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SPECIAL PROTECTION SCHEMES PowerPoint Presentation
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SPECIAL PROTECTION SCHEMES

SPECIAL PROTECTION SCHEMES

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SPECIAL PROTECTION SCHEMES

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  1. SPECIAL PROTECTION SCHEMES S.P.KUMAR CM(SRC&S) SRLDC, BANGALORE

  2. SPECIAL PROTECTION SCHEMESDEFINITION PROTECTION SCHEME DESIGNED TO DETECT ABNORMAL SYSTEM CONDITIONS AND TAKE PREDETERMINED CORRECTIVE ACTION (Other than isolation of faulty element) TO PRESERVE SYSTEM INTEGRITY AND PROVIDE ACCEPTABLE SYSTEM PERFORMANCE

  3. WHAT IS SPS? According to P.M.Anderson SPS is defined as “ a protection scheme that is designed to detect a particular system condition that is known to cause unusual stress to the power system and to take some type of predetermined action to counteract the observed condition in a controlled manner. In some cases, SPSs are designed to detect a system condition that is known to cause instability, overload, or voltage collapse. The action prescribed may require the opening of one or more lines, tripping of generators, ramping of HVDC power transfers, intentional shedding of load, or other measures that will alleviate the problem of concern.”

  4. SECURITY WEAKENED. INCLEMENT WEATHER. ALL CONSTRAINTS ARE MET. SECURITY MONITORING TOOLS KICK IN. RRPA IS SUGGESTED TO BRING SYSTEM BACK TO NORMAL..LIKE GENERATION SHIFTING ETC RELIABILITY CRITERIA NOT MET. VOLTAGE AT BUSES MAY BE UNACCEPTABLY LOW. ELEMENT LOADING MAY EXCEED LIMITS. EMERGENCY CONTROL ACTIONS- FAULT CLEARING, EXCITATION CONTROL, LOAD SHED, GENERATION RUNBACK, HVDC MODULATION CASCADING OUTAGES, ISLANDING, MAJOR PARTS OF GRID ARE BLACKED OUT

  5. STABILITY • ‘Power system stability is the ability of an electric power system, for a given initial operating condition, to regain a state of operating equilibrium after being subjected to a physical disturbance, with most system variables bounded so that practically the entire system remains intact.’ Source:-P.M.Andersen

  6. FAST ACTING: WAMS BASED SPS GENERATION OR LOAD SHEDDING COMBINATION OF CONVENTIONAL RELAYS AND BROADBAND COMMUNICATION UFR, DF/DT DV/DT ,under VoltageRELAYS STABILITY IN POWER SYSTEMS Source:-VLPGO WG

  7. WHY SPS? OPERATIONAL REASONS • OUTAGE OF HIGH CAPACITY GENERATING UNITS,HVDC INTERCONNECTION OF LARGE CAPACITY • WIDE SEASONAL FLUCTUATION IN LOADING PATTERN • STAGGERING AND ROSTERING OF LOADS CAUSING UNPRECEDENTED SKEWING • SUDDEN IMPACT ON LARGE GRIDS DUE TO SYsTEM DYANAMICS AND SWINGS.

  8. WHY SPS? COMMERCIAL REASONS • SKEWED GENERATION AND LOAD PATTERN AND PRESSURE ON RELIABILITY MARGINS DUE TO • COMMERCIAL MECHANISMS • OPEN ACCESS INCREASE IN TRADE VOLUME • INCREASE IN COMPETITION • UNBUNDLING AND RESTRUCTURING

  9. WHY SPS? PLANNING ISSUES • ECONOMY OF SCALE, LARGE PITHEAD PLANTS AND LONG TRANSMISSION LINES • THE SYSTEM PLANNERS TEND TO UTILIZE THE EXISTING NETWORK • DELAYS IN NETWORK EXPANSION DUE TO ENVIRONMENTAL PROBLEMS • SEASONAL OVER LOADS • LINES AND GENERATORS NOT COMING IN TANDEM • EVACUATION OF RENEWABLES BY DEROGATING RELIABILITY CRITERIA

  10. AN EXAMPLE OF A BASIC SPS INCREASED TRANSFER CAPABILITY DEFFERED INVESTMENT INFINITE GRID B THIS NETWORK IS UNABLE TO EVACUATE MORE THAN 500 MW 2000 MW GENERATOR A SPS ACTION WOULD BE TO TRIP THE GENERATORS IN STAGES TO LIMIT FLOW ON A-B SECTION. IF SPS WERE NOT THERE THE GENERATOR WOULD BE CONSTRAINED OR A-B SECTION WOULD NECESSARILY HAVE TO BE STRENGTHENED CONVERTER TYPICAL FLOW OF 1800-2000 MW HIGH CAPACITY DC LINK INVERTER LOADS

