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GB/T 20996.2-2020Performance of high-voltage direct current (HVDC) systems with line-commutated converters - Part 2: Faults and switching (English PDF)

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Issued by

State Administration for Market Regulation, China National Standardization Administration

Level / Type

National · Recommended

Issue date

December 14, 2020

Implementation date

July 1, 2021

Scope

GB/T 20996.2-2020 (Performance of high-voltage direct current (HVDC) systems with line-commutated converters - Part 2: Faults and switching) is available as an English-translated PDF.

GB/T 20996.2-2020 — This part of GB/T 20996 is a guidance document on the transient performance and fault protection requirements of HVDC systems; it discusses the three-phase bridge The transient performance of the fault and operation of the high-voltage DC system at both ends of the 12-pulse (dynamic) converter unit connected by the type (dual circuit) connection does not involve multi-terminal high DC transmission system, but the parallel converter and parallel circuit included in the two-end system are discussed; it is assumed that the converter uses thyristor valves As the bridge arm, a gapless metal oxide arrester is used for insulation coordination, and the power can be transmitted in both directions: Two poles are not considered in this section Pipe valve: This section only involves power grid commutated converters, including converters with capacitor commutated circuit structures: In IEC 60146-1-1, IEC 60146-1- 2 and IEC 60146-1-31) give the general requirements for power grid commutated semiconductor converters: This section does not consider voltage source converters: GB/T 20996 is composed of three parts: steady state, fault and operation, and dynamic: In the process of formulation and writing, three Duplication of part of the content: Therefore, when the user is preparing to compile the specifications of the two-terminal HVDC system, the entire content of the three parts should be referred to: For each component in the system, pay attention to the difference between system performance specifications and equipment design specifications: This section does not provide technical specifications for equipment Make provisions with test requirements, but focus on those technical requirements that affect system performance: This section also does not include detailed seismic performance requirements: In addition, different HVDC systems may have many differences, which are not discussed in detail in this section: Therefore, this section should not directly Used as a technical specification for a specific engineering project: However, it can be used as a basis to compile specific transmission systems to meet actual system requirements Technical specifications: The content involved in this section does not distinguish between the responsibilities of the user and the manufacturer: Since the equipment of each DC project is usually designed and purchased independently, considering the impact on the performance of the HVDC system, this section includes DC Lines, grounding pole lines and grounding poles: For ease of use, this section assumes that the HVDC converter station includes converters and valve halls, reactors, filters, reactive power compensation devices, control Control system, monitoring system, measuring device, protection device and auxiliary system: This part does not include those other than AC filters and reactive power compensation devices Other communication equipment:

Document preview — GB/T 20996.2-2020

National Standard of the People's Republic of China

ICS
29.200; 29.240.99
Classification
K 46
Replacing
GB/Z 20996.2-2007

Issued by: State Administration for Market Regulation, China National Standardization Administration

