NB/T 31026-2022Code for electrical design of wind power projects (English PDF)

Foreword

This document was issued on 13 May 2022 by the National Energy Administration of the PRC and takes effect on 13 November 2022.

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It replaces NB/T 31026-2012, which is superseded.

This code has been revised in accordance with the requirements of the Notice of the General Affairs Department of the National Energy Administration on Issuing the 2017 Plan for the Development and Revision of Industry Standards in the Energy Field and the Plan for the Translation and Publication of Their English Versions (Guo Neng Zong Tong Ke Ji [2017] No. 52). The drafting group carried out extensive investigation and research, earnestly summarized practical experience, and revised the code on the basis of a wide solicitation of opinions.

The main technical contents of this code are: general provisions; terms; basic requirements; connection to the power system; electrical primary system; electrical secondary system; communication; power collection line; and electrical equipment layout together with the requirements for civil works.

The main technical contents revised in this edition are listed in the paragraphs below.

The scope of application has been changed to read: this code is applicable to wind power projects that are connected to the power system at a voltage level of 66 kV and above.

Provisions governing the electrical design of offshore wind power projects have been added.

The terms 'wind turbine transformer', 'wind turbine high voltage ride through capability', 'dynamic reactive power compensation device', 'array submarine cable' and 'export submarine cable' have been added.

Contents dealing with 'dispatching automation', the 'online monitoring system' and the 'communication power supply' have been added.

Contents such as the configuration principles for the 'image surveillance and security system' and for the 'automatic fire alarm system' have been added.

The contents of the 'monitoring and control system' and of the 'relay protection and safety automatic devices' have been revised.

The configuration principles of the 'AC/DC control power supply system' have been revised.

The terms and definitions of 'wind farm', 'wind turbine generator system', 'reactive power compensation device', 'static var compensator', 'centralized monitoring and control system' and 'monitoring and control system' have been deleted.

This code is administered by the National Energy Administration. It is proposed by, and placed under the day-to-day administration of, the China Renewable Energy Engineering Institute, while the Sub-technical Committee on Wind Farm Planning and Design of the Energy Industry Wind Power Standardization Technical Committee (NEA/TC1/SC1) is responsible for the interpretation of its specific technical contents. Comments and suggestions arising during implementation should be sent to the China Renewable Energy Engineering Institute, No. 2 Liupukang Beixiaojie, Xicheng District, Beijing, postcode 100120.

Publication and Approval Data

Standard designation: NB/T 31026-2022, an energy industry standard of the People's Republic of China. The Chinese title printed on the cover is 风电场工程电气设计规范 and the official English title printed beneath it is 'Code for Electrical Design of Wind Power Projects'.

Classification data shown on the cover: ICS 27.180 and the Chinese Standard Classification code P 61, with the sector letter P printed on the left of the cover band and the sector mark NB in the upper right corner.

Date of issue: 13 May 2022. The cover carries the issue statement 2022-05-13 and the issuing authority is the National Energy Administration.

Date of implementation: 13 November 2022. The cover carries the implementation statement 2022-11-13, and the inside title page repeats the effective date as 13 November 2022.

Replaced standard: this edition supersedes NB/T 31026-2012, as stated on the cover and repeated on the inside title page.

Inside title page data: the chief editing department is the China Renewable Energy Engineering Institute; the approving department is the National Energy Administration; the date of entry into force is 13 November 2022.

Publication data: the code is published by China Water and Power Press, Beijing, 2022.

The code was released by Announcement No. 4 of 2022 of the National Energy Administration, dated 13 May 2022.

That announcement states that, pursuant to the Standardization Law of the People's Republic of China and the Measures for the Administration of Energy Standardization, the National Energy Administration approved 209 energy industry standards headed by the Technical Guideline for Smart Wind Farms (Annex 1), the foreign-language versions of 23 energy industry standards headed by the Specification for Preparation of Feasibility Study Report for Photovoltaic Power Projects (Annex 2), and amendment notices to 2 energy industry standards headed by the Code of Investigation for Natural Construction Materials of Hydropower Projects (Annex 3).

In the catalogue of industry standards attached to that announcement as Annex 1, this code appears as item 69 with the designation NB/T 31026-2022, the title 风电场工程电气设计规范, the replaced standard NB/T 31026-2012, the approval date 2022-05-13 and the implementation date 2022-11-13.

Structure of the Code

The code is organized in nine chapters followed by five appendices, an explanation of the wording used in the code, a list of quoted standards and an addition containing the explanation of the provisions. The main text runs to page 51, the appendices occupy pages 52 to 64, and the back matter begins on page 65, with the explanation of provisions starting on page 69.

Chapter 1, General Provisions, occupies page 1.

Chapter 2, Terms, begins on page 2.

Chapter 3, Basic Requirements, begins on page 4.

Chapter 4, Connection to Power System, begins on page 5.

Chapter 5, Electrical Primary System, begins on page 6 and is divided into eleven sections.

