PID Controller for Temperature Control in Cyber-physical Home System

8/20/2019 PID Controller for Temperature Control in Cyber-physical Home System

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PID C ONTROLLER FOR T EMPERATURE C ONTROL IN C YBER -PHYSICAL H OME SYSTEM

Wai Wai [email protected]


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PRESENTATION OUTLINE p. 2

1. Introduction2. Research Background on Cyber-physical System (CPS)

2.1 PID Controller2.2 Hybrid Controller

3. Research Objective4. Cyber-physical Home System

4.1 Mathematical Representation4.2 Transfer Function

5. Hybrid Controller for Home Temperature Control System6. Simulation Scenario, Parameter, Setting and Result7. Discussion8. Concluding Remarks


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1. I NTRODUCTION

Home Temperature Control (HTC) System

p. 3

Summer Winter

Inside

28 CInside

20 C

Outside

37 COutside

0 C

SensorSensor

Window

Air Con

ServerGatewaySink

Internet

Inside

Outside

Winter

Summer


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Cost Satisfaction

Multiple devices

1. I NTRODUCTION (CONT .) p. 4

Our temperature control is considered the following featuresMultiple devicesSatisfaction with thermal comfortLow cost


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2. R ESEARCH BACKGROUND

Cyber-physical System (CPS)Interaction between the physical and virtual worlds through lots ofsensors and actuatorsPhysical and engineered systems whose operations are monitored,coordinated, controlled and integrated by a computing andcommunication core

p. 5

Control

Cyber Physical

System

Communication

ComputationCharacteristics of CPS

CPS models must stand forPhysical worldSensors and actuatorsHardware platformSoftware

NetworkControl system

CPS models must incorporateTimingConcurrencyDynamics

CPS(discrete) (continuous)(hybrid)


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2. R ESEARCH BACKGROUND (CONT .)

Why CPS is necessary in home system?

p. 6

Wireless Sensor Networks(WSNs)

Only sense and monitorUnable to affect the state of

physical environment

CPSIntegration of computation,

networking and physicaldynamics with hybrid control

ReasonsBetter thermal comfort environmentComfort satisfaction by dynamicallymonitoringLong life of the buildingDesired temperature with low cost


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dt t de

K dt t e K t e K t u d i p)(

)()()(

2.1 PID C ONTROLLER p. 7

PID stands for proportional-integral-derivative

Important ingredient of a distributed control system

Is combined with logic, sequential functions, selectors, andsimple function blocks to build the complicated automationsystem

PID algorithm is described by

K p = proportional gain K i = integral gain

K d = derivative gain e(t) = control error


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Discrete eventsystem

(controller)

Interface

Continuousdynamic system

(plant)

Continuous

inputs

symbols symbols

Continuous

inputs

Generator Actuator

2.2 H YBRID CONTROLLER

A large collection of systems ofvarious classesInvolves a variety of mathematicaland engineering disciplines

Discrete event system finite statemachine (FSM), fuzzy logic, etcContinuous dynamic system differential geometry, differential

equations, etc Interface communicates the twodifferent layers by means oftranslating signals between them

p. 8


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3. R ESEARCH OBJECTIVE p. 9

To develop a practical CPS approach for home system

To design the closed-loop HTC system with two actuators(air-conditioner and window) by continuously monitoringthe desired temperature regardless of dynamically changingenvironment

To understand and analyze how our HTC system controlthe desired room temperature with PID controller andhybrid controller with minimum cost


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2

1

0

,

,

,

wopaoff

wcl ao n

wcl aoff

S

S

S T set (t ) = setpoint temperatureT out (t ) = outside temperatureT r (t ) = output temperatureT r (t ) = measured room temperatureT e (t ) = error temperature

T so (t ) = supplied temperature from outsideT sa (t ) = supplied temperature by air-conditioner

u(t ) = control input

s(t ) = switched control signal =

WSAN = Wireless Sensor and Actuator Network

T set (t )

T r (t )

T e (t ) u(t )

T so (t )

+

+

+ _

PIDController

Window

Air-conditioner

Room

SensorWSAN

Hybrid Controller Disturbance s(t )

+ T sa (t )

4. C YBER -PHYSICAL HOME SYSTEM p.10

T r (t )

T out (t )


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4.1 M ATHEMATICAL R EPRESENTATION p.11

Symbol Definition Equation

Qaircon

Qairflow

Qdth

Q ss

Qoccupant

Heat supplied by air-conditioner

Heat generated by window opening

Heat gain through the glass due totemperature difference betweeninside and outside

Heat gain when the sun shinesthrough the window

Heat gain from the occupants

)1(1

)( t T Qt T r all r Ʃ Q

all = Q

aircon+ Q

airflow+ Q

dth+ Q

ss+Q

occupant

The dynamic room temperature is given by

where


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StatusRate of

room temperature changingTransfer function

Air-conditioner

where

,

Window openingwhere

C ac=1.08 CFM

C dth = u g · A g

C dth = u g · A g

4.2 T RANSFER FUNCTION p.12

C w=A op cd vair C p ρair


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T oon = offset temperature forair-conditioner is ON

T ooff = offset temperature forair-conditioner is OFF

T out (t) = outside temperature s(t) = status of switched control signal

5. H YBRID CONTROLLER FOR HTC p.13

T e (t)

