NB/T 31032-2019Specification for preparation of feasibility study report for offshore wind power projects (English PDF)

Foreword

This document was issued on 4 November 2019 by the National Energy Administration of the PRC and takes effect on 1 May 2020.

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.

It replaces NB/T 31032-2012, which is superseded.

NB/T 31032-2019 is an energy industry standard of the People's Republic of China, approved by the National Energy Administration through Announcement No. 6 of 2019, issued on 4 November 2019 and put into force on 1 May 2020. It replaces NB/T 31032-2012, which is withdrawn on the same date.

The revision was carried out in accordance with the requirements of the Notice of the General Department of the National Energy Administration on Issuing the 2017 Plan for the Formulation and Revision of Energy Sector Industry Standards and the Plan for Translation and Publication of English Versions (Guo Neng Zong Tong Ke [2017] No. 52). The drafting group conducted extensive investigation and research, carefully summarized practical experience, referred to relevant Chinese and foreign standards and revised the specification on the basis of soliciting opinions widely.

The main technical content of this specification comprises: basic data; overview; wind energy resources; marine hydrology; engineering geology; project task and capacity; type selection and layout of wind turbines and energy output estimation; electrical system; fire protection design; civil works; construction organization design; sea and land use for project construction; environmental protection and soil and water conservation; occupational health and safety; energy saving; cost estimation; financial evaluation and social effect analysis; and bidding.

First revision item: the terms intertidal zone wind farm, far-shore wind farm, shallow-sea wind farm and hub height of wind turbine have been added to the chapter on terms.

Second revision item: a new chapter on basic data has been added, so that the data to be collected and verified before the report is prepared are stated explicitly.

Third revision item: three appendices have been added, namely the contents of the feasibility study report for an offshore wind power project, the contents of the research report on wind turbine foundation design for an offshore wind power project, and the contents of the research report on construction planning for an offshore wind power project.

This specification is under the administration of the National Energy Administration. It is proposed by, and under the routine management of, China Renewable Energy Engineering Institute (General Institute of Hydropower and Water Resources Planning and Design). 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 its specific technical content. Comments and suggestions arising during implementation should be sent to China Renewable Energy Engineering Institute, No. 2 Liupukang Beixiaojie, Xicheng District, Beijing, postcode 100120.

The chief editing organizations are PowerChina Huadong Engineering Corporation Limited and China Renewable Energy Engineering Institute. The participating organizations are PowerChina Zhongnan Engineering Corporation Limited, PowerChina Northwest Engineering Corporation Limited and Shanghai Investigation, Design and Research Institute Co., Ltd.

The foreword also lists by name the twenty-four chief drafters of the specification and the twenty-six principal reviewers who examined it. The chief editing department is China Renewable Energy Engineering Institute and the approving department is the National Energy Administration; the edition was published in Beijing in 2020.

Appendices and Back Matter

Appendix A, Contents of Feasibility Study Report for Offshore Wind Power Project, spans pages 59 to 62. Added by this revision, it gives the complete table of contents that the feasibility study report itself must follow, chapter by chapter and section by section.

Appendix B, Contents of Research Report on Wind Turbines Foundation Design for Offshore Wind Power Project, spans pages 63 and 64. Also added by this revision, it gives the table of contents of the special research report devoted to the design of the wind turbine foundations.

Appendix C, Contents of Research Report on Construction Planning for Offshore Wind Power Project, spans pages 65 and 66. Also added by this revision, it gives the table of contents of the special research report devoted to construction planning.

Appendix D, Table of Project Characteristics, spans pages 67 to 69. It sets out the standard table of project characteristics in which the principal technical and economic indicators of the wind farm are summarized.

Explanation of Wording in This Specification, on page 70, explains the degrees of obligation attached to the words used in the provisions, in the customary form of Chinese industry specifications.

List of Quoted Standards, on page 71, lists the national and industry standards referred to in the text.

Addition: Explanation of Provisions begins on page 73 and gives the clause by clause explanation of the provisions, stating the reasoning behind the requirements of the specification.

