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CROSS CHANNEL OLD CONNECTION SCHEME

 

 

Between :     Lydd, England and Echinghen, France

 

 

Power Co :    Central Electricity Generating Board and Electricite de France

 

 

Manufacturer :

              ASEA, Sweden

 

 

Commissioned :

              8 December 1961 - decommissioned 1984

 

 

 

CROSS CHANNEL LINK SCHEME

BIPOLE 1 AND BIPOLE 2

 

 

 

Between:      SELLINDGE (Kent) - UNITED KINGDOM and BONNINGUES LES CALAIS - FRANCE (name of the substation : Les Mandarins).

 

Manufacturers:

              SELLINDGE

 

              Main plant and 400 kV substation : GEC Transmission and Distribution Projects Ltd., UK

 

              Converter Transformers, 400 kV filter disconnectors and DC disconnectors : NEI

 

              DC Reactors : Hawker Siddeley

 

              LES MANDARINS

 

              CGEE-ALSTHOM and ALSTHOM-ATLANTIQUE as main contractors (FRANCE).

 

Commissioned:      First stage :    500 MW March 1985

              First bipole :  1000 MW September 1986

              Second bipole : 1000 MW October 1986

 

Main Purpose: Energy trading between the CEGB and EDF systems by exploitation of the different daily load curves and generating plant mix (different percentages of a nuclear plant, very little hydro generation in the CEGB).

 

 

 

 

Main Data:    Two bipoles, 1000 MW each at ± 270 kV and 1852 A per pole. When one converter pole is unavailable, cable return is possible.

 

              Overload capacity : none.

 

A.C. Networks:          SELLINDGE

 

              The converter station is connected into the 400 kV double circuit line between Canterbury and Dungeness by means of a fifteen switch, double busbar, 400 kV SF 6 insulated substation. Two three-phase transformers per pole feed a twelve pulse bridge.

 

              One transformer is YNyO and the other is YNd11, both being rated at 315 MVA, 400 + 23 %-9% / 117 kV. A spare transformer of each type is available on site.

              The minimum short circuit capacity which would normally be expected is 4800 MVA.

 

 

              LES MANDARINS

 

              Three single phase transformers per pole with two secondary windings feed a twelve pulse bridge. The rating of the transformers are :

 

              206/103/103 MVA 400 ± 10 %/118/118/ 3 kV

 

              The winding of the 400 kV side is star connected whilst the windings on the valve side are either star connected or delta connected depending on their position. One spare transformer is held on site. The minimum short circuit capacity normally espected is 3800 MVA.

 

HVDC System:  Mean route length : 70 km.

 

              Land cables total length 25 km (18.5 km in England, 6.35 in France).

              Both French and English land cables, of which there are eight, are of the oil filled impregnated paper type. In France the cables of the two bipoles are installed in two different trenches. A single copper conductor type is used on Bipole 1 with a conventional stranded wire conductor with central oil channel for Bipole 2. The copper cross section in both cases is 900 mm2.

             

 

             

 

              In England the cables of each bipole are of different manufacture and are laid in separate routes, both being of 800 mm2 copper cross section.

             

              Submarine cables (length 46 km)

             

              The cables of the mass impregnated paper type (solid type) and are laid in pairs along four separate routes spaced about 1 km apart. The cables are embedded for their total length in a 1.5 m deep trench. The copper cross section for both English and French cables is 900 m2.

 

 

D.C. Filters: No special D.C. filters are used.

 

 

HVDC Valves: 

              Air cooled and insulated thyristor valves are used in both terminals.

 

              SELLINDGE

 

              Each pole comprises a twelve pulse converter of three quadruple valves (a vertical stack of four valves), in separate valve halls. Each valve is made up of 125 modules, with two thyristors in parallel, all connected in series.

 

              The rating is 270 kV at 1903 Amperes. There is one D.C. reactor of 350 mH per pole rated at ± 270 kV and 1903 Amperes.

 

              LES MANDARINS

 

              Each pole consists of a twelve pulse converter unit. The twelve valves of a pole are housed in three indoor valve structures. Each valve is composed of twelve modules in series connection. Each module has eight thyristors levels in series and each level has two thyristors in parallel connection in order to reduce the losses.

