load cycling of thermal power plants: advanced control ... · 11/30/2018 · advanced control...

Load Cycling of Thermal Power Plants: Advanced Control Technology as Cost-Efficient EnablerDr. Nicolas MertensFlexibilisation of Indian Thermal Power Plants, New Delhi, 30/11/2018

Agenda

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1

2

4

5

6

7

Who we are

Motivation for flexible coal operation

Coal fired power plant: A time-dependent system

Enhanced live steam temperature controller

Enhanced power plant load controller

Extended control system

Advanced Control Technology as Cost-Efficient Flexibility Enabler | Dr. Nicolas Mertens | New Delhi, 30/11/2018

8 Summary

Uniper at a glance

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Gas fired power plants

Nuclear plants

Coal fired power plants

Gas storage Regasification

Service

Hydroelectric plants

Gas infrastructureEnergy sales to small and large customers

Trading

Our operations

Power GenerationCommodity TradingEnergy StorageEnergy SalesEnergy Services We operate in 40+ countries. Around the world.

€1.7bnEBITDA in 2017

100 yearsExperience

~36 GWGeneration capacity

Main activities


Challenging requirements for coal flexibility Increasing network impact of intermittent renewable generation

Variable load following & faster ramp rates

Start-up & shutdown cycling

Longer periods off-load and in standby operation

Bigger swings between maximum and minimum load requirement

More competitive market conditions and pricing

Drivers to burn a changing or broader mix of coal types

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Back to agenda

Load cycling in coal-fired power plants: Secondary control response

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5 minutes

Time

Power

PowerOvershoot is limited!

Time

Power

Rate action


Load cycling in coal-fired power plants: Secondary control response

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Time

Power

Power

Time

Power

Extended set of controller structures and Parameters required!

Lots of cost-intensive plant tests required for optimization!

High load cycling capability improves market position!


Rate action

5 minutes

Coal Mill Operation

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Source:Steam and its generation and use

Mill behavior depends on

Coal quality Mechanical wear Plant layout Mill operation parameters Mill load Degree of automation …

Coal Mill: A time-variant system

8Advanced Control Technology as Cost-Efficient Flexibility Enabler | Dr. Nicolas Mertens | New Delhi, 30/11/2018

New grinding roller

Worn grinding roller

Coal Power Plant: A time-variant system

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Power

Pressure

Time

Pre

ssur

e in

bar

Pow

er in

MW


Coal type A, test run

Advanced Control Technology as Flexibility Enabler | Dr. Nicolas Mertens | New Delhi, 30/11/2018

Coal Power Plant: A time-variant system

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Each coal type needs a separate control parameter set.The parameter set depends on the maintenance status of the mill.Lots of expensive plant tests for parameter optimization are required.How about a controller that can adapt the parameter set automatically?

Power

Pressure

Time

Pre

ssur

e in

bar

Pow

er in

MW

Coal type B, test run

Live steam temperature control: Static PI controller

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Feed water pump

HP preheater

ECO

Evaporator

SH 1 Spray Attemp. 1

SH 2 + 3

Spray Attemp. 2

SH 4 SH 5

Spray Attemp. 3

Time behavior of SH5 depends on- Load (mass flows)- Coal type- Fouling and slagging

Only measurements upstream anddownstream of the SH are available.

Live steam

Live steam temperature control: State controller adapts to changing system behaviourState controllers with observers

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Observer

State Controller


525,0

527,5

530,0

532,5

535,0

537,5

540,0

542,5

545,0

0

10

20

30

40

50

60

70

80

90

100

0 300 600 900 1200 1500 1800

Frischda

mpftempe

ratur [°C]

Kraftw

erksleistung

[%]; Ve

ntilö

ffun

g [%

]

Simulationszeit [s]Sollleistung Kraftwerk brutto Istleistung Kraftwerk bruttoVentilöffnung (Zustandsregler) Ventilöffnung (PI‐Regler)Frischdampftemperatur (Zustandsregler) Frischdampftemperatur (PI‐Regler)


Live steam temperature control:Comparison of control concepts

Load

Valve position

Temperature (state controller)

Temperature (PI controller)

Setpoint deviation of the state controller is significantly smaller. Reason is that the state

controller anticipates control deviations by considering intermediate states.

Power plant load control: Controlled system

1414

feeder mill furnace steam generator

turbine +generator

Slow-reacting system, Disturbance on the controlled system cannot be identified. Measurement of a state variable in the middle of the controlled

system would help.


∑

Power plant load control: Controlled system

1515

feeder mill furnace steam generator

turbine +generator

New state variable:Promecon Coal dust measurement system


Measurement of absolute coal mass flow in kg/sec using microwave resonator technology Direct identification of mill disturbance,

small time constant Signal processing of coal measurement

in Kalman filter for control use, capturing mill dynamics

∑

Power plant load control: Enhanced state controller

State controller

Feeder, coal mill

Furnace, steam generator,turbine, generator

Feeder, coal mill, furnace, steam generator,turbine, generator

Real power plant

Model correction

K

Observer±

Set point

Coal dust flow Power


Reference: Wilhelmshaven Power Plant, Germany

1717

Wilhelmshaven Power PlantCommissioning 1976Power gross: 820 MWFuel: Hard Coal


Comparison of load controllers in real plant

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Standard controller

Enhanced state controllerMeasurement coal dust mass flow

Setpoint plant load

Setpoint coal dust mass flow

Measurement plant load 1 minute


Enhanced state controller runs passive and in parallelto existing controller for testing.Coal dust mass flow deviation is identified earlier!Enhanced state controller reacts approx. 1 minute earlier!Load cycling capability will be increased!

Conclusion

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Enhanced state controller delivers 50% increase in secondary

response capability (from 10% to 15% MCR) for the reference plant.

Power plants are time-variant systems, which require adaptive controllers

with automatic parameter adjustment for optimum load-cycling performance.

The coal dust measurement can be used to measure an additional state

variable in the power plant and improve control.

State controllers with observer are very effective in response to process

variation and disturbance of the coal mills.

State controller can be implemented independently from local DCS-OEM

system using external control box.


Thank you for your attention!

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Dr. Nicolas MertensSpecialist Plant FlexibilityUniper Technologies [email protected]

Doug WatersSalesUniper Energy [email protected]

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Animesh KumarChief Commercial OfficerIndia Uniper Power Services Pvt. [email protected]

load cycling of thermal power plants: advanced control ... · 11/30/2018 · advanced control...

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