Modelling, control and supervision strategies for aeronautical electrical networks

ing. Beniamino GUIDATutor: Prof. Alberto CAVALLO

Dipartimento di Ingegneria Industriale e dell’InformazioneSeconda Università degli studi di Napoli

“Best PhD Thesis in a Clean Sky project” Award

Summary

v Motivation and IntroductionvModeling, control and supervision of a bidirectional DC/DC convertervSupervision of an aeronautical electrical network for intelligent energy managementvConclusions and future extensions

Motivation

q “Energy management” is a term used to evidence the need of a better use of energy on board aircrafts

How to properly implement new energy management strategies?

Need of a structured approach wheremodeling, control and supervisionof aeronautical eletrical equipmentare the main pillars

My PhD thesis!

INTRODUCTION

A/c electrical systems

q The function of the aircraft electrical system is to generate, regulate and distribute aircraft electrical power

q An aeronautical electrical network is composed by four subsystems:

1. Power generation2. Power conversion3. Power distribution4. Power utilisation

PEPDC

Bus bar 0 V (Power Ground)

ATRU

115 VAC - 400 Hz

+ 28 VDC

+ 270 VDC

115 VAC - Var Freq

Contactor controlRCCB protection

SSPC control

Flexray

PMCU

Contactor and Protection (RCCB)

Contactor

AC Current Sensor

DC Current sensor

AC voltage sensor

DC voltage sensor

SSPC

2 kW

20 A

EMA

EMAC1

=~=

Lab Supply 25 kVA

115VAC

LSC1100 A

~

LOADC220 A

LOADC3100 A

200 A

LVC1

ECS

DynamicLoad Bank

2 x 25 kW

200 A

ECSC1

SHARP

DynamicLoad Bank

25 kW

100 A

SHC1LOADC120 A

LOADC4400 A

Bi-way ConverterAC/DC

400 AADC1

Var FreqS/G

85 kVA

SGCU

250 AATRC1

BBCUDC/dc

12 kW

50 A

DDC1

Bus bar + 270 VDC

Low Speed Pad Drive Stand High Speed

Pad

Battery 28 VDC

400 Apeak 750 A

BATC1

GLC1250 A

Generator50/60 kVA

115 VAC 400 Hz

GCUCTU

Modelling levels

TASK 1: Modeling of aeronautical equipment

Architectural level: Steady-state power consumption. Usually, algebraic equations describing the energy balance between ports without dynamic response.

Functional level [1]: Steady-state power consumption and mean-value transient behavior (e.g. consumption dynamics). Switching is not included.

Behavioral level: Representing actual waveforms including switching and HF injection behavior.

Component level: Models at component level include a representative model of each single component of the system or sub-system

[1] S.R. Sanders, J.M. Noworolski, X.Z. Liu, and G.C. Verghese, “Generalized averaging method for power conversion circuits”, IEEE Transactions on Power Electronics, vol. 6, no. 2, April 1999

INTRODUCTION

Modelling techniques for reduced simulation times

k=0 : state-space averaging

Clarke

Park

MODELLING RATIONALEFor AC generators/motors à DQ0 models For uncontrolled AC/DC rectifiers à functionalmodels based on commutation/conduction periodsFor controlled DC/DC converters à functionalmodels with state space averaging

INTRODUCTION

Control strategies

TASK 2: Control of aeronautical equipment

[2] J. Guldner V. Utkin and J. Shi, “Sliding Mode Control in Electro-Mechanical Systems”, CRC Press, 2009

Generation Conversion

ØVoltages and currents are the regulated variablesØSliding mode control [2] is a suitable option

INTRODUCTION

Modern control of aeronautical equipment

CONTROL RATIONALE

Nested sliding or PI control for voltage or current regulation

For SSPC controlled equipment:

Sliding mode or PI control for voltage or torque regulation

For AC generators/motors For controlled DC/DC converters

Direct PWM control

INTRODUCTION

Supervision strategies

TASK 3: Supervision of aeronautical equipment

[3] J. A. Stiver X. D. Koutsoukous, P. J. Antsaklis and M. D. Lemmon, “Supervisory Control of Hybrid Systems”, In Proc. IEEE, Vol. 88, No. 7, pages 1026-1049, 2000

Single equipment Electrical network

ØApproaches can be combinedØSupervisory control [3] theoretical framework is adopted

INTRODUCTION

Supervision of equipment for energy management

SUPERVISION RATIONALEFor generation equipmentà often not requiredFor conversion equipmentà selection of electrical flow directionFor distribution equipmentà regulation of electrical power absorption

