Evaluation of Flexibility Optimization for Thermal Power Plants

Abstract

The increasing share of fluctuating renewable energy sources leads to changing requirements for conventional power plants. The changing characteristics of the residual load requires the conventional fleet to operate with higher load gradients, lower minimum load at improved efficiency levels as well as faster start-ups and provision of ancillary services. Despite the requirements from the electricity market, the value of improving those flexibility parameters is hard to evaluate for power plant operators. In order to quantify the additional benefit that can be achieved by improving flexibility parameters on a certain power plant in a changing market environment, an adjustable load dispatch model has developed for that purpose. Using past electricity market data, the model is validated for typical coal and a typical gas fired power plants by reproducing their operational schedule. In the next step, the model is used to apply parameter changes to the power plants specifications and economic effects are demonstrated. General statements are derived on which flexibility parameter needs to be improved on each power plant type. Furthermore, specific economic evaluations are shown for the reference power plants in order to present the ability of the developed tool to support investment decisions for modernization projects of existing power plants.

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“…Fossil and biomass power plants (and combined heat and power (CHP) units) need to be optimized regarding their flexibility parameters to be able to integrate as much fluctuating renewable energy as possible and in that way maintain the stability of the electrical grid. Ancillary services can be categorized as primary, secondary or tertiary frequency control reserves (Hübel et al 2018).…”

“…Alternative technologies such as large batteries are not yet available on the required scale. Studies by Hübel et al (2018) show that flexibility improve- ments at a reference hard coal power plant led to significant economic benefits compared to similar changes at a gas turbine power plant. In addition, specific improvements in cash flow can be calculated when future market price functions are used.…”