 

              The converter unit is rated for 270 kV abd 1852 A. One D.C. reactor is connected at the high voltage side of the converter. It is rated for 270 kV D.C. and 370 mH at 1852 A.

 

 

 

 

 

 

 

 

 

A.C. Filters:

              SELLINDGE

 

              The filters are connected at 400 kV and individually switched by SF6 insulated current breaker designed for outdoor use. The total installation is 1040 MVAr divided between  eight filters of 130 MVAr each. Each bipole set of four filters consists of two"C" type which are tunded to approximately the third harmonic, and two second order damped, tuned to approximately the eleventh harmonic.

 

 

C1

C2

CD

L

R

C

 2.6 µF

 24 µF

 

424   mH

666 ohms

2nd order

 

 

 

 35.4 mH

214 ohms

 

             

              LES MANDARINS

 

              Total installed : 1280 MVAr divided in eight filters of 160 MVAr each. All filters are of the high-pass damped type. One half is designed for harmonics 11. and 13. (2nd order filter) and the other for low-order harmonics (3rd order filter).

             

 

 

C1

C2

L

R

HP2

3.18 µF

none

27.8 mH

234 ohms

HP3

3.25 µF

9.55 µF

74.3 mH

 35 ohms

 

 

Static Compensators:

 

              Three high speed static compensators of the saturated reactor type are installed on the English side ; two at Sellindge and one at Ninfield Substation.

 

              Each compensator consists of a 157.3 MVAr saturated reactor connected at 56.6 kV via 400/56.6 kV, 150 MVA, 5.83 % reactance step down transformer, in series with a 451 F capacitor.


 

              In parallel with the saturated reactor are three types of filters : an 84 MVAr switched filter (detuned, 3rd harmonic), 14.7 MVAr unswitched filter (detuned 3rd harmonic) and a 15.6 MVAr unswitched filter "C" type filter (2nd harmonic).

 

 

 

 

 

References :

 

 

 

 

System Correspondent :

 

                   Mr A.R. FINNIS

              National Grid Company

              Sellindge Converter Station

              Church Lane, Sellindge

              Ashford

              Kent TN25 6AF

              ENGLAND

 

              Telephone : + 44 1303 815 215

              Telefax   : + 44 1303 815 219

              E-mail    : andy.finnis@ngc.co.uk    

             

              M. Philippe MAZINGARBE

              Electricite de France

              IFA2000

              CD 243 - 62340

              Bonningues Les Calais

              FRANCE

 

              Telephone : + 33 3 21 850927

              Telefax :   + 33 3 21 820554


TABLE 1

 

 Code

Redundancy

 Reserv System

 

 Spare parts

 

2000 MW CROSS CHANNEL

 

Yes/No

 Yes/No

Min. time needed

Yes/No

Min. time needed

SELLINDGE CONVERTER

 

 

 

 for change 

 

for install spares

STATION

 

1)

2)

over (hours)

3)

(hours)

 

 

 

 

 

 

 

  AC Filter and Shunt  Bank

 AC-E.F

    Yes

    No

-

    Yes

        2 hrs.

  AC Switchyard Equipment

 AC-E.SW

    No

    No

-

    Yes

       12 hrs.

  AC Control and Protection

 AC-E.CP

    Yes

    No

-

    Yes

        1 hr.

  Converter Transformer

 AC-E.TX

    No

    No

-

    Yes

     168 hrs.

  Synchronous Compensator

 AC-E.SC

    -

    -

-

    -

        -

  AC and Auxilliary Equipment

 AC-E.AX

    Yes

    Yes

0.5 hr.

    Yes

      48 hrs.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  Valve Electrical

 V.E

    Yes

    No

-

    Yes

        4 hrs.

  Valve Cooling (integral with valve)

 V.VC

    Yes

    No

-

    Yes

        8 hrs.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  Local HVDC Control and Protection

 C-P.L

    Yes

    Yes

0.5 hr.

    Yes

        0.5 hr.

  Master HVDC Control and Protection

 C-P.M

    Yes

    No

-

    Yes

        0.5 hr.

  Telecommunication

 C-P.T

    Yes

    No

-

    Yes

        4 hrs.

 

 

 

 

 

 

 

 

 

 

 

 

 

   

  DC Filters

 DC-E.F

    No

    No

-

    Yes

       12 hrs.

