4_Presentation on Measurement and Regulation 5&6

8/7/2019 4_Presentation on Measurement and Regulation 5&6

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Measurement

andRegulation

George Markogiannakis

Mechanical Engineer MSc

Energy Policy Analysis Department

Centre for Renewable Energy Sources and Saving

Potenza October 2010


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Regulation

Regulation of process variable in order tomaintain process operate at a conditionset by control variable.

Good control/regulation ensures thatprocess operates when and how neededthereby saving energy.

(Example: Cruise control in a car and a house thermostat are commonexamples of how controllers are used to automatically adjust some variableto hold the measurement (or process variable) at the set-point.


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Actual value:The measured value is each physical value of interest for the application, e.g. roomtemperature. For example, this actual value is measured by means of a sensor.

Desired value:The value which is required! This value is entered into the regulator and serves asthe preset value or target value for the regulation process.

Correction variable:(i.e. error)The signal that the regulator puts out in order to match the actual value with the

desired value! Positioning element:

The device that receives the signal from the regulator (= the correction variable)and puts into effect a response to produce the desired value, e.g. a valve or mixeror electrical drive

Disturbance variable:This is every variable which negatively affects the measured value and makesfurther compensatory regulation necessary. In the case of room temperature, thiscan be incoming sunshine or an open window for example.

Regulation device:A regulation device is defined as being a combination of a sensor, regulator and

positioning element

Regulation -Basic terms


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RegulationConventional control Process

Set Point

Actuator

Valve

Controller

Controller OutputProcess Variable


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Regulation - Types of regulators

Electrical regulating device:The valve positioning is influenced electrically;

Pneumatic regulating device:Compressed air is necessary in order to influence the positioning element;

Electro-pneumatic regulating device:The actual value is measured and reinforced electronically. However, influencingthe positioning element occurs pneumatically.

Electro-hydraulic regulating device:The actual value is measured and reinforced electronically. However, influencingthe positioning element occurs hydraulically.

Additionally, regulators can be differentiated by means of their regulating behaviour. Aregulator can either be continuous or discontinuous.

Discontinuous means that it can only accept particular values e.g. a valve that can eitherbe open or closed.

In the case of a continuous regulator, the positioning element itself alters the correction

variable independently of the regulation difference.


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RegulationControl Station


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Regulation

SCADA - Reactor


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Regulation - Measurement: Pressure

Absolute Pressure

Differential

Pressure


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Regulation

Pressure Transducer


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RegulationInfrared Thermometer


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Regulation

Thermocouple


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Regulation

pH Electrode


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RegulationButterfly valve


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Regulation

Control Valves


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Regulation


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RegulationBasic principle

Disturbing jump answer of control loop

Leading jump answer of control loop

Tolerance area

o ve rs w

ing ing d i s t a nc e

Settling time

Tolerance area

Regulation start timeSettling time

Over swinging distance


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D=0 undamped oscillationD=0,2 damped oscillation

Proportional-Regulator

RegulationP-Regulator


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RegulationPID Control

P actionD action

I action


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RegulationTemperature Programmer


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LufterhitzerAuenluft

Auenluft-klappe

Filter

Temperatur-whler

Stellglied

Regler

VentilatorZuluft

Temperaturesensor

Cooling recorder

External air Input air

External airflap valve

Positioning

element

Regulator

Temperature

selector

Regulation - Scheme, example air conditioning


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Regulation - Scheme, example oven

exhaust

Volume flowPressureTemperatureAnalysisTemperatur

Volume flowDensityQuality

Oil temperature oven outletTemperature of exhaustLocal temperature

From

oil atoveninlet

Burninggas

Process data measurement for amodern oven regulation

Modern oven temperature regulation

exhaust

Burning gasair


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RegulationRegulation Scheme


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RegulationOptimising Regulation

Energy Savings

Maintenance Costs

Energy Saved

Energetic Costs

Investment Costs


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Traditional load regulation

Variable speed

Pressure

Potential energy saving


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Time (s)

Current peak due to

S/T starter

Triangle

conection

Star

conectionCurrent

Nominal current 160 A

Normal Star/Triangle Starting


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Thank you for your attention

4_Presentation on Measurement and Regulation 5&6

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