The first sections of Chapter 5 are 5.1 Main Electrical Connection, on page 6; 5.2 Wind Turbine, on page 7; 5.3 Wind Turbine Transformer, on page 12; 5.4 Main Transformer, on page 13; 5.5 High-Voltage Switchgear Installation, on page 14; and 5.6 Conductors and Electrical Equipment, also on page 14.

The remaining sections of Chapter 5 are 5.7 Reactive Power Compensation Device, on page 16; 5.8 Service Power System, on page 17; 5.9 Cable Selection and Laying, on page 18; 5.10 Overvoltage Protection and Earthing, on page 19; and 5.11 Lighting, on page 20.

Chapter 6, Electrical Secondary System, begins on page 22 and is divided into nine sections.

The sections of Chapter 6 are 6.1 General Requirements, on page 22; 6.2 Dispatching Automation, on page 23; 6.3 Monitoring and Control System, on page 27; 6.4 Relay Protection and Safety Automatic Devices, on page 30; 6.5 AC/DC Control Power Supply System, on page 33; 6.6 Image Surveillance and Security System, on page 35; 6.7 Automatic Fire Alarm System, on page 36; 6.8 Online Monitoring System, on page 37; and 6.9 Secondary Circuit, on page 38.

Chapter 7, Communication, begins on page 40 and is divided into six sections: 7.1 General Requirements and 7.2 System Communication, both on page 40; 7.3 On-site Communication, on page 41; 7.4 Communication Power Supply and 7.5 Generic Cabling, both on page 42; and 7.6 Others, on page 43.

Chapter 8, Power Collection Line, begins on page 44 and is divided into two sections: 8.1 General Requirements and 8.2 Overhead Power Collection Line Design, both beginning on page 44.

Chapter 9, Electrical Equipment Layout and the Requirements for Civil Works, begins on page 47 and is divided into seven sections: 9.1 General Requirements and 9.2 Wind Turbine Transformer, both on page 47; 9.3 Main Transformer, 9.4 High-Voltage Switchgear Installation and 9.5 Cable Structures, all on page 48; 9.6 Secondary Equipment Layout, on page 50; and 9.7 Central Control Room and Others, on page 51.

Appendix A, Connection at Low-Voltage Side of Main Transformer, begins on page 52, and Appendix B, Arrangement for High-Voltage Leads of Wind Turbine Transformer, begins on page 57.

Appendix C, Telecontrol Information, begins on page 59; Appendix D, Typical Structure Diagram of Monitoring System, begins on page 62; and Appendix E, Online Monitoring Configuration of Step-up Substation, begins on page 64.

The back matter comprises the Explanation of Wording in This Code, on page 65; the Lists of Quoted Standards, on page 66; and the Addition, Explanation of Provisions, on page 69.

Drafting and Review Organizations

The chief drafting organization of this code is PowerChina Northwest Engineering Corporation Limited.

The participating drafting organizations are PowerChina Huadong Engineering Corporation Limited, China Energy Engineering Group Guangdong Electric Power Design Institute Co., Ltd., and Shanghai Investigation, Design and Research Institute Co., Ltd.

The foreword lists twenty-five chief drafters of the code, headed by Li Hui, Xi Yu, Shen De and Zhang Guoqiang.

The foreword lists sixteen chief reviewers of the code, headed by Xie Hongwen, Wei Huixiao, Fang Hui and Yue Lei.

Administration of the code rests with the National Energy Administration; the China Renewable Energy Engineering Institute proposes the code and handles its day-to-day administration, and NEA/TC1/SC1 interprets its specific technical contents.

1 Scope

NB/T 31026-2022 is the Chinese code for the electrical design of wind farm projects, replacing the 2012 edition. It covers everything electrical between the turbine terminals and the point of connection to the grid. The code sets the general provisions and the basic requirements, then the electrical system design: the choice of voltage levels, the collection system arrangement in radial or ring configuration, the load flow, short circuit and reactive power studies, the power quality assessment and the reactive compensation and voltage control equipment needed to meet the grid code. It then covers the equipment itself - the step-up transformers at each turbine, the collection cables both buried and overhead with their sizing, laying and protection, the step-up substation with its main transformers, switchgear, busbars and auxiliary supplies, the standby power, and the earthing and lightning protection of the whole installation. Protection and control have their own chapters: the relay protection scheme, the automation and SCADA system, metering, communications to the dispatch centre, and the fault recording and power quality monitoring. Cable routing, building electrical services, lighting and the DC and UPS systems complete the plant. The code closes with the drawings and calculations that must form part of the design submission. It applies to onshore wind power projects in China at every design stage.

Chapter 1 of the code sets out its purpose, its scope of application and its relationship with other standards. It consists of three provisions, numbered 1.0.1 to 1.0.3, and occupies page 1 of the code.

1.0.1 This code is formulated in order to standardize the electrical design of wind power projects.

1.0.2 This code is applicable to wind power projects that are connected to the power system at a voltage level of 66 kV and above.

1.0.3 In addition to complying with this code, the electrical design of wind power projects shall also comply with the provisions of the relevant standards currently in force in China.