  11. TRADITIONAL SCHEMES PROTECTS INDIVIDUAL ELEMENTS STANDARDISED MANUFACTURER DRIVEN NARROW ‘VISION’ LIMITED TO THE FAULTY ELEMENT MAY DEGRADE SYSTEM CONDITIONS FURTHER SPS DESIGNED TO DETECT SYSTEM DEFICIENCIES AND TAKE CORRECTIVE ACTION EVOLVED BY EXPERIENCE UNIQUE HOLISTIC APPROACH PRE-EMPTIVE IN NATURE PREVENTS SYSTEM DETERIORATION TRADITIONAL PROTECTION SCHEMES AND SPS

  12. SPS is used • During rare contingencies • When focus for the protection is on the power system supply capability rather than on a specific equipment • When consequences of an operating condition is outside the capability of conventional protection

  13. SPS Characteristics • Are normally sleeping systems • Operate infrequently • Control actions taken is predetermined • Can be armed or disarmed depending upon system conditions • Can comprise a large number of coordinated actions, in a cascaded manner • Under frequency controlled load shedding in a number of steps at different frequency levels and/or with different time delays

  14. SPS DESIGN • DEFINE THE CRITICAL CONDITION • STUDY OF PAST DISTURBANCES • LOAD FLOW AND STABILITY STUDIES • IDENTIFY RECOGNITION TRIGGERS • TRIP RELAYS, • HVDC POLE BLOCK SIGNALS • LOW VOLTAGE • LOW FREQUENCY • DF/DT • COMBINATION • SUPER TRIGGERS • OPERATOR CONTROL OF SPS • AUTOMATIC ARMING/DISARMING • MANUAL BASED ON OPERATORS NOMOGRAMS/INFORMATION

  15. OPERATOR NOMOGRAM FOR ARMING/DISARMING SPS ARM SPS-450 1000 MW ARM SPS-1000 FLOW ON RAIPUR-ROURKELA CRITICAL SITUATION IN OTHER PART OF GRID 100 MW 800 MW ΣFLOW ON BOTH CIRCUITS OF TALCHER-ROURKELA

  16. Advantages of SPS • Helps in operating power systems closer to their limits • Increase power transfer limit while maintaining the same level of system security • Increase the power system security particularly towards extreme contingencies leading to system collapse

  17. TYPICAL SPS ACTIONS • Generation rejection • Turbine fast valving/generator run-back • Gas turbine/Pumping storage start-up • Under frequency load shedding • Under voltage load shedding • Remote load shedding • HVDC fast power change • Automatic shunt reactor/capacitor switching

  18. TYPICAL SPS ACTIONS • Controlled disconnection of interconnection/ area islanding • Tap changer blocking and set point adjustment • Quick increase of generator voltage set point • Dynamic braking or braking resistor • Actions on the AGC such as set point changes

  19. PERCENTAGE OF MOST COMMON SPS

  20. INDUSTRY EXPERIENCE WITH SPS • REPORTED SCHEMES 111 • FIRST SPS INSTALLED IN 1930 • SCHEMES REPORTED BY GEOGRAPHICAL REGIONS SURVEY IS ONLY INDICATIVE Source:-P.M.Andersen

  21. EXPERIENCE WITH SPS IN BRAZIL SYSTEM Source:-Vlpgo wg

  22. SPS SCHEMES IN SR

  23. THE FIRST SCHEME: 1996CONDITIONS

  24. THE FIRST SCHEME: 1996CONDITIONS

  25. THE SR GRID IN 1996 BHADRAVATI 178x2 JEYPORE 267x2 187 2x221 RSTPP 155 1 P 301x2 189 279 GAZUWAKA P P KHAMMAM P HYDERABAD 317 277 P 221x2 P 115 258 VIJAYAWADA Nagjhari RAICHUR NAGARJUNASAGAR 172 120 302 146x2 MUNIRABAD 308 Kodasally P By Tripping of Salem-Bangalore and Cudddapah-Madras Southern Grid was getting devided into two blocks 52x2 P N KAIGA SIRSI GOOTY NELLORE P CUDDAPAH Kadra 173 DAVANAGERE 242 60 HIRIYUR 300 NELAMANGALA 182 P BANGALORE P 181 MAPS 330 28 MADRAS HOODY 151 63 175 164x2 P 54 SALEM 179 NEYVELI P UDUMALPET 130x2 P TRICHY P 130x2 127 TRICHUR P MADURAI FIG-2 THE FIRST SCHEME: 1996

