Transmission Topology Control for System Efficiency Simulations on PJM Real Time Markets

Transcription

1 Transmission Topology Control for System Efficiency Simulations on PJM Real Time Markets Pablo A. Ruiz M. C. Caramanis, E. Goldis, B. Keshavamurthy, X. Li, M. Patel, C. R. Philbrick, A. M. Rudkevich, R. D. Tabors, T. B. Tsuchida. Super Session on Transmission System Efficiency and Reliability Improvements IEEE PES General Meeting Vancouver, BC, July 25, 2013 Copyright 2013 The Brattle Group, Inc. Antitrust/Competition Commercial Damages Environmental Litigation and Regulation Forensic Economics Intellectual Property International Arbitration International Trade Product Liability Regulatory Finance and Accounting Risk Management Securities Tax Utility Regulatory Policy and Ratemaking Valuation Electric Power Financial Institutions Natural Gas Petroleum Pharmaceuticals, Medical Devices, and Biotechnology Telecommunications and Media Transportation

2 Agenda Topology Control Algorithms (TCA): Objectives and Motivation Illustration of Topology Control ARPA-E TCA Project Summary of Simulation Results on PJM RT Markets Concluding Remarks 2

3 TCA Objectives The goal of tractable control of the transmission network topology is to extract more value out of transmission facilities: 1. Significantly lower generation costs 2. Provide additional operational controls manage congestion respond during contingency situations 3. Enable higher levels of variable renewable penetration 4. Increase system reliability TCA Timeframe: between a few days ahead up to real-time 3

4 Congestion in RT Markets: PJM 18-Jul :55 18-Jul :20 18-Jul :30 In the course of a day, congestion patterns and prices can change significantly: Fuel diversity Lack of flexibility in the resource mix Having the ability to dynamically increase transfer capability from low price areas to high price areas will help to relieve congestion, improve dispatch of renewable resources, reduce dispatch costs and increase system flexibility. 4

5 7-bus Example: All Lines Closed 5

6 7-bus Example: All Lines Closed $40/MWh $15/MWh 6

7 7-bus Example: Open Branch Fed by Congested Facility (Line 3 4) Savings! $40/MWh $15/MWh 7

8 Transmission Switching in PJM (Currently) PJM has switching solutions that operators apply to alleviate congestion: The following is a list of potential transmission switching procedures identified by PJM that may assist to reduce or eliminate transmission system congestion. These identified potential transmission switching procedures may or may not be implemented by PJM based upon system conditions, either projected or actual, and ultimately are implemented solely at the discretion of PJM and its Transmission Owners. This posting is for informational purposes only. Consequently, PJM does not guarantee that any of these identified switching procedures will be included in any market-based auctions or in the real time analysis. Accordingly, PJM expressly disclaims any liability for financial consequences that a Member may incur in taking action in reliance on these informational postings. 8

9 ARPA-E TCA Project: Objectives and Focus To develop a full-scale algorithm and software implementation for transmission network topology control operating in conjunction with market engines for security-constrained unit commitment (UC) and economic dispatch (ED); meeting tight computational effort requirements The developed algorithms will be tested in a simulated environment replicating PJM market operations. Focus: Tractability: TCA must work on 13,000+ bus systems Dynamics: look-ahead TC decisions in ED and UC contexts Reliability: security constraints, transient stability and voltage criteria met Impacts: economic and renewable integration benefit evaluation, with expected production cost savings in PJM of over $100 million/year 9

10 Basic TC Software Architecture Topology, Dispatch, Commitment, Marginal Costs Topology Control Contingency + Voltage + Stability Evaluation * Voltage, MVA and Stability Assessment: Feasible/Infeasible, Constraints to Return to Feasibility * The simulations in this presentation include contingency evaluation and enforcement, but do not include voltage or transient stability evaluation 10

11 PJM RT Market Test Systems Based on one operational power flow snapshot per hour (interval minutes) for three selected, representative historical weeks in 2010 (summer, shoulder and winter weeks). Data taken from the power flows: Transmission topology Branch limits Fixed interface constraint limits at historical value used by PJM for the same interval Unit commitment Fixed dispatch of hydro, wind, landfill, nuclear and reliability must-run thermal units for the interval Loads, losses, interchange Approximately 13,400 nodes, and dispatchable thermal PJM units About 3500 monitored facilities and 6000 single and multi-element contingencies Generation economic and constraint data from real-time market Network service requirements for all loads and generators No reserve requirements implemented in these models Model setup and results reviewed by PJM 11

