Simulation of hot standby mode for flexible steam turbine operation in combined cycle power plants

摘要

A continuously growing renewable power generation during advantageous weather conditions is leading to periods without any dispatch for large scale conventional power plants. They can last several days or even weeks. The consequences of these extended shut-downs are longer power plant start-up times and moderate power ramp-up due to the low metal temperatures of the steam turbine [1]. Flexible operating profiles of the fossil power plants, however, are required to react to fluctuating power requirements. To answer this demand of high flexibility in most fossil power plants, Siemens AG developed a new feature Hot Standby Mode (HSM). This feature enables a more efficient operation of the power plant with faster steam turbine start-ups even after long standstill times. HSM is realized through an electrical Trace Heating System (THS) which is placed on the outer casing and valves of the steam turbine. The benefits are shown in Figure 1, which compares start-up curves with and without HSM after standstill. Figure 1 indicates that the start-up time can be reduced by more than 60% in HSM compared to a start-up from cold start conditions.