Waverley Windfarm. Trustpower Limited. Radio Effects Report. Trustpower (Chris Fern) Chancery Green on Behalf of Trustpower Limited

Transcription

1 Issue Nov 2015 Document Number: 692H001R Final to: Prepared for: Trustpower (Chris Fern) Chancery Green on Behalf of Rodgers Hulston & White Limited Unit 3, 35 Riccarton Rd PO Box 8556 Christchurch 8440, New Zealand T

2 Revision History Issue No Date Prepared by Comments 1 9/12/14 Graham Hulston 2 14/10/15 Graham Hulston /11/15 Graham Hulston /11/15 Graham Hulston /12/15 Graham Hulston Final version Document Review Section Reviewer Designation Date Document Distribution 692H001R: Issue Nov of 25

3 Table of Contents 1 Glossary of technical terms used 5 2 Background Radio Sites in the Region 8 3 Potential effects from Waverley Wind Farm Potential Radio Communication Effects Design assumptions and constraints Diffraction Analysis Fixed Radio Links: Point to Point (PTP) Area Coverage Services: Land Mobile and TV/FM Broadcast 11 4 Scatter Analysis Effect of Scattering Point to Point Links Area Coverage Services 13 5 Summary of Effects 15 6 Appendices H001R: Issue Nov of 25

4 Table of Appendices Appendix A: Fixed Radio Link Locations 17 Appendix B: Cellsite Locations 18 Appendix C: LMR Sites 19 Appendix D: Broadcast Sites 20 Appendix E: Misc and Wireless Access Sites 21 Appendix F: Maritime Repeater Sites H001R: Issue Nov of 25

5 1 Glossary of technical terms used Area Coverage: These are radio services which consist of a central/hub/base radio, like PTMP, which is a fixed location but the other end of the radio link is mobile. Examples of this are Land Mobile and Cellular. These services are designed to provide communication for mobile radios over a large area as opposed to specific locations. Communication is bidirectional and they operate in VHF and UHF bands. Broadcast: This type of radio services is a variation on Area Coverage with the difference being that the communication is uni-directional from the central/hub/base transmitter to a fixed or portable/mobile receiver. The main types of broadcast service are: AM sound broadcasting ( MHz); FM sound broadcasting (88 108MHz); Television broadcasting (44 68, , MHz). Cellular Mobile: Cellular mobile is the now ubiquitous public mobile telephony service that was introduced into New Zealand in the late 1980s. Cellular mobile networks employ numerous base stations, usually up to around 25m high, ranging in cell coverage from a few hundred metres to many kilometres, depending on the area to be covered and the anticipated traffic load within. The cellular mobile frequency bands in New Zealand are in the UHF range around 900MHz, and also more recently around 2000MHz. C/I (ratio): The ratio of the wanted signal (C) with respect to the unwanted interference (I), usually expressed in decibels. For a given radio service there is minimum C/I needed to ensure the effect of interference is imperceptibile. Diffraction Loss: Reduction in power of a propagating wave caused by the bending of waves around an object. EMI: Electromagnetic Interference (EMI) occurs when the electrical and electronic equipment inside a wind turbine generator radiates radio frequency energy in a frequency band used by a radio service. Fresnel Zone: Fresnel zones result from diffraction by a circular aperture. For radio link planning the 1 st Fresnel Zone is used to define the region around the radio path where an object (e.g. building, tree, ground) 692H001R: Issue Nov of 25

