Showing papers on "Economic dispatch published in 1985"
TL;DR: In this paper, the authors present a new algorithm to find the optimal unit commitment and economic dispatch (UC/D) for a large hydrothermal power system, which is a large nonlinear, mixed integer optimization problem involving over 16,800 integer variables.
Abstract: In this paper we present a new algorithm to find the optimal unit commitment and economic dispatch (UC/D) for a large hydrothermal power system. Mathematically, this is a large nonlinear, mixed integer optimization problem involving over 16,800 integer variables for a system having 100 thermal units with a 1-week scheduling horizon. We use a dual programming approach to solve a separate optimal control problem for each thermal unit and for each set of coupled hydro units. The algorithm has been tested on a 100 thermal unit/6 hydro unit system having a 168-hour scheduling period, and will find solutions that are within 0.1 to 0.25 percent of the optimal dual cost. We report computational results for a system modeled after the New York Power Pool.
108 citations
TL;DR: Improvements in speed of the optimal power flow and the inclusion of the latter into a closed loop secure economic dispatch are presented and a new load flow technique with “implicit active reactive coupling” is presented.
55 citations
TL;DR: In this article, an extremly fast, simple, efficient and reliable economic dispatch algorithm is presented, which utilizes a closed form expression for the calculation of the Lambda, as well as taking care of total transmission loss changes due to generation change, thereby avoiding any iterative processes in the calculations.
Abstract: An extremly fast, simple, efficient and reliable economic dispatch algorithm is presented. The algorithm utilizes a closed form expression for the calculation of the Lambda, as well as taking care of total transmission loss changes due to generation change, thereby-avoiding any iterative processes in the calculations. The closed form expression presented for Lambda can be used with any type of incremental transmission loss calculation. For this algorithm, penalty factors are derived based upon the Newton's method. An efficient method to implement the algorithm in power control centers is discussed. The algorithm presented has excellent convergence properties.
48 citations
TL;DR: In this article, the transient phenomena associated with the loss of generation contingency is described and a method of determining the subset of generators that participate in governor load flow is described based on this discussion.
Abstract: The transient phenomena associated with the loss of generation contingency is described in this paper. The propagation of the disturbance, the time instant at which the inertial load flow captures a snapshot of the transient, and the time instant at which the governor load flow captures a snapshot of the transient is described. A method of determining the subset of generators that participate in governor load flow is described based on this discussion of the propagation and evolution of the transient phenomena associated with loss of generation contingencies. Finally, the application of inertial and governor load flow in planning is discussed. A description of the inertial and governor load flow program, developed for EPRI and residing in the EPRI Software Center, is described.
42 citations
TL;DR: A straight forward and computationally efficient method is presented for calculating and sending ``economic'' Area Control Error (ACE) signals to three operating companies in the Texas Utilities (T.U.) System.
Abstract: A straight forward and computationally efficient method is presented for calculating and sending ``economic'' Area Control Error (ACE) signals to three operating companies in the Texas Utilities (T.U.) System. The method requires T.U. system ACE and each operating company's total generation and then mathematically computes each area's desired generation. The difference between the desired generation and the actual generation for each area is its's economic ACE. The method features a sorted-table approach to economic dispatch and calculates the economic ACE every five seconds. It has been thoroughly tested and implemented on the Texas Utilities System.
31 citations
TL;DR: In this article, the authors present the concept of participation factors load flow and apply it to the economic dispatch problem, where the quantities specified or controlled at the NG generation buses are the NG participation factors instead of NG-1 real generations.
