Modern Stability Aids for Calvert Cliffs Units

Feasibility of different corrective control options for the improvement of transient stability

“…The curves in Fig. 3 are typical curves obtained based on information taken from [7][8][9][11][12][13][14] which present different curves for various FV schemes, according to manufacturer information, design characteristics and field tests. All the characteristics presented in the cited references are similar and the curves in Fig.…”

“…However, it is not recommended because the sudden drop in pressure that occurs when both valves are closing could affect the boiler and control systems negatively [8]. It is also observed that even though the valves could take around up to 6 s to completely open again, P m reacts faster and goes back to the initial value in less time, approximately 2-3 s, as shown in [7,[11][12][13][14] where the P m output versus time curve characteristics are presented, for different turbines in a FV scheme. Initial research on FV considered feasible its application in fossil-fired and nuclear units.…”

“…Even in the cases when both IV and CV are used, the output power is reduced only to around 30% of the initial value in a total time that is usually about 1 to 1.3 s. The power output goes back to the initial value 2 to 2.5 s afterwards. Theoretical approaches are discussed in [7][8][9]11] for application of FV to nuclear units. It was established that the response of nuclear units would be faster (time to reach minimum power of 0.9 s and recovery time of 1.5 s approx.)…”

“…Several corrective control methods for TSI exist, such as connection of braking resistors [1][2][3][4][5][6], fast valving schemes in thermal generators [7][8][9][10][11][12][13][14][15], switched series capacitors [16], switched shunt capacitors [17], FACTS devices [18], control of HVDC links [19], islanding schemes [19], and generator and load shedding [19]. Previous work reported in the literature studied each method independently focusing mainly in the modelling and in the control of the insertion-removal of the specific devices to optimize the impact on TSI; some existing comparative studies [18] analyzed similar Corrective Measures (CMs) based on FACTS devices.…”