NB/T 10104-2018Specification for surveying of offshore wind power projects (English PDF)

Foreword

This document was issued on 25 December 2018 by the National Energy Administration of the PRC and takes effect on 1 May 2019.

It is a NB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

It is classified under ICS 27.180, Chinese classification P 61.

This specification was prepared in accordance with the requirements of the Notice of the National Energy Administration on Issuing the Plan for the Formulation and Revision of Energy Sector Industry Standards, Second Batch of 2014 (Guo Neng Ke Ji [2015] No. 12). The drafting group carried out extensive investigation and research, earnestly summarised practical experience, referred to relevant advanced standards in China and abroad, and prepared this specification on the basis of a wide solicitation of opinions.

The main technical contents of this specification are: control survey; water level control; topographic survey; special survey; spatial data editing and geographic information system development; and inspection, acceptance and archiving.

This specification is under the administration of the National Energy Administration. The China Renewable Energy Engineering Institute proposed this specification and is responsible for its routine administration.

The Sub-Technical Committee on Wind Farm Planning and Design of the Wind Power Standardization Technical Committee of the Energy Industry is responsible for the interpretation of the specific technical contents. Should any comment or suggestion arise in the course of implementation, it should be sent to the China Renewable Energy Engineering Institute, at No. 2 Liupukang Beixiaojie, Xicheng District, Beijing, postcode 100120.

Chief compiling organisations of this specification: PowerChina Huadong Engineering Corporation Limited; Zhejiang Huadong Mapping and Geoinformation Co., Ltd.

Participating compiling organisation of this specification: Zhejiang Huadong Construction Engineering Co., Ltd.

Main drafters of this specification: Yan Zhanglin, Shan Zhigang, Shi Jianwei, Feng Lei, Gao Hongqi, Wang Mingyuan, Zhu Chengrui, Shi Jinxiang, Luo Xujia, Xu Weihong, Jiang Peiwu, Xu Zhongbiao, Weng Pengfei, Li Xingkai, Zhang Kun, Li Xiaofei, Xu Jian and Yan Peng.

Main reviewers of this specification: Bao Jingyang, Guo Jiming, Wang Huiming, Huang Jingbo, Lu Enfeng, Gou Shengguo, Xiao Shengchang, Xie Niansheng, Liu Dongqing, Ren Shaohua, Liu Guiping, Ying Yuankang, Bao Jiang, Xi Minwei, Tang Wenyu and Li Shisheng, together with one further expert, seventeen reviewers in all.

Publication and Approval Data

The cover of the document identifies it as an Energy Industry Standard of the People's Republic of China, designation NB/T 10104-2018.

The International Classification for Standards number shown on the cover is ICS 27.180, and the Chinese Standard Classification number is P 61.

The filing number recorded on the cover is J2646-2019.

The Chinese title of the document is the specification for surveying of offshore wind farm engineering projects; the official English title printed on the cover and on the title page is Specification for Surveying of Offshore Wind Power Projects.

The cover states that the standard was issued on 25 December 2018 and came into force on 1 May 2019. The issuing body named at the foot of the cover is the National Energy Administration.

The title page states that the chief editing department is the China Renewable Energy Engineering Institute, that the approving department is the National Energy Administration, and that the date of implementation is 1 May 2019.

The title page carries the publication line Beijing, 2019.

The document reproduces Announcement No. 16 of 2018 of the National Energy Administration. In accordance with the Notice of the National Energy Administration on Issuing the Administrative Measures for Standardization in the Energy Sector (Trial) and the Detailed Rules for their Implementation (Guo Neng Ke Ji [2009] No. 52), and following examination, the National Energy Administration approved 204 industry standards, headed by the Code for Geological Investigation of Photovoltaic Power Generation Projects, of which 32 are energy standards (NB) and 172 are electric power standards (DL), and issued them. The announcement is dated 25 December 2018 and carries an attached catalogue of industry standards.

In the attached catalogue of industry standards this document appears as serial number 5, standard number NB/T 10104-2018, with no superseded standard and no adopted international standard indicated, an approval date of 25 December 2018 and an implementation date of 1 May 2019.

Structure of the Document

The official English contents page of the document lists nine numbered chapters, seven appendices and three items of back matter. The pagination given below is that printed in the contents.

Chapter 1, General Provisions, begins on page 1.

Chapter 2, Terms, begins on page 2.

Chapter 3, Basic Requirements, begins on page 3.

Chapter 4, Control Survey, begins on page 5 and is divided into 4.1 General Requirements (page 5), 4.2 Horizontal Control Survey (page 5), 4.3 Vertical Control Survey (page 7) and 4.4 Documentation (page 11).

Chapter 5, Water Level Control, begins on page 12 and is divided into 5.1 General Requirements (page 12), 5.2 Tidal Station Setting (page 13), 5.3 Water Level Observation (page 15), 5.4 Mean Sea Level Determination (page 16), 5.5 Sounding Datum Determination (page 17) and 5.6 Documentation (page 18).