1 Scope

NB/T 31032-2019 fixes the content and the form of the feasibility study report for an offshore wind farm, replacing the 2012 edition. The feasibility study is the document on which an offshore wind project is approved and financed, and this specification tells the author exactly what must be in it, chapter by chapter, so that reviewers compare like with like. It covers the wind resource assessment based on offshore measurement, the marine environment - waves, tides, currents, sea ice, scour and typhoon conditions - and the geotechnical investigation of the seabed. It then sets out the requirements for the chapters on site selection and the marine functional zoning and navigation constraints that bound it, the turbine selection and micrositing, the energy yield calculation and its uncertainty, the foundation type selection, the offshore and onshore substation and the submarine cable route, the grid connection study, and the construction plan with its vessels, ports and weather windows. Operation and maintenance arrangements, health and safety, environmental impact and the protection of marine ecology, land and sea use, resettlement where it applies, fire protection, labour and the project organisation each have their prescribed chapter. Investment estimation and financial and economic evaluation close the report. The specification also fixes the drawings, tables and appendices that must accompany it. It applies to offshore wind power projects in China.

Clause 1, General Provisions, opens the body of the specification on page 1 and states the purpose of the document, the offshore wind power projects to which it applies and the general principles to be observed when a feasibility study report is prepared.

As is the rule for Chinese industry specifications of this family, preparation of a feasibility study report for an offshore wind power project must comply not only with this specification but also with the other current national and industry standards that are relevant to the subject matter.

2 Terms

Clause 2, Terms, occupies page 2 and defines the vocabulary used throughout the specification, so that the same wording is applied consistently in every chapter of the feasibility study report.

Intertidal zone wind farm is one of the four terms added by this revision. It designates a wind farm sited in the belt that is alternately covered and uncovered by the tide, between the high water line and the low water line, a siting condition that governs access, foundation type and construction method.

Shallow-sea wind farm is the second term added by this revision. It designates a wind farm sited in the shallow water area beyond the intertidal zone, where fixed foundations remain the normal solution and where marine hydrological and geological conditions are the dominant design constraints.

Far-shore wind farm is the third term added by this revision. It designates a wind farm sited in waters further offshore than the shallow-sea case, where water depth, distance from shore, transmission distance and construction and maintenance logistics become determining factors for the project.

Hub height of wind turbine is the fourth term added by this revision. It fixes the reference from which wind speed, energy output and turbine layout calculations are made, and links the wind energy resource chapter to the turbine selection chapter.

3 Basic Requirements

Clause 3, Basic Requirements, occupies page 3 and sets out the general rules governing the preparation of the feasibility study report: the tasks to be accomplished at the feasibility study stage, the depth of investigation and design work required and the conclusions the report must be able to support.

It also establishes the relationship between the main report and the special research reports and appendices, in particular the research report on wind turbine foundation design and the research report on construction planning, whose contents are prescribed in Appendices B and C.

4 Basic Data

Clause 4, Basic Data, spans pages 4 to 6 and is the chapter newly added by this revision. It lists the data that must be collected, verified and made available before the feasibility study report is compiled.

The data concerned cover the whole spread of the later chapters: wind measurement and meteorological records, marine hydrological observations, engineering geology investigations, power system and grid connection information, sea area and land use documents, environmental and safety background material, and the economic and financial parameters used in the cost estimate and the financial evaluation.

5 Overview

Clause 5, Overview, spans pages 7 to 9 and prescribes the content of the comprehensive summary chapter that opens the feasibility study report itself.

The overview brings together the project background and history, the main findings of every technical chapter, the recommended scheme, the principal technical and economic indicators and the conclusions and recommendations, so that the reader obtains the complete picture of the project before entering the detailed chapters.

6 Wind Energy Resources

Clause 6, Wind Energy Resources, spans pages 10 to 12 and prescribes the content of the wind resource chapter of the feasibility study report. It is divided into five sub-clauses.

6.1 General states the purpose and scope of the chapter and the sources and period of the wind data on which the assessment is based.

6.2 Analysis of Regional Meteorological Conditions requires the presentation of the meteorological regime of the region surrounding the project, including the long-term records of the reference meteorological stations and the extreme weather events relevant to an offshore site.

6.3 Analysis of Observed Wind Data on Site requires the presentation of the measurements taken at the site itself, their validation and completion, and their correlation with the long-term reference records.

6.4 Wind Energy Resource Assessment requires the assessment proper: the wind regime at hub height, the distribution of wind speed and direction, turbulence and shear, the wind farm class and the energy available for the project.

