Establishing Control Over the Residual Resource of 200 MW Steam Turbines by Optimization of Percentage of Launches from Different Thermal States

A well-known problem of the United Energy System of Ukraine is the lack of peak capacities in the total generating energy balance. For this reason, coal-fired power units with a capacity of 200 MW, which were designed to work in the base part of the electrical load graph, are involved in regulating the frequency of the power grid by changing their power, or forced stops during energy consumption reduction. At the current stage, most of the power equipment with a capacity of 200 MW has exhausted its park resource, while having a huge number of launches from various thermal states. Thus, considerable low-cycle fatigue has been accumulated in the base metal, which can severely limit service life-time of equipment. It also leads to frequent emergency shutdowns and reduces the overall reliability of the energy system of Ukraine. The paper proposes a method for establishing control over the aging equipment resource, by optimizing the percentage of the number of equipment launches from different thermal states. On the basis of a technical audit of operational documentation of generating companies and statistical processing of resource indicators for turbine equipment 200 MW of the Kurakhivska, Luhanska and Starobeshivska thermal power plants, components of independent variables were identified to solve the optimization problem. The residual service life-time was chosen as a target function, to describe which the theory of experimental planning was used, in particular, rich Rechtschaffner plans. The obtained description of the objective function in the form of a full quadratic polynomial allowed us to establish the maximum residual resource of power units of 200 MW. When operating in maneuvering modes, the maximum service life-time is provided with the following ratio of the number of launches from different thermal states: 25–39 % of starts from a cold state, 18–25 % of starts from non-cooled state and 36–57 % from a hot state of the metal.