| Abstrakt: |
According to modern standards, combined cycle plants are required to participate in the primary frequency control of energy systems with the possibility of gaining up to 10 % of the rated capacity of the power unit at any time at the system operator request, which necessitates a limited operation of combined cycle plants. The paper considers the issue of reducing the economic performance of combined cycle plants under conditions of participation in the primary frequency control of energy systems. Two options for operating combined cycle gas plants under these conditions are given: controlling the power of a power unit by changing a load of gas turbines only with variable-pressure steam turbine operation and acting on the steam turbine control valves only with gas turbines operating under design conditions. The Cumulative Net Present Value, the Profitability Index, and the Discounted Payback Period have been determined under the given conditions depending on the fuel cost on an example of the power unit of combined cycle plants-325. It is shown that when the combined cycle plants participate in the primary frequency control of energy systems, economic indicators deteriorate significantly for any of the power unit operation options considered. Based on the study results, linear equations have been obtained by approximation, describing the dependence of the Cumulative Net Present Value on the fuel cost for the options considered. By solving the system of these linear equations, the fuel cost has been determined, at which one or another operation mode becomes the most economically feasible. [ABSTRACT FROM AUTHOR] |