6.5 Tables and Figures lists the result tables and drawings that must be attached to the chapter, so that the wind resource findings are presented in a uniform form from one report to another.

7 Marine Hydrology

Clause 7, Marine Hydrology, spans pages 13 to 15 and prescribes the content of the marine hydrology chapter of the feasibility study report. It is divided into seven sub-clauses, one for each family of marine element.

7.1 General states the purpose of the chapter, the observation stations and data series used and the design conditions the chapter must deliver to the civil works and construction chapters.

7.2 Tide requires the presentation of the tidal regime of the site, the tidal levels and the design water levels derived from them.

7.3 Ocean Current requires the presentation of the current regime, including current speeds and directions and the design current conditions applicable to the foundations and to marine construction.

7.4 Wave requires the presentation of the wave regime, the wave parameters and the design wave conditions for the various return periods relevant to the structures of the wind farm.

7.5 Sea Ice requires the presentation of the sea ice conditions where they exist, which feed directly into the anti-icing design of sub-clause 13.10.

7.6 Sediment requires the presentation of the sediment regime, the movement of sediment at the site and the seabed evolution, which underlie the scour protection design of sub-clause 13.8.

7.7 Other Marine Hydrological Elements covers the remaining elements to be reported, such as the further hydrological and meteorological marine factors that may affect the layout, the construction or the operation of the wind farm.

8 Engineering Geology

Clause 8, Engineering Geology, spans pages 16 to 18 and prescribes the content of the engineering geology chapter of the feasibility study report. It is divided into five sub-clauses.

8.1 General states the purpose of the chapter and the investigation work on which it is based.

8.2 Regional Geology and Tectonic Stability requires the presentation of the regional geological setting, the seismic parameters and the assessment of the tectonic stability of the region.

8.3 Site Engineering Geological Conditions requires the presentation of the conditions at the site itself: the seabed stratigraphy, the properties of the soil layers, the groundwater and the adverse geological phenomena identified.

8.4 Assessment of Engineering Geological Conditions requires the evaluation of those conditions for the purposes of the project, including the bearing strata proposed for the wind turbine foundations and for the offshore step-up substation.

8.5 Tables and Figures lists the geological result tables, logs and drawings to be attached to the chapter.

9 Project Task and Capacity

Clause 9, Project Task and Capacity, spans pages 19 and 20 and prescribes the chapter in which the purpose of the project and its installed capacity are established.

The chapter covers the position of the project in the power system and in the regional development plan, the electricity market and grid connection conditions, the demonstration of the task assigned to the project and the determination of the wind farm capacity and of the boundaries of the works.

10 Type Selection and Layout of Wind Turbines and Energy Output Estimation

Clause 10 spans pages 21 and 22 and prescribes the chapter dealing with the wind turbines themselves, from machine selection through layout to the estimate of the electricity the wind farm will produce. It is divided into four sub-clauses.

10.1 Type Selection of Wind Turbines requires the comparison and selection of the candidate machines against the wind farm class, the marine environment and the technical and economic criteria applicable to the project.

10.2 Layout of Wind Turbines requires the arrangement of the machines over the sea area allotted to the project, taking into account the constraints on the use of that area and the mutual interference between machines.

10.3 Estimation of Energy Output requires the calculation of the theoretical and net energy output, the treatment of the wake and of the various loss factors and the resulting equivalent full load hours and capacity factor.

10.4 Tables and Figures lists the tables of machine parameters, layout coordinates and energy output, together with the layout drawings to be attached.

11 Electrical System

Clause 11, Electrical System, spans pages 23 to 29 and is one of the longest chapters of the specification. It prescribes the content of the electrical chapter of the feasibility study report and is divided into five sub-clauses.

11.1 General states the purpose and scope of the chapter and the grid connection conditions on which the electrical design is based.

11.2 Electrical Primary System covers the primary plant: the collector system of the wind farm, the step-up substations, the main electrical connection, the submarine and land cables, the transmission scheme and the auxiliary power supply.

11.3 Electrical Secondary System covers the secondary plant: protection, control and monitoring of the wind farm, metering, the wind farm supervisory system and the requirements arising from operation of an installation located at sea.

