4　General Requirements

4.0.1　System design

For converter station system design in an HVDC transmission system，the system shall be considered integrally to achieve optimized overall performance.With reference to IEC 60919-3，the following main tasks shall be completed in system design:

1　Main circuit design.

（1）Study on connection and operation modes of HVDC transmission system.

（2）Study on basic operation control strategy for HVDC transmission system and main circuit parameters.

（3）Study on load capacity of key equipment.

2　Reactive power compensation and control.

（1）Study on reactive power compensation and reactive power balance.

（2）Study on reactive power compensation scheme for converter station.

（3）Study on reactive power control strategy.

3　Transient performance design.

（1）Study on overvoltage and insulation coordination.

（2）Study on temporary overvoltage and ferro-resonance overvoltage.

（3）Study on transient current.

4　DC system performance design.

（1）Study on flow stability of AC systems connected at both terminals and modulation control.

（2）Study on islanded operation mode（if required）.

（3）Study on performance of interconnected AC and DC system（if required）.

（4）Study on interaction among multiple DC circuits in a grid（if required）.

（5）Study on dynamic performance to determine control functions and parameters of converter.

（6）Study on converter station loss.

（7）Study on audible sound level of converter station.

（8）Study on availability and reliability.

5　Calculation of DC biasing current on converter transformer.

6　Study on functional configuration and parameters of converter transformer on-load tap changer.

7　Filter design.

（1）Study on AC filter performance and component ratings.

（2）Study on DC filter performance and component ratings.

（3）Study on interference with communication and radio and component ratings.

8　Study on DC high speed switch.

9　DC control and protection system design.

（1）Hierarchy and redundant design.

（2）Control function configuration and parameter optimization.

（3）Requirements for modulation control functions and parameter optimization.

（4）Study on zoning，configuration，redundancy design，and DC protection setting.

These items may be added or deleted based on project-specific requirements.

4.0.2　Technical Specifications for Related Equipment or Subsystems

Technical specifications for related equipment or subsystems shall be completed based on the aforesaid studies and designs.

1　Thyristor valve

2　Converter transformer

3　Smoothing reactor

4　Switchgear

5　Measuring device

6　Surge arrester

7　AC filter

8　DC filter

9　Insulator

10　Bushing

11　Operator control system in converter station

12　Pole control/converter control system

13　AC/DC station control system

14　DC protection system

15　Transient fault recorder system

16　Protection information management slave station

17　Energy metering system terminal

18　DC line fault locator

19　Converter station master clock system