2017

Overview ofIntelligent Power Systems

for Future Aircraft

Distribution A: Approved for Public ReleaseCase Number: 88ABW-2016-4356 1

2017

Meeting Outline

• IPS Program Introduction

• Research Focus

• Example Applications

• Future Plans

• Summary

2

2017

Intelligent Power Systems

3

What is an intelligent power system?

• Intelligent Power Systems (IPS) is a robust and resilient power system capable of intelligent fault protection, autonomous reconfiguration, optimal power distribution, and power quality and stability

Program:

• IPS is a three year program investigating/developing new technologies to advance the state of art in (military) aircraft power management and distribution

• Model based demonstration of developed technologies to transition to large scale hardware demonstration complimenting other projects

FY 15 FY 16 FY 17 FY 18 FY 19

IPS Kickoff Finalize Team

and model

development

System level

analysis/research

areas

Model based

demonstration

Transition to

Hardware Test

2017

Intelligent Power Systems

page 4

Dual Redundant Power Drive Electronics

EDU 1

ICC 1

ICC 2

270VDC Battery

Motor 1

Motor 2

Drive 1

Drive 2

Simplified 270VDC Flight Critical Electrical Power System

Aircraft Data Bus

CS CS

CS

270V

DC

Bu

s 1

VS

27

0V

DC

Bus 2

EDU 2

Starter/Generator 1

Starter/Generator 2

Flight Critical Electric Actuator

• Advanced protection schemes leverage:

- Built-in sensors

- Advance Communication Bus

- Emerging solid-state distribution technology

• Advanced protection schemes provide:

- High speed feeder protection

- DP zones from generation to utilization

- Automatic “intelligent” recloser

- Arc fault detection and protection (parallel & series)

Intelligent

Power

Systems

Integrate and control the electrical

power system for autonomous

operation and protection

2017

Intelligent Power Systems Team

5

• Multi-university effort:

• AFRL - RQ Aerospace Systems Directorate• University of Dayton Research Institute• PCKA – Purdue University• The Ohio State University• University at Buffalo• Michigan Technological University• Rochester Institute of Technology• Idaho National Laboratory PC Krause and Associates, Inc.

Engineering, Modeling, and Software Solutions for Integrated Power, Thermal, and Propulsion Systems

2017

Meeting Outline

• IPS Program Introduction

• Research Focus

• Example Applications

• Future Plans

• Summary

6

2017

Aircraft Power Challenges

7

1. More demanding loads (in every sense!)

• Higher base load power: actuators, radar, etc.

• Higher peak power: Directed Energy Weapons (DEW), actuator

• Constant Power Loads with fast rise/fall power rates

2. Destructive faults:

• Parallel low impedance arcs

• Series high impedance arc

• Load/source faults and malfunctions

Continued electrification of the aircraft imposes several challenges:

2017

Aircraft Power Challenges

8

3. Power management:

• Stability challenges due to CPLs

• Dynamic power sharing between sources

• Distribution and reconfiguration

• Optimal power management

4. Electrical/Mechanical Interactions:

• Impacts to engine and thermal systems

• High Pressure (HP) / Low Pressure (LP)

• Coordination between engine and power systems

Source: INVENT Overview, IEEE 2012 Annual Meeting

2017

Research Focus (1)

9

Stability/Power Quality AnalysisGoals✓ Investigate/develop techniques for stability analysis due to Constant

Power Loads (CPLs)✓ Utilize energy storage to:

1. Improve the stability of the dc bus2. Maintain voltage within standard limits3. Minimize the ramp rates of power from generator

Intelligent Generator Program:Goals:✓ Optimal sizing of Generator and Energy storage✓ Enhance generator control unit to:

1. Better fault handling/mitigation2. Coordination with other sources3. Improved transient response

2017

Research Focus (2)

10

Fault AnalysisGoals✓ Series arc experimental characterization✓ Parallel faults impact to system level transients✓ Intelligent and adaptive fault detection and characterization

Power Management and DistributionGoals:✓ Dynamic source management and power sharing✓ Intelligent reconfiguration with performance guarantees – formal

methods, LTL✓ Smooth and stable transition between different modes

2017

Approach/Strategy

11

Analysis✓ Experimental testing/model extraction✓ Analytical – control oriented modeling✓ Controller/algorithm design

