Lisbeth Söderling, Power Systems, HVDC Technology Seminar, Addis Ababa, November 2013 HVDC Classic Control and protection. ABB Month DD, YYYY Slide 1

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1 Lisbeth Söderling, Power Systems, HVDC Technology Seminar, Addis Ababa, November 2013 HVDC Classic Control and protection Month DD, YYYY Slide 1

2 HVDC Classic Control and Protection System Functionality Nov 30, 2013 Slide 2

3 HVDC Classic Control and Protection System General structure Standard database server for long term storage Fast Ethernet LAN (100 Mbit/s) PCP A PCP B VC Operator workstations with Windows NT Remote operator workstations Bridge/Firewall Operation & Maintenance Control & Protection computers Valve Control Electro optical interface Thyristor Monitoring Main Computers optical I/O extension Process and Process Interfaces Nov 30, 2013 Slide 3

4 HVDC Classic control General principle To other station Uac + Ud - P order Power control I order Direct current- & Firing Control system P mod I d Id response Ud response Voltage measuring system Nov 30, 2013 Slide 4

5 HVDC Classic control Cooperation between converter stations Converter 1 Converter 2 U ac1 U ac2 U d1 U d2 I o1 Iresp. CCA CFC CPG CPG CFC I d1 I d1 CCA Iresp. I o2 Nov 30, 2013 Slide 5

6 Static Ud/Id characteristics Rectifier current control U d Normal operating point Current control (conv 2) Current control (conv 1) I d I 0rd conv2 I 0rd conv 1 Nov 30, 2013 Slide 6

7 HVDC Classic control Relationships between converter stations U d Normal operating point Current control (conv 2) Current control (conv 1) I 0rd conv2 I 0rd conv 1 I d The station with the highest current order (Iord) is operating as a rectifier The station with the highest available DC voltage (Ud) will normally control the direct current (Id) The station with the lowest available DC voltage will normally determine the DC voltage Nov 30, 2013 Slide 7

8 HVDC Classic control DC Power Control, purpose and basic features Variations in DC voltage are compensated by adjusting the DC current to keep the power level constant The power order is set from dispatch or locally [MW] The ramp rate is set [MW/min] + Uac Ud - P order P mod I Power control order Direct current- & Firing Control system I d Ud response I response Voltage measuring system Nov 30, 2013 Slide 8

9 HVDC Classic control Principle of power modulation P o D P ord D f K D P mod Dead band setting Gain setting Nov 30, 2013 Slide 9

10 HVDC Classic control Current Control Amplifier (CCA) HVDC control system To other station Uac + Ud - P order P mod Power control I order Current control amplifie r Firing Control & CPG I d I response U d response Voltage measuring system Adjusts the current order Io with the current response ID The output is the reference value of the firing angle, ALPHA order, which is sent to the firing control Nov 30, 2013 Slide 10

11 HVDC Classic control Converter Firing Control (CFC) The CFC shall assure that firing of a valve is accurately synchronized with the AC-voltage Avoid Firing a valve outside certain time limitations HVDC control system To other station Uac + Ud - P order P mod Power control I order Current control amplifie r Firing Control & CPG I d I response U d response Voltage measuring system Nov 30, 2013 Slide 11

12 HVDC Classic control Control Pulse Generator (CPG) In the Control Pulse Generator (CPG) the calculated time to fire a valve (CP calc) is turned into 6 (or 12) individual Control Pulses which are distributed to the corresponding thyristor valves. HVDC control system To other station Uac + Ud - P order P mod Power control I order Current control amplifie r Firing Control & CPG I d I response U d response Voltage measuring system Month DD, YYYY Slide 12

13 HVDC Protections Purpose of the protections system To avoid Equipment Damages To avoid Collapse of the Electrical System Nov 30, 2013 Slide 13

14 HVDC Protections Basic Philosophy Detection of faults or abnormal conditions Take the exposed equipment out of service Faults and abnormal conditions should be detected by at least two protections When possible, different protection are used and arranged into overlapping zones If possible, a control action should relieve stress before the protection operates Testing and maintenance should be possible with the Pole in operation. Redundant Trip Paths are used (separate paths for A- & B- system respectively) Nov 30, 2013 Slide 14

