Utilization of Synchrophasors during Synchronization and Operation of Large Grids - Experience of Indian Grid Operator
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The document discusses the utilization of synchrophasors in the synchronization and operation of India's large electrical grids, highlighting various case studies and the grid's profile. It outlines the evolution of India's grid infrastructure, detailing the implementation of a wide area measurement system and the role of synchrophasors in enhancing real-time operations and fault detection. Additionally, it emphasizes the importance of regular monitoring and improvements in grid stability and situational awareness.
Utilization of Synchrophasors during Synchronization and Operation of Large Grids - Experience of Indian Grid Operator
- 1. Utilization of Synchrophasors during Synchronization and Operation of Large Grids - Experience of Indian Grid Operator Vivek Pandey Chandan Kumar Srinivas Chitturi 14-15 October NASPI Work Group Meeting, Chicago,IL
- 2. POSOCO, India 2ONE NATION-ONE GRID-ONE FREQUENCY Outline • Indian Grid Profile (2) • Wide Area Measurement System in India (2) • Case Study on Large Grids Synchronization and Operation • Case Study 1 : Synchronization of Large Grids (6) • Case Study 2 : Controlled Separation of Large Grids(1) • Case Study 3 : Detection of Islanding and its Resynchronization (2) • Case Study 4: Healthiness of Auto-Synchronization (2) • Conclusion (1)
- 3. POSOCO, India 3ONE NATION-ONE GRID-ONE FREQUENCY Indian Grid : Profile • Demarcated into Five Regional Grids • Installed Capacity : 276.7 GW (as on 31st July 2015) • Peak Demand : 147 GW (as on 31st Sept 2015) • Average Energy Consumption : 3.3 TWhr/Day • Large Generating Complexes of 4000 MW • Renewable Generation : 36 GW • Wind : 23.7 GW, Solar : 4 GW (On increasing trend) • Meshed Network of 765 kV and 400 kV Lines • Rapid growth in Generation, Transmission and Distribution Capacity. Northern Grid Western Grid Southern Grid Eastern Grid North Eastern Grid Population : 1.21 Billion as per Census 2011
- 4. POSOCO, India 4ONE NATION-ONE GRID-ONE FREQUENCY Indian Grid : Development • Federal Structure of Governance. • State Grids interconnected gradually to from 5 self-sufficient regional grids. • Northern, North Eastern, Eastern, Western and Southern Grid. • Asynchronous interconnection among regional grids. • Synchronous interconnection of regional grids Pre 1991: Five Regional Grids - Five Frequencies Merchant Power October 1991: East and Northeast synchronized Electricity Act, 2003, Open Access March 2003: Western Grid synchronized with East & Northeast Merging of Markets, Power Exchanges August 2006: North synchronized with Central Grid forming NEW Grid Addition of large 500 MW & above gen. units and 765 kV transmission Lines, Ultra Mega Power Projects Dec 2013: All India Synchronized Grid
- 5. POSOCO, India 5ONE NATION-ONE GRID-ONE FREQUENCY Wide Area Measurement System in India • Six Pilot projects on PMUs. • 62 PMUs from 4 Vendors at 60 Locations. • 11 PDCs of 3 Vendors • Integrated at National level. • Extensively used in real time and offline.
- 6. POSOCO, India 6ONE NATION-ONE GRID-ONE FREQUENCY • POSOCO publishes annual report based on its experience in the field of Synchophasor technology. • POSOCO Reports are made public for the benefit of Power system Community. • The second report on “Synchrophasor Initiative in India ” was launched in Dec’2013. • The third Report on “Low Frequency Oscillation” has also been published in Sept-2014. • Report links are : http://posoco.in/2013-03-12-10-34-42/synchrophasors http://indiwams.posoco.in/
- 7. POSOCO, India 7ONE NATION-ONE GRID-ONE FREQUENCY Synchronization and Operation of Large Grids Case Studies
- 8. POSOCO, India 8ONE NATION-ONE GRID-ONE FREQUENCY Case Study 1 : Synchronization of Large Grids on 31st December 2013 Grid Size : 90 GW Own Generation : 32 GW Import over Asynchronous link : 4 GW Grid Size : 36 GW NEW Grid SR Grid 2000 MW 1000 MW 1000 MW • Asynchronous interconnection between NEW Grid and SR grid : • +/- 500 kV, 2 x 1000 MW HVDC Talcher-Kolar bipole. • 2 x 500 MW HVDC back-to-back station at Gazuwaka • 2 x 500 MW HVDC back-to-back station at Bhadrawati • Synchronization of NEW Grid and SR grid : 765 kV Solapur-Raichur circuit S/C (208 km line, Quad Bersimis)
- 9. POSOCO, India 9ONE NATION-ONE GRID-ONE FREQUENCY Regional Grid Interconnection status as on 31st Dec 2013