  26. SPS’s proposed in SR and its status of implementation

  27. ORISSA TALCHER BHADRAVATI JEYPORE CHATTISGARH MAHARASHTRA RSTPP DITCHIPALLY KALPAKKA WARANGAL GAJWEL SIMHADRI GAZUWAKA AP KHAMMAM MMDP GHANAPUR P MAHABOOB NAGAR N’SAGAR VIJAYAWADA KAR RAICHUR KURNOOL MUNIRABAD NARENDRA SSLMM BTPS GOOTY KAIGA P GUTTUR KADAPA P NELLORE HIRIYUR TALGUPPA NELAMANGALA HOODY ALMATHY CHITTOOR SRIPERUMBUDUR KOLAR SOMANAHALLI KALAVINDAPATTU HOSUR TN MYSORE Highly loaded Medium loaded Lightly loaded NEYVELI SALEM NEYVELI TPS – 1 (EXP) PUGALUR UDUMALPET P TRICHY TRICHUR P MADURAI KER TIRUNELVELI TRIVANDRUM 400KV GRID MAP OF SOUTHERN REGION Typical flow directions in SR

  28. HVDC Kolar SPS

  29. Kolar SPS Logic: Trip signal-1

  30. Kolar SPS Logic: Trip signal-1: Load relief by constituents

  31. Kolar SPS Logic: Trip signal-2

  32. Kolar SPS Logic: Trip signal-2: Load relief by constituents

  33. KOLAR SPECIAL PROTECTION SCHEME

  34. Performance of the Scheme

  35. SPS AT TALCHER END

  36. SPS 450-1000

  37. Talcher SPS Logic: SPS 450:

  38. Talcher SPS Logic: SPS 1000:

  39. Talcher SPS Logic: SPS 1000:

  40. PROPOSED MODIFICATION TO SPS AT HVDC KOLAR

  41. PROPOSED MODIFICATION TO SPS AT HVDC KOLAR • LOGIC FAILS IF POWER GOES DOWN IN STEPS. SIGNAL 2 IS NOT SENT • GRID HOWEVER SEES A LARGER LOSS OF POWER • PROPOSED MODIFICATION: INCREASED WINDOW OF JUDGEMENT, LINE FAULT AS INPUT

  42. Talcher-Kolar SPS Logic Diagram MODIFIED

  43. PERFORMANCE OF THE SPS • Mal-operation On six occasions the scheme operated when not required to operate due to failure of the HVDC measuring equipments like Optodyne • Non operation. On Nine occasions defense mechanism failed to operate when required due to following reasons • On four occasions when one of the pole tripped on ground fault inter trip signal was not generated. The logic was working only on power flow levels and line fault signal was not used. This has been taken care in the Stage –II SPS logic development • Problem with the logic in 1 case, during the initial stages of the logic development, which was latter corrected. • In the remaining four cases, three cases non operation was due to the signal input. The power level signals were derived from HVDC control which was changing only in steps therefore decisions were influenced by the power levels in specified steps at times,could not detect the actual loss of power of more than 400MW. This has been taken care in the Stage –II SPS logic development • Remaining one case due to control supply failure Based on survey in 2003

  44. ANALOG INPUT DIGITAL INPUT PROGRAMMABLE LOGIC CONTROLLER ONLY ONE REQUIRED FOR AN SPS SCHEME DIGITAL OUTPUT DIGITAL TELEPROTECTION COUPLER K1 K1 K2 K2 K3 K3 K4 K4 FIBER OPTIC CABLE ≈ ONE SET FOR EACH SIGNAL PATH DIGITAL TELEPROTECTION COUPLER WIRED TO TRIP RELAY SPS PLC SCHEMATIC VIRTUAL MAPPING OF CONTACTS

  45. SPS FOR KOODANKULAM • CONTINGENCY LEVEL ABOUT THE SAME AS TALCHER-KOLAR • SINGLE UNIT TRIPPING : 1000 MW • STATION LOSS : 2000 MW • LARGE DIPS IN FREQUENCY LIKELY • CONVENTIONAL PROTECTION SCHEMES MIGHT BE INADEQUATE • LARGE INCREASE IN NORTH-SOUTH FLOWS LIKELY DUE TO TRIPPING • OSCILLATIONS IN THE SYSTEM • REDUCED SECURITY • TRUNK CORRIDOR LOADING