Impacto de contingências na análise harmônica de sistemas elétricos de potência: uma abordagem usando análise de sensibilidade baseada no teorema da compensação

Abstract

With the increasing use of alternative energy sources that require power electronics, as well as the growing introduction of nonlinear loads in general, there is a proliferation of harmonics throughout the electrical system. However, this topic is still not fully explored in its entirety. For example, there are not many current studies on the correlation and effect between contingencies and harmonic distortions in the system. Given this issue, it becomes necessary to develop new techniques capable of assessing the impact of network element outages on its harmonic state. In this context, the present dissertation proposes a method to analyze and study the variation that occurs in harmonic distortions after the occurrence of contingencies. The proposed methodology brings an approach supported by sensitivity analysis to study the change that occurs in the network after a contingency, where the compensation theorem is directly applied to estimate the new voltages in each harmonic order of interest. The analysis of the topic from this perspective has the great advantage of eliminating the need to recalculate the power flow and harmonic power flow (or other harmonic analysis methods) for each evaluated contingency. It replaces several iterative matrix calculations with simple mathematical operations that provide an approximation of the operational reality of the electrical network in an advantageous computational time. In addition to this, indexes are proposed to measure the severity of each contingency from the perspective of harmonic distortions. These indexes can be directly applied to the response provided by the sensitivity analysis to automatically and quickly find the most critical lines, enabling real-time analyses for ranking the most critical contingencies. The method is applied to three test systems: the IEEE 30-bus, the New England, and the IEEE 57-bus systems. Simulations are performed, and the results are compared with the traditional deterministic model obtained using power flow analysis. The results show satisfactory accuracy for the vast majority of cases. Additionally, the method provides a solution to the problem with a processing time up to 200 times faster than the deterministic method from the perspective of computational effort. The main contribution of this work lies in the proposal of a new method to calculate harmonic distortions after contingency events and the ability to rank the severity of each contingency considering power quality aspects, which are traditionally not investigated in this context.