Optimal Power Flow Packages Requirements and Experiences
The purpose of an Optimal Power Flow (OPF) function is to schedule the power system controls to optimize an objective function while satisfying a set of nonlinear equality and inequality constraints. The equality constraints are the conventional power flow equations; the inequality constraints are the limits on the control and operating variables of the system. Mathematically the OPF can be formulated as a constrained nonlinear optimization problem.
Practical, constrained active and reactive OPF problems have complicated non-analytical, non-static and partially discrete formulations. At the same time, however, most OPF development efforts have centered on the mathematical optimization of simple classical OPF formulations, expressed in smooth nonlinear programming form. As they stand, these formulations are far too approximate and incomplete descriptions of the real life problems to be adequate for on-line use. Furthermore, at the present time they cover only a limited area of system operations.
This paper will address specific operational requirements that need to be met for a successful implementation and use of an on-line OPF package. These include a) response time requirements, b) robustness with respect to starting point, c) expansion of the scope of the OPF problem to be able to solve realistically posed problems, d) infeasibility detection and handling, e) ineffective “optimal” rescheduling, f) discrete modeling, g) development of techniques/guidelines for selecting an “optimal trajectory” that steers the power system as reliably and as far as possible in the direction of the optimum, h) modeling of contingency constraints, i) consistency of OPF with other on-line functions, j) data quality and other practical requirements, k) maintenance and MMI and 1) on-line OFF based external modeling.
Over the last two decades several approaches have been proposed to solve the constrained nonlinear OPF problem. A straightforward solution could be to use quadratic programming Other approaches that have been implemented with various degrees of success include, Generalized Reduced Gradient, Newton’s method, Linear Programming and Interior Point techniques. Based on the above requirements, experience and conclusions reached from the development and/or use in a practical environment of these techniques will also be discussed.
KeywordsPower System Power Flow Optimal Power Flow Energy Management System Variable Swap
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- 1.J. Carpentier: Contribution a.’ l’etude du Dispatching Economique; Bulletin de la Societe Francaise des Electriciens, Vol. 3, pp. 431–447. Aug. 1962.Google Scholar
- 2.H.W. Dommel and W.F. Tinney: Optimal Power Flow Solutions; IEEE Transactions on Power Apparatus and Systems, Vol. PAS-87, pp. 1866–1876, Oct. 1968.Google Scholar
- 3.H.H. Happ: Optimal Power Dispatch - A Comprehensive survey; IEEE PAS, Vol. PAS-96, pp. 841–854, May/June 1977.Google Scholar
- 4.B. Stott, O. Alsac, and A. Monticelli: Security Analysis and Optimization; Proceedings of IEEE, December 1987.Google Scholar
- 5.J. Carpentier: Towards a Secure and Optimal Automatic Operation of Power Systems; PICA 87, pp. 2–37.Google Scholar
- 7.R.C. Burchett, H.H. Happ, D.R. Vierath: A Quadratically Convergent Optimal Power flow; IEEE Transactions on Power Apparatus and Systems, Vol. PAS-103, pp. 3267–3276, November 1984.Google Scholar
- 8.H. Glavitsch and M. Spoerry: Quadratic loss formula for reactive dispatch; IEEE Transactions on Power Apparatus and Systems, vol. PAS-102, pp. 3850–3858, Dec. 1983.Google Scholar
- 9.B. Stott and E. Hobson: Power System Security Control Calculations Using Linear Programming, Parts I and II; IEEE Transactions on Power Apparatus and Systems, vol. PAS-97, pp. 1713–1731, Sept./Oct. 1978.Google Scholar
- 10.B. Stott and J.L. Marinho: Linear Programming For Power System Network Security Applications; IEEE Transactions on Power Apparatus and Systems, vol. PAS-98, pp. 837–848, May/June 1979.Google Scholar
