Sensitivity analysis of voltage dip computations using the TEF methods

The author previously (1989) demonstrated that the lowest voltage dip in a power system following a disturbance occurs when the system trajectory attains maximal transient potential energy. In this paper, the first-order sensitivity of this potential energy is derived and then extended to predict directly a margin for voltage dip stability. The benefit of this is the ability to predict a host of operating margins for a power system, such as generation levels, reactive power levels, and others that keep the system in a secure operating state following given disturbance contingencies. Studies done in a 39-bus system indicate that the voltage dip behaves in a nearly linear fashion for variations in the given network parameters. Even in the case of large variations in these parameters, the error produced by assuming a linear behavior is acceptable. The need for second-order sensitivity expressions is not seen, and they might be required only in some cases where improved accuracy is desired