15 HVDC Protections Structure Converter protections Pole protections Bipole protections AC-filter & AC-bus prot. Supervisory protections Nov 30, 2013 Slide 15

16 HVDC Protections Basic fault clearing actions The following basic switching actions are used to clear faults in the HVDC station: PCP A PCP B Valve Control Transfer to redundant control systems (some protections). Retarding the firing delay angle α and blocking of firing pulses. Tripping of Bridge transformer breakers. Tripping of AC-filter bank breaker. Start breaker failure* protection. *) A failure of an AC-breaker to extinguish a fault current or to open its contacts when ordered) Nov 30, 2013 Slide 16

17 HVDC Protections Blocking of the Bridge The bridge protection sequence should handle all types of protection actions from both bridge protections and pole protections. The protections are divided in three basic categories: X ; always blocking without by-pass pair Generally used during valve faults Y ; conditional blocking Generally used for DC side faults which do not expose the equipment to serious stresses, AC faults and manual blocking of the pole Z ; always blocking with by-pass pair Generally used when ground faults or overcurrents are detected on the DC side Nov 30, 2013 Slide 17

18 HVDC Protections Converter level protections Valve Short Circuit Protection Commutation Failure Protection Voltage Stress Protection Valve Misfire Protection Thyristor Monitoring High Angle Supervision DC Overcurrent Protection Low AC Voltage Detection Last Line Disconnect Protection Nov 30, 2013 Slide 18

19 HVDC Protections Converter level protections IP DCP430 THYRISTOR MONITORING AVP130 LOW VOLTAGE DETECTION DCP210 VOLTAGE STRESS PROTECTION OLTC LAST LINE DISCONNECT PROTECTION DCP220 HIGH ANGLE SUPERVISION ALPHA GAMMA Udi0 CWT DCP310 VALVE SHORT CIRCUIT PROTECTION DCP130 COMMUTATION FAILURE PROTECTION DCP110 DC OVERCURRENT PROTECTION DCP410 VALVE MISFIRE PROTECTION Nov 30, 2013 Slide 19 1JNL Convprot.hgf CWT CP FP

20 HVDC Protections Commutation Failure Definition and protective action IDL NORMAL DC CURRENT PATH 1 * 3 5 CURRENT PATH AT A COMMUTATION FAILURE UDL 4 6 ** 2 IVY IVD IDNE UDN * THE COMMUTATION FROM VALVE 1 TO 3 FAILS ** AT THE NEXT FIRING OF VALVE 4 THE COOMUTATION FAILURE IS FULLY DEVELOPED Order protective blocking: (All blocking action preceeded by control system changeover) X-block, 6-pulse bridge, control pulse transmission fault Y-block, 12-pulse bridge, AC network disturbance Nov 30, 2013 Slide 20

21 HVDC Protection Valve Short Circuit Protection SHORT CIRCUIT CURRENT PATH DC CURRENT PATH IDL IVY UDL IVD Order block (X) before the third valve is fired UDN IDNE Nov 30, 2013 Slide 21

22 HVDC Protections Pole Protections ALPHA IVY IVD DLP140 DC UNDERVOLTAGE PROTECTION DLP130 DC OVERVOLTAGE PROTECTION DLP110 DC CABLE GROUND FAULT PROTECTION OPEN LINE TEST PROTECTION DPP110 POLE DC DIFFERENTIAL PROTECTION NBS DLP330 ELECTRODE LINE OPEN CIRCUIT PROTECTION DPP120 DC HARMONIC PROTECTION BFP413 NEUTRAL BUS SWITCH FAILURE PROTECTION 1JNL Poleprot_Fiume.hgf Nov 30, 2013 Slide 22

23 HVDC Protections DC Line Ground Fault IDL IVY UDL IVD CURRENT PATH FOR NEUTRAL SIDE EARTH FAULTS CURRENT PATH FOR HIGH SIDE EARTH FAULTS CURRENT PATH FOR SINGLE PHASE EARTH FAULTS UDN IDNE Nov 30, 2013 Slide 23

