Fuel Resource Scheduling, Part II: Constrained Economic Dispatch

The constrained economic dispatch, subject to fuel supply and consumption constraints and unit operating constraints, with shared and mixed fuels, is formulated as a minimum cost network flow problem. Different algorithms are presented to handle the linear and nonlinear input/output characteristics of the units. The test results for a 17 unit/17 contract test system indicate that the proposed algorithms are fast enough for use in energy control center applications. The economic dispatch of the total generation requirement of a power system is usually accomplished by loading each generating unit to the same incremental cost level unless otherwise constrained by the unit operating limits. However, in the actual operation, the dispatch may be dictated by fuel and operating constraints [1,2]. Fuel constraints consist of fuel supply limits by contract, and fuel consumption constraints by unit-stockpile pair and certain groups of units. Operating constraints include system generation requirements, unit operating limits, unit input/ output (I/O) characteristics and penalty factors. The paper presents network flow (NF) algorithms for solving the economic dispatch problem subject to various fuel supply and consumption constraints and unit operating limits with shared and mixed fuels. Here each constraint is represented as a limit on the amount of fuel flow in an arc of the network. The paper considers two different cases of unit I/O characteristics. First, with piece-wise linear I/O characteristics of the units, the dispatch problem is formulated as a minimum cost linear network flow algorithm.