with respect to different sets of constraints. The SPS system appears as an attractive solution for these applications. The use of advanced or new technologies would drastically lower mass and increase the performances of the SPS system.
INTRODUCTION
Power generation is one of the crucial elements of space vehicles and of future infrastructures on planets and moons. The increased demand for power faces many constraints, in particular the sizing of the power generation system, driven by eclipse periods and the solar intensity at the operational spot. In the medium term, Earth orbiting platforms will require higher power levels. Interplanetary exploration vehicles face the problem of distance to the Sun, especially when high power levels may be needed. Large infrastructures on the Moon and planets, like Mars, are constrained by environment attenuation, long eclipse or distance to the Sun.
New systems and technologies have to be found, which go beyond simple improvements of the current technologies. Solar Power Satellite (SPS) systems, based on wireless power transmission, are attractive candidate solutions to provide power to space vehicles or to elements on planetary surfaces Studies have been carried out for many years on the problem of providing renewable electrical energy from space to Earth with SPS. The initializing for the solar power satellite (SPS) was optimized to a 1-km transmitting antenna producing 5 GW of DC power from a receiving antenna approximately 10 km in diameter. There are advantages to a lower power output and a smaller rectenna. Commercial utility companies prefer to integrate lower power levels into the irgrids .Rectennas smaller than the 10-km diameter in the reference configuration would make more rectenna sites available. Satellites are a revolution in telecommunication (in 20th century) has changed the way the people live.
Solar Power Satellite
A solar power satellite is a way to produce commercial electric power. A solar power satellite at GEO or other orbit sends the electric power gathered by its large solar panels to Earth using few GHz microwaves. The ground based receiver is an antenna field of about ten square kilometer area. The overall efficiency of microwave transfer from solar panel DC power to earthly grid AC power is about 50% and the power produced by a single satellite is of order one gigawatt. The power density of the microwave beam has been selected to be safely low so that for example a bird can conveniently fly through it without feeling a need to land and cool off. On the other hand, the microwave beam spreads during the long transfer distance, which is why the receiving antenna field has to be fairly large. From the constraints follows a characteristic unit power of GW order. This power level suits well for electricity production, although it complicates the building of small demonstration plants.
Taking the solar panels to space has two important benefits compared to installing them on ground. First, there is no night, clouds or winter in space, thus the plant can produce continuous electric power and consequently there is no energy storage problem. Second, in space one can use concentrator type solar collectors. The majority of the surface area of these collectors consists of lightweight parabolic reflector or Fresnel lens so that one needs much less of the expensive semiconductor. In ground-based panels, it is usually not economical to use concentrator type collectors because they produce no electricity in cloudy weather, require a sun-follower mechanism and support structures to withstand the wind load. If the production costs of solar panels come down markedly from their present level (at least by an order of magnitude), the latter benefit gets eliminated, but the first benefit, i.e. the absence of the energy storage problem, remains in any case.
Transmitter
The MPT use to the semiconductor amplifier is linearity of amplifier because power level of the MPT is much higher than that for wireless communication system and we have to suppress unexpected spurious radiation to reduce interference. The maximum efficiency usually is realized at saturated bias voltage. It does not guarantee the linearity between input and output microwaves and non-linearity causes high spurious which must be suppressed in the MPT. Therefore, dissolution of tortuous relationship between efficiency and linearity is expected by the MPT. There are unique development items for the SPS from the microwave point of view distinguished from the ordinary use of the microwave technology such as telecommunications
Receivers (Rectenna)
SPS, we need a huge rectenna site and a power network connected to the existing power networks on the ground. On contrary, there are some MPT applications with one small rectenna element such as RF-ID. The word “rectenna” is composed of “rectifying circuit” and “antenna”. The single shunt full-wave rectifier is always used for the rectenna.