S aon,wcl s(t) = 1

S aoff,wcl s(t) = 0

S aoff,wop

s(t) = 2

T r (0) = T set

T out (t)

s(t)

T r (t) > (T set + T oon ) ^ T out (t) > T r (t)

T r (t) = (T set + T ooff )

Actuators: Air-conditioner, WindowInitial state: S aoff,wclS aoff,wcl = air-conditioner is OFF & window is CLOSEDS aon,wcl = air-conditioner is ON & window is CLOSED

S aoff,wop = air-conditioner is OFF & window is OPENED


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Simulation Environment

MATLAB/Simulink

PI controller

Used experiment measuredinside/outside temperature of theiHouse facility during summer season(2010 August)

One living room with four windows

Assumption

Heat gain from the occupant and heat gainfrom the sun through the glass are constant

For window opening state, the velocity of

air is constant No heat loss from the room

6. S IMULATION SCENARIO p.14


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Constant and coefficientVolume of the room : V room 5.005 m 4.095 m 3 m

Density of air : ρair 1.2 kg/m3

Specific heat capacity air : C p 1.005 kJ/kg C

Air volume flow rate : CFM 300 ft 3 /min

Desired temperature : T set 25 C

Supplied temperature by air-conditioning system : T sa

19 C

Offset temperature for air-conditioner isON : T oon

0.5 C

Offset temperature for air-conditioner isOFF : T ooff

0.2 C

No. of air-conditioners 1

Area of window type1 (L W) : A g1 1.2 m 1.77 m

Area of window type2 (L W) : A g2 1.2 m 0.6 m

Surface area of opening for windowtype1 : Aop1

1 m2

Surface area of opening for windowtype2 : Aop2

0.456 m2

‘u’ value for clear 6mm, double glazingglass : u g

2.8 W/m2

C

Constant and coefficientDischarge coefficient for a 'Flat Plate' orifice(hole) opening : cd

0.61

Air velocity leaving the opening (light air) : vair 3.4 m/s

Air node correction factor : F c 0.91

Shading factor for double glazing, openhorizontal blind and clear 6mm type of glass : F

s

0.95

Tabulated cooling load : q sg 238 W/m2

No. of occupants 1

Sensible heat gain by occupants (light working) :SHG

230 Btu/h

Latent heat gain by occupants : LGH 190 Btu/h

Cooling load factor for the occupants : CLF 1

Proportional gain for air-conditioner control (forday time) : K p PM

1

Integral gain for air-conditioner control (for daytime) : K i PM

2.5

Proportional gain for window (for night time) : K p AM

140

Integral gain for window (for night time) : K p AM 150

6. S IMULATION PARAMETER & S ETTING p.15


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6. S IMULATION R ESULT : N IGHT T IME

10:00PM to 06:00AM

p.17

**Measured: Neither Air-conditioner nor Window is operated (2010 August)**ClosedLoop (without Hybrid): only Window is operated with feedback control**ClosedLoop (with Hybrid): Air-conditioner or Window is operated with feedback control

20

25

30

35

21:00 22:00 23:00 00:00 01:00 02:00 03:00 04:00 05:00 06:00

T e m p e r a

t u r e

( C )

Time (hour)

Desired temperature Outside temperature Measured temperatureClosedLoop (without Hybrid) ClosedLoop (with Hybrid)

State transition

S aoff,wcl

S aon, wcl

S aoff,wop

012

3

21:00 22:00 23:00 00:00 01:00 02:00 03:00 04:00 05:00 06:00Time (hour)State of Measured temperature

State of ClosedLoop (without Hybrid)State of ClosedLoop (with Hybrid)


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6. S IMULATION R ESULT : C OMPARISON p.18

Electricity consumptionHybrid controller canreduce 57.75% comparedto without hybridcontrollerHybrid controllerconsumes less energy innight time because of thehelp of opening thewindow to control the

desired temperature

3.95

1.67

0.00

0.33

0

1.5

3

4.5

6

Closedloop without Hybrid Closedloop with Hybrid

E l e c t r i c i

t y c o n s u m p t

i o n

( k W h )

Day time (10:00-18:00) Night time (22:00-06:00)


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7. D ISCUSSION

Even we could not achieve the desired temperature by naturalventilation (window opening), it helps to reduce the cost for theusage of air-conditioner

It is because of the some assumption in calculation, e.g., the air flow ratethrough ventilation opening V

airflowis constant

We also understood that PID controller enhance to achieve thedesired temperature faster by reducing steady-state error

However, we need to tune the gains of PID controller ( K p , K i , K d values)to satisfy the performance and it has a weak anti-disturbance

Hybrid controller advantages the room temperature controllingwith low cost although there are some oscillation

p.19


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8. C ONCLUDING R EMARKS p.20

In this research, we presented the design of CPS-based HTC system with two actuators (air-conditioner and window)We also presented the characteristics of PID controller andhybrid controller in HTC system to reduce the resource cost

Our future worksShort-term : to design more concrete simulation program and to studythe optimum value of PID gain with additional physical disturbanceslike number of occupants is increased

Long-term : to find the optimization algorithm by minimizing resourcecost


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T HANK YOU FOR YOUR ATTENTION !

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PID Controller for Temperature Control in Cyber-physical Home System

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