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National Aeronautics and Space Administration
NASA Glenn Research Center Intelligent
Power System Control Development for
Deep Space Exploration
Anne M. McNelis
NASA Glenn Research Center
Presentation to
Energy Tech 2016
Cleveland, Ohio
1
Agenda
• Overview of NASA’s Deep Space Exploration Vision
• Communication Challenge for Deep Space Vehicle (EPS)
• Notional Deep Space Vehicle Power Architecture
• Traditional Space Vehicle Control Architecture
• Autonomous Control Architecture
• Control Function Objectives of Autonomous Controller
• Power System Simulations for Test and Verification
• GRC Testbed for Hardware in the Loop Verification
• Status and Future Plans
• Summary
2
The Future of Human Space Exploration
NASA’s Building Blocks to Mars
Earth Reliant Proving Ground Earth Independent
Missions: 6 to 12 monthsReturn: hours
Missions: 1 month up to 12 monthsReturn: days
Missions: 2 to 3 yearsReturn: months
Mastering the
fundamentals aboard
the International Space
Station
Developing planetary
independence by
exploring Mars, its
moons, and other deep
space destinationsU.S. companies provide
affordable access to
low Earth orbit
Pushing the boundaries in
cis-lunar space
The next step: traveling beyond low-Earth
orbit with the Space Launch System rocket
and Orion crew capsule
3
Communication Challenge
4
• Currently Electrical Power Systems
(EPS) require continual support
through ground based mission
operations.
• As missions extend beyond Low
Earth Orbit (LEO), communication
latency time increases.
• Communications bandwidth is a
factor of 100 less than ISS
• Power is the Most Critical System--
every system onboard needs power
Mission Communications
bandwidth
Communications
latency time
Deep Space
Vehicle
< 2 Mbps (DSN) 15 to 45 minutes
Apollo / Orion < 2 Mbps (DSN) 1- 2 seconds
ISS 300–800 Mbps
(TDRS)
Real-time
Space Power Systems
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• Crew of 4 to 6
• Provide living space for long duration
missions
• Solar Array / Battery System
• 24+ KW
• Potential to be operated in Low Lunar
Orbit, Near Rectilinear Orbit or Deep
Space
• Provides docking accommodation for
multiple vehicles – resupply as well
as landers
• Platform for the checkout and
validation of advanced technologies
• Closed loop life support systems
• Advanced automation systems
• Etc.
Notional Deep Space Vehicle
Deep space vehicle concepts
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• Multi-junction solar array power
• 24 kW for user loads
• 50 – 300+ kW for electric propulsion
• Two independent power channels with
multi-level cross-strapping
• Lithium Ion battery storage
• 300+ amp*hrs
• Sized for 1.5 hr eclipses
• Distribution
• 120 V secondary (SAE AS 5698 power
quality Spec)
• 2 kW power transfer between visiting
vehicles
Notional Deep Space Vehicle
Electrical Power System Characteristics
Notional Deep space vehicle concept
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Notional Deep Space Vehicle Power Architecture
8
Typical Spacecraft Control Architecture
99
Mission Operations (Planning and Execution)Power Thermal …….. ELCSS
Spacecraft
Control
Reactive
Control
Reactive
Control
Reactive
Control
Reactive
Control
Power Thermal ….. ECLSS
Power System Reactive Layer Controller
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RPC
SSU
1 of 8 power channels
RBIRBI
RBI RBI RBI
DCSU
MBSU
RPC
RPC
DDCU
DDCU
DDCU
B
C
D
U
B
C
D
U
B
C
D
U
B
C
D
U
Battery
Charge
Control
S/A
Voltage
Control
Switchgear Trip ControlSwitchgear
Trip Control
Secondary
Voltage
Control
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Traditional Spacecraft Controller Architecture Autonomous Spacecraft Controller Architecture
Transitioning some traditional ground based control functions to the vehicle
Development of an Autonomously Controlled Spacecraft is consistent with the “Future of Human Space Exploration” roadmap and enables the transition from “Earth Reliant” systems to “Earth Independent Systems”
Traditional vs Autonomous Spacecraft Controller
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Intelligent Power Controller
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National Aeronautics and Space Administration
www.nasa.gov 9
An Intelligent Power Controller utilizes advanced hardware and control
technology and works in conjunction with the spacecraft mission manager
to autonomously manage and control distributed power generation and
storage assets, power distribution networks, and loads for both near earth
and space exploration systems.