- 11.K.R.C. Mamandur and R.D. Chenoweth: Optimal Control Of Reactive Power Flow For Improvements In Voltage Profiles and For Real Power Loss Minimization; IEEE Transactions on Power Apparatus and Systems, vol. PAS-100, pp. 3185–3193, July 1981.Google Scholar
- 12.K.R.C. Mamandur: Emergency Adjustments To VAR Control Variables To Alleviate Over-Voltages, Under Voltages and Generator VAR Limit Violations; IEEE Transactions on Power Apparatus and Systems, vol. PAS-101, pp. 1040–1047, May 1982.Google Scholar
- 13.D. I. Sun, B. Ashley, B. Brewer, A. Hughes, and W.F. Tinney: Optimal Power Flow By Newton Approach; IEEE Transactions on Power Apparatus and Systems, vol. PAS-103, pp. 2864–2880, Oct. 1984.Google Scholar
- 14.G.A. Maria and J.A. Findlay: A Newton Optimal Power Flow Program For Ontario Hydro EMS; IEEE Transactions on Power Apparatus and Systems, vol. PWRS-2, pp. 576–584, Aug. 1987.Google Scholar
- 15.K.A. Clements, P.W. Davis, K.D. Frey: Treatment of Inequality Constraints in Power System State Estimation; IEEE Winter Meeting 1992, Paper 92WM 111–5 PWRS.Google Scholar
- 16.L.S. Vargas, U.H. Quintana, A. Vannelli: A Tutorial Description of an Interior Point Method and its Applications to Security-Constrained Economic dispatch; IEEE Summer Power Meeting 1PP2, Paper 92SM 416–8 PWRS.Google Scholar
- 17.O. Alsac, J. Bright, M. Prais, B. Stott: Further Developments in LP-Based Optimal Power Flow; IEEE Transactions on Power Apparatus and Systems, Vol. 5, No. 3, pp. 697–711, August 1990.Google Scholar
- 19.A.D. Papalexopoulos, C.F. Imparato and F.F. Wu: Large-Scale Optimal Power Flow: Effects of Initialization, Decoupling and Discretization; IEEE Transactions on Power Apparatus and Systems, Vol. PWRS-4, pp. 748–759, May 1989.Google Scholar
- 20.D.S. Kirschen and H.P. Van Meeteren: MW/Voltage Control in a Linear Programming Based Optimal Power Flow; IEEE Transaction on Power Apparatus and Systems, Vol., PWRS-3, pp. 481–489, May 1988.Google Scholar
- 21.S.V. Venkatesh, E. Liu, A.D. Papalexopoulos: A Least Squares Solution For Optimal Power Flow Sensitivity Calculations; IEEE Transactions on Power Apparatus and Systems, Vol. 7, No. 3, pp. 1394–1401, August 1992.Google Scholar
- 22.P.E. Gill, W. Murray, M.H. Wright: Practical Optimization; Academic Press, 1981.Google Scholar
- 24.W.F. Tinney, J.M. Bright, K.D. Demaree and B.A. Hughes: Some Deficiencies in Optimal Power Flow; IEEE PICA Conference Proceedings, pp. 164–169, Montreal, May 1987.Google Scholar
- 25.E. Liu, A.D. Papalexopoulos, W.F. Tinney: Discrete Shunt Controls in A Newton Optimal Power Flow; IEEE Winter Power Meeting 1991, Paper 91WM 041–4 PWRS.Google Scholar
- 26.W.C. Merritt, C.H. Saylor, R.C. Burchett and H.H. Happ: Security Constrained Optimization–A Case Study; IEEE Transactions on Power Apparatus and Sytems, Vol. PWRS-3, pp. 970–977, Aug. 1988.Google Scholar
- 27.IEEE Current Operating Problems Working Group Report: On-Line Load Flows From a System Operator’s Viewpoint; IEEE Transactions on Power Apparatus and Systems, vol. PWRS-102, pp. 1818–1822, June 1983.Google Scholar
- 28.M. Innorta and P. Marannino: Very Short Term Active Power Dispatch With Security Constraints; in Proceedings IFAC Symposium on Planning and Operation of Electric Energy Systems ( Rio de Janeiro, Brasil, July 1985 ), pp. 379–386.Google Scholar
- 29.J. Carpentier: Optimal Power Flows: Uses, Methods and Developments; in Proceedings IFAC Symposium on Planning and Operation of Electric Energy Systems ( Rio de Janeiro, Brazil, July 1985 ), pp. 11–21.Google Scholar
- 30.R. Bacher and H.P. Van Meeteren: Real-Time Optimal Power Flow in Automatic Generation Control; IEEE Transactions on Power Apparatus and Systems, Vol. PWRS-3, pp. 1518–1529, Nov. 1988.Google Scholar
- 31.N. Karmarkar: A New Polynomial Time Algorithm for Linear Programming; Combinatorica, May 1984.Google Scholar
- 32.P.E. Gill, W. Murray, M.A. Saunders: Interior-PointMethods for Linear Programming: A Challenge to the Simplex Method; Technical Report SQL 88–14, Department of Operations Research, Stanford University, 1988.Google Scholar
- 33.A. Monticelli, E. Liu: Adaptive Movement Penalty Method for the Newton Optimal Power Flow; presented at the IEEE/PES 1990/Winter Meeting, Atlanta, Georgia, February 4–8, 1990.Google Scholar