Analysis On Factors Which Affect Frequency Dynamics Of Power System Based On Dynamic Equivalent

The investigation of frequency dynamics of large scale multi–machine electric power systems in circumstances of sudden supply deficiency is the basis of the design of the under frequency load shedding scheme of power systems .In recent years, great attention has been paid to it. With the development of power system,there are more and more factors that affect dynamic frequency characteristics that make it more and more complicated. The method that use single-generator-to-load model to analyze frequency dynamics can not suit for actual system. Analyzing the factors that affect frequency dynamics in modern power system is in great need.On the basis of analysis and computation of frequency dynamics characteristics of large scale multi–machine electric power systems, the main purpose of this paper is analyzing factors that affect dynamic frequency characteristics of northeast china power systems with larges of digital simulations of equivalent northeast china power system by PSASP under different disturbance conditions. And this paper also analyzes that the effect of disturbance locations on frequency dynamics,the phenomena of frequency oscillations and distributions and the propagations of frequency dynamics, and then the sensitivities of system frequency to generator frequency coefficient,moment of inertia and regulation dead band has been achieved and supports the rationale for design of under frequency shedding schemes .On the basis of above theories and digital simulations, this paper also introduces traditional UFLS scheme in detail, and the software for under frequency load shedding was developed to check UFLS scheme of northeast china by the user model of PSASP. The simulation results show that this scheme can adapt to many types of disturbances.