Contents

  • 1 Scope1
  • 2 Normative references1
  • 3 Overview of technical specifications for HVDC transient performance2
  • 3:1 Technical specifications for transient performance2
  • 3:2 General provisions2
  • 4 Transient process of trouble-free operation2
  • 4:1 Overview2
  • 4:2 Power-on and power-off of equipment on the AC side3
  • 4:3 Load shedding4
  • 4:4 Start-up and shutdown of inverter unit5
  • 4:5 Operation of DC circuit breaker and DC switch5
  • 5 AC system failure7
  • 5:1 Overview7
  • 5:2 Failure Type7
  • 5:3 Related matters affecting transient performance specifications7
  • 5:4 The impact of technical specifications on control strategies10
  • 6 AC filter, reactive power compensation device and AC bus failure11
  • 6:1 Overview11
  • 6:2 Transient overvoltage of the filter bank11
  • 6:3 Transient overcurrent of filter and capacitor bank12
  • 6:4 Capacitor unbalance protection12
  • 6:5 Examples of filter and capacitor bank protection13
  • 6:6 Shunt reactor protection13
  • 6:7 AC bus protection13
  • 7 Inverter unit failure15
  • 7:1 Overview15
  • 7:2 Short circuit16
  • 7:3 Expected malfunction of inverter unit17
  • 7:4 Inverter unit protection17
  • 7:5 Additional protection of series converter units18
  • 7:6 Additional protection of parallel converter units19
  • 8 Failure of smoothing reactor, DC filter and other DC equipment20
  • 8:1 Overview20
  • 8:2 Failure types20
  • 8:3 Protected areas21
  • 8:4 Neutral bus protection21
  • 8:5 Smoothing reactor protection22
  • 8:6 DC filter protection22
  • 8:7 DC harmonic protection23
  • 8:8 DC overvoltage protection23
  • 8:9 DC side switch protection23
  • 9 DC line failure24
  • 9:1 Overhead line fault24
  • 9:2 Cable fault25
  • 9:3 Characteristics of DC faults25
  • 9:4 Functional requirements for DC line fault detection25
  • 9:5 Protection processing25
  • 9:6 Fault protection scheme26
  • 9:7 Open circuit on DC side26
  • 9:8 AC/DC line cross protection27
  • 10 Ground electrode line fault27
  • 10:1 Overview27
  • 10:2 Special requirements for grounding electrode lines27
  • 10:3 Earth electrode circuit monitoring27
  • 11 Metal loop circuit fault28
  • 11:1 Metal loop28
  • 11:2 Metal circuit failure28
  • 11:3 Metal circuit fault detection28
  • 11:4 Metal circuit fault protection system29
  • 12 Insulation coordination of HVDC systems31
  • 12:1 Overview31
  • 12:2 Protection scheme using lightning arrester31
  • 12:3 AC side operating overvoltage and temporary overvoltage32
  • 12:4 DC side operating overvoltage and temporary overvoltage32
  • 12:5 Lightning and steep wave impact32
  • 12:6 Protection margin32
  • 12:7 Lightning arrester function33
  • 12:8 Prevent the arrester current from causing relay protection action35
  • 12:9 Insulation spacing35
  • 12:10 Insulation creepage35
  • 13 Communication requirements38
  • 13:1 Overview38
  • 13:2 Special requirements for communication systems38
  • 13:3 Consequences of a communication system interruption39
  • 13:4 Special considerations for power line carrier (PLC) systems39
  • 14 Auxiliary system39
  • 14:1 Overview39
  • 14:2 Electrical auxiliary system39
  • 14:3 Mechanical auxiliary system40
  • References42

Foreword

GB/T 20996 "Performance of HVDC System Using Grid Commutation Converter" is divided into 3 parts:

---Part 1: Steady state;

---Part 2: Failure and operation;

---Part 3: Dynamics:

This part is Part 2 of GB/T 20996:

This section was drafted in accordance with the rules given in GB/T 1:1-2009:

This part replaces GB /Z 20996:2-2007 "Performance of High Voltage Direct Current System Part 2: Failure and Operation", and

Compared with GB /Z 20996:2-2007, the main technical changes are as follows:

--- Change the "General Provisions" to "Scope" and "Normative Reference Documents" (see Chapter 1, Chapter 2, Chapter 1 of the:2007 edition);

---Modified the scope (see Chapter 1, 1:1 of the:2007 edition);

---Modified the normative references (see Chapter 2, 1:2 of the:2007 edition);

--- The title of the article "Institution and removal of equipment on the AC side" is revised to "Power on and off equipment on the AC side" (see 4:2,:2007 edition)

3:2);

--- Modified the description of transformer magnetizing inrush current (see 4:2,:2007 edition 3:2);

---Added the opening operation recommendations of the converter transformer, the definition of the highest tapping position of the transformer, the

The description of the charging of the container and the filter bank (see 4:2);

---Added setting suggestions that help remote circuit breaker tripping (see 4:3, 3:3 in:2007 edition);

---Modified the provisions of DC switchgear (see 4:5, 3:5 in:2007 edition);

--- Modified the description of grounding and grounding faults in HVDC converter stations (see 5:2, 4:2 in:2007 edition);

---Added the conditions to be considered for the transient characteristics of DC equipment during AC failure and after recovery (see 5:2, 4:2 in:2007 edition);

--- Deleted the content of the suspended paragraph in the "Relevant Matters Affecting Transient Performance Specifications" (see 4:3 in the:2007 edition);

---Added the description of the measures that can be taken to reduce the commutation failure (see 5:3:2, 4:3:2 of the:2007 edition);

--- Deleted "If the removed reactive power equipment must be renewed before the load of the HVDC system reaches the level before the failure

Investment, this kind of reactive power equipment switching method will cause the restart time of the high voltage DC system to be too long, which is another consideration that needs to be considered:

Questions: "(See 4:3:6 of the:2007 edition);

---Added the precautions when using digital and old type relay protection devices (see 5:3:7);