Abstract: This paper presents the concept of the participation factors load flow and applies it to the economic dispatch problem. The participation factors load flow consists of a load flow model where the quantities specified or controlled at the NG generation buses are the NG participation factors instead of NG-1 real generations. This formulation permits us to more realistically model the closed loop mode of generation dispatch used by control centers today. In contrast most modern economic dispatch algorithms based on the conventional load flow produce an open loop dispatch which cannot be directly implemented in the closed loop participation factors dispatch mode without additional computations. The numeric and analytic properties of this new load flow formulation are very similar to those of the conventional load flow with one significant difference, a slack bus need not be defined, a property which has various advantages. The new model permits the development of a decoupled economic dispatch scheme which directly computes the participation factors and separates the dispatching of real power quantities quite naturally from reactive power, voltage variables and transformer parameters.
28 citations
TL;DR: In this paper, a preventive control program for voltage and reactive power dispatch is developed to enhance a system's capability to cope with outages, not only the base case but also associated contingency cases have been considered.
Abstract: A preventive control program for voltage and reactive power dispatch is developed to enhance a system's capability to cope with outages. In this program, not only the base case but also associated contingency cases have been considered. Therefore, it is referred to as the Global VAR Dispatch Method.
18 citations
TL;DR: Computational experience indicates that the method is highly efficient and is capable of solving realistic problems in elapsed times that are compatible with online applications using minicomputer hardware.
14 citations
TL;DR: An on-line economic power dispatch method with security is presented; it maintains the advantage of rapid calculation possessed by the classical dispatch approach and at the same time settles N and N — 1 security problems.
13 citations
TL;DR: In this article, a control strategy for an AC/DC/AC interface to smooth or limit wind farm output is investigated, and an optimal level to which the wind output should be limited is found in terms of the distribution of wind power output and the relative cost of the fast acting and base loaded units.
Abstract: A control strategy for an AC/DC/AC interface to smooth or limit wind farm output is investigated. The need to follow rapid power variation from uncontrolled wind farms with expensive gas turbines limits the amount of penetration of wind energy systems in existing utilities. An AC/DC/AC interface makes it possible to limit the power variations from the wind farm. An optimal level to which the wind output should be limited is found in terms of the distribution of wind power output and the relative cost of the fast acting and base loaded units. Using the optimal cutting point for the wind output each wind farm can be included in the economic dispatch calculation. The economic advantage of limiting wind power output is demonstrated on an example system. Using a hypothetical system it is shown that wind penetrations as high as 16.75% may be economical using the optimal strategy made possible by the AC/DC/AC interface.
9 citations
TL;DR: A mathematical framework is described for the solution ot the economic dispatch problem with security constraints, which can take into account the system corrective capabilities after the outage has occurred and has the same security level as the usual security-constrained dispatch, but with lower operating costs.
TL;DR: In this paper, the optimal load flow problem is formulated as a stochastic programming problem, where the electricity demand at each node is treated as a random variable with a given probability distribution function.
Abstract: The optimal load flow problem is to determine the allocation of electricity demand among the committed generating units to minimize the total operating costs subject to various physical and technological constraints. If only the real power generation is to be determined and the reactive power generation is assumed fixed, then the problem is known as the economic dispatch problem, It is extensively used in the real time management of electrical power systems. In the existing formulations of the economic dispatch problem, the electricity demands at nodes of the transmission network are treated as given, that is, the point estimates of demand values are used. In this paper, the electricity demand at each node is treated as a random variable with a given probability distribution function. This assumption leads to a stochastic programming model which consists of minimization of a convex objective function subject to upper and lower bounds on decision variables. The development of this model is presented in the...
TL;DR: This paper presents an efficient and reliable algorithm for solving an economic load dispatch problem of interconnected systems in which tie-line flows are coupling variables and the decomposition method is robust whereas previously existing algorithms for the problem above are not.
Abstract: This paper presents an efficient and reliable algorithm for solving an economic load dispatch problem of interconnected systems. The proposed algorithm is a feasible type decomposition method in which tie-line flows are coupling variables. Since mathematical programming techniques underlie the proposed algorithm, the decomposition method is robust whereas previously existing algorithms for the problem above are not. In the proposed algorithm, information transmitted through communication channels is reduced for the purpose of computational efficiency. Since the proposed algorithm is a feasible method, a feasible solution is obtained at each coordinating iteration and, the algorithm can be terminated prior to optimality, if desired. Numerical test has been carried out for a real interconnected system composed of six systems. The test result shows the effectiveness of the proposed algorithm.
