 
 
8a  OPTIMIZE 
8a.1  Introduction .......................................................................................................................................... 2 
8a.1.1  Offshore Vs Onshore optimization ......................................................................................... 2 
8a.1.2  The GUI tree-structure and its levels: Site>WTG>Size>Run ................................................ 2 
8a.2  Which decision to optimize? .............................................................................................................. 7 
8a.2.1  Design of layout (given park size) ......................................................................................... 8 
8a.2.2  Number of WTGs (park size) ................................................................................................. 9 
8a.2.3  Choice of turbine model ....................................................................................................... 10 
8a.2.4  Fulfillment of constraints (spacing, noise, lifetime, wake) ................................................... 11 
8a.3  Optimization algorithm ...................................................................................................................... 12 
8a.3.1  Start model .......................................................................................................................... 13 
8a.3.2  Step model ........................................................................................................................... 14 
8a.3.3  Stop criteria .......................................................................................................................... 14 
8a.3.4  Objective & Constraints ....................................................................................................... 15 
8a.4  Objectives ........................................................................................................................................... 16 
8a.4.1  AEP ...................................................................................................................................... 16 
8a.4.2  Costs .................................................................................................................................... 16 
8a.4.3  LCOE ................................................................................................................................... 18 
8a.4.4  NPV...................................................................................................................................... 18 
8a.5  Constraints ......................................................................................................................................... 20 
8a.5.1  Area & distance (sub-areas) ................................................................................................ 20 
8a.5.2  Wake loss ............................................................................................................................ 20 
8a.5.3  Noise .................................................................................................................................... 20 
8a.5.4  Component Lifetime (loads) ................................................................................................ 21 
8a.6  Practical recommendations .............................................................................................................. 22 
8a.6.1  WTG Area import ................................................................................................................. 22 
8a.6.2  Example projects ................................................................................................................. 23 
8a.7  References .......................................................................................................................................... 24 
 
   

Introduction 2

8a.1 Introduction

The Classical Optimizer in windPRO was released around year 2000. It has performed well for the tasks it was

designed to solve in the youth of the wind energy business. Since then, the development of the wind industry

has been fast, and many new requirements and challenges have become relevant. The size of wind farms and

the complexity of wind farm areas has increased dramatically. But also, the basis on which decisions are made

has matured, so that financial parameters such as costs of developing the farm and even the expectation for

future electricity prices should be included already in the windfarm design phase. In addition, new constraining

factors emerged that must be considered, such as wake effects from new wind turbines on existing wind turbines.

These developments have led to the need for a new windPRO Optimizer has been released in 2022 in windPRO

3.6. This was just the start of journey towards optimal design and operation of wind farms, and new features

have been integrated since into the new windPRO 4.0. Now, in addition to layout optimization, a long-awaited

noise curtailment optimization is offered, which is explained in detail in the Noise Curtailment Optimize manual.

The journey has not ended here; a wider range of cases will be supported, and more features will be included in

windPRO versions to come. If you experience limitations, have wishes or ideas please do not hesitate to reach

out and contact us – we are more than happy to listen to your input!

8a.1.1 Offshore Vs Onshore optimization

The New Optimizer in windPRO covers both onshore and offshore optimization. For offshore layouts the

geometry is not fixed, for this functionality the user is referred to as the Classical windPRO optimizer. The key

differences between onshore and offshore optimizations lie in the setup of the wake decay constant for the

annual energy production (AEP) calculation and in the model for calculating the cost of building the wind farm (if

costs are included in the objective). Hence, for pure optimizations of AEP there is no difference in the way that

the Optimizer operates. However, the performance will of course be guided by the user-provided information

such as WTG area and resource, which typically have distinct characteristics offshore and will be reflected in

the resulting optimization solutions. A new feature that is particularly useful for offshore applications that came

with the release of 4.0 is the integration of cost surfaces. This feature allows to better integrate costs that change

over space into the cost analysis. Further details of onshore and offshore cost models are given in section 8a.4.2.

8a.1.2 The GUI tree-structure and its levels: Site>WTG>Size>Run

A flexible graphical user interface (GUI) has been developed for the New Optimizer to accommodate several

different scenarios of use (see section 8a.2 for a description of the scenarios). This flexible GUI is represented

by a tree located on the left side of the Optimizer window. The tree will be gradually built-up by the user with the

required input information and with the different optimization scenarios run by the user. A lot of information needs

to be defined and setup prior to running the optimizations. This setup of pre-defined data and pre-calculated

information is a prerequisite for gaining sufficiently fast, yet accurate, optimization results.

Figure 1: The basic components and levels of the GUI tree: Site, WTG, Size and Run, with Run highlighted.