Chapter 6, Topographic Survey, begins on page 19 and is divided into 6.1 General Requirements (page 19), 6.2 Coastal Topographic Survey (page 20), 6.3 Bathymetric Survey (page 21), 6.4 Topographic Map Compilation (page 24) and 6.5 Documentation (page 26).

Chapter 7, Special Survey, begins on page 27 and is divided into 7.1 Exploration Point Survey (page 27), 7.2 Navigation Aids Survey (page 27), 7.3 Submarine Obstacle Detection (page 28), 7.4 Seabed Pipeline Route Survey (page 28), 7.5 Sea Area Use Register Survey (page 29), 7.6 Construction Survey (page 31), 7.7 As-Built Survey (page 31) and 7.8 Deformation Monitoring (page 32).

Chapter 8, Spatial Data Editing and GIS Development, begins on page 34 and is divided into 8.1 General Requirements (page 34), 8.2 Spatial Data Editing and Storage (page 34) and 8.3 GIS Development (page 35).

Chapter 9, Inspection, Acceptance and Archiving, begins on page 37 and is divided into 9.1 Inspection and Acceptance (page 37) and 9.2 Archiving (page 37).

Appendix A, Mean Sea Level Determination Methods for Short-Term and Temporary Tide Stations, begins on page 39.

Appendix B, Operational Requirements for Bathymetric Survey by RTK Without Tidal Observation, begins on page 41.

Appendix C, Tests on Stability and Navigation for Single-Beam Echosounder, begins on page 43.

Appendix D, Operational Requirements for Multibeam Sounding System, begins on page 44.

Appendix E, Operational Requirements for Side Scan Sonar Survey, begins on page 47.

Appendix F, Operational Requirements for Sub-Bottom Profiler Survey, begins on page 51.

Appendix G, Operational Requirements for Marine Magnetic Survey, begins on page 54.

The back matter comprises the Explanation of Wording in This Specification (page 56), the List of Quoted Standards (page 57) and the Addition: Explanation of Provisions (page 59).

The front matter of the document is paginated in Roman numerals and comprises the announcement of the National Energy Administration, the attached catalogue of industry standards, the foreword and the bilingual contents.

The technical body of the document runs from page 1 to page 38, the appendices from page 39 to page 55, and the explanatory back matter from page 56 onwards.

1 Scope

NB/T 10104-2018 governs the surveying work on offshore wind farm projects in China. Offshore surveying is a different discipline from surveying on land: there is no stable ground to stand on, the control network has to be carried out to sea, positions are fixed by satellite in real time from a moving vessel, and the surface being mapped is the seabed rather than the ground. The specification sets the general requirements, the datum and coordinate systems to be used, and the accuracy classes appropriate to each stage of a project. It then covers the establishment of horizontal and vertical control, including the transfer of level offshore and the determination of the tidal datum from tide gauge observation. Bathymetric survey follows - single and multibeam echo sounding, the calibration and the sound velocity correction, the tidal reduction, the line spacing and coverage, and the quality checks on the resulting surface - together with side scan sonar and sub-bottom profiling, and the magnetometer survey used to find cables, pipelines and unexploded ordnance. The positioning of boreholes and of in-situ tests, the as-built survey of installed foundations and their verticality, the survey of the onshore substation and of the cable landfall, and the deformation monitoring of completed structures each have their requirements. Data processing, the drawings and charts produced, and the survey report close the specification. It applies at every stage of an offshore wind project, from feasibility to operation.

Chapter 1 sets out the purpose, the field of application and the relationship of this specification to other standards. It occupies page 1 of the document and contains three articles.

1.0.1 This specification is formulated in order to standardise the contents, methods and technical requirements of surveying for offshore wind power projects and to ensure the quality of the survey results.

1.0.2 This specification is applicable to the surveying work of offshore wind power projects.

1.0.3 In addition to complying with this specification, surveying for offshore wind power projects shall also comply with the provisions of the relevant current national standards.

2 Terms

Chapter 2 defines seven terms used throughout the document, each given with its Chinese designation and its English equivalent.

2.0.1 Sounding datum: the reference surface from which the depths shown on bathymetric charts and contained in the various kinds of water depth data are reckoned.

2.0.2 Lowest normal low water: the lowest water level that can theoretically occur; it is the sounding datum at present adopted in China.

2.0.3 Real-time kinematic relative positioning (RTK): a method based on the principle of carrier phase differencing in which radio communication technology is used to transmit the differential data of the reference station to the satellite positioning receiver of the roving station; by means of the resolution of those data the relative positioning of the real-time moving trajectory of the antenna of the roving station receiver is determined. It is also known as real-time carrier phase kinematic survey, or RTK survey.

2.0.4 Satellite-based augmentation GNSS system: a positioning system that achieves improved positioning accuracy on the basis of GNSS positioning correction information broadcast by communication satellites.

2.0.5 Tidal station: an observation station established at a selected site, equipped with a self-recording tide gauge or a tide staff, to record the variation of the water level and thereby to ascertain the law of tidal variation in the sea area concerned.

2.0.6 Bathymetric chart: a chart in which the underwater depth is represented by topographic symbols, depth contours and depth annotations, drawn up from the plane positions and the depths of the sounding points.