TL;DR: In this article, a dynamic optimal economic dispatch policy was developed on the basis of a stochastic availability model and a piece-wise constant incremental fuel cost model using a dynamic nonlinear optimization problem.
01 Jan 1985
TL;DR: In this article, a dynamic optimal economic dispatch policy based on a stochastic availability model of large-scale power systems and a piece-wise constant incremental fuel cost model was developed.
01 Jan 1985
TL;DR: A distributed computer system designed for research into the distributed control of electrical power generation and transmission networks has been described and computational results indicate that overall savings in solution times may be achieved even with a communication system of relatively low bandwidth.
Abstract: This paper has described a distributed computer system which has been designed for research into the distributed control of electrical power generation and transmission networks. A particular aspect of the control problem, the economic dispatch of generator outputs, has been discussed, and the application of a decomposed solution algorithm has been considered. The computational results which have been obtained to date are favourable and indicate that overall savings in solution times may be achieved even with a communication system of relatively low bandwidth.
TL;DR: The mathematical model for the decentralized power pool is presented as a generalized minimum cost flow problem with convex node production costs, and a new combinatorial optimization algorithm, Maximum Path Return method, (MPR) is shown suitable as a substitute for the brokerage method.
01 Jan 1985
TL;DR: The multilevel control techniques used in this work distribute between two control levels the calculation of optimum set points of the system by decomposition-coordination of the overall optimization problem.
Abstract: The economical short term dispatching of hydroelectric system is a very actual problem and its resolution consists in solving a large scale optimization problem; the classic methods fail when the complexity and the dimension of the problem are very large. The multilevel control techniques used in this work distribute between two control levels the calculation of optimum set points of the system by decomposition-coordination of the overall optimization problem.
TL;DR: A new technique of Economic Dispatch for allocating generation in a power system using a modified version of the fast power flow method developed earlier is found to be fast, reliable and suitable for on-line implementation.
Abstract: This paper presents a new technique of Economic Dispatch for allocating generation in a power system. Penalty factors associated with generating units are calculated from a particular eigenvector of the transposed Jacobian matrix which is obtained while solving the load flow problem using a modified version of the fast power flow method developed earlier. The evaluation of the required eigenvector is simple and straightforward as the order of the Jacobian matrix is equal to the number of voltage controlled busbars in the system. The optimal allocation of each generating unit for the given demand on the system is obtained by solving the co-ordination equations along with load flow problem. The technique is found to be fast, reliable and suitable for on-line implementation.
TL;DR: In this article, a decomposition approach to the operation scheduling of hydrothermal power systems is proposed and numerically applied to a network in the Southest of Brazil, where the methodology proposed decomposes the overall system into two decoupled subsystems (hydraulic and thermal) introducing the concept of hydraulic subsystem effectiveness with respect to the demand meeting.
01 Jan 1985
TL;DR: An extremlyfast, simple, efficient andreliable economic dispatch algorithm is presented, which has excellent-convergence properties and can be used with' any type of incremental transmission loss calculation.
Abstract: An extremlyfast,simple, efficient andreliable economic dispatch algorithm ispresented. Thealgorithm utilizes a closedformexpression for the calculation of the Lambda,as well'as takingcare of total transmission losschangesdue to generation change, thereby-avoiding,anyiterative processesin the calculations. Theclosedformexpression presented for Lambdacan be usedwith'anytypeof incremental transmission losscalculation.For thisalgorithm, penaltyfactorsare derivedbasedupontheNewton's method.Anefficient methodtoimplement thealgorithm inpowercontrol centersisdiscussed'. The algorithm presented hasexcellent-convergence properties.