Off-Design Modeling of Natural Gas Combined Cycle Power Plants: An Order Reduction by Means of Thermoeconomic Input–Output Analysis

Sajjad Keshavarzian,Matteo Rocco,Francesco Gardumi,Emanuela Colombo

doi:10.3390/e18030071

Abstract

In a European context characterized by growing need for operational flexibility across the electricity sector, the combined cycle power plants are increasingly subjected to cyclic operation. These new operation profiles cause an increase of production costs and decrease of revenues, which undermines the competitiveness of the combined cycles. Power plant operators need tools to predict the effect of off-design operation and control mechanisms on the performance of the power plant. Traditional Thermodynamic or Thermoeconomic models may be unpractical for the operators, due to their complexity and the computational effort they require. This study proposes a Thermoeconomic Input–Output Analysis model for the on- and off-design performance prediction of energy systems, and applies it to La Casella Natural Gas Combined Cycle (NGCC) power plant, in Italy. It represents a stand-alone, reduced order model, where the cost structure of the plant products and the Thermoeconomic performance indicators are derived for on- and off-design conditions as functions of the load and of different control mechanisms, independently from the Thermodynamic model. The results of the application show that the Thermoeconomic Input–Output Analysis model is a suitable tool for power plant operators, able to derive the same information coming from traditional Thermoeconomic Analysis with reduced complexity and computational effort.

Highlights

According to the guidelines of EU Energy Roadmap 2050, Natural Gas Combined Cycle (NGCC)power plants may become the main backup technology in the low carbon European electricity system [1]
The performance of the gas turbine (GT) may be improved by rescheduling the on- and off-line cleaning of the compressor; the same is said for heat exchangers in the HRSG, especially the ones at lower temperatures, which are more subject to fouling
The Thermoeconomic Input–Output Analysis (TIOA) model is stand-alone, in the sense that performance predictions can be performed at every load and with different load control mechanisms, without making further use of the thermodynamic and the economic models

Summary

Introduction

According to the guidelines of EU Energy Roadmap 2050, Natural Gas Combined Cycle (NGCC)power plants may become the main backup technology in the low carbon European electricity system [1]. The average capacity factor may decrease while the amplitude of load variations, the number of ramp-up cycles, and their steepness increase. The operators are interested in lowering the generation costs and benefitting from price peaks on the market, in order to regain competitiveness. This can be attained by modifying the configuration of the power plants and the operation strategies, so as to enhance the cycling capability of the units [2,3]. The live monitoring systems of the power plants only measure and record the present thermodynamic

Methods

Results

Conclusion