6 may cause attenuation of the radio signal by diffraction if the objects blocks the 1 st Fresnel Zone (or part of it). Fixed Linking: A Fixed Link is where the ends of a radio link are fixed in location i.e. not mobile. Fixed links employ highly directive antennas that are intended to transmit or receive radio signals only in one direction, and operate in the VHF, UHF, and SHF. Interference: The effect of unwanted energy due to one or a combination of emissions, radiations, or inductions upon reception in a radiocommunication system, or loss of information which could be extracted in the absence of such unwanted energy. (International Telecommunication Union Radio Regulations). ITU: The ITU (International Telecommunications Union) - a UN (United Nations) organisation that sets international rules and recommendations for telecommunications and radio communications. ITU-R refers to radio communications part of the ITU. Land Mobile Land Mobile services provide personal two-way wireless voice communications between portable transceiver terminals routed via a base station which is usually situated at a high prominent location to provide wide area coverage. Land Mobile services are often used by taxis, emergency services, couriers, etc. and make use of hand portable and vehicular terminals. The Land Mobile frequency bands in New Zealand are in the VHF range at around 80 and 160MHz, UHF from 400 to 500MHz and 800MHz. Near-Field Effects: Occurs when a wind turbine is located in close proximity to an existing antenna, such that it modifies the radiation characteristics of the antenna. PTMP: Point to Multipoint - this is a type of fixed linking where two or more fixed points communicate to and from the same central/hub/base site using the same radio equipment at the hub site. A PTMP system can be considered to consist of a number of PTP links. PTP: Point to Point - this is a type of fixed link where the radio equipment only provides communication between two geographical points. Radio Link: A radio link is a communication circuit which consists of a transmitter at one end and a receiver at the other end. The 692H001R: Issue Nov of 25

7 transmitter via an antenna radiates a modulated electromagnetic wave, which is demodulated by a receiver via an antenna. Radio Signal Scattering: This is where delayed "echo" signals of the wanted signal or interference from another radio link arrive at a victim receiver via reflection (scattering) off the wind turbines causing noise and distortion to the signal received via the direct path. Radio Service: Refers to the purpose of the radio link e.g. FM radio, TV, Cellular, Land Mobile. RCS: Radar Cross Section - it represents how much radio power is reflected off the object in terms of an equivalent area and does not correspond to physical size. RCS is sometimes expressed as dbsm, decibel square metres (10LOG RCS in square metres). RSM: Radio Spectrum Management - the group within the Ministry of Business Innovation and Employment responsible for managing the radio spectrum in New Zealand. SHF: Super High Frequency officially defined as the range 3000 MHz to MHz and often referred to as Microwaves. VHF: Very High Frequency officially defined as the range 30 MHz to 300 MHz. UHF: Ultra High Frequency officially defined as the range 300 MHz to 3000 MHz and includes part of the region often referred to as Microwaves. 692H001R: Issue Nov of 25

8 2 Background Trustpower proposes to construct, operate and maintain a wind farm on the coast south of Waverley Township, South Taranaki. This report analyses the potential for the wind turbines to obstruct radio links that pass through the proposed wind farm location, along with an assessment of the scatter risk. 2.1 Radio Sites in the Region Fixed Links The map in Appendix A: Fixed Radio Link Locations shows the position of PTP radio links closest to the proposed wind farm Cellular These are sites used by 2Degrees, Spark, or Vodafone for Cellular basestations; see map in Appendix B: Cellsite Locations. Service Provider Frequency (MHz) Site Name Distance from Wind Farm (km) VODAFONE NEW ZEALAND LIMITED 785.5/952 WAVERLEY 10 SPARK NEW ZEALAND TRADING LIMITED WAVERLEY 10 TWO DEGREES MOBILE LIMITED 939.9/ (COW L)[CWAV]_ STATE HIGHWAY 3, PATEA- NUKUMARU, WAVERLEY 10 SPARK NEW ZEALAND TRADING LIMITED RICHMOND WAITOTARA 17 SPARK NEW ZEALAND TRADING LIMITED HURLEYVILLE 19 VODAFONE NEW ZEALAND LIMITED 952 Table 1: Cell sites closest to Waverley Wind Farm PATEA 19 Note distances are measured relative to centre of wind farm Land Mobile Radio (LMR) These are sites where LMR radio repeaters are located; see map in Appendix C: LMR Sites Broadcast These are sites where TV or sound broadcasting (FM) transmitters are located; see map in Appendix D: Broadcast Sites. 692H001R: Issue Nov of 25

