SolarPowerSystem

Computation of Base Power

The SolarPowerSystem models power degradation as a function of time. You must provide a power system initial epoch, the power generated at that epoch, and an annual power decay rate. Additionally, the AnnualDecayRate field models the power degredation on a per year basis. The base power is computed using

where "tau" is the power AnnualDecayRate, P_0 is InitialMaxPower, and "delta t" is the elapsed time between the simulation epoch and InitialEpoch.

Computation of Bus Power

The power required by the spacecraft bus for all subsystems other than the propulsion system is computed using

where A_Bus, B_Bus, and C_Bus are BusCoeff1, BusCoeff2, and BusCoeff3 respectively and r is the distance from the Sun in Au.

Computation of Power Available for Propulsion

The solar power model scales the base power based on a polynomial function in terms of the solar distance. Total power is compute using

where P_Sun is the percent sun ( full sun is 1.0, no sun is 0.0), r is the distance from the Sun in Au, and C_1 is SolarCoeff1 and so on. Thrust power available for electric propulsion is finaly computed using

Where "delta M" is power Margin.

Shadow Modelling and Discontinuities

Note that when modeling shadows for a solar power system, discontinuities in the force model can occur when the power avialable for propulsion is less than a thruster's minimum useable power setting. As a spacecraft passes from penumbra to umbra, and power avialable for thusting goes to zero, thrust power causes thrust acceleration to discontinuously terminate, causing issues when using adaptive step integrators. In this case, there are a few options. You can configure any itegrator to use fixed step integration by setting the ErrorControl to None. Or you can configure the integrator to continue propagating if a bad step, in this case a small discontinuity, occurs. See the Propagator reference material for more information.

Create a SolarPowerSystem and attach it to a Spacecraft.

          %  Create the Solar Power System
Create SolarPowerSystem SolarPowerSystem1

%  Create a spacecraft an attach the Solar Power System
Create Spacecraft DefaultSC
DefaultSC.PowerSystem = SolarPowerSystem1

BeginMissionSequence

        

For a complete descripton of how to configure all Resources required for electric propulsion modeling, see the Tutorial named Chapter 12, Electric Propulsion.