Analysis of limit induced bifurcations and parameter uncertainties in the context of voltage stability

Abstract

With the continuous growth of load, Electric Power Systems (EPS) began to operate closer to its limits. Consequently, the importance of implementing dynamic safety assessment tools in the real-time operating environment has increased. In the context of safety assessments, we have the problem of voltage stability assessments by the characterization of the Load Margin (LM), which relates the current operating point and the Maximum Loading Point (MLP) of the system, limit at which voltage collapse will occur. For the calculation of the LM, several robust methods can be found in the literature for the case where the MLP is represented by a Saddle-Node Bifurcation (SNB), but the calculation of this margin in case of occurrence of a Limit Induced Bifurcation (LIB) is still subject to improvement. This bifurcation, as its name implies, occurs when the system reaches the operational limit of some equipment of the net. Also in this context of voltage stability, the high growth of intermittent sources of energy in electrical systems (photovoltaic sources and wind sources, for example) contribute to the growth of uncertainties with respect to its power balance and its point of operation. Of course, it is desirable that these uncertainties are, even if simplified, considered in the LM calculation of electrical systems with large penetration of intermittent sources. The objective of this research project is the study and the proposal of fast methods of LM evaluation, taking into account limits derived from both saddle-node and limit induced bifurcations of systems with high penetration of intermittent generation. (AU)