Engineering Conferences International ECI Digital Archives Modeling, Simulation, And Optimization for the 21st Century Electric Power Grid Proceedings Fall 10-22-2012 Improving Transmission Asset Utilization Through Advanced Mathematics and Computing Henry Huang Pacific Northwest National Laboratory Ruisheng Diao Pacific Northwest National Laboratory Shuangshuang Jin Pacific Northwest National Laboratory Yuri Makarov Pacific Northwest National Laboratory Follow this and additional works at: http://dc.engconfintl.org/power_grid Part of the Electrical and Computer Engineering Commons Recommended Citation Henry Huang, Ruisheng Diao, Shuangshuang Jin, and Yuri Makarov, "Improving Transmission Asset Utilization Through Advanced Mathematics and Computing" in "Modeling, Simulation, And Optimization for the 21st Century Electric Power Grid", M. Petri, Argonne National Laboratory; P. Myrda, Electric Power Research Institute Eds, ECI Symposium Series, (2013). http://dc.engconfintl.org/power_grid/8 This Conference Proceeding is brought to you for free and open access by the Proceedings at ECI Digital Archives. It has been accepted for inclusion in Modeling, Simulation, And Optimization for the 21st Century Electric Power Grid by an authorized administrator of ECI Digital Archives. For more information, please contact franco@bepress.com.
Modeling, Simulation and Optimization for the 21st Century Electric Power Grid October 21-25, 2012 Lake Geneva, Wisconsin Improving Transmission Asset Utilization through Advanced Mathematics and Computing Henry Huang, Ruisheng Diao, Shuangshuang Jin, Yuri Makarov Pacific Northwest National Laboratory October 22, 2012 1
Transmission congestion an ever increasing challenge Incur significant economic cost 2004: $1 billion cost at California ISO due to congestion and reliability must-run requirements [1] 2008: >$1.5 billion congestion cost at New York ISO [2] Prevent wind integration Wind generation curtailment due to transmission congestion Congestion will become worse and more complicated Uncertainty, stochastic power flow patterns due to changing generation and load patterns, increased renewable generation, distributed generation, demand response and the increasing complexity of energy and ancillary service markets and Balancing Authority (BA) coordination. [1] California Energy Commission, Strategic Transmission Investment Plan, November 2005 [2] NYISO, Congestion Analysis Summary for 2008. 2
Building more transmission lines is not the best option Transmission build-out lags behind load growth 1988-98: load grew by 30%, transmission grew by only 15% [3] Resulting in a transmission grid that must operate closer to the maximum limit, and this is expected to compound as demand for electricity is expected to double by 2050. Transmission expansion is constrained by: Financial and cost-recovery issues Right-of-way and Environmental considerations [3] U.S. Department of Energy, The Smart Grid: An Introduction. 3
Possibility of utilizing more of what we already have Measurement of Transfer Capacity Example - California Oregon Intertie (COI) [4] Path Ratings Thermal rating 10,500 MW U75, U90 and U(Limit) U75 % of time flow exceeds 75% of OTC (3,600 MW for COI) Stability Rating (Transient Stability and Voltage Stability) 4,800 MW 75% 90% 100% % of OTC U90 - % of time flow exceeds 90% of OTC (4,320 MW for COI) U(Limit) - % of time flow reaches 100% of OTC (4,800 MW for COI) [4] Western interconnection 2006 congestion management study 4
Real-time path rating Current Path Rating Practice and Limitations Offline studies months or a year ahead of the operating season Worst-case scenario Ratings are static for the operating season The result: conservative (most of the time) path rating, leading to artificial transmission congestion Real-Time Path Rating On-line studies Current operating scenarios Ratings are dynamic based on real-time operating conditions The result: realistic path rating, leading to maximum use of transmission assets and relieving transmission congestion 5