11.4 Communications covers the communication arrangements of the project, both those internal to the wind farm and those linking the wind farm with the dispatching authority of the power system.

11.5 Tables and Figures lists the electrical result tables, single line diagrams and cable route drawings to be attached to the chapter.

12 Fire Protection Design

Clause 12, Fire Protection Design, spans pages 30 and 31 and prescribes the fire protection chapter of the feasibility study report. It is divided into four sub-clauses.

12.1 General states the basis of the fire protection design and the fire safety features of an offshore wind farm, where the structures are unmanned for most of the time and access is by sea.

12.2 Project Fire Protection Design covers the fire protection measures designed into the permanent works, including the wind turbines, the offshore step-up substation and the onshore step-up substation or centralized control centre.

12.3 Construction Fire Protection Design covers the fire protection measures applicable during the construction period, on the marine works as well as on the onshore sites.

12.4 Tables lists the fire protection tables to be attached to the chapter.

13 Civil Works

Clause 13, Civil Works, spans pages 32 to 38 and is the longest chapter of the specification, with thirteen sub-clauses. It prescribes the content of the civil engineering chapter of the feasibility study report.

13.1 Design Standards requires the statement of the design standards and safety classes adopted for the structures of the wind farm.

13.2 Design Basis requires the statement of the design basis, that is, the loads and the environmental conditions derived from the marine hydrology and engineering geology chapters.

13.3 Project General Layout covers the general arrangement of the works, sea and shore taken together.

13.4 Wind Turbines Foundation covers the foundations of the machines: the comparison of foundation types, the selected scheme and the demonstration of its feasibility, a subject developed further in the special research report of Appendix B.

13.5 Onshore Step-Up Substation or Centralized Control Center covers the civil design of the onshore installation, whether it takes the form of a step-up substation or of a centralized control centre.

13.6 Offshore Step-Up Substation covers the civil design of the offshore step-up substation, including its structure, its foundation and its topside arrangement.

13.7 Corrosion Prevention Design covers protection of the structures against corrosion in the marine environment, over the design life of the wind farm.

13.8 Scour Protection Design covers protection of the foundations against seabed scour, on the basis of the sediment conditions reported under sub-clause 7.6.

13.9 Ship Berthing and Anti-collision Design covers the berthing arrangements for service vessels and the protection of the structures against ship impact.

13.10 Anti-Icing Design covers the design measures against sea ice, required where the sea ice conditions reported under sub-clause 7.5 make them necessary.

13.11 Monitoring Design covers the monitoring of the structures, that is, the instruments and the observation arrangements provided to follow their behaviour in service.

13.12 Civil Design of Transmission Lines covers the civil design of the transmission lines associated with the project.

13.13 Tables and Figures lists the civil works tables and drawings to be attached to the chapter.

14 Construction Organization Design

Clause 14, Construction Organization Design, spans pages 39 to 43 and prescribes the chapter dealing with how the wind farm is to be built. It is divided into nine sub-clauses and is developed further in the special research report of Appendix C.

14.1 General states the scope and the basis of the construction organization design.

14.2 Construction Conditions covers the conditions under which construction will take place, including the natural conditions at sea, the workable weather windows and the resources locally available.

14.3 Construction Transportation covers the transport of plant and materials, by sea and by land, and the access arrangements to the site.

14.4 Cofferdam and Platform covers the temporary cofferdams and working platforms required by marine construction.

14.5 Main Works Construction covers the construction of the permanent works themselves: the wind turbine foundations, the erection of the machines, the offshore step-up substation and the laying of the submarine cables.

14.6 Construction General Layout covers the general layout of the construction works, including the onshore assembly and storage areas and the port facilities used.

14.7 General Construction Progress covers the construction programme and the overall schedule of the project.

14.8 Construction Material Supply covers the supply of the resources required by construction, including materials, equipment, vessels, power and water.

14.9 Figures lists the construction drawings to be attached to the chapter.

15 Sea and Land Use for Project Construction

Clause 15, Sea and Land Use for Project Construction, spans pages 44 and 45 and prescribes the chapter on the sea area and the land occupied by the project. It is divided into three sub-clauses.

15.1 Sea Use covers the sea area required by the project, the classification and extent of that use, its compatibility with the marine functional zoning and with the other users of the area, and the approvals involved.