9 Servicee Site Distance from Wind Farm (km) FM LANDGUARD 46 FM and DTV MT JOWETT 46 FM DURIE HILL 47 FM BASTIA HILL 47 FM CARDIFF 58 FM AUROA ROAD 62 FM WAIPUNA 67 FM and DTV MT TARANAKI 69 FM KINA RD 74 FM KAHUI TRIG 74 FM KORITO RD 78 FM PUKEITI 82 FM PARIHAKA 83 FM POUTOKO 91 FM OAKURA 91 Table 2: Broadcast Sites closest to Waverley Wind Farm Miscellaneous and Wireless Access Sites These are sites used for radio telemetry transmitters or PTMP Wireless Access basestations; see map in Appendix E: Misc and Wireless Access Sites Maritime Repeater Sites These are sites where radio repeaters for maritime communications are located; see map in Appendix F: Maritime Repeater Sites. Client Name Frequency (MHz) Site Name Distance from Wind Farm (km) Distance from Wind Farm (km) SOUTH TARANAKI VOLUNTEER COASTGUARD Ministry of Business, Innovation, and Employment (RSM) (CH83) HURLEYVILLE (CH64) HURLEYVILLE 18 MARITIME NEW ZEALAND (AIS1) (CH69) (CH16) (CH70) (AIS2) KURANUI 26 Table 3: Maritime Repeater Sites closest to Waverley Wind Farm Note distances are measured relative to centre of wind farm 692H001R: Issue Nov of 25

10 3 Potential effects from Waverley Wind Farm 3.1 Potential Radio Communication Effects Wireless communication systems use radio waves to relay information from a transmitter to a receiver. In some circumstances, it is possible for wind turbines to cause interference to wireless receivers. There are four distinct mechanisms that can potentially cause interference to a radio service: Electromagnetic Interference (EMI) Near-Field Effects Diffraction Reflection (or Scattering) In general EMI interference is not a problem and nor is Near-Field Effects provided the turbines are at least 500m away from a radio site. The more relevant areas of concern are Diffraction (obstruction of radio paths) and Scatter (reflection off the turbine blades). 3.2 Design assumptions and constraints The analysis relies on external data sources that have a limited accuracy. These accuracies are: Terrain data: ±10m vertical and ±25m horizontal. RSM database: Assumed to contain accurate licence information regarding site placement, transmit/receive height and transmit/receive frequency. Site coordinate accuracy ±20m horizontal. The analysis uses a maximum tip height for the turbines of 160m. 692H001R: Issue Nov of 25

11 3.3 Diffraction Analysis Effect of Diffraction Diffraction of radio signals occurs around obstacles (e.g. buildings, trees, and ground) and results in attenuation of the radio signal. This is undesirable because it may attenuate the receive signal below the minimum working threshold for the link or make it more vulnerable to atmospheric fading. The region around the path where the link is vulnerable to diffraction is called the 1 st Fresnel Zone. Any object extending into it will cause diffraction of the radio signal. The region is defined by an ellipsoid with a circular cross section (for example, Figure 1) Cross Section 1 st Fresnel Zone Radius Ist Fresnel Zone Ellipsoid Radio Site 2 Radio Site 1 Figure 1: Fresnel Zone Side Elevation Profile Radio clearance is based on ensuring that the radio path has at least 1 st Fresnel zone clearance at K=4/3 (related to the refractive index of the atmosphere) when the signal path passes either over or beside the turbine. This clearance criterion is based on ITU-R recommendation P.530 and ensures there is no additional path loss caused by diffraction Fixed Radio Links: Point to Point (PTP) As shown on the map in Appendix A: Fixed Radio Link Locations there are no links that either cross the wind farm or pass close to it and hence there no risk of the turbines obstructing radio paths Area Coverage Services: Land Mobile and TV/FM Broadcast Area coverage services use antennas that receive and transmit over a wide angle (60 to 360 degrees) to provide coverage to as large an area as possible. Therefore, these services are more vulnerable since there can be instances, depending on the mobile location or household, where radio paths are obstructed by a turbine. In such cases, diffraction around each wind turbine casts a narrow signal shadow behind it. Simple theoretical calculations indicate that the average signal loss behind a wind turbine 200 m from a transmitter site is 4.5 to 6dB for VHF/UHF communications services. These levels do 692H001R: Issue Nov of 25

