In evaluating the energy-generation potential of a photovoltaic (PV) energy system, the system is usually assumed to work without interruptions over its entire life. PV energy systems are fairly reliable, but as any complex system, they may fail. In PV systems, the inverter is responsible for the majority of failures, and most inverter failures are blamed on the aluminum electrolytic capacitors typically used in the dc bus. This paper investigates the effects of common failure modes on the reliability of PV inverters and suggests a model framework for decomposing the inverter into subsystems for more detailed study. The challenges of statistical analysis based on small data sets are discussed, and simulations are performed to illustrate the proposed model using a simple decomposition into subsystems of the inverter used in the 342-kW PV system at the Georgia Tech Aquatic Center.

Development of a Methodology for Improving Photovoltaic Inverter Reliability

A Bayesian framework for on-line degradation assessment and residual life prediction of secondary batteries inspacecraft

There is a growing interest in using dc power systems and microgrids for our electricity transmission and distribution, particularly with the increasing penetration of photovoltaic power systems. This paper presents an electric active suspension technology known as the dc electric springs (DC-ES) for voltage stabilization and power quality improvement. The basic operating modes and characteristic of a DC-ES with different types of serially connected non-critical loads will first be introduced. Then, the various power delivery issues of the dc power systems, namely bus voltage variation, voltage droop, system fault, and harmonics, are briefly described. The operating limits of a DC-ES in a dc power grid is studied. It is demonstrated that the aforementioned issues can be mitigated using the proposed DC-ES technology. Experiment results are provided to verify the feasibility of the proposed technology.

DC Electric Springs—A Technology for Stabilizing DC Power Distribution Systems

This book provides a concise but broad overview of the engineering, science and flight history of planetary landers and atmospheric entry probes designed to explore the atmospheres and surfaces of other planets. It covers engineering aspects specific to such vehicles which are not usually treated in traditional spacecraft engineering texts. Examples are drawn from over thirty different lander and entry probe designs that have been used for lunar and planetary missions since the early 1960s. The authors provide detailed illustrations of many vehicle designs from different international space programs, and give basic information on their missions and payloads, irrespective of the mission's success or failure. Several missions are discussed in more detail to demonstrate the broad range of the challenges involved and the solutions implemented. This will form an important reference for professionals, academic researchers and graduate students involved in planetary science, aerospace engineering and space mission development.

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Planetary Landers and Entry Probes

DC bus-based systems are envisioned as an enabling technology to integrate renewable energy sources, energy storage devices, and a variety of loads in a number of power management and distribution scenarios. The system design and integration challenges include accommodating heterogeneous components, the wide variability of operating conditions, and system stability issues arising from dynamical interactions between the components. This paper proposes a flexible, smart dc power management architecture based on identical digitally controlled bidirectional dc–dc modules that can be software configured to enable simple system design, exceptional system flexibility, and optimization of the use of available resources. Design of the reconfigurable digital control infrastructure of such versatile dc power system is discussed in detail from its system-level description to the low-level design of the digital compensators. Stability analysis of the dc bus voltage is also discussed, proving the robustness of the power architecture from a theoretical standpoint. The proposed approach is then demonstrated on an experimental dc power management system consisting of several 500 W, bidirectional dc–dc modules operating from a 24-V dc bus.

Smart DC Power Management System Based on Software-Configurable Power Modules

POWER SYSTEM FUNDAMENTALS Satellite Overview Near-Earth Space Environment Power System Options Photovoltaic-Battery System Environmental Effects Power System Requirements Design Process and Trades PV-BATTERY SYSTEM Solar Array Battery Power Electronics and Magnetics Distribution Harness and Protection Ancillary Components POWER SYSTEM PERFORMANCE Energy Balance and Power Management Dynamic Performance and Stability Electromagnetic Interference and Compatibility Electrostatic Discharge Reliability and Derating Integration and Testing SPECIAL POWER SYSTEMS Interplanetary and Deep-Space Missions Radioisotope Thermoelectric Generator Dynamic Systems with Alternator High-Power High-Voltage Systems Electric Propulsion Fuel Cell Power Flywheel Energy Storage Superconductors in Space Microwave Beam Power Satellite

Mukund R. Patel

Papers

Spacecraft Power Systems