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An Under frequency Load Shedding Scheme for

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An Under frequency Load Shedding Scheme for

  1. 1. AN UNDER FREQUENCY LOAD SHEDDING SCHEME FOR HYBRID AND MULTI AREA POWER SYSTEMS PRESENTED BY AJAY PRAKASH SINGH PSE 152603 EEE NIT WARANGAL UNDER THE GUIDANCE OF SREE B. NAGU
  2. 2. INTRODUCTION  What is under frequency load shedding scheme (U.F.L.S)  Need of U.F.L.S scheme  Previously used scheme (Adapted U.F.L.S) & related issues  Problem Statement Of U.F.L.S scheme  Simulation with Hybrid Power System & its Analysis  Simulation with Multi Area Power System & its Analysis  Conclusion
  3. 3. NEED OF U.L.F.S SCHEME U.F.L.S WILL MAINTAIN FREQUENCY WITHIN PERMISIABLE LIMIT IN CASE OF INTER CONNECTED OR ISOLATED P.S IN CASE OF FAULT • IN CASE OF SOURCE AND LOAD CONNECTION & DISCONNECTION SYSTEM PAPAMETER VARIES • MOREOVER OUTPUT OF DG’S ALSO CHANGE DURING LOAD SHEDDING PROCESS . • EFFECT IN PERPORMANCE AND RELIABILITY DECREASES • ISSUES RESULTS IN
  4. 4. HOW TO CONTROL FREQUENCY • In case of worst possible contingency results in highest initial rate of decay in frequency. • Amount of load shed ensures that frequency further do not fall below. • So we need to determine, number and size of shedding, It is done by hit and trial method. • Its not a trivial task it has too be done very precisely and accurately otherwise results in undesirable damage black outs and serious cost . • For this few schemes are there- 1. ADAPTIVE U.F.L.S SCHEME 2. NOVEL U.F.L.S SCHEME
  5. 5. ADAPTIVE U.F.L.S & ITS ISSUES • Power deficit is calculated bases on frequency derivative (at the time of disturbance) • Its advantage is we don’t have determine worst possible contingency • Calculated amount of load is shed based of power deficit. • If power deficit is occur due to gen. outage and islanding of power system • P cal < P actual . …...… … ……………………………… • Amount of load shed do not have a linear relation with power deficit … • New frequency U.F.L.S technique is based on frequency second derivative • Calculation of second derivative is very tedious …… ………… • In hybrid P.S power is not constant we require a scheme independent of . Parameter . . . disadvantage
  6. 6. U.F.L.S SCHEME • U.F.L. S scheme uses fre. first derivative , only one parameter that effect power deficit is H • In first step estimated H is used, & in next step updated H will be used • power deficit is Cal by swing equation • Since this scheme is based on fre first derivative it will account for all the sudden change of power due to DG’s. Pd =2Heq f'Hz /t = t0 fN ADVANTAGE • Independent of system parameter……………………………………………………………………… • Consider changes in generated power during load shedding …………………………………………...
  7. 7. Cal power deficit (Pd) start SPECIFY THE LOAD TO BE SHED If Fo-Fk/fo *100 >=T.LS(k) UPDATE INERTIA & POWER DEFICIT FOR NEXT STEP If F > 0 If F < 48.4 Shed all the remaining loads shedding steps Stop no yes yes no
  8. 8. SIMULATION WITH HYBRID POWER SYSTEM & ITS ANALYSIS SCENARIO 1 : ISLANDING HYBRID POWER SYSTEM SCENARIO 2 : DECREASE IN SUN IRRADIANCE DURING L.S
  9. 9. SIMULATION WITH HYBRID POWER SYSTEM & ITS ANALYSIS SCENARIO 3: INERTIA CONSTANT VARIATION
  10. 10. SIMULATION WITH HYBRID POWER SYSTEM & ITS ANALYSIS SCENARIO 4 : IN CASE OF WIND TURBINE OUTAGE
  11. 11. SIMULATION WITH MULTI AREA POWER SYSTEM & ITS ANALYSIS BLOCK DIAGRAM OF MULTI AREA P.S IN CASE OF FAULT ALL FREQUENCY VARY AND FLUCTUATE BUT Fcoi IS SMOOTHLY VARRY
  12. 12. SIMULATION WITH MULTI AREA POWER SYSTEM & ITS ANALYSIS IN CASE OF POWER DEFICIT IN AREA 1 ,THERE IS STEP CHANGE IN Fcoi & FI BOTH CAN BE USED TO ESTIMATE POWER TO MAINTAIN POWER SYSTEM STABILITY DERIVATIVE OF Fcoi IS USED SINCE IN IS NOT VARRYING FAST .
  13. 13. SIMULATION WITH MULTI AREA POWER SYSTEM & ITS ANALYSIS IN CASE OF POWER DEFICIT FREQUNCY RESPONSE SHOWS THAT SCHEME IS SUCCESSFUL EFFECT OF CHANGE IN ‘H’ ON U.F.L.S SCHEME : ‘H’ IN INCRESE BY 50% • .
  14. 14. SIMULATION WITH MULTI AREA POWER SYSTEM & ITS ANALYSIS EFFECT OF CHANGE IN ‘H’ ON U.F.L.S SCHEME : ‘H’ IN INCRESE BY 50% EFFECT OF CHANGE IN SYSTM PARAMETER ( R,D,Tg,Tt)
  15. 15. CONCLUSION An U.F.L.S scheme for a hybrid distribution system including PV, FC, DEG, and BESS was proposed. Under frequency load shedding scheme is successful in determination of load shed and maintain the frequency within limit for various scenarios for hybrid and multi area power system.
  16. 16. REFRENCES  U. Rudez and R. Mihalic, “Monitoring the first frequency derivative to improve adaptive under frequency load-shedding schemes,” IEEE Trans. Power Syst., vol. 26, no. 2, pp. 839–846, May 2011.  A. Ketabi and M. H. Fini, “An under frequency load shedding scheme for islanded microgrids,” Int. J. Elect. Power Energy Syst., vol. 62, pp. 599–607, Nov. 2014.  J. J. Ford, H. Bevrani, and G. Ledwich, “Adaptive load shedding and regional protection,” Int. J. Elect. Power Energy Syst., vol. 31, no. 10, pp. 611–618, Nov./Dec. 2009.  U. Rudez and R. Mihalic, “A novel approach to under frequency load shedding,” Elect. Power Syst. Res., vol. 81, no. 2, pp. 636–643, Feb. 2011.

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