University of Stavanger

uis.no

Simulating O&M with agent based and

discrete event models

Ole-Erik Vestøl EndrerudPhD Researcher

9/22/2016

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What we are going through

1. Problem and need in offshore wind

2. Modeling

3. Developing a framework for modeling O&M

4. Validation

5. Using O&M models for decision support

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3

Need

MAXIMISE

PRODUCTION

MINIMISE

COST

Problem

Existing decision support tools

are “black box”

Need for something more than

a calculator – root causes are

equally interesting

Existing methods does not

capture the behavior of

offshore wind farm O&M

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Why Model?

The Modeled World

The Real World

The Problem The Solution

Model Model Solution

Risk-Free Space

Types of Models

Courtesy of AnyLogic North America, Inc.

Monte Carlo Simulation

Defined as simulations that employ random numbers, U(1,0) random variates, which is used for solving stochastic or deterministic

problems.

- Averill M. Law1

1Simulation Modeling and Analysis, 5th Ed., Averill M. Law, McGraw-Hill Education, New York, ISBN 978-0-07-340132-4

Type of Models

Deterministic models does not

contain stochastic elements

(however, the initial conditions

can be stochastic)

Stochastic models contain

stochastic elements (random

failures, random weather,

etc.)

Analytic vs Simulation Models

Can be used when:

an analytic solution exist

behavior is linear

dependencies can be described

with equations

no causal or temporal

dependencies

Can be used when:

• vast amount of parameters

• complex behavior

• temporal and causal

dependencies exist

Benefits

• You can observe the trajectory of

the system over time

• You can measure anything at any

time

Analytic Models Simulation Models

Agent-based modeling A system is modeled as several agents with

individual behavior (i.e. subsystems).

Behavior is modeled with statecharts (part of

UML).

Actions can be performed when entering, being

in or exiting a state.

Actions can also be hindered when in a state.

Transitions make agents change behavior (e.g.

from waiting on weather to moving to wind

park).

Transitions between states can be triggered by

conditions, messages or timeouts.

Process oriented modeling System model with entities

flowing through a process

Actions are executed one after one according to a flowchart

Entities are all the same, and are passive meaning the system performs some action on the entity and not vice versa

However, when entering or leaving a stage in the flowchart an action can be triggered

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Difference between statecharts and flowcharts

Statecharts perform actions in response to events (i.e. transitions) and actions can occur at transitions, when entering a state, when in a state or when exiting a state.

Flowcharts perform actions automatically upon completion of the preceding action

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State 1

State 2

State 3

Event 1

Event 2

Event 3

Event 4

Action 1

Action 2 Action 3

Action 4

Developing a framework for modeling O&M

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Modeling physical assets

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Modeling physical assets

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Age failure model

Hazard rate failure model

Degradation models

Modeling the social network

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Validation

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£0m

£5m

£10m

£15m

£20m

£25m

£30m

Annual dir

ect

O&

M c

ost

s

Iain Dinwoodie, Ole-Erik V. Endrerud, Matthias Hofmann, Rebecca Martin and Iver Bakken Sperstad, 2015.

Reference Cases for Verification of Operation and Maintenance Simulation Models for Offshore Wind Farms. Wind Engineering 39(105)

Validation

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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Tim

e-b

ase

d a

vailabilit

y

Iain Dinwoodie, Ole-Erik V. Endrerud, Matthias Hofmann, Rebecca Martin and Iver Bakken Sperstad, 2015.

Reference Cases for Verification of Operation and Maintenance Simulation Models for Offshore Wind Farms. Wind Engineering 39(105)

Using O&M models for decision support

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Ole-Erik Vestøl Endrerud, Knut Ragnar Austreng, Nenad Keseric and Jayantha P. Liyanage, 2015. New Vessel Concepts for Operations and

Maintenance of Offshore Wind Farms. Proceedings of the Twenty-fifth (2015) International Ocean and Polar Engineering Conference

Using O&M models for decision support

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Ole-Erik Vestøl Endrerud, Nenad Keseric and Jayantha P. Liyanage, 2014. MARINE LOGISTICS DECISION SUPPORT FOR OPERATION AND

MAINTENANCE OF OFFSHORE WIND PARKS WITH A MULTI METHOD SIMULATION MODEL. Proceedings of the 2014 Winter Simulation Conference

Define decision alternatives and scenarios

Define output metrics Run n simulation runsDetermine based on

hypothesis testing the best alternative

Using O&M models for decision support

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SOV+2 SES 3 SES SOV

Thank you NORCOWE for four great years!

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