15.2 Land Use covers the land required by the project on shore, both permanently and temporarily, for the substation or control centre, the cable landing and the construction facilities.

15.3 Figures lists the sea use and land use drawings to be attached to the chapter.

16 Environmental Protection and Soil and Water Conservation

Clause 16 spans pages 46 to 48 and prescribes the environmental chapter of the feasibility study report. It is divided into three sub-clauses.

16.1 Environmental Impact Assessment covers the environmental background of the project, the identification of the impacts of construction and operation on the marine and coastal environment and the conclusions of the environmental impact assessment.

16.2 Environmental Protection Design covers the protection measures designed into the project, together with their investment estimate.

16.3 Soil and Water Conservation Design covers the soil and water conservation measures required by the works, principally on the onshore parts of the project, and their investment estimate.

17 Occupational Health and Safety

Clause 17, Occupational Health and Safety, spans pages 49 to 51 and prescribes the labour safety and occupational health chapter of the feasibility study report. It is divided into eight sub-clauses.

17.1 General states the basis and the scope of the safety and health chapter.

17.2 Analysis on Main Hazards and Harmful Factors requires the identification and analysis of the hazards and harmful factors present in an offshore wind farm, during construction as well as during operation and maintenance.

17.3 Safety and Health Design covers the safety and occupational health measures designed into the works.

17.4 Set-Up of Safety Management Organizations, Design of Related Facilities and Safety Management covers the safety management organization to be established, the facilities that support it and the management arrangements adopted.

17.5 Special Investment Estimation for Occupational Health and Safety requires the separate estimate of the investment devoted to labour safety and occupational health.

17.6 Adoption of Recommendations and Measures Raised by Safety Pre-assessment Report requires the report to state how the recommendations and measures raised by the safety pre-assessment report have been taken up in the design.

17.7 Main Conclusion and Recommendations requires the conclusions of the chapter and the recommendations arising from it.

17.8 Tables lists the safety and occupational health tables to be attached to the chapter.

18 Energy Saving

Clause 18, Energy Saving, spans pages 52 to 54 and prescribes the energy saving chapter of the feasibility study report. It is divided into five sub-clauses.

18.1 Preparation Basis and Basic Data states the basis on which the energy saving analysis is prepared and the data it uses.

18.2 Analysis of Energy Consumption Types and Quantities and Energy Consumption Indicators in Operation Period requires the analysis of the types and quantities of energy consumed by the wind farm in service and the derivation of the corresponding energy consumption indicators.

18.3 Main Energy-Saving Measures covers the energy saving measures adopted in the design of the project.

18.4 Analysis of Energy-Saving Benefits requires the analysis of the benefits obtained from those measures.

18.5 Conclusion and Recommendations requires the conclusions of the energy saving chapter and the recommendations arising from it.

19 Cost Estimation

Clause 19, Cost Estimation, occupies page 55 and prescribes the chapter presenting the cost estimate of the project at feasibility study stage.

The chapter covers the basis and the price level of the estimate, the composition of the estimated cost of the works, the estimate tables and the total investment required by the project, which is the input to the financial evaluation of the following chapter.

20 Financial Evaluation and Social Effect Analysis

Clause 20 spans pages 56 and 57 and prescribes the economic chapter of the feasibility study report. It is divided into five sub-clauses.

20.1 General states the basis and the parameters of the financial evaluation.

20.2 Financial Evaluation requires the evaluation proper, that is, the calculation of the financial indicators of the project on the basis of the estimated investment, the energy output and the tariff.

20.3 Attached Tables for Financial Evaluation lists the financial tables that must accompany the evaluation.

20.4 Risk Analysis requires the analysis of the risks affecting the economic result, including the sensitivity of the indicators to the main variables.

20.5 Social Effect Evaluation requires the evaluation of the effects of the project on society, including its contribution to energy supply, to emission reduction and to local development.

21 Bidding

Clause 21, Bidding, occupies page 58 and closes the body of the specification. It is divided into three sub-clauses.

21.1 General states the basis of the bidding chapter of the feasibility study report.

21.2 Bidding Scope and Content covers the scope of the bidding, that is, the works, equipment and services to be tendered, and the content of each package.

21.3 Bidding Planning covers the bidding arrangements and programme proposed for the project.