Modeling and simulation✓ Realistic/validated models✓ Controller implementation✓ Controller/algorithm simulation and verification

Hardware in the Loop (HIL) Testing✓ Investigate feasibility of controller

implementation in hardware✓ Smooth transition to hardware tests

2017

Meeting Outline

• IPS Program Introduction

• Research Focus

• Example Applications

• Future Plans

• Summary

12

2017

Stability/Power Quality Enhancement

13

• Problem: Active loads exhibit dynamic negative resistance which can cause system instability

• Approach

1. Frequency domain: Middlebrook criteria

2. Nonlinear techniques: Lyapunov analysis,model predictive control

• Accomplishments✓ Stability improvement through HESM control

✓ Bus voltage transient analysis andenhancement through predictive control

2017

Stability/Fault Analysis

14

• Stability enhancement through energy storage control

• Fault analysis and controller verification

A: Connect loadsB: FaultC: Open faulted cableD: Clear faultE: Reconnect loads

A B C D E

PC Krause and Associates, Inc.Engineering, Modeling, and Software Solutions for Integrated Power, Thermal, and Propulsion Systems

2017

Series Arc Characterization

15

• Problem: Series and high impedance arcs can be critically damaging to the aircraft. It is very challenging to detect due to low fault current

• Approach

1. Experimental testing of high voltage dc series arc

2. Model extraction for system level studies

3. Fault detection techniques

• Accomplishments✓ Develop a hardware platform for series/high impedance arc

✓ Preliminary model extraction of steady state characteristics

2017

Series Arc Summary

16

• Effort to experimentally characterizedc series arc at higher voltage levels, e.g.540 Vdc

• Steady state modeling of the series arcresistance:

• Detection techniques investigation using wavelet decomposition:

2017

Dynamic Power Sharing

17

• Problem: Generator sources must be ready to share power to reduce losses (heat) and assist engine/mechanical systems

• Approach

1. Graph theory based system analysis

2. Distributed and decentralized power sharing strategies

3. HIL platform and verification

• Accomplishments

✓Mathematical formulation of system using graph theory

✓ Preliminary HIL platform development based on OPAL RT and dSpace

✓ CAN network established for decentralized control

✓ Optimal gain designs

Real Time Simulation

G375 / 500

KW G375 / 500

KW

Controller Controller

Supervisor

CAN Network

2017

Objectives for Parallel Generators

18

1. Share the power as commanded with small error

2. Maintain limits on dc bus voltage based on standards

3. Fast transient response of the sharing strategy < 50 ms

4. Maintain stability during connection and disconnections of sources!

2017

System Reconfiguration/Management

19

• Problem: Contactor management to ensure power can always be delivered to the flight critical buses

• Approach

1. Define requirements/specifications

2. Formal methods and Linear Temporal Logic (LTL)

3. Tulip synthesis of controllers

4. HIL platform and verification

• Accomplishments

✓ Requirement specification using LTL

✓ Preliminary analysis on contactor delay

✓ Synthesis of management strategy

✓ Simulation based verification

2017

System Management Results

20

1. A very large model with many contactors can cause state space explosion

2. Parallel controllers to manage generators and energy storage

System2

System1

2017

Meeting Outline

• IPS Program Introduction

• Research Focus

• Example Applications

• Future Plans

• Summary

21

2017

Future Plans

22

• Finalize research/techniques for: intelligent generator control, stability/power quality enhancement, power management and distribution, and fault analysis

• Finalize representative system model and HIL platform for model based demonstration

• Ease transition to hardware tests for hardware programs

FY 15 FY 16 FY 17 FY 18 FY 19

IPS Kickoff Finalize Team and model

development

System level analysis/research

areas

Model based demonstration

Transition to Hardware Test

2017

Summary

23

• Intelligent Power Systems (IPS) is a robust and resilient power system capable of intelligent fault protection, autonomous reconfiguration, and optimal power distribution

• Developing new techniques to help generation, fault, management and distribution, and stability of power system

• Preliminary analysis/development of models and HIL platform for demonstration

• Real time simulation and HIL will ease transition to Hardware tests