A Quantitative Assessment of the Impact of Renewable Energy on Power System Frequency Stability

As the power system develops rapidly into a system with a high proportion of renewable energy sources, the inertia and frequency support capacity are gradually reduced. Frequency stability has become one of the core issues restricting the security of the power grid and the efficient consumption of renewable energy sources. However, most of the present frequency stability criteria are only qualitatively analysed in the literature, and only some are related to the specific quantification of the transient frequency stability and give the relationship between variable parameters and frequency stability. In this paper, a polynomial approximation method of frequency stability index for the variable parameters affecting frequency stability in the renewable energy power system is proposed, which is based on the collocation point to establish the polynomials of the functional relationship between the variable parameters of the system and the frequency stability index. The influence of the system parameter changes on transient frequency stability is analysed using the resulting polynomial approximation function. Finally, the functional relationship between frequency indexes and variable parameters and their error is obtained by simulating the improved IEEE 39-bus system, which verifies the accuracy and effectiveness of the method proposed in this paper.