---Modified the expression of the example of the arrangement of AC filters and shunt capacitors in the bipolar high voltage DC system (see 6:1,:2007 edition

5:1);

--- "The analysis should take into account the system structure that causes the most severe stress: The system includes filters and shunt capacitors:" Amend to

"The most severe stress caused by the system structure including filters and shunt capacitors should be considered in the analysis:" (see 6:3,:2007

5:3 of the year edition);

---Added the description of the bridge wiring of the capacitor bank "H" (see 6:4);

---Added the consideration principle for the circuit breaker failure in the valve design and the design considerations of the arrester at both ends of the commutation capacitor

(See 7:2);

--- The title of the article "function failure of inverter unit" is revised to "expected function failure of inverter unit" (see 7:3,:2007 edition

6:4);

--- Modify the "Gate Pulse" to "Trigger Pulse", and the subsequent text in the full text has also been modified accordingly (see 7:3:2,:2007 edition

6:4:1);

--- "If the specified time is exceeded or the commutation failure is caused by the missing gate pulse, then the converter should be blocked:" Amend to

"If the specified time is exceeded or the commutation fails due to the missing trigger pulse, the inverter should be locked:" (see 7:3:3,

6:4:2 of the:2007 edition);

---Added a recommendation for the actual system protection settings to eliminate the protection blind zone (see 8:3,:2007 edition 7:3);

---Added the proposal of laying spare cables, cable joints and their switchgear and protection configuration when using coaxial cables (see

9:2);

---Added provisions on the frequency of detection of faults by metal loop fault location equipment (see 11:3);

---Added the operating regulations for disconnecting the DC circuit breaker after the arc is extinguished (see 11:4);

---Added HVDC converter station with series capacitor compensation and UHV DC transmission system with series connected converters:

The description of the minecraft configuration plan (see 12:2, 12:7:1);

--- Modify the "DC reactor" in the full text to "Smoothing reactor", and make the corresponding modifications to the diagram in the text;

---Added "Different from AC stations, the insulation level (SIWV, LIWV) of high-voltage DC equipment does not have to take standard values:" (see 12:6);

--- Modify "discharge current of valve hall capacitor;" to "discharge of valve hall capacitor;" and "lightning wave discharge current" amended to "lightning wave discharge

Electricity" (see 12:7:3, 11:7:3 of the:2007 edition);

--- Added "In addition, in addition to the above measures to deal with pollution, composite insulators are also one of the options:" (see 12:10:1);

---Added regulations on the cleaning of the valve hall (see 12:10:2);

---Added "Communication can also be used for line fault location, and can distinguish cable faults and overhead line faults:" (see 13:2);

---Added provisions for designing hot standby or redundant equipment (see 14:3):

The translation method used in this part is equivalent to the IEC TR60919-2:2020 "Performance of HVDC System Using Grid Commutation Converter"

Part 2: Failure and Operation":

The Chinese documents that have a consistent correspondence with the international documents cited in this section are as follows:

---GB/T 311:1-2012 Insulation coordination Part 1: Definitions, principles and rules (IEC 60071-1:2006, MOD)

---GB/T 3859:1-2013 General requirements for semiconductor converters and power grid commutated converters Part 1-1: Basic requirements

Fan (IEC 60146-1-1:2009, MOD)

---GB/T 3859:2-2013 General requirements for semiconductor converters and power grid commutated converters Part 1-2: Application guidelines

(IEC TR60146-1-2:2011, MOD)

---GB/T 3859:3-2013 General requirements for semiconductor converters and power grid commutated converters Part 1-3: Transformers and electricity

Reactor (IEC 60146-1-3:1991, MOD)

---GB/T 13498-2017 Terminology for HVDC Transmission (IEC 60633:2015, MOD)

---GB/T 20990:1-2020 HVDC Thyristor Valve Part 1: Electrical Test (IEC 60700-1:2015,

MOD)

---GB/T 20996:1-2020 Performance of HVDC systems using grid-commutated converters Part 1: Steady state

(IEC TR60919-1:2017, IDT)

---GB/T 20996:3-2020 Performance of HVDC systems using grid-commutated converters Part 3: Dynamics

(IEC TR60919-3:2016, IDT)

This section has made the following editorial changes:

---In Figure 2, modify "when lo rises linearly or exponentially: tauR=20ms,tau1=10ms" to "when Io rises linearly or exponentially:

tauR=10ms,tau1=20ms";