Near Earth SystemsExploration Systems
Autonomous Control Objectives
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Intelligent Control Functions
• Energy Management
– Power availability timeline
– Set points for array regulation,
battery charging / discharging,
– Detect generation and storage
failures
• Power System Model
– Generation model using orbital
parameters
– Energy storage model
– Power load flow
– State Estimator
• Power System Network
management
– Power network security
– Power quality
– Detect soft faults
– Report hard faults
– Configure switchgear
• Power System
Coordination
– Communicate with
Manager
– Coordinate with
identical power channel
entities and/or vehicles
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Simplified Autonomous Control Architecture
Autonomous Power Controller
Reactive Layer
EPS Hardware
Vehicle Manager
Mission Operations
Mission Operations
• Monitors vehicle operations
• Adjusts long term mission objectives
Vehicle Manager
• Plan vehicle operation to achieve
mission objectives
• Coordinate vehicle subsystems
Autonomous Power Controller
• Monitor / control normal mode of
operation
• Respond and report faults of the
EPS system
EPS Hardware (Reactive Control)
• Provides close-loop control of
the EPS hardware
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Autonomous Control State Diagram
• Normal State -- Normal operation, system operating on plan, continue indefinitely without interruption• Abnormal State – No faults in hardware but system is not performing as planned• Emergency State – Fault occurs – relieve system stress and prevent further deterioration• Restorative State – System is degraded but safe – restore power flow to all loads in a safe manner in minimum time
Assess / Manage Power System State
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Intelligent Controller Data Flow
Autonomous Power Controller
Reactive Layer
EPS Hardware
Vehicle Manager
Mission Operations
• Energy Availability
• Load Profile
Evaluation
• EPS Operating State
• ORU State of Health
• Caution/Warning
• Proposed Corrective
Action(s)
• Array Voltage
• Battery Current
Voltage
• Main Bus
Current / Voltage
• Secondary Bus
Voltage / Current
• Switch States
• Array Pointing Vectors
• Array Voltage S.P.
• Battery
Charge/Discharge SP.
• Switchgear Positions
• Navigation Vectors
• Traffic / Array Pointing
Constraints
• Spacecraft (other
subsystems) State
• Proposed load profile
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18
Contingency Planner
PVGC Generation Capacity Optimizer and Configuration
Manager
MYSQLDatabase
SIMULINKReal-time Simulation
Model
State Estimation
Failure Detector
Fault Identifier (Constraint
Suspension Test)
Network Configuration
Manager
Hardware Test Bed Interface
Graphical User Interface
Failure Identifier(Table Look-up)
Load Flow
Vehicle Manager
Internal Controller
Functions
External Interface
Functions
Autonomous Controller Structure
Test and Evaluation Approach
19
Deep Space Vehicle
Power System Test Bed
Real Time Simulation
Autonomous Controller
Dynamic Electric Power System Modeling
• NASA’s Advanced Exploration Systems (AES) Modular Power Systems (AMPS) projects
at GRC are developing intelligent control technologies for space applications.
• Common Electrical Power System (EPS) elements have been developed to be used
within space electrical power system simulations.
– Library of elements can be used on any number of configurations and used to simulate
various power system Simulink applications
• Simulation characteristics include the following:
– Provides real time, dynamic simulation of multiple connected power systems such as
multiple channels of ISS or Deep Space architectures
– Average value modeling of power electronics
– Faster, accurate circuit simulation for switching elements based on state equation
approach
– Features a communication infrastructure to synchronize simulations running on multiple
processors.
• Validation of the EPS elements was achieved by simulation of interconnecting channels
of ISS and comparison to available ISS power system Saber hardware model data.
20
EPS Model Library: Units and Assemblies Systems
ISS
Deep Space Habitat
Battery Cells
PV Cells
Isolating Converter
RPC
RBI
Electrical Power System (EPS) Simulation Development
21
Autonomous Power System Test Bed (GRC)
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• GRC’s Power System Testbed is
evolving into a platform to
evaluate the performance of the
autonomous control with real
hardware
• Contains
• Solar simulators / regulators
• Batteries / simulators
• Power Distribution
Equipment
• MBSU’s
• PDU’s
• Multiple Load Types
Status and Future Plans
Accomplishments:
• Defined and implemented an autonomous vehicle control architecture
• Implemented a distributed facility to develop and test the Autonomous Power
Controller (APC), Vehicle Manager, and test bed hardware
• Developed a real-time simulation of a notional Deep Space Vehicle power system
• Developed a prototype of an Autonomous Power Controller (APC) for Normal and
Failure Modes capable of long-term energy management
• Demonstrated an APC controller with remote hardware at NASA JSC
Future Plans
• Improve the development of APC algorithms for long term energy management of
the electrical power system (EPS) of deep space vehicle architectures.
– Improved capability to identify and diagnose power system faults
– Develop contingency capabilities to optimally manage resource allocation and
load scheduling.
– Develop and integrate APC with NASA GRC’s power system test bed for
hardware in the loop evaluation
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Summary
• Intelligent Power Systems are key for long duration missions
and operations far from earth.
• Development of an Autonomously Controlled Spacecraft is
consistent with the “Future of Human Space Exploration”
roadmap and enables the transition from “Earth Reliant”
systems to “Earth Independent Systems”.
• Verification of developmental space EPS autonomous power
controllers will be achieved through real-time EPS
simulations, hardware in the loop and power system test bed
validation efforts.
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Questions???
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