12 not change significantly for various distances behind the wind turbine. At ±1 to ±2 off boresight to each wind turbine, the signal loss drops to between 0 and 3 db. Cellular Given the coastal location of the wind farm there will be some shading of cellular coverage from the Waverley cellular site on the sea behind the wind farm. Given that this is not in the prime coverage region (the main area where the majority of radio users are) then it is not considered a concern. Land Mobile/Broadcast/Miscellaneous/ Wireless Access Sites Same consideration as for cellular applies. Maritime The predicted coverage maps in Appendix F: Maritime Repeater Sites show the areas where reliable communication is possible (SINAD>20dB) between the basestation and mobile radio for the worst case receive direction i.e. from the mobile transmitter to the basestation receiver. They show there is likely to be some shading in coverage from both the Hurleyville and Kuranui radio sites. The Kuranui repeater site is used by Maritime NZ for emergency calls (CH16). However, as Maritime NZ has repeaters at Kahui Trig and Mt Taranaki which provide coverage in the shadow area then it is unlikely that CH16 coverage will be affected by the wind farm. It would be wise to discuss the potential problem with the Maritime NZ. 3.4 Scatter Analysis Effect of Scattering Scattering can cause interference to nearby radio services. The extent of the impact depends on the strength of the received echoes relative to the direct path signal (Carrier to Interference ratio or C/I) and delay of the received echoes relative to the direct path signal, the fade margin of the victim radio service, and the countermeasures used in the victim receiver. Strong, long delay echoes are particularly problematic for radio reception. 692H001R: Issue Nov of 25

13 Scattered Signal from Transmitter to Receiver via Turbine Direct Signal from Transmitter to Receiver TX RX Fig 2: Scatter from Turbine Point to Point Links As shown on the map in Appendix A: Fixed Radio Link Locations there are no links either crossing the wind farm or passing close to it and hence there is no risk of scatter affecting PTP links Area Coverage Services Land Mobile and Cellular Outside Wind Farm The wind farm is approximately 3km away from State Highway 3 between Waverley and Patea and hence the wind farm has the potential to cause scatter to mobile communication as vehicles travel along this road. The scatter analysis contours for cellular (see Appendix B: Cellsite Locations) shows that the Carrier to Interference (C/I) is at least 29dB and hence there is unlikely to be any degradation of cellular reception outside the wind farm. The same applies to Land Mobile reception. Within Wind Farm However within the wind farm, it is likely that reception for Land Mobile and Cellular services could be affected as the predicted Carrier to Noise is less than 20dB which would make reception unreliable in some locations. To mitigate this risk Trustpower may need to consider installing within the wind farm an alternative non-wireless form of communication (e.g. telephone system using fibre optic cables) to provide emergency communications for maintenance and operation staff. Maritime Mobile Given the wind farm s location close to the coast there is a risk of scatter affecting maritime reception adjacent and within 1km of the wind farm. See Appendix F: Maritime Repeater Sites. This is probably a minor concern for Martime NZ as they already have areas close to the coast with poor coverage as they note on their coverage map (see Appendix F) From time 692H001R: Issue Nov of 25

14 to time gaps may exist with the areas shown due to terrain shadowns and system maintenance. Terrain shadows can occur close to the shore under cliffs or in bays and fiords. Broadcast The closest house appears to be at least 1km away from the perimeter of the windfarm. Given this distance is unlikely that either terrestrial digital TV or FM radio reception will be affected. 692H001R: Issue Nov of 25

