Probabilistic Assessment of $\beta$ for Thermal Unit Using Point Estimate Method Adopted to a Low-Order Primary Frequency Response Model

This paper conducts a probabilistic assessment of the dynamic primary frequency response characteristic (the PFRC is also known as $\beta$ in practice) for thermal unit. The PFRC is time-varying as it is sensitive to the steam pressure and valve opening that naturally vary with the generator loading. To depict the dynamic PFRC in a probabilistic manner, an analytical expression of the PFRC is first derived by establishing a low-order primary frequency response model that considers heat storage dynamic. Based on which, the point estimate method that is capable of managing the correlation is adopted to portray the probabilistic features of time-varying PFRC for thermal unit. Numerical simulations are presented to validate the proposed low-order primary frequency response model and different solutions are applied for the probabilistic assessment of the PFRC, where the obtained results show that the proposed point estimate method can achieve satisfactory performance owing to its accuracy and efficiency.