2.0.7 Route investigation: the investigation of the submarine topography and geomorphology, the marine geology, the geophysical characteristics and the hydrological elements of the sea area to be crossed, carried out before a submarine pipeline or cable is laid.

3 Basic Requirements

3.0.1 Before the work is started, the relevant data should be collected and analysed, a site reconnaissance should be carried out and a technical design document should be prepared; quality control should be exercised during the course of the work; and after the work has been completed a technical summary report should be prepared.

3.0.2 The selection or establishment of the plane coordinate system and of the elevation datum shall comply with the relevant provisions of the current national standard Code for Engineering Surveying GB 50026.

3.0.3 The sounding datum shall adopt the theoretical lowest tide level. In areas where the sounding datum has already been determined, the determined value shall be used; in areas where the sounding datum has not been determined, it shall be derived by joint observation with a nearby long-term tidal station.

3.0.4 The selection of the mapping scale shall comply with the provisions of Table 3.0.4, which sets out, for each stage of the project and each part of the works, the scales to be used.

Table 3.0.4 assigns to the planning stage, for the wind farm area, the scales 1:10 000, 1:25 000 and 1:50 000; to the pre-feasibility study stage, for the wind farm area, the scales 1:5 000 and 1:10 000; and to the feasibility study stage, for the wind farm area, the scales 1:2 000 and 1:5 000.

For the tendering and construction detailed design stage, Table 3.0.4 assigns the scales 1:500 and 1:1 000 to the submarine cable layout area, the scales 1:500 and 1:1 000 to the onshore centralised control centre and step-up substation layout area, the scale 1:500 to the offshore booster station layout area, and the scales 1:200 and 1:500 to the wind turbine generator unit position layout area.

3.0.5 For topographic maps at scales of 1:200 and 1:500 the basic contour interval shall be 0.5 m; for topographic maps at the remaining scales the basic contour interval is appropriately 1.0 m.

3.0.6 Topographic maps at scales from 1:500 to 1:50 000 should be divided into sheets and numbered in accordance with the relevant provisions of the current national standard Specifications for Sheet Subdivision and Numbering of National Basic Scale Topographic Maps GB/T 13989; for topographic maps at the scale of 1:200 and for areas in which an independent coordinate system is adopted, square or rectangular sheet division may be used, with sequential numbering according to the survey area; and for belt-shaped and irregular survey areas free sheet division may be used.

3.0.7 Instruments and the related equipment shall be inspected and calibrated, and their maintenance and upkeep shall be strengthened; the software used shall have passed appraisal or examination.

3.0.8 The survey accuracy shall take the mean square error as its criterion, and twice the mean square error shall be taken as the limiting error.

3.0.9 Existing topographic maps shall first be checked in the field, and shall then be revised or resurveyed in accordance with the results of that check.

3.0.10 Records of field observations should be kept by means of an electronic field book or a data terminal.

3.0.11 Before field work is undertaken for the surveying of an offshore wind power project, identification of the hazard sources of the working sea area and assessment of the safety risks shall be carried out, and safety risk control measures and emergency plans shall be drawn up; the operating personnel shall have received offshore safety education and training.

3.0.12 When surveying work for an offshore wind power project is carried out, the waste and the domestic refuse generated shall be treated.

4 Control Survey

4.1.1 A fourth-order or first-class horizontal control network shall be established in accordance with the relevant provisions of the current national standard Code for Engineering Surveying GB 50026, to serve as the primary horizontal control of the survey area.

4.1.2 Horizontal control survey should adopt the GNSS surveying method, or else the traverse surveying method.

4.1.3 A fourth-order or fifth-order vertical control network shall be established, to serve as the primary vertical control of the survey area.

4.1.4 Vertical control should adopt the levelling method, or the electromagnetic distance measurement trigonometric levelling method; for the fifth order, the GNSS heighting method may also be adopted.

4.2.1 The accuracy requirements of the GNSS control network and the average side length between adjacent points shall comply with the provisions of Table 4.2.1.

For a fourth-order network, Table 4.2.1 requires an average side length between adjacent points of 2 km to 4 km, a fixed error A of not more than 10 mm, a scale error B of not more than 10 parts per million, and a relative mean square error of the weakest adjacent-point side length of not more than one fortieth of a hundred thousand, that is 1/40000.

For a first-class network, Table 4.2.1 requires an average side length between adjacent points of 0.5 km to 2.0 km, a fixed error A of not more than 10 mm, a scale error B of not more than 20 parts per million, and a relative mean square error of the weakest adjacent-point side length of not more than 1/20000.

The note to Table 4.2.1 provides that where the side length of the control network is less than 0.5 km, the accuracy shall be computed on the basis of 0.5 km.

4.2.2 The main technical indicators of static GNSS control network survey shall comply with the provisions of Table 4.2.2.

4.2.3 First-class GNSS survey may adopt RTK survey; in areas where a network of continuously operating reference stations (CORS) has been established, CORS should be used to carry out the RTK survey. The main technical requirements of RTK survey shall comply with the provisions of Table 4.2.3.