--- In Figure 14, modify "If" to "It", "In-If" to "Id-It", and "In-In" to "It-In":

This part was proposed by China Electrical Equipment Industry Association:

This part is under the jurisdiction of the National Power Electronic System and Equipment Standardization Technical Committee (SAC/TC60):

Drafting organizations of this section: China Electric Power Research Institute Co:, Ltd:, China Southern Power Grid Research Institute Co:, Ltd:, Xi'an High Voltage

Research Institute Co:, Ltd:, Xi'an Power Electronics Technology Research Institute, Global Energy Internet Research Institute Co:, Ltd:, Tsinghua University, South China

Jingnan Ruijibao Electric Co:, Ltd:, Xi'an Xidian Power System Co:, Ltd:, Xu Ji Electric Co:, Ltd:, China Southern Power Grid Co:, Ltd:

Served as the company's ultra-high voltage transmission company, State Grid Economic and Technical Research Institute Co:, Ltd:, Xi'an Duanyi Technology Co:, Ltd:, Pinggao Group

Power Research Institute of Anhui Electric Power Co:, Ltd:

1 Scope

This part of GB/T 20996 is a guidance document on the transient performance and fault protection requirements of HVDC systems; it discusses the three-phase bridge

The transient performance of the fault and operation of the high-voltage DC system at both ends of the 12-pulse (dynamic) converter unit connected by the type (dual circuit) connection does not involve multi-terminal high

DC transmission system, but the parallel converter and parallel circuit included in the two-end system are discussed; it is assumed that the converter uses thyristor valves

As the bridge arm, a gapless metal oxide arrester is used for insulation coordination, and the power can be transmitted in both directions: Two poles are not considered in this section

Pipe valve:

This section only involves power grid commutated converters, including converters with capacitor commutated circuit structures: In IEC 60146-1-1, IEC 60146-1-

2 and IEC 60146-1-31) give the general requirements for power grid commutated semiconductor converters: This section does not consider voltage source converters:

GB/T 20996 is composed of three parts: steady state, fault and operation, and dynamic: In the process of formulation and writing, three

Duplication of part of the content: Therefore, when the user is preparing to compile the specifications of the two-terminal HVDC system, the entire content of the three parts should be referred to:

For each component in the system, pay attention to the difference between system performance specifications and equipment design specifications: This section does not provide technical specifications for equipment

Make provisions with test requirements, but focus on those technical requirements that affect system performance: This section also does not include detailed seismic performance requirements:

In addition, different HVDC systems may have many differences, which are not discussed in detail in this section: Therefore, this section should not directly

Used as a technical specification for a specific engineering project: However, it can be used as a basis to compile specific transmission systems to meet actual system requirements

Technical specifications: The content involved in this section does not distinguish between the responsibilities of the user and the manufacturer:

Since the equipment of each DC project is usually designed and purchased independently, considering the impact on the performance of the HVDC system, this section includes DC

Lines, grounding pole lines and grounding poles:

For ease of use, this section assumes that the HVDC converter station includes converters and valve halls, reactors, filters, reactive power compensation devices, control

Control system, monitoring system, measuring device, protection device and auxiliary system: This part does not include those other than AC filters and reactive power compensation devices

Other communication equipment:

2 Normative references

The following documents are indispensable for the application of this document: For dated reference documents, only the dated version applies to this article

Pieces: For undated references, the latest version (including all amendments) applies to this document:

IEC 60071-1 Insulation coordination Part 1: Terms, definitions, principles and rules (Insulationco-ordination-Part 1:

Terms,Definitions,principlesandrules)

IEC 60146-1-1 General requirements for semiconductor converters and grid-commutated converters Part 1-1: Basic requirements specification (Semi-

conductorconverters-Generalrequirementsandlinecommutatedconverters-Part 1-1:Specification

ofbasicrequirements)

1) IEC 60146-1-3 has been abolished and is covered by IEC 61378 series and IEC /IEEE60076-57-129:

IEC 60146-1-2 General requirements for semiconductor converters and grid-commutated converters Part 1-2: Application guidelines (Semiconductor

converters-Generalrequirementsandlinecommutatedconverters-Part 1-2:Applicationguide)

IEC TR60146-1-31) General requirements for semiconductor converters and grid-commutated converters Part 1-3: Transformers and reactors

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — all pages — is available in the English PDF.

Referenced standards

Normative references

IEC 60071 · IEC 60146 · IEC 61378

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