24 HVDC Protections DC Line Ground Fault Protection Detects ground faults by measuring the level of the line/cable voltage and the derivatives of the DC voltage and current Measures UDL and IDL Action: The protection initiates control actions to extinguish the fault current on purpose, to restore the power transmission after the fault has been cleared If the restart attempts fail; Y-block, pole isolate The protection is active in the rectifier terminal only Nov 30, 2013 Slide 24

25 AC Filter Protections HP 24/36 HP 12 AC Filter Capacitor Unbalance and Earth Fault protections AC Filter Harmonic Overload protections AC Filter Detuning Supervision Breaker Failure protection AFP420 AC FILTER REACTOR/RESISTOR OVERLOAD PROTECTION AFP520 AC FILTER ZERO SEQUENCE CURRENT PROTECTION AFP450 AC FILTER DETUNING SUPERVISION AFP420 AC FILTER REACTOR/RESISTOR OVERLOAD PROTECTION AFP520 AC FILTER ZERO SEQUENCE CURRENT PROTECTION AFP450 AC FILTER DETUNING SUPERVISION CAP30 AC FILTER CAPACITOR UNBALANCE PROTECTION BFP20 AC FILTER BREAKER FAILURE PROTECTION 1JNL Filterprot1.hgf Nov 30, 2013 Slide 25

26 HVDC Protections Supervisory Protections Valve misfire supervision Thyristor monitoring Excessive delay angle supervision Low AC Voltage Detection Minimum Filter Protection Nov 30, 2013 Slide 26

27 Software Design Nov 30, 2013 Slide 27

28 HVDC Control & Protection, HiDraw programming and documentation tool HiDraw automatically generates code from Function Block Diagrams. Eliminates the time-consuming and tedious manual coding from the software design process. HiDraw supports reuse of software and hierarchical design. The cut in the V-model can be moved upwards. Requirement Specification Factory System Testing Design Specification HiDraw Integrated Testing Detailed Design Module Testing Coding Month DD, YYYY Slide 28

29 HVDC Control & Protection, MACH Software Design, Graphical CodeGenerator Nov 30, 2013 Slide 29

30 HVDC Control & Protection, MACH Software Design HiBug - illustration Real Time values are shown in red Nov 30, 2013 Slide 30

31 XEX Level Schedule Level 1: 1 tic Level 2: 2 tic Level 3: 6 tic Level 4: 12 tic Level 5: 24 tic Level 6: 48 tic Rev Ind Rev ision Appd Year Week TASK/PROC ACTIVE Entry TASK NoEntry TASK/PROC ACTIVE Entry TASK NoEntry TASK/PROC ACTIVE Entry TASK NoEntry TASK/PROC ACTIVE Entry TASK NoEntry TASK/PROC ACTIVE Entry TASK NoEntry TASK/PROC ACTIVE Entry TASK NoEntry TASK/PROC ACTIVE Entry TASK NoEntry TASK/PROC ACTIVE Entry TASK NoEntry TASK/PROC ACTIVE Entry TASK NoEntry TASK/PROC TASK/PROC Des ign c hec k ed by Name: Func %p7 FUNCTIONAL DIAGRAM Drawing c hec k ed by Space f or explanation %p6 OWN FUNCTION Proc.ty pe: %p9 Drawn by Is s by Dept Year W eek Ty pe: TASK %p5 ABB POWER TECHNOLOGIES %p8 %p4 ACTIVE Entry TASK NoEntry TASK/PROC ACTIVE Entry TASK NoEntry ACTIVE Entry TASK NoEntry %p3 %p1 %p2 Rev Ind Sheet Rev Ind Sheet Cont 1002 HVDC Control & Protection, MACH Software Design Two ways of using the same HiDraw application HiDraw Application in the form of Function Block Diagrams Used in the control and protection equipment Used for Dynamic Performance Studies (real time execution) (Equipped with a special slowed down real time scheduler) Nov 30, 2013 Slide 31

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