12 TC Economic Performance Metrics and Preliminary Results Production Cost Savings = production cost without TCA (full topology) production costs with TCA Cost of Congestion = production cost with transmission constraints production costs without transmission constraints The production or market Cost of Congestion defined above (different from congestion rent, which can be many times larger) provides an upper bound on the maximum systemwide Production Cost Savings attainable with any transmission efficiency approach or technology The estimated annual savings in PJM RT markets under 2010 conditions are over $100 million Based on the production cost savings resulting from the weekly simulations* * Representative weeks of summer, winter and shoulder seasons were simulated. 12

13 Notes on the TC Economic Performance Realistic criteria: Solution time: 5 minutes (computation limit) for each interval solution Cost of switching: minimum savings of $100 per open or close breaker operation required to switch Reliability Full security evaluation (6000 contingencies) and enforcement (included in the 5 minute time limit) Starting conditions: same historical conditions as the RT markets Conservative estimate: Savings are in addition to any topology control action PJM implemented in that week Standard, commercially available server (two 4-core 2.66-GHz Intel Xeon processors, 24 GB of RAM) Many potential topology change options are not visible in the reduced busbranch power flow models (e.g., opening bus ties) 13

14 Number of Topology Changes per Hour (Preliminary) Week Metric Branches Open Switched Opened Switched Closed Summer Maximum Median Winter Maximum Median Different due to weekly start with full topology which requires additional openings and fewer closings 14

15 Number of Topology Changes per Hour (Preliminary) A daily cycle of number of breakers open is very evident in the summer week, with the largest number of breakers opened corresponding to hours with lower load (early morning), and with more re-closings as load increases to meet security constraints. Number of breakers open per hour seems to increase during Winter week, indicating that the average number of branches opened has not reached a steady state during the week (this is under investigation, including looking at the impacts of different starting topologies for the weekly simulations). Initially, (Sunday), topology did not change significantly since congestion was limited. 15

16 Summary of Breakers Operated (Preliminary) Nominal kv Summer Week Winter Week <200 kv 46% 51% 230 kv 26% 22% 345 kv 11% 14% 500 kv 11% 9% 765 kv 6% 4% 765 kv breakers are mostly opened during low load periods, such as during the weekend or very early mornings, when they are not needed for reliability, are lightly loaded, and may cause overvoltages. 16

17 Summary of Flow on Breakers Operated (Preliminary) Breakers Switched Open Summer Week Breakers Switched Close nominal kv median flow MW median flow % nominal kv median flow MW median flow % 115kV 47 24% 138 kv 51 20% 230 kv % 345 kv % 500 kv % 765 kv % 115kV 58 31% 138 kv 89 31% 230 kv % 345 kv % 500 kv % 765 kv % Flows opened or closed are well below normal facility ratings, and orders of magnitude below short circuit ratings, reducing the expected maintenance required to sustain the increased breaker duty 17

18 Concluding Remarks and Work in Progress Most system operators employ TC today, mainly on an ad-hoc basis using operators previous experience The TCA project will provide practical technology to enable transparent, consistent and routine implementation of topology control with significant efficiency gains The technology is being assessed on detailed models of PJM markets, with review from PJM staff Hourly security-constrained TCA solutions are obtained in few minutes Simulations on detailed PJM RT market models indicate that annual PJM savings are over $100 million (under 2010 conditions) Impacts on DA markets are expected to be significantly larger, since TC could enable more efficient unit commitment, and will be analyzed next Off-line advisory tool planned to be ready for deployment by mid

19 Contact Info Pablo A. Ruiz The Brattle Group and Boston University, (617) Please sign up for the TCA periodic updates! References [1] P. A. Ruiz, J. M. Foster, A. Rudkevich and M. C. Caramanis, Tractable transmission topology control using sensitivity analysis, IEEE Transactions on Power Systems, vol. 27, no. 3, Aug 2012, pp [2] P. A. Ruiz, A. Rudkevich, M. C. Caramanis, E. Goldis, E. Ntakou and C. R. Philbrick, Reduced MIP formulation for transmission topology control, in Proc. 50 th Allerton Conference on Communications, Control and Computing, Monticello, IL, October [3] J. M. Foster, P. A. Ruiz, A. Rudkevich and M. C. Caramanis, Economic and corrective applications of tractable transmission topology control, in Proc. 49 th Allerton Conference on Communications, Control and Computing, Monticello, IL, September [4] P. A. Ruiz, J. M. Foster, A. Rudkevich and M. C. Caramanis, On fast transmission topology control heuristics, in Proc IEEE Power and Energy Society General Meeting, Detroit, MI, July