Building the tree, setting up and preparing the optimization, different information and decisions must be defined

and entered. When a level or item is selected and highlighted in the GUI tree (see Figure 1) the window on the

right shows the contents associated to this item, e.g. Site. Adding new levels to build the tree is done using the

three buttons below the tree. On the first occasion of adding a level the relevant button is highlighted in green.

Figure 2: Building the GUI tree for the optimization and adding levels. Next step is always highlighted in green.

The following sub-sections go through the setup that needs to be defined at each level of the GUI tree. While

setting up and running optimizations the main window of the Optimizer should be on the tab Setup & run.

Introduction 3

Figure 3: When setting up and running optimizations the tab of main window should be on ‘Setup & run’.

8a.1.2.1 Site

The Site level is the fundamental level of the optimization, but there can be multiple Sites in the tree to allow

studying the effect of different basic assumptions. In the Site, the following information and settings must be

defined:

Site Climate/Resources - here the pre-calculated wind resource across the site must be defined by selecting an

‘rsf’ or ‘siteres’ file. Ideally, the resource has a grid resolution of 0.5 times the turbine rotor diameter or less as

this leads to a good balance between resolution and performance.

Objective – this is the choice of what the user wants to optimize: AEP (annual energy production), LCOE (cost

of electricity) or NPV (profit of project). These are described in detail in section 8a.4. For each choice of objective

several associated decisions are required. For instance, Wake Decay constant in the PARK calculation (all

objectives), setting up a Cost Model (LCOE and NPV) or setting the expectation for the future average Electricity

Price.

Constraints - The particular requirements for the site must be defined and ALWAYS requires definition of a WTG

Area. This defines the limits of the site area or sub-areas where turbine placement is allowed, any requirements

for minimum and maximum turbine numbers or capacity in each sub-area. It also defines exclusion zones and

set-back buffers as well as minimal spacing requirements for turbines in each sub-area. In addition to this the

spacing or inter-turbine Distance defined in the WTG area may be activated or deactivated. Finally, constraints

on turbine component Lifetime, turbine noise at noise sensitive areas, and Wake constraints for new and existing

WTGs may be activated (see section 8a.5 for further details).

Connection points – Objectives which require cost calculation (LCOE and NPV) may include known connection

points for external grid and road connection. These points must be pre-defined as Control points and selected

here.

Existing WTGs – If there are known turbines in the area from other projects which will create wakes on this

project they must be defined as existing WTGs and selected here. Their wake effect on the new turbines will be

included and the additional wake that they might experience can be considered.

Noise sensitive areas – If noise constraint is activated one or more noise sensitive area (NSA) points must be

selected here.

Figure 4: Setting up the Site level of an optimization and building the GUI tree.

Introduction 4

8a.1.2.2 WTG

At the WTG level the required data must be defined for the objective and constraints selected on the Site level.

All new turbines in optimizations in this branch of the tree will use the selected turbine and data.

WTG & Mode - Any optimization requires the selection of a turbine model from windPRO’s WTG catalogue, a

Hub height, and the Power curve/Mode for that turbine model. This is the basis for the AEP and wake loss

calculations. For traditional power curve data the appropriate power curve is selected and for Power Matrix data

the operation mode is also selected.

Lifetime/Loads – If lifetime constraint is activated the turbine Design Standard and Design Class must be defined

as well as the Load Response Model for use in the calculation of loads and lifetime.

Noise Data – When noise constraint has been activated, the noise data must be selected from the Noise curves

provided in the WTG catalogue. For Power Matrix the noise data are pre-defined via the selected mode.

Use individual WTG cost model - When multiple WTG types are defined for the same Site, it might be relevant

to define different cost models for each WTG type individually. In that case this option must be activated and the

cost model for the current WTG type defined here. This will override the cost model selected on the Site level.

Figure 5: Setting up the WTG level of an optimization.

8a.1.2.3 Size (and ‘Add Sizes & Runs’ button)

The Size level has no setting up on the window to the right. Instead, it is created in a single step together with at

least one Run at it its sub-level (child). This is done via the Add Sizes & Runs button (see green highlight in

Figure 5).

Once the Sizes and Runs have been created this window shows an overview of all the runs for this size. In this

regard a run is simply an optimization for the park size in question and subject to optimization settings.

The benefit from adding Sizes & Runs in a single step is mainly efficiency, so that more park sizes can be created

at once with identical optimization settings without further effort.

Define Park size(s) - Here the user can define the park sizes of interest. Note that ALL sizes from minimum

through to maximum will be created once the button Create & queue runs is pressed after which a separate

optimization will be run for each size. It is therefore recommended to limit the range of sizes such that it results

in a reasonable number of optimizations. The table above the size selection summarizes the requirements for

minimum and maximum turbine numbers in the WTG area. Limits on capacity are automatically converted to