GB/T 50789-2012 in English

1 General

1.0.1 This code is developed to regulate the design of±800kV DC converter stations so as to ensure they comply with applicable national policies and regulations and meet the requirements on safety, reliability, advancement, appliability, economy, and environmental friendliness.

1.0.2 This code applies to the design of converter stations of±800kV two-terminal DC transmission system.

1.0.3 The converter stations shall be designed based on the project specific characteristics, using the available new technologies, equipment, materials and workmanship.

1.0.4 When designing converter stations, effective measures shall be taken to reduce land occupation, protect environment and ensure work safety.The environmental protection, soil and water conservation, and work safety and hygiene facilities shall be designed in parallel with the main works.

1.0.5 In addition to this code, the design of±800kV converter stations shall also comply with the relevant national standards in force.

2 Terms

2.0.1
converter
the equipment in converter stations used for AC-DC or DC-AC conversion, also known as converter valve group.Converter valves are generaly connected in a circuit to convert current.A converter may be comprised of one or more three-phase bridge converter circuit (s) (also known as sixpulse converter or converter valve group)connected in series or parallel.Two series-connected six-pulse converters with a 30° phase displacement can form one 12-pulse converter, also called 12-pulse converter group.By varying the triggering phase position of converter valves, a converter can be operated in both rectification and inversion mode.Specifically, a converter which converts alternating current to direct current is called rectifier while a converter which converts direct current to alternating current is called inverter.Rectifiers and inverters are basically the same and are collectively called converters.Unless otherwise specified, "valve group"mentioned in this code refers to 12-pulse converter valve group only.

2.0.2
converter valve
The bridge arm serving as the basic unit of three-phase bridge converters for current conversion in DC transmission systems, also called single valve unit.In modern DC transmission, semi-conductor converter valve is a generic name for the bridge arm main circuit consisting of series-or parallel connected semi-conductor power electronics and their associated auxiliaries contained in the same housing.

2.0.3
double valve unit
for a 12-pulse valve group wiring, it has two 6-pulse valve groups connected in series, one 6-pulse valve group has each of its phase composed of two converter arms, and two converter arms of each phase are structurally closely connected forming a valve tower, known as a double valve unit.

2.0.4
quadruple valve unit
for a 12-pulse valve group wiring, it has two six-pulse valve groups connected in series, one sixpulse valve group has each of its phases composed of two converter arms, and four converter arms of each phase are structurally closely connected forming a valve tower, known as a quadruple valve unit.

2.0.5
thyristor valve
semi-conductor valves consisting of thyristor elements and their auxiliaries.

2.0.6
valve hall
buildings used to house converter valves.They are the main buildings in converter stations.The valve hall is generally arranged on 12-pulse converter unit basis, i.e., converter bridges and relevant equipment of one converter unit are arranged in a separate valve hall.

2.0.7
high voltage vall hall
The building which houses the converter bridges and associated equipment of the converter unit close to the line pole in cases where each pole consists of two series-connected 12-pulse converter units.

2.0.8
low voltage vall hall
the building which houses the converter bridges and associated equipment of the converter unit close to the neutral bus in cases where each pole consists of two series-connected 12-pulse converter units.

2.0.9
auxiliary equipment of converter station
other facilities required to ensure normal operation of the main equipment of a converter station, mainly including auxiliary power system, converter valve cooling system, valve hall air conditioning system, fire fighting facilities and station earth.

2.0.10
by-pass breaker circuit
an electrical circuit which serves to switch on/off the 12-pulse converter valve group connected to it in cases where each pole consists of multiple valve groups connected in series.It is generally comprised of one by-pass circuit breaker, disconnectors for maintenance purpose on both sides of the breaker, and one by-pass disonnector in parallel with the breaker.

2.0.11
operational control mode
control modes adopted for converter units, poles or converter stations to maintain operational parameters of converter station at the expected values.

2.0.12
additional control mode
control modes adopted for converter units, poles or converter stations to help maintain operational parameters of AC systems connected to converter stations at the expected values.

2.0.13
master station/slave station
In a two-terminal DC transmission system, one converter station is defined as the master station and the opposite one the slave station.The control system of the master station, which is usually the rectifier station, receives control orders issued by the dispatch center or station operating personnel and send these orders to the slave station via the telecontrol system.The master station and slave station can be switched over between each other if the telecontrol system is in order.

2.0.14
telecontrol system
the system used for transmitting and processing the DC system control signals, protection signals, operation signals and monitoring signals required to be exchanged between two ends.

2.0.15
pole control
the equipment which serves to control and monitor one pole at the converter station and generally consists of the host computer, I/O modules, field bus, etc.

2.0.16
converter valve unit control
control and monitoring equipment provided between the pole control and valve base electronics on valve group basis.

3 Siting of Converter Stations

3.0.1 The converter stations shall be sited in accordance with the siting requirements given in DL/T5218 Technical Code for Designing220kV-500kVSubstation and through techno-economic comparsion and economic benefit analysis while considering the power system planning, urban and rural planning, contamination conditions, water sources, transportation, land resource, environmental protection, and location of earth electrode as well as the process characteristics of±800kV converter stations.

3.0.2 The siting of converter stations shall take into consideration their importance and roles in the power system.The rectifier station should be located near the power source while the inverter station near the load center.When more than one converter stations are to be built in one region, they shall be sited considering the effects of various factors on the power system, including the electrical distance between individual converter stations, common earth electrode, damages caused by external forces, etc.

3.0.3 The station sites shall be kept away from any serious pollution sources.When it is difficult to do so, the converter stations shall be sited on the upwind side of the prevailing wind direction to the serious pollution sources and their effects shall be evaluated.

3.0.4 The siting shall comply with relevant requirements of GB50011 Code for Seismic Design of Buildings and GB50011 Code for Investigation of Geotechnical Engineering.