GENERATOR DES PLANT

SUPERVISOR ACTUATORSUPERVISION FRAMEWORK

INTRODUCTION

DC/DC converter: modelling

Topology selection Single cell structure

ØIn order to obtain an average model for the converter, aSwitched Inductor Model [4] has been derived[4] S. Ben-Yaakov and D. Adar, “Average models as tools for studying the dynamics of switch mode DC-DC converters”, in

Proc. IEEE Power Electronics Specialists Conference (PESC '94), pages 1369-1376, 1994

DC/DC CONVERTER

DC/DC converter: control

ØThe direct output voltage control is more suitable for supervision purposesØThe sliding mode control has been selected (switching converter)

SIMPLIFIED CONVERTER TOPOLOGY CONVERTER EQUATIONS

REMARK 1: Necessity of stability proofs for bidirectional converters when direct output voltage sliding control is considered [5]REMARK 2: Control proved on a simplified version of the full bridge converter

[5] A. Cavallo, B. Guida, “Sliding mode control for DC/DC converters”, In Proc. IEEE Conference on Decision and Control 2012 (IEEE CDC ‘12).

DC/DC CONVERTER

DC/DC converter: supervision

§ Supervision objective: Intelligent selection between Buck and Boost mode, in order to fulfill Power Quality standards [6]§ BUFFER mode, a patented [7] technique for bidirectional DC/DC converters automatic mode inversion

ØFour statesØTransitions based on the HV/LV voltagesØSuitable for aeronautical applications

[6] B.Guida, L. Rubino, P.Marino, A.Cavallo, “Implementation of control and protection logics for a bidirectional DC/DC converter”, in Proc. IEEE International Symposium on Industrial Electronics (ISIE 2010), pp. 2696-2701

[7] patent no. 11168742.2 – 1242 “Buck-boost mode switching method for a DC-DC converter, and DC-DC converter”. Inventors: B. Guida, L. Rubino, P. Marino, A. Cavallo, L. Di Donna, V. Anastasio

DC/DC CONVERTER

DC/DC converter: supervisionTestbench (SABER environment) Simulation results

Experimental results

DC/DC CONVERTER

Intelligent Power Management for electrical network

REMARK: the converter is only ONE of the equipment, taking power from an aeronautical electrical network , as well as other complex systems

CHALLENGE: extend the “energy management” concept to the entire network

I-LPM

I-LPM: models

I-LPM in a nutshell

AC Starter/Generator 9-phases 18-pulses AC/DC rectifier SSPC

A complete aeronautical network hasbeen modelled for I-LPM validation

I-LPM

I-LPM: control

v The representative equipment considered for I-LPM are:

Non Critical Loads: boiler, oven, beverage (NCL)

Environmental Control System (E-ECS)

Wing Ice Protection System (WIPS)

1) Choppable loads2) Motor loads

SSPCs used for voltage chopping at WIPS and CCS terminals

A protocol used to increase/decrease E-ECS absorbed power

CONTROL ACTIONS

I-LPM

I-LPM: supervision

A Petri Net based approach is adopted

Translation of I-LPM requirements first into a flowchart, then into a Petri Net

A proof of formal Petri Net properties (i.e. boundedness, liveness, reversibility) has been given (collaboration with Universitad de Zaragoza – prof. Silva)

I-LPM

I-LPM results

Generic Architecture testbench, enhanced with I-LPM

I-LPMmodule

ØMODELICA language

Ø The numerical values of the lower thresholds for the NCL operative areas are: NORMAL=250V ,D1=180V, D2=130V, D3=0V (shedding condition)

Ø The PWM frequency for SSPCs control is set to 1kHZ; therefore, a duty cycle variation can be commanded by the I-LPM every 1ms

Ø A criterion for power savings is defined

RESULTS

Results: I-LPM for aeronauticalelectrical network

ØThe insertion of external loads at t=15 secs determines the power decrease until t=20 secsRESULTS

I-LPM in real life: European projectsActivities related to DC/DC converter, and particularly the Buffer mode, were carried out within FP6 MOET project

I-LPM strategy was developed within Clean Sky 1 SUPREMAE project

PROJECTS

I-LPM in real life: European projectsI-LPM logic has been on-ground tested

within Clean Sky 1 I-PRIMES project, at the Copper Bird (Paris, 2014)

I-LPM strategy has been finally tested on flight within Clean Sky 1 EPOCAL project, installing an innovative Electrical Power

Center onboard an ATR-72 (Toulouse, 2016)

PROJECTSAEROMECHS has been founded in 2011, and involved in new SUN coordinated CleanSky projects as strategic partner for hwmanufacturing and firmware development

Flying for a real Clean Sky!

Thanks for your attention!

A milestone for Green Regional Aircraft and ATR (March 7th, 2016)

http://www.cleansky.eu/content/news/milestone-green-regional-aircraft-and-atr

https://youtu.be/5CuJ9kgoNGU

PROJECTS