- 10. POSOCO, India 10ONE NATION-ONE GRID-ONE FREQUENCY Synchronization Aspects Field Setting for Auto-Synchronization Phase angle difference Δδ < 5o Voltage difference ΔV <25 kV Frequency difference Δf <0.1 Hz Same Phase Sequence SPS Envisaged for Secure Operation Power Flow based SPS Safe Isolation SPS Rate of Change of Power SPS Contingency based SPS Synchronization Display in Field Source : Holland-Controls QuickSync Synchronization Display at Control Centre
- 11. POSOCO, India 11ONE NATION-ONE GRID-ONE FREQUENCY • PMU installed on both ends of the Tie Line • Bus PT and Line CT given as input to PMUs • Optical fiber communication between PMU to Regional Control Center. • Displays for visualization / decision making • Frequency Control • Voltage Control • Real-time view at Regional/National Control Centre • Instruction for activation of auto- synchronization at sub-station issued from Control Centre Solapur Raichur National Control Centre PDC Western Regional Control Centre PDC Southern Regional Control Centre PDC Remote Synchroscope for Control Centre using Synchrophasors
- 12. POSOCO, India 12ONE NATION-ONE GRID-ONE FREQUENCY Dashboard at Operator Console in Regional/National Control Centre Phase Angle difference Scope Voltage Magnitude difference Dial Frequency difference Dial 765 kV Frequency Trend 400 kV Frequency Trend 400 kV level Voltage trend of Boundary Buses 765 kV Voltage trend of Boundary Buses
- 13. POSOCO, India 13ONE NATION-ONE GRID-ONE FREQUENCY First Synchronization • Frequency of NEW Grid higher than SR Grid. • Δf = NEW-SR = 0.039 Hz • Max Power flow in First swing : 328 MW export from NEW Grid to SR Grid. • Inter-Area Oscillation Mode detected : 0.2 Hz • Oscillation damped out time : 16 sec. • Synchronization Tool reused subsequently at 14 times. 0.2 Hz Inter-Area Oscillation Tie Line power Flow NEW Grid Frequency SR Grid Frequency Indian Grid Frequency
- 14. POSOCO, India 14ONE NATION-ONE GRID-ONE FREQUENCY Case Study 2 : Controlled Separation of Large Grids on 10th October 2013 • Controlled separation required for facilitating maintenance or changing of SPS scheme or testing of SPS scheme • Decision to issue instructions to open the CB at Boundary sub-station taken by Control Centre Operator with the help of Synchrophasor. • Decision Criteria : • Nominal Frequency • Tie Line flow ≈ 0 MW. • Tie line Flow regulation through HVDC tie • Planned separation carried out for facilitating Planned Outage on 2x1000 MW HVDC Talcher Kolar Bipole.
- 15. POSOCO, India 15ONE NATION-ONE GRID-ONE FREQUENCY Case Study 3 : Islanding Detection and resynchronization • In one case, both Lines tripped on transient fault within few seconds causing system isolation. Frequency Indian Grid NEW Grid SR Grid Angular Separation Islanded Operation Islanding Visualization Different frequency Angle Unwrapping Nil Power Flow on Tie lines Tie Line Flows Both Tie Line Flows Zero
- 16. POSOCO, India 16ONE NATION-ONE GRID-ONE FREQUENCY • Reason for tripping of tie line was found based on voltage and current . • One line tripped on B phase and other on Y phase. • Unsuccessful auto-reclosure attempt due to persisting fault • Resynchronization was completed within 2 hours. R Phase Voltage of 400 kV Solapur Y Phase Voltage of 400 kV Solapur B Phase Voltage of 400 kV Solapur Confirmation/Validation Through SCADA SOE SCADA SOE confirming Breakers Opening Fault Analysis in Real Time
- 17. POSOCO, India 17ONE NATION-ONE GRID-ONE FREQUENCY Case Study 4 : Healthiness of Auto-Synchronization on 24th May 2015 • Healthiness of Auto-synchronization facility at Sub-station need to be checked periodically. • In one case of large grids synchronization, large swings were observed. • High oscillation in Frequency after synchronization. • High power swing on Tie line power flow • large current in the circuit • Large dip in voltage. Voltage 765 kV Solapur Bus Frequency SR Grid NEW Grid Tie Line Power Flow
- 18. POSOCO, India 18ONE NATION-ONE GRID-ONE FREQUENCY • Parameters used for synchronization checked at Control centres using synchrophasr data from both ends of tie lines. • Frequency was Δf ~ 0.033 Hz • Voltage within acceptable limits • Phase sequence was correct • Phase angle difference Δδ > 50o • Feedback given to Utility for checking auto- synchronization Relay. Current on the Tie line Angular Separation
- 19. POSOCO, India 19ONE NATION-ONE GRID-ONE FREQUENCY Summary • Synchrophasor aided Real-time Operation in India • Synchronization of two Large Grids • Safe separation of two Large Grids • Enhanced situational awareness and better decision making • Fault detection, localization and Characterization • Oscillation monitoring • Angular stability monitoring • Utilization in Offline • Improving the SPS design • Feedback to Utilities, Planners and Regulators.
- 20. POSOCO, India 20ONE NATION-ONE GRID-ONE FREQUENCY Email : chandan.wrldc@posoco.in Phone : 022-28315199 20