Applying Nonlinear Model Predictive Control (NMPC) Philipp Petr, - - PowerPoint PPT Presentation

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Applying Nonlinear Model Predictive Control (NMPC) Philipp Petr, - - PowerPoint PPT Presentation

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) Philipp Petr, Christian Schrder, Prof. Dr.-Ing. Jrgen Khler, Dr. Manuel Grber ASME ORC 2015 - 3rd Seminar on ORC Systems, Brussels, October

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC)

Philipp Petr, Christian Schröder, Prof. Dr.-Ing. Jürgen Köhler, Dr. Manuel Gräber ASME ORC 2015 - 3rd Seminar on ORC Systems, Brussels, October 14th 2015

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 2

Waste Heat Recovery System in a Long Distance Bus

Total vehicle model (thermal, longitudinal dynamics)

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 3

Modelled ORC Concept (design stage) Working fluid: Ethanol Evaporator type: Fin-and-Tube Expander type: Effiency Based Condenser type: Tube-and-Tube

Waste Heat Recovery System in a Long Distance Bus

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 4

Waste Heat Recovery System in a Long Distance Bus

Control concept Expander inlet pressure controlled by expander speed Expander inlet enthalpy controlled by pump speed

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 5

Why Do We Need Advanced Control Strategies?

  • 1. Transient heat source temperature and mass flow rates
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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 6

Why Do We Need Advanced Control Strategies?

  • 1. Transient heat source temperature and mass flow rates
  • 2. Interactions between different subsystems
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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 7

Why Do We Need Advanced Control Strategies?

  • 1. Transient heat source temperature and mass flow rates
  • 2. Interactions between different subsystems
  • 3. Predicted states offer futher potential for energy recovery
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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 8

Why Do We Need Advanced Control Strategies?

  • 1. Transient heat source temperature and mass flow rates
  • 2. Interactions between different subsystems
  • 3. Predicted states offer futher potential for energy recovery
  • 4. ORCs shows a high grade of nonlinear behavior in transient operation

 Linear approaches not feasible in all operating conditions  Nonlinear approaches are beneficial, but complex  Nonlinear Model Predictive Control (NMPC) is one method to take this challenge  NMPC is a repetetive solving of an optimal control problem for finite prediction horizons

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 9

Development of a transient mathematical long-distance bus model with a waste heat recovery system Development of a software tool chain for NMPC Development of a differentiable High-Speed Model of the ORC for NMPC Virtual test drive in the European Transient Cycle to test the concept

Brief Overview on Presented Research

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 10

Block Diagram of the Nonlinear Model Predictive Control

Controlled System NMPC

Sophisticated ORC-Model

Control Variables 𝑣 State Variables 𝑦 High-Speed- Model Optimization

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 11

Block Diagram of the Nonlinear Model Predictive Control

Control Variables 𝑣 State Variables 𝑦 Controlled System NMPC High-Speed- Model Optimization

Nonlinear fast system model

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 12

Block Diagram of the Nonlinear Model Predictive Control

Controlled System Exhaust gas enthalpy flow rate Target function Constraining conditions

Computation of the optimal control variable trajectory

NMPC Control Variables 𝑣 State Variables 𝑦 High-Speed- Model Optimization

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 13

Software Tool Chain

Controlled System

ORC High-Speed Model

TISC TISC NMPC

Sophisticated ORC-Model

DYMOLA

Optimizer

FMI Suite TILMedia DYMOLA TILMedia Exhaust gas enthalpy flow rate Target function Constraining conditions

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 14

Computation Time

49

8

Differential and algebraic states ComputationTime

(Intel Core i7-4930K @ 3.40GHz)

High-Speed- Modell 30 min

Cycle Time (ETC)

Sophisticated ORC-Model High-Speed- Model Sophisticated ORC-Model

3

10

2 min 5 s

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 15

Benchmarking NMPC in Partial Load Conditions

Steady State Optimized Set Points Nonlinear Model Predictive Control Constant Set Point System is shut down in partial load conditions due to low mass flow rates Linear control approach. Gain scheduled controller parameter developed with AMIGO approach Prediction Horizon: 4s (real-time capable)

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 16

Results of the Virtual Test Drive (Urban Section of the European Transient Cycle)

Expander inlet pressure

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 17

Results of the Virtual Test Drive (Urban Section of the European Transient Cycle)

Expander inlet enthalpy

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 18

Results of the Virtual Test Drive (Urban Section of the European Transient Cycle)

Expander power

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 19

Results of the Virtual Test Drive (Urban Section of the European Transient Cycle)

Pump work

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 20

+ 8 % + 15 %

Results of the Virtual Test Drive (Urban Section of the European Transient Cycle)

 Higher net power output due to (optimized) ORC part load operation

7%

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 21

Conclusion and Outlook

  • Implementation of advanced control strategies are necessary for small ORC

systems operating under transient boundary conditions

  • Development of a software tool chain to realize a prototype NMPC
  • Development of an ORC High-Speed Model
  • Virtual Test Drive of a long distance bus proved the potential of NMPC in the

part load section of the European Transient Cycle (ETC) Outlook

  • Improvement of the High-Speed Model regarding computational time and

accuracy

  • Implementation of physically motivated expander models
  • Proof of concept by means of an ORC test rig
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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC)

Philipp Petr, Christian Schröder, Prof. Dr.-Ing. Jürgen Köhler, Dr. Manuel Gräber ASME ORC 2015 - 3rd Seminar on ORC Systems, Brussels, October 14th 2015

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Optimal Control of Waste Heat Recovery Systems Applying Nonlinear Model Predictive Control (NMPC) ASME ORC 2015 | 14.10.2015 | Philipp Petr | Slide 23

Contact Information

Philipp Petr

  • Mail. P.Petr@tu-braunschweig.de
  • Tel. +49 (0) 531 391 - 7895

Technische Universität Braunschweig Institut für Thermodynamik Hans-Sommer-Str. 5 38106 Braunschweig Germany www.ift.tu-bs.de Dr.-Ing. Wilhelm Tegethoff

  • Mail. W.Tegethoff@tlk-thermo.com
  • Tel. +49 (0) 531 390 - 7611

TLK-Thermo GmbH Hans-Sommer-Str. 5 38106 Braunschweig Germany www.tlk-thermo.de