CASE STUDY – EOLE PLAINE DES ROCHES WIND FARM

Poste Lafayette, Mauritius

Pager Power Case Study Eole Plaine Des Roches Wind Farm Case Study 2

CONTENTS

1 Introduction .......................................................................................................................3

2 Background ........................................................................................................................4

3 The Challenge ....................................................................................................................5

4 The Process ........................................................................................................................6

5 The Solution .......................................................................................................................7

6 The Result ..........................................................................................................................8

Pager Power Case Study Eole Plaine Des Roches Wind Farm Case Study 3

1 INTRODUCTION

In 2017, Pager Power was commissioned to investigate and assess reported

interference issues impacting a radio navigation aid known as a Doppler Very High

Frequency Omni-Range (DVOR), operated by the Department of Civil Aviation in

Mauritius. Specifically, there were concerns that the interference could be caused by

the operational Eole Plaine Des Roches wind farm, located to the southeast of the

navigation aid.

Figure 1: Photograph of a VOR ground station

Pager Power Case Study Eole Plaine Des Roches Wind Farm Case Study 4

2 BACKGROUND

The Department of Civil Aviation in Mauritius operates a DVOR located at Grand Baie

on the north of the island of Mauritius. This is an installation designed to tell a pilot their

bearing from the beacon’s location.

A DVOR installation radiates an FM radio signal with separate modulations, which are

received by equipment onboard an aircraft. The Grand Baie DVOR is regularly calibrated

against an established standard to ensure the navigation data is sufficiently accurate.

The maximum acceptable error was exceeded during calibration in May of 2017.

The Eole Plaine Des Roches wind farm was considered to be a potential cause for the

interference, which required a technical investigation.

Pager Power Case Study Eole Plaine Des Roches Wind Farm Case Study 5

3 THE CHALLENGE

Interference to a DVOR can occur for many reasons, including interference to the

radiated signal by objects on the ground. Wind farms can be the source of such

interference, but so can other environmental or manmade features.

In addition, calibration of the DVOR had shown acceptable accuracy after the wind farm

became fully operational, which could indicate that the turbines were not the cause, or

potentially only a contributory factor.

The challenges were therefore:

1. Determining the sequence of events regarding construction and operation of the

wind farm alongside the measured performance of the DVOR;

2. Quantifying the potential effect of the wind farm.

3. Investigating other potential sources of interference to determine the likely cause

of the impact on the DVOR.

Figure 2: Potential interference mechanism from wind turbines

Pager Power Case Study Eole Plaine Des Roches Wind Farm Case Study 6

4 THE PROCESS

Pager Power undertook a detailed technical assessment of the wind farm’s potential

impacts on the DVOR. The process was as follows:

a) Collection and review of the points listed below in coordination with the wind

farm developer and the Department of Civil Aviation:

a. Wind farm construction (dates).

b. Wind farm operation (dates).

c. Calibration data for the DVOR.

b) Technical analysis of the wind farm’s potential impact on the DVOR, including

radio line of sight calculations and assessment in line with International Civil

Aviation Organisation (ICAO) guidelines.

c) Desk-based investigation of other potential sources of interference.

Figure 3: ICAO assessment process

Pager Power Case Study Eole Plaine Des Roches Wind Farm Case Study 7

5 THE SOLUTION

Pager Power was able to demonstrate with a high degree of certainty that the Eole

Plaine Des Roches Wind Farm was not the cause of the reported interference to the

Grand Baie DVOR.

This conclusion was underpinned by two key elements:

1. The analysis showed that the technical impact of the wind turbines on the Grand

Baie DVOR would be minimal due to:

a. The radio line of sight margin.

b. The separation distance between the wind farm and the DVOR.

c. The timeline of construction/operation of the wind farm and the calibration

data.

2. Identification of other building developments that had greater potential to impact

the DVOR. Specifically, buildings that were constructed in close proximity to the

DVOR and were also significantly within radio line of sight.

The results of the assessment were subsequently made available to the Department of

Civil Aviation.

Pager Power Case Study Eole Plaine Des Roches Wind Farm Case Study 8

6 THE RESULT

Pager Power’s analysis allowed the wind farm operator to satisfactorily demonstrate

that the Eole Plaine Des Roches development was not adversely impacting the Grand

Baie DVOR.

No further concerns relating to the wind farm were subsequently raised by the

Department of Civil Aviation.

An aerial image of the wind farm is shown in Figure 4 below1.

Figure 4: Eole Plaine Des Roches Wind Farm

1 Source: Copyright ©2018 Google, DigitalGlobe.

Pager Power Case Study Eole Plaine Des Roches Wind Farm Case Study 9