BENJAMIN LOOP Simulation Environment for Power

Management and Distribution Development

SBIR Phase II/II-E

• Period of performance: July 2013 – July 2016

• Technical objectives • Develop a simulation environment to support the development of

autonomous controls

• Demonstrate distributed control architectures

Component and System Models

• Began working with ISS electrical system

• Moved to EAM system with similar overall architecture

• Modified component parameters and interconnections

International Space Station Exploration

Augmentation Module

Spacecraft Model Library

• Average value electrical

component models

• Solar array

• Sequential shunt unit

• Battery charge discharge unit

• Master bus switching unit

• DC switching unit

• Power distribution unit

• Aggregate load

• Constant power

• Constant current

• Resistive

• Remote power controller

• Remote bus interrupter

Model Fidelity • Fast electrical transients not necessary for

development of energy management controls • Skipped switch level models from the beginning

• Created average value models and validated against available hardware data

• Eliminated fast transients through model reduction and parameter modification

Switch

level

Average

value

Reduced

order

Power electronics

systems levels of

fidelity

Model Library Features

• Component parameter specification

• Constant or over-ridden by time-varying value

• Control signal specification

• Model certification GUI

• Specify inputs and outputs

• Automated html report

• Sensor model

• Communication model

Automated State Model Generator • ASMG is a circuit simulation tool developed by PCKA

• Automatically determines switch states and calculates model topology

• Enables expedited construction of complex systems

Native Simulink Implementation • Native Simulink implementation constructed to reach real-time

simulation speeds • Switching circuit models derived by hand

• Less flexible / user friendly

• Consistent computation time per simulation time step

Identification of Fast Transients • Eigenvalue analysis tool

• Matlab GUI that evaluates model eigenvalues

• Calculates participation factors for each mode, links to the relevant

block in the model

Eigenvalues

Participation factors State names

Small Signal Stability Analysis Tool • Parse Simulink model to determine

interconnection of components

• No simulation execution required

• Combine small signal models into

full system model for evaluation

Linear

interpolation：

Critical

Power

Command:

5.3296kW

5.3kW

5.4kW

Communication Modeling

• Network communication model using

ns-3

• Currently developing graphical interface

of the Simulink/ns-3 environment

• Determine topology from Simulink

connections

• Set up communication (and spam) through

block mask

n4 n2 | | | | s2---------s1---------s0 | | | | | | n1 n3 n0

Interface with Controller

• Interface developed with Case

Western Reserve University

• GUI allows definition of

• Planned scenario

• Actual scenario

• System parameters and initial

conditions

• Communication parameters

• Data logging parameters

• Automatically launches

simulation and control process

Controller Communication

• GUI launches processes and transmits relevant information to simulation and controller. Also logs data during simulation

• UDP communication between simulation and controller during simulation

Load Schedule

PV Schedule

Initial conditions

Pro

cess #

2

Scenario

Generator GUI EAM_Simulink.mdl

Controller

MA

TLA

B

t_start

PDU State

Load allocation

t

SOC

Sensor values

Extension to Aircraft System Modeling • Build on modeling experience with near-term military aircraft and apply to

N+3 generation aircraft electrical systems and technologies

• Provide modeling and simulation support for NASA aircraft electrical system testbeds

• Analyze tradeoffs of system configurations • Benefits of energy storage

• Stability analysis and control development

• Provide models to estimate size/weight/efficiency of components as they increase in power from ~100kW to ~10MW • Inverters, generators/motors

PCKA 220 kVA SiC inverter module

that will form the scaling basis