TY - JOUR
TI - Increasing flexibility of coal power plant by control system modifications
AU - Marušić Ante
AU - Lončar Dražen
AU - Batelić Jakov
AU - Franković Valdi
JN - Thermal Science
PY - 2016
VL - 20
IS - 4
SP - 1161
EP - 1169
PT - Article
AB - Expanding implementation of intermittent renewable energy sources has already  started to change the role of thermal power plants in energy systems across  Europe. Traditionally base load plants are now forced to operate as peaking  plants. A familiar transition in upcoming years is expected in Croatia and  coal power plant operators are preparing accordingly. To evaluate cycling  capabilities and control system operation for flexible operation of selected  210 MW coal plant, series of tests with different load gradients were  performed and results were thoroughly analyzed. Two possible “bottlenecks”  are identified, thermal stress in superheater header, and achievable ramping  rate considering operational limitations of coal feeders, firing system and  evaporator dynamics. Several unexpected readings were observed, usually  caused by malfunctioning sensors and equipment, resulting in unexpected  oscillations of superheated steam temperature. Based on superheater geometry  and experimental data, maximal steam temperature gradient during ramping was  evaluated. Since thermal stress was well inside the safety margins, the  simulation model of the whole boiler was used to evaluate achievable ramping  on electric side.