15 4 Summary of Effects Risk of Interference Interference Mechanism Fixed Linking Cellular Land Mobile Radio (LMR) Broadcast Miscellaneous and Wireless Access Sites Maritime Electromagnetic Interference (EMI): Occurs when the electrical and electronic equipment inside a wind turbine generator radiates radio frequency energy in a frequency band used by a radio service. Near-Field Effects: Occurs when a wind turbine is located in close proximity to an existing antenna, such that it modifies the radiation characteristics of the antenna. Very low as turbines are at least 1km away from nearest house in terms of affecting radio/phone/tv/wireless Broadband reception. No risk to radio site since all are at least 10km way from the wind farm. Also to date there has been no reported issues with this type of interference from any wind farms in New Zealand. No risk as all turbines are in the far field region for any antenna associated with the nearest radio sites. The minimum distance from the radio site increases with frequency and is typically at least 500m at microwave frequencies. Diffraction: Occurs when a wind turbine s location causes radio waves to be partially blocked, causing some signal power loss. No risk. Proposed turbines not obstructing any existing radio paths Very low risk. Proposed turbines are located on the coast and hence there is no shadowing of primary coverage areas behind the wind farm. There is a moderate risk that maritime VHF radio coverage from the Kuranui radio repeater site will be affected. This is unlikely to be a problem in practice given coverage from other Maritime NZ repeaters in the area. Reflection (or Scattering): Occurs when radio waves are reflected from a wind turbine s surface. No risk. There are no links that either cross the wind farm or pass close to it. Outside wind farm. Low risk as wind farm is approximately 3km away from State Highway 3 between Waverley and Patea and nearest house to wind farm is approximately 1km away. Within wind farm Very low risk Nearest household is at least 1km away from wind farm Low risk for boats at least 1km off the coast from the wind farm. High risk that reception will unreliable. Therefore, non-wireless communication options should be considered on-site. 692H001R: Issue Nov of 25

16 5 Appendices 692H001R: Issue Nov of 25

17 Appendix A: Fixed Radio Link Locations 692H001R: Issue Nov of 25

18 Appendix B: Cellsite Locations Scatter Contour C/I (db) 692H001R: Issue Nov of 25

19 Appendix C: LMR Sites 692H001R: Issue Nov of 25

20 Appendix D: Broadcast Sites Scatter Contour C/I (db) 692H001R: Issue Nov of 25

21 Appendix E: Misc and Wireless Access Sites 692H001R: Issue Nov of 25

22 Appendix F: Maritime Repeater Sites 1. Hurleyville Maritime Repeater Coverage 692H001R: Issue Nov of 25

23 2. Kuranui Radio Repeater Coverage 692H001R: Issue Nov of 25

24 3. Maritime NZ Coverage Maps Notes Maps show the areas where reliable communication is possible (SINAD>20dB) between the basestation and mobile radio. They are shown for the worse-case receive direction i.e. from the mobile transmitter to the basestation receiver. The minimum field strength is 17dBuv/m and assumes that a boat mounted 25W radio is used with an antenna mounted 4 m or more above the waterline. These are the same assumptions used by Maritime NZ for their VHF coverage map shown below. Calculation Parameters Software: Terrain Database: Diffraction Algorithm: Pathloss V5 area coverage module 25m grid data for land and 90m grid data for sea. Pathloss which is a combination of Longley Rice and Deygout. Time Variability: 50% Location Variability: 50% Basestation antenna height (agl): Mobile (Maritime) antenna height (amsl): 12m as per licence 4m Frequency: 158MHz Transmitter Power: 25W Antenna Gain: 2.15dBi (0dBD) Antenna Feeder loss: 2dB 692H001R: Issue Nov of 25

25 4. Maritime NZ VHF Coverage 692H001R: Issue Nov of 25