  DC Switching Equipment

 DC-E.SW

    No

    No

-

    Yes

       12 hrs.

  DC Ground Electrode

 DC-E.GE

    -

    -

-

    -

         -

  DC Ground Electrode line

 DC-E.EL

    -

    -

-

    -

         -

  Other DC Yard and Valve Hall Equipment

 DC-E.O

    No

    No

 

    Yes

       12 hrs.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  DC Transmission Line

 TL

    No

    No

-

    Yes

      120 hrs.

1) 2) 3) Please give more detailed information on table 2


 

*  CROSS CHANNEL  *

SELLINDGE

TABLE 2

 

1 * REDUNDANCY

 AC-E.AX Except valve cooling auxiliary power supply.

        
 C- P.L  Protection systems only, not Converter Control










 2 * RESERV SYSTEM

 AC-E.AX Cooling system processor
         Cooling system auxiliary power

 C-P.L   Converter Control only









 

 3 * SPARE PARTS

     The times used to install spares refer to the
     following example :
 AC-E.F  A filter capacitor unit
 AC-E.SW AC surge arrester
 AC-E.CP Any control or protection circuit board
 AC-E.TX Converter transformer LV bushing
 AC-E.AX 11 kV auxiliary transformer
 V-E     Thyristor module
 V-VC    Main cooling fan hub diaphragrm
 C-P.L   Circuit board
 C-P.M   Circuit board
 C-P.T   PLC line end filter control unit
 DC-E.F  No spare DC reactor kept but PLC equipment kept
 DC-E.SW Disconnector
 DC-E.O  Valve stack support insalutor
 TL      Submarine cable fault

 


TABLE 1

 

 Code

Redundancy

 Reserv System

 

 Spare parts

 

2000 MW CROSS CHANNEL

 

Yes/No

 Yes/No

Min. time needed

Yes/No

Min. time needed

MANDARINS CONVERTER

 

 

 

 for change 

 

for install spares

STATION

 

1)

2)

over (hours)

3)

(hours)

 

 

 

 

 

 

 

  AC Filter and Shunt  Bank

 AC-E.F

    No

    Yes

Less than 1 mn

    Yes

 See item 1

  AC Switchyard Equipment

 AC-E.SW

    No

    No

 

    Yes

 

  AC Control and Protection

 AC-E.CP

    Yes

    No

 

    Yes

 1 h for one card

  Converter Transformer

 AC-E.TX

    No

    Yes

72 h one TR-phase

    Yes

 

  Synchronous Compensator

 AC-E.SC

 

 

 

 

 

  AC and Auxilliary Equipment

 AC-E.AX

    Yes

    No

 

    Yes

 1 h

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  Valve Electrical

 V.E

    Yes

    No

 

    Yes

1 h for one module

  Valve Cooling (integral with valve)

 V.VC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  Local HVDC Control and Protection

 C-P.L

    Yes

    No

 

    Yes

1 h for one card

  Master HVDC Control and Protection

 C-P.M

 

 

 

 

 

  Telecommunication

 C-P.T

    Yes

    No

 

    Yes

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  DC Filters

 DC-E.F

 

 

 

 

 

  DC Switching Equipment

 DC-E.SW

    No

    No

 

    Yes

4h for DC commut.

  DC Ground Electrode

 DC-E.GE

    No

    No

 

    No

             switch

  DC Ground Electrode line

 DC-E.EL

    No

    No

 

    No

 

  Other DC Yard and Valve Hall Equipment

 DC-E.O

    No

    No

 

    Yes

 see item 2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  DC Transmission Line

 TL

    No

    No

 

    Yes

 see item 3

1) 2) 3) Please give more detailed information on table 2


*  CROSS CHANNEL  *

MANDARINS

TABLE2

 


        










     ITEM 1 : 1 h  for replace capacitor
              4 h  for replace reactor
              1 h  for replace resistor




     ITEM 2   ?    for DC-side surge arrester
              No   No spare smoothing reactor
              2 h  for measuring transducer
              4 h  for buswork insulator
              8 h  for wall bushing




 

     ITEM 3   480 h    for repear after a fault on
                        DC land cable
              840 h    for repear cable after a fault
                        on submarine embeding cable