The Use of VSC-Based BtB as Grid Shock Absorber

Transcription

1 The Use of VSC-Based BtB as Grid Shock Absorber Abdel-Aty Edris IEEE GM July 08

2 Voltage-Sourced Converter A Building Block for New Transmission Controllers Vo Transm ission lineline Transm ission VL L V0 V0 Gate Turn Off Switch Transformer Transformer I I inductance inductance Voltage Sourced sourced In verter inverter GTO, GCT, IGBT V dv c dc Voltage sou rce converter w ith controlled output voltage If V L =V 0, I = 0 If V L <V 0, I = cap acitive If V L >V 0, I = inductive DC DC capacitor capacitor Pulse-Width Modulation Three-Level Switching 2

3 VSC-Based BtB as a Grid Shock Absorber (GSA) VSC-Based BTB Area 1 MW The idea! Area 2 V V V 1 V 2 Coupling Transformer Coupling Transformer AT AC TERMINAL 1 Q 1 V g Generator 1 ac terminal V V V gc ga gb System variables V g Generator 2 ac terminal V V V gc ga gb AT AC TERMINAL 2 Q 2 P 1 < 0 Q 1 > 0 P 1 > 0 Q1 > 0 P 2 < 0 Q 2 > 0 P 2 > 0 Q2 > 0 P 1 < 0 Q 1 < 0 P 1 > 0 Q 1 < 0 P 1 Control P 2 < 0 Q 2 < 0 P 2 > 0 Q 2 < 0 P 2 MVA limit DC terminal C V dc + Switching converter Parameter setting References I dc P 1 = -P 2 Switching converter + C V dc DC terminal MVA limit 3

4 Grid Segmentation and Grid Shock Absorbers 4

5 Grid Segmentation and Grid Shock Absorbers Orange Green Red Blue - VSC-Based -existing concatenated - future ac long lines BtBs:Grid & haul converted dc Shock lines Absorbers to ac dc lines Grid Shock Absorber 5

6 Proof of Concept Study On Eastern Interconnection (EI) GSA GSA B A GSA C D GSA C Outside World E Ontario PJM D Hydro Quebec B New York A New England 6

7 Impact of Substantial Generation Trips on Power Flows Case 2 With ac links MW G 1625 MW 100 MW A B G D 2700 MW Voltages (%) (a) Case 2 With dc links C Time (s) MW 1150 MW G 1550 MW A G 2700 MW Voltages (%) (b) 2775 MW MW G B 150 MW D Time (s) 150 MW C Selected bus voltages with ac ties (a) and dc links (b) in place. Voltages are not from the same buses in the two cases. 7

8 Segmentation and Grid Shock Absorber: R&D Project Opportunity Grid Reliability and Efficiency Enhancement Network (GreenTM) Transmission Interconnection 8

9 Overall issue or problem to be addressed Increased robustness and integrity of transmission grid Increased transmission efficiency Green House Gas (GHG) management. Proposed Tasks Select a benchmark transmission grid, representing a Transmission Interconnection, e.g. Western Interconnection Identify cascading failure risks under particular operating conditions and contingencies Identify boundary configurations for improved robustness of the grid against cascading failures. These boundaries determine candidate sectors to be asynchronously linked using the Grid Shock Absorber concept, Voltage Sourced Converter (VSC)-based ties. Run test simulations to assure expected segmented behavior Assess grid reconfiguration costs and benefits Evaluate economic feasibility with Improved market operations 9

10 Research and Development Opportunity Help the industry meet the following transmission needs: Reliability enhancement: Minimizing grid exposure to cascading system failures and outages Efficiency enhancement: Facilitating efficient scheduling and power trade by improving grid utilization at reduced costs of service GHG management: Least-cost access to distant resources to meet pending limits on GHG emissions 10

11 The proposed R&D effort will be guided by four design principles: Maximum utilization of existing and planned ac transmission infrastructures Superposition of a network of HVDC gates within the targeted grid to meet the three requirements Reliability, Efficiency and GHG Management The quality of the transmission services provided by the modified grids will equal or exceed what is expected without the implementation of the GREEN TM Project Meeting all existing NERC, regional, and local planning and operating criteria 11

12 Grid Reliability and Efficiency Enhancement Network (GREEN) Expected Results: Inter-sector power-flow controllability Higher line loadings Increased ROW power densities Consolidation of investments in reliability and market enhancements Reduced cascading blackouts Improved access to resources for better GHG management 12

13 Project Status Proof of Concept Product ID # Technical Assessment of Grid Shock Absorber Concept, IEEE Power & Energy Magazine, January/February 2008 Segmentation with Grid Shock Absorbers for Reliability of Large Transmission Interconnections?? 13

14 THANKS FOR YOUR ATTENTION Questions? Together..Shaping the Future of Electricity 14