Real-time path rating case studies IEEE 39-bus power system 26% more capacity without building new transmission lines WECC COI Line Full study with realistic case and parameters Peak rating increases 30% 2500 Transfer limit of a critical path, MW 2000 1500 1000 500 Real-time Path Rating 25.74% more energy transfer using real-time path rating Offline path rating, current practice 30% increase 0 5 10 15 20 Time, hour 6
Benefits of real-time path rating Increase transfer capability of existing power network and enable additional energy transactions $15M annual revenue for a 1000-MW rating increase for one transmission path in the WECC system, even if only 25% of the increased margin can be used for just 25% of the year Reduce total generation production cost $28M annual product cost saving for only one path Avoid unnecessary flow curtailment for emergency support, e.g. wind uncertainties Enable dynamic transfer Enhance system situational awareness Defer building new transmission lines 7
Computational feasibility of real-time path rating Computational challenges are the major limiting factor in the current path rating practice ~24 hours for one path rating Target: 5-10 minutes Path rating studies involve many runs of transient stability simulation and voltage stability simulation Target: seconds for each run Real-Time Measurements State Estimation Transient Stability Simulation Voltage Stability Simulation Thermal Rating Transient Stability Rating Voltage Stability Rating min Real-Time Path Rating 8
Fast transient simulation via computational enhancements Achieved 26x speed-up for a WECC-size system (16,000-bus) using 64 threads compared to the sequential version using 1 thread. Only took 9 seconds to run the 30 seconds WECC-size simulation with 64 threads, which is 20 seconds ahead of the real time, and 13x faster than today s commercial tools (which needs 120 seconds after considering the difference between CPU configurations). 250 50 45 200 40 Time in seconds 150 100 50 Speedup 35 30 25 20 15 10 Reduced Admittance Matrix Computing Time-Stepping simulation Total 0 1 2 4 8 16 32 64 Number of threads 5 0 1 2 3 4 5 6 7 Number of threads 9
Non-iterative voltage stability simulation via mathematical advancements Traditional Iterative Method V V 0 V critical 0 P L A... B C P L0 Power Load Flow P max V2 Real Eigenvalue-based Non-Iterative Method Static Voltage Stability Boundary in State Space [2 machine 3 bus system] 2 1.5 1 0.5 0 0.5 1 1.5 2 2 1.5 X2 X1 X max : λ J 1 (X 0 ) J(X 1 )+ I X = 1+ λ 1 1 0.5 ( ) X 0 λ 1 X 1 0 V1 Imag 0.5 1 1.5 2 Computational time Speed-up w.r.t. Commercial Tool Iterative Method Eigenvaluebased Non- Iterative Method Enhanced Eigenvaluebased Non- Iterative Method 61 315 sec 4 10 sec 2 4 sec --- 6 78 times 15 150 times 10
Summary Fast transient stability and voltage stability simulations through computational and mathematical advancements are proven feasible. Fast simulations enable real-time path rating. Real-time path rating minimizes conservativeness while still maintaining stability. Real-time path rating relieves transmission congestion by increasing usable transmission capacity. Real-time path rating improves asset utilization by ~30% in the tested cases. Improved asset utilization brings financial benefits in production cost saving and transaction revenue increase. Improved asset utilization also facilitates integration of renewables (and other new technologies) by minimizing curtailment. 11
Where we go from here Grid is transitioning in three fusions: Fusion of operation and planning to enable more seamless grid management and control Remove overhead in communication between operation and planning Improve response when facing emergency situations Integration of transmission and distribution in managing two-way power flows Understand the emerging behaviors in the power grid due to smarter loads, mobile consumption, and intermittent generation Interdependency between power grid and data network Bring data to applications efficiently and reliably Enable all-hazard analysis GridOPTICS methods and tools to support these three fusions http://gridoptics.pnnl.gov/ Protected Information Proprietary Information 12
Questions? Zhenyu (Henry) Huang Pacific Northwest National Laboratory zhenyu.huang@pnnl.gov 509-372-6781 13