2 Terms

Chapter 2 defines nine terms, numbered 2.0.1 to 2.0.9, each given with its Chinese designation and its English equivalent. The chapter occupies pages 2 and 3 of the code.

2.0.1 wind turbine transformer (风电机组变电单元): the transformer provided for a wind turbine generator system, together with its high-voltage and low-voltage distribution equipment.

2.0.2 wind turbine low voltage ride through capability (风电机组低电压穿越能力): the capability of a wind turbine generator system to remain connected to the grid and to continue operating without tripping, within a defined range of voltage dip and within a defined time interval, when a fault or a disturbance in the power grid causes the voltage to fall.

2.0.3 wind turbine high voltage ride through capability (风电机组高电压穿越能力): the capability of a wind turbine generator system to remain connected to the grid and to continue operating without tripping, within a defined range of voltage rise and within a defined time interval, when a fault or a disturbance in the power grid causes the voltage to rise.

2.0.4 dynamic reactive power compensation device (动态无功补偿装置): a device connected in parallel to a wind farm whose capacitive or inductive reactive output current is continuously adjustable within a defined voltage range, so as to achieve reactive power compensation or voltage control at the regulating point.

2.0.5 power collection line (集电线路): the line used inside a wind farm to collect the electrical energy generated by several wind turbine generator systems and to convey it to the step-up substation.

2.0.6 array submarine cable (集电线路海底电缆): the submarine cable used to collect the electrical energy generated by offshore wind turbine generator systems and to convey it to the step-up substation.

2.0.7 export submarine cable (送出线路海底电缆): the submarine cable connecting an offshore step-up substation with the onshore power grid.

2.0.8 monitoring and control center for wind power plant and substation (集控中心): the centre that controls and monitors equipment such as the wind turbine generator systems, the wind turbine transformers, the power collection lines and the associated step-up substation.

2.0.9 monitoring and control center for wind power plant (监控中心): the centre that controls and monitors equipment such as the wind turbine generator systems, the wind turbine transformers and the power collection lines.

3 Basic Requirements

Chapter 3 states the general design principles applying to the whole code. It consists of four provisions, numbered 3.0.1 to 3.0.4, and occupies page 4 of the code.

3.0.1 The electrical design of a wind power project shall implement the technical and economic policies of the State and shall meet the requirements of the development plan. The electrical design scheme shall be established according to the specific conditions of the project, including the requirements of the power system in which the wind farm is located, the operating mode of the wind farm, its output characteristics, the layout conditions and the features of the natural environment.

3.0.2 The electrical design of a wind power project shall proceed from actual conditions and shall take the characteristics of the region into account. It shall adhere to the basic principles of economizing on the use of land and of sea areas and of protecting the environment, and shall actively adopt new technologies, new processes, new materials and new equipment.

3.0.3 The electrical design of a wind power project shall give full consideration to the requirements of equipment installation, testing, operation, overhaul and maintenance.

3.0.4 The electrical design of a wind power project shall be combined with the overall planning of the project so as to coordinate the relationship between construction in the near term and development in the long term.

4 Connection to Power System

Chapter 4 deals with the connection of the wind power project to the power system. It consists of four provisions, numbered 4.0.1 to 4.0.4, the last of which contains five itemized requirements. The chapter occupies page 5 of the code.

4.0.1 The design for the connection of a wind power project to the power system shall comply with the relevant provisions of the national standards currently in force: Technical Regulations for Connecting Wind Farm to Power System, Part 1: On Shore Wind Power, GB/T 19963.1; Technical Code for Designing of Large Scale Wind Farm Grid Integration, NB/T 31003; and Technical Code for Designing of Power System, DL/T 5429.

4.0.2 The electrical design of a wind power project shall satisfy the requirements of the connection to the power system.

4.0.3 Where a wind farm is built in separate zones or in successive stages, the layout of the step-up substation and of the monitoring and control center for wind power plant and substation, or of the monitoring and control center for wind power plant, shall be planned rationally according to the sequence of development.

4.0.4 The following data concerning the connection to the power system shall be collected for the electrical design of a wind farm.

Item 1 of provision 4.0.4: the geographical connection diagram of the existing system and the geographical connection diagrams for each planning year; the sequence impedance values; and the results of the power flow, stability and short-circuit current calculations.

Item 2 of provision 4.0.4: the voltage level of the outgoing lines, the number of circuits, the cross-section of the conductors, the landing point of each outgoing circuit and the transmission capacity.

Item 3 of provision 4.0.4: the requirements of the system regarding the main performance parameters of the main transformer, such as its type, rated voltage and short-circuit impedance, and regarding the voltage regulating range and mode and the neutral point earthing mode.

Item 4 of provision 4.0.4: the requirements of the system regarding the main performance parameters of equipment such as the wind turbine generator systems, the reactive power compensation devices and the shunt reactors.

Item 5 of provision 4.0.4: the requirements of the system regarding the dispatching management and automation of the wind farm, the